Soil Science Collection

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Soil erosion by water causes and cures with special reference to Mazimbu ANC-farm, Morogoro Tanzania
(Sokoine University of Agriculture, 1988) Kosaka, Sukenobu; Hauken, Marit
Literature concerning general theory about soil erosion by water, and soil conservation is studied. Emphasis is laid on literature concerning tropical climates and mechanized farming. Data of importance for soil erosion are collected for the Mazimbu ANC - farm in Tanzania. The collected data are used to assess present soil erosion at the farm, and to prepare a soil conservation plan for the farm. The main forms of soil erosion are splashing erosion, interrill erosion, sheet erosion, rill erosion and gully erosion. Soil erosion is affected by the erosive forces of the rain (ero-sivity), the vulnerability of the soil to be eroded (erodibility) and topographic factors such as slope steepness, slope length and slope shape. Live plants or plant residues on the soil surface are very effective in reducing erosion. erosion, Soil erosion assessment is a study of soil erosion state, erosion rate or erosion risk in an area. The assessment of erosion is important in land use planning and soil conservation work. Soil erosion models are valuable tools in the study of erosion. The Universal Soil Loss Equation (USLE) is an empirical model derived in USA. USLE predicts soil loss caused by rill and interrail and the equation can be used for the determination of conservation practices. There are several objections to transferring USLE to tropical climates. Another empirical model, Soil Loss Estimation Model for Southern Africa (SLEMSA) has been developed in Zimbabwe. Less input data is needed for SLEMSA thar for USLE. SLEMSA estimates soil loss by interrail erosion. Soil erosion can be controlled with soil and crop management and/or mechanical practices. The main objectives of soil and crop management in erosion control are to provide a soil surface that is resistant to erosion and to provide a protective cover of live plants or plant residues (mulch) on the soil surface. The main crop management factors in erosion control are crop rotations, the use of cover crops, multiple cropping, mulching, and strip cropping. It is also important to provide suitable nutrient conditions and growth conditions for the crops. Soil management in erosion control is mainly connected to tillage. Conservation tillage is tillage systems which reduce soil loss since crop residues are left on the soil surface and/or the surface is left rough, porous, cloddy or ridged. Several conservation tillage systems are described under the headings stubble mulch tillage, reduced tillage and no tillage.
Establishment of criteria for classification and mapping of soil erosion at farm scale level: a case study of Sokoine University of Agriculture farm, Morogoro, Tanzania
(Sokoine University of Agriculture, 2000) Kapele, William
The depth of the topsoil and estimated soil loss were used to assess the extent of past erosion and susceptibility to soil erosion of the Typic Rhodustalf and Typic Ustorthent, in the central part of the Sokoine University of Agriculture farm. The topsoil depth ranges: <15cm, 16 - 20cm and >20cm were used to categorise soils as highly eroded, moderately eroded and least eroded. Parameters of the Universal Soil Loss Equation: rainfall erosivity, soil erodibility, crop cover and management, and topographic factors were used to assess the susceptibility of soils studied to erosion. The following soil erosion susceptibility ranges: < 4Mg/ha/year, 4 - 8Mg/ha/year and >8Mg/ha/year were studied and used to represent highly eroded, moderately eroded and least eroded soils. For both criteria, areas with similar erosion classes were delineated, and both soil erosion susceptibility and soil erosion severity maps were drawn at scale 1: 5 000. The impact of soil erosion on maize yield was assessed using the two criteria. Generally there was a decline in maize yield as a result of increase in erosion. For the same erosion category, the Typic Rhodustalf had a higher yield than the Typic Ustorthent. The impact of estimated soil erosion susceptibility on maize yield was more consistent than that of topsoil depth. There existed a high correlation between estimated soil erosion susceptibility and maize grain yield (r2 = 0.60) and biomass (r2 = 0.49). In case of the topsoil depth criterion, the relationship was lower with r2 = 0.20 for grain yield and r2 = 0.26 for There existed a high correlation between estimated soil erosion susceptibility and maize grain yield (r2 = 0.60) and biomass (r2 = 0.49). In case of the topsoil depth criterion, the relationship was lower with r2 = 0.20 for grain yield and r2 = 0.26 for biomass. However, in the Typic Rhodustalf the correlation was high, grain yield (r2 = 0.70) and biomass (r2 = 0.46), while in the Typic Ustorthent the relationship was extremely low; grain yield (r2 = 0.09) and biomass (r2 = 0.24). Soil erosion susceptibility was therefore found to be a better criterion for assessing soil erosion than topsoil depth. However, multiple regression analysis of maize yield and other soil parameters produced high correlation, implying that the use of the topsoil depth can be improved by including some other soil parameters like bulk density and organic carbon for estimating the extent of past erosion.
Comparative evaluation of different techniques for soil erosion assessment in field plots
(Sokoine University of Agriculture, 1996) Mtakwa, Peter W.
