Theses and Dissertations Collection

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Assessment of bat guano as source of nutrients for rice production
(Sokoine University of Agriculture, 2018) Hatibu, A. A.
Rice production in Tanzania is generally low and continuing to decline partly due to low soil fertility. Smallholder farmers are continuing cultivating in the same area with little or without use of fertilizer due to limited access to costly industrial fertilizers. This trend results into continuous mining of plant nutrients such as phosphorous (P) and other essential nutrients elements which are needed by rice for growth and development; and consequently decline in soil fertility and hence rice production. The country has several bat guano deposits, but none of them are adequately exploited as alternative source of plant nutrients and soil amendment to improve the soil properties because of lack of information on their potential suitability. This study, therefore, aimed to evaluate the agronomic potential of selected bat guano for enhancing soil fertility and improving rice production. Selected bat guano in Tanzania were studied in a laboratory incubation experiment for 112 days to assess P release patterns and establish the pick periods of P mineralization in Department of Soil and Geological Sciences (DSGS) laboratory. Guanos used in this study were from Kisarawe cave A (BGK-A), Kisarawe cave B (BGK-B) and Sukumawera cave (BGS) with 8.55, 7.03 and 3.45 % total P, respectively. Guano from each deposit was mixed with soil at varying rates of 0, 10, 20, 40 and 80 mg P 200 g -1 soil. The incubation experiment was arranged as a 3x5 factorial experiment in randomized complete design (RCD) with three replications. In addition to incubation experiment pot experiment was setup to evaluate the response of rice to selected bat guano as a source of phosphorous. The experiment was carried out in a screen house at Sokoine University of Agriculture (SUA). The experiment was a 4 × 6 factorial in a Randomized Complete Block Design (RCBD) replicated three times. The treatments were three bat guano from Kisarawe cave A (BGK-A), cave B (BGK-B), and Sukumawera (BGS) and Triple Super Phosphate (TSP) as standard fertilizer all at six application rates (absolute control, 0, 10, 20, 40 and 80 mg P kg -1 soil). Bat guano was supplemented with urea (CO (NH 2 ) 2 ) which was applied at a rate of 400 mg N kg -1 and zinc sulphate (ZnSO 4 ) was applied at a rate of 2.5 mg Zn kg -1 . Rice SARO variety (TXD 306) was grown as a test crop. From the incubation experiment, results showed gradual increase of extractable/available P from 28 days to 84 days followed by a decrease in P release up to 112 days of incubation. In all days of incubation there was a highly significant interaction effect of P- sources and application rates (P < 0.05) on P released from guano applied at the rate of 80 mg kg -1 . The soil pH showed a very strong negative correlation with phosphorus released (r > 0.8) from the first day to 112 th days of incubation. The pot experiment results indicated that there was a significant (P < 0.05) effect of all three guano and standard P fertilizer (TSP) on dry matter accumulation at maturity in the order TSP > BGK-A > BGS > BGK-B. There was a significantly (P < 0.05) higher effect of P at 80 mg P kg -1 for all P sources on dry matter accumulation at maturity. Interaction effect of P sources and P rates was highly significant (P < 0.05) on dry matter accumulation at maturity. Plant physiological parameters (number of tillers, plant height, panicle height and number of panicles per plant), as well as rice grain yield were also significantly higher for plants receiving 80 mg P kg -1 for all P sources. Positive correlation between grain yield and other yield components was observed indicating better crop response to P sources and P rates applied. Both incubation and pot experiment results indicated guano to have similar effect to TSP in releasing P for rice; hence the potential for application as alterative P source. It was further observed that at application rate of 80 mg P kg -1 of guano, the studied guanos would release adequate phosphorous for plant growth. Because these results were obtained under controlled environment field trials are recommended to evaluate the response of rice and other crops to soil applied guano for meaningful recommendations to farmers.
Assessment of nitrate levels in water and soils for agriculture and human utilization in Singida district, Tanzania
(Sokoine University of Agriculture, 2016) Lwiza, M. L.
Population growth in urban areas has caused increase in demand of good quality water for domestic use. Due tohigh nitrate levels in water sources reported by District water authoritiesin Singida District, this study was carried to determine sources, levels and distribution of nitrates in water and soils for agriculture and human utilization. Firstly, a reconnaissance survey was carried to identify water sources with high, medium and low levels of nitrates and determine nitrate levels in surrounding soils. Surface water, underground water and surrounding surface soils samples were randomly collected and analysed for nitrate levels.Their results assisted in identifying areas with high, medium and low nitrate levels where detailed soil sampling and analyses for nitrate levels in soils was carried out.Analysis of soils and water resources revealed high levels of nitrates in water samples ranging from 105 to 476mgL-1and25.2 to 114.8mgkg-1in soils.The distribution of soil nitrates along transects indicated that higher levels were recorded at lower slopes whilelower levels were recorded in the upper slopes. The distribution of nitrate with soil depth was quite variable. In some areas the soil nitrate levels increased with increasing soil depth while in other areas nitrate levels decreased with increasing depths.The nitrate levels in water found to beabove the tolerable limits of 20 mgL-1 and 50 mgL-1set by TBS (2005) and WHO (2007),respectively. Nitratelevels in soils are within the tolerable limits forcrop production. Due to observed high nitrate levels in water, more researchis required to generate sufficient data on the suitability of water for human consumption. The study on the dynamics ofnitrate in soils and water is recommended in orderto come up with strategies of reducing nitrate levels in water.
Assessment of the fertility status of soils of rice growing areas of Same District, Kilimanjaro Region, Tanzania.
(Sokoine University of Agriculture, 2003) Amur, Nyambilila
This study was conducted to assess the fertility status of the soils of rice growing areas of Same district. Thirty soil samples were collected from ten different sites where rice is grown. Following laboratory analysis, three bulk soil samples were collected from Kisiwani, Ndungu and Kihurio for pot experiments. The laboratory analysis included determination of total N, organic carbon, P by Bray 1 and Olsen methods, and exchangeable bases by ammonium acetate saturation. The micronutrients were determined by extracting with 0.005M DTPA at pH 7.3. The response of rice (Oryza saliva L) variety super SSD5 to N, P and K, as well as to different levels of Zn were assessed in a glasshouse experiment where plants were grown for 56 days. The harvested plant samples were analysed for N, P, K, Ca, Mg, Zn and Fe using the HNO3-H2O2 wet digestion procedure. The results showed that all the soils in this study were deficient in N. About 53% of the soils had low available P. All the soils had adequate levels of K, Ca, Mg and Na, with the exception of soils from Ndungu, which had a low K, supply. Also, most of the soils had low Zn levels, and only two sites had adequate Zn levels. Soils from Mbugani had low Fe while the rest had adequate Fe and Cu. The glasshouse experiments showed that application of N, P and K increased rice dry matter yields in all the soils used. It was further revealed that Zn supplementation in addition to NPK also increased rice dry matter yields further. The results also indicated that the uptake of each nutrient applied was consistent with the dry matter yields increases. It was concluded that most of the soils under rice cropping in the district were deficient in N, P and Zn and required fertilisation using these nutrients. Iron was also required in Mbugani soils, whichiii were deficient of this element. Field experiments are recommended to confirm these initial findings.
Assessment of the impacts of climate variability and change on rainfed cereal crop productivity in central Tanzania
(Sokoine University of Agriculture, 2015) Msongaleli, Barnabas M.
