Department of Soil and Geological Sciences

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Agronomic evaluation of some industrial wastes as alternative sources of plant nutrients in Morogoro District, Tanzania
(Sokoine University of Agriculture, 2001) Ndaki, Stephen Mhoja Mashauri
A study’ was conducted at Magadu. Morogoro. Tanzania to evaluate the industrial wastes as alternative sources of plant nutrients and/or soil conditioners. The soil of Magadu was classified by Kaaya (1989) as Oxic Haplustult. The soil was characterised in this study for its physical and chemical properties prior to planting of the test crop. The analytical data showed that the soil was strongly acidic with a pH of 5.1. Total N. available P. %OC, exchangeable Ca and Na. CEC. and DTPA extractable Zn were in the low range. Exchangeable Mg was in the medium range, while exchangeable K. DTPA extractable Fe, Mn and Cu were high. In the field a randomised complete block design was used to evaluate the wastes using maize as test crop. The rate of waste application were 5.24 4.8, 4.25, 4.5 and 3.7 tonnes/ha of waste tea, wattle bark chippings, waste tobacco, wood ash and saw dust respectively. Prior to soil incorporation, the wastes were analysed for their chemical properties. Maize dry matter yields were significantly higher in plots which received 5.24 tonnes/ha of waste tea followed by plots which received 4.25 and 4.5 tonnes/ha of waste tobacco and wood ash respectively. Maize grain yields were significantly higher in waste tea and wattle bark chippings amended plots than in the other waste amended plots. At the end of the growing season the soil was analysed to evaluate the residual effect of wastes on soil properties. Soil pH, available water capacity, available P, % OC, total N, exchangeable bases, CEC, DTPA extractable Zn and Cu in waste amended plots increased in the top 15 cm of soil relative to the control plots. DTPA extractable Fe and Mn, exchangeable Al and acidity were significantly reduced in all waste treatments. Total N and % OC in wood ash and saw dust amended plots were at par with those found in control plots. The results from the field suggested that when applied at agronomic rates, industrial wastes can produce satisfactory plant growth and yields. The results revealed further that waste application on a long term basis will allow good build up of soil organic matter and plant nutrients which in turn will improve on soil productivity. It is recommended that N supplement to wood ash which is rich in almost all macro and micronutrients (except N) would balance its nutrient supply to plants. A glasshouse decomposition experiment was carried out with some wastes including sawdust and wattle bark chippings in perforated plastic litter bags. The wastes were either surface applied or buried to 10 cm depth in wooden troughs. The decomposition process which was monitored at 0. 3, 6, 9, and 12 weeks of incubation revealed that soil incorporated wastes decomposed and released nutrients faster than surface applied ones.
Agronomic management strategies for adaptation to the current climate variability: the case of North-Eastern Tanzania
(2014) Tumbo, Siza D.; Rwehumbiza, Filbert B.; Kahimba, Frederick C.; Enfors, Elin; Mahoo, Henry F.; Mbilinyi, Boniface P.; Mkoga, Zacharia; Churi, Ayubu
Rainfed agriculture in semi-arid areas of sub-Saharan Africa faces a great challenge due to increasingly high variability and unreliability of rainfall. Two of the effective adaptive responses to reduce the vulnerability to the changing climate are through use of soil and water conservation technologies and employment of improved agronomic practices. A study was conducted to quantify the risk and profitability of agronomic management strategies for maize using long-term climatic data and a crop simulation model. APSIM model was used to perform long-term simulations of different management strategies. Simulated maize grain yield for different cultivars and sets of management strategies were evaluated to establish the associated risks and benefits. Results indicate that planting Situka or SC401 during Masika season instead of Kito or other cultivars, gives a yield of more than 1 ton/ha under conventional methods. Maize yield increases to 2t/ha or even higher with the use of fertilizers and recommended management practices. The cost benefit analysis indicated that income greater than USD 700 per ha could be obtained when recommended practices are applied, with Situka and SC401 as the maize varieties planted. Based on the results of the study, it is recommended that farmers should employ improved agronomic management practices only when the seasonal forecast indicates above normal rainfall. The early availability of seasonal rainfall forecast is thus vital. Alternatively, farmers are much safer if they continue to employ their conventional approaches of farming because these have lower risks.
Anthropogenic soils and land use patterns in relation to small mammal and flea abundance in plague endemic area of Western Usambara Mountains, Tanzania
(Tanzania Journal of Health Research, 2014-07) Kimaro, D. N.; Msanya, B. M.; Meliyo, J.; Hieronimo, Proches; Mwango, Sibaway; Kihupi, N. I.; Gulinck, Hubert; Deckers, Jozef, A.
