ABSTRACTat the slower rate of freezinl.

Field experiments were conducted at Guelph, Ontario, to determine the effects of applying as much as 376 metric tons/ha of raw, nonsegregated, shredded solid waste plus 4.6 cm of anaerobically digested sewage sludge on soil physical properties, soil nitrogen and carbon, and the yield of corn grain (Zea mays L.).Shredded waste and sewage sludge were applied to plots in July 1971 and again in August 1973. Corn was grown in 1972, 1974, 1975, and 1976 with chemical fertilizer being applied the last 2 years. Physical determinations were made on soil samples collected prior to corn planting in 1976.Soil C and N and water‐stable aggregation increased, while bulk density decreased with increments of solid waste added. Soil moisture, expressed volumetrically (cm3/cm3) and retained at pressures of 0.04, 0.33, and 15 bars and available water, was not significantly affected by waste additions. No consistent relationship appeared to exist between kinds and amounts of wastes added and corn grain yields for four harvestings.

The movement and survival of Pratylenchus penetrans were studied in three soils, Fox loamy sand, Jeddo loam, and Vineland silt loam that had marked differences in particle-size distribution, moisture retention, aeration, and pore size. Nematodes on paper disks were placed on the surface of soil cores that had been packed to two bulk densities and equilibrated at eight moisture regimes. After seven days the cores were partitioned, the nematodes extracted and counted. At low bulk density, a percentage of 4th and adult stages moved 4 cm in Fox between 10 and 3000 cm H2Ο moisture tension and in Jeddo and Vineland between 30 and 300 H2Ο; a percentage of 2nd and 3rd stages moved 4 cm in Fox between 10 and 100 cm H2Ο moisture tension and in Jeddo and Vineland at 30 and 100 cm H2Ο. However all stages moved only an average of 2.0 cm in Fox at 10 cm H2Ο moisture tension and in Jeddo and Vineland at 100 cm H2Ο. At high bulk density, a smaller percentage of all stages moved 4 cm only in Fox at 30 and 100 cm H2Ο moisture tension and in Jeddo at 100 cm H2Ο. Moreover 4th and adult stages moved only an average of 1.0 cm in Fox, 1.3 cm in Jeddo and 0.5 cm in Vineland at 100 cm H2Ο moisture tension in each soil; 2nd and 3rd stages moved an average of 1.0 cm in Fox and 0.5 cm in Jeddo at 100 cm H2Ο in both soils. In Vineland 2nd and 3rd stages did not move. Eight to 12 percent of the soil volume was occupied by air when movement of all stages peaked in each soil. It is suggested that the relatively large sand grains in the Fox soil provided pore sizes and moisture characteristics more suitable for nematode movement.

A laboratory study was carried out to determine the breakdown of soil structure by alternate freezing and thawing. Surface samples of Haldimand clay from plots cropped with corn for the 3 previous years and from plots of continuous blue grass sod were used.Cycles of freezing and thawing caused a significant breakdown of aggregates from the sod plots at all moisture levels employed except the one equivalent to 1.0 atmosphere pressure. The destructive effects of alternate freezing and thawing increased with increasing moisture in the well-aggregated soil (blue grass), but the effects on a poorly aggregated soil (corn) were not significant.

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