Four techniques for assessing soil erosion were comparatively evaluated in field plots in bare - fallow as well as in plots under a maize - cowpea sequence for two consecutive seasons in 1935 at IITA, Ibadan, Nigeria. The techniques assessed were: Tracer, (Aluminium Paint), Hails (16 and 25 nails per plot), Rill and Universal soil, loss equation (USLE) technique. Soil loss determined by these techniques was compared to that measured by the conventional runoff plot technique. Soil loss measured by the conventional runoff plot technique was used for determining the influence of the various techniques on the magnitude of soil erosion. The Tracei technique war discontinued before the end of the study because it was difficult to accurately monitor the movement of the sprayed paint particles. The techniques employed in assessing soil erosion had no significant influence (5£ level) on the magnitude of soil loss and did not interfere with erosional processes. There was significantly more soil loss (ijo level) in bare fallow than in plots under a crop. from bare - fallow plots was 153.3 Llgha In the first season, soil loss —1 i -1 compared to only 40.2 ligha in plots under maize. lost 87o5 Kg soil ha _1 In the second season, bare - fallow plots -1 compared to a coil loss of 39.4 Kgha from plots tinder cowpea. liaise and cov/pea reduced the amount of soil loss by 5.8 and 2.2 times, respectively. There was more deterioration of soil physical conditions in bare - fallow than in plots under a maize - cowpea sequence. Det.veen the beginning of the first and the end of the second season there was a significant (1/j level) increase in dry bulk density in bare - fallow plots whereas the increase was nonsignificant (5/> level) in plots cropped to a maize - cowpea sequence. During the same period, cumulative infiltration and equilibrium infiltration rate fell by 41 and 37T-»j respectively, in bare - fallow plots compared to an increase (improvement) of about 26 and 37^ (cumulative infiltration and equilibrium infiltration rate, respectively) in plots under a maize cowpea sequence. There was no significant difference (5/j level) between soil loss determined by the 16 nails or 25 nails and conventional runoff plot technique. Also, soil loss determined by 16 nails did not differ significantly (5/J level) from that determined by the 25 nails technique. Soil loss determined by rill technique on six plots (3 bare fallow and 3 plots with, naize) at the end of the first season was significantly (5z-> level) lower than that measured by the conventional runoff plot technique. -1 and 121.9 Llgha for 11, Rill - estimated soil loss was 143.2. 103.8 a 11 and 8,'j slope, respectively,. -1 compare! To 201.5, 162.0 and 166.4 I.’gha measured by the conventional runoff plot technique. Soil erosion measured by the rill technique on three bare - fallow plots in 10 different dates was also significantly (ifj level) lower than that determined by the conventional runoff plot Technique. In the first season, the USL3 significantly (ijb level) underestimated soil loss. Soil loss estimated by the Ui-LE in the first season respectively for 11, 85.9 I-lgha"1 11 and Sf' slope was 128.8,-_ -1144.3 ana compared to 167.6, 156.1 and 136.3 i-gha' measured by the conventional runoff plot technique. in the second season, however, there were no differences in erosion rates determined by the two techniques. Cowpea grain yield was significantly (5f> level) and negatively correlated to soil loss (r = 0.74).
Studies on phosphate sorption in Tanzania haplustox and vitrandept soils
(Sokoine University of Agriculture, 1979) Gama, Benjamin Michael
Two virgin soils, a Haplustox with appreciable amounts of kaolinite, amorphous ferrialunino silicate (ATAS), and oxides and liydrous oxides of iron, and a Vitrandept dominant in ADAS with very little crystalline minerals, were chosen for this project. Phosphate sorption in these soils were investigated with respect to length of equilibration, initial solution concentration and pH, organic natter content, and amount and nature of extractants. It was also attempted to assess the equilibrium-? required for near maximum growth of maize (Zea nays L. vor. Ilonga composite) end bean (Phaseplus vulgaris L, var Canadian wonder) in the greenhouse. With respect to the length of equili' ration, rapid P sorption was observed initially in both the soils but near equilibrium condition was obtained only after 24 hours. The magnitude of sorbed-? increased with increasing initial P concentration in the equilibrating solution. The initial solution pH had no effect on P sorption. Destruction of organic natter led to over threefold increase in P sorption in both the soils. Studios in into greenhouse showed that dry matter yield} percent P in plant tissues and total P uptake for both the crops grown on either soil increased with increasing equilibrium -P up to certain concentration beyond which these parameters tended to reach a plateau. On the Haplustox soil. 95 percent of the maximum rinse yield was obtained are on adjusted P concentration of 9.7 P/ml while 2.6 jpg P/ml was odocuate on the Vitrondept soil, 95 percent of the maximum maize yield was obtained at 9.5 and 5 kg, 1/ml adjusted P concentration in the Vitrandept haplustox soils, respectively. From economic considerations, however an adjusted P concentration lower than that required for 95 percent of the maximum yield is suggested
Characterization of Sukumawera and Kisarawe bat guano from Tanzania as soil amendment and source of plant nutrients
(Sokoine University of Agriculture, 2016) Twisege, Andrew
Guanos are excrements of birds and/or bats enriched with varied nutrients. In Tanzania. guanos are found in a number of places but are not fully utilized due to lack of information on their agronomic potential. Therefore, a study was conducted on Sukumawera and Kisarawe bat guano to assess their agronomic potential as soil amendment and source of plant nutrients for maize production. Elemental composition of the studied guanos were analysed al the Geological Survey Laboratories in Dodoma using inductively' coupled plasma - optical emission spectrometer (ICP-OES). Their physico chemical properties were determined at Sokoine University of Agriculture (SUA) Soil Science Laboratories. Pot experiments were carried out at SUA to assess maize response to soil applied with varying amounts of bat guano. Number of leaves, plant height. biomass weight, nutrient concentrations in soils and plants were among the variables assessed. The ICP-OES results indicated that Sukumawera had high level of P ranging from 20 - 41%. while in Kisarawe bat guano its P value was 7 - 15%. Similarly. Sukumawera bat guano had higher level of S (19 - 39%) as compared to that of Kisarawe (6 - 13%). Laboratory analysis found that both guanos are slightly acidic to strongly acidic (pH 4.2 - 6.7). There was significant (p < 0.05) increase in soil nutrient concentrations and nutrients uptake by maize as guano rate increased. Howexer. the best plant performance was observed at a ratio of 20 : 0.5 for Sukumawera and 20 : I for Kisarawe guano. Kisarawe bat guano was superior to Sukumawera in plant performance. The study revealed that high rates of guano application (> 20 : 1) caused poor maize response. It was concluded that both Sukamawera and Kisarawe bat guano are suitable for alkaline soils amendment and source of plant nutrients when applied in small amounts (< 20 : I) for good plant performance. It is recommended that field trials should be carried out to assess the actual maize plant response in the natural environment.
