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Tillage
Restoring Soil Quality and Productivity in Sustainable Agroecosystems
Timothy M. Harrigan, Ph.D.
Biosystems and Agricultural Engineering
Michigan State University
East Lansing, MI
Many crop producers are beginning to sense a yield drag that they can’t pin down with a single, clear-cut cause. Because soil compaction has been a hot topic in the last several years a question I often hear is “What tillage tool should I use?” While tillage may be a part of the solution, more often than not producers are surprised when I tell them “You can’t till your way out of soil quality problem.” No-tillers are even more surprised when I tell them “You can’t no-till your way out of a soil quality problem.” The soil environment is a complex and interrelated web of physical, chemical and biological factors. There is no single tillage tool that will repair a soil quality problem. The key to building soil quality is in managing the farming system with soil quality in mind.
The development of cropping systems that reduce tillage intensity, increase the use of cover crops and make efficient use of manure in the crop rotation can protect the environment and improve soil quality in many ways. Low-disturbance tillage and soil conservation practices that stabilize soil will keep soil nutrients in place and protect water quality. Cover crops prevent erosion and filter contaminants in runoff. They have also been shown to improve water-stable aggregation of soil and increase water infiltration compared to soil without cover crops (McVay et al., 1989). As soil aggregation improves, soil structure and tilth also improve (Allison, 1968).
At Michigan State University we are developing a new process—manure slurry-enriched seeding—that uses low-disturbance tillage, manure application and cover crops in one efficient operation. The results have been very encouraging and have revealed new opportunities to integrate manure in the cropping system. Productive soil is quite resilient. The soil quality problems that we see today did not occur overnight, neither will the solution. Look for opportunities to reduce tillage intensity and add organic inputs with cover crops and manure. Give the soil a chance.