Heterogeneity in the landscapes of West Usambara Mountains on land use and human activities has been reported. However, the interface of land use patterns and human modified soils with small mammal and flea abundance for possible explanation of plague has not been explored. This study was carried out to determine the link between anthropogenic soils and land use patterns on small mammal and flea abundance and the occurrence of reported plague in the Western Usambara Mountains in Tanzania. Standard soil survey methods were used to identify and describe soils and land use patterns on lower slopes and valley bottoms on which the surrounding villages are reported to have high and medium plague frequencies. The identified soils were characterised in terms of their morphological and physico-chemical properties and classified according to FAO-World Reference Base for Soil Resources. Small mammals were trapped on the same landscape positions and identified to genus/species level. Fleas were removed from the trapped small mammals, counted and identified to species level. In total 57 small mammals were captured from which 32 fleas were collected. Results show that human settlements and mixed cultivation on lower slopes and continuous vegetable cropping in the valley bottoms are dominant land use types. Intensive use of forest soils, manuring and irrigation on farms in the studied landscapes have contributed to the development of uniquely human modified soils namely Hortic Anthrosols in the lower slopes and Plaggic Irragric Hortic Anthrosols in valley bottoms. The identified anthropogenic soils and land use patterns are associated with high abundance of small mammals (Mastomys natalensis) and flea species (Xenopsylla brasiliensis and Dinopsyllus lypusus). This phenomenon is vividly apparent in the villages with medium to high plague frequencies. The study suggests that plague surveillance programmes should consider the existing relationship between anthropogenic soils, land use patterns, small mammal and flea abundance.
Assessing drivers of soil properties and classification in the West Usambara mountains, Tanzania
(Elsevier, 2017-10-16) Massawe, B. H. J.; Winowiecki, L.; Meliyo, J. L.; Mbogoni, J. D. J.; Msanya, B. M.; Kimaro, D.; Deckersf, J.; Gulinck, H.; Lyamchai, C.; Sayula, G.; Msokah, E.; Vagen, T.; Brush, G.; Jelinskii, N. A.
Improved soil information in tropical montane regions is critical for conservation, sustainable agricultural management, and land use planning, but is often challenged by topographic and land-use heterogeneity. The West Usambara mountains are a part of the Eastern Arc chain of mountains of Tanzania and Kenya, a globally important tropical montane ecoregion made up of isolated fault-block mountain complexes characterized by high biological endemism, population density, and agronomic productivity. We synthesized novel and legacy soil data from published and unpublished studies to better understand the drivers of soil property distributions and soil diversity in the West Usambaras, and to serve as a foundation for improved soil mapping efforts across the Eastern Arc. Analysis of the resulting dataset of 468 sites (ranging in elevation from 1040 to 2230 m.a.s.l.) revealed that soil properties varied more significantly by land use and topography than by soil type, suggesting that future mapping efforts in the region should focus primarily on soil property prediction and secondarily on soil classification. Sites under cultivated land uses had the lowest topsoil soil organic carbon (SOC) concentrations and highest pH values, and SOC generally increased with increasing elevation. Valley soils had significantly lower surface SOC concentrations but higher exchangeable bases and pH values than all other landscape positions. Soil pH decreased by an average of 3.5 units across the entire elevation gradient and decreased by 1 unit with elevation even after SOC, land use and landscape position were included in multiple regression models. The relationship of cation exchange capacity (CEC) to SOC and clay content varied by landscape position. Therefore, particularly in montane regions where soils can vary significantly over short distances, multiple functions may be necessary to produce improved estimates of parameters such as CEC. Soil classification was driven most strongly by topography, with Acrisols (WRB Reference Group) and Ultisols (U.S. Soil Taxonomy (ST)) as the dominant soil types, located primarily on mid slope, upper slope and crest landscape positions, making up 47% and 75% of observed profiles, respectively. However, five ST Orders and seven WRB Reference Groups were present in the dataset, with the highest soil diversity occurring at lower slope landscape positions. Conclusions drawn from this large dataset support previous work in the West Usambaras and provide a conceptual foundation from which to build improved soil maps across the Eastern Arc and in other tropical montane systems throughout the world.
