Soil chemical changes following manure application on irrigated alfalfa and rainfed timothy in southern Alberta

In areas within Alberta where suitable cultivated land is not available, or for convenience, the use of forage land is an alternative for manure application. However, there is limited research on the effects of manure on forage land in the province. The objective of this 5-yr study was to determine the effects of manure on soil chemical properties of forage land. Cattle (Bos taurus L.) and hog (Sus scrofa L.) manures were applied at five rates on irrigated alfalfa ( Medicago sativa L.) and on rainfed timothy(Phleum pratense L.) sites. Treatments were replicated four times and arranged in a randomized complete block design. Soil samples (0 to 15, 15 to 30, 30 to 60, 60 to 90, 90 to 120, and 120 to 150 cm) were collected each spring prior to manure application. Manure application on forage land significantly affected soil chemical properties such as increases in NO3-N, PO4-P, K, Na, and electrical conductivity. There was also evidence of accumulation and some downward movement of NO3-N, Na, and K below 15 cm. The higher manure application rates used in this study (>31 Mg ha-1 cattle manure and >42 Mg ha-1 hog manure; wet weight) are not sustainable in terms of potential environmental risk, such as leaching of NO3-N to groundwater, loss of P in runoff water, and increased soil salinity. Appropriate application rates should be based on crop nutrient requirements and management practices that include regular manure and soil testing. Key words: Alfalfa, timothy, manure, hog, cattle, soil nutrients, electrical conductivity