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Impact of Soil Amendments on Reducing Phosphorus Losses from Runoff in Sod

Torbert, H. A., King, K. W., Harmel, R. D.
Journal of environmental quality 2005 v.34 no.4 pp. 1415
pollution control, soil amendments, calcium carbonate, gypsum, ferrous sulfate, dairy cattle, cattle manure, composted manure, phosphorus, losses from soil, agricultural runoff, Cynodon dactylon, turf grasses, pastures, filter strips
Research was initiated to study the interaction between soil amendments (lime, gypsum, and ferrous sulfate) and dissolved molybdate reactive phosphorus [RP ] losses from manure applications from concentrated runoff flow through a sod surface. Four run-over boxes (2.2-m surface area) were prepared for each treatment with a bermudagrass [ (L.) Pers.] sod surface (using sod blocks) and composted dairy manure was surface-applied at rates of 0, 4.5, 9, or 13.5 Mg ha The three soil amendments were then applied to the boxes. Two 30-min runoff events were conducted and runoff water was collected at 10-min intervals and analyzed for RP Results indicated that the addition of ferrous sulfate was very effective at reducing the level of RP in runoff water, reducing RP from 1.3 mg L for the highest compost rate with no amendment to 0.2 mg L for the ferrous sulfate in the first 10 min of runoff. Lime and gypsum showed a small impact on reducing RP , with a reduction in the first 10 min to 0.9 and 0.8 mg L, respectively. The ferrous sulfate reduced the RP in the tank at the end of the first runoff event by 66.3% compared with no amendment. In the second runoff event, the ferrous sulfate was very effective at reducing RP in runoff, with no significant differences in RP with application of 13.5 Mg ha compost compared with no manure application. The results indicate that the addition of ferrous sulfate may greatly reduce RP losses in runoff and has considerable potential to be used on pasture, turfgrass, and filter strips to reduce the initial RP losses from manure application to the environment.