By: Rafiq Islam, PhD, Soil and Water Specialist
Sustainable agricultural practices based on increasing cropping diversity with cover crops act as a biological primer to improve functional stability of continuous no-till (NT) with enhanced agroecosystem services. We presented the results of our long-term effects (2004 to 2014) of sustainable agriculture based on continuous corn, corn-soybean (CS) and corn-soybean-wheat (CSW) rotations with or without cover crops (CC) on soil health and crop productivity under NT in the session on “Soil Health Research for Agroecosystems” at the American Society of Agronomy/Crop Science Society of America/Soil Science Society of America International Meetings in Minneapolis, MN, in November 2015. We were invited to present our long-term experimental results on Sustainable Agriculture and Agroecosystem Services as they related to the tri-society international meeting theme of “Synergy in Science: Partnering for Solutions.”
To account for the impact of sustainable agricultural practices on soil health, economic crop yields, and agroecosystem services, our research team members (Wayne Lewis, Yogi Raut, Hasni Jahan, Stacey Reno, Emily Weaks, and Drs. Celal Yucel, Derya Yucel, Kenan, Barik, and Ekrem Aksakal) collected composite soil and plant samples over the years from geo-referenced sites of each replicated plot.
The soil samples were analyzed for microbial biomass, basal respiration, metabolic quotients, enzyme activity and earthworms (as biological soil health indicators); total organic carbon and nitrogen, active carbon and nitrogen, and greenhouse gas emissions (as chemical soil health indicators); and particulate organic C and N, bulk density, aggregate size distribution, and macro-aggregate stability (as physical soil health indicators). Corn, soybean, and wheat yield data were collected and normalized as relative crop yields. The soil and crop data were normalized to calculate soil health, based on both inductive and deductive approaches. Data normalization was performed based on the premise that higher values of soil and crop yield data are better indicators of soil health, except for compaction and greenhouse gas emissions.
Our results showed that low external input with increasing cropping diversity under a continuous no-till system significantly improved soil health with an increase in economic crop yields over the annual plowed cropping conventional tillage system. The impact of increasing cropping diversity was more pronounced with wheat and cover crops under continuous no-till. Soil biological health indicators were found more sensitive than soil chemical and physical health indicators. We observed that when switching to continuous no-till crop rotation, it is essential to use multi-functional cover crops to improve soil health for higher crop yields. We found the improvement in crop yields lagged behind improvements in soil health.