Submitted to: American Society of Agronomy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/13/2006
Publication Date: 6/5/2006
Citation: Rowe, D.E., Fairbrother, T.E., Sistani, K.R. 2006. Winter cover crop and management effects on summer and annual nutrient yields. Agronomy Journal. 98:946-950. Interpretive Summary: Swine farmers are in a particularly difficult situation when it comes to managing the waste from animal production. The liquid waste which is commonly stored in artificial lagoons is used to irrigate nearby fields which are usually growing a grass to be used as animal feed. One difficulty is that this farmer can not be polluting the air, water, or land and the second is that the cost of transporting the lagoon water, a very dilute fertilizer, is very costly. Thus the farmer regularly pumps from the lagoon and applies to the same fields time after time. To avoid pollution problems, the farmer must manage his land to minimize the loss of potentially polluting nutrients in the water leaving the field by trying to remove as much of the nutrients as possible in the harvested hay. This research shows that growing berseem clover during the winter followed by proper harvesting increased the nutrient yield in the winter as expected; but, unexpectedly, it also improved the summer yields of the bermudagrass yields from these fields. No winter harvest system always had the best yields of manure nutrients removed in the harvested hay, but the common method used by farmers in the South, a single harvest of the winter cover crop, was the least efficient method for removing polluting minerals. Harvesting the winter cover crop twice in the spring has beneficial effects on both the yield of the winter cover crop and the summer cover crop.
Technical Abstract: Effluent from a swine (Sus scrofa domesticus) lagoon is often applied repeatedly to nearby fields because of logistical and cost constraints. Best management practices are needed to remove manure nutrients from soil and sustain the safe use of the spray field. This study determines the effects of three winter cover crops, ‘Kenland’ red clover (Trifolium paratense L.), ‘Bigbee’ berseem clover (T. alexandrinum L.) and ‘Marshall’ annual ryegrass (Lolium multriflorum Lam.) harvested on five dates on summer yields of bermudagrass hay and N, P, K, Mg, Mn, Ca, Fe, Zn, and Cu. Bermudagrass following berseem cover had the largest yield of hay or mineral. The best harvest date varied for the mineral measured, but the lowest yielding was either a single June 1 harvest or a two-d harvest system of April 1 and June 1. For the annual performance, combining summer and winter production, berseem clover always had the greatest yield and for the environmentally important minerals N, P, Cu, and Zn the best yields were from a two-day harvest of April 15 and June 1 which was not the best yielding harvest for either winter or summer production. Harvesting the winter cover crop in addition to the usual summer hay increased mineral extraction by 60 to 150% over that of the summer harvest. Tests on summer performance and winter performance in isolation were informative and did indicate the best winter cover crop species, berseem clover, but did not indicate the best management system for annual performance.