Kratochvil studying wheat performance after spring nitrogen

COLLEGE PARK, Md. — Research conducted by University of Maryland agronomist Dr. Robert Kratochvil under checkoff funding by the Maryland Soybean Board has been cited by the Maryland Department of Agriculture in the preparation of proposed revisions of the state’s nutrient management regulations.
For four years, Kratochvil sought an answer to this question:
Does a small grain crop, following soybeans, benefit from a spring application of nitrogen?
Each year, Kratochvil reported, wheat was planted following production of six soybean varieties that ranged from maturity from MG 2 to mid MG 4. Soil samples were collected — upon a 6 inch depth — just prior to wheat planting to determine amount of residual nitrate following soybeans.
Each soybean variety plot was divided so that one-half the plot received no fall N fertilizer and the other half received 30 pounds per acre fall N fertilizer.
Soil samples were collected a second time during late winter to assess if differences between the fall N fertilizer treatments existed prior to the application of spring N fertilizer.
On March 1 or as soon as possible following that date, 50 pounds of N per acre of spring N fertilizer was applied to all plots.
A second spring application of 50 pounds of N per acre was supplied to the wheat once jointing growth stage started.
Kratochvil reported no yield response to 30 pounds fall N per acre was observed in whear. Soybean maturity, even though differences in amount of residual soil nitrate had been present, did not affect wheat yield.
“This outcome indicates that supplying fall fertilizer N following soybean has the likely result of that N moving below the root zone of the wheat where the potential exists for it to be lost to groundwater,” Kratochvil told the Soybean Board.
His recommendation: Wheat following full season soybean does not require starter fall N regardless of soybean maturity group the preceding soybean variety represented.
That recommendation is precisely reflected in the proposed nutrient management revision regarding fall fertilization.
It says this:
Nitrogen may not be applied to small grains (wheat and barley) during the fall, in most circumstances. The use of starter fertilizer (for example, fertilizer used when a crop is newly planted) on small grains will be prohibited unless a soil test for nitrates indicates that there are too few nitrates to support the crop. (Those amounts are measured at 10 parts per million of residual nitrate for wheat and 15 parts per million for barley.)
Research conducted by the University of Maryland over four years indicated that fall application of starter nitrogen on small grains neither increased yields nor provided economic returns in the majority of cases tested.
Soil nitrate tests will indicate whether there are inadequate nitrates available.