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This article in JEQ

  1. Vol. 10 No. 3, p. 345-349
    Received: Aug 23, 1980



Effects of Dairy Manure on Phosphorus Concentrations and Losses in Tile Effluent1

  1. G. W. Hergert,
  2. S. D. Klausner,
  3. D. R. Bouldin and
  4. P. J. Zwerman2



Dissolved phosphorus concentrations and losses in effluent from a tile-drained silt loam were compared before and after manuring. Effluent samples were collected from 0.33-ha tile-drained plots for 4 years before and 3 years during consecutive annual dairy manure applications of 35 or 200 wet metric tons/ha. Plots had received fertilizer P in years prior to manuring. More than 95% of the effluent samples had dissolved molybdate reactive P (DMRP) concentrations < 30 ppb before manuring. During the 3 years the manure was applied, 53 and 92% of the effluent samples contained < 30 ppb P for the 200- and 35-metric-ton applications, respectively. The flow-weighted DMRP concentrations in tile effluent were 116, 441, and 97 ppb for 200 metric tons of manure/ha per year, and 22, 10, and 9 ppb for 35 tons/ha per year, respectively, during the 3 years manure was applied.

The tile flow accounted for about 40% of the drainage water lost from the plots, but the P contents of tile flow were 10% of total dissolved P losses in surface runoff. P additions from 30 to 40 wet metric tons/ha of manure would be adequate to meet crop needs but should not produce excessively high P concentrations in tile flow.

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