Efficient use of urea for potatoes grown on acidic brown hill soils of Simla

Field experiments were conducted on the acidic brown hill soils of Simla to find (i) the safe dose of urea application to the soil with rellpect to tuber germination, (ii) the best combination of soil and foliar application of urea for getting higher tuber yields and (iii) the improvement in the efficiency of urea by neem cake and a slow acting form of urea (DMU). In three years out of four years of experimentation, application of urea up to 80 kg N/ha to the soil was a safe dose to the germinating tubers but in a wet year, the germination was affected. However, the harmful effects of urea on tuber germination could be obviated by applying it with neem cake in the ratio of 3: 1 on N basis. The combination also improved the efficiency of urea in the terms of tuber yield. Application of urea in slow acting form (DMU) and calcium ammonium nitrate did not affect the germination. Application of urea @ 20 kg N/ha to the soil and @ 20 kg N/ha to the foliage in two equal instalments at 60 and 70 days of plant growth gave higher tuber yields than 40 kg N/ha as urea applied either to the soil of foliage. The efficiency of urea was also increased by applying it in the slow acting form and the effect was pronounced in a wet year.