Though production of cereal crops in Tanzania could succumb to the projected climate change, research has mainly focused on maize (Zea mays L), the main staple crop for the country, and just little work has been done to analyse climate change impacts specifically on sorghum [Sorghum bicolor (L) Moench]. This study analysed the nature and sources of vulnerability on sorghum production by smallholder farmers due to climate variability and change and evaluated possible farm-level adaptation options that can enhance the adaptive capacity of smallholder farmers in the face of increased climate variability and long-term change in climate. The study was conducted in Dodoma and Singida regions in central Tanzania. Local famers‟ management practices from databases and surveys were combined with field experimentation and simulation modelling. The Agricultural Production Systems SIMulator (APSIM) and Decision Support System for Agro-technological Transfer (DSSAT) models were calibrated and validated to predict growth and yield of sorghum under rainfed conditions in the case study regions. Three sorghum varieties: Macia, Pato and Tegemeo were used. The models were parameterized using different agronomic parameters (phenological development, dry matter accumulation and grain yield) and climatic data. Efficiency of the models were tested using model validation skill scores including d-stat, root mean square error (RMSE) and regression coefficient (R 2 ). To understand the nature of vulnerability, long term historical rainfall data were analysed. Simulations were conducted to evaluate the impacts and interactions of adaptation options, namely: staggered planting dates, recommended planting density, and variable fertilizer rates on sorghum and maize yields under long-term climate change towards the mid-century. The long-term rainfall analysis shows that total annual rainfall has so far notiii changed, but variability in the rainfall distribution within seasons has increased. Experimentation in this study demonstrated that the tested sorghum varieties had variable maturity dates and different responses to prolonged dry spells. Thus, the early maturing variety Macia (102 days) was able to avoid terminal drought versus Pato (118 days) and Tegemeo (114). Statistical analysis show a significant (at 0.05 level) inter-seasonal effect on grain yield and total biomass of the sorghum varieties. Agricultural production systems in semi-arid central Tanzania are projected to be affected by expected changes in climatic conditions over the next decades and century. Simulation results show that Macia will not be affected by climate change. In contrast, early maturing maize variety Situka was not able to compensate for the decline in yield under climate change. However, fertilizer application increased Situka yield significantly under future climates particularly when early planting was adopted. Coupled with increasing population pressure and declining soil fertility, climate variability and change are relentless driving forces to reduce agricultural productivity in the near future. Because agriculture causes a variety of benefits and challenges, impacts of climate change on agricultural systems are of importance from an economic but also from a social and environmental point of view. Assessment of impacts and potential adaptation supports the decision making processes of farmers, governments, and other stakeholders. Adaptation options such as changes in sowing dates, changes in planting density and fertilizer application were evaluated. To adapt to the changing climate, early sowing and increasing plant density per hectare and fertilizer application would be feasible options. The selection of an earlier sowing date for maize, for instance, would be the appropriate response to offset the negative effect of increased temperature. This change in planting date would allow for the crop to develop during a period of the year with loweriv temperatures, thereby decreasing developmental rates and increasing the growth duration, especially the grain filling period. The study also found that site specific agro-ecological conditions such as soil type characterize farmers‟ responses to decisions on the type of crop and/or crop variety to grow in a given season. This is partly due to their perceptions on soil fertility status among soil types taking spatial variability across the fields into account. Other socio-economic factors ranging from food tastes and preferences to markets and prices, variably but strongly influence decisions on continued adoption of drought tolerant crops (sorghum and millets) versus the susceptible maize. The results show that these factors and associated challenges have the potential to bring negative externalities, therefore, efforts to minimize the impacts from climate variability and change should go alongside with addressing the reported perception and preference challenges. Soil fertility management is therefore likely to be a major entry point for increasing the adaptive capacity of smallholder farmers to climate change and increased climate variability. However, management of other factors related to improved varieties, nutrient resource access and socio-economic factors is critical for rainfed cereal production under changing climate. This dissertation addresses impacts and adaptation to climate change on sorghum production (with some comparison with maize) in the central zone of Tanzania. An overview over different approaches of modelling climate change impacts on crop production as well as a review of studies that analyse climate change impacts on agriculture in sub-Saharan Africa and Tanzania in particular are given in the introductory Chapter 1. Chapter 2 describes the evaluation of the performance of three sorghum varieties at the field level and assessment of their performance over a long-term period using biophysical modelling. In Chapter 3, an approach that integrates the biophysical modelsv DSSAT and APSIM model with GCMs is used to analyse the impact of climate change on sorghum and maize production. Chapter 4 investigates the influence of driving factors separate from impacts of climate change on the production of sorghum relative to other cereals important in the zone. General discussion and conclusions are given in Chapter 5.
Assessment of the nitrogen and phosphorus needs and use efficiencies for enhanced maize yields in Mbozi district of Tanzania
(Sokoine University of Agriculture, 2014) Liduke, L.
A study was conducted in Lumbila, Senjele, Mbimba and Ihowa villages of Mbozi district, Tanzania during 2012 – 2013 cropping season to assess the fertility status of the soils and response of maize to N and P as a strategy for enhanced and sustainable maize production. This study was triggered by the low maize yield in Tanzania due to many factors which include declining soil fertility, soil N and P being the major constraints to maize production. The search for the most appropriate rate of N and P fertilizers in relation to maize that would result in optimum yields prompted this research to be conducted. The experiment was laid as Randomized Complete Block Design with three replications. Maize variety used was “UH 615” with fertilizer treatments of Urea (46%N) and TSP (46% P2O5). Based on the soils analytical data, the major soil limitations for increased and sustainable maize production at the study areas include the deficiencies of N, P, Ca, Zn and low in OM. Application of 80 kg N ha-1 + 20 kg P ha-1 and 120kg N ha-1 + 20 kg P ha-1 significantly (P ≤ 0.05) enhanced maize growth and yield more than other treatments, however, the effect was insignificant on harvest index of maize. Application of N at the rates of 40, 80 and 120 kg ha-1 and combining each rate with 20, 40 and 60 kg P ha-1 reduced NUE while increased PUE of maize in all experimental sites. These findings suggest that as NUE decreased the PUE is increased. This could be related to the increase in N and P imbalances in soils as the rates of N applied increased. Results also indicated an inverse relationship between the higher doses of fertilizer application and benefit cost ratio. Application of 80 kg N ha-1 + 20 kg P ha-1 and 120kg N ha-1 + 20 kg P ha-1 produced the highest maize yields equivalent to 4.4 and 4.2 t ha-1 with the gross return of 2,112,000/= TSh and 2,020,800/= Tsh ha-1 with respect to BCR, respectively. This study further confirmed the role of N and P fertilizers in increasing growth and grain yield in maize production. From these results application of 120kg N ha-1 + 20 kg P ha-1 may be recommended for increasing maize yields particularly in the study areas. However, application of 80 N ha-1 + 20 kg P ha-1 can also increase in the yield of maize. This will greatly benefit farmers in Mbozi district where the supply of N fertilizer is low and cases where farmers cannot afford the cost of high fertilizer input. It is also recommended that while there is a wide-scale adoption of blanket fertilizer recommendation there is a need for site-specific nutrient management for balanced fertilization.
Assessment of the potential of Siam weed (Chromolaena odorata) in enhancing soil fertility status in Serengeti District, Tanzania
(Sokoine University of Agriculture, 2015) Mbalila, Schola
Siam weed (Chromolaena odorata) is a plant that has infested a large area of agricultural land in Serengeti district and has adversely reduced crop land and crop yields. It is encroaching land and especially in the famous Serengeti National Park. The weed has been reported to contain high amount of plant nutrients in its tissue, hence its probable use as an organic soil amendments, with aspect to soil fertility improvement. A study was, therefore, conducted to address the Siam weed growth requirements, nutrient contents in its tissue and its suitability and use as an organic amendments as a way to manage the weed accordingly and appropriately. Soil and Siam weed plant sampling was done in the Serengeti district (Mara Region), an analysis was done in the Soil Science laboratory at SUA, Morogoro. Composite topsoil (0 – 20 cm) samples were collected and analysed for physico-chemical properties hence shows to have slightly acidity with pH (5.8 to 6.5), low to high CEC (11.6 - 29.4 cmol (+) kg −1 ) and very low to very high soil organic carbon (0.36 - 3.69%). Three soil profiles on a toposequence from the infested soil were excavated, described and sampled for soil laboratory analysis, hence shows medium acidic to medium alkaline (pH 5.84 to 7.93), low to high CEC (10.12 - 35.20 cmol (+) kg -1 ), low to medium SOC (0.11 - 1.97%) and high exchangeable bases 24.45 cmol (+) kg −1 based on the rating by Landon (1991). Using the morphological and laboratory data the soils were classified to the subgroup level of the USDA Soil Taxonomy as Ustic Torripsamments on sloping land, as Haplic plinthustults on midslope and as Plinthaquic paleudalfs on low land and to Tier-2 of WRB as Rendzic Lithic Leptosols (Eutric, Dystric, Tephric) on sloping lands, as Gleyic Plinthic Acrisols (Ferric, Humic) on midslope and as Haplic Stagnic Gleyic Luvisols (Chromic) on low or flat areas. Incubation study was done by incorporation of different parts of Siam weed plant with soil for 16 weeks. As a result of mineralization after incubation, the leaves released N (0.292%) and Fe (64.15 mg kg -1 ); bulbs released P (12.39 mg kg -1 ) and Mg (0.87Cmol (+) kg -1 ); stems released K0.22 cmol (+) kg -1 ) and Ca (5.13 cmol (+) kg -1 ) and roots released Cu (6.01 mg kg -1 ), Mn (77.18 mg kg -1 ) and Zn (1.65 mg kg -1 ). Nutrients released were increasing from the 0 to 12 th week and started to decrease at week 16 after incubation. Therefore, from incubation results, it is recommended that, farmers should grow their crops before the 12th week following incorporation of Siam weed biomass into soils for plants to absorb nutrients from the Siam weed.
Assessment of uranium levels in waterand soils and its uptake by sorghum and sunflower in Singida Urban District, Tanzania
(Sokoine University of Agriculture, 2016) Kaishwa, S. J.
In Tanzania, uranium deposits have recently been found in Bahi and ManyoniDistricts. Due to suspected high uranium levels in water sources as reported by District water authoritiesin Singida District, this study was carried out to determine levels of uranium in soils, and water and its uptake by commonly grown food cropsfor enhancing public awareness and safety to the residents of Singida Urban District. Rock, soil and plant samples were collected randomly from farmer’s field.Water samples were collected from various water sources in Singida Urban District. Laboratory analyses of soil, rock and plant samples werecarried out at the Geological Survey of Tanzania in Dodoma and Soil Science laboratory at Sokoine University of Agriculture while water samples were analysed atthe Government Chief Chemist Laboratory in Dar es Salaam. Results foundin soil, water, and rocks. The highest U level in soil of 15.4mg kg-1was obtained at Burudani area and the lowest level of<0.01mg kg-1was obtained at Kwa Askofu area. The concentration of uranium in rocks ranged from 20.1 to 31.5 mg kg-1, which in some places washigher than the critical level of 23 mg kg-1 recommended for agricultural land use. Uranium concentrations in sorghum and sunflower grainswere found torange from 1.4 to 5.2 mgkg -1, while in leaves it was less than 2.3 mgkg -1. Uranium concentrations in water ranged from 0.058 to 1.097 mgL-1, the values which were higher than 0.03 mgL-1tolerable limit set by WHO for human and animal consumption. It was concluded that uranium contents found in soils are within the tolerable limit set for agricultural use and consequently sorghumand sunflower grown in the District are safe for human and animal consumption. Most water sources in the District had higher levels of Uranium and thus, should not be used for safety reasonsunless they are treated to reduce uranium concentration. Further studies are recommended to assess uranium concentration in fish, and soda ash,which are produced from lakes and in Singida Urban District.
