RP-Department of Agricultural Resources Management (ARM)

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Browsing RP-Department of Agricultural Resources Management (ARM) by Author "Bar-Tal, A."

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    Chickpea Residue Properties Controlling Decomposition Dynamics and nitrogen Availability in Some Tropical Acid Soils
    (Taylor & Francis; NISC (Pty) Ltd, 2013) Danga, B. O.; Hadas, A.; Wakindiki, I.; Ouma, J. P.; Bar-Tal, A.
    Chickpea (Cicer arietinum) grown in a rotation can contribute significant nitrogen (N) if its decomposition and nutrient-release dynamics are known and synchronised with the maximum demand by the succeeding crop. The aims of the study were to investigate the decomposition rates of two chickpea residues, mature (CHR) and green manure (GM), and use their properties to predict N dynamics in acid soils. The N dynamics were predicted by the NCSOIL model using neutral and acidic detergent fibres (NDF and ADF, respectively) measured by near-infrared reflectance spectroscopy (NIRS) for defining residue pools. The GM released 50–60% of total N in 84 d, whereas CHR immobilised N. Simulations based on the two residue pools indicated that NIRS predicted the carbon (C) and N dynamics reasonably well for both residues. The decay rate constants of the NDF − soluble pool varied between 0.5 and 0.2 d−1. Adding an intermediate pool NDF  ADF improved the prediction of C and N dynamics for CHR but not for GM. Therefore, successful prediction of N dynamics required the search of N partitioning among pools by NCSOIL, as long as no chemical analysis of N was suitable for this purpose.
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    Wheat Rotation for Higher Production in a Humid Tropical Region
    (Association of Official Seed Analysts, 2010-03) Danga, B. O.; Ouma, J. P.; Wakindiki, I. I. C.; Bar-Tal, A.
    Stagnation in grain production in the developing world has contributed to the current worldwide food crisis. The principle objective of this study was to evaluate the possibility of improving grain production in the tropical humid region by chickpea (Cicer arietinum L.) in rotation with wheat (Triticum aestivum L). A 3-yr field experiment in Kenya included four short-rain-season (SRS) management practices (chickpea green manure [GM], mature chickpea grain crop [CG], tilled fallow [TF], and weedy fallow [WF]), and inorganic N fertilizer at three rates (0, 30, and 60 kg N ha−1). The chickpea treatments decreased SRS water storage at wheat planting by 14 to 16% compared with TF, but this did not affect yield of subsequent wheat. The GM accumulated 77 kg N ha−1 yr−1, compared with 42 kg N ha−1 yr−1 for the CG. The chickpea treatments increased soil available N by 19% and N uptake by wheat by 39% compared with the fallow methods. Inorganic N applications of 60 kg N ha−1 increased soil-available N at 30 d after sowing by 21.4% and N uptake by wheat by 47%. The CG and GM increased the average annual wheat grain yield by 14 and 31% compared with the WF and TF. Inorganic N applications of 30 and 60 kg N ha−1 increased wheat grain yield by 20 and 7%, respectively. The combination of GM with 30 kg N ha−1 gave the highest wheat grain yield, but CG with 30 kg N ha−1 fertilizer was the most profitable practice.