Influence of Selected Soil Properties and Cropping System on Soil Boron Fractions in an Inceptisol of Assam, India

The current research aimed to investigate different boron fractions in diverse cropping systems and assess their relationship with various soil physico-chemical properties. Twenty-four geo-referenced surface soil samples (0-15 cm) were collected from four cropping systems: Rice-Rice, Rice-Fallow, Vegetable-Vegetable, and Plantation crops. The study found that the available boron (ranging from 0.56 to 1.69 mg kg-1) and five boron fractions, including Readily Soluble Boron (0.04-2.41 mg kg-1), Specifically Adsorbed Boron (0.15-1.92 mg kg-1), Oxide Bound Boron (5.18-17.41 mg kg-1), Organically Bound Boron (6.86-20.3 mg kg-1), and Residual Boron (17.73-36.57 mg kg-1), did not significantly differ among the cropping systems. The results revealed that the proportions of these boron fractions in soils followed this order: Readily Soluble B < Specifically Adsorbed B < Oxide Bound B < Organically Bound B < Residual B. Additionally, pH and CEC (Cation Exchange Capacity) did not exert a significant influence on soil boron fractions, while Soil Organic Carbon (SOC) significantly impacted Oxide Bound and Organically Bound Boron fractions. Despite the different cropping systems, there were no significant variations in the various boron fractions. Furthermore, the study identified positive correlations between soil organic carbon and Oxide Bound B, Organically Bound B, Specifically Adsorbed B, and Electrical Conductivity (E.C.). The cropping system did not have a significant effect on the diverse boron fractions investigated in this study.