Genotypic variation in phosphorus requirement and utilization in nodulated common beans (phaseolus vulgaris l.)
(Sokoine University of Agriculture, 1992) Ole-Meiludie, Dorothy John Simon
A study to investigate the genotypic variations in phosphorus requirement and utilization by four common bean genotypes AA/2/5/6xK-2; 86EP 5091-B-2; EP 3-2 and Selian wonder, referred to as C2' C4' C5 and C8 respectively, inoculated with a locally produced Rhizobium strain, PV1, was carried out at the Sokoine University of Agriculture, Morogoro, Tanzania in a glasshouse pot experiment. The soil used as the growth medium was an Oxic Haplustult with low levels of total nitrogen and Bray-1 phosphorus with a slight acid reaction. phosphorus applied were 0, The 5, 10, 20, 40, 160mgP/kg soil as kh,poa Z 4 extractable levels of 80, 120 and and these rates were each replicated six times for each common bean genotype. The increases in the number of nodules, (hence nodulation), nodule weights, shoot dry weights, root dry weights, pod production, seed production, percent N in the shoots and percent P in the shoots with increasing rates of applied phosphorus were significant and these plant parameters were positively and significantly correlated to one another, suggesting the vital role of phosphorus in symbiotic nitrogen fixation. The variations in phosphorus requirement and utilization based on the above plant parameters were attributed to the inherent genetic characteristics of the four common bean genotypes. The genotypes most tolerant to low levels of Bray-1 extractable phosphorus fixed more nitrogen symbiotically and accumulated more dry matter. The genotypes' tolerance phosphorus followed to low levels of the order different phosphorus rates C5 > C4 > for optimum symbiotic nitrogen fixation for each C2 extractable > C8‘yields individual. The and common bean genotype should be established in a similar investigation under field conditions. The ability of the genotypes to form nodules hence fix inoculated with the Rhizobium nitrogen, strain PV1 indicate when the ability of the Rhizobium strain PV1 to tolerate low levels of Bray-1 extractable phosphorus. Based on the results and C4 inoculated obtained in this study, the genotypes C5 with Rhizobium strain PV1 can be grown in soils deficient in available phosphorus without any effect on reducing seed yield.
Genotypic variation in phosphorus requirement and utilization in nodulated common beans (phaseolus vulgaris l.)
(Sokoine University of Agriculture, 1992) Ole-Meiludie, Dorothy John Simon
A study to investigate the genotypic variations in phosphorus requirement and utilization by four common bean genotypes AA/2/5/6xK-2; 86EP 5091-B-2; EP 3-2 and Selian wonder, referred to as C2' C4' C5 and C8 respectively, inoculated with a locally produced Rhizobium strain, PV1, was carried out at the Sokoine University of Agriculture, Morogoro, Tanzania in a glasshouse pot experiment. The soil used as the growth medium was an Oxic Haplustult with low levels of total nitrogen and Bray-1 phosphorus with a slight acid reaction. phosphorus applied were 0, The 5, 10, 20, 40, 160mgP/kg soil as kh,poa Z 4 extractable levels of 80, 120 and and these rates were each replicated six times for each common bean genotype. The increases in the number of nodules, (hence nodulation), nodule weights, shoot dry weights, root dry weights, pod production, seed production, percent N in the shoots and percent P in the shoots with increasing rates of applied phosphorus were significant and these plant parameters were positively and significantly correlated to one another, suggesting the vital role of phosphorus in symbiotic nitrogen fixation. The variations in phosphorus requirement and utilization based on the above plant parameters were attributed to the inherent genetic characteristics of the four common bean genotypes. The genotypes most tolerant to low levels of Bray-1 extractable phosphorus fixed more nitrogen symbiotically and accumulated more dry matter. The genotypes' tolerance phosphorus followed to low levels of the order different phosphorus rates C5 > C4 > for optimum symbiotic nitrogen fixation for each C2 extractable > C8‘yields individual. The and common bean genotype should be established in a similar investigation under field conditions. The ability of the genotypes to form nodules hence fix inoculated with the Rhizobium nitrogen, strain PV1 indicate when the ability of the Rhizobium strain PV1 to tolerate low levels of Bray-1 extractable phosphorus. Based on the results and C4 inoculated obtained in this study, the genotypes C5 with Rhizobium strain PV1 can be grown in soils deficient in available phosphorus without any effect on reducing seed yield.
