Browsing by Author "Semoka, J. M. R"
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Item Maize yield response and nutrient uptake after micronutrient application on a volcanic soil(American Society of Agronomy, 2006-07-12) Lisuma, Jacob B; Semoka, J. M. R; Semu, EMicronutrients, which are often deficient in volcanic soils, together with macronutrients may lead to higher yields in these soils. A study was conducted under pot and field conditions to identify and correct some micronutrient constraints in a volcanic soil at Mpangala, Tanza- nia, for optimization of maize (Zea mays L.) yields. Dry matter (DM) yields, plant B, Cu, and Zn concentrations, plant B, Cu, and Zn uptake, and grain yields were used to assess the effects of micronutrient treatments. In pots, B, Cu, and Zn fertilizers were applied separately to the soil at two levels, 0 and 2 mg B kg 21 , 0 and 5 mg Cu kg 21 , and 0 and 10 mg Zn kg 21 , in combination with constant rates of 240 mg N kg 21 or 160 mg P kg 21 fertilizers. A higher rate of 320 mg P kg 21 was also included to assess the adequacy of the basal P rate used. A second pot study attempted to establish an optimum rate of Cu under glass- house conditions; rates ranging from 0 to 20 mg kg 21 Cu were tested. Copper significantly (P 5 0.05) increased both maize DM and grain yields; the estimated optimum rate was 20 mg Cu kg 21 under glass- house conditions. This high rate is thought to be due to the high Cu- fixation capacity of volcanic soils. Boron and Zn were sufficient for normal plant growth. We conclude that maize production can be in- creased considerably in Mpangala and other similar soils in the same agroecological zone by applying N, P, and Cu at rates of 120, 80, and 10 kg ha 21 , respectively.Item Pedological Characterization of Some Typical Soils of Busia County, Western Kenya: soil Morphology, Physico-chemical Properties, Classification and Fertility Trends(2014-06-24) Kebeney, S. J; Semoka, J. M. R; Msanya, B. M; Ng’etich, W. KStandard soil survey was carried out in Western Kenya to establish representative research sites on the basis of landforms and other physiographic attributes. Soil profiles were characterized at Emalomba (Nambale District) designated (EMA-P1) and at Bukhalalire (Butula District) named BUMA-P1. Both pedons formed from in-situ weathering of granitic rocks under ustic moisture and iso-hyperthermic temperature regimes. Fourteen soil samples from genetic horizons were analyzed for physico-chemical properties. Both pedons had dark brown sandy clay and sandy clay loam topsoils overlying dominantly clayey subsoils. Both pedons indicate clay eluviation-illuviation as adominant pedogenic process with strong acidic soil conditions and available phosphorus of < 7 mg/kg soil. Organic carbon (OC) is high in EMA-P1 and medium to very low in BUMA-P1 while total nitrogen is medium and low to very low. EMA-P1 and BUMA-P1 have C/N ratios of 8.6 - 9.6 and 12.9 - 24.8 respectively. Both pedons have low to very low exchangeable bases with cation exchange capacity (CEC) < 16 cmol(+)/kg soil. CEC clay values in both pedons are < 24 cmol(+)/kg with BUMA-P1 having < 10 cmol(+)/kg. Both soils are highly weathered with BUMA-P1 depicting more advanced stage of weathering. In the USDA Soil Taxonomy, EMA-P1 was classified as Kanhaplic Haplustults and BUMA-P1 as Typic Kandiustults, both corresponding to Haplic Cutanic Acrisols in WRB. As regards soil fertility trends, OC showed positive correlation with calcium and magnesium indicating organic matter as the main source of plant nutrients. The two pedons differed noticeably in terms of physico-chemical characteristics emphasizing the need to characterize soils before fertilizer recommendations are made. Organic fertilizers are recommended to increase organic matter content and intercropping of cereals with nitrogen fixing legumes to enhance nitrogen in the soils. Use of non-acidifying inorganic fertilizers and lime as soil amendments should also be considered to correct acidity.