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 nutrient and biomass yield of medium and long duration pigeon pea in a pigeon pea-groundnut intercropping system in Malawi
(Journal of Sustainable Society, 2013) Phiri, Austin Tenthani; Msaky, John J.; Mrema, Jerome; Kanyama-Phiri, George Yobe; Harawa, Rebbie
Preliminary assessment of the performance of the medium and long duration pigeon pea in a pigeon pea- groundnut intercropping system was conducted at Chitedze Agricultural Research Station (S 13 0 59’ 23.2”, E033 0 38’ 36.8”) in the 2011/2012 cropping season. An experiment involving eight treatments replicated three times in a randomized complete block design was established. Two pigeon pea varieties, long (ICEAP 04000) and medium duration (ICEAP 00557) and groundnut (CG 7) were grown as monocultures and intercrops. The intercrops involved planting either of the pigeon pea varieties with groundnut. Baseline soil data indicate that the soil pH was acid to moderately acid both in the top (mean=5.4-5.7) and the sub soil (mean=5.4-5.6) in all the treatment plots, with mostly low to marginally adequate total nitrogen content both in the top (mean=0.08- 0.14%) and the sub soil (mean=0.09-0.13%). The soil organic carbon content was medium in the top soil (mean=0.9-1.6%) as well as sub soil (mean=1.1-1.6%) across the treatment plots. At the same time soil phosphorus was low to marginally adequate in the top soil (mean=16.8-27.6 mg kg -1 ) and marginally adequate in the sub soil (mean=20.8-25.6 mg kg -1 ), suggesting low soil fertility. The assessment of the above ground groundnut biomass indicate a mean yield range of 479-656 kg ha -1 . While the assessment of the total biomass yield of the pigeon pea varieties indicate a mean yield range of 2,034-2,593 kg ha -1 . In terms of estimated nitrogen yields returned to the soil, the medium duration pigeon pea-groundnut intercrop (mean=50.6 kg N ha -1 ) and the long duration pigeon pea-groundnut intercrop (mean=49.6 kg N ha -1 ) gave significantly (p<0.05) higher yields than by the monocultures of long duration pigeon pea (mean=41.1 kg N ha -1 ) and medium duration pigeon pea (mean=41.0 kg N ha -1 ). Statistically (p<0.05), the lowest amount of estimated nitrogen yield was generated by the groundnut sole crop (mean=12.8 kg N ha -1 ). Overall, the intercrops showed yield advantage (total LER >1.0) compared with the monoculture on equal land area. For the Malawian smallholder farmers, this suggests that mineral N supplementation in a legume-cereal rotation system for enhanced crop productivity might be less in the double legume-cereal rotation mode than in a legume monoculture-cereal rotation system.
Assessment of soil fertility status for Bambara Groundnut Production in South-eastern Tanzania
(IJPSS, 2018-09-13) Tenga, J. J.; Semoka, J. M. R.; Msanya, B. M.
Intensive farming practised in the agro-ecological zones of Makonde plateau (C2) and Inland plain (E5) of south-eastern Tanzania without proper soil management has led to nutrient depletion. The objective of the study was to assess the fertility status of soils in Bambara groundnut growing areas of south-eastern Tanzania. Twenty-two farmers' field sites were sampled and composite samples of top soil at 0 – 20 cm depth were collected for physical and chemical analysis. The results indicate that the soils in the study area are sandy loam (64%), loamy sand (27%) and sandy clay loam (9%). About 28% of the soils in the study area had very low CEC values (< 6 cmol (+) kg soil). Soil pH was strongly acidic to moderately acidic (≤ 5.5) and slightly acidic (≥ 6.0) in the C2 and E5 agro- ecological zones, respectively. Total N was very low (< 0.1%) and organic carbon was very low to low (< 0.6%). Low levels of available P (<10 mg/kg), inadequate S (SO 4 -S) levels (< 10 mg/kg) were observed. The exchangeable K in the C2 zone was very low to low (< 0.05 cmol(+)/kg) while E5 zone had medium K level. The calcium level of C2 was low to medium (0.2 – 2.5 cmol(+)/kg) 2+ whereas that of E5 was medium to high (0.6 – 5.0 cmol(+)/kg). The exchangeable Mg levels were + very low to low (< 0.2 cmol(+)/kg) while Na was < 0.30 cmol(+)/kg soil indicating no sodicity problem. For > 90% of the studied soils extractable Zn was below critical level of 0.6 mg/kg. All soils had adequate extractable Fe whereas > 70% of the soils had high (> 5 mg/kg) extractable Mn. The study area generally indicated low fertility status in terms of N, P, K, S, Mg and Zn, calling for proper management for improving crop production.
Assessment of soil N, P, and K status of selected paddy growing areas of Tanzania
(2000) Semoka, J.M.R.; Mnguu, Y.O.
