The Impact of Grazing Winter Annuals on Soil Compaction and No-Till Corn and Soybean Yield

Feeding hay during the winter months in Missouri is expensive. Rye and ryegrass have been cost-effective options to feeding hay or stockpiled tall fescue (Bishop-Hurley and Kallenbach, 2001). Winter rye (Blevins et al. 1971) and ryegrass (Jung et al., 1991; Sollenberger et al., 1984) have been used as cover crops to reduce soil erosion (Griffith et al. 1986), improve soil structure and organic matter, weed suppression (Barnes and Putnam 1981; Barnes and Putnam 1986; Creamer et al. 1996;), reduce nitrate leaching, and alter physical and chemical soil characteristics (Lal et al. 1991; Mitchell and Teel 1977; Worshman 1990). Since farmers in the Midwest often experience winter annual weed problems, these producers may be missing an opportunity to integrate winter annual forages into their production system.

Soils in Northern Missouri do not remain frozen throughout the winter months. These soils may be wet during the spring. This moisture provides conditions for excellent spring growth of winter annual forage grasses. Grazing cattle during these conditions may increase soil compaction and require spring tillage to remedy compaction problems. However, limited research has quantified the impact of grazing on claypan soil compaction and the subsequent impact on grain crop yields. This research was initiated to determine the effect of grazing winter annuals on soil compaction and no-till corn and soybean yield compared with non-grazed winter annual treatments.

Research was conducted at the Greenley Research Center near Novelty, MO in 2003, 2004, and 2005. A split-split plot design with grazed and non-grazed winter annuals as the main plot, corn and soybean as the sub-plot, and winter annual forages (Forage Master winter rye, P25R37 winter wheat, King annual ryegrass, Marshall annual ryegrass, and non-treated winter annual weeds) as the sub-sub plot. Treatments were 10 by 50 ft with four replications. Six to eleven cow-calf pairs were used to spring flash graze the plot area for two to five days to simulate a management intensive grazing system. Forage samples were harvested from the non-grazed plots and mowed. Samples were dried and dry weights recorded to calculate forage dry weight yield. All residue was left on the soil surface of the non-grazed plots to prevent nutrient removal. Winter annual forages were harvested once the winter annual forages reached 8 to 10 inch heights.

Winter annuals were planted September 21, 2002. Winter rye and wheat at 120 lbs/a and annual ryegrass at 30 lbs/a were drilled in 7.5 in. rows. Ammonium nitrate was broadcast applied at 50 lbs N/a on September 19, 2002 and March 10, 2003 at 40 lbs N/a to all winter annual forage plots. Winter annuals were harvested and grazed on April 5, April 18, and April 29, 2003. Glyphosate at 22 oz/a plus ammonium sulfate at 17 lbs/100 gal was applied as a burndown application on May 15, 2003. ‘DK C60-19’ was planted at 27,000 seeds/acre in 30 in. rows on May 19, 2003 and fertilized with 150-60-80. ‘Asgrow 3701’ was planted at 180,000 seeds/acre in 15 in. rows on May 19, 2003.

King and Marshall ryegrass were broadcast seeded at 30 lbs/a into standing corn and soybean on September 12, 2003 and August 13, 2004. Forage Master winter rye and P25R37 winter wheat were no-till drilled at 110 lbs/a on October 7, 2003 and October 25, 2004 which was followed by a broadcast application of 50-60-100 in 2003. Ammonium nitrate was broadcast applied at 40 lbs N/a in the spring to all winter annual forage plots in 2003. The entire plot area was fertlilized with 90-60-80 on March 1, 2005. Winter annuals were harvested and grazed on January 20, April 6, April 21, and May 4, 2004. In 2005, winter annuals were harvested on April 19 and May 2, 2005.

A burndown application of Roundup WeatherMAX at 22 oz/a plus ammonium sulfate at 17 lbs/100 gal was broadcast applied following the final grazing. ‘DK C60-19’ corn seed was planted at 26,100 seeds/acre in 30 in. rows and fertilized with 160-80-120. ‘Asgrow 3701’ and ‘DK 38-52’ soybean was planted at 180,000 seeds/acre in 15 in. rows in 2004 and 2005, respectively.

Soil penetrometer readings were recorded during mid-July in 2003 and 2004 at seven, two-inch depth intervals and ten subsamples/plot. No penetrometer evaluations were recorded in 2005 due to drought conditions throughout the summer. Corn and soybean plots were harvested with a small plot combine and moisture adjusted to 15 and 13%, respectively, prior to an analysis. All data were subjected to analysis of variance and means separated using Fisher’s Protected LSD at p=0.05. Main effects were presented when there was an absence of interactions.

