|OSTERHOLZ, WILLIAM - University Of Wisconsin|
|RENZ, MARK - University Of Wisconsin|
Submitted to: Soil and Water Conservation Society
Publication Type: Abstract Only
Publication Acceptance Date: 2/22/2017
Publication Date: N/A
Technical Abstract: Alfalfa and corn silage are widely planted for dairy forage production systems throughout the northern regions of the USA, accounting for about 0.8 and 1.9 million hectares per year, respectively. Much of this area could benefit from strategies to reduce soil erosion and nutrient losses. Because these crops are frequently grown in rotation, alfalfa could be interseeded at corn planting to serve as a dual-purpose crop for providing groundcover during silage corn production and forage during subsequent growing seasons. However, frequent stand failure of the interseeded alfalfa due to competition from the corn has been a major obstacle to implementing this system. Recent studies from Wisconsin demonstrated that properly timed foliar application of the plant growth regulator, prohexadione-calcium (PHD), to select alfalfa varieties can improve the survival of alfalfa interseeded into silage corn by up to 300%. When successfully established, interseeded alfalfa produced 200% greater forage yields in its first production year compared to conventionally spring-seeded alfalfa. Preliminary estimates of interseeded alfalfa success rates, corn and alfalfa yields, and PHD application costs suggest that the interseeded alfalfa system could improve net returns of producers by about 30% ($26 per acre per year) compared to a conventional system of silage corn followed by spring-seeded alfalfa. Other studies suggested significant improvements in soil and water conservation: interseeded alfalfa reduced runoff of nitrogen by 35%, phosphorus by 40%, and soil erosion by 62%, and also reduced concentrations of nitrate susceptible to leaching losses in silage corn compared to the conventional system. While additional work is needed to refine the interseeded alfalfa system, the observed improvements in crop yields and soil and water conservation are powerful incentives to continue development of reliable silage corn-interseeded alfalfa production systems for use on farms in the northern USA.