THE EFFECT OF COVER CROPS ON PSNT LEVELS AND CORN YIELDS THE EFFECT OF COVER CROPS ON PSNT LEVELS AND CORN YIELDS IN WYANDOT COUNTY, OHIOIN WYANDOT COUNTY, OHIO

ABSTRACTThis research examined the ability of annual ryegrass, cereal rye and oil seed radish to capture and release nutrients from summer applied swine manure compared to the control of no cover crop. The research design used a random replicated design with two manure application rates and four cover treatments. Manure application on wheat stubble occurred in late August, 2006 and the cover crop plots were seeded in early September, 2006. Pre-side dress nitrogen tests (PSNT) were completed on the soil samples collected in early May and yield data was collected in October, 2007. Analysis of the data showed statistically significant differences (>95%) in the PSNT levels with all cover crops being higher than the plots with no cover. Oil seed radish had the highest available N (40 mg/kg) followed by cereal rye (32 mg/kg), annual ryegrass (29 mg/kg) and no cover (21 mg/kg). The collected yield data also indicated a statistically significant difference (>95%) with no cover (165 bu/a) posting the highest yield followed by oil seed radish (163 bu/a), annual ryegrass (161 bu/a), and cereal rye (158 bu/a). Yield differences were hypothesized to be more of a function of moisture loss through the green cover crops in this drought year than a function of cover crops themselves.

Bruynis,* C. L.Bruynis,* C. L.11, Hoorman, J.J., Hoorman, J.J.2 2 , Fritz, M.H., Fritz, M.H.3 3

11 Extension Educator, Ohio State University Extension, 109 S. Sandusky Ave., Rm 16, Upper Sandusky, Ohio 43351 - bruynis.1@osu.edu Extension Educator, Ohio State University Extension, 109 S. Sandusky Ave., Rm 16, Upper Sandusky, Ohio 43351 - bruynis.1@osu.edu22 Extension Educator, Ohio State University Extension, 3900 Campus Drive, Suite B, Lima, OH 45804 - hoorman.1@osu.edu Extension Educator, Ohio State University Extension, 3900 Campus Drive, Suite B, Lima, OH 45804 - hoorman.1@osu.edu33Manure Management Specialists, Soil and Water Conservation District, 97 Houpt Drive, Suite A, Upper Sandusky, Ohio 43351 – mark.fritz@oh.nacdnet.netManure Management Specialists, Soil and Water Conservation District, 97 Houpt Drive, Suite A, Upper Sandusky, Ohio 43351 – mark.fritz@oh.nacdnet.net

RESEARCH OBJECTIVE

The objective of this research was to determine the ability of annual ryegrass, cereal rye and oil seed radish to take up nitrogen from a summer application of swine manure on wheat stubble fields and release that nitrogen for the following years corn crop.

RESEARCH METHODS A demonstration plot was planted on wheat stubble with 4

treatments including annual ryegrass, cereal rye, oil seed radish and no cover and two swine manure applications (5K, and 10K) applied to each treatment (8 plots, 30 feet each by 300 feet). Swine manure was applied on August, 30 2006 and the demonstration plots was drilled on September 6, 2006. Grass cover crops were killed with Glyphosate product on April 7, 2007 prior to plant jointing. Soil pre-side dress nitrate tests (PSNT) were taken on May 24, 2007 and yield tests were taken October 6, 2007.



RESULTSMean available nitrogen from oil seed radish was significant greater (40 mg/kg) than either cereal rye (32 mg/kg) or annual ryegrass (29 mg/kg) and No cover 921 mg/kg) using an ANOVA statistical method (p<.05). Oil seed radish freezes and dies out during the winter so the nitrogen becomes available as the tuber and plant tissue decomposes. Cereal ryegrass is dormant during the winter and annual ryegrass does not go into dormancy. The spring release of nitrogen is dependant on the carbon to nitrogen ratio of the vegetative biomass and the decomposition rate in the spring and summer. Both annual ryegrass and cereal rye had a higher C:N ratio and a slower release of available nitrogen.

ACKNOWLEDGEMENTS

This project was conducted with cooperation of the Crawford, Sandusky, Seneca and Wyandot County Soil & Water Conservation Districts and a Great Lakes Soil Erosion and Sediment Control Grant.

Annual RyegrassAnnual Ryegrass

Cereal RyeCereal Rye

Oil Seed RadishOil Seed Radish

AVAILABLE NITROGEN (mg/kg)

CORN YIELD (bushels/acre)

Rainfall, soil moisture, temperature, and microbial activity affect the rate of nitrogen availability. The low rainfall slowed down microbial decomposition of the grass cover crops. The soil was also drier on these plots due to transpiration from the actively growing grass plants, decreasing corn yields. Corn yields ranged from 157 to 165 bushels but no cover (165 bu/a) had the highest yield followed by oil seed radish (163 bu/a), annual ryegrass (161 bu/a), and cereal rye (158 bu/a) using an ANOVA statistical method (p<.05).

SUMMARY

1.Oil seed radish had significantly greater available nitrogen (40 mg/kg) than either cereal rye or annual ryegrass.

2.Corn yields were significantly lower on annual ryegrass and cereal rye cover crops compared to no cover.

3.Dry weather and plant transpiration dried out the soil in the plots with grass cover, affecting microbial decomposition of plant nitrogen and corn yields.