Performance of wild oat (Avena fatua L.), wheat and flax in direct-seeding systems in relation to monoammonium phasphate and potassium chloride rate and placement

Abstract

To determine the impact of monoammonium phosphate (MAP) and potassium chloride (KCl) fertilizer placement on wild oats in direct-seeded spring wheat and flax, 4 field experiments were conducted on 2 soil types in 1997 and 1998. Growth chamber experiments were conducted to compare the growth response and uptake potential of each species for phosphorus (P) and potassium (K). Growing seasons varied, with 1997 being dry and 1998 wet; however, general yield response was consistent. This research has shown a need for the re-evaluation of fertilizer recommendations in direct-seeding systems since typical crop responses to MAP and KCl fertilizer addition was not evident. For example; toxicity did not occur with high rates of MAP in the wheat or flax, the 'pop-up' effect from seed-placed MAP fertilizer did not occur and yield advantage from KCl addition occurred only at the clay loam location. These results may be attributed to direct-seeding, changes in available nutrients from long-term fertilization and/or the presence of wild oats. (Abstract shortened by UMI.)