Colored plastic mulch impacts on soil properties, weed density and vegetable crop productivity: A meta-analysis

Soil degradation, climate change, and water scarcity worsen the declining crop productivity. Plastic mulches provide a sustainable solution, yet comprehensive evaluations of their effects, particularly in vegetable production, remain limited. This meta-analysis synthesizes 97 studies and 789 observations across 25 vegetable species to assess the influence of plastic mulch colour on crop yields and soil properties. Ten plastic mulch colors were analyzed: black, blue, green, gray, yellow, transparent, white, silver, brown, and red. Results show that all mulch colors improved crop productivity and soil parameters compared to non-mulched soil. Green (effect size (ES) = 5.73, confidence interval (CI) = 3.92-7.93), transparent (ES = 6.52, CI = 5.17-7.87), and black (ES = 1.95, CI = 1.49-2.42) mulches produced the highest significant increase in yield, plant height, and stem diameter, respectively. The highest reduction in weed biomass occurred with red mulch (ES = -9.04, CI = -13.33--4.76). Increases in soil temperature and water use efficiency were noted from black (ES = 0.82, CI = 0.69-0.94) and silver (ES = 0.68, CI = -3.16-4.53), while the black (ES = 0.19, CI = 0.03-0.35), blue (ES = 2.62, CI = 0.44-4.80), and gray (ES = 2.03, CI = 0.06-4) mulches exhibited improved soil organic carbon, pH, total nitrogen, available phosphorus, and potassium, respectively. Besides black, the impacts of other colors are still under-explored, which limits the understanding of their effects on soil properties. Further studies are essential, as soil chemical characteristics are essential in agricultural productivity.