Illinois Fertilizer
Conference Proceedings
January 28-30, 1991
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Don Bullock, Tom Bicki and Richard Farnsworth1
Due to the nature and the culture practices of hairy vetch (Vicia villosa Roth.) and rye (Secale cereale), this project was not initiated until October 1990. All cover crops at all locations were planted in a timely fashion and established. A brief review of the proposal will be presented.
Environmental and economic concerns have fueled interest in agriculture's economic competitiveness, soil erosion, N fertilizer efficiency, and nitrate leaching (Heichel and Barnes, 1984). We believe that these concerns will result in legislation, at both the federal and state levels, regulating N fertilizer and tillage use for summer feed grain crops in Illinois.
Winter cover crops will be probably required in this legislation. The cover crop will be either a legume, which produces significant amounts of organic nitrogen via nitrogen fixation, or a small grain which scavenges residual soil nitrates for the production of organic nitrogen, and consequently, reduces the amount of nitrates available for over-winter leaching.
Many winter cover crops can be used to reduce soil erosion and provide organic N. In the lower CornBelt, hairy vetch is the preferred legume while rye is the preferred nonlegume (Ebelhar et al. 1984, Frye et al. 1988). Most research indicates that hairy vetch contributes an equivalent of 60 to 90 pounds N per acre, but resulting yields are not usually economically competitive with corn receiving the normal 125 to 250 pounds fertilizer N per acre (Moschler et al. 1967, Mitchell and Teel 1977, Ebelhar et al. 1984). The reason for the yield reduction is explained as a combination of the large N demand of corn, the necessity of early corn planting dates, and the tendency of hairy vetch to deplete soil moisture.
This previous research suggests that new legislation mandating cover crop use in order to reduce soil would have to allow supplemental fertilizer N use if Illinois corn farmers are to remain economically competitive.
Contrary to the published literature, many Illinois farmers utilizing cover crops report that hairy vetch can, under the right conditions, produce in excess of 300 lb of N per acre (Holsapple, 1990). The difference may be an artifact of improperly managed cover crops in the published literature. This proposed research will help to resolve some of these questions
Rye has been shown to be inferior generally to hairy vetch in the lower CornBelt (Ebelhar et al. 1984), but environmental conditions and corn planting date requirements often result in vetch not establishing well and/or not producing a substantial biomass. We speculate that under such conditions rye, which is easier to establish and has greater early season growth, may prove to be comparable to hairy vetch for the purposes described above.
Corn is the major feed grain crop in Illinois and virtually all of the winter cover crop/summer feed grain crop rotation work in this area has looked only at corn, but corn is probably not the best feed grain crop for such a system. Grain sorghum (Sorghum bicolor L.) has a shorter grain-fill period and thus can be planted later than corn without suffering a yield reduction (Olson et al. 1986). Grain sorghum also has a lower N requirement for optimum economic production than corn (80 pounds per acre vs 160 pounds per acre) (Olson et al. 1986), and thus it may be a potential alternative summer feed grain. It looks especially promising on drought-prone soil or if it is found that vetch must be allowed to grow relatively late into the spring in order to fix more organic N.
Wagger (1987) reported that killing hairy vetch the first week of May instead of the third week of April resulted in an additional production of 1.78 tons dry matter per acre and 52 lbs N per acre. This is in agreement with Frye et al (1988) who noted that the majority of the vegetative growth of hairy vetch occurred in the three weeks prior to the onset of the reproductive stage.
The later planting date would result in more subsoil moisture depletion by the cover crop, but utilization of grain sorghum instead of corn would allow for a later planting date and thus permit a producer to wait longer for adequate soil moisture in the planting zone after the cover crop has been destroyed. Grain sorghum is also more drought-tolerant than corn (Olson et al. 1986). Hargrove (1986) has demonstrated in Georgia that a production system using winter legumes followed by grain sorghum is possible. Such a system has not been investigated in the central CornBelt and farmers and scientists have little experience to predict the outcome of such a system.
