World Journal of Agricultural Sciences 8 (2): 208-211, 2012 ISSN 1817-3047 © IDOSI Publications, 2012 Corresponding Author: K. Sivasakthy, Department of Agricultural Chemistry, Faculty of Agriculture, University of Jaffna, Sri Lanka. 208 Organic Nitrogen Sources and Nitrification Inhibitors on Leaching and Phyto-Accumulation of Nitrate and Yield of Amaranthus polygamous K. Sivasakthy and N. Gnanavelrajah Department of Agricultural Chemistry, Faculty of Agriculture, University of Jaffna, Sri Lanka Abstract: Nitrate pollution of ground water and nitrate accumulation in edible tissues are main issues due to heavy doses of nitrogen fertilizer application. A pot experiment with Amaranthus polygamous was carried out in Calcic red yellow latosols (Eutrustox) of Sri Lanka fertilized with urea, compost and poultry manure with and without locally available nitrification inhibitors Azadirachta indica leaf powder or Lantana camera leaf powder to quantify NO -leaching loss and NO -accumulation in edible tissues and yield. Treatments were T (urea), 3 3 1 T (compost), T (poultry manure), T (urea + Azadirachta indica leaf powder), T (compost + Azadirachta 2 3 4 5 indica leaf powder), T (poultry manure + Azadirachta indica leaf powder) and T (urea + Lantana camera leaf 6 7 powder). Completely randomized design was used with three replicates. Analysis of variance and Least Significant Difference test was performed at 5% significant level. Results indicated that poultry manure and compost have potential in terms of reducing NO -leaching loss and reduce NO -accumulation risk in edible 3 3 tissues, compared to urea. Further, reduction in nitrate leaching losses is also possible through incorporation of tested nitrification inhibitors with urea, poultry manure and compost. However, yield was not significantly different in any treatment. Key words: Nitrate Compost Poultry manure Azadirachta indica Lantana camera INTRODUCTION Potential of locally available materials such as Nitrate pollution of ground water due to excess powder as nitrification inhibitor in Calcic red yellow nitrogen fertilizer applications is well known. Heavy doses latosols (Eurustox) of Sri Lanka have already been of N fertilizer usage by farmers and high nitrate in well reported [1, 2]. Moreover, the amount and source applied water used for irrigation, could also lead to nitrate and the time and method of application govern the effects accumulation in vegetables. Organic manure usage could of N fertilizers on nitrate accumulation in vegetables [3]. reduce the potential nitrate leaching problems because It has been reported that synthetic nitrification inhibitors of their slow release of nitrogen. Moreover, nitrification could effectively reduce nitrate accumulation in pasture inhibitors also could be used to reduce nitrification of [4] and vegetables [5] when mixed with nitrogen fertilizers. applied fertilizers and consequently reduce nitrate Though Azadirachta indica leaf powder and Lantana pollution. Vegetables and drinking water are the main camera leaf powder have been identified as nitrification source of dietary nitrate, which is a potential hazard to inhibitors their effect on nitrate accumulation in human and animal health and researchers agree that vegetables has not been studied. efforts to lower nitrate levels in vegetables and drinking On this background an experiment was carried out to water are warranted. study the effect of different sources of nitrogen and their The use of the nitrification inhibitors may retain N combination with locally available nitrification inhibitors in the NH form, that is less susceptible to leaching namely Azadirachta indica leaf powder and Lantana 4 + and thus minimizes N loss. Several compounds have camera leaf powder, on yield, leaching of nitrate and nitrification inhibition property but only a few compounds nitrate content of leafy vegetable Amaranthus have been adopted in agriculture due to their high cost. polygamous under greenhouse condition. Azadirachta indica leaf powder and Lantana camera leaf