Poster Number 990
See more from this Division: S04 Soil Fertility & Plant NutritionSee more from this Session: Nitrogen and Crop Production: II
A five year study was designed to determine the rotation
effect of soybean on corn and the value of both a corn/soybean and
corn/corn/soybean rotation on sandy loams soils. There were four objectives: 1. Estimate
the ‘N credit' of soybean for the following corn crop. How this is
determined depends on several factors, but the economic optimum N rate might be
different by about 11 kg N/ha (10 lb N/ac) when the N rate is determined by the
UNL procedures and a corn/nitrogen price ratio is 8 which is similar to the
long term value ($3.20/bu corn, $0.40/lb N).
2. Determine if there is a
difference in potential yield due to soybean in a corn/soybean and
corn/corn/soybean sequence compared to corn/corn/corn. The 3 year rotation
had very little agronomic effect on the second year of corn, except that there
was about 250 kg/ha (4 bu/acre) more yield than in continuous corn. 3. Determine the effect of continuous
soybean on soybean yields. Continuous soybean yielded 4.10 Mg/ha (60.9
bu/acre) , which was statistically the same, but less
than soybean in the corn/soybean rotation which averaged 4.27 Mg/ha (63.4 bu/ac) over the length of
the experiment. Soybean every third year
averaged 4.17 Mg/ha (61.9 bu/ac). Since continuous soybean is unlikely, the
difference between soybeans every other year and every third year is minimal,
and beyond the precision of this experiment to differentiate. However, we only
measured the second cycle of the rotation. A longer experiment might find differences
increased over time. 4. Determine the
effect of nitrogen application during early reproductive stage(R1)
to soybean. There was no yield response to nitrogen in any of the five
years. Average yields were 4.31 Mg/ha (64 bu/ac) where no nitrogen was applied,
which was the highest yielding treatment compared to the average of the other
nitrogen applications.
See more from this Session: Nitrogen and Crop Production: II