Effects of Lettuce Growth and Carbon Sequestration by Different Application Methods with Excessive Amount of Wood-based Agricultural and Forestry By-product Biochar

Abstract

Biochar is typically applied at rates of 2-4 t ha-1; however, its excessive application has been limited due to potential negative impacts on crop productivity, despite its benefits for carbon sequestration. This study examined the growth characteristics of lettuce (Lactuca sativa L.) by applying 20 t ha-1, which is ten times the conventional biochar application rate, using both band-application (B-BC) and overall-application (O-BC) methods to maximize carbon sequestration while maintaining crop productivity. The results showed that lettuce yield was highest in the B-BC (15.7 t ha-1), followed by the Control (14.2 t ha-1), and lowest in the O-BC (7.8 t ha-1). The absorption of Fe, Mn, Cu, and Zn in lettuce leaves and roots was lower in the O-BC due to its higher pH (>7.67) compared to other treatments. Greenhouse gas (GHG) reduction in both biochar treatments was 33.62 t ha-1, which is ten times higher than the conventional application. Furthermore, B-BC increased yield by 10.58% and 101.67% compared to the Control and O-BC, respectively. Therefore, the band-application method is effective in enhancing carbon sequestration and improving crop productivity with excessive biochar application.