Animal manures are a valuable source of plant nutrients in crop production in western Canada. Significant yield responses to nutrients added as swine manure and cattle manure have been reported in field trials in Saskatchewan. Increased availability of nitrogen in manured soils is the primary factor associated with reported yield and protein increases in these studies, particularly with liquid swine manure. In some instances, part of the yield response to manure addition may be attributed to the enhanced availablility of othernutrients such as phosphorus when soil availability of those nutrients is limiting. Thereofre manure addition can make a signifiant contribution to crop nutrition by increasing the availability of many nutrients in the soil. However, the amounts, forms, availability and therefore the balance of available nutrients in the soil following manure addition is controlled to a large extent by the compostion of the manure. This compostion is variable depending on factors such as the animal physiology, feed rations/additives, manure handling and storage as well as environmental conditiions which effect nutrient retention. As such, when manure is applied, nutrients are applied in proportion or balance thy are present in the manure source, hcih amy be different than the relative proprtions required by the crop to be grown.