EFFECT OF DIFFERENT FORMS AND RATES OF NITROGEN FERTILIZATION ON THE SOIL POLLUTION BY NITRATE AND ITS ACCUMULATION IN POTATO AND ECONOMICS OF EXPORT

Abstract

Tow field experiments were carried out in Gemmeiza agricultural research Station, ARC Ministry of Agricultural during two successive summer seasons of 1998 and 1999 using Nicola potato cultivar to investigate the effect of nitrogen forms as ammonium sulphate, ammonium nitrate and urea at levels of 140,180,220 and 260 Kg N/Fed. of each form. Results of this study indicated that application of nitrogen as ammonium sulphate increased vegetative growth character viz fresh and dry weight/ plant, stem length, number of branches, number and weight of tubers/ plant, chlorophyll a & b of leaves and total tuber yield followed by urea and ammonium nitrate. Generally, increasing nitrogen dose increased vegetative growth character. Whereas marketable tuber yield increase noticed beyond 180 Kg N/Fed. While non­ marketable tuber yield increased with increasing nitrogen rates. Leaves nitrate and nitrite concentration changed during the growing season. However, increasing the concentration in leaves and potato tubers were positively correlated with increasing nitrogen fertilizer rates. Application of ammonium nitrate as a source of nitrogen fertilization give the highest concentration of nitrate and nitrite in leaves and tubers compared to the other two nitrogen forms. The dry matter percentage, specific gravity and non- soluble carbohydrate percentage decreased with increasing nitrogen rate.