Cover crop influence on soil enzymes and selected chemical parameters for a claypan corn–soybean rotation

Authors: RANKOTH, L - University Of Missouri; UDAWATTA, R - University Of Missouri; Veum, Kristen; JOSE, S - University Of Missouri; ALAGELE, S - University Of Missouri

Submitted to: Journal of Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/11/2019
Publication Date: 6/15/2019
Citation: Rankoth, L.M., Udawatta, R.P., Veum, K.S., Jose, S., Alagele, S.M. 2019. Cover crop influence on soil enzymes and selected chemical parameters for a claypan corn–soybean rotation. Journal of Agriculture. 9(6):125. https://doi.org/10.3390/agriculture9060125.
DOI: https://doi.org/10.3390/agriculture9060125

Interpretive Summary: Cover crops are believed to improve soil quality including soil chemical and biological properties. However, the short-term benefits are not well understood, and studies conducted in real farmer fields are lacking. With on-farm research, the management and field conditions may differ from small scale research plot studies. Thus, this on-farm study was conducted to evaluate the effects of cover crops after four and six years. Several soil quality measurements were taken at different landscape positions and soil depths both with and without cover crops. Although some soil quality indicators increased with cover crops over time, results were inconsistent between years, across landscape positions, and with soil depth. The findings from this study emphasize the importance of long-term farmer field studies with standardized management and sampling protocols to confirm the benefits of cover crops. This work benefits landowners and agency personnel participating in on-farm research programs and provides insight into potential challenges associated with determining the short-term benefits of cover cropping practices.

Technical Abstract: Cover crops (CC) are believed to improve soil quality including soil microbial enzymatic activities and soil chemical parameters such as pH and organic matter content. Scientific studies conducted in research centers have shown positive effects of CC on soil enzymatic activities, however studies conducted in real farmer fields are lacking in the literature. The objective of this study was to quantify CC effects on soil microbial enzymatic activities (ß-glucosidase, ß-glucosaminidase, fluorescein diacetate hydrolase, and dehydrogenase) under a corn (Zea mays L.)-soybean (Glycine max (L.) Merr.) rotation. The study was conducted in 2016 and 2018 at the Chariton County, Cover Crop Soil Health Research and Demonstration Farm (CCSH), Missouri where CC were first established in 2012. All tested soil enzyme levels were significantly different between 2016 and 2018, irrespective of the CC and NCC treatments. In 2016, ß-glucosaminidase activity was significantly greater at the 0-10 cm depth in CC compared to NCC. Significantly greater (P<0.05) ß-glucosaminidase activity was found in CC treatment compared to NCC in 2018, reflecting 1.3 times higher ß-glucosaminidase activity in CC relative to NCC. In contrast, dehydrogenase activity showed significantly greater levels in NCC treatment compared to CC in 2018. All enzyme activities significantly decreased with increasing soil depth, while landscape position was not significant for enzyme activities. In addition, soil pH and % organic matter were found to be significantly greater in CC compared to NCC in 2018. This study highlights the short-term influence of cover crops on soil enzyme activities and illustrates the high spatial and temporal variability of enzymes under farmer managed fields. Thus, more long-term research is required to understand the variability of soil enzyme activity and the impact of cover cropping practices.