Effect of composted farmyard manure and nitrogen fertilizer on growth and yield of maize (zea mays L.)
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Fertilizer use in Kenya and Africa has been on a declining trend, because of high maize production-input prices relative to output price. With increased prices of fertilizers there is a need for maize production guidelines on altemative fertility management technologies for fanners. Manure is the most effective and affordable material for supplying plant nutrients (Siderus and Muchena, 1977) and its efficient management may be a cornerstone for sustainable agriculture. Field experiments were conducted at Manor House Agriculture Centre, Kitale, Kenya to determine the influence of farmyard manure (FYM) alone or in combination with nitrogen (N) fertilizer on soil fertility, maize growth and yield under field conditions. The experiments were laid out in a randomized complete block design with four replications over two seasons during the long rains (April - September 1998) and st;hl rains (October 1998 - March 1999). Treatments consisted of non-fertilized (control), .5 ton FYM/ha + 45 kg N Iha, 5 ton FYM/ha + 30 kg N/ha, 7.5 v" ton FYM/ha + 15 kg N/ha, composted FYM ®OnJha dry weight) and recommended inorganic fertilizers (60 kg Iha and 60 kg P20s/ha). The inorganic phosphate fertilizer was applied as diammonium phosphate (DAP). Inorganic nitrogen ( ) fertilizer was applied as calcium ammonium nitrate (CAN). The FYM was hand-broadcasted and incorporated into the experimental plots one week before planting in both seasons. Soil pH and nutrient levels (% C, % N, P, K, Ca, Mg, Mn, Na), maize growth, grain yield and yield components were measured. The results revealed that the residual effect of inorganic fertilizers on soil nutrients was not superior to that of FYM treatments. The effect of the treatments on the yield components was translated into the final grain yield. The average maize grain yield was 10.8 and 4.3 ton/ha in first and second seasons, respectively. FYM and N interactions increased yields up to 53% and 41% over the control during the first and second crop seasons, respectively. FYM alone increased yield by 45% and 8 % over the control during the first and second crop seasons, respectively. Approximately equal yields were obtained in maize fertilized with 7.5 tons FYM/ha + 15 kg N/ha, 5 ton FYM/ha + 30 kg N/ha, 60 kg P20slha + 60 kg Iha, 1G tons FYM/ha, whereas low yields were observed with 2.5 ton FYM/ha + 45 kg N Iha and the control. Overall maize yield was 60% lower in season II compared to season 1. This work has revealed the usefulness of using FYM as a basal fertilizer that can substitute for inorganic basal fertilizers in maize growing with equally good results. The slow-nutrient (nitrogen) release from organic manure appears to supply the plant demands throughout the growing period. It can, therefore, be concluded that application of FYM improves crop yields, but may not have much beneficial effect on the fertility status of the soil. The results further reveal that use of recommended inorganic fertilizers does not lead to an increase in yield comparable to the FYM treatments. An economic study is needed to determine the cost especially labor of FYM use and to help identify types of farming systems within which FYM is likely to be beneficial to the farmer in increasing and sustaining soil fertility.