SOIL REDISTRIBUTION ON THREE CULTIVATED NEW BRUNSWICK HILLSLOPES CALCULATED FROM 137Cs MEASUREMENTS, SOLUM DATA AND THE USLE

Abstract

¹³⁷Cs, solum data and the USLE were used to estimate soil erosion on three medium-textured soils in New Brunswick that had been in nearly continuous potato monoculture over the past 15 yr. Sampling transects were located on slopes ranging from 425 to 1040 m long, and from 4.8 to 6.0% slope. Ten equally spaced sites were sampled on each transect. The ¹³⁷Cs data were used to divide the sampling sites into four groups: deposition, little erosion or deposition, moderately eroded and severely eroded areas. The four groups generally agreed well with soil profile properties. Solum, A horizon thickness and organic carbon content of the A horizon all decreased going from depositional sites to sites with severe erosion. Variations in A horizon thickness and organic carbon content explained about 65% of the variation in ¹³⁷Cs. Soil losses predicted by the USLE were better correlated with soil losses calculated from ¹³⁷Cs when the ¹³⁷Cs data were used to delineate slope segments that were subject to erosion than when ¹³⁷Cs and USLE soil losses were calculated on a field basis. The USLE overestimated soil losses at high erosion rates. Key words: Erosion, deposition, ¹³⁷Cs, USLE, soil profile