Bi‐directional hoeing in maize

Abstract

The weed control efficacy (WCE) of mechanical weeding in the inter‐row area in conventional cropping systems can achieve more than 90%. Despite the use of special intra‐row tools (e.g., finger weeders), only a WCE of 65%–75% can currently be realized in the intra‐row area. To close the gap between inter‐row and intra‐row WCE, in this study, a new approach for high‐efficacy precise mechanical weeding is presented. By using a GPS‐based pneumatic precision seeder (Kverneland GEOseed), a square crop seeding pattern of 37.5 cm × 37.5 cm was established in maize to enable post‐emergence hoeing lengthwise and transverse to the sowing direction. Thus, the treated area by the hoeing blades is postulated to increase, resulting in higher WCE. For this, six field experiments were conducted in South‐Western Germany in 2021 and 2022. Goosefoot blades and no‐till sweeps were guided automatically using a camera for row detection and a hydraulic side‐shift control for the hoe. This bi‐directional treatment was compared to an herbicide application and to hoeing treatments only along and transverse to the sowing direction. The bi‐directional hoeing treatment increased the WCE compared to hoeing along the crop rows on average from 80% to 95% and was not significantly different from the herbicide applications in 2022. Precise sowing in combination with hoeing along and transverse the crop rows resulted in 5.3% crop losses compared to 2.2% for hoeing only along the sowing direction by using only 15 cm wide goosefoot blades, while in the herbicide treatment and the untreated control no crop losses were detected. While maize biomass was not significantly different from the herbicide treatment in most cases over both years, in 2022, even the grain yield of the bi‐directional hoeing treatment with goosefoot blades (7.8 Mg ha−1) was statistically equal to the herbicide treatment (6.9 Mg ha−1). This study demonstrates the great potential of bi‐directional hoeing as an effective alternative to chemical weed control in row crops such as maize, sunflower and sugar beet.