Economic and environmental implications of soybean production and use on Pennsylvania dairy farms

Soybean (Glycine max L.) production is rapidly increasing on Pennsylvania dairy farms. A whole-farm analysis was conducted to determine the potential long-term economic benefit to producers and the environmental impact of growing and feeding soybean as a protein feed supplement. Representative dairy farms were simulated with various production strategies for 25 yr of Pennsylvania weather using the Dairy Forage System Model (DAFOSYM). Production of soybean as a cash crop increased annual farm net return by up to $55 cow^-1 when ample cropland was available to produce most of the feed requirement of the herd. With a more restricted land base, there was less economic benefit to shifting land from corn (Zea mays L.) or alfalfa (Medicago sativa L.) production to soybean. When the soybean was fed in a raw or roasted form, most of this economic benefit was offset, giving an increase in annual net return of <$15 cow^-1. There was also little environmental benefit (reduced N loss or soil P accumulation) in growing soybean as a cash crop or feed on dairy farms. In general, the current trend toward producing and feeding soybean on Pennsylvania dairy farms does not appear to provide substantial long-term economic benefit to the producer, nor does it appear to reduce the potential impact of the farm on its environment. However, under specific farming practices such as inefficient feeding of protein supplements or the production and feeding of high corn silage rations, an economic benefit of up to $100 cow^-1 can be obtained through soybean production and feeding.