Transport of Sediment Nitrogen and Phosphorus in Runoff through Cornstalk Residue Strips1
- E. E. Alberts,
- W. H. Neibling and
- W. C. Moldenhauer2
A rainfall simulator study was conducted on a Sidell silt loam (Typic Arguidolls, fine-silty, mixed, mesic) in northwest-central Indiana to evaluate the effectiveness of different lengths and percentage covers of cornstalk residue strips in reducing total nitrogen and available phosphorus discharges associated with the sediment. A 2.7-m long residue strip with 50% surface cover reduced nutrient discharges by about 70% when the nutrient loads entering and leaving the residue strip were compared. Reductions in sediment and nutrient discharges with increasing length and percentage cover of the residue strips were almost proportional.
The sediment was separated by sieving and gravity sedimentation into 10 size fractions ranging from > 2 to <0.002 mm in diam. About 50% of the sediment entering the residue strips was composed of particles >0.05 mm. The 2.7-m long residue strip with 50% surface cover filtered out most of the particles >0.05 mm. As a result, 85% of the sediment leaving this residue strip was in the <0.035-mm size fractions.
Nutrient concentrations of the fractions >0.21 mm entering the residue strips were higher than those concentrations of the 0.05- to 0.01-mm fractions entering the strips. Nutrient concentrations of the fractions <0.21 mm and >0.01 mm increased as the sediment moved through the residue strips, with the effect being related to residue length and percentage cover. Residue reduced the transport capacity of runoff below its sediment load, which caused the denser particies within these size fractions to be deposited. The less dense particles that were not deposited were composed of a greater proportion of small silt and clay primary particles, which increased the nutrient concentrations.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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