Impact of wood biochar addition on nutrient leaching and fertility in a rural ultisols of Taiwan.

Abstract

Biochar increases the quality of soil and reduces the leaching of nutrients in highly weathered soils. Little, however, is known about the effects of biochar on degraded soils. Therefore, this study hypothesized that adding biochar helps ameliorate and recover the nutrient status of degraded soils. Our purposes are to quantify the effect of adding wood biochar (WB) on the soil fertility characteristics and water leachate chemistry of a degraded soil. Repacked soil columns that contain 0, 2.0, 4.0, and 8.0% (wt/wt) WB were incubated and leached every ten days for 80 days. On days 0 and 80, soil samples were collected and analyzed for fertility. The results demonstrated that adding WB to the soil increased soil pH, soil total carbon, cation exchange capacity and the amount of Mehlich 3 extractable Mn, but reduced the amounts of exchangeable Na, Ca, Mg, Mehlich 3 extractable Ca, Mg, Cu, and Pb. Adding WB did not significantly influence the amounts of total N, exchangeable K, Mehlich 3 extractable P, K, Fe, and other microelements in the soil. The results of leachates showed that the pH and K concentration increased with the increased amount of added WB, but the conductivity and the concentrations of C, N, Ca, Mg, microelements, NO3^-, and PO4^(3-) decreased. These results reveal that adding WB to a degraded soil substantially reduced nutrient leaching, suggesting that adding WB is an effective means of reducing nutrient leaching. In conclusion, applying WB to soils in Taiwan may yield a win-win situation, involving C sequestration and the potential to improve fertility of degraded clayey soil.