Influence of soil residual boron on rice performance and soil properties under conventional and conservation rice-wheat cropping systems

Application of boron (B) to wheat in conservation rice-wheat cropping systems may have a residual effect that improves productivity and grain quality of the following rice crop. Two field experiments were conducted to evaluate the effect of soil residual B on the performance, grain quality and grain yield of rice and soil biological properties under puddled transplanted (PuTR) and direct-seeded (DSR) rice systems on silty loam soil. A preceding wheat crop was sown using two different tillage systems, plough tillage (PTW) and no tillage (NTW), in combination with four B application treatments: Control (no B), soil application (SA, 1 kg ha^-1), seed priming (0.01 M), and foliar spray (0.01 M). After wheat harvest, rice was planted in PuTR and DSR systems. The conservation tillage system in both wheat and rice (NTW-DSR) significantly increased soil organic carbon (by 18%) and soil microbial biomass carbon (by 5%) over conventional tillage systems (PTW-PuTR). Improved soil health and availability of soil residual B in the NTW-SA-DSR system improved grain yield (by 23-37%) and grain quality (grain protein by 3-8%, amylose content by 26%) over PTW-PuTR irrespective of B application method. Best economic return and net benefit were recorded in the order NTW-SA-DSR & PTW-SA-DSR & NTW-SA-PuTR. Thus, the application of B to NTW had a strong residual effect on grain quality and profitability of the following rice crop. In rice-wheat cropping systems on a silty loam soil, conservation tillage systems (NTW-DSR) significantly improved the availability of soil residual B and soil health and increased economic return.