Application of seed-row potash to barley (Hordeum vulgare L.) grown on soils with high “available” potassium levels

Benefits of KCl application to cereals have been documented in Great Plains soils and have been attributed primarily to a response to the Cl- portion of this fertilizer either due to disease suppression or a Cl- deficiency. The practice of placing small amounts of KCl with the seed to avert any of these undesirable effects has been gaining momentum in western Canada. However, research on benefits from KCl fertilization of barley on high K soils in western Canada is limited. A large number of trials (115) were conducted from 1989 to 1998 on western Canadian prairie soils to ascertain the response of barley to seed-row applied KCl fertilizer. All soils contained K levels in excess of what is considered a critical level for obtaining a yield response to K due to K deficiency. Statistically significant yield increases with KCl application were obtained in 37 of 115 trials (32%). There appeared to be a strong link between the probability of obtaining a significant yield response to seed-row applied KCl, and barley cultivar and previous crop. Growing Harrington barley on barley stubble resulted in a grain yield increase due to KCl seed-placement 60% of the time. However, no clearly defined mechanism for the grain yield responses could be drawn based on the determined parameters, except that the majority of responses did occur under conditions that promote disease (e.g., disease susceptible cultivar, barley sown on barley stubble, etc.) and that the lower the soil "available" K levels in those instances, the higher the grain yield increase. Hence, it is hypothesized that K may play an indirect role in suppressing disease by increasing the overall health of plants. None of the assessed plant characteristics other than yield, i.e., days to maturity, kernel plumpness, protein and root rot infection, benefited from application of Cl- as either KCl or CaCl2.