If you cut back on tillage, you may need to modify your fertility program, say Montana State University soil fertility specialist Clain Jones and cropping system specialist Kent McVay. They have co-authored a new publication, Nutrient Management in No-Till and Minimum Till Systems, to help northern Great Plains dryland growers make the transition.
"In Montana, we've seen a big switch to no-till,” McVay notes. About half the state's crops are now planted with reduced-tillage systems.
"Both soil nitrogen and fertilizer nitrogen are consumed when stubble residue decomposes, especially when the fertilizer is broadcast on the stubble,” Jones explains. "Also, nitrogen release from organic matter is generally slowed in reduced-till systems, due to less oxygen in the soil, especially in finer soils.
"You can compensate for the reduced availability of nitrogen in the soil by applying more nitrogen fertilizer for the first few years after converting to no-till, especially if you broadcast the fertilizer on large volumes of stubble,” Jones continues.
No-till and minimum-till systems often result in a greater concentration of nutrients near the soil surface, Jones adds. Although the recommended rate of application remains the same among tillage systems, Jones and McVay recommend subsurface banding phosphorus with the seed, or up to 2” below the seed, in reduced-tillage systems.