Biochar Addition to the Loam Soil of Soybean Fields Can Reduce Trifluralin Usage in Velvetleaf Control

Abstract

Biochar, made by the pyrolysis of various organic materials such as plants, can amend soil physicochemical properties and improve the efficiency of pre-planted incorporated (PPI) herbicides. The excessive consumption of PPI herbicides results in environmental predicaments; improving the PPI herbicides’ efficacy by changing the soil’s biological properties might solve this problem. Trifluralin, a PPI, is recommended against annual broadleaf weeds such as velvetleaf in soybean fields. In the present study, the treatments included normal soil (NS) (sand 30% + silt 35% + clay 35%) and manipulated soil (MS) (sand 27% + silt 32% + clay 32% + biochar 9%). Two blocks of NS received the recommended dose (RD) (1.7 L/ha) (NS + RD) and a reduced dose (1.2 L/ha) (NS + ReD) of trifluralin. Meanwhile, the block of MS was exposed to the reduced dose (MS + ReD) of trifluralin. Two days after the herbicide treatments, the seeds of Abutilon theophrasti were sown. Then, seven days after sowing, the growth of the weeds was monitored and the weed control percentage was calculated using the arcsine model based on observed data. The results showed that the NS + RD was the most effective treatment in velvetleaf control (100%), followed by MS + ReD (93.5%) with no significant difference. The NS + ReD treatment resulted in 81% weed control showing significant differences with the NS + RD and MS + ReD. Thus, it seems that biochar acts as a neutral buffer and decreases the necessity of PPI herbicide application in soybean fields. Biochar application can potentially reduce soil contamination, weed resistance, environmental pollution, and the adverse effects of PPI herbicides on the soil microbial population.

Keywords

• biochar
• herbicide
• loam soil
• sustainable agriculture
• weed control