Relationship between Soil Test Boron and Pea Yields in the Inland Pacific Northwest

Abstract

Critical soil test boron (B) levels and consequent fertilizer recommendations for spring peas have been traditionally based on values developed for alfalfa, sweet clover, and other legumes commonly grown in other regions of the USA. The purpose of this study was to define the relationship between soil test B values and spring pea yields. Seventy‐eight field studies using B were conducted between 1981 and 2001 on Mollisols and Alfisols in northern Idaho and eastern Washington. Soil sampling to the effective rooting depth of 0.6 m for spring peas results in the best relationship between soil test B and spring pea yield; however, samples taken to the depth of 0.3 m result in the same B critical value (0.5 µg/g). Based on these field studies, the data clearly demonstrate that the 0.5 µg/g critical soil test value of B is important for spring pea yield optimization.