Biological nitrogen fixation in legume-legume and legume-cereal intercrops: Effects on yields of subsequent maize crop in Central Malawi
(Sokoine University of Agriculture, 2016) Njira, K. O. W.
Declining soil fertility continues to be one of the most important challenges in Malawi’s crop production systems, with nitrogen considered as the most limiting nutrient element. However, food legume crops such as pigeon pea (PP) and cowpea (CP) are popular amongst smallholder farmers as they contribute to food security and protein nutrition, source of income to farmers and contribute to soil fertility improvement through biological nitrogen fixation (BNF). They are grown in various cropping systems such as sole cropping, legume-cereal and legume-legume or “doubled-up” intercrops. However, information on BNF, crop productivity, vesicular arbuscular mycorrhizal (VAM) fungal colonisation and contributions of the pigeon pea-cowpea intercrop to subsequent maize (MZ) yields and grain quality is scanty. Therefore, a study to address the aforementioned information gaps was conducted in the 2013/14 and 2014/15 cropping seasons on the Chromic Luvisols of Lilongwe and Dowa districts of Central Malawi. Specific study sites were at the Lilongwe University of Agriculture and Natural Resources (LUANAR), Department of Crop and Soil Sciences Research Farm (14o 11′ S, 33o 46′ E) and at Nachisaka Extension Planning Area (EPA) (13o 37′ S, 33o 56′ E) in Lilongwe and Dowa districts, respectively. The study was aimed at optimizing pigeon pea and cowpea intercropping practices for increased yields of subsequent maize in rotation. Specifically, it included evaluation of the extent of nodulation and BNF by the PP and CP and their productivity in sole cropping, legume-legume and legume-cereal intercropping systems. Additionally, the VAM fungal colonisation of the PP and CP-based systems and rotational maize, and its contribution to the BNF and crop growth was also assessed. Furthermore, N mineralization patterns in the legume-based system plots with residues retained and the rotational maize plant N uptake were assessed. Finally, maize grain and total dry matter (TDM) yields, harvest index percentages (HI %), grain crude protein contents and nitrogen use efficiencies (NUE) in the subsequent season were evaluated. In the first cropping season (2013/14), the experiment was arranged in the randomized complete block design (RCBD) whereby pigeon pea, cowpea and maize were grown as sole crops, legume-cereal and legume-legume intercrops. The split plot design was used in the second cropping season to grow maize in an integrated soil fertility management (ISFM) approach in which the legume-based systems with residues retained in their plots were the main plots and the 0, 45, 90 and 120 kg ha-1 N fertilizer applications formed the sub-plots. Results showed significant effects of the cropping systems on the performance of the PP, CP and MZ crops. Nodulation was significantly increased (P < 0.05) under sole cropping. Sole cropped PP nodule dry weights were significantly higher (P < 0.05) by 25% and 48% than those of PP in intercrops with CP and MZ, respectively, in the Lilongwe site. Similarly, the nodule dry weights were also significantly higher (P < 0.05) by 25% and 46% compared with those in PP in intercrops with CP and MZ, respectively, in the Dowa site. Significant differences in PP nodule numbers were noted for Dowa, with only slight differences in Lilongwe site. Furthermore, sole cropped CP produced significantly higher (P < 0.05) nodule dry weights by 38% and 36% than that in CP in an intercrop with PP or MZ, respectively, in the Lilongwe site. Similarly, intercropping systems decreased the percentage of nitrogen derived from the air (%Ndfa) and the total amount of N2 fixed by each of the two legume species. The highest amount of biologically fixed N or N2 fixed (92.9 kg ha-1), which was significantly higher (P < 0.05) than that by the PP under both the PP-CP and PP-MZ intercrops by 31% and 36%, respectively, was noted in the Dowa site. However, a comparison of the overall cropping system BNF contribution per unit area showed the combined amount of biologically fixed N (82.9 kg ha-1) from the two component legume crops in the PP-CP “doubled-up” was comparable to that by the sole cropped PP, at the Dowa site. Furthermore, the PP-CP doubled up BNF at Dowa was significantly higher (P < 0.05) than the amounts of N2 fixed by the sole cropped CP (62.5 kg N ha-1), pigeon pea in the PP-MZ intercrop (59.9 kg N ha-1) or CP in the CP-MZ intercrop (13.1 kg N ha-1). However, a different trend was noted at the Lilongwe site. Although the biologically fixed N (85.7 kg ha-1) by the sole cropped pigeon pea was similarly the highest, the combined amount of N2 fixed (57.4 kg N ha-1) by the PP and CP in the pigeon pea-cowpea “doubled-up” was significantly lower than that by the sole pigeon pea, by 33%. From this study it was concluded that both legume-legume and legume-cereal intercropping reduces nodulation and BNF per plant but the overall amount of nitrogen fixed per unit area by the PP-CP “doubled up” can be comparable to that by the sole cropped PP depending on environmental conditions. Similar to the BNF, grain and TDM yields per plant and HI%, were also decreased by the intercropping systems. However, the productivity by all the intercropping combinations (PP+MZ, PP+CP and MZ+CP) was higher than under sole cropping as they all resulted in LERs of greater than one and positive monetary advantage index (MAI) values. The PP+MZ intercrop showed to be the most beneficial in terms of both yields and monetary gains as it produced highest LERs and MAI values at both sites of Lilongwe and Dowa. Furthermore, the partial LERs, relative N and P yields showed maize to be the most resilient when intercropped with either PP or CP whereas cowpea was the most suppressed when intercropped with either PP or MZ. Additionally, the VAM fungal colonisation was not affected by the PP and CP-based cropping systems such as sole cropping, legume-cereal and legume-legume intercrops. However, a weak positive relationship was noted between VAM fungal colonisation and yields, P uptake or BNF. Furthermore, all the legume-based cropping systems led to significant increases of the VAM fungal colonisation of the subsequent maize roots by ranges of 39 to 50% and 15 to 36% in the Lilongwe and Dowa sites, respectively, which showed potential of the PP and CP based systems in influencing the P uptake enhancing VAM associations. Furthermore, interactive effect of the legume residues and inorganic fertilizer led to higher maize grain yields by a range of 30% under treatment that was previously CP+MZ intercrop (1689 kg ha-1) to 59% under treatment that was previously sole cropped CP (2864 kg ha-1) at 0 kg N ha-1 fertilizer application than the treatment that was previously sole cropped MZ (1178 kg ha-1), in the Lilongwe site. Similarly, at the highest rate of N application, 120 kg N ha-1, treatments that were previously legume-based produced higher grain yields than the treatment that was previously sole cropped MZ (3277 kg ha-1) by a range of 28% under treatment that was previously CP+MZ intercrop (4525 kg ha-1) to 42% under treatment that was previously sole cropped CP (5665 kg N ha-1), at the Lilongwe site. A similar trend was observed at the Dowa site. Furthermore, from this study it was shown that mixing high quality pigeon pea and cowpea with the low quality maize residues increased mineralization rates, N uptake, and nitrogen use efficiency by the maize grown after the legumes in rotation, with implications on yields. In addition, increasing inorganic N application increased maize grain crude protein content in both study sites, which indicates increased grain quality. Therefore, it was concluded that for smallholder farmers on the Chromic Luvisols of Lilongwe and Dowa districts, central Malawi, an ISFM approach involving PP and CP, either as sole crops, legume-legume or legume-cereal intercrops can substantially increase rotational maize yields, both quantitatively and qualitatively with the implication on reducing the investment costs of inorganic fertilizers.
