Saini, Sat PalMandeep Kaur2019-07-102019-07-102019http://krishikosh.egranth.ac.in/handle/1/5810113519The present study was conducted to investigate the effects of rice straw (RS) incorporation on P and Zn availability in surface (0-15 cm) soil under rice-wheat cropping sequence. The treatments were N application (0, 90, 120 and 150 kg ha-1, main plot) and RS incorporation (0, 5, 7.5 and 10 t ha-1, sub plot).Inorganic-P was dominating fraction (92% of total-P), while organic-P constituted only 8%. Relative preponderance of inorganic P fractions followed an order: calcium bound P (Ca-P) > aluminium-P (Al-P) > iron-P (Fe-P) > reductant soluble-P (Red-P) > saloid-P. Nitrogen and RS incorporation significantly (p<0.05) increased the concentration of inorganic P fractions, with highest concentration in RS10 and N150 treatments. The sequential extraction procedure for Zn fractionation showed the dominance of residual fraction (Res-Zn), and their relative abundance in the surface soil followed an order: water soluble and exchangeable Zn (WS+EX-Zn) < specifically adsorbed Zn (SpAd-Zn) < manganese oxide bound Zn (MnOx-Zn) < organic matter bound Zn (OM-Zn) < amorphous iron bound Zn (AFeOx-Zn) < crystalline iron oxide Zn (CFeOx-Zn) < Res-Zn. These Zn fractions were significantly increased with graded levels of RS incorporation. Increase in P fractions showed a linear positive relationship with SOC and available-P in soil. Zinc fractions were positively and linearly correlated to SOC and DTPA-Zn concentration. Maximum wheat grain yield was observed with N120 and RS7.5 treatments. Highest P and Zn uptakes were observed under RS10 treatment. These results showed that N application and RS incorporation significantly increased the P and Zn concentration in soil under rice-wheat cropping system.ennullThesis