Soil and nutrient removals by erosion and windrowing at a southeastern U.S. Piedmont site

Soil losses from various loblolly pine ( Pinus taeda) harvest and regeneration practices were investigated at a moderately sloping Piedmont site. Treatments were stem-only vs. whole-tree harvest, chop and burn vs. shear pile and disk site preparation, and the repeated application of herbicide vs. none. Harvest method had no effect on erosion rates over the year measured. Erosion on the chop and burn plots (excluding skid trials) was negligible. Erosion on the disked plots over the same year without and with herbicide was 4 and 10 Mg/ha respectively, representing 5 and 10 kg/ha of total N and 1.3 and 2.5 kg/ha of total P. The measured erosion rates agreed well with Universal Soil Loss Equation estimates. Soil losses due to windrowing were unaffected by harvest method and equalled 178 tons of mineral soil per hectare of prepared area. N and P in windrow soil and slash equalled 254 and 61 kg/ha of prepared area, respectively, after burning. These represent a systematic underestimate of nutrient losses during windrowing. Nonetheless, they are greater than losses in whole-tree harvesting, and they exceed natural inputs expected during a rotation. Losses of this magnitude raise the likelihood of reduced long-term site productivity.