Suitable diagnostic criteria to assess the N, P and K status of rice growing areas particularly in developing countries like Tanzania are required. The objective of this study was to develop such criteria in selected rice growing areas of Tanzania and relate nutrient levels to rice response to fertilizer appli cation; Soil samples from 10 paddy growing areas of Tanzania were testedfor N, P and K using selected indices. Nitrogen supply was assessed by organic carbon (OC), total Nand alkaline-KMn04-N while P was assessed by Olsen, Bray-1 and the iron oxide coated-filter paper strip (Pi) methods. Potassium was extracted by neutral 1 N NH40Ac. Extractable nutrients were correlated with DM Yields and nutrient uptakefrom a glasshouse experiment which was also used to assess response of rice to these nutrients. OJ the three Nindices evaluated, only OC correlated significantly (r = 0.73, P< 0.05) with n'ce DMyield thus serving as a good index of N supply. Asfor P indices, Olsen P gave a highly significant correlation with rice DM yield (r = 0.85, P < 0.01) while the relationships with the other two methods gave lower correlation coefficients. All the soils tested were deficient in N and thus no criticallevelfor N could be established while six soils out of 10 were deficient in P. The critical soil P level for Olsen method was estimated to be 20 mg Ikg. The extracted K values were all found to be higher than critical values established elsewhere. Therefore; Nand P are important constraints to rice production in Tanzania and appropriate recommendations should be drawn and demonstrated to farmers.
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.
Available technologies to replenish soil fertility in East Africa
(Springer, 2006) Semoka, J. R. M; Okalebo, J. R; Othieno, C. O; Woomer, P. L; Karanja, N. K; Bekunda, M. A; Mugendi, D. N; Muasya, R. M; Bationo, A; Mukhwana, E. J
Low inherent soil fertility in the highly weathered and leached soils largely accounts for low and unsu- stained crop yields in most African countries. But in particular, the major nutrients, nitrogen (N) and phosphorus (P), are commonly deficient in these soils. This scenario of nutrient depletion is reflected in food deficits and hence the food aid received continuously, specifically in sub-Saharan Africa. Undoubtedly, substantial efforts have been made in the continent to replenish the fertility of degraded soils in attempts to raise crop yields, towards self-sufficiency and export. Such efforts consist of applications of both organic and inorganic resources to improve the nutrient status of soils and enhanced nutrient uptake by crops, provided that soil moisture is adequate. Overall, positive crop responses to these materials have been obtained. Thus in the East African region, maize (staple) yields have been raised in one growing season from below 0.5 t/ha without nutrient inputs, to 3–5 t/ha from various nutrient amendments at the small- hold farm level. However, in spite of the positive crop responses to nutrient inputs, farmers are generally slow to adopt the soil fertility management technologies. In this paper we review the impact of some technologies, focussing the use of nutrient resources of different characteristics (qualities) in relation to improved crop yields, with an overall goal to enhance technology adoption. Thus, inorganic resources or fertilizers often give immediate crop responses, but their use or adoption is rather restricted to large-scale farmers who can afford to buy these materials. Organic resources, which include crop residues, water hyacinth and agroforestry shrubs and trees, are widely distributed, but they are generally of low quality, reflecting the need to apply large quantities to meet crop nutrient demands. Moreover, most organics will add N mainly to soils. On the other hand, phosphate rocks of varying reactivity are found widely in Africa and are refined elsewhere to supply soluble P sources. The recently developed soil fertility management options in East Africa have targeted the efficient use of N and P by crops and the integrated nutrient management approach. Some people have also felt that the repackaging of inputs in small, affordable quantities, such as the PREP-PAC described in this paper, may be an avenue to attract smallhold farmers to use nutrient inputs. Nonetheless, crop responses to nutrient inputs vary widely within and across agroecozones (AEZs), suggesting specificity in recommendations. We highlight this observation in a case study whereby eight soil fertility management options, developed independently, are being tested side-154 by-side at on-farm level. Farmers will be empoweredby-side at on-farm level. Farmers will be empowered to identify technologies from their own choices that are agronomically effective and economically friendly. This approach of technology testing and subsequent adoption is recommended for technology development in future
Bean Nodulation Patterns in Soils of Different Texture at Morogoro, Tanzania
(1998) Msumali, G.P.; Judith, A.K.
system in three soils of varying texture and % recovery of rhizobia I cells immediately after inoculation into such soils. Effects of inoculation methods (seed pelleting versus soil inoculation) on nodulation and plant growth were investigated in the three soils using a serologically- marked Rhizobium strain (ClAT 899) which was subsequently monitored in the nodules by the enzyme-linked immunosorbent assay (ELISA) technique. When the major soil chemical factors affecting nodulation were standardized, bean nodulation patterns continued to be closely related to soil texture, being higher in the sandy and loamy soils than in the fine-textured clay. Soil inoculation consistently gave better nodulation than seed pelleting.According to the ELISA procedure however, percent nodule occupancy by ClAT 899 showed patterns completely the opposite of the nodulation trends outlined above, being 100% in the clay but only 10% in the sandy soil. Thus, nodulation success by the inoculum was total in the clay but only dismal in the sandy soil. The unexpected discrepancy between inoculum success on the one hand and nodulation plus plant growth response on the other, is discussed.
