Seasonal Growth and Uptake of Nutrients by Orchardgrass Irrigated with Wastewater

摘要

A 2-year field study determined the seasonal growth nutrient accumulation of a forage grass receiving 7.5 cm/wk of primary treated domestic wastewater. The average N and P concentrations in the wastewater were 31.5 and 6.1 mg/L respectively. An established sward of Pennlate orchardgrass (Dactylis glomerata L.) was managed on an annual three cutting system. Grass samples were periodically taken to determine plant dry matter accumulation and uptake of N, P and K. Changes in nutrient uptake within a harvest period were related to both changes in dry matter accumulation and plant nutrient concentration. For maximum yields and nutrient removal, it is recommended that orchardgrass be initially harvested at the early heading stage of growth in the spring. Subsequent harvests should be performed at 5-to6-week intervals. Average daily dry matter, N and P accumulation was greatest during the first harvest period (May in Hanover, N.H.). This would be the most appropriate time to increase the application rate, thus treating excess wastewater stored during the winter. Estimates of monthly plant removal for N and P are presented as a guide in designing land treatment systems according to the procedures given in the EPA/Corps Land Treatment Design Manual. (Author)