Carbon sequestration and nitrogen addition in selected soils of Morogoro, Mbeya and Ruvuma under maize-soybean intercropping and rotations
(Sokoine University of Agriculture, 2022) Hamadi, Said
This study was conducted in some selected soils of Morogoro (Magadu) and Mbeya (Uyole) regions of Tanzania to classify and characterize their properties. Two representative pedons (SUARAT-P1 and UYOLE-P1) were dug and described using FAO guidelines clarifying morphological features, physico-chemical properties and genesis. The representative pedons were geo-referenced using Global Positioning System (GPS) receiver. A total of nine (9) genetic soil horizons were identified from both sites and samples from each horizon collected for physical and chemical analyses. Soils from both sites were very deep and topsoil moist colors ranged from hue of 7.5YR to 10YR with chroma of less than 3 in SUARAT-P1 and UYOLE-P1 pedons. Soil structure ranged from strong fine crumbs in topsoils to medium coarse sub-angular blocks in subsoils of SUARAT-P1 while UYOLE-P1 had weak fine sub-angular blocks in topsoils and subsoils. The SUARAT-P1 had sandy clay (SC) texture in topsoil and clay texture in subsoil while UYOLE-P1 was sandy loam (SL) in topsoil and sand clay loam (SCL) in subsoil. Soil reaction were slightly acid to very strongly acid in SUARAT-P1 (pH 6.54 - 4.46) whereas UYOLE-P1 were slightly acid to neutral in the subsoil horizons (pH 6.35 – 7.32). Organic carbon ranged from very low to low (0.12- 0.95%) in SUARAT-P1 from 0-23 cm and medium (1.5%) from surface to 25 cm depth in UYOLE-P1. Nitrogen levels were very low to low (0.05 - 0.12%) in both sites, whereas available P ranged from low (0.30 mg kg - 1 ) to medium (8.55 mg kg -1 ) in both pedons. The figures for soil OC and N will be used as baseline to forecast SOC and N sequestration potential in selected study sites. CEC of SUARAT-P1 was medium ranging from 12.4 to 23.2 cmol(c) kg -1 , whereas UYOLE-P1 was medium to high (15 – 34 cmol(c) kg -1 ). The figures for soil OC and N will be set as baseline for SOC and N sequestration studies in the next chapters. In SUARAT-P1, topsoil BS was high (> 50%) and low (< 50%) in the subsoil while UYOLE-P1 registered high BS throughout its profile depth. As diagnostic horizons for soil classification, the SUARAT-P1 had an ochric epipedon overlying a kandic horizon and classified according to USDA Soil Taxonomy as Typic Kandiustults, while UYOLE-P1 had an ochric epipedon over a cambic horizon and was named as Andic Dystrudepts corresponding respectively to Haplic Lixisols and Eutric Andic Cambisols in the WRB for Soil Resources. The results have indicated that, studied soils are less fertile with possible reconstitution through land and crop management practices which include but not limited to no-tilling or conservation tillage, manuring and proper fertilizer application; residue retention, possible fallowing, liming for potential buffering of soil pH especially at SUARAT-P1 and crop rotation and intercropping with leguminous crops.
Characterization of selected gypsites of Tanzania and assessment of their effectiveness as plant nutrient source and soil amendment
(Sokoine University of Agriculture, 2015) Andrea, Primitiva
This study was carried out to assess the suitability and effectiveness of gypsite as soil amendment in release of Ca and S. This is because besides the high potential of gypsite in improving crop yields in some countries, its use in Tanzanian agricultural soils is limited. This is attributed largely to few researches on their agricultural potentials. The gypsite samples used in this study were collected from Pindiro, Makanya, Itigi and Msagali sites. The X-ray fluorescence (XRF) method was employed to analyze the chemical compositions of the composite samples. Using maize as a test crop, pot experiment was conducted to assess crop response to gypsite application at different rates. In addition, incubation study was conducted for 56 days on the solubility of gypsite in release of S in soil solution. The XRF results showed that the gypsites from the four sites varied in amounts of gypsum content from 35.76 to 82.36% for gypsite from Itigi and Pindiro respectively. The contents of S were 15.32, 13.26, 10.52 and 6.65 % for Pindiro, Msagali, Makanya and Itigi gypsites respectively. Calcium contents was 11, 9.5, 7.6 and 4.8% for Pindiro, Msagali, Makanya and Itigi gypsites, respectively. Pindiro and Msagali gypsite sources were selected for pot experiment due to having high S and Ca percentage. Results from pot experiment indicated that maize plant height and shoot dry matter were significantly higher by 22% and 27.2%, respectively for soil amended with Pindiro and Msagali gypsites compared to maize grown in none amended soil. After pot experiment, the postharvest soil analysis indicated that on the average residual S increased by 5 for soil amended with Pindiro and 2 times for soil amended with iii Msagali gypsite while Ca increased by 19.6 and 21.7% for soil amended with Pindiro and Msagali gypsites, respectively, compared to control. In addition, incubation results revealed that solubility of gypsites for Pindiro and Msagali were high (178 to 579 and 165.1 to 492.2 mg S kg-1) respectively. Gypsites from Pindiro and Msagali are effective in improving Ca and S availability for plant growth, also gypsite application has acidifying effect to the soils. In this study gypsite application reduced the pH by 0.4 units. However, field trials using different soil types and various crops are recommended in order to make concrete recommendations on use of these soil amendments.
Characterization of vermiculites from the Mozambique b elt of Tanzania for agricultural applications
(University of Aberdeen, 2009) Marwa, Ernest Melkiory Magesa
Crop productivity in Tanzania is generally low and this is partly due to inadequate and poor retention of plant nutrients and moisture by some soils. The country has several vermiculite deposits, but none of them are exploited to improve the soil properties because of lack of information on their potential suitability. The aim of this research was to establish the suitability of vermiculites from Tanzania as soil improvers for crop production through characterization. The study involved five samples from Tanzania and one from South Africa, which was included for comparison purposes. Mineralogy of the samples was studied by a combination of X-ray diffraction (XRD) and scanning electron microscopy (SEM) fitted with energy dispersive system (EDS), whereas electron probe microanalysis (EPMA) and inductively coupled plasma-mass spectrometry (ICP-MS) were used to establish elemental compositions. Extractability of some heavy metals in vermiculites was assessed by diethylene triamine pentaacetic acid extraction (DTPA), whilst extractable P was determined by acetic acid extraction. The pH, water release characteristic, and cation exchange capacity (CEC) were among the physical and chemical properties assessed. Pot and field studies were then carried out in Tanzania to assess maize response and retention of macronutrients in a sandy soil amended with vermiculites. Maize was used as a test crop. The results found indicate that not all samples are vermiculites, some are hydrobiotites. Analysis shows that none of them contain hazardous accessory minerals. However, some have elevated concentrations of Cr and Ni, but these heavy metals are insignificantly plant available and do not inhibit the uptake of essential plant nutrients. Hence, the studied vermiculites are safe to exploit for crop production. In addition, all are slightly alkaline with high CEC and, thus, they are suitable as a growing medium with ability to retain plant nutrients from leaching. However, heating above 600 °C should be avoided as it reduces the CEC of vermiculites by more than 90 % and makes some of the exfoliated products strongly alkaline and, thus, unfavourable for crop production. The Tanzanian vermiculites can retain plant-available water but their ability is less than vermiculite from South Africa. The P in these vermiculites is extractable and extractability increases on heating to 400 °C. Further heating makes P insoluble and less extractable. Maize vegetative growth, dry matter yield, and nutrient uptake were significantly enhanced by adding vermiculite to the soil over the control. In addition, it retained and fertilized the soil with P. Pre-heated vermiculite at 600 °C performed better than unheated vermiculite and it inhibited the fixation of the applied K and N. It was concluded that the Tanzanian vermiculites have a recommendable potential of improving soil properties for crop production when heated at a temperature of not more than 600 °C. However, more field trials are recommended on other types of soils and crops other than sand and maize used in order to widen the scope of their utilization in Tanzania.
Comparative effects of minjingu phosphate rock and triple super phosphate on residual p in an ultisol
(Sokoine University of Agriculture, 2011) Kalala, Asheri Mwamba
The use of relatively high rates of phosphorus (P) is known to result in a build up of P in soils and there are frequent claims that the use of phosphate rocks results in higher residual effects than water soluble sources. Thus the objective of this study was to assess residual P in treatments where relatively larger amounts of P from triple super phosphate (TSP) and Minjingu phosphate rock were applied. Total amount of P applied was 480 kg P /ha applied to Kanhaplic Haplustult at the Sokoine University of Agriculture farm. Residual P was assessed by Bray I extraction, sequential P extraction and growth of maize plants on soil samples collected from the treated soils as well as from the control treatment. The assessment of residual P was done seven years after P application was stopped. The results indicated that Bray I-P increased from 3.4 mg /kg in the control to 26.1 and 33.1 mg /kg in the MPR and TSP treatments, respectively indicating that MPR and TSP had comparable effects on residual available P. The total labile P increased by 45.3 and 50.2 mg /kg in TSP and MPR, respectively. The moderately labile P increased by 104.3 mg /kg and 77.0 mg /kg in TSP and MPR, respectively indicating that the residual P fractions from the two sources were different in P being held strongly by chemisorptions to Fe and Al components of soil surfaces. The increase in total recalcitrant P fraction was relatively higher in the MPR (114.4 mg/kg) than TSP (49.5 mg /kg) treatment. The pot experiment results showed that the P uptake from residual P in MPR and TSP treatments were comparable with 123.2 and 121.2 mg /pot, respectively but were significantly higher than the control treatments. Addition of fresh P applications into soil with residual P resulted in higher extractable P and P uptake than residual P alone. Recommended P applications from fresh TSP and MPR were comparable iniii maize P concentration and uptakes. The contributions of total labile P, moderately labile and HCl- P on P uptake were 58 %, 64 %, and 49 %, respectively. It was concluded that application of a relatively large rates of P either as MPR or TSP resulted in relatively high levels of residual available P seven years after P application was stopped but the levels achieved were below optimum under pot conditions.
