Does conservation tillage on partially reclaimed sodic soil restore land degradation by influencing boron dynamics, bioavailability for plant's uptake and nutritional security?

Boron (B) is nutritionally important for plants, humans and animals but its deficiency in soil and plants has become a global problem and may affect the nutritional quality of food. The widespread crop residue (CR) burning on farms is another environmental and land degradation problem, causing ecological threats to agriculture. Addressing these issues, a field experiment was initiated for B restoration by incorporating CR into partially reclaimed sodic soil under conservation tillage (zero or reduced tillage) and the results were compared with conventional tillage practices. We studied extensively the B-dynamics, bioavailability, interaction with soil properties, uptake in rice and wheat, and plausible contribution in human dietary intake, upon consumption of rice and wheat. Results indicated that zero tillage and CR retention on the soil surface had a significant impact on soil B fractions. The readily soluble B, organically bound B varied from 0.1% to 2% and 11.8% to 39.4% of total B, respectively, and hot water extractable B was found highest in zero tillage. Readily soluble B had significant (p < 0.05) negative correlation with pH (r = -0.54), clay (r = -0.64), and CaCO3 (r = -0.54). The highest B uptake was noticed in rice under zero tillage, where CR was retained on the soil surface. Dietary intake of B was assessed in terms of estimated daily intake, which was maximum in heavy activity men (0.0166 mg kg(-1) d(-1)), conform to 0.02 mg kg(-1) d(-1), as prescribed by the World Health Organization. Thus, the study suggested that conservation tillage may be instrumental in the restoration of land degradation by building B in soil and contributes to nutritional security.