Yield, nutrient uptake and soil nutrient balance in wheat (Triticum aestivum) as affected by nutrient omissions in cotton (Gossypium spp)-wheat cropping system

Balanced fertilization is one of the key input for maintaining productivity and sustainability of the food production systems. For assessing the impact of nutrient omissions on grain yield, nutrient uptake pattern, soil nutrient balance and fertilizer requirement for targeted yield of wheat (Triticum aestivum L.), a field experiment on nutrient omission plot technique was conducted during 2010-11 and 2011-12. The treatments comprised omission of nitrogen, phosphorus, potassium and zinc, 50% omission of N, P, and K, absolute control (no nutrient applied) and optimum nutrition (150-26.4-50-15-3 kg/ha of N-P-K-S-Zn). The reduction in the grain yield due to N, P and K omission was 35.0%, 9.6% and 3.0% during the year 2010-11, which further increased to 49%, 11.5% and 7.4% during the year 2011-12, respectively. The reduction in N, P and K uptake was more drastic in the N omission treatment, mainly due to the reduced dry matter accumulation. The agronomic efficiency (AE) and apparent recovery (AR) of N, P and K was higher when applied at 50% of their recommended level. On the basis of the indigenous supply, nutrient uptake and apparent recovery efficiency (AR) of N, P and K estimated in this study, the N:P2O5:K2O dose needed to attain a yield target of 4.5, 5.0 and 5.5 tonnes/ha wheat grain yield worked out at 155:37:45, 188:79:83 and 220:106:121 kg/ha, respectively. Omission of P and K resulted in a significant increase in the small grain screenings (<1.8 mm).