Investigators at the KBS LTER site find differences in soil carbon gain among cover cropped, no-till, and perennial cropping systems after 25-years. Cover cropping found to be a powerful tool for building soil carbon even in cropping systems that are plowed. No-till and diverse perennial plantings also emerge as effective ways to build long term soil carbon stores.
Soil carbon, often called the foundation of soil fertility, plays a crucial role in enhancing plant water availability, supporting beneficial microbes and insects, improving drainage, and promoting nutrient cycling and retention of critical plant nutrients like nitrogen and phosphorus. Moreover, carbon stored in soil is carbon kept out of the atmosphere. Farming methods that increase soil carbon are a win-win they benefit a farmer economically through increased yield, and help mitigate climate change.
Yet, building soil carbon is a slow and mysterious process. It can take decades to detect measurable carbon change in most agricultural soils. It is also unknown which farming practices will reliably and continually build soil carbon.
This is why results from a 25-year study of soil carbon gain reported this month by scientists at the LTER is so valuable: they show how different farming practices can build soil carbon but to different degrees and at very different rates.
Field crops in a corn-soy-wheat rotation grown conventionally with tillage and no cover crops did not show an increase in soil carbon over 25 years. However, when a winter cover crop was added, these fields sequestered carbon rapidly – increasing by up to 25% over 25 years. Likewise, no-till practices, in which seeds are planted into unplowed soil using specialized equipment, also built soil carbon, but only half as fast as the rate of cover crops.
Dr. Carolina Córdova, lead author of the study and now assistant professor at the University of Nebraska-Lincoln, notes that “We were surprised that cover crops were so effective in building soil carbon, which emphasizes the value of keeping living roots in soil for as much of the year as possible.”
Even more effective than cover crops in these annual systems, soils planted with perennial crops like alfalfa and unmanaged successional vegetation, sequestered carbon even more effectively. This has implications for the role of conservation plantings, bioenergy, and feedstocks contributing to climate change mitigation as well.
The study findings have significant implications for sustainable agriculture. These are practices that should be promoted by policymakers seeking to support farmers as they implement climate-smart agricultural practices that enhance soil health and contribute to climate change mitigation.
Source : msu.edu