Integrated management of living mulches for weed control: A review

Abstract

Living mulches are cover crops grown simultaneously with and in close proximity to cash crops. Advantages of living mulches over killed cover crops may include increased weed suppression, erosion and leaching control, soil health, and resource-use efficiency. Advantages of living mulches over synthetic mulches may include enhanced agroecosystem biodiversity and suitability for a wider range of cropping systems. A major disadvantage of this practice is the potential for competition between living mulches and cash crops. The intensity and outcome of mulch-crop competition depend on agroecosystem management as well as climate and other factors. In this review, we consider the management of living mulches for weed control in field and vegetable cropping systems of temperate environments. More than 50 years of research have demonstrated that mechanical or chemical suppression of a living mulch can limit mulch-crop competition without killing the mulch and thereby losing its benefits. Such tactics can also contribute to weed suppression. Mechanical and chemical regulation should be combined with cultural practices that give the main crop a competitive advantage over the living mulch, which in turn outcompetes the weeds. Promising approaches include crop and mulch cultivar selection, changes to planting time, density, and planting pattern, and changes to fertilization or irrigation regimes. A systems approach to living mulch management, including an increased emphasis on the interactions between management methods, may increase the benefits and lower the risks associated with this practice.

Facilitation of weed seed predation by living mulch and cover crops

“…The weed suppressive effect of cover crops is well documented (e.g., Brust et al, 2014; Hartwig & Ammon, 2002) and might even be enhanced by stress or artificial damage through very low dosages of herbicides or harrowing (Gerhards & Schappert, 2020). The management of living mulch needs more attention, since it is grown simultaneously with the crop and can become a competitor (Bhaskar et al, 2021), while cover crops established after the main crop are not competitive. In addition to their direct effects on weed populations, cover crops, living mulches and carabid beetles offer additional ecosystem services, such as pest control (Fourie et al, 2016; Lovei & Sunderland, 1996), reduced erosion (Bhaskar et al, 2021; Hartwig & Ammon, 2002) and nitrogen retention (Finney & Kaye, 2017).…”

“…The management of living mulch needs more attention, since it is grown simultaneously with the crop and can become a competitor (Bhaskar et al, 2021), while cover crops established after the main crop are not competitive. In addition to their direct effects on weed populations, cover crops, living mulches and carabid beetles offer additional ecosystem services, such as pest control (Fourie et al, 2016; Lovei & Sunderland, 1996), reduced erosion (Bhaskar et al, 2021; Hartwig & Ammon, 2002) and nitrogen retention (Finney & Kaye, 2017). Whether repeated stubble tillage is more effective in weed suppression than cover crops is still an open research topic.…”

Effect of Soil Regenerative Practice on Selected Soil Physical Properties and Eggplant (Solanum melongena L.) Yield

“…Intercropping and living mulches can provide important nutrients to support crop yield in the event shortages of organic fertilizer [16]. The latter factor has been gaining increasing and more interest, especially in horticulture, since intercropping can contribute to the reduction of weed infestation [16][17][18] and in pest occurrence [16,19]. Living mulches should also be considered as an important element in the protection of the soil environment against erosion [17,20], as well as a factor reducing the leaching out of nutrients to deeper soil layers and ground waters [21][22][23].…”

Spring-seeded winter rye living mulches enhance crop biodiversity and promote reduced tillage organic soybeans

“…Living mulches maintain both weed suppression and cash crop yield when selected living mulch species have morphological and physiological differences from cash crops that limit competition for light, nutrients, and water (Verret et al, 2017;Bhaskar et al, 2021). Winter rye is an ideal living mulch for soybeans because its life cycle is complementary to soybean's.…”

“…Due to winter rye's vernalization requirement, it will not set seed when spring sown (Bàrberi, 2002;Uchino et al, 2009), precluding issues from rye seedbank or soy seed lot contamination. Winter cereal rye creates a living mulch that is highly competitive with the early season germinating weeds through light interception, soil resource competition, and allelopathic effects (Brainard and Bellinder, 2004;Reberg-Horton et al, 2005;Datta et al, 2017;Vollmer et al, 2020;Bhaskar et al, 2021). However, winter rye begins to senesce as temperatures increase and soybean demand for water and nutrients intensifies, thereby potentially limiting the competitive effects of the living mulch on soybean grain yield (Robinson and Dunham, 1954;Ateh and Doll, 1996;Thelen et al, 2004).…”