Monoculture Agriculture Leads to Poor Soil Health

October 5, 2021 | Soil and soil quality are declining rapidly in the U.S. and around the world, with recent data indicating that the U.S. Corn Belt has lost 35% of its topsoil. “Understanding the management practices that lead to healthier soils will allow farmers to grow the same crops while reducing costly chemical inputs (fertilizers, pesticides, herbicides) and protecting the environment,” said study coauthor Lori Phillips, PhD in a study published in Agrosystems, Geosciences and Environment. Researchers analyzed a long-term cropping system that includes 18 years of continuously grown soy, corn, and perennial grasses. Each cropping system was evaluated for its bacterial and fungal population, as well as a test called CNPS, which measures the enzymes produced by microbes specifically related to the soil’s carbon, nitrogen, phosphorous, and sulfur cycles. Researchers indicate that these measurements create “a holistic measure of biological activity.” Within the perennial grasses, the community consisting of red fescue and birdsfoot trefoil (a legume) is found to contain healthier soil than a system with only tall fescue grass. Both soil organic matter and CNPS activity are higher for the grasses than for the monoculture crops by 2- or 3-fold. Microbial communities are also markedly different between monoculture crop and perennial grass soils. “Intensively managed agricultural soils, with more frequent tillage and high fertilizer inputs, tend to be dominated by bacteria. In contrast, more sustainable management practices increase the overall amount of fungi in soil,” Dr. Phillips notes. [Pérez-Guzmán, Lumarie et al. An evaluation of biological soil health indicators in four long-term continuous agroecosystems in Canada. Agrosystems, Geosciences and Environment. June 2021]