Reference strips, N-Rich strips or N-Ramps can provide wheat and other crop farmers vital information for accurate nitrogen fertilization in season. N-Rich strips have enough nitrogen applied to guarantee non-nitrogen-limited conditions. N-Ramps include small rate studies in fields. Growers can use sensors or visual determination to gauge nitrogen need.
Oklahoma State University offers the following guidelines for establishing reference strips.
– Pick a location that best represents the entire field.
– Strips may be placed in multiple areas of a field.
– Do not place the strips in the best or worst part of the field.
– Put out the strips at or before sowing the crop.
– Wheat strips can be put out a month before sowing.
– Don’t wait until mid-December to put the strips in.
– Apply a pre-plant fertilizer, approximately 40 pounds of nitrogen per acre for grain only and 80 pounds of nitrogen per acre for dual-purpose wheat.
– Producers can band fertilizer with seed and reduce pre-plant rate.
– Don’t skip applying preplant fertilizer unless soil test nitrogen is high.
For in-season analysis of reference strips, OSU recommends:
– Try to sense as close to hollow stem as possible.
– Can sense earlier if days where GDDs (number of days since planting that temperatures were warm enough for wheat to grow) greater than zero are more than 80.
– Don’t sense early if little forage has been produced.
– Use the sensor for most accurate nitrogen rate prescription.
– Growers may use visual determination for N-Ramps.
– Don’t waste money by not using N-Rich strips or N-Ramps.
For dual-purpose wheat, growers should pull cattle off two weeks before sensing. They may choose to fence off areas around strips for two weeks prior to sensing. They should not pull off cattle and sense the same day.