Developing an integrated soil fertility management decision support tool for arabica coffee (coffea arabica) in selected areas of northern Tanzania
(Sokoine University of Agriculture, 2014) Maro, Godsteven Peter
Coffee is one of the major export crops in Tanzania, contributing 24% to the agricultural gross domestic product (AGDP). The crop contributes directly to the livelihoods of over 420 000 farm families and indirectly to over 2 million people employed in the coffee value-chain. The Tanzanian average coffee production is variably pegged at 45 000 – 52 000 metric tons annually, while smallholder coffee productivity per tree ranges between 250 and 300g of parchment which is low compared to the world average of 500 – 600 g per tree. In the northern zone, for instance, annual coffee production trend indicates a decline over years as from 1980. During the first coffee stakeholders’ conference in 2009, soil fertility decline was pointed out by representatives of coffee growers as one of the most limiting factors for coffee productivity and sustainability. In the absence of a clear soil fertility intervention strategy in the coffee growing areas, with scanty and incoherent soil fertility data and limitations in their reliability and usability, it would seem impossible to verify the farmers’ claims or devise an intervention pathway. This formed the rationale of this work, whose objective was to develop a system that will make the soil analytical data useful for coffee farming. A model was required to quantitatively translate the soil data into estimated coffee yield, and also to recommend nutrient input application for best returns. This study was undertaken in Hai and Lushoto Districts, Northern Tanzania. The two districts were picked on merit of both growing coffee (thus experiencing the problem of coffee productivity decline) and each belonging to different geological origins (volcanic and metamorphic-gneissic parent materials, respectively). The first task was to establish the farmers’ perception of soil fertility decline as a problem and their attitudes towards integrated soil fertility management (ISFM) for coffee, thereby identifying the appropriate intervention strategies. Based on questionnaire data involving 126 respondents, both farmers’ awareness of the problem iii and their attitude were highly significant (at p<0.01). Age, total land area under coffee and total off-farm income negatively affected farmers’ attitude. As farmers get older, they tend to refrain from innovation. For the two districts, ISFM interventions will make a better impact to younger and more energetic farmers with enough land for coffee production and who depend largely on this crop for their livelihood. It was therefore concluded that the interviewed farmers echoed the concern that their representatives made in 2009. Another study was conducted to assess the soil fertility status against the soil fertility requirements for Arabica coffee, thus scientifically verifying the above concern. A total of 116 soil augerings and 10 soil profiles were described, and soil samples analyzed for the key soil fertility parameters. Soil fertility was assessed qualitatively, quantitatively and spatially. It proved to be considerably low in the study areas, and much lower in Lushoto than in Hai. Immediate recommendations to address the declining soil fertility were given, which include integrated farm management, adequate supply of essential nutrients and building capacity to produce high quality soil data and to interprete them in terms of coffee productivity. Following the two earlier studies, a review of existing crop models was made and a Wageningen model called QUEFTS was picked as a benchmark. It was recalibrated with the coffee crop in mind, and a new model called SAFERNAC (Soil Analysis for Fertility Evaluation and Recommendation on Nutrient Application to Coffee) was developed. The model was checked for accuracy and applicability and found to be capable of reproducing the actual yields by 80-100%. The new model, tested with soils of Hai and Lushoto Districts, proved to be a useful tool for coffee land evaluation and ISFM planning. Through a screen house experiment, different organic materials were tested for nutrient release potential and the data used as inputs to the model for yield estimation under different nutrient management options. Mineral N, P and K release varied significantly (P<0.001) among the organic materials and between the two soil types representative of the study areas. The model demonstrated its potential in iv suggesting appropriate nutrient management options for both organic and conventional farmers, and showed that green manure plants have great potential in coffee ISFM. The model was further expanded to involve prices of inputs and outputs for the determination of net returns and coffee profitability. It was used to obtain yields from a soil of known properties receiving different levels of input N, P and K from both organic and inorganic sources (ISFM). The costs of inputs were derived from experiences in Northern Tanzania, while coffee prices were estimated to range between 1250 and 2500 TZS kg-1. The economically optimum input applications (in equivalent terms) that gave highest net returns and value: cost ratios were found to be 401, 332 and 418 kE ha-1 for soils of low, medium and high fertility, respectively. The recommendations emanating from this study are outlined hereunder: 1. ISFM efforts should focus on younger and more energetic farmers with enough land and who depend largely on coffee for their livelihood. TaCRI and other coffee stakeholders should devise a programme to encourage young people to take coffee farming as a viable business. 2. Factors affecting farmers’ decisions on fertilizer use should be taken into consideration in devising an ISFM strategy for the coffee farmers. 3. TaCRI and the coffee extension machinery at district level should continue to promote the right kind of nutrient management strategy to the farmers. Also, promotion of the improved coffee varieties among farmers should continue. 4. Farmers should be encouraged to come forward and pre-test the model under TaCRI guidance. The pre-testing should include interested organic and conventional farmers around Lyamungu and Yoghoi, specifically to test the target yield and respective ISFM options suggested. v The following activities are envisaged for future perfection of this work: 1. To continue research on the four green manure plants (Mucuna, Lupine, Canavalia and Crotalaria) as to their appropriate application methods in a farm, and notify coffee farmers as soon as the results becomes available. 2. To include in the coffee ISFM programme other plants with nutritive value, such as “tughutu” (Adhatoda engleriana), wild sunflower (Tithonia diversifolia) and fishbean (Tephrosia vogelii). 3. To carry out more research on the applicability of the model to all categories of coffee growers, with issues of shade-grown coffee, intercropped with staple food crops, etc. 4. To integrate the model to more generic agrometeorological models as climate change becomes more and more important in the coffee growing areas. 5. To establish the appropriate entry points in the inclusion of secondary macronutrients and micronutrients to the model and the way they influence the availability of N, P and K to coffee. 6. To collaborate with computer programming specialists and develop a full-fledged software for SAFERNAC.
Effect of liming acid soils on physico-chemical characteristics of the soils and coffee seedling vigor in Mbozi District, Tanzania
(Sokoine University of Agriculture, 2019) Mfaume, D. P.
Soil acidity is one of the most important soil factors affecting crop growth and ultimately yield and profitability of coffee in Mbozi District Tanzania. Soils tend to be naturally acidic in areas where rainfall is sufficient to cause substantial leaching of basic ions such as calcium and magnesium, which are replaced by hydrogen ions. Most soils in Mbozi District are acidic due to high rainfall and/or the use of soil acidifying fertilizers over a long period of time. Low soil pH causes aluminium and manganese toxicities while calcium, phosphorus and magnesium become deficient. In order to counteract the situation, liming is inevitable. This study was conducted on Ultisols of Mbimba sub- station, located in Mlowo Ward, Mbozi District, Songwe Region Tanzania. The study area is located within latitudes 9 0 05’35.97”S and 9 0 05’13.10”E and longitudes 32 0 57’14.51”E and 32 0 57’22.32”E. The area experiences mean annual rainfall ranging between 1 000 and 1 500 mm with a monomodal distribution pattern. The study aimed at increasing soil productivity for coffee through the use of agricultural lime and ultimately improve livelihoods of the coffee farmers in Mbozi District. Different levels of dolomite lime at 0 kgha -1 , 1 000 kgha -1 , 2 000 kgha -1 and 2 500 kgha -1 were used whereby NPK (22.6.12 +3S) at 150 kgha -1 was used at basal application rate. The field layout was set in a randomized complete block design with three replications. The results indicated that lime at 1 000 kgha -1 and 2 000 kgha -1 increased soil pH between 0.22 and 0.97 units and the increase of P was significant at P<0.001. Lime applied at a rate of 2 000 kgha -1 increased available P concentration by 5.73 - 7.28 mgkg -1 while exchangeable Potassium concentration increased by 0.14 - 6.01mgkg -1 in all 3 levels of lime and K increase was significant at P = 0.05. Soil Ca and Mg increased between 0.19 and 6.82 cmol(+)kg -1 and 0.54 - 1.98 cmol(+)kg -1 respectively after application of dolomitic lime. Plant height increased between 60.4 and 67.1 cm, branches between 29-31, internodes between 23 and 27, canopy width between 74.7 and 79.5cm and stem girth between 8.2 and 9cm. A very strong positive correlation was found between lime and Mg (R 2 = 0.8643), moderate positive correlation between lime and N (R 2 = 0.4453), between lime and P (R 2 = 0.7064), between lime and K (R 2 = 0.4043), between lime and Ca (R 2 = 0.5288) while weak correlation between lime and Na (R 2 = 0.2007. Correlation value of < 0.4 is considered as weak, 0.4 - 0.8 moderate correlation and 0.8˃ as very strong correlation. Thus, the study recommends the use of 2 000 kgha -1 of CaMg(CO 3 ) 2 lime to be used by Mbimba Mbozi farmers in coffee farms.
