Farming system effects on biologically mediated plant–soil feedbacks

Abstract

Cropping system characteristics such as tillage intensity, crop identity, crop-livestock integration and the application of off-farm synthetic inputs influence weed abundance, plant community composition and crop-weed competition. The resulting plant community, in turn, has species-specific effects on soil microbial communities which can impact the growth and competitive ability of subsequent plants, completing a plant–soil feedback (PSF) loop. Farming systems that minimize the negative impacts of PSFs on subsequent crop growth can increase the sustainability of the farming enterprise. This study sought to assess the individual and combined impact of the cropping system (certified organic-grazed, certified organic till and conventional no-till) and crop sequence [pairwise rotations with safflower (Carthamus tinctorius), yellow sweet clover (Melilotus officinalis) and winter wheat (Triticum aestivum)] on the PSF magnitude and direction. All cropping systems followed the same 5-year rotation and had completed one full rotation before soil was sampled. In a greenhouse setting, a sterile soil mix was inoculated with field soil collected from all systems and three crops. The PSF study consisted of two stages (conditioning and response phases) that mimicked the rotation stages occurring in the field. PSFs were calculated by comparing the biomass of the response phase plants grown in inoculated and uninoculated soils. The farm management system affected PSFs, inferring that tillage reduction can encourage more positive PSFs. Crop sequence did not affect PSF but interacted strongly with the farm system. As such, the effects of the farming system on PSFs are best illustrated when taken into account with the identity of the previous and current crops of a cropping sequence.

Intercropping red clover with intermediate wheatgrass suppresses weeds without reducing grain yield

“…(2019) reported weed biomass at harvest of approximately 250 kg ha −1 consisting of many of the same species we observed including dominance by roughstalk bluegrass, Italian ryegrass, and field bindweed ( Convolvulus arvensis L.). Total weed biomass in wheat plots increased by an order of magnitude over 3 yr in our experiment, coinciding with declines in wheat performance that might indicate the development of negative plant‐soil feedbacks in the continuous wheat cropping system (Hol et al., 2013; Menalled et al., 2021).…”

Temporal Soil Bacterial Community Responses to Cropping Systems and Crop Identity in Dryland Agroecosystems of the Northern Great Plains

“…A chisel plow, tandem disk, and field cultivator were utilized in the organic tilled treatment as needed to terminate cover crops, prepare the seedbed, and incorporate cover crop residue into the soil (Ishaq et al, 2020a). Targeted sheep grazing at a stocking density of 50 sheep/ha for 30 days terminated cover crops and managed weeds in the organic grazed treatment (Menalled et al, 2020). The agronomic management details are provided in more detail elsewhere [see Adhikari and Menalled (2020)].…”

Las arvenses como hospedantes de microorganismos en un agroecosistema de sucesión Zea mays L.-Phaseolus vulgaris L.

“…Las asociaciones entre las arvenses y los microorganismos del suelo pueden promover aumentos tanto en crecimiento como en la resistencia a patógenos (Menalled et al, 2021). Aunque varios estudios han demostrado el efecto perjudicial de la competencia entre las arvenses y los cultivos, pocos estudios se han realizado con relación a los aspectos microbiológicos.…”

“…Estas condiciones edáficas no garantizan la abundancia y desarrollo funcional de estos organismos (Menalled et al, 2021). Este resultado está en correspondencia con la visión agroecológica que insta a la conservación de la cubierta vegetal en los cultivos.…”