Effects of nitrogen sources and rates on soil tissue nutrient concentration and properties, yield of cotton (gossypium hirsutum l.) In soils of the university farm, Morogoro
(Sokoine University of Agriculture, 1990) Mwaganicha, Thobias Kinyamagoha
Pot and field experiments were carried out to investigate the effects of different rates and sources of N in soils with different initial pH on soil chemical properties, tissue nutrient concentration, growth and yield of cotton at the University Farm, Morogoro. Nitrogen rates applied were 0,150 kg N/ha and the N sources were SA, 50, 100 and urea and CAN. The soils used had initial pH values of 4.8, 6. 1 and 6.9 and were designated as strongly acid soil (SAS), moderately acid soil (MAS) and almost neutral soil (ANS), respectively. The experimental design was a split-plot with N rates as N sources as main plot and N source plots. Soil chemical properties assessed were pH, exchange able acidity, Al, bases and Mn. Concentration of N, P, Mn were determined in Ca and leaf tissues at flowering in the pot study and at flowering and boll stages of cotton development in the field experiment. Shoot dry weight, plant heights, number of fruiting branches, number of flowers, number of bolls, number of early maturing bolls, as well as seedcotton yield and one thousand seeds weight were also determined Nitrogen application above the control significantly increased exchangeable acidity and aluminium in the SAS, the effects being mainly due to different rates of SA. Other soil chemical properties in SAS and all measured properties in MAS and ANS were not significantly affected by the rates and sources of N. Nitrogen application significantly increased N concentration in leaf tissues except that of leaf blades at flowering in SAS and in both petioles and leaf blades at boll development stage in ANS. The N concentration at flowering associated with maximum seedcotton yield was 2.0% for petiole N and 4.4% for leaf blades N. While P and Ca concentrations in leaf tissues at flowering were significantly increased due to different rates of CAN, Ca concentration was significantly decreased at 150 kg N/ha applied as SA and urea in the SAS. in leaf tissues at Manganese concentration flowering was significantly increased due to various rates of SA in the SAS, and in leaf blades at flowering and boll stages of cotton development in the ANS. Shoot dry weight, branches, plant heights, number of fruiting number of flowers and number of bolls were significantly increased by N application. Were early maturing bolls not significantly affected by N application. Nitrogen sources did not significantly affect the growth and reproductive characters of cotton, except shoot dry weight in the field experiment at flowering which was significantly increased by SA. Seedcotton yield and one thousand seeds weight were significantly increased by N application, with maximum responses being at 100 kg N/ha. Nitrogen sources had no significant effects on the yield components of cotton in the ANS. Nitrogen concentration in leaf tissues was significantly correlated with shoot dry weight and yield of seedcotton. It was therefore concluded that (i) consideration of N sources was necessary in the SAS but was appearing irrelevant in the MAS and ANS, (ii) the agronomic optimum N rate was close to 100 kg/ha for these soils and (iii) concentration of N in petioles and leaf blades at flowering could be used to assess the N I status of cotton plants with values of 2.0% and 4.1l% respectively, being tentatively suggested as optimum.
Assessment of suitability of the soils of madura research institute, Arusha, Tanzania, for the production of soybeans and mungbeans
(Sokoine University of Agriculture, 2001) Mlahagwa, Moses Raphael
A field study was conducted to assess the suitability of the soils of Madiira Research Institute farm for the introduction of growing and production of vegetable soybeans and mungbeans in Tanzania. The specific intention was to assess the fertility status of the soils, determine the plant uptake of the essential nutrient elements from the soils, and try to suggest measures and soil fertility management strategies for the sustainable and optimal production of vegetable soybean and mungbean production. Composite soil samples for the determination of the physical and chemical properties were sampled from two sites selected on the farm. About 400 m2 of land for each site was plowed and then harrowed and each site was divided into three 8 m x 6 m plots/blocks for four soybeans and for five mungbeans, grown at a spacing of 30 cm x 10 cm and replicated three times respectively. Just before flowering nine plants of each line and from each block were harvested for dry matter yield determinations and total plant nutrient analysis. The other plants were left on the field to grow to maturity for grain yield determinations. The soils were found to be medium acidic, with medium CEC, OC, exchangeable Ca, and Mg, low levels of total N, and high levels of exchangeable K and Bray-1 P. The DTPA extractable Fe and Cu were above the critical limit, while Zn and Mn were medium. The plant analysis for soybeans showed that P and Zn correlated positively with the dry matter yields while total N, Ca, Mg, K, Fe, Cu and Mn correlated negatively with the same. Nitrogen, Mg, K, Fe, Cu and Mn correlated positively with grain yields while Ca, Zn and P correlated negatively with the same. The plant analysis for mungbeans showed that N, Mg, K, Zn and Cu correlated positively with dry matter yields while P, Ca, Fe and Mn correlated negatively with the same. Nitrogen, Mg, K, Zn, Cu and Mn correlated positively with grain yields while Ca, Fe and P correlated negatively with the same. The soybean performances based on fresh grain yields were in the following order: GC 84051-32-1 AGS 338 > AGS 329 > AGS 292 corresponding to 14730.0, 8861.6, 6447.0, and 6364.3 kg/ha respectively, while mungbean performances were: VC 6173(b-10) VC 6148(50-12) > VC 6372(45-8) > VC 6379(232-1) > KANTI corresponding to 11178.0, 10549.3, 9167.6, 8547.0 and 6553.3 kg/ha respectively. The soils analytical data indicate that the soils are of medium fertility status, that is medium levels of CEC (16.2-16.8 cmol (+)/kg soil), OC (1.3-1.5%), Ca (8.0-8.1 cmol (+)/kg soil), Mg (2.7-3.0 cmol (+)/kg soil) and low levels of total N (0.190.22%), hence can support the growth of soybeans and mungbeans in the short-term period. Recommendations are made to publicise the production of the best two high yielding soybean lines (i.e. GC 84051-32-1 and AGS 338) and mungbean lines (i.e. VC 6173(b-10) and VC 6148(50-12). Seed inoculation for effective Ni-fixation is recommended. On-site incorporation of the legume vegetable crop residues into the soils and further experiments and use of fertilizer rates are recommended for the sustainable soybean and mungbean production.