Effect of tillage, farmyard manure and potassium rates on the perfomance and profitability of cassava in selected districts of Kagera, Tanzania
(Sokoine University of Agriculture, 2022) Merumba, Mgeta Steven
In Tanzania cassava (Manihot esculenta, Crantz) is the second most important food security crop after maize. Its roots produce at least 30% of starch on dry weight basis, which is the major source of dietary energy, different industrial products like sugar, pharmaceutics, alcohol, textile products and animal feeds. In the Lake zone of Tanzania, cassava is grown in all regions, which account for 23.7% of the total cassava production in the country. Despite the importance of cassava in food systems there is decreasing yield. For example, the national average root yield is 10 MT ha -1 compared to the potential yields of 25 - 80 MT ha -1 , whereas in Kagera region, average yield in farmers’ fields is about 7.80 MT ha -1 . The low yield is due to, among others, increased susceptibility of the crop to cassava mosaic disease (CMD) and cassava brown steak disease (CBSD), declining soil fertility and poor agronomic practices. In the Lake zone, cassava is planted on ridges or on flat tillage but little information exists on the performance of cassava when planted on ridges or on flat tillage. In addition, cassava responds well to farmyard manure and inorganic fertilizers. But scant information exists on the performance of cassava upon use of different rates of FYM and potassium fertilizer, specifically based on Kagera region climate and soils. This study, therefore, aimed to determine the effects of tillage methods and application of different rates of FYM and potassium fertilizers on the performance and profitability of cassava in Bukoba, Missenyi and Biharamulo districts of Kagera region. The specific objectives of this study were to: (i) characterize and classify the soils of the study area and assess their suitability for cassava production, (ii) assess the current soil fertility status of farmers’ fields in the study sites, (iii) determine the effects of tillage methods, farmyard manure and potassium rates on soil moisture conservation and relationship with cassava root yield, (iv) determine the effects of tillage methods, FYM and potassium rates on cassava growth, yields and root quality, and (v) evaluate the economics of using farmyard manure and potassium fertilizer rates in cassava production in the study area. To achieve objective i, pedological characterization, which involved reconnaissance field survey in Bukoba, Missenyi and Biharamulo Districts was carried out. Soil profile description and soil sampling for laboratory analysis were done according to the FAO Guidelines for Soil Description. The soils of the study sites were classified to the family level of the USDA Soil Taxonomy and to tier-2 of the FAO World Reference Base for Soil Resources. Soil suitability assessment of the experimental sites was done using a simple limitation method based on the FAO Framework for Land Evaluation. The results revealed that the soils of Bukoba and Biharamulo sites had similar morphological properties, which were different from Missenyi site. But all differed in their physical, chemical and generic properties. Based on the USDA Soil Taxonomy, Bukoba and Biharamulo sites were classified as “Typic Kandiudults”.and as “Haplic Ferralic Acrisols”, and “Chromic Ferralic Acrisols” respectively according to FAO World Reference Base for Soil Resources. Missenyi site was classified as “Typic Endoaquolls” and “Fluvic Gleyic Phaeozems” according to USDA Soil Taxonomy and FAO World Reference Base for Soil Resources, respectively. Moreover, Missenyi and Biharamulo sites were evaluated as marginally suitable and the Bukoba site as moderately suitable for cassava production. Therefore, soil fertility management strategies are recommended in each studied site for optimum cassava yields. To achieve objective ii, two wards and one village in each ward were selected in Bukoba, Missenyi and Biharamulo districts. A total of thirty-three fields were selected (five farmers' fields in each village and one experimental field in each district). Composite soil samples at 0- 20 cm depth were taken using a using a zigzag pattern over the whole field's area and analyzed. Correlation analyses among soil chemical properties were performed using IBM SPSS Statistic 20 statistical package. Soil fertility index (SFI) and identification of limiting nutrients were used to assess the fertility status of selected farmers’ the fields. Results indicate that the studied fields had poor fertility to good fertility. Phosphorus and potassium deficiencies were widely spread in Bukoba district while N and S deficiencies were widely spread in Missenyi district and N, P and K deficiencies were widely spread in Biharamulo district. There were positive and negative and significant (p≤ 0.05) and highly significant (p≤ 0.01) correlations among the soil chemical properties in each district. Therefore, site specific soil fertility management practices are recommended based on limiting nutrients. To achieve objective iii, one cassava field trial was established in each selected district (Bukoba, Missenyi and Biharamulo) during 2018/19 and 2019/20 cropping seasons using the split-plot design. The treatments were arranged in Randomized Complete Block Design (RCBD) with three replications. Tillage methods (flat tillage, open ridging and tied ridging) were the main plots and fertilizer types and rates [farmyard manure (FYM) alone at 4 MT ha -1 or FYM alone at 8 MT ha -1 , nitrogen (40 kg N ha -1 ) + phosphorus (30 kg P ha - 1 ) + potassium at 40, 80 or 120 kg K ha -1 and the combination of FYM alone at 4 MT ha -1 or FYM alone 8 MT ha -1 + potassium at 40, 80 or 120 kg K ha -1 ] were the sub-plots. Soil moisture was monitored starting from 1 week after the last rain event at an interval of 2 weeks up to the first rain event of the following season. The soil samples in cores were weighed and placed in the drying oven at 105 o C to constant weight. The soil moisture content (%) in each soil sample was determined gravimetrically. The results showed that tie and open ridges conserved significantly (p≤0.05) more soil moisture ranging from 24 to 58% (Bukoba district), 10 to 45% (Missenyi district) and 10 to 32% (Biharamulo district) than flat tillage ranging from 22 to 43% (Bukoba district), 8 to 37% (Missenyi district) and 7 to 27% (Biharamulo district) in both cropping seasons. However, tied ridges conserved significantly (p≤0.05) more (11 to 58%) soil moisture than open ridges (10 to 47%) in the medium and high rainfall areas as opposed to the low rainfall area. The results also indicate that the use of FYM significantly (p≤0.05) conserved more soil moisture (16.54 to 63.48%) than inorganic N, P and K fertilizers (12.27 to 53.60%). In addition, use of FYM alone at 8 MT ha -1 conserved significantly (p≤0.05) more soil moisture (19.94 to 62.16%) than FYM alone at 4 MT ha -1 (16.80 to 58.33%). Moreover, there was a significant (p≤0.05) association between soil moisture conservation and changes in cassava root yields. Therefore, planting cassava on ridges together with use of high rates of FYM (8 MT ha -1 ) is indispensable for adequate soil moisture conservation and improving cassava root yields. To achieve objective iv, data on daily rainfall (mm) were collected in each experimental site. Data on root and biomass yields (MT ha -1 ) were collected from the net plot from established trials described in objective ii above. About 500 g of cassava roots from each treatment were peeled and oven dried at 105 o C to constant weight for determining dry matter content gravimetrically and root starch content in each treatment was determined. In addition, the post-harvest soil samples and cassava leaf samples were collected from the control plots and the plots that received the combination of FYM at 8 MT ha -1 and potassium (K) at 40 or 120 kg ha -1 for determining the concentration of Nitrogen, phosphorus and K and soil pH. The results indicate that planting cassava on ridges gave significantly (p≤0.05) higher (18.98 - 34.84 MT ha -1 ) cassava fish root yield than on flat tillage (16.86 - 29.74 MT ha -1 ). However, use of ridges or flat tillage did not show significant (p≤0.05) difference in starch and dry matter contents in cassava roots, soil pH, and concentration of N, P and K in the soil and cassava leaves and sprouting of cassava plant. Combined use of FYM at 4 MT ha -1 or FYM at 8 MT ha -1 and potassium at 40, 80 or 120 kg K ha -1 significantly (p≤0.05) improved cassava growth and increased cassava fresh root yields (14.56 - 39.94 MT ha -1 ). Also, combined use of FYM at 4 MT ha -1 or FYM at 8 MT ha -1 and potassium at 40, 80 or 120 kg K ha -1 ; significantly (p≤0.05) improved cassava growth and increased cassava fresh biomass yields (9.36 - 32.86 MT ha -1 ). Combined use of FYM at 8 MT ha -1 and potassium at 120 kg K ha -1 or FYM at 8 MT ha -1 and potassium at 40 kg K ha -1 increased the concentration N, P and K in the soil and N and K in cassava leaves. Therefore, planting cassava on ridges and combined use of FYM at 4 MT ha -1 and potassium at 80 or 120 kg K ha -1 is desirable for improving cassava growth, increasing biomass and root yields and increasing root quality. Combined use of farmyard manure at 8 MT ha -1 and potassium at 120 kg K ha -1 is desirable for increasing the concentration of N and K in the soil and in cassava leaves. However, for the resource-poor farmers who cannot afford the high rate of K, combined use of farmyard manure at 8 MT ha -1 and potassium at 40 kg K ha -1 can be used. To achieve objective v, yields data collected from the established trials as described in objective iii above were used to perform partial budget analysis, whereby, the gross values were estimated using the adjusted yields at market price for cassava and fertilizers. Costs and benefits were calculated on a hectare basis. All variable costs were summed up to give total variable cost (TVC). Thereafter, the net benefits (NB) ha -1 of the tested treatments were calculated and used to assess the profitability of each treatment. In addition, benefit- cost ratios (BCR) of the tested treatments were compared to the acceptable value of greater than 2 for the technology to be adopted by farmers. The results indicate that in both cropping seasons, and at all studied sites, all tested fertilizer rates gave acceptable BCR of greater than 2, implying that all the fertilizer types and rates tested in this study could be used in cassava production in the study areas. In addition, the results on net benefit indicate that use of combination of FYM at 8 MT ha -1 and potassium at 80 kg K ha -1 gave higher net benefit than the other fertilizer types and rates, and is therefore, desirable for increasing cassava root yield and economic benefit in the study area. However, for the resource-poor farmers, combined use of farmyard manure at 8 MT ha -1 and potassium at 40 kg K ha -1 can still be adopted in the study area because, for some reason, not all the famers can afford the best treatment. The major conclusions drawn from this study are that the soils of Bukoba and Biharamulo sites have similar morphological properties, which are different from Missenyi site. However, all soils differ in their physical, chemical and generic properties. According to the USDA Soil Taxonomy, the soils of both Bukoba and Biharamulo sites were classified as “Typic Kandiudults” and as “Haplic Ferralic Acrisols” and “Chromic Ferralic Acrisols”, respectively, according to FAO World Reference Base for Soil Resources. The soil of Missenyi site was classified as “Typic Endoaquolls” according to USDA Soil Taxonomy and as “Fluvic Gleyic Phaeozems” according to FAO World Reference Base for Soil Resources. Missenyi and Biharamulo sites were both evaluated as marginally suitable while Maruku site was evaluated as moderately suitable for cassava production due to soil fertility constraints and hence sustainable cassava production in these areas would need interventions for soil fertility improvement. The soil fertility status of the studied fields ranged from poor fertility to good fertility whereas, P and K deficiencies were widely spread in Bukoba district while N and S deficiencies were widely spread in Missenyi district and N, P and K deficiencies were widely spread in Biharamulo district. Use of ridges conserved more soil moisture than use of flat tillage, and use of farmyard manure at 8 MT ha -1 conserved more soil moisture than combined use of inorganic N, P and K fertilizers or use of farmyard manure at 4 MT ha -1 . Moreover, plating cassava on ridges together with combined use of FYM at 4 MT ha -1 and potassium at 40, 80 or 120 kg K ha -1 improved cassava growth and increases cassava root and biomass yields than use of flat tillage together with the same fertilizer rates. Combined use FYM at 8 MT ha -1 and potassium at 80 or 120 kg K ha -1 or combined use of inorganic N at 40 kg ha -1 , P at 30 kg ha -1 and K at 120 kg ha -1 increased the contents of starch and dry matter in cassava roots and combined use of FYM at 8 MT ha -1 and potassium at 40 80, or 120 kg K ha -1 increased concentration of N, and K in the soil and cassava leaves. In terms of profitability, combined use of FYM at 8 MT ha -1 and potassium at 80 kg K ha -1 gave higher net benefit than the other fertilizer types and rates tested in this study and is therefore, desirable for increasing cassava root yield and economic benefit in the study area. However, for the resource-poor farmers, who cannot afford the best treatment, combined use of farmyard manure at 4 MT ha -1 and potassium at 80 kg K ha -1 can still be adopted.
