Manganese relationships in spring wheat and spring barley production in Northern Idaho

Abstract

Manganese is often limiting in cereal crop production in the Kootenai River Valley of Northern Idaho; however, attempts to relate DTPA‐extractable Mn in soils to crop yield response have not been successful. Consequently, Mn plant tissue diagnosis may be an alternate diagnostic tool. The objectives of this study were to: (1) determine the critical nutrient concentration (CNC) of Mn in spring wheat and spring barley tissue in the Kootenai River Valley of northern Idaho, (2) examine yield response of spring wheat and spring barley to Mn fertilization, and (3) assess relative efficiencies of foliar and surface broadcast Mn applications to these crops. Paired plots with four replications consisting of a foliar Mn application rate of 1.5 kg ha^‐1 and a control were located at four sites in 1988 and at ten sites in 1989. Soil, plant tissue samples and grain yield data were evaluated by linear plateau regression to determine CNCs of Mn for spring wheat and spring barley tissue. In addition, five randomized complete block experiments were conducted in 1989 and 1990 to evaluate Mn fertilizer rates and sources (foliar vs. surface applied) on spring wheat and spring barley production. Tissue Mn was highly correlated by linear plateau regression to both spring wheat (r² = 0.74**) and spring barley (r² = 0.70**) grain yield. The Mn CNC was established at 11.0 mg Mn kg‐¹ plant tissue for spring wheat and 10.1 mg Mn kg^‐1 plant tissue for spring barley. The Mn CNCs were established at 92.4 and 93.0% of maximum yield for spring wheat and spring barley, respectively. DTPA‐extractable Mn was not significantly correlated to grain yield for either crop (r² = 0.02, NS). Based on study results, Mn analysis of spring wheat and spring barley plant tissue was diagnostic of eventual grain yield. When tissue diagnosis showed plants to be deficient in Mn, the deficiency was corrected by applying Mn fertilizer as a surface broadcast or a foliar spray. However, foliar application of Mn was more efficient than broadcast application.