Response of Two Malt-Barley Cultivars to Phosphorus and Sulfur Application in an Alkaline Calcareous Soil.

Malt barley (Hordeum vulgare L.) is grown extensively in southeastern Idaho. The region is characterized by high pH calcareous soils. However, phosphorus (P) availability is generally at a maximum in the soil when the pH is in the 6.0 to 6.5 range. In high pH calcareous soils, calcium phosphate compounds predominate and can effectively fix P in a relatively unavailable form in terms of plant growth. However, elemental sulfur (S) has acidifying properties that may provide positive benefits concerning P availability for plant growth. Research was conducted at the Aberdeen Research and Extension Center on a Declo loam (coarse-loamy, mixed, superactive, mesic Xeric Haplocalcids). The objectives of this study was to determine barley responses to P and S fertilization. Malt barley (Hordeum vulgare L.) varieties, Moravian 69 (short statue) and AB Voyager (standard statue) were planted in spring 2015. Five P (0, 37, 74, 111, and 148 kg P ha^-1) and three S (0, 112, and 224 kg S ha^-1) rates were applied to the two varieties at planting. Plant shoots and roots were sampled eight weeks after planting in each plot. Averaged across phosphorus and sulfur application rates, shoot biomass of Moravian 69 (994 g m^-1) was less than AB Voyager (1551 g m^-2). Averaged across cultivar and sulfur application rate, shoot biomass increased with P application where biomass averaged 1506 g m^-2 from rates of 74, 111, and 148 kg P ha^-1, which did not differ. Root dry weight and root length density differed between cultivars and fertilizer application levels. Results of the current study provide evidence of the influence of fertilizer applications on malt-barley root and shoot components that improve our understanding of the interaction of these fertilizer sources for use in malt barley production on alkaline calcareous soils.