NEWS for North Dakotans
Agriculture Communication, North Dakota State University
7 Morrill Hall, Fargo, ND 58105-5665
September 21, 2000
Conservation tillage, or any crop residue management system that leaves at least 30 percent of the ground surface covered with residue, includes stubble mulching, ridge tilling, no-till, strip tillage and reduced tillage.
According to Denise McWilliams, extension crop production specialist for North Dakota State University and the University of Minnesota, these systems often improve soil organic matter, available phosphorus and potassium, soil pH and soil water-holding capacity. Over the long term they may also prevent soil erosion and improve overall soil tilth.
Organic matter is important for soils, says McWilliams, because it affects water-holding capacity, nutrient exchange, density and tilth of soils and may also affect nitrogen availability and exchange. A 3 to 4 percent increase in organic matter may increase water-holding capacity in soil by 200 percent and nutrient exchange capacity by 400 to 500 percent, as well as allow nitrogen release through mineralization of as much as 50 to 55 pounds per acre per year.
There is a difference in soil types, she says. Conservation tillage can improve yields on droughty or erosive soils. However, performance is less satisfactory on poorly drained soils that remain wet and relatively cold in the spring.
McWilliams says long-term benefits of conservation tillage can be difficult to measure, but it does appear to have cost advantages compared to conventional tillage. She cites a study in Canada that compared shallow tillage with cultivator sweeps and use of sweeps plus herbicide application to conventional tillage. Labor costs were lower with both sweeps and sweeps with herbicide, while using seeps with herbicide or herbicide alone also reduced fuel and oil use.
Stubble from a previous crop can have an adverse effect on the next crop, especially if the same crop is planted again. She advises crop producers to compare information on cropping rotations to decide what rotation is best for a particular field.
Some crops respond better to conservation tillage. Winter wheat responds better than spring-planted grains. Other crops such as sunflower and corn respond well with adequate nitrogen and moisture. Continued cold, wet conditions in the spring can affect all of these crops, however. Small-seeded crops such as alfalfa, grass and flax perform well under no-till as long as the seed is placed in the proper environment and growing conditions.
Crops that require relatively warm soil conditions to germinate and long growing seasons usually respond less favorably to no-till residue management, McWilliams says.
###
Source: Denise McWilliams, (701) 231-8160
Editor: Gary Moran, (701) 231-8160