Effect of water management systems with different nutrient combinations on performance of rice on soils of Mvumi, Kilosa district, Tanzania
(Sokoine University of Agriculture, 2016) Massawe, Ikunda Herman
A comprehensive study was conducted on soils of Mvumi Village, Kilosa District, Tanzania to investigate the effect of water and nutrients on the growth and yield of rice so as to improve rice production by manipulating water and nutrients. Soil characterization, fertility evaluation and pot experiment were conducted. The soils of the study area were classified respectively as Ustic Endoaquerts and Haplic Vertisols in the USDA Soil Taxonomy, and World Reference Base for Soil Resources. Nitrogen (N), Phosphorus (P) and Potassium (K) were deficient in all sampled fields whereas micronutrients were adequate except for Zn which was low. A pot experiment was set to test the effect of water and nutrients on performance of rice. The experiment was laid in a split plot design with two water management systems (SRI= Alternate wetting and drying, FLD= Continuous flooding) as main factor and five nutrient combinations (N0P0K0S0, N400P0K0S0, N400P80K0S0, N400P80K50S0, N400P80K50S40) as sub-factor. Nutrients and water had significant effect on growth, yield and nutrient content of rice. Overall, treatment N400P80K50S40 had significantly (P < 0.05) higher number of tillers (12.44 tillers plant-1), plant height (98.86 cm), grain yield (26.26 g plant-1) and biomass yield (23.57 g plant-1) as well as total P (0.27%), K (1.07%) and S (0.15%) concentrations in biomass shoot than other treatments. On the other hand, the highest number of tillers (11 tillers plant-1), grain yield (20.74 g plant-1), biomass yield (17.37 g plant-1) and S (0.13%) concentration in biomass shoot were recorded in SRI while the highest plant height (95.47 cm), N (2.02%), P (0.24%) and K (0.89%) concentrations in biomass shoot were recorded in FLD. The results of interaction of nutrients and water showed that, grain yield increased significantly (P < 0.05) from 4.71 g plant-1 to 27.37 g plant-1 in FLD + N0P0K0S0 and SRI + N400P80K50S40 , respectively.
Effectiveness and performance of indigenous soil and water conservation measures in the west Usambara mountains, Tanzania
(Sokoine University of Agriculture, 2015) Mwango, Sibaway Bakari
The West Usambara Mountains in Tanzania are severely affected by soil degradation caused by water erosion that includes rill, interill, gully and landslides. To a large extent the area is also affected by soil degradation that is caused by declining soil fertility and harvesting of tuber, bulb and root crops. The problem of soil degradation in the area has triggered adverse effect on crop productivity and is a serious threat to livelihood. Many scientific „Soil and Water Conservation‟ (SWC) measures such as bench terraces, Fanya Juu terraces, cut off drains, contour strips and agroforestry have been promoted in the area to combat the escalating problem of soil degradation. However, these technologies were rejected or minimally adopted because most of them were laborious and expensive. In the West Usambara Mountains, farmers have their own local SWC measures such as miraba (rectangular grass bound strips that do not necessarily follow contour lines), micro ridges and stone bunds, technologies which unfortunately have received very little considerations. Miraba is the most preferred and widely practised indigenous SWC measure in the West Usambara Mountains because it is cheaper in implementation and provides fodder for livestock. Despite all the efforts in combating soil degradation, little success has been achieved as the process has been active even in places where SWC measures are practised. The general objective of the current study was to enhance knowledge on indigenous SWC measures under smallholder farming conditions for preventing soil degradation and improving crop yields in the West Usambara Mountains. Specifically the study aimed to i) evaluate potentials and constraints of indigenous SWC technologies for minimizing soil degradation and enhancing crop yields in various landscape types in farmers‟ fields ii) determine the effectiveness and performance of selectediii indigenous SWC measures for improved crop yields and iii) investigate the mass of soil and nutrient losses due to crop harvesting under different indigenous SWC measures. The study was conducted in Majulai and Migambo villages in Lushoto District, Tanzania. The studied villages belong to two major contrasting agro- ecological zones of the West Usambara Mountains. The former village belongs to dry warm and the latter to the humid cold agro-ecological zone. Participatory Rural Appraisal (PRA) coupled with soil fertility and crop yield surveys under various SWC technologies in farmers‟ fields were conducted. Low soil fertility and spatial variability of soil fertility were revealed as major constraints to high crop yields under miraba. Thus, miraba were integrated with mulching and spacing of grass strips adjusted to rectify the observed constraints such that i) the spacing of grass strips that form miraba across the slope was reduced from traditionally very wide (10 m - 30 m apart depending on the size of the farm plots) to 5 m apart to mimic the recommended maximum width of hand made bench terraces; and ii) mulching applications using leaves of readily available plants namely Tithonia (Tithonia diversifolia) and Tughutu (Vernonia myriantha). These plants are also reported to have appreciable contents of N, P and K. The effectiveness and performance of miraba that were adjusted to 5 m and with above-mentioned mulching materials were tested in runoff experiments that were set in Majulai and Migambo villages, in which climatic data were also collected using standard rain gauges and tipping bucket rain gauges. Furthermore, root properties of Guatemala grass (Tripsacum andersonii), Napier grass (Pennisetum purpureum) and Tithonia shrub (Tithonia diversifolia) were investigated in farmers‟ fields and theiriv erosion-reducing effects predicted. Since these plants are used for establishing miraba and stabilizing the edge of bench terraces, it was deemed rational to investigate the erosion-reducing potential of their roots since during drought or fire outbreak, the above biomass disappears but roots remain and these could significantly contribute to reduction of soil runoff. A survey was also conducted in farmers‟ fields to investigate the magnitude of soil and nutrient losses resulting from harvesting of root, tuber and bulb crops under miraba. The aim was to determine the magnitude and effect of this process on soil degradation and extent to which it may contribute to frustrate soil conservation efforts in the area. The results of the current study showed that: at 5 m spacing of miraba grass strips, there was formation of progressive bench terraces which significantly demonstrated their effectiveness in controlling soil erosion in the West Usambara Mountains. Formation of progressive bench terraces as a result of miraba implementation is by far cheaper than mechanical construction of bench terraces which is not favoured by farmers due to the labour costs that are involved. The roots of Guatemala grass had higher (p < 0.05) potential to reduce soil erosion rates by concentrated flow than Napier grass and Tithonia shrub in the 0-40 cm soil depth. These findings have implications on the selection and use of appropriate plants for soil erosion control. Soil loss was significantly (p < 0.05) higher in cropland with no SWC measure than under miraba with mulching (e.g. 184 Mg ha -1 yr -1 vs. 8 Mg ha -1 yr -1 ). The annual nutrient losses (kg ha -1 yr -1 ) were higher (p < 0.001) in croplands with no SWC measures (e.g. 307, 0.8, 14 NPK) than under miraba with mulching (37, 0.1, 4.0 NPK respectively). Soil fertility was higher (p < 0.05) under miraba with Tughutu than under miraba with Tithonia and miraba sole. Similarly, maize and bean yieldsv (Mg ha -1 ) followed the same trend e.g. 3.8 vs. 1.6 for maize and 1.0 vs. 0.6 for beans under miraba with Tughutu mulching vs. cropland with no SWC measures respectively. The crop yields did not vary between segments under miraba or miraba with mulching, whereas, under cropland with no SWC measures, maize yields differed significantly (p < 0.05) with lower position segments having higher yields than the upper position segments. Climatic conditions had an influence on the effectiveness and performance of miraba such that miraba were found more effective in Migambo village which is humid than in Majulai village which has drier climate. During dry spells, Napier grasses forming miraba were found to die out and rejuvenate during the rainy seasons, hence the formed Napier grass strips become weaker and less effective. On the other hand, soil loss due to crop harvesting (SLCH) under miraba was significantly (p < 0.05) higher for carrot 7.1 than 3.8 for onion and 0.7 Mg ha -1 harvest -1 in the case of potato harvesting. Soil nutrient losses in kg ha -1 harvest -1 were higher (p < 0.05) for carrot than for onion and potato harvesting. Soil water content at harvest time played a significant role at 5 % level in inducing SLCH for onion crop. Bulk density and soil texture played only a minor role to SLCH of the studied crops. These observations imply that soil degradation due to crop harvesting under miraba is substantial and poses a challenge that calls for immediate attention on the harvesting practices. Based on the findings, it is concluded that i) low soil fertility and spatial variability of soil fertility and crop performance under traditional miraba and