Release, availability and geochemical interaction of Fe in soil after long‐term integrated nutrient management in wheat

Abstract

Wheat contributes to about one‐fifth of the total calories and protein consumption by humans but is found lower in total iron (Fe) concentration than the targeted nutritional requirement, leading to increasing cases of anaemia and malnutrition in humans, especially in the developing countries. Therefore, it is the need of the hour to understand the dynamics of Fe in soil and its supply in relation to wheat productivity and grain quality. The objectives of this study were to examine the impact of long‐term (54 years) annual and biannual application of different doses of farmyard manure (FYM) (0, 5, 10 and 15 Mg ha−1) and nitrogen (0, 60 and 120 kg ha−1) under integrated nutrient management on the dynamics of Fe in soil along with its relationship with total Fe uptake in wheat. Additionally, the release pattern of native soil Fe and risk of Fe toxicity were evaluated. The highest grain yield of wheat (6.08 Mg ha−1) was observed under biannual application of FYM and nitrogen at 10 Mg ha−1 and 120 kg ha−1, respectively, which was approximately 155% higher than the control plot (F0N0). Under the dual season application of 15 Mg ha−1 FYM and 120 kg ha−1 nitrogen, the total Fe content (48.48 mg kg−1) and its uptake (270.52 g ha−1) in wheat grains were found at maximum. The soil incubation study revealed that the rate of release of Fe increased up to 30 days of incubation followed by constant rates indicating the establishment of dynamic equilibrium among the different Fe fractions. Thus, the present study was conducted for the first time to improve the understanding of changes in Fe concentration and rate of release in soil, which directly influence the Fe uptake in wheat grain under the long‐term integrated nutrient management practices.