Research in Michigan’s Huron County indicates response to phosphorus application to corn

Huron Conservation District staff studied the effect of starter phosphorus on two fields. The field with higher fertility showed no response to added phosphorus. The field with more moderate fertility levels may have increased yields with added phosphorus.

In 2008, the Huron Conservation District established a long-term plot to study the effect of reducing phosphorus inputs. The plot has been in a soybean-corn rotation, except for 2010 when it was planted to wheat to allow for tile drainage installation. In 2011, the plot was planted to corn.

There are two different fields within the plot. The “front” field has very high fertility levels: P 143 p.p.m. - K 139 p.p.m. - organic matter 2.90% - CEC 14.19 - pH 7.0. The “back” field has moderately high fertility levels: P 37 p.p.m. - K 112 p.p.m. - organic matter 1.95% - CEC 9.66 - pH 7.7.

After wheat was harvested in 2010, the field was tiled, and 100 pounds per acre of 0-0-60 was broadcast and chisel plowed in. The field was leveled and cover-cropped using one bushel of wheat.

The plot was no-till planted into growing wheat on May 31 and June 1, 2011. Glyphosate was sprayed on June 3. Glyphosate plus Status was sprayed on July 7. The hybrid used was Pioneer 38M60. Three gallons of thio-sol and one pint of zinc and manganese per acre was applied with the starter.

The treatments in 2011 included phosphorus at 0, 10, and 48 pounds per acre applied as a starter. Each treatment was replicated four times in the front field and four times in the back field.

Huron Conservation District staff report that the wheat cover crop caused shading of the crop. Also, there was a fair bit of compaction from the tiling, and there was a field day associated with the tiling which added to the compaction. The spring weather was cool and wet.

Corn was harvested on November 3, 2011. Following are the yield results.

Front Field Results
Treatment Yield (Bu./A) Test Weight Moisture (%)
0# P 177 55.4 21.5
10# P 178 55.1 21.0
48# P 180 56.1 22.0
Average 178 55.5 21.5
Back Field Results
Treatment Yield (Bu./A) Test Weight Moisture (%)
0# P 168 54.4 22.7
10# P 173 54.3 22.6
48# P 172 55.3 22.4
Average 171 54.7 22.6

There were no statistics ran on the results.

The yield results on the front field (the field with greater fertility levels) appear to be similar, regardless of phosphorus treatment. There was a three-bushel difference between the zero rate and 48-pound rate treatments.

The yield results on the back field are a bit different. The two treatments where phosphorus was included are similar, differing by only one bushel. The treatment with zero phosphorus was four or five bushels less than those that received phosphorus. It appears that applying 10 pounds of phosphorus per acre may have increased yields this year under conditions noted earlier in this article.

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