Search

Although crop production and weed growth could change if herbicides and fertilizer inputs were reduced, the short-term impact in an annual cropping system in the Northern Great Plains is not well understood. Data were collected from 14 sites in Saskatchewan, Canada, to investigate the influence of weed control method (cultural vs. herbicides) and N and P fertilizers on crop yield of fall rye, spring wheat, and barley, and the presence and number of weed species. Cultural weed control included 25% greater crop seeding rate, preseeding tillage closer to the time of seeding, and fertilizer N banding in closer proximity to the seed. Four weed species (wild oat, lambsquarters, wild buckwheat, and field pennycress) occurred more frequently in plots with cultural weed control compared with herbicide weed control for all cereal crops. However, straw and grain yields of all crops were unaffected by weed control method at all sites. The addition of fertilizer had a major impact on crop growth and some weed species. Green foxtail occurred more often in unfertilized compared with fertilized plots for all cereal crops. Straw and grain yields of all cereal crops were higher in fertilized compared with unfertilized plots. Crop yield response to fertilizer inputs was not consistent among sites for the three cereal crops. Producers making drastic reductions in fertilizer inputs may experience reductions in crop yields because of limited nutrient levels. However, the results indicate that herbicide inputs could be reduced or eliminated periodically with no short-term yield loss in cereal cropping systems. Key words: cereal crop yields, cultural practices, N and P fertilizers, weed presence

The influence of agronomic variableson soil light-fraction (LF) material content and the capacity of the LF as a measure for labile organic matter is discussed. Soil samples obtained from longterm crop rotation studies with similar management practices at three sites in Saskatchewan, Canada were subjected to light-fraction analysis. The sensitivityof LF as an indicator of short-term effects of cropping on soil organic matter content and composition was demonstrated.