Variable rate nitrogen fertilization in the Black Soil Zone of Saskatchewan
van Kessel, C.
The feasibility of variable rate N fertilization was assessed during a single growing season at Birch Hills, Saskatchewan, Canada (105” 2’ W, 53” 3’10 N). The experiment was carried out across a 120 m x 620 m wheat field, which was divided into twelve 10 m x 620 m strips. Each strip was further broken down into 10 m x 10 m grid cells. Each of these grid cells was assigned to one of three possible management units based on their topographical characteristics. Prior to fertilization, initial soil testing was carried out; ten surface soil samples from each management unit were collected and analyzed for available N and P. The spring nutrient data, along with two separate growing season precipitation scenarios, were used to develop the fertilizer recommendations. At seeding each of the strips was fertilized in accordance to one of the two growing season precipitation scenarios or at a constant, or conventional, rate. Soil mineral N and available moisture was measured at ninety benchmark sites prior to seeding, weekly through the crop vegetative state, and following harvest. These benchmark sites were evenly distributed among management units and fertilizer rates. Crop yield was also measured at each of the ninety benchmark sites. Preliminary results indicate that fertilizer responses varied between management units. These observations suggest that fertilizer application can be manipulated on the basis of landscape - scale management units to minimize inputs, while maintaining yield.
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