EFFECTS OF TOPOGRAPHICAL POSITIONS, SOIL TEST VALUES, AND FERTILIZER USE ON YIELDS OF WHEAT IN A COMPLEX OF BLACK CHERNOZEMIC AND GLEYSOLIC SOILS

Abstract

In southeastern Saskatchewan, from 1965 to 1968, wheat was grown in 15 experiments testing N, P, and NP fertilizers on 8–12% topographical slopes on an association of Black Chernozemic and Gleysolic soils developed on moderately rolling calcareous glacial till. All tests were on summer fallow. Without fertilizer, the yield of wheat ranged from 1150 kg/ha on the crown of the knolls to 1930 kg/ha in the depressions. Phosphate fertilizer increased the yield of grain by 20–30% on the crowns, upper slopes, and midslopes (70% of the area) and by less than 10% on the lower slopes and in the depressions. Excluding the depressional areas (10% of the area), the average phosphorus content was 10 ppm in the surface soil. The average NO3-N content of the top 60 cm of soil was 34 ppm. The basic pedological and microclimatological factors of the soil catena affected the yields of wheat more than soil fertility (and fertilizers).