Yield of and nutrient-water use by maize exposed to moisture stress and K fertilizers in an inceptisol of West Bengal, India

Potassium (K) is important for both qualitative and quantitative traits of maize. However, role of this macronutrient is often being ignored, and is often applied as an optional nutrient, with no proper fertilizer recommendation. Present experiment focused on the role of K fertilization in determining soil K fractions, maize yield, K and water use by maize under different irrigation regimes. Result revealed that K-fertilization significantly improved available soil K, fractions of K (especially non-exchangeable, mineral and total fractions), maize yield, K uptake and water use efficiency. Imposition of moisture stress up to 50% available soil moisture deficit (ASMD) significantly increased all the aforementioned parameters over the no stress situation, while irrigation available at 75% ASMD reduced them significantly. Soil K fractions, under different K fertilizations and irrigation schedules, decreased with the increase in soil depth upto 90 cm. Only exception was non-exchangeable soil K which remained stable across soil depths. The relationship among different K fractions and available soil K was estimated. Available K was observed to have strongest correlation with water soluble and exchangeable K in all possible irrigation regimes. Path analysis studies revealed that water soluble K exerted highest direct effect on changes in maize grain yield and K uptake followed by exchangeable, non-exchangeable and mineral K under irrigation availability at 25 and 50% ASMD. However, exchangeable K exerted highest direct effect on maize grain yield at 75% ASMD.