Orchardgrass Ley for Improved Manure Management in Wisconsin: I. Forage Yield, Environmental Impact, and Production Costs

Abstract

Spreading dairy manure in climatic zones with a short growing season that are dominated by full season crops such as corn (Zea mays L.) and alfalfa (Medicago sativa L.) is a challenge. However, replacing these with a grass ley (GL) does open several windows for manure spreading. The effects of such a strategy were examined in a 3‐yr, 2 by 2 factorial trial comparing orchardgrass (Dactylis glomerata L.) and corn silage (CS) with either manure or fertilizer at two locations in Wisconsin. In the fourth year a test crop of CS was grown following both crops. During the first 3 yr, the manured corn plots out‐produced the manured grass plots (16.0 vs. 8.6 Mg DM ha−1 yr−1) but in the fourth year the corn following the orchardgrass ley system was more productive than when following corn (20.7 vs. 14.9 Mg DM ha−1). Soil test phosphorus (STP) values climbed 2 to 4 mg kg−1 yr−1 and soil test potassium (STK) 14 to 20 mg kg−1 yr−1 under the manured systems. Variable costs per metric ton of forage dry matter (DM) were significantly higher in the manured GL compared to manured continuous CS system ($67 vs. $43 Mg−1). This can be considered a worst case scenario due to the frequent manuring in the ley system. Also, it is difficult to include the managerial and economic advantages of having adequate summer manure spreading locations. Thus, including a GL may be an ecologically and economically sound strategy where summer manure spreading is required.