Effect of thiourea on nitrogen-use efficiency by potato in Shimla hills*

Greenhouse and field studies were carried out on brown hill soils of Shimla (Palehumults) during 1980–83 to evaluate the effect of thiourea on N nutrition in potato cv. Kufri Jyoti and also on soil fertility. In field study, application of thiourea had a positive effect on tuber yield (32.5%) and N-uptake (66.1%) compared with the control. Optimum N dose was little affected by thiourea levels. N recovery was 10.0–11.5% higher in presence of thiourea. In greenhouse, thiourea application increased the total dry matter yield, uptake of N, P and S by potato. Nitrogen: sources do not differ significantly with regard to dry matter yield and nutrient uptake by potato. After 2 years, thiourea application increased the NO₃-N content in soil by 11.9 to 12.8 ppm.