[01] W. Shanika, Department of Agricultural Chemistry, Faculty of Agriculture, Eastern University, Chenkalady, Sri Lanka. [02] P. Premanandarajah, Department of Agricultural Chemistry, Faculty of Agriculture, Eastern University, Chenkalady, Sri Lanka.

Since green revolution, over usage of chemical fertilizers became predominate with the concern of food security for the growing population. This indiscriminate usage causes malignant effects on soil fertility especially in sandy regosols where the leaching of nutrients particularly nitrogen causing yield losses as well as environmental and health defects. A pot experiment was carried out at Eastern University, Sri Lanka to evaluate the nitrogen use efficiency, nitrogen uptake and yield of okra (Abelmoschus esculentus (L.) Moench) in sandy regosolusing variety EUOK - 2. The treatment combinations were laid out in Completely Randomized Design and there were thirteen treatments with four replicates. In this experiment poultry manure, farmyard manure, Leucaena (Ipilipil) leaves and paddy straw were used as organic nitrogen sources and urea as the inorganic nitrogen source. The organic manures were evaluated solely and in combination with urea at the rate of 50% and 100% from each in weight basis. These all treatments were tested with control with no organic or inorganic nitrogen sources and were evaluated among themselves also. Significantly highest nitrogen uptake and pod yield were registered in application of sole poultry manure. Nitrogen use efficiency expressed as agronomic nitrogen use efficiency (NUE-AE) and physiological nitrogen use efficiency (NUE-PE) were registered in application of sole farmyard manure and Leucaena leaves respectively. So sole poultry manure, farmyard manure and Leucaena leaves can be suggested to the farmers especially for the cultivation of okra on sandy regosol in order to obtain the best yield and indirectly minimizethe use of synthetic fertilizers.

Okra, Organic Manure, Pod Yield, Nitrogen Uptake, Nitrogen Use Efficiency

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