HARVESTING WINTER FORAGES TO EXTRACT SOIL NUTRIENTS

Authors: Rowe, Dennis; Fairbrother, Timothy

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/3/2003
Publication Date: 9/1/2003
Citation: ROWE, D.E., FAIRBROTHER, T.E. HARVESTING WINTER FORAGES TO EXTRACT MANURE SOIL NUTRIENTS. AGRONOMY JOURNAL. 2003. V.95.P.1209-1212.

Interpretive Summary: Nutrients from manures can accumulate in the soil to a level that they have the potential to escape and pollute the surface waters or even to ground water. The impacts are several, but the most obvious is the overgrowth of ponds with algae due to excess phosphorus in the water. One obvious solution is to control the nutrient concentrations in the soil and to prevent erosion of nutrient containing soil. Winter cover crops in the South protect the soil from erosion. This research indicates that if the winter cover crop is harvested as a hay it can be an important tool in the control of pollution. The choice of which plant species to use as a cover crop and the harvest date is important. A winter clover known as berseem clover proved to be more effective at removing potentially polluting nutrients and heavy metals. The clover removed up to 70% more of some soil nutrients than the grass which is commonly used as a cover crop. Clover as a cover crop gives the farmer an economical way of further controlling the potential for nutrient pollution.

Technical Abstract: Hay harvests can extract from soil the manure nutrients which could cause pollution of surface water or aquifer. This study was conducted to determine hay yields and quantities of nutrients extracted with three winter forages used as cover crops with five cutting dates. Dormant bermudagrass [Cynodon dactylon (L.) Pers.] sod regularly fertilized effluent was fall seeded with `Kendland' red clover (Trifolium pratense L.), `Bigbee' berseem clover (T. Alexandrinum L.), or `Marshall' annual ryegrass (Lolium multiflorum Lam.). Hay was harvested for three springs on five systems: April 1 and June 1, April 15 and June 1, May 1 and June 1, May 15 and June 1, and only June 1 (hereafter named by the first harvest day). The hay yields and yields of N, P, K, Mg, Mn, Ca, Fe, Zn, and Cu were determined on h-1. The three forages averaged nearly identical hay yields. The ryegrass was little affected by harvest date, but May 1 and April 1 were usually the best harvests for red and berseem clovers, respectively. Using two harvests on the legumes increased yields by up to 30% over the single June harvest. The legumes yielded up to 64% more N, 24% more P, and 40 and 72% more of the heavy metals Zn and Cu. The April 1 harvest of berseem clover removed over 30.2 kg h-1y-1 of soil P.