Relationship between soil-test boron and lentil yields in the inland Pacific Northwest

Critical soil- test boron ( B) levels and consequent fertilizer recommendations for lentils have been traditionally based on values ( 0.5 mg/ g) developed for alfalfa, sweet clover, and other legumes commonly grown in the inland Pacific Northwest. The purpose of this study was to define the relationship between soil- test B values and lentil yields. Fifty- nine field studies using B were conducted between 1980 and 2003 on Mollisols and Alfisols in northern Idaho and eastern Washington. Based on the results of these studies, the critical soil B value for optimum lentil yields is 0.4 mg/ g. These studies found that the traditionally used critical soil- test B values were higher ( 0.5 mg/ g) than needed to achieve optimum yield. Even though this newly established critical B value is lower, about 50% of the soils in the region are too low in B to produce optimum lentil yields.