Can Cover Crops Pull Double Duty: Conservation and Profitable Forage Production?

Data from a recent survey suggests that the major reasons Nebraska crop producers plant cover crops are to improve soil organic matter, reduce erosion, improve soil water holding capacity, produce forage, and improve soil microbial biomass. Fortunately, many of these benefits appear to be positively correlated with production of above-ground biomass. Thus, selecting species that will produce the greatest biomass should be beneficial for both conservation and forage production. Furthermore, the limited data available suggests grazing of cover crops does not have large negative crop production, soil, or environmental impacts. In the north central US the production window following wheat harvest, male row destruction in hybrid seed corn, and to a lesser extent following corn silage harvest is long enough to produce 2,500 to 4,500 kg DM/ha of high-quality, fall forage. In the past 4 years, we have conducted 8 trials using predominantly oats and brassicas planted in mid- to late-August. Forage nutritive value of oats and brassicas is extremely high (70 to 80% IVDMD; 14 to 23% CP in early November) and remains high through December with only a 4 to 7% unit decrease in IVDMD and no change in CP. Thus, it appears that delayed grazing could be an option to maximize potential forage yield. Fall-weaned calves (200 to 290 kg BW) grazing oats with or without brassicas in November and December (48- to 64-days) at stocking rates of 2.5 to 4.0 calves/ha have gained between 0.60 to 1.10 kg/d. The cost of gain has ranged from $0.46 to $2.20/kg when accounting for seed costs plus establishment ($52 to 106/ha), nitrogen plus application ($0 to 72/ha), fencing ($12/ha) and labor ($0.10/calf/d). While soybeans and corn harvested for grain do not provide a large enough growing window to accomplish fall grazing, similar dual purpose cover crop practices are often accomplished by planting winter hardy small cereal grass, such as cereal rye or winter triticale in the fall and grazing in the spring. However, traditional planting dates for corn and soybean result in a 30- to 45-day grazing period prior to corn and a 45- to 60-day period prior to soybean planting. Planting cover crops to provide late fall or early spring grazing has potential. However, incorporating forage production into current cropping systems greatly increases the need for timeliness of management since the window of opportunity for forage production is quite narrow.