Effect of Biochar Amendment on Nitrate Leaching in Two Soil Types of India

Abstract

Nitrate leaching from agricultural soils is a major concern to the groundwater, surface water bodies, and environment and also affects the farmers’ economy. The present study investigated the effect of native soil organic carbon and biochar amendment on the leaching of nitrate using a laboratory column study. The experiment was conducted taking two soil types of central India (Inceptisol and Vertisol differing in soil texture, viz. Loamy and clay texture). In each soil type, three native SOC levels (C 1: high SOC, C 2: medium, and C 3: low SOC) and four biochar amendment levels were taken in three replications in a factorial design. The four levels of biochar amendment were 0 (B 0), 5 (B 5), 10 (B 10), and 20 (B 20) g biochar kg−1 of air-dry soil. There was a significant effect of soil C (p < 0.01) and biochar (p < 0.01) amendment on the NO3 −-N leached, and the total dissolved salt (TDS) leached in both soil types. In the Inceptisol, NO3 −-N leaching increased with reduction in native SOC content, whereas the reverse trend was observed in the Vertisol. Biochar amendment reduced NO3 − leaching in both the soils, though the effect was higher in the Inceptisol. In both the soils, a significant effect of SOC level on leachate pH was observed with reducing pH with decrease in SOC level. As compared to control, the extent of reduction in the TDS leaching varied from 13 to 18% under biochar amendment in the Inceptisol and by about 5–6% in the Vertisol.