The objective of this study will be to examine the production efficiency, nitrogen requirement, environmental consequences, and economic competitiveness of cover crop production systems for ,a summer feed grain/soybean rotation.
This field experiment will be conducted at Albion, Greenup, and Fisher, Illinois. All. locations will be cooperating production farms. It will be a split-split-split-splitsplit plot in a randomized complete block design with three replications per location. Whole plot treatments will be tillage used the spring prior to feed grain planting: 1) no-till and 2) plow + disk. The split-split treatments will be a type of cover: 1) hairy vetch, 2) rye, and 3) conventional i.e. no planted cover. The split-split-split plot treatments will be a feed grain% l) grain sorghum and 2) corn. The split-splitsplit-split plot treatments will be feed grain planting date: 1) May 1, and 2) May 20. The split-split-split-split-split plot treatment will be N fertilizer rate: 1) 0 lb N/ac, 2) 80 lb N/ac, 3) 160 lb N/ac, and 4) 240 lb N/ac. Individual plot size will be approximately 20 feet wide (8, 30 inch rows) by 30 feet long.
Measurements will include soil loss, nitrate leaching, vetch and rye biomass production and mineral content, emergence and survival percentages, feed grain yield, feed grain moisture, and tissue nutrient concentration. An economic analysis of the cropping systems will be performed and will focus on the mean and variability of profits.
Data collection will begin in the spring of 1991. We propose that this project will aid in the identification and development of environmentally-sound and economically competitive cropping systems for Illinois.
Ebelhar, S.A., W.V. Frye, and R.L. Blevins. 1984. Nitrogen from legume cover crops for no-tillage corn. Agron. J. 76:51-55.
Flannery, R.L. 1981. Conventional vs. no-tillage corn silage production. Better Crops 65:3-6 (Summer-Fall).
Frye, V.W., R.L. Blevins, M.S. Smith, S.J. Corak, and J.J. Varco. 1988. Role of annual legume cover crops in efficient use of water and nitrogen. p.. 129-154. In W.L. Hargrove (ed.) Cropping strategies for efficient use of water and nitrogen. ASA.Spec. Publ. 51. ASA, CSSA, and SSSA, Madison, WI.
Hargrove, W.L. 1986. Winter legumes as a nitrogen source for no-till grain sorghum. Agron J. 78:70-74.
Heichel, G.H., and D.R. Barnes. 1984. Opportunities for meeting crop nitrogen needs from symbiotic nitrogen fixation. p.49-59. In D.A. Bezdicek et al. (ed.) Organic farming: Current technology and its role in a sustainable agriculture. Spec. Pub. 46. American Society of Agronomy, Madison, WI.
Holsapple, Terry. 1990. Fertilizer freedom. The New Farm. January. pp. 29-30.
Moschler, W.W., G.M. Shear, D.L. Hallock, R.D. Sears, and G.D. Jones. 1967. Winter cover crops for sod-planted corn: Their selection and management. Agron. J. 59:547551.
Mitchell, W.H., and M.R. Teel. 1977. Winter-annual cover crops for no-tillage corn production. Agron. J. 69:569-573.
Olson, R.A., W.R. Raun, Yang Shou Chun, and J. Skopp. 1986. Nitrogen management and interseeding effects on irrigated corn and sorghum and on soil strength. Agron. J. 78:856-862.
Triplett, G.B. Jr., F. Haghiri, and D.M. Van Dorei, Jr. 1979. Plowing effect on corn yield response to N following alfalfa. Agron J. 71:801-803.
Varco, J.J. 1986. Tillage effects on transformation of legume and fertilizer nitrogen and crop recovery residue nitrogen. Ph.D. dies. Univ. of Kentucky, Lexington (Dies. Abst. 8705310).
Wagger, M.G. 1987. Timing effects of cover crop desiccation on decomposition rates and subsequent nitrogen uptake by corn. p. 35-37. In J.F. Power (ed.) The role of legumes in conservation tillage systems. Soil Conserv. Soc. AM., Ankeny, IA.
