EFFECTS OF INTENSIVE POTATO PRODUCTION ON SOIL QUALITY AND YIELD AT A BENCHMARK SITE IN NEW-BRUNSWICK

The cumulative extent of soil redistribution by erosion and tillage was measured by comparing the Cs-137 content of a soil under intensive potato production with that of an undisturbed forest soil. Soil redistribution rates estimated from Cs-137 contents for the cultivated site varied from a loss of as high as 19.0 kg m-2 year-1 (190 t ha-1 year-1) to a gain of as much as 4.3 kg m-2 year-1 (43 t ha-1 year-1), with an average of 5.3 kg m-2 year-1 (53 t ha-1 year-1) soil loss. Measured soit Cs-137 content and calculated soil loss (and deposition) were both found to be correlated with total potato yield (P<0.01), and with tuber specific gravity (P<0.05), in the two years of yield measurements (1991 and 1992). These years had near normal growing season precipitation, but contrasting distribution patterns of precipitation during the growing season. Estimated soil loss and gain were also correlated (P<0.01) with soil organic carbon and soil phosphorus contents. It is concluded that soil redistribution within the site, caused by either water erosion or tillage, or a combination of both these processes, had a marked effect on soil productivity.