Submitted to: American Forage and Grassland Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 1/20/2001
Publication Date: 4/25/2001
Citation: Rotz, C.A., Soder, K.J., Roth, G.W. 2001. Environmental and economic impacts of a corn and rye double crop system on a pennsylvania dairy farm. American Forage and Grassland Conference Proceedings. 10:166-170. Interpretive Summary: Nitrogen loss to ground water from corn land is a concern on dairy farms in the mid Atlantic region. Animal manure must often be spread on corn land in the fall. When the land remains fallow over the winter and early spring months, moisture from rain and melting snow carries much of this nitrogen in the form of nitrate through the soil and into the ground water under the efarm. Ultimately this nitrate moves to wells, springs, and other water sources where high levels can cause risk to human health. Replacing fallow land with a winter crop such as rye can reduce this loss of nitrogen and the resulting environmental damage. The rye draws the nitrate from the soil where it is used in crop growth, greatly reducing the loss to ground water. The rye crop can be harvested in the spring as a high quality forage for animal feed, or it can be killed and used as mulch where the plant nutrients are returned to the soil to be used in the growth of the following corn crop. The strategy of using the rye as mulch was found to reduce annual nitrate loss by 35 lb of nitrogen per acre of rye, with a small economic loss to the farmer of about $30 per acre. When harvested as feed, similar reductions in nitrate loss were obtained with a small increase in farm profit of $50 per acre. Therefore, to encourage greater use of winter rye as a mulch crop, policymakers should consider having society share the production costs of the crop. When possible, producers should use this crop for animal feed to recoup production costs along with a small increase in farm profit.
Technical Abstract: Double cropping corn after winter rye is becoming a popular option on dairy farms in the mid Atlantic region. The rye crop reduces erosion and it takes up soil nitrate to reduce N leaching loss through the winter and early spring months. When harvested as silage in the spring at an early boot stage of development, the crop provides high quality forage. The crop pcan also be killed with herbicide and used as a mulch and green manure, increasing the yield of the following corn crop. A dairy farm in southern Pennsylvania was simulated with a whole-farm model (DAFOSYM) to evaluate the long-term production, environmental, and economic benefits of these double-cropping strategies. Averaged over 25 years of weather, double cropping corn after rye silage reduced N leaching loss from the whole farm by 25% (8 lb N/acre/yr), increased total feed production by 6%, and increased annual farm profit by $50/acre of rye compared to a corn and alfalfa rotation. Using the rye as mulch provided a similar reduction in leaching loss, increased feed production up to 3%, but reduced farm profit by $32/acre of rye. Therefore, double cropping corn with winter rye provides a good strategy for reducing N leaching losses from dairy farms, and farm profit can be improved when the rye is harvested as silage.