Requirement of nitrogen, phosphorus and potassium fertilizers for wheat cultivation under irrigation by municipal wastewater
This study quantified the optimum doses of nitrogen (N), phosphorus (P) and potassium (K) fertilizers for wheat (Triticum aestivum L. cv Shatabdi) cultivation under irrigation by municipal wastewater (here after called wastewater). Separate experiments were conducted with the three nutrients, applying each at five different doses and the other two at the recommended doses. An equal amount of irrigation by wastewater was provided to each experiment. The spike length, spikelets per spike, grain yield and harvest index of wheat increased with the increase in N dose up to 100 kg ha-1, but decreased with further doses. Most of the growth and yield attributes improved significantly (p = 0.05) with the increase in P dose up to 20 kg ha-1, beyond which the P exerted negative, but insignificant, effect on the crop attributes. The omission of N or P significantly reduced the yield attributes and yield of wheat, with the dominant effect of N. Either the omission or the higher than the recommended dose of K had no significant suppressing effect on the grain yield of wheat. The crop most effectively utilized the nutrients when supplied at the lower doses. The omission of N or P or K minimally reduced the 1000-grain weight. The negative effects of the excess nutrient doses were the greatest for N and least for K, implying that N was the most limiting and K was the least limiting factors for wheat production.