Influence of long-term application of N and S fertilizers (1980-2002) and liming in 1992 on dry matter yield of grass and soil properties in a Dark Gray Chernozem in north-central Saskatchewan
Most soils are deficient in plant-available N in the Prairie Provinces of Canada, and in the Parkland region, many soils are also insufficient in available S for high crop yields. Long-term field experiments, initiated in 1980 and 1996 on a Dark Gray Chernozem loam soil at Canwood in north-central Saskatchewan, were conducted to determine the effects of N, S and lime application and forage removal on forage dry matter yield (DMY) and soil properties. The results indicated that application of N or S alone had only a little effect on DMY, while application of N together with S substantially increased DMY. Decline of soil pH by annual applications of N and S fertilizers mainly happened in the 0-5 cm layer. In layers below 10 cm, soil pH tended to increase with N or NS fertilization. Surface application of granular lime increased soil pH mainly in the 0-5 cm layer, and the high pH was maintained for at least 9 years. The TOC and TN mass in the 0-7.5 cm soil layer increased with annual applications of N and S fertilizers, and the increase was more pronounced with application of N and S together. In the subsoil layers, the N treatment tended to decrease, but the NS treatment tended to increase the TOC and TN. This suggests that application of N and S together was more effective in increasing C and N sequestration in a soil deficient in both N and S.
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