Effects of spraying coffee with copper fungicides on the copper status of soils of Moshi district, Tanzania
(Sokoine University of Agriculture, 1990) Mkindi, Gerard Isaac
A series of investigations assess the were conducted to effects of spraying coffee with copper (Cu) fungicides on the Cu status of some soils of Moshi district, Tanzania. The studies involved analysis of soil samples taken from coffee fields sprayed with Cu fungicides for durations of 10 years, 10 30 years, >30 years and from fields which have not been sprayed. Copper from the soils was extracted using 0.005M DTPA. Then three glasshouse experiments were set the effects of different Cu levels in soils pH on up to assess and soil the growth of beans and Cu concentration in shoots. In addition, coffee from selected coffee leaves were collected the fields and analysed for Cu content. The results indicated that DTPA extractable Cu in the topsoil (0-5cm) of 5.6 ppm in farms increased from an average that had never been sprayed with copper fungicides to more gave than 30 years. 186.2 ppm in farms sprayed for shorter durations of spraying intermediate values of extractable ctable Cu Cu. decreased sharply with depth. The extra Beans grown in soils ranging in DTPA Cu contents from 3.7 to 368 PPm had a shoot of 23.2 ppm and in any no of the treatments. average Cu content in the toxicity symptoms was observed. Application of 200pg Cu/kg soil increased the average Cu content of shoots to 25.6 ppm but again the plants were free from any Cu toxicity. Coffee leaves from sprayed fields contained higher levels of copper (up toGOppm) but were also free from Cu toxicity symptoms. 5.1 However, when pH was lowered to or less, copper concentration in bean shoots increased to 35 ppm or greater and caused copper toxicity to bean plants. It was concluded that spraying coffee with copper fungicides increased the amount of copper in the soil and that the largest increase occurred in the 0-5 cm layer of soil. Not the copper accumulated in the soil was toxic to either coffee or bean plants but could become toxic if the pH of the soils decreased below 5.2.
Measurement of soil water evaporation using microlysimeters of different sizes: effect of shade and soil texture
(Sokoine University of Agriculture, 1996) Maseko, Stephen Phuz’ukuvela
The effect of soil texture and shade on soil water evaporation using microlysimeters of different sizes was investigated. The rate of evaporation from the different sized microlysimeters was studied to see which evaporates the most. The days after irrigation were monitored to see if evaporation would increase or decrease. The effect of the depth of the microlysimeters was also studied to find out which depth evaporates more between the shallow depth microlysimeters (SDM) (10 cm), and the deeper depth microlysimeters (DDM) (20 cm). Two periods of the day, morning period (MP) and afternoon period (AP) were also studied to determine which one had more evaporation. The study, which was conducted from October to December 1994, was carried out in two sites with contrasting soils viz; (a) Ismani, in Iringa region selected for its clayey soils, and (b) Hombolo, in Dodoma region which had sandy soils. For the experiment, two plots were used, one shaded and the other unshaded. Shading was obtained by using a shade screen (a black net) which provided a shade of about 50 per cent. Sixty mm of irrigation water was applied on both plots at the same time. Results show that sandy soils evaporated significantly (P<0.05) more water, up to about 20 per cent, than clayey soils. Shading significantly (P<0.05) reduced evaporation by 5 to 10 per cent. The 10 cm diameter microlysimeters lost more water than the 5 cm diameter ones. This was prominent in clayey soils (P<0.05) than in the sandy soils, at the initiation of the experiment. However, towards the end of the study the difference was reduced. It was also observed that evaporation significantly decreased as the soil progressively dried after irrigation. The second day’s evaporation was reduced by almost 50 per cent. The rest of the days’ evaporation was steady at about 10 to 20 percent of the first day. There was no significant difference between the SDM and DDM. It seems depth (10-20 cm) does not significantly affect evaporation. The periods of the day showed some significant difference. In clayey soils significantly (P<0.05) more water was lost in the MP than in the AP. However, the reverse was true for the sandy soils.
Measurement of soil water evaporation using microlysimeters of different sizes: effect of shade and soil texture
(Sokoine University of Agriculture, 1996) Maseko, Stephen Phuz’ukuvela
The effect of soil texture and shade on soil water evaporation using microlysimeters of different sizes was investigated. The rate of evaporation from the different sized microlysimeters was studied to see which evaporates the most. The days after irrigation were monitored to see if evaporation would increase or decrease. The effect of the depth of the microlysimeters was also studied to find out which depth evaporates more between the shallow depth microlysimeters (SDM) (10 cm), and the deeper depth microlysimeters (DDM) (20 cm). Two periods of the day, morning period (MP) and afternoon period (AP) were also studied to determine which one had more evaporation. The study, which was conducted from October to December 1994, was carried out in two sites with contrasting soils viz; (a) Ismani, in Iringa region selected for its clayey soils, and (b) Hombolo, in Dodoma region which had sandy soils. For the experiment, two plots were used, one shaded and the other unshaded. Shading was obtained by using a shade screen (a black net) which provided a shade of about 50 per cent. Sixty mm of irrigation water was applied on both plots at the same time. Results show that sandy soils evaporated significantly (P<0.05) more water, up to about 20 per cent, than clayey soils. Shading significantly (P<0.05) reduced evaporation by 5 to 10 per cent. The 10 cm diameter microlysimeters lost more water than the 5 cm diameter ones. This was prominent in clayey soils (P<0.05) than in the sandy soils, at the initiation of the experiment. However, towards the end of the study the difference was reduced. It was also observed that evaporation significantly decreased as the soil progressively dried after irrigation. The second day’s evaporation was reduced by almost 50 per cent. The rest of the days’ evaporation was steady at about 10 to 20 percent of the first day. There was no significant difference between the SDM and DDM. It seems depth (10-20 cm) does not significantly affect evaporation. The periods of the day showed some significant difference. In clayey soils significantly (P<0.05) more water was lost in the MP than in the AP. However, the reverse was true for the sandy soils.
