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Advanced soil tests can improve the estimation of plant available nutrients to better match fertilizer additions with plant needs and, in some cases, provide a measure of soil health. In the present study, 334 samples from four separate studieswere evaluated using the Soil Health Tool (SHT) vs. the standard regional (University of Idaho [UI] Guidelines) method for determining fertilizer application, assuming a crop of spring irrigated wheat. Recommended N applications using the SHT were ~138 kg ha-1 greater than the UI recommendations. Nitrogen mineralization predicted using the SHT (47 kg ha-1) was similar to the N mineralization value used in the regional methodology (50 kg ha-1). The P fertilizer recommendations were similar between the two methodologies with the SHT recommending, on average 4.7 kg ha-1 less P than the regional method. The lower P recommendation are likely due to a lack of accounting for the effects of high calcium carbonate levels on the P availability from fertilizers in this region. The soil health score (SHS) was correlated with measures of soil C but was not positively correlated to crop yield. In some instances, increasing SHS were correlated with decreases in crop quality as the addition of manure increased soil C but also created issues such as high salt contents and release of late season N. With modification to more accurately represent irrigation conditions and including sampling to greater soil depths, the SHT may be tailored to better estimate soil nutrient status and provide better fertilizer recommendations for the region. [ABSTRACT FROM AUTHOR]

Information on the effects of phosphorus (P) and sulfur (S) applications on crop response and soil-P status of two-row malt barley (Hordeum vulgare L.) under high-input conditions are limited in alkaline soils despite widespread fertilizer-P and -S use. A field study was conducted during the 2015 and 2016 growing seasons where the barley cultivars (ABI-Voyager and Moravian 69) were grown at five rates of P (0, 37, 73, 110, and 147 kg P ha−1) and three rates of S (0, 112, 224 kg S ha−1). ABI-Voyager had significantly greater biological yield (17,023 kg ha−1) and grain yield (7433 kg ha−1) but a lower (44%) harvest index (HI) than Moravian 69 (15,037 kg ha−1, 7168 kg ha−1 and 49%, respectively). Grain yield increased with rate of P-application until 37 kg P ha−1 where the maximum calculated yield was obtained at 98 kg P ha−1 by a quadratic model. Sulfur application had no significant effect on any of the measured crop or soil parameters. Olsen P increased linearly with greater fertilizer-P applications, indicating grain-P removal was not sufficient to reduce or retain STP concentrations at initial levels when P was applied. Crop-P uptake and soil-P response to fertilizer P applications are important, as remaining soil P is available for subsequent crop usage and may have potential negative environmental impacts. Thus, cultivar selection and appropriate fertilizer-P and S management will ensure optimal agronomic and economic returns while minimizing potentially negative environmental impacts for two-row malt barley produced in the western United States. [ABSTRACT FROM AUTHOR]

Soil P testing is critical to ensure the accuracy of fertilizer recommendations and to optimize crop yield while minimizing negative environmental consequences. Olsen-P is the most commonly used soil P test for alkaline calcareous soils found in Idaho and the western United States. The Bray-1 test is commonly used in the Pacific Northwest on neutral to acidic soils but underestimates P in alkaline calcareous soils. Mehlich-3 has been evaluated throughout various regions in the United States. Few data evaluating Mehlich-3 exist for soils in the western United States. Additionally, the comparatively newly developed Haney–Haney–Hossner–Arnold (H3A) test, a component of the soil health tool, has not been widely evaluated on alkaline calcareous soils. Soil samples from the 0- to 30-cm depth were collected from agricultural fields throughout Idaho and analyzed with Bray-1, H3A, Mehlich-3, and Olsen-P extractants. The results indicate that Olsen-P was correlated with Mehlich-3, whereas Bray-1 and H3A were not correlated with Olsen-P. Both Bray-1 and H3A resulted in lower values of extractable P than the Olsen-P test, whereas Mehlich-3 resulted in greater values. A threshold point in CaCO3 (i.e., inorganic C) of 6.7 and 5.1 mg kg-1 for the Bray-1 and H3A was obtained, respectively, which indicated that inorganic C concentrations at or above these levels resulted in a reduction in extractable soil P. Thus Mehlich-3 could be evaluated for use in alkaline calcareous soils, whereas Bray-1 and H3A have notable issues that would limit their applicability. [ABSTRACT FROM AUTHOR]