ISSUE 13 August 12, 2010
USING WHEAT YIELD AND PROTEIN RESULTS TO MODIFY FUTURE N RECOMMENDATIONS
Wheat yields are generally down from last years records, due to summer heat, and protein levels are up. But not on every farm. Growers and their consultants should use the results from this year to modify their N rates and ways they apply N in the future. Some growers are finding that fall-applied N on sandier soils did not perform in both yield and protein the way that their spring-applied N fields did. This should be a sign that the long-held rule that fall-applied N be reserved for loam and heavier soils is a good rule. Growers farm more land than they did in the past, and it is clear that all of the land may not be well-managed using the same N application methods.
If growers split fields using post-N application to enhance either yield or protein, these results also need to be examined. Take into account the rainfall after the application and consider how likely it would be to receive rain in the future during this time.
If large portions of the field started lodging pre-flowering, this is a sign that the N rate may be too high on that farm or at least in those portions of the farm that lodged. Lodging in grain after flowering did not hurt yield or quality and the combines we have presently do a good job of picking the grain up. Fields that lodged after flowering due to high winds/storms are probably at near the correct N rate for those farms. Check the protein levels, and if they are higher than 15%, then perhaps the N rates could be shaved a little.
Lower protein/yield in fields with surface applied urea should be critically examined to see how well these practices worked. With the early-season rains that many areas experienced, the efficiency of surface-applied urea was probably greater than in most years. In the future, as in the past, practices need to be changed to place N below the soil surface in no-till fields.
SOIL TESTING SHOULD BEGIN NOW
If you review current soil testing recommendations, you
will see there is no sampling date adjustment. A review of experiments sampling
weekly or biweekly from harvest to spring, weather permitting, showed that in
some fields nitrate went up, in some nitrate went down and in some the nitrate
levels were stable. A fall soil test is a snap-shot in time. There is no time
that the value is stable forever. That considered, a fall soil test ANYTIME is
better than no test at all. As revealed in the wheat N recommendation review and
revision, soil test nitrate is an important part of the N recommendation for
wheat and for every N-requiring crop. As soon as the small grains are removed, a
soil sampler should be called. If itís not supposed to rain for awhile, give the
sampler a couple days to sample the field before working the land. The sampling
results will be much better in the surface soil than if you call after chiseling
There is no need to wait until mid to late September to call the sampler. Do it now.
NDSU Soils Specialist