Browsing by Author "Semoka, J. M."

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Pedological characterization and classification of some typical soils in three agro-ecological settings of South-Eastern Tanzania
(IJSER, 2018-02) Tenga, J. J.; Msanya, B. M.; Semoka, J. M.; Semu, E.; Mwongo, S. B.
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 -1 -1 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 -1 -1 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.
Pedological characterization of some typical alluvial soils of Kilombero District, Tanzania
(American Journal of Agriculture and Forestry, 2017-03-02) Kalala, A. M.; Msanya, B. M.; Amuri, N. A.; Semoka, J. M.
This study was carried out in Kilombero District, Tanzania with the objective of characterizing the soils in terms of their morphology, genesis, physico-chemical properties and classification. Three pedons KISA-P1, MKU-P1 and MBA-P1 were identified within the Kilombero Valley, dug, described and sampled. Disturbed and undisturbed soil samples were taken from designated pedogenic horizons for physical and chemical analysis in the laboratory. Using both field and laboratory data soils were classified using both USDA Soil Taxonomy and World Reference Base for Soil Resources schemes of classification. Results show that the three pedons were developed under Isohyperthemic temperature and Aquic moisture regimes. All pedons were deep (100 - 120 cm). Whereas Pedons KISA-P1 and MBA-P1 had sandy clay loam topsoils overlying sandy clay subsoils, Pedon MKU-P1 had clayey texture throughout its profile depth. All pedons had low chromas of . 3 and redoximorphic features in form of abundant mottles particularly in the subsoils. Topsoils of Pedons KISA-P1 and MBA-P1 had dominantly friable to very friable moist consistence while those of Pedon MKU-P1 had very firm moist consistence. Subsoil moist consistence varied from firm to extremely firm (Pedons KISA-P1 and MKU-P1) and from friable to very firm (Pedon MBA-P1). Structures were dominantly weak to moderate subangular blocky in all studied soils but some horizons were structureless single grained and massive. Soil reaction ranged from extremely acid (topsoil of MBA-P1) to mildly alkaline (subsoil of MKU-P1) with pH values of 4.44 and 6.73 respectively. Topsoil organic carbon and total nitrogen contents in the studied pedons were low (0.66 to 1.4%) and very low to low (0.08 to 0.19%) respectively. CECsoil values were rated as low to medium ranging from 8.4 to 23.8 cmol (+)/kg respectively in Pedon KISA-P1 and Pedon MKU-P1. Percent BS values varied between and within studied pedons and ranged from low < 50% to high > 50%. Studied soils manifested nutrient imbalances in respect of basic cations. On the overall, fertility of the studied soils was rated as low to medium. According to USDA Keys to Soil Taxonomy, Pedons KISA-P1 and MKU-P1 classified as Inceptisols, equivalent to Cambisols in WRB for Soil Resources whereas Pedon MBA-P1 classified as Entisols equivalent to Fluvisols. All three sites were recommended for paddy production.