The impact of uprooting and soil‐covering on the effectiveness of weed harrowing

Abstract

The impact of uprooting and covering plants on mortality and growth reduction was investigated in the laboratory using Lolium perenne L. and Lepidium sativum L. (harrowed 3–4 days after emergence) and Chenopodium quinoa Willd. (harrowed at emergence) as model weed species. Although the predominant initial effect of harrowing was to cover the plants, only 1–17% of the non‐uprooted covered plants were killed because the depth at which they were buried by the harrow was shallow. Uprooting was more effective (47–61% mortality) but strongly dependent on soil moisture content. It accounted for 93 and 95% of L. sativum and C. quinoa mortality, but for only 60% of L. perenne mortality. In L. perenne, the species most sensitive to burying, a strong positive relationship was observed between the percentage of plants covered by harrowing and the fresh weight reduction of the total population 6 days after harrowing. The fresh weight reduction of the total L. sativum population was best related to the percentage of uprooted plants, but the percentage of covered plants also appeared to be a good predictor because of its correlation with uprooting. Most of the uprooted plants were also buried. The fresh weight reduction of the total C. quinoa population was not related to the covering effect of harrowing and only weakly related to the percentage of uprooted plants. The results indicate that the plant recovery process after harrowing needs further study and that field research methods should be refined so that they can better discern initial and final harrowing effects on weeds.

Weed harrowing in winter cereal under semi-arid conditions

“…It tills the soil surface superficially, so that weed seedlings are uprooted and covered by soil. Some authors have suggested that the most important effect is covering (Jones et al, 1995), while in other experiments uprooting was probably the main cause (Kurstjens and Kropff, 2001;Cirujeda et al, 2003). Uprooting and covering may not completely kill the weeds, but the damage caused may be enough to slow down their growth (Lambain et al, 1993) although Rasmussen (1992) did not find that surviving weeds had a lower competitive ability.…”

Benefits of Precision Farming Technologies for Mechanical Weed Control in Soybean and Sugar Beet—Comparison of Precision Hoeing with Conventional Mechanical Weed Control

“…Furthermore, additional conditions for application (e.g., temperature, soil moisture, soil texture) have to be satisfied in comparison to chemical approaches. The strong dependency on weather conditions for mechanical weed control has already been shown in Kurstjens and Kropff [30]. Therefore, if mechanical weed control is not applicable or successful, an additional cost-effective chemical measure is necessary.…”

Herbicide Reduction Methods

“…These tools can be used to perform a whole crop cultivation (crop and weed plants), inter-row and intra-row cultivation. Cultivating tillage mainly controls annual weeds through uprooting, tearing plants into pieces and burial of weeds into soil; however perennial weeds are little affected (Jensen et al, 2004;Kurstjens & Kropff, 2001;Kurstjens & Perdok, 2000;Rueda et al, 2010). Since controlling weeds with mechanical tools generally is a trade-off between weed control and crop damage due to cultivation, post-emergence cultivation must be combined with pre-emergence methods to overcome the poor selectivity (Melander et al, 2005).…”