Need based nitorgen managment of maize (Zea mays l.) Grown in the dry zone of Sri Lanka using a six panel leaf colour chart

Maize growing farmers in Sri Lanka generally practice fixed time N fertilizer application. Due to high variability of soil fertility in maize growing areas, fixed time nitrogen application may not totally meet the crop demand for the nutrient, and hence a need based N management strategy would improve the crop productivity while increasing the efficiency of the fertilizer input. An experiment was conducted at the Field Crops Research and Development Institute (FCRDI), Maha-Illuppalama to evaluate the applicability of Leaf Color Chart (LCC) for need based N management of maize. Experiment was planned to identify the optimum LCC values for different growth stages of the crop and validate the suitability of identified values. Both open pollinated and hybrid varieties were tested with different levels of N (0, 75, 150, 225, 300 kg/ha) to determine the optimum LCC values. Optimum LCC values identified were validated by conducting field experiments covering both seasons. Results revealed that six panel LCC developed for rice could successfully be used for maize and a LCC value of 4.5 could be used as the optimal LCC value in need based N management strategy for maize. This technique increases N fertilizer efficiency of applied N compared to the fixed time N fertilizer management strategy.