Assessment of uranium levels in selected soils and its uptake by rice, maize and millet in Bahi district, Tanzania
(Sokoine University of Agriculture, 2014) Makoti, Clavery Atiianas
This research aimed to determine levels of uranium (U) contamination in selected agricultural soils of Bahi District and its uptake by food crops in order to enhance public awareness and safety. The research involved determination of spatial distribution of U in agricultural soils, its uptake and translocation in plant/crop tissues. Soil, plant and water samples were collected randomly from farmers' fields and water sources, respectively. Laboratory sample analysis was done at the Government Chief Chemist Laboratory in Dar es Salaam and Soil Science Laboratory at the Sokoine University of Agriculture. Substantial differences of U concentrations in soils, plants and water were determined. The highest U level in soil profiles was 74.8 pg kg’1 at Mpamantwa and the lowest was18.3 pg kg’1 at Hindi. Along the studied transects, the highest U level was 743 pg kg’1 at Bahi and lowest was 13.6 pg kg’1 at Hindi. Uranium concentrations in maize and rice were below detectable limit (<10 pg L"1) except for finger millet where U accumulation levels ranged from 10.4 to 32.0 pg kg‘l. The concentration of U in water differed from village tovillage. The highest U level of 1233 pg L’1 was found in Hindi village at Hindi Playa Lake whereas in Bahi the highest U concentration was 62.9 pg L’1 found in one of the Bubu tributaries under the bridge. The concentrations of U in water in Hindi and Bahi villages were more than 30 pg L’1 the tolerable limit set by WHO for human and animal consumption. The levels of U in soils and crops were within the tolerable limit for agricultural use and the environment. Further studies should be carried out for other types of crops that are grown in the Bahi District villages to assess their safety for human consumption.
Response of maize to nitrogen, phosphorus and filtermud applied to a dystric nitosols
(Sokoine University of Agriculture, 2003) Luambano, Nessie
A glasshouse pot experiment to study the response of maize (Zea mays') to nitrogen, phosphorus and filtermud applied to a Dystric nitosols was carried out at the Sokoine University of Agriculture (SUA) Morogoro, Tanzania. The Dystric nitosols was collected from the central part of SUA farm while the filtermud was obtained from Mtibwa Sugar Factory, Turiani Morogoro, Tanzania. The Dystric nitosols was characterized by low total organic carbon, nitrogen, exchangeable Ca and Mg, CEC, plant available P and a very strongly acid reaction. The filtermud contained low amounts of the essential nutrients elements and had a very mild alkaline reaction. Fifty four, 12 kg soil sample portions of the Dystric nitosols were weighed into 10 litre capacity plastic buckets and thoroughly mixed with nitrogen as (NH^SCXi at the rates of 0, 50 and 100 kgNha'1, P as KH2PO4 at the rates of 0, 75 and 150 kg P ha’1 and filtermud at the rates of 0, 15 and 30 tonsfiltermudha’1 in a 3° factorial experiment in a completely randomized block design with two replicates. The soil-N-P-filtermud treatments were incubated at field capacity for 3 weeks after which five maize seeds were planted in each pot and allowed to grow for 6 weeks. The whole maize plants above the soil levels in the plastic buckets were harvested according to treatments at the end of the 6th week of growth and dried at 70 °C to constant weights for dry matter determination. The oven dried maize plants were chopped into small pieces and ground into fine powder for the determination of N, P and K contents. The application of N, P alone and in combination and N-P-filtermud combinations significantly increased the dry matter yields and percent N, P and K in the maize plants. The increases in the N, P and K contents in the maize plants were attributed to increased availability of N, P and K added to the soil as N and P fertilizers and the N, P and K released from the filtermud through decomposition and mineralization. Further, improvement of the physical, chemical and biological properties of the soil by the filtemud could have contributed to increased uptake of N, P and K. However, application of filtermud alone decreased the N, P and K contents of the maize plants and this was attributed to the immobilization of these nutrients in the soil. Filtermud could be used as an organic soil amendment when applied together with inorganic fertilizers for the enhancement and sustainability of soil fertility. Application of inorganic fertilizers and filtermud would improve soil productivity without detrimental effect to the environment.
Assessment of copper and zinc status of some soils of Iringa district
(Sokoine University of Agriculture, 1992) Mkangwa, Chaboba Zaid
The objectives of this study were to select suitable extractants for determining available copper and zinc in soils of Iringa district and to assess the fertility status of the two nutrients in the district. Two sets, each of ten soils for one element, were selected for glasshouse studies using maize as a test crop. The soils were treated with 0 and 5 kg ha' of either copper or zinc in their respective trials. Three extractants, viz: 0.1M EDTA-(NH.)jCO;, 0.005M DTPA and 0.1NHC1 were tested for their suitability to extract these elements. The concentrations of these elements in maize shoots were also determined. A total of 61 samples were collected from the district and analyzed for copper and zinc using the methods found to be suitable. Copper and zinc application slightly increased dry matter in four and eight soils, respectively, out of the ten soils tested. However, the increase was not statistically significant. The 0.1N HC1 extractant was superior to the other two in extracting zinc but none of the methods was suitable for copper. The tentative critical concentration for zinc was found to be 0.28ppm. Application of either of these elements in the soils, significantly increased their concentration in the plants. The tentative critical 6.30ppm. copper concentration in maize shoots was For zinc, the critical concentration in shoots was not determined because all the values obtained were above critical concentration extractant, range reported elsewhere. zinc concentration Using the 0.1N HC1 in the soil ranged from 0.14 to 27.30 ppm. For zinc, two fertility classes: medium and high were obtained. The proportions of soils which fell in the medium and high zinc fertility classes were 8.20 and 51.80%, respectively.
