Objectives
- Demonstrate flax yield response to a range of nitrogen fertilizer rates for a variety of Saskatchewan locations.
- Demonstrate the seed-safety and potential yield benefits of polymer coated urea (ESN) relative to urea when side-banded at high rates.
- Demonstrate the potential merits of utilizing split-applications of nitrogen in flax to reduce the likelihood of seedling injury and lodging while potentially enhancing yield.
Project Description
Although environmental conditions were not ideal, we were still successful in achieving many of the stated objectives and demonstrating flax responses to N fertilizer rates and non-traditional management practices with respect to establishment and yield. Focusing on establishment, the results were consistent with past Prairie research whereby emerged declined as the rate of side-banded urea was increased at 67% of the locations, the sole exceptions being Indian Head and Yorkton. The magnitude of the declines in plant densities ranged from 34-107 plants/m2, or 11-31%. As hypothesized, these losses were either greatly reduced or eliminated by substituting untreated urea with a 75:25 blend of ESN® and untreated urea or with split-applications where a portion of the N was side-banded and the remainder supplied as an in-season surface-broadcast application. The downside to these approaches is that ESN® results in higher input costs due to the premium price associated with this product relative to untreated urea and split-applications result in added costs due to the extra labour, fuel, and equipment wear-and-tear associated with in-crop applications. Furthermore, crop responses to in-crop N are less consistent to in-soil bands applied before or during seeding due to the higher risk of volatilization and need for subsequent precipitation to move the N into the rooting zone. When considering the potential negative effects of side-banded N on flax establishment, producers should consider the relative costs, benefits, and risks of simply increasing their seed rates as opposed to utilizing ESN® or split-applications.
Lodging is a concern that is frequently reported by commercial flax growers which is typically more severe with high N fertility. We had anticipated that this may be alleviated to some extent by split-applications of N; however, no lodging was observed under the specific environmental conditions encountered. Past research/demonstration activities and testimonials suggest that lodging in flax may also be reduced with early seeding and/or foliar fungicide applications.
Focusing on seed yield, responses to N fertilization were less consistent than expected, primarily due to the dry conditions and subsequently low, variable yields. Significant yield increases with N occurred at Indian Head, Melfort, and Redvers, but not at Swift Current, Scott, or Yorkton. In the cases where responses occurred, the rate where yields were maximized ranged from as low as 55 kg N/ha at Redvers to 105 kg N/ha at Indian Head. There was never any benefit to going as high as 130 kg N/ha, the top rate evaluated in this demonstration. To a large extent, this variation in responses could be explained by the combination of residual soil N and the actual yield potentials that could be realized based on environmental conditions. At Indian Head, where the strongest responses to N were achieved, yields were low but the initial potential was reasonably high and residual N was the lowest of all six locations. At Melfort, residual N was moderately high but yield potential was the highest of the locations and the yield response to N was intermediate. At Redvers, where yield potential was low (similar to Indian Head) and residual N levels were modest, 55 kg N/ha was sufficient to maximize yields. At Swift Current and Yorkton, residual N levels were high, yield potential was low, and no responses to N application were detected. Scott was somewhat more of an anomaly in that residual N was reasonably low and overall yields were similar to Indian Head (the most responsive location), but no response to N was detected. Despite the advantages with respect to establishment, there were no yield benefits to either ESN® or split-applications of N. Focusing on split-applications , yields were always similar regardless of application time; however, one location (Swift Current) did appear to benefit from utilizing Agrotain® treated urea over untreated urea as the in-crop source, despite there being essentially no response to side-banded.
It would be beneficial to evaluate these treatments under more typical growing conditions where environmental conditions are more favourable for flax productions and, ideally, residual N levels are consistently lower.
