Ontario Grain Farmer November 2021

10 SOIL HEALTH IS a concept that gained traction in the late 1970s and encompasses chemical, physical, and biological soil indicators. Measuring those indicators — and the factors that affect them — is still ongoing today. There is no scientific consensus on the best indicator, however, as explained by Dr. Inderjot Chahal, a soil scientist and post-doctoral researcher at the University of Guelph, soil organic carbon (SOC) and total nitrogen (TN) are currently well-accepted as solid indicators of soil health. Much work has been done around the world to study the factors that can increase soil health and the list is quite familiar. They include different tillage systems (no-till versus fall plow), crop rotation, use of cover crops, and nitrogen (N) fertility treatments. In a recent study at the University of Guelph Ridgetown Campus, Chahal (with colleagues Dr. Bill Deen, Dr. Dave Hooker, Dr. Laura Van Eerd, and Dr. Ken Janovicek) assessed the impact of these factors, using data from research plots collected in 2016. They measured how much each can improve soil health, as well as which factors offer the highest capacity for sequestering SOC and TN over time. Their results were just published in Soil and Tillage Research. Chahal and her colleagues used two commercially available soil health tests called Soil health TESTING AND BUILDING PRODUCTION SYNERGIES Treena Hein IN EARLY SPRING, RED CLOVER GROWTH (FOREGROUND) COMPARED TO NO-TILL AND CONVENTIONAL TILLAGE (BACKGROUND) AT THE LONG-TERM TILLAGE SYSTEM AND CROP ROTATION EXPERIMENT AT THE ONTARIO CROPS RESEARCH CENTRE – MAY 2, 2019, ELORA. PHOTO COURTESY LAURA VAN EERD. Research Solvita CO 2 -burst and Solvita labile amino N (SLAN). “Solvita CO 2 -burst and SLAN are indicators of soil microbial activity. Solvita CO 2 -burst measures the amount of CO 2 produced through soil respiration and SLAN measures the amount of emitted NH3,” she says. “Our results confirm the applicability of these tests to detect differences on the scale of crop phase (short-term), and crop rotation and tillage (long-term). To our knowledge, this is the first independent evaluation of SLAN and Solvita CO 2 -burst as impacted by long-term agricultural management practices such as crop rotation and tillage in a climate like Ontario.” BENEFITS In terms of which cropping practices improve soil health more than others, the team’s results suggest that all are important: diversifying the corn-soybean rotation by integrating small grain cereals (winter wheat, oats, and barley), using cover crops such as red clover and/or perennial crops such as alfalfa. However, Chahal says “I think the most important practice is using cover crops. They provide numerous positive benefits such as increasing soil health, increasing soil carbon storage mainly by adding residue carbon inputs, reducing weed infestation, increasing crop yield, increasing soil microbial activity, and protecting the soil from losses via runoff and erosion. Chahal lists the second most-important management strategy to be integrating small grain-cereals such as winter wheat in crop rotations. “Like cover crops, adding wheat to corn- soybean rotations has shown to be an effective approach for increasing soil diversity, improving soil structure, increasing soil carbon and nitrogen storage, and reducing