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Fertigation in rice-based cropping systems is catching up the attention of farmers for producing high yield of crops and improved fertilizer use efficiency. As fertigation with different combinations of irrigation and nitrogen (N) levels can interact with depth of rooting system of different crops as well as soil tillage, this study was carried out in 2017 in the fourth year of on an on-going long-term experiment initiated in the summer (Kharif) season of 2014 to understand the effect of fertigation on soil organic carbon pools and yield in zero-till direct-seeded rice-based cropping systems. The experiment was laid out in a split plot design with three levels of fertigation as main plots: N @ 20 kg ha−1 in rice through fertigation followed by 200 mm irrigation in post rice crops (W1), N @ 40 kg ha−1, in rice through fertigation followed by 300 mm irrigation in post rice crops (W2), N @ 60 kg ha−1, in rice through fertigation followed by 400 mm irrigation in post rice crops (W3). The sub-plot treatments consisted of zero till direct seeded durum wheat, barley, chickpea, linseed, lentil and lathyrus crops after rice. The rice crop was also under zero till direct seeded cultivation system. The highest grain yield of rice was observed in the rice-lathyrus cropping system with treatment W3 where N was applied in three equal splits, first being basal application and the two subsequent applications through surface inline drip irrigation. Both in surface and sub-surface soil layers, soil carbon stock, carbon pools and aggregate associated carbon were found to be more in the legume based cropping systems and with W3 fertigation regime than in other cereal based cropping systems. The grain yield was found negatively and highly significantly correlated with less labile pool (r=-0.63**) whereas very labile pool was positively significantly correlated with labile (r = 0.89**), less labile (r = 0.53**) and non-labile (r = 0.91**) pools of carbon. Overall, fertigation levels influenced the crop yield and soil organic matter in zero-till direct-seeded rice-based cropping systems. [ABSTRACT FROM AUTHOR]

Lower utilization efficiency of phosphorus (P) in soils is a major setback for the agricultural sector. The objective of this study was to investigate the effect of compost enriched with Rock phosphate on fractions of P in soil and how these forms affect the bioavailability of P in Rice. P fertilization was performed with the enriched compost and compared with rock phosphate and a conventional P fertilizer i.e. single superphosphate (SSP). We conducted a field experiment at Bihar Agricultural University, Sabour with Rice as the test crop in a randomized block design. Chemical P fractions were estimated through sequential fractionation and biomass production and P concentrations in plant parts were measured to estimate the plant P uptake. Yield, yield attributing parameters and P uptake in straw and grain were observed to be affected significantly by the addition of P enriched compost along with 50% recommended dose for P with the total recommended dose for N and K, when compared to absolute control. The alkaline nature of experimental soil seemingly improves the solubility of P from various fractions and the use efficiency of rice, which favors P uptake which was evidently the factors that contributed to these results. The percentage contributions of different fractions to the total P content in soil after paddy harvest were observed to be in the order: Labile-P < Fe/Al-P < Ca-P < residual P. Combined application of P enriched compost and inorganics sustained crop yield and enhanced P uptake in Rice when compared with sole application of chemical fertilizers. [ABSTRACT FROM AUTHOR]