College of Agriculture, Banaras Hindu University, Varanasi.
* Extract from the thesis supplicated by the junior author in part fulfilment of the requirements for Master's degree of the Banaras Hindu University in 1956.
Three levels of each of N, P2O5 and K2O were tried in all 27 possible combinations on ‘Patna Red’ variety of onion. Growth was recorded at four stages of life cycle and total yield of bulbs was taken at harvest time.
In the beginning only 40 lbs. nitrogen was required for vegetative growth. Later on growth and yield of onion were maximised with 80 lbs. dose. Phosphorus,. though beneficial during early growth period, reduced growth and yield in the-second half of life cycle due to early maturity of plants. Potash feeding, however, exhibited a negative correlation for bulb development.
Nitrogen fertilization along with P2O5 and K2O dressings stimulated growth in the beginning. The utility of increasing nitrogen and decreasing P2O5/K2O content from 2-nutrient combinations, was emphasised with advancement in age. Potash and phosphorus, when applied together, reduced development and yield of onion.
Of the three nutrient combinations, 40-40-0 was best at 30 days. At 90 and 120 days, 80-0-10 and 80-0-20 mixtures maximised growth, while best yield was obtained with 80-0-0 fertilizer combination. Highest concentrations of P2O5 and K2O in the fertilizer proved toxic.
Maximum profit of Rs. 668.66 per acre was obtained from application of 80 lbs. nitrogen alone while a net loss of Rs. 89.44 was accrued from 20 lbs. P2O5 fertilisation, as against a net profit of Rs. 44.33 from unfertilized plots.
