Potential of Cover Crops in Promoting Mycorrhizal Diversity and Soil Quality in Organic Farms

Abstract

Mycorrhizal fungi play a crucial role in agroecosystems with their ability to enhance nutrient and water uptake and aid in weeds and pest suppression. Mycorrhizal fungi have a symbiotic association with plants, one which is highly influenced by the interaction between soil and plant conditions. In this study, we analyzed the potential to increase the density and diversity of mycorrhizal fungi of using four different cover-crops: lablab (Lablab purpureus), sunn hemp (Crotalaria juncea), pearl millet (Pennisetum glaucum), and sudangrass (Sorghum drummondii). We examined changes in the density, diversity and structure of mycorrhizal fungi before and after planting the cover crops. Our results indicate that, while the diversity of mycorrhizal fungi was not influenced by the cover-crop type, different cover crops were associated with changes in the density and structure of mycorrhizal fungi. In addition, the cover-crop type also had an impact on the soil organic matter and nutrient status. Of the four we tested, sunn hempwas associated with higher rates of percent organic matter, abundance of mycorrhiza spores, and specific micronutrients, signaling multiple benefits as a warm season cover crop, especially in organic farms that aim to minimize chemical applications.

Abiotic and Biotic Limitations to Nodulation by Leguminous Cover Crops in South Texas

“…Nonetheless, we did find that enhanced nodulation promotes greater leaf biomass which may in turn promote greater cover crop development and subsequent N fixation in a positive feedback. In farms where synthetic N inputs are unlikely to reach excessively high N levels, leguminous cover crops may assist in maximizing plant-available N while providing other benefits to soil health, such as weed control [67], and soil microbial biodiversity [68,69].…”

Cover crops may exacerbate moisture limitations on South Texas dryland farms

“…These findings suggest that careful attention to cover crop species choice, seeding rates, termination method, and recharge period length can reduce the risk of cover crop associated moisture loss and impacts on subsequent cash crops. Although cover crops can provide tremendous benefits toward improved soil health and soil biology in south Texas (Soti et al 2016;Soti and Racelis 2020), the value of these benefits must be considered carefully against the agronomic implications of soil moisture-the limiting factor of crop success among dryland farmers in semiarid regions.…”

“…The climate of the Rio Grande Valley is similar to other warm, semiarid regions where cover crop-induced moisture deficits have reduced cash crop yields (Unger and Vigil 1998;Kaspar and Singer 2011) and soil moisture is a primary limiting factor for plant growth in this region. Minimal research on cover crops has been conducted in the LRGV and the trials that have been published rely on irrigation and report little on soil moisture effects (Zibilske and Makus 2009;Moran and Greenburg 2008;Soti et al 2016;Soti and Racelis 2020). In other regions where cover crop soil moisture dynamics have been studied in greater depth, cover crops have had mixed impacts on soil moisture and evapotranspiration depending on the context.…”

The effects of field inoculation of arbuscular mycorrhizal fungi through rye donor plants on grapevine performance and soil properties

“…The establishment of cover crops is a sustainable soil management practice that promotes the proliferation of natural mycorrhizal communities (Brígido et al, 2017;Brito et al, 2013;Kabir and Koide, 2000;Soti et al, 2016). Moreover, cover crops are an alternative to herbicides and to soil tillage for weed control, and provide a variety of benefits to the soil, by preventing erosion, improving water holding capacity and infiltration rates (Basche and DeLonge, 2019), and by increasing soil organic matter as well as overall biodiversity (Costello and Daane, 1998;Kim et al, 2020;Steenwerth and Belina, 2008;Vukicevich et al, 2016).…”