Influence of Water Stress and Split Application of Nitrogen on Changes in Organic Carbon and Macronutrients in Soils Growing Rice on Orthent

An experiment was conducted in pots with loamy Orthent in 1988–89 (rabi season) with rice (cv. Ratna) receiving 100 kgN ha⁻¹ in three splits in three ratios (90: 10:0; 70: 20: 10; 50:30:20) under different water stress conditions. Organic carbon level changedfrom 5.7 to 1.7g kg⁻¹ soil, available N from 130.0 to 30.0 mg kg⁻¹ soil, available P from 19.8 to 6.3 mg kg⁻¹ soil, available Kfrom 218.0 to 94.0 mg kg⁻¹ soil, extractable Cafrorn 1.3 to 3.5 g kg⁻¹ soil, extractable Mg from 3.75 to 29.16 mmol kg⁻¹ soil at different stages of rice crop growth under different water management systems. Submergence maintained highest level of availability of all these nutrients whereas water stress reduced their availabilities.