Bean nodulation patterns in soils of different texture at Morogoro, Tanzania
(1998) Msumali, G.P.; Judith, A.K.
This study was designed to examine the, relationship between nodulation in a bean-Rhizobium system in three soils of varying texture and % recovery of rhizobia I cells immediately after inoculation into such soils. Effects of inoculation methods (seed pelleting versus soil inoculation) on nodulation and plant growth were investigated in the three soils using a serologically- marked Rhizobium strain (ClAT 899) which was subsequently monitored in the nodules by the enzyme-linked immunosorbent assay (ELISA) technique. When the major soil chemical factors affecting nodulation were standardized, bean nodulation patterns continued to be closely related to soil texture, being higher in the sandy and loamy soils than in the fine-textured clay. Soil inoculation consistently gave better nodulation than seed pelleting.According to the ELISA procedure however, percent nodule occupancy by ClAT 899 showed patterns completely the opposite of the nodulation trends outlined above, being 100% in the clay but only 10% in the sandy soil. Thus, nodulation success by the inoculum was total in the clay but only dismal in the sandy soil. The unexpected discrepancy between inoculum success on the one hand and nodulation plus plant growth response on the other, is discussed.
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.
Bringing evidence to bear for negotiating tradeoffs in sustainable agricultural intensification using a structured stakeholder engagement process
(Taylor & Francis, 2021) Winowiecki, Leigh Ann; Bourne, Mieke; Magaju, Christine; Neely, Constance; Massawe, Boniface; Masikati, Patricia; Vågen, Tor-Gunnar; Musili, Faith; Nabi, Muhammad; Nguyo, Anthony; Seid, Hadia; Hadgu, Kiros; Shoo, Aikande; Tembo, Howard; Chipatela, Floyd; Chesterman, Sabrina; Hughes, Karl; Temu, Emmanuel; Kimaro, Anthony Anderson; Sinclair, Fergus
Sustainable agricultural intensification (SAI) has the potential to increase food security without detrimental effects on ecosystem services. However, adoption of SAI practices across sub-Saharan Africa has not reached transformational numbers to date. It is often hampered by lack of context-specific practices, sub-optimal understanding of tradeoffs and synergies among stakeholders, and lack of approaches that bring diverse evidence sources together with stakeholders to collectively tackle complex problems. In this study, we asked three interconnected questions: (i) What is the accessibility and use of evidence for SAI decision making; (ii) What tools could enhance access and interaction with evidence for tradeoff analysis; and (iii) Which stakeholders must be included? This study employed a range of research and engagement methods including surveys, stakeholder analysis, participatory trade-off assessments and co-design of decision dashboards to better support evidence-based decision making in Zambia, Tanzania and Ethiopia. At the inception, SAI evidence was accessible and used by less than half of the decision makers across the three countries and online dashboards hold promise to enhance access. Many of the stakeholders working on SAI were not collaborating and tradeoff analysis was an under-utilized tool. Structured engagement across multiple stakeholder groups with evidence is critical.
Bringing evidence to bear on negotiating ecosystem service and livelihood trade-offs in sustainable agricultural intensification in Tanzania, Ethiopia and Zambia as part of the SAIRLA program
(Sokoine University of Agriculture, 2017-05) Massawe, B.; Johaness, N.; Winowiecki, L. A.; Neely, C.
The Sustainable Intensification of Agricultural Research and Learning in Africa (SAIRLA) Programme is a UK Department for International Development-funded initiative that seeks to address one of the most intractable problems facing small-holder farmers in Africa - how to engage in the market economy and to deliver sustainable intensification of agriculture, that is, which avoids negative impacts on the environment. SAIRLA will generate new evidence to help women and poor African smallholder farmers develop environmentally and financially sustainable enterprises and boost productivity. The research will focus non-exclusively on 6 countries (Burkina Faso, Ethiopia, Ghana, Malawi, Tanzania and Zambia), thus complementing other research efforts in these regions.