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Fallow plots were maintained at four sites that varied with respect to soil type and slope aspect and gradient to determine seasonal patterns of soil loss in southwestern Quebec. Equipment used to measure and record runoff included tipping-bucket flowmeters and Datapod digital recorders. Soil loss was measured on a seasonal basis from September 1983 to August 1985, to compare the percentage of annual soil loss by water that occurred during winter and summer months. Summer soil loss accounted for approximately 80% of the total annual soil loss from coarse-textured sites. Winter soil losses at the fine-textured site were responsible for almost 90% of the annual soil loss from that site. Key words: Soil erosion, universal soil loss equation, spring runoff

Increasing areas available for corn (Zea mays L.) production in eastern Canada have stimulated the search for improved management practices to obtain higher yields. These management practices include hybrid selection, plant density, and fertility optimization. Large year‐to‐year variations in corn yields due to weather, however may mask management effects. The objective of this study was to quantify corn grain yield, stover yield, and total dry‐matter production as functions of heat units (HU) and total seasonal water inputs. A field experiment was conducted on a Brookston sandy clay loam soil (fine‐loamy, frigid, mesic Typic Hapludalf) in Quebec from 1984 to 1989. Empirical equations for corn grain, stover, and total drymatter yield were developed for combinations of two plant populations (65 000 and 90 000 plants ha−1) and two fertilizer rates (170‐44‐141 and 400‐132‐332 kg ha−1 as N‐P‐K). Corn grain yield was a function of HU under conventional management practices with low and high HU reducing yields. Corn grain yield with the higher plant population and the higher fertilizer rate was proportional to the product of HU and water inputs received during the growing season. Interactions between management practices indicated that management practices must be devised for most probable climatic conditions. Optimization of climatic factors and management practices could increase grain corn yield.

Silage corn (Zea mays L.) is a major crop in eastern Canada, and yield increases due to added N and K have been noted. However, possible interaction between N and K, and the effect of weather conditions on yield response and maturity must be determined for rational use of N and K fertilizers. A fertilizer experiment on the production of silage corn using urea and KCI was established on an Ormstown silty clay loam (fine silty, mixed, non‐acid, mesic Typic Humaquept) for 4 yr. Rates of fertilizer were 0, 90, and 180 kg N ha−1, and 0, 60, and 120 kg K2O in the first 2 yr, increased to 0, 120, and 240 kg K2O ha−1 in the last 2 yr. Yields of silage corn were increased with N in 3 yr and with K in 2 of the 4 yr. An interaction between N and K was found in the years when there were yield responses to added KCl, indicating that increased crop yields with K occurred only at relatively high N rates. Added N increased dry matter contents of corn plants, whereas added K reduced dry matter contents at low rates of N. Relative yields of the control plots over the high N–K plots were correlated positively with precipitation during the growing season. Added urea when combined with added KCl increased exchangeable and soluble K, probably due to reduced K fixation by illite, mica and vermiculite minerals in the soil.