Cationic micronutrient fractions in some tropical Alfisols and Inceptisols as affected by organic amendments and simulated moisture regimes: an incubation study

Abstract

Cultivation of rice is severely jeopardized by the intangible behavior of micronutrients under variable moisture and organics leading to its inconsistent availability. The present study has been conducted to determine the effect of organic amendments and moisture regimes on cationic micronutrients like zinc (Zn), copper (Cu), iron (Fe) and manganese (Mn). Controlled situation incubation study using thrice replicated factorial randomized design with (3 organic amendments × 2 moisture regimes × 2 incubation periods) levels was conducted. Continuous submergence (CS), 50 g kg−1 rice straw and 150 days of incubation (DOI) restored higher soluble and Exchangeable (SE) manganese and iron; while SE-Cu was facilitated under alternate wetting and drying (AWD) condition. SE-Zn was found higher under AWD, no organic administration and 60 DOI. Again AWD, 50 g kg−1 rice straw and 60 DOI recovered higher Mn, Cu, Fe and Zn in organically bound fractions. The adoption of CS, 50 g kg−1 rice straw and 150 DOI recovered higher Mn, Cu, Fe and Zn in manganese and amorphous iron oxide bound fractions; while AWD, no rice straw administration and 60 DOI recovered higher Mn, Cu, Fe and Zn in crystalline iron oxide bound fractions. Substantial change in all the studies fraction resulted into alteration in plant availability of Mn, Cu, Fe and Zn. Under the scenario of global increasing water demands, AWD apart from saving 30-40% moisture improves availability of Cu and Zn which is further accentuated by organic matter, sustaining soil productivity and ensuring food security.