CATTLE MANURE AS A NUTRIENT SOURCE FOR BARLEY AND OILSEED CROPS IN ZERO AND CONVENTIONAL TILLAGE SYSTEMS

Manure application should be equally effective in meeting crop nutrien t requirements in zero and conventional tillage systems in order to be sustainable in a semi-arid region. A study was conducted from 1993 to 1996 at Scott and Melfort, Saskatchewan, to determine if feedlot catt le manure and inorganic N fertilizer were equally effective as nutrien t sources for barley (Hordeum vulgare L.), canola (Brassica rapa L.) a nd flax (Linum usitatissumum L.) production, and soil N dynamics, in z ero and conventional tillage systems. Inorganic fertilizer was compare d with a factorial combination of two manure treatments: manure compos ition (fresh versus stockpiled), and application rate and frequency (a nnual versus once every four years). Barley and oilseed yields at Scot t did not differ between fertilizer and manure treatments, whether man ure was applied annually or once every 4 yr. At Melfort, the site with the highest yield potential, grain yields were 24% lower with manure. This yield reduction could be related to soil N availability; net N m ineralization was 37 kg ha(-1) lower in plots that received manure rat her than inorganic fertilizer. Yield responses to the different types of manure and inorganic fertilizer were similar under zero-till and co nventional tillage management. Low levels of N volatilization from the manure, and similar levels of net N mineralization, explained why cro p responses to nutrient source did not differ with tillage system. Fee dlot cattle manure can be applied as a nutrient source when surface ap plied in a zero-till system without significant yield reductions compa red with soil incorporation in a conventional tillage system.