Soil conditions and early crop growth after repeated manure applications
Development of the swine and cattle industries has led to an increase of manure application to agricultural lands in Saskatchewan. Studies have been conducted to determine the nutrient benefits of swine manure application. However, a need was also identified for information on the effects of manure application on soil physical and chemical properties. The objective of this study was to examine the effect of repeated applications of manure on soil physical and chemical properties and to relate those effects to early plant growth and development.Four experimental sites were used, representing the Dark Brown (Plenty), Brown (Riverhurst – irrigated), Black (Dixon) and Gray (Melfort) Soil Zones of Saskatchewan, where liquid swine manure had been applied for four to seven years. At each site, treatments were 1) a control treatment, 2) a nitrogen based agronomic rate of manure application, 3) a high rate of manure application (2-4x the agronomic rate) and 4) a urea fertilizer treatment. At the Dixon site, the same two manure treatments with cattle manure were also examined.Soil strength, as determined by penetration resistance measurements and barley (Hordeum vulgare) emergence were measured at two experimental sites (swine and cattle manure trials at Dixon, SK) in a field study. Penetration resistance was measured at 5, 10, 15 and 20 cm depths, 20, 39 and 123 days after seeding using a recording cone penetrograph. Twenty days after seeding, there were no significant differences among treatments at the 10, 15 and 20 cm depths. But, at the 5 cm depth, the control treatment had soil strength 0.11 MPa lower than the two manure rates. The manure treatments were not significantly different from the urea treatment. Thirty-nine days after seeding, the soil strength of the low rate manure treatment was 1.1 MPa greater than the control at the 10 cm depth, but not significantly different from the urea treatment. One hundred and twenty three days after seeding, the control treatment had greater soil strength than the high rate of manure at 5 and 10 cm depths by 0.28 and 0.71 MPa respectively. At the 20 cm depth, the high rate of manure had the greatest soil strength. Barley emergence on the two manured treatments did not differ significantly from the control. Aggregate size was measured in field samples collected from all sites. Aggregate size for the manured treatments did not differ from the control at any site.Soil crust strength, flax emergence, infiltration rate, salinity, sodicity, coefficient of linear extensibility (COLE) and modulus of rupture were measured under controlled conditions in intact cores of soil removed from all five experimental sites. All soils were treated with a simulated rainfall from a Guelph Rainfall Simulator II. Following the simulated rainfall, crust strength was measured with a hand-held penetrometer. Soil crust strength was measured daily for 10 days as the cores dried. Repeated applications of liquid swine manure at either low or high rates decreased soil strength in the Plenty, Riverhurst and Melfort soils, and increased soil strength in the Dixon soil. Repeated applications of liquid swine manure at low rates caused flax emergence to decrease for the Riverhurst soil compared to its control and had no significant effect at the other sites. There were no notable differences in infiltration rates among treatments. Repeated applications of liquid swine manure caused salinity (EC) to increase slightly for the Plenty and Riverhurst soils, and sodicity (ESP) to increase slightly for the Melfort and Dixon soils relative to their control. The COLE and modulus of rupture measurements indicated no significant effects and were inconclusive due to difficulties in measurement. None of the properties measured in any of the treatments exceeded threshold values for soil productivity, or where plant injury might be considered an issue. It is concluded that repeated (four to seven) annual applications of liquid swine or cattle manure would not cause any large alterations in soil strength, aggregation, infiltration, salinity, or sodicity that would affect early plant growth and development. This was supported by field and lab measurements of emergence that showed limited effect.
soil chemical properties, soil physical properties, swine manure, salinity, sodicity, soil
Master of Science (M.Sc.)