Forage yields were similar following corn or soybean residue in 2003 and ranged from 1.35 to 2.73 ton/acre (Table 1). Corn grain yield was 7 to 15 bu/a greater in the non-seeded winter annual weed only treatment when compared to winter annual forage grasses in 2003 while soybean grain yield was similar amongst winter rye, annual ryegrass, and the non-seeded control. Penetrometer resistance to the 6 inch depth was greater in the corn and soybean grazed treatments when compared to the non-grazed treatments (Table 2). Corn grain yield was 12 bu/a greater in the non-grazed treatment while soybean grain yield was 3 bu/a greater in grazed treatment in 2003.

Winter annual forages were harvested four times in 2004 (Table 3). Winter annual dry weight yield was similar following corn and soybean residue except for the wheat. Dry weight yields ranged from 0.68 to 1.62 ton/acre. Winter annual weeds produced as much dry matter as some of the winter annual forages evaluated in this research. Corn and soybean grain yields will be determined this fall.

Winter annual forages were grazed two times in 2005 with dry weight yields ranging from 0.31 to 0.82 ton/acre (Table 5). King and Marshall ryegrass had poor establishment in standing soybean in 2005. This was probably due to the prolonged drought followed by relatively cold, wet weather. There was no difference in corn or soybean grain yield following the winter annual forages and the non-treated control. Similarly, there was no effect of grazing on corn or soybean grain yields in 2005 (Table 6).

In summary, grazed winter annuals have resulted in increased penetrometer resistance in the top 6 inches of soil. This has resulted in a reduction in corn grain yield in two of three years of research and a variable effect on soybean grain yields. There was no increase in corn grain yield following ryegrass, wheat, or winter rye when compared to the non-treated control. A reduction in corn grain yield has been observed following winter rye. Soybean grain yields following winter annual forages have usually been similar to the non-treated control. An economic analysis needs to evaluate the forage and crop yields of grazed winter annuals compared with non-treated, non-grazed crop production land.

References:
Barnes, J. P. and A. R. Putnam. 1986. Evidence for allelopathy by residues and aqueous extracts of rye (Secale cereale). Weed Sci. 34:384-390.

Barnes, J. P. and A. R. Putnam. 1983. Rye residues contribute weed suppression in no-tillage cropping systems. J. Chem. Ecol. 9:1045-1057.

Bishop-Hurley, G.J. and R.L. Kallenbach. 2001. The economics of grazing beef cows during winter. In Proc. American Forage and Grassland Council. 22-25 April 2001. Springdale, AR. Georgetown, TX. pp. 274.

Blevins, R. L., D. Cook, and S. H. Phillips. 1971. Influence of no-tillage on soil moisture. Agron. J. 63:593.

Creamer, N. G., M. A. Bennett, B. R. Stinner, J. Cardina, and E. E. Regnier. 1996. Mechanisms of weed suppression in cover crop-based production systems. HortScience 31:410-413.

Jung, G. A., J. A. Shaffer, and J. L. Rosenberger. 1991. Sward dynamics and herbage nutritional value of alfalfa- ryegrass mixtures. Agron. J. 83:786-794.

Lal, R., E. Reginer, D. J. Eckert, W. M Edwards, and R. Hammond. 1991. Expectations of cover crops for sustainable agriculture. In [W. L. Hargove (ed.)]. Cover crops for clean water. Proceedings of International Conference, Jackson, TN. 9-11 Apr. 1991. Soil and Water Conservation Society of America, Ankeny, IA. pp. 1-11.

Mitchell, W. H. and M. R. Teel. 1977. Winter-annual cover crop for no-tillage corn production. Agron. J. 69:569- 572.

Sollenberger, L. E., W. C. Templeton, Jr., and R. R. Hill, Jr. 1984. Orchardgrass and perennial ryegrass with applied nitrogen and in mixtures with legumes. 2. Component contributions to dry matter and nitrogen harvests. Grass Forage Sci. 39: 263-270.

Worsham, A. D. 1990. Weed management strategies for conservation tillage in the 1990’s. In J.P. Mueller and M.G.Wagger, eds. Conservation Tillage for Agriculture in the 1990’s. Raleigh, NC: North Carolina State University Special Bulletin 90-1. pp. 42-47.

Table 1. Winter annual forage, corn, and soybean yields in 2003.

Table 2. The effect of grazing winter annual forages on penetrometer resistance and subsequent grain crop yields in 2003.^a

Table 3. Winter annual forage, corn, and soybean yields in 2004.

Table 4. The effect of grazing winter annual forages on penetrometer resistance and subsequent grain crop yields in 2004.^a

Table 5. Winter annual forage, corn, and soybean yields in 2005.

Table 6. The effect of grazing winter annual forages on penetrometer resistance and subsequent grain crop yields in 2005.^a