Evaluation of minjingu phosphate rock as a source of phosphorus for grapevine production in Dodoma district Tanzania
(Sokoine University of Agriculture, 1995) Budotela, George Masanja Raphael
Experiments were conducted to assess the P status of selected soils of Dodoma district, Tanzania and the response of grapevine to P application. The experimental sites were Msalato A, Msalato-Manispaa and Veyula Makutupora. The studies included (i) the initial fertility characterization of the incubation study and (iii) experimental soils (ii) an a field trial which compared MPR and TSP as sources of P. Results from the characterization study showed that fertility status decreased with increasing distance from the tree trunk congruent to the location of the fertilizer band. In the incubation experiment, solubility of MPR was found to increase steadily with time until equilibrium was reached at about 45 days. At this time 52% of the applied MPR, equivalent to 260 mg P/kg had dissolved. Soil samples incubated with TSP at this time released 64% of soluble P. Calcium and Phosphorus sinks were demonstrated as important parameters which influenced P dissolution in the test soils. In the field trial, both TSP and MPR application increased grape yield significantly over the control with TSP giving higher yield than MPR. The relative agronomic effectiveness (RAE) value for MPR averaged 67%, suggesting that TSP had a higher fertilizer value. The study further demonstrated that P rates above 168 kg P/ha decreased grape yields at Veyula-Makutupora site while at Msalato A and Msalato-Manispaa sites yields continued to increase. From these findings, it was concluded that: in addition to N, P application was needed in order to optimize grape yield in Dodoma district and a tentative rate of 168 kg P/ha is recommended. Minjingu PR was found to be a promising substitute for TSP but assessment of residual effects should be made before a definite recommendation can be made. Further research should be conducted to increase P use efficiency.
Effect of gliricidia sepium green manure placement on solubility of minjingu rock phosphate, growth and yield of maize at SUA farm, Morogoro, Tanzania
(Sokoine University of Agriculture, 2000) Kimaro, Anthony Anderson
This study was carried out at Sokoine University of Agriculture (SUA) Farm, Morogoro, Tanzania to assess the effect of Gliricidia sepiutn green manure (GM) placement method on solubility of Minjingu rock phosphate (MRP), growth and yield of maize. The study involved pot and field factorial experiments with treatments arranged in a complete randomized block design in three replications. For the pot experiment, the experimental factors were G. septum. GM placement method (5 t ha’1) at three levels (i.e. No GM, Incorporation and Mulching) and P- fertilizer application rates at seven levels (i.e. 0, 12.5, 25, 50, 100, 150 mg P kg soil’1 as MRP and 50 mg P as TSP). Air dried soil (2 kg) was filled in each of the 63 pots representing the 21 treatment combinations. The various treatments were then incubated at 70% field capacity (FC) at ambient temperature for three months. Within this period soil sub samples were collected at two weeks intervals for available phosphorus (AVP) deter mination in the laboratory. For the field experiment, the experimental factors remained the same as for the pot experiment except that the P-fertilizer application rates were 0, 10, 20, 40, 80 kg P ha’1 as MRP and 30 kg P ha’1 as TSP. Soil samples were collected at two weeks intervals for the determination of AVP in the laboratory. Additionally, maize height (m) at tasseling stage was recorded and maize samples were collected for the determination of P and N in the leaf, grain and stover. Grain and stover yields were also determined at maturity. The results indicated that GM placement method significantly improved AVP in both pot and field experiments, with the highest AVP obtained by the incorporation treatment. In most of the sampling dates AVP values for incorporation and mulching treatments were not significantly different in both the pot and field experiments. The AVP increased with increase in MRP application rates for both experiments and for all sampling dates. Except for stover N, GM placement method significantly increased concentration and content of P and N in maize leaf. For the incorporation treatment, the values were leaf concentra- tion (0.2005% P; 2.298% N) and leaf content (5.835mg P; 66.19 mg N). The corresponding values for the mulching treatment were leaf concentration (0.1908% P; 2.252% N) and leaf content (5.426 mg P; 63.43 mg N). Similarly, P and N uptake were significantly increased by GM placement method. The uptake values for incorporation treatment were as follows: grain (6.22 kg ha"1 P;37.82 kg ha"1 N), stover (2.18 kg ha"1 P; 10.98kg ha"1). Whereas corresponding values for the mulching treatment were grain (5.40 kg ha"1 P; 33.77 kg ha"1 N), and stover (1.76 kg ha"1 P; 9.59kg ha"1). Total P and N and maize height as affected by GM placement method followed a pattern similar to that of P and N for grain and stover. Maize yield was (2.07 kg ha"1 grain; 2.57 kg ha"1 stover) for control, (2.60 kg ha"1 grain; 3.33 kg ha'1 stover) for incorporation and (2.34 kg ha"1 grain; 2.98 kg ha"1 stover) for mulching. P and N uptake by maize significantly increased with increase in MRP application rate. However, at higher rates (i.e. 40, 80 kg P ha"1 as MRP), the increase of maize leaf P and P uptake was not significant. Generally, most of the parameters studied showed a linear and quadratic relationship with MRP application rates. Furthermore, the interactions between GM placement method and MRP application rates for most of the parameters studied were not significant. Based on the results of this study, it was concluded that incorporation and mulching of GM has the potential to improve solubility as well as growth and yield of maize. However, adoption of the practice may be limited because of the labour required in cutting, transporting and incorporating the GM into the soil. Getting a source that will provide sufficient amount of GM to cater for the needs of most of small holder farmers at the appropriate time may also be a problem. Furthermore, GM in this study was used as a source of N for maize and this is merely transferring nutrients within the farm and not actually redressing the nutrient depletion in the soil, therefore it may not be sustainable in the long run.
