Global Meta‐Analysis of Cotton Yield and Weed Suppression from Cover Crops

Abstract

Cover crops can reportedly improve soil fertility, suppress weed growth and pest pressure, and contribute to cotton (Gossypium hirsutum L.) yield improvements. To systematically evaluate cover crop effects on cotton yield and weed suppression, we conducted a random‐effects meta‐analysis investigating 10 moderating variables in 104 articles, yielding 1117 independent studies over 48 yr. Globally, cover crops increased cottonseed and lint yield by 6 and 5%, respectively, while decreasing weed biomass by 20%. Overall, leguminous cover crops increased seed cotton yield by 17 to 43% (Vicia spp. and Pisum spp., respectively). Monocots, nonlegume dicots, and legumes were effective at suppressing weed growth (21, 52, and 10%, respectively). Incorporation of cover crops by tillage (rather than chemical burn down) resulted in lint (14%) and seed (42%) yield increases. Cover crops increased cotton yields markedly on loamy soils, whereas there were lesser increases for other textures (p > 0.05). Greater efficacy of cover crops at controlling weeds was proportionate to soil silt content, which was inversely related to sand content. In addition, cover crops were effective at controlling multiple types of weed species; however, weed species with shorter maximum heights were most suppressed by cover crops. Overall, cover crops had a positive effect on cotton yield and weed suppression. Their effectiveness, however, can vary depending on soil texture, management strategy, and cover crop or weed genera. These results are useful in developing recommendations for suppressing weed growth and improving yield via cover crop integration in cotton cropping systems per geographic region and soil texture.

Does diversifying crop rotations suppress weeds? A meta-analysis

“…We then eliminated studies where rotational diversity was enhanced only by inclusion of a non-harvested cover crop. While cover crops increase the diversity of crop rotations, our goal in this study was to examine rotations that increased diversity via harvested crops; other meta-analyses have looked specifically at cover crop-weed interactions [18, 19]. No screening was done with respect to the type of crop harvested (grain, fruit, tuber, root, and forage biomass were included).…”

Cover crops improve early season natural enemy recruitment and pest management in cotton production

“…Differences in predator responses to cover crop treatments may be attributed to the type, and quality of resources provided by the cover crop, but also cover crop biomass. Quantity of cover crop residue influences weed suppression and other ecosystem services provided by cover crops (Toler et al, 2019;Finney et al, 2016;MacLaren et al, 2019). Thus, the significantly improved initial biomass of the rye cover crop (Table 1) may explain its increased effectiveness in promoting and harboring a high density and diversity of natural enemies.…”

Dynamics, diversity and experimental precision in final irrigated rice testing: a time meta-analysis

“…Although the magnitude of these values does not differ between the models on a larger scale, the results from the simple model could be misinterpreted, due to the direction of the slope value. According to Toler et al (2019), changes in the study effect could potentially result from publication bias, changes in the methodology or from real biological changes.…”

“…This kind of analysis is a statistical approach to combine multiple, independent studies, carried out under experimental conditions that differ in terms of growing season, location, soil texture, timeframe and other aspects, to assess the consistency of results (Fisher 2015, Toler et al 2019. Meta-analyses are extensively used, exploiting information compiled in systematic reviews, particularly in the field of medicine.…”