Grazing impacts on selected soil parameters under short-term forage sequences

Long-term cultivation is known to change soil physical and chemical propert ies, but little is known about whether short-term agricultural practices, s uch as rotational grazing, can initiate such changes. This study investigat ed the impacts of 3 grazing intensities (heavy, medium, and light) and 4 fo rages on selected soil physical and chemical parameters of a Typic Haplusto ll at Lacombe, Alberta. Measurements were conducted on soil samples collect ed at the beginning (1993) and the end (1996) of the study. Two perennial f orages, smooth bromegrass (Bromus inermis cv. 'Carlton') and meadow bromegr ass (Bromus riparius cv. 'Paddock'), and 2 annuals, a mixture of triticale (X Triticosecale Wittmack cv. 'Pika') and barley (Hordeum vulgare L. cv. LA C Lacombe') and triticale alone were used for the study. Grazing intensity or forage species did not affect carbon-to-nitrogen ratio. Grazing intensit y influenced changes in available water holding capacity for the 0-5 cm int erval, soil nitrogen for the 30-45 cm interval, soil pH for the 5-15 cm int erval and electrical conductivity for all depth intervals except for the 0- 5 cm interval (P less than or equal to 0.05). Forage species affected chang es in soil carbon in the 0-5 cm interval, soil pH between 0 and 15 cm, and electrical conductivity between 5 and 45 cm (P less than or equal to 0.05). Soil electrical conductivities for all grazing levels and forage treatment s were within the range (i.e. 0-2 dS m(-1)) considered to have negligible e ffects on plant growth. The minimal effects of grazing and plant species on soil parameters in this study may have been due to the resilient intrinsic properties of the sail and/or the short study length.