|Fortuna, Ann Marie|
Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/19/2004
Publication Date: 2/1/2005
Citation: Fortuna, A., Rieke, P.E., Jacobs, L.W., Leinauer, B., Karcher, D.E. 2005. Kentucky bluegrass response to use of aquatic plants as a soil amendment. Hortscience.
Interpretive Summary: Rapid aquatic plant growth has limited recreational use of a number of Michigan's smaller lakes. Plant material removed from lakes has posed a new waste disposal problem for municipalities. Using lake weed refuse on area sod farms as a mulch to prevent evaporation of soil water and as fertilizer was viewed as a way to dispose of unwanted trash and provide benefit to local producers. The objectives of this study were to: (i) measure the fertilizer equivalency of lake weed refuse, (ii) establish whether the aquatic plants contained toxic materials, (iii) observe changes in soil water due to the lake weed mulch, and (iv) measure changes in sod growth and quality caused by application of lake weed refuse. The metal content of the lake weeds was low and the nutrient content high. Soil moisture was higher where lake weed refuse prevented evaporation of soil water. The added soil moisture and nutrients provided by the lake weed materials improved sod growth. Earlier rapid growth of turfgrass sod allowed the turf to out compete weeds. The nitrogen supplied by lake weed refuse was greater than the amount of nitrogen required by the turfgrass. Therefore, growers should base the amount of lake weed they apply on the quantity of nitrogen provided by lake weeds and the nitrogen needs of the crop grown. This will prevent excess nitrogen from entering groundwater. Lake weed refuse contained unwanted trash that required removal and could discourage its use by growers. Application of lake weed refuse could ease waste disposal problems, reduce fertilizer inputs for growers and improve the moisture status of sands. Estimates of the fertilizer value of lake weed refuse could be used by state extension agents and local environmental regulators to develop guidelines for the safe and proper utilization of similar waste materials.
Technical Abstract: Rapid aquatic plant growth in Michigan's smaller lakes has reduced their navigability and recreational use. Harvested aquatic weeds have posed a new waste disposal issue for municipalities. Application of lake weeds as a soil amendment on area farms was viewed as a possible waste management option that might benefit local sod producers. The objectives of this study were to: (i) estimate the amount of plant-available N (PAN) released from lake weed refuse, (ii) determine the chemical composition of aquatic plant tissues and their effect on plant-available moisture, and (iii) study turfgrass response to lake weed applications using the criteria of turfgrass quality, growth, and N uptake. The metal content of the lake weeds was low and the nutrient content high. One Mg of lake weeds contained 0.37 kg of phosphorus (P) and 2.5 kg of potassium (K). Estimates of the N supplied by lake weeds (570, 960, and 1200 kg PAN ha-1) were based on data from two 47 d carbon (C) and nitrogen (N) incubations. Application of lake weeds significantly increased plant-available soil moisture, and enhanced sod establishment and turf density resulting in decreased weed pressure. Excess N was present at higher application rates. Therefore, management concerns during the application of lake weeds should focus on nutrient loading and the timing of plant-available N release. Lake weed refuse contained unwanted trash that could discourage its use by growers. Land application of lake weed refuse could ease waste disposal problems, reduce fertilizer inputs for sod growers and improve the moisture status of sands. Further, this information can be of value to environmental regulatory agencies in determining safe and proper utilization of such waste materials.