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This study was carried out in South-Eastern Tanzania to establish representative experimental sites on the basis of agro-
ecological settings and soils. Three pedons were characterized namely NWJ-P1 in Nawaje village, MKG-P1 in Mikangaula village and
NNL-P1 in Nannala village. Soil moisture and temperature regimes in the study areas were, respectively, ustic and isohyperthermic. Fifteen
soil samples from genetic soil horizons were analyzed for physico-chemical properties. Pedons NNL-P1 and MKG-P1 had loamy sand
topsoils overlying sandy loam to sand clay loam subsoils. Pedon NWJ-P1 had sandy clay loam topsoil overlying clay subsoil with
indications of eluviation-illuviation as dominant pedogenic process. Whereas pedons NWJ-P1 and MKG-P1 were medium acid to slightly
acid (pH 5.91 - 6.35), pedon NNL-P1 was extremely to very strongly acid (pH 4.36 - 4.57). Topsoil OC contents of the soils were very low to
medium (0.49 to 1.28%) while subsoil values were very low to low (0.16 - 0.66%). Total nitrogen in the pedons were very low (0.02 - 0.07%)
while C/N ratios generally ranged from 7 to 18 indicating good to moderate quality of soil organic matter. All studied soils were low in
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available P (< 7 mg kg ) except topsoil of pedon NNL-P1 which had medium values (P range 7- 20 mg kg ). CEC values ranged from very
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low (< 6.0 cmol (c) kg ) to low (6.0 - 12.0 cmol (c) kg ). % base saturation of pedon NNL-P1 was medium (21 - 60) while pedons NWJ-P1 and
MKG-P1 had high values (> 60%). Nutrient ratios Ca/TEB, Mg/K and %( K/TEB) indicated some degree of nutrient imbalance in the soils
likely to impair nutrient availability to plants. According to USDA Soil Taxonomy the pedons classified as Typic Dystrustepts (pedon NNL-
P1), Typic Argiustolls (pedon NWJ-P1) and Typic Haplustepts (pedon MKG-P1) which, according to WRB for Soil Resources, translated
into Dystric Cambisols, Luvic Phaeozems, and Eutric Chromic Cambisols, respectively. In view of the study results, the studied pedons
differed markedly in terms of pedological and physico-chemical properties, emphasizing the need to characterize soils before embarking on
strategies and practices on soil fertility management for enhanced sustainable agriculture production. Sustainable cropping on the studied
soils could be achieved with introduction of technologies suitable for rejuvenating soil fertility such as manuring, crop rotation, proper
management of crop residues, fallow periods, introduction of leguminous cover crops in the farming system and use of fertilizers,
particularly non-acidifying types of fertilizers. |
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