School of Agriculture, Natural Resources and Environmental Studies

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Browsing School of Agriculture, Natural Resources and Environmental Studies by Author "Agalo, Jerry"

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    Effects of lime, phosphorus and rhizobia on Sesbania sesban performance in a Western Kenyan acid soil
    (2015-07-21) Kisinyo, Peter; Othieno, Caleb; Gudu, Samuel; Okalebo, J. R.; Opala, P. A.; Maghanga, J. K.; Agalo, Jerry; Ng'etich, W. K.; Kisinyo, Joyce; Osiyo, R. J.; Nekesa, A. O.; Makatiani, E. T.; Odee, D. W.; Ogola, B. O.
    Aluminium (Al) toxicity, phosphorus (P) deficiency and low rhizobia populations limit Sesbania (Sesbania sesban) performance in tropical acid soils. The study determined the i) indigenous rhizobia populations that nodulate sesbania and ii) effects of lime (0 and 4 t/ha), P-fertilizer (0 and 60 kg/ha) and acid tolerant rhizobia (0 and inoculation) on soil and selected sesbania accessions performance in Western Kenya acid soil. Study site had acid soil, low available P, nitrogen (N) and rhizobia populations that nodulate Sesbania (146 cells/g soil). Lime increased soil pH, while both lime and P-fertilizer increased available P. Aluminium toxicity tolerant and P-efficient accessions (SSBSA004, SSUG3, SSUG4 and SSUG5) had faster growth, higher nodulation, shoot P, and shoot N and response to treatments than the sensitive one (SSBSA203). After 7 months of growth, SSUG3 had highest shoot length (306 cm) and dry matter (5.64 tons/ha), hence, most suitable for building poles and fuel wood. SSUG5 accumulated the highest shoot N (222 kg N/ha) and was therefore, most suitable soil N replenishment. Thus, in acid P deficient and low rhizobial population soils of Western Kenya, the use of lime, P-fertilizer, rhizobia inoculation and Al toxicity tolerant Sesbania are important for Sesbania establishment and growth. Key words: Rhizobia, Sesbania, soil acidity, aluminum toxicity, lime, phosphorus.
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    Immediate and residual effects of lime and phosphorus fertilizer on soil acidity and maize production in western Kenya
    (2015-08-21) Kisinyo, Peter; Othieno, Caleb; Gudu, Samuel; Okalebo, J. R; Opala, P. A.; Ng'etich, W. K.; Nyambati, R.O.; Ouma, Evans Ochieng; Agalo, Jerry; Kebeney, S.J; Too, E.J; Kisinyo, Joyce; Opile, W.R.
    Soil acidity and phosphorus (P) deficiency are some of the major causes of low maize yields in Kenya. This study determined the immediate and residual effects of lime and P fertilizer on soil pH, exchangeable aluminium (Al), available P, maize grain yield, agronomic P use and P fertilizer recovery efficiencies on a western Kenya acid soil. The treatments were: P fertilizer (0, 26 and 52 kg P ha−1 as triple super phosphate) and lime (0, 2, 4 and 6 tons lime ha−1 ) applied once at the beginning of the study. A burnt liming material with 92.5% calcium carbonate equivalent was used. Soil samples were analysed prior to and after treatment application. The site had low soil pH–H2 O (4.9), available P (2.3 mg kg−1 ), total N (0.17%), high Al (2.0 cmol kg−1 exchangeable Al and 29% Al saturation). Lime reduced soil pH and exchangeable Al, leading to increased soil available P. Lime at 2, 4 and 6 tons ha−1 maintained soil pH ≥ 5.5 for 2, 3 and 4 years, respectively. The study observed that the recommended P fertilizer rate (26 kg P ha−1 ) for maize production in Kenya was inadequate to raise soil available P to the critical level (≥10 mg P kg−1 soil bicarbonate extractable P) required for healthy maize growth. To maintain soil available P at the critical level where 52 kg P ha−1 and combined 52 kg P ha−1 + 4 tons lime ha−1 were applied, it would be necessary to reapply the same P fertilizer rate after every one and two cropping seasons, respectively. The 4-year mean grain yield increments were 0.17, 0.34, 0.50, 0.58 and 1.17 tons ha−1 due to 2, 4, 6 tons lime ha−1 , 26 kg P and 52 kg P ha−1 , respectively. Both agronomic P use and P fertilizer recovery efficiencies increased with increasing rates of lime and decreased with increasing rates of P fertilizer. Therefore, combined applications of both lime and P fertilizer are important for enhancing maize production on P-deficient acid soils in western Kenya.