micro ridges are the major constraints to high crop yields in smallholder farmlands of the West Usambara Mountains. ii) soils of the West Usambara Mountains are susceptible to erosion as indicated by their very low values of K factors and very high rates of soilvi degradation by water erosion. iii) roots of Guatemala grass are more effective in reducing concentrated flow erosion rates in the 0 - 40 cm soil depth than the roots of Napier grass while the roots of Tithonia shrub are the least effective. Thus selection of plants with effective rooting characteristics for controlling concentrated flow erosion is important. iv) improved miraba are effective in reducing runoff, soil and nutrient losses, but, improved miraba with either Tithonia or Tughutu mulching were more effective. v) Tughutu mulches had higher potential in soil fertility restoration than Tithonia mulches; and thus improved miraba with Tughutu mulching was the best SWC measure for improving crop yields. vi) although miraba and miraba with mulching were effective in reducing soil and nutrient losses, significant rates of soil and nutrient losses under miraba that were revealed due to harvesting of root, tuber and bulb crops could frustrate the success of soil conservation efforts that have been achieved. The following recommendations are made: i) due to the vulnerability of the West Usambara Mountains to soil degradation, it is recommended not to cultivate in these areas without the use of appropriate SWC measures. ii) in dry areas such as Majulai village drought resistant grasses such as Guatemala should be used for establishing miraba because Napier grasses mostly preferred are sensitive to drought, thus leading to reduced effectiveness of miraba. iii) the spacing of miraba grass strips across the slope is recommended at 5 m apart for effectively controlling spatial variability of soil fertility and crop yields and for allowing miraba to form progressive bench terraces that are effective in controlling soil erosion in the West Usambara Mountains. iv) the use of Tughutu shrub should be strongly promoted for use as mulching materials under miraba as the shrub has demonstrated itsvii effectiveness in controlling soil erosion and at the same time improving soil fertility and crop yields. v) furthermore, Tughutu shrubs should be planted along the borders of farm plots so that the plants can easily be available for use as mulching materials. vi) farmers should remove as much as possible soil stuck on the harvested crops at their farm plots to avoid losses of soil and nutrients from farm lands. vii) further studies should be carried out on the scaling up of the application of improved miraba in other areas not only in the West Usambara Mountains but also in other areas of the country with similar socio-economic and environmental conditions for reduced soil degradation and improved crop productivity. viii) the potentials of the studied mulching materials should be tested for the productivity of vegetables such as cabbage, tomatoes, onions and carrots which are widely cultivated in the West Usambara Mountains. ix) further research should be carried out to investigate the effectiveness of the studied soil conservation practices on watershed protection to mitigate river stream sedimentation. x) more studies should be carried out to investigate SLCH for other crops in different climatic conditions and soil types tovalidate further this process under low input farming.
Effects of commercial chemical and microbiological products in soil on maize growth and yields
(Sokoine University of Agriculture, 2015) Kiriba, Deodatus Stanley
A study was conducted under screenhouse and field conditions at Sokoine University of Agriculture to evaluate the effects of commercial chemical and microbiological products on growth and yields of SITUKA maize variety grown on an Ultisol soil. The study soil had medium organic matter, low available phosphorous (1.02 mg/kg) and very low extractable zinc (0.34 mg/kg) hence the soil was of medium fertility status and only moderately suitable for maize production. Commercial products evaluated were Teprosyn, P-solubilizers and N 2 -fixers, in each experiment using the randomized complete block design (RCBD) with three replications. Six treatments, namely: i.control (without commercial product and P- fertilizer), ii.commercial product alone at manufacturer’s recommended rate, iii.commercial product alone at double rate, iv.commercial product + 10 kg P ha -1 P-fertilizer, v.10 kg P ha -1 P-fertilizer and vi.20 kg P ha -1 P-fertilizer, were used. In the screenhouse, Teprosyn, P- solubilizers and N 2 -fixers did not result in significantly (P<0.05) different growth performance or biomass yields relative to those in the control. However, these products in combination with P-fertilizer (at half recommended rate) resulted in significant (P<0.05) increase in growth parameters and biomass yields. Teprosyn increased biomass yields from 0.96 g/plant (Control) to 1.89 g/plant (K 2 HPO 4 at 20 kg P ha -1 ), P-solubilizers from 1.01 g/plant (Control) to 1.71 g/plant (K 2 HPO 4 at 20 kg P ha -1 ) and N 2 -fixers from 0.95 g/plant (Control) to 2.19 g/plant (K 2 HPO 4 at 20 kg P ha -1 ). Under field experimentation, Teprosyn, P-solubilizers and N 2 -fixers had no significant (P<0.05) effect on maize growth performance. Only the P-solubilizers, either alone or in combination with P-fertilizer, produced significantly (P<0.05) higher grain yields than the control increasing grain yields from 2.04 t ha -1 (Control) to 3.53 t ha -1 (YaraMila Cereal at 20 kg P ha -1 ). It is recommended that Tanzania fertilizer regulatory authority should require manufactures to improve the quality standards of before the commercial products are accepted in the country and they should further be tested in other P-deficient soils.
Effects of copper concentration in soil on prolife ration and survival of rhizobia, nodulation and biological nitrogen fixation in beans, cowpeas and soybeans
(Sokoine University of Agriculture, 2010) Tindwa, H
A study was conducted in which two strains of the fast – growing bean rhizobia- PV 1 and PV 2 and two others of the slow – growing bradyrhizobia for cowpeas and soybean- CP 1 & GM 8 , respectively, were used to test their ability to: - (a) proliferate in copper contaminated liquid media, (b) survive in copper contaminated soil, (c) nodulate respective host legumes and (d) fix nitrogen under increasing copper levels both in vitro and in vivo. Known population sizes of each of the strains were exposed to copper concentrations in the range: 0, 20, 40 60, 80 and 100 ppm in either Yeast - extract Mannitol Broth or in modified Leonard Jar assemblies or potted soil. Most Probable Number (MPN) studies were also done to estimate populations of the native strains of the fast - and slow - growing rhizobia in a Cu -contaminated soil. Results indicated that copper was more toxic to the slow – growing bradyrhizobia than to the fast – growing rhizobia. Reduction in population sizes in vitro was more significant (p = 0.05) for bradyrhizobial than for rhizobial strains. Reductions in fresh nodule volume, fresh nodule mass and total shoot nitrogen were more significant (p = 0.05) in the bradyrhizobial – than in rhizobial – legume associations. Copper depressed the populations of slow – growing strain CP 1 and GM 8 in vivo more than those of the fast – growing strains PV 1 and PV 2 . There was no statistically significant (p = 0.05) effect of 82.5 mg Cu/kg soil on numbers (MPN) of native rhizobial strains, probably due to adsorption of Cu by soil colloids. This study showed that based on the solution culture, potted soil and soil survival experiments, slow - growing rhizobia were more susceptible to Cu toxicity than were the fast - growing rhizobia.
Effects of flooding and system of rice intensification on nitrogen use efficiency in rice production at Mkindo, Morogoro, Tanzania
(Sokoine University of Agriculture, 2016) Eliya, J.
An experiment was conducted in a glasshouse in 2016 at Sokoine University of Agriculture Morogoro Tanzania to study the effects of system of rice intensification (SRI) and flooding on Nitrogen Use Efficiency (NUE) for the lowland rice ecosystem. The soil used in the experiment was Eutric fluvisol and was analysed in the laboratory to evaluate soil fertility status. The soil was observed to have some plant nutrient below the critical range like N, 0.09%; K, 0.2 cmol kg-1;P, 4.13 mg/kg and OC, 1.23%. The experimental design was split-plot in randomized complete block design with four replicates.The main plot constituted two water management systems viz. SRI and flooding. Subplot treatments were nitrogen levels viz; 0, 125, 250 and 500 mg N kg-1 of soil. Rice variety used was SARO 5 (TXD 306) which is the improved rice variety adapted for lowland irrigated ecosystem. Analysed data for rice grain yield, Nitrogen Use Efficiency (NUE), dry matter yield and plant height did not show a significant difference (P< 0.05) due to the influence of SRI and flooding water management systems, whereby SRI yield ranged from 3.6 – 30.9 g grain yieldpot-1 and flooding was 5.9 – 25.0g grain yield pot-1. NUE ranged from 38.1- 66.1 mg grain mg-1 N for flooding and 54.8-85.7 mg grain mg-1 N. For SRI and flooding, the study confirmed that there was no significant difference (P< 0.05) on rice yield and NUE. The significant P< 0.05) difference on grain yield, NUE, dry matter and N concentration on rice plant was due to the effect of nitrogen application rates. The grain yield under SRI and flooding water management system ranged from 3.6 – 30.9 g pot-1 and 5.9 – 25 g pot-1 respectively.