Cover cropping enhances soil microbial biomass, community, and activity: A global meta-analysis

Authors: MUHAMMAD, IHSAN - Northwest University; WANG, JUN - Northwest University; Sainju, Upendra; ZHANG, SHAOHONG - Northwest University; ZHAO, FAZU - Northwest University; KHAN, AHAMAD - Agricultural University Peshawar

Submitted to: Soil Biology and Biochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/27/2020
Publication Date: 9/8/2020
Citation: Muhammad, I., Wang, J., Sainju, U.M., Zhang, S., Zhao, F., Khan, A. 2020. Cover cropping enhances soil microbial biomass, community, and activity: A global meta-analysis. Soil Biology and Biochemistry. 381:114696. https://doi.org/10.1016/j.geoderma.2020.114696.
DOI: https://doi.org/10.1016/j.geoderma.2020.114696

Interpretive Summary: Cover crops provide many agronomic and environmental benefits compared to no cover crops, but their impact on soil microbial communities, biomass, and activity have been variable depending on soil and climatic conditions of various regions. Meta-analysis provides a systematic documentation of the quantification of cover crops on soil microbial dynamics. Researchers at ARS, Sidney, MT in collaboration with Northwest University, Xian, China, and The University of Agriculture, Peshawar, Pakistan reported in a global meta-analysis that cover crop enhanced soil microbial biomass carbon and nitrogen, arbuscular mycorrhizal fungi, actinomycetes, gram-positive and gram-negative bacteria, phospholipid-derived fatty acids, and soil respiration, but had variable effect on fungi compared to no cover crop. Nonlegume cover crop increased microbial biomass carbon, arbuscular mycorrhizal fungi, total fungi, actinomycetes, gram-positive bacteria, and soil respiration compared to legume and mixed (legume + nonlegume) cover crops. Legume cover crop increased microbial biomass nitrogen compared to nonlegume and mixed cover crops. Cover crop enhanced microbial community, biomass, and activity compared to no cover crop and nonlegume cover crop was more effective in enhancing microbial dynamics than legume cover crop.

Technical Abstract: Cover crops have been increasingly grown for improving soil health and crop production and minimizing environmental impact compared to no cover crop. No systematic quantification of cover cropping on soil microbial communities, biomass, and activity, however, are documented in the literature. A global meta-analysis of 43 currently available literature was carried out to elucidate the effect of cover crop on fungi, bacteria, actinomycetes, microbial biomass C and N (MBC and MBN), and soil respiration following cash crops compared to no cover crop. Cover crop enhanced MBC, MBN, arbuscular mycorrhizal fungi (AMF), actinomycetes, gram-positive and gram-negative bacteria, phospholipid-derived fatty acids (PLFA), and soil respiration, but had variable effect on fungi compared to no cover crop. Nonlegume cover crop increased MBC, AMF, total fungi, actinomycetes, gram-positive bacteria, and soil respiration compared to legume and mixed (legume + nonlegume) cover crop. Legume cover crop increased MBN compared to nonlegume and mixed cover crop. The effect of cover crop on MBC was prominent on loam and silt loam soils with soil organic C (SOC) >20 mg g-1 and pH 6.5-7.5 in subtropical region with 10-15oC air temperature and > 1000 mm annual precipitation. Similarly, the effect of cover crop on MBN was prominent on loam and clay loam soils, with SOC <10 mg g-1 and pH 6.5-7.5 in subtropical region with <10oC air temperature and >1000 mm annual precipitation. Although cover crop enhanced microbial community, biomass, and activity compared to no cover crop, nonlegume cover crop favored these parameters more than legume or mixed cover crop.