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ARS Home » Southeast Area » Tifton, Georgia » Southeast Watershed Research » Research » Publications at this Location » Publication #128739
Title: NUTRIENT UPTAKE AND GROWTH RESPONSE OF GRASS IN BUFFER SYSTEMS RECEIVING SWINE LAGOON EFFLUENT

Author
item Hubbard, Robert
item NEWTON, G - UNIVERSITY OF GEORGIA

Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/1/2003
Publication Date: 11/1/2003
Citation: Hubbard, R.K., Newton, G.L. 2003. Nutrient uptake and growth response of grass in buffer systems receiving swine lagoon effluent. Journal of Soil and Water Conservation. 58(5):232-242.

Interpretive Summary: Management of agricultural effluents is best accomplished by systems that utilize the nutrients contained in these materials. Studies have shown that grass-forest buffer systems are effective in filtering nutrients entering from upslope agricultural systems. Nutrient removal mechanisms involved include uptake by vegetation and degradation by microbial processes. Less is known about using grass-forest systems for utilizing nutrients contained within animal wastewaters, or the relative roles of grass, forest, or other processes in the assimilation of nutrients. A three-year study was conducted to evaluate the use of grass-forest buffer systems for assimilation of nutrients contained within swine lagoon wastewater. As part of the study grass clippings were made at periodic intervals from three positions withing the grass portion of the buffer systems in order to determine the amount of nutrients removed by the grass. .It was determined that buffers of Coastal Bermudagrass (Cynondon dactylon L.) (Tifton 78) 30 m in length removed 44% of the N, 20 % of the P, and 23% of the K when the wastewater was applied at the rate of 800 kilograms N per hectare per year, 215 kilograms P per hectare per year, and 1030 kilgrams K per hectare per year. Overall the study showed that while the grass was assimilating a portion of the nutrients from the wastewater, other chemical and biological components of the system must have accounted for greater retention/assimilation as evidenced by water quality. Results indicate that buffers of grass alone will be less successful in protecting water quality than combined grass-forest buffers. This research was designed to aid land managers in developing systems for managing agricultural effluents so that soils and waters are not degraded.

Technical Abstract: A study was conducted to determine the nutrient uptake and growth response of the grass portions of grass forest buffer systems receiving swine lagoon wastewater. Cuttings were made at three different positions within buffers of coastal bermudagrass (Cynondon dactylon L.) (Tifton 78) over a three- year period. Wastewater was applied at two different rates, 1X or 2X. On average the 1X plots received 800 kilograms N per hectare per year, 215 kilograms P per hectare per year, and 1030 kilograms K per hectare per year, while the 2X plots received twice that amount. Results indicated that grass buffers 30 m in length on average could remove up to 44 % of the N, 20 % of the P, and 23 % of the K when wastewater approximates the 1X rate. Uptake expressed as a percentage would drop by a factor of 1.6 or more when wastewater is applied at a higher rate. Overall the study showed that while grass accounts for a portion of the nutrient removal in grass- forest buffer systems, other factors (denitrification, forest uptake, adsorption) must play a larger role in the nutrient assimilation and filtering commonly associated with grass-forest buffer systems.