Objectives
- To demonstrate the potential response (or lack thereof) to applications of potassium (K) and sulfur (S) fertilizer alone and in combination.
- To demonstrate the relative performance of three high yielding flax varieties.
- To explore whether the potential for responses to these important, albeit less commonly limiting, macronutrients differed across varieties.
Project Description
This project has demonstrated both the relative performance of several popular flax varieties and provided a forum for discussion on balanced fertility in flax production.
The varieties showcased were the popular check variety, CDC Bethune, and two newer varieties CDC Glas and CDC Neela. While the differences were modest in absolute terms, the observed variety performance rankings were consistent with those from the previous year showing statistically significant yield advantages to the newer varieties. This supports the recommendation that growing modern, regionally adapted varieties is an important component of achieving top flax yields. Averaged across zones, the provincial variety guide rates the yields of CDC Glas and CDC Neela as 105% and 104% of Bethune which is consistent with the current results where the yields were 110% and 106% of Bethune for CDC Glas and CDC Neela, respectively. Established plant populations were similar across varieties and not considered potentially limiting to yield ranging from 386-410 plants/m2 – the recommended minimum flax population is 300-400 seeds/m2. Focusing on fertility, flax establishment was not affected by the K/S treatments but this was not unexpected given that all K and S fertilizer products were side-banded as opposed to seed-placed. Spring soil tests from the site showed residual levels of 762 ppm of extractable K in the top 15 cm of soil and 57 kg S/ha (0-60 cm); therefore, did not necessarily suggest that applications of these nutrients were likely to improve yields. Consistent with the soil test predictions, neither K nor S fertilization impacted flax yield, regardless of variety, form or combination with other nutrients. While K deficiencies are rate in most Saskatchewan soils, some growers/agronomists see applying some fertilizer as important for maintaining soil productivity over the long-term and, with some crops (i.e. canaryseed) responses specifically to the Cl component of potash have been documented. While S is not commonly limiting for most crops either, deficiencies do occur and challenges arise in that this nutrient is difficult to accurately test for due to high spatial variability and mobility. While low soil test results for S can generally be relied upon, high test values are often suspect and, when growing sensitive crops (i.e. canola) or if deficiencies have been observed in the past, it is often recommended to apply small quantities of S regardless of soil test results. Overall, growers are recommended to take into account soil test results, past experience and long-term fertility objectives when determining whether to apply K and S fertilizer when growing flax
