Nutrient omission effects on yield, water productivity and profitability of maize (Zea mays)

A 2-year field experiment was conducted during the rainy seasons (JulyOctober) of 2012 and 2013 on a non- calcareous alkaline sandy clay loam soil, to (i) assess the effect of omitted nutrients on growth, yield, water pro- ductivity (WP) and profitability of maize (Zea mays L.) crop, and (ii) develop guidelines for the use of soil test crop response (STCR) approach and omission plots, in site-specific nutrient management (SSNM) for targeted and sustained yield of maize in the maize (Zea mays L.)wheat [Triticum aestivum (L.) emend. Fiori & Paol.] cropping system. The experiment comprised 15 treatments, involving application of N (-PKZn), NP (-KZn), NPK (-Zn) and NPZn (-K) to both maize and wheat crops, to maize and to wheat crop only, absolute control (no nutrient applied), recommended rate of nutrients (120, 60, 40, 5.5 kg/ha N, P, K, Zn) and STCR-based application of nutrients (200, 100, 55, 4 kg/ha N, P, K, Zn). The experiment was set in a randomized complete-block design with 3 replications, in fixed plots. Growth and yield attributes were significantly influenced by nutrient-omission treatments and their values were higher when nutrients were applied according to STCR approach. The STCR-based nutrient applica- tion increased dry-matter production and grain yield by 5.9 and 5.7%, respectively over balanced fertilization (rec- ommended doses of NPKZn). Omission of P and K resulted in 9 and 9.7% reduction, respectively, in grain yield of maize. The yield reduction caused by Zn omission was about 3% only. On an average, STCR-based fertilization enhanced water productivity (WP) by over 6.2% compared to balanced fertilization with recommended doses of nutrients. Omission of K in both maize and wheat crops reduced WP by 9.3% compared to recommended doses of NPKZn-applied plot. The highest gross profit of 70,425/ha was also realized from STCR-based nutrient appli- cation.