Abstract
ABSTRACT Groundcover management can significantly affect soil microbial metabolic activities, especially carbon metabolism, in apple orchards. However, there have been few studies on the effects of groundcover on the seasonality of soil microbial carbon metabolism. We, therefore, studied soil microbial carbon metabolism in an apple orchard on China’s Loess Plateau under four single species cover crops (the grass Dactylis glomerata L., and the legumes Trifolium repens, Coronilla varia L., Lotus corniculatus L.) during spring, summer and fall. Cover cropping significantly, but differentially, promoted soil microbial carbon metabolism in spring and fall. However, cover cropping leads to a significant reduction of soil moisture in spring and summer due to the competition of soil moisture between the cover crops and apple trees, which probably lead to the changes in types of carbon substances metabolizing by soil microbes in summer. Besides, cover crop significantly enhanced soil organic carbon contents between three seasons while clean cultivation had slight, non-significant effects. The promotion of soil microbial metabolic activities was probably an important mechanism for the carbon accumulation, and we postulate that leguminous cover plants may have significantly different effects, mediated through their root exudates, from grasses on soil carbon contents.
Highlights
Cover crops have proven utility in conferring benefits to soil with respect to organic matter and allied benefits [1]
To address the knowledge gaps discussed above, we evaluated soil microbial carbon metabolic capacity in an apple orchard three times per year (May, July and October, which reflected three local seasons spring, summer and fall, respectively) after 10 years of interplanting with cover plants to determine how seasonal changes affect soil microbial metabolism under groundcover management in the long term
The results showed that different cover crops would exert different effects to orchard soil microbial metabolic activities, which has been found in other researches when most of these studies focus on using Biolog Ecoplates data to reflect microbial diversity in topsoil rather than soil microbial carbon metabolism [6]
Summary
Cover crops have proven utility in conferring benefits to soil with respect to organic matter and allied benefits [1] In recent years, they have gained considerable popularity within annual cropping, but are underused within perennial systems. On the Loess Plateau of China, where there have been substantial soil organic matter losses, nutrient imbalances and moisture deficits, mulching using cover crops is important for local economies and the environment [3]. This region includes one of the largest apple production areas in China, which produces very high-quality fruits.
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