Influence of legume biomass on soil fertility status and maize performance in striga infested soils of Iringa, Tanzania
(Sokoine University of Agriculture, 2013) Hepelwa, Rebeca
The effect of incorporation of legume biomass residues on Striga infested soils was evaluated at Mangalali and Kiwere villages in Iringa district, Tanzania. Six legumes: [cow pea (Vigna unguiculata). green gram (Vigna radiatci), mucuna (Mucuna puriens). jack beans (Canavalia ensiformis), sunhemp (Crotaliria ochroleuca) and chick pea (Cicer arielinum)] plus two controls (no fertilizer added and one level of fertilizer 80 kg N ha-1 as urea) as nitrogen source were evaluated in randomized complete block design experiment. The legumes and their biomass quantities were incorporated into the soil four weeks prior to planting maize during 2011/12 growing season in the field. Significant differences (P<0.05) were recorded for soil chemical properties. Soil pH increased from (6.33 to 6.39) and (4.88 to 5.31) at Mangalali and Kiwere villages respectively. The highest organic carbon increase was recorded in plots incorporated with cowpea and mucuna with increases of 14% and 5% compared to chickpea (1%) at Mangalali village. At Kiwere village the highest organic carbon increase were recorded in plots incorporated with sun hemp (38%) and cow'pea (36%) compared to chickpea (1%). The highest N increase was observed in sun hemp (101.8%) followed by cowpea with an increase of (90.2%) compared to chickpea (12%) at Mangalali village, while at Kiwere village the highest N increases were recorded in sun hemp and cow-pea with increases of 553.84% and 541.67%, respectively compared to green gram (169.23%). Mucuna, sun hemp and cowpea also improved soil pH, organic carbon, total nitrogen and available P. Hence there were significant differences (P sun hemp (3.5 t ha'1) > mucuna (3.4 t ha'1) > green gram (2.3 t ha'1) > canavalia (2.1 t ha'1) > chick pea and control (1.6 t ha'1). Among legumes, cowpea incorporation was observed to produce higher yield compared to the other studied legumes. The incorporation of cowpea, mucuna and sunhemp legume residues are recommended to be used by poor resource farmers to improve soil fertility, reduce Striga infestation and increase maize yield in Striga infested areas with low soil fertility.
The effect of soil type, manure application rate and placement method on the decomposition of, and nitrogen release from, senna siamea green manure
(Sokoine University of Agriculture, 1996) Haru, Ruth Watiri
The decomposition and nitrogen release of Senna siamea green manure was studied under glasshouse and field conditions. The effects of two soil types, two manure application rates and two methods of manure placement on the decomposition rate were monitored by use of three parameters, namely residual dry matter, organic carbon and total nitrogen. These parameters were measured at the 1st, 3 rd 6ch 9 th and 12th week of manure incubation in the glasshouse while in the field, measurements were made at the 3rd 6 th and 9ch week. The glasshouse study revealed that there was no significant (p=0.05) difference between the decomposition rates, at 10 cm depth, in a Rhodustult (soil 1) and Dystropept (soil 2) as indicated by the three parameters. The manure decomposed faster at a lower application rate (60 kg manure-N/ha) than at a higher rate (150 kg manure N/ha) . Under field conditions, buried manure decomposed faster in soil 2 than in soil 1 while for the surface placed manure the opposite was observed. In soil 1, where termite activity was appreciable, the surface-applied manure decomposed faster than the buried material while in soil 2 manure. the decomposition rate was faster for the buried. The trends of manure decomposition were similar under the two incubation conditions but the decomposition rate after the third week was significantly higher in the field than in the glasshouse. The results of the present study indicated that in the glasshouse, the decomposition rate of green manure was not affected by the soil types used. But the decomposition varied with soil type, manure application rate as well as the mode of placement in the field. Therefore these factors should be considered when conclusions are to be made with respect to nutrient release from this manure.
Assessment of zinc and copper status in soils of the central part of Sokoine University of Agriculture farm, Morogoro, Tanzania
(Sokoine University of Agriculture, 1999) Gideon, Ngerageza Faraja
A study was conducted to assess the zinc and copper status in the soils of the central part of Sokoine University of Agriculture (SUA) farm. Twelve soil samples were collected from selected areas in the farm. Zinc and copper in these soils was extracted with four extractants namely 0.005M DTPA-TEA (pH 7.3), 0.005 DTPA-AB (pH 7.3), double acid (0.05M HC1 + 0.0125M H2SO4) . 0.1M HC1 and Two soils (Oxic Haplustult and Typic Rhodustult) out of the twelve soils were used for glasshouse experiment determine to response of beans (Phaseolus vulgaris) to zinc and copper zinc and application. The soils were each treated with copper at the rates of 0, 2.5, 5 and 10 Kg/ha. the Zinc application generally increased the dry matter yield plants in dry matter yield) was both soils. The increases of bean significant when compared to the dry matter yields of the controls. Copper application increased dry matter yield in the Oxic Haplustult where there were positive response to copper application. However negative response (decrease in observed in the Typic Rhodustult. Zinc and copper tissue- concentrations in bean shoots and were their uptake were significantly increased in both soils by the application of zinc and copper. However, the tissue zinc and copper concentrations observed were rather high and above the critical concentrations reported in the literature. Of the four extractants tested, 0.005M DTPA TEA was found most suitable for assessing the available zinc in the soils since it gave significant correlations with plant parameters (dry matter yield, tissue zinc concentrations and zinc plant uptake). The 0. IM HC1 was the second in suitability. However, none of the methods was found to be suitable for the extraction of copper in these soils.

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