Since farmers often wonder how stratification affects no-till, Jeff Schoenau tackled a few frequently asked nutrient cycling questions.

A Canadian research scientist located at the University of Saskatchewan in Saska­toon, Saskatchewan, Schoenau offers viewpoints which may fit some U.S. no-till farming situations.

Q: Do the plant nutrients cycle in the same manner and rate when tillage is eliminated?

A: Producers often think they need to change fertilization practices to accommodate nutrient turn­over with no-till. Farmers wonder how plant nutrients, especially nitrogen, are supplied in plant-available forms, such as nitrate and ammonium, during the growing season.

Nitrogen supplied by soil depends on the amount of plant-available nitrogen, the rate at which available nitrogen is released from soil organic matter and the amount of crop residues kept on the ground over the growing season plus losses due to leaching, gaseous escape or even temporary nitrogen tie-up as crop residues decompose.

Eliminating erosion by reducing costly tillage can certainly have a positive effect on a soil’s ability to supply long-term plant nutrients.

Concerns have also risen about release of phosphorus and potassium. Both short-term (next growing season) and long-term (after several years) considerations are important to achieve the maximum benefit from no-till.

Q: With no-till, do I need to adjust fertilizer rates to compensate for changes in soil nutrient turnover?

A: Research suggests no-till will reduce levels of plant-available nitrogen in the first few years. This is due to a reduced rate of soil organic-matter decomposition induced by formation and persistence of macro-aggregates…