LABORATORY SOIL FERTILITY RECOMMENDATIONS AND COST COMPARISON IN SEVIER COUNTY, UTAH
Agronomy & Pest Management
Jody Gale
Sevier County & Central Southwest Area Agent
Utah State University Extension
Richfield
Abstract
Adequate soil fertility is needed by agronomic crops to maximum yield and economic potential. Lack of one or more soil nutrients will reduce crop yield and farm income. Applying excessive fertilizer and needless soil amendments increases environmental degradation potential and reduces farm profitability. Periodic soil testing is needed to ascertain soil nutrient levels, establish fertility trends, and acquire essential analytical information necessary to make good soil fertility decisions. Growers, crop consultants, and extension agents rely on accredited private and university laboratories for soil analysis. However, laboratory recommendations and associated fertilizer cost per acre can vary significantly. Private laboratories typically take a soil building approach, whereas universities use a sufficiency approach. No-cost soil sampling and analytical services are frequently provided by commercial soil fertility services using private accredited soil analytical laboratories. Sales based incentivized recommendations can be excessive. Ongoing fertilizer supply chain issues have significantly increased fertilizer prices, further reducing farm profitability. The Utah State University (USU) Extension Agronomic Crops Team is conducting a statewide, three year, on-farm research study with 12 cooperators. In this study soil fertility recommendations and costs are being evaluated. Soil samples from candidate research fields were analyzed by three accredited private laboratories and two accredited university laboratories. Using a standard replicated research plot design, macro and micro fertilizers were applied at respective laboratory recommendation rates for five experimental treatments and a control. Plots were harvested using cooperator field scale equipment. Alfalfa yield response and quality were measured by weighting 10’ of the windrow, sampling forage, oven drying samples and analyzing for quality. In the Sevier County trial, the yield in tons per acre for 2021 and 2022 respectively for private lab recommendation #1 was 4.32 (2021) and 6.57 (2022), #2 was 4.49 and 6.62, #3 was 4.84 and 6.45, #4 Utah State University (USU) was 4.36 and 5.79, #5 University of Idaho (UOI) was 4.46 and 6.42, and the control was 4.33 and 5.83 respectively. The cost per acre of the respective treatments from private lab #1 was $251 (2021) and $440 (2022), #2 was $157 and $248, #3 was $784 and $1,035, #4 USU $74 and $191, and #5 UOI $177 and $434. Yield difference between some of the treatments were observed but they were not often statistically significant. The unfertilized control did yield lower than the other treatments, indicating that fertilizer did increase alfalfa yield. There was no statistically significant difference in quality between treatments. The results from a separate replicated soil amendment study showed no significant difference in yield to applications of sulfur and gypsum.
Authors: Jody A Gale, Matt Yost, Megan Baker
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Jody A Gale Sevier County & Central Southwest Area Extension Agent, Utah State University - Extension, Utah, 84701
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Matt Yost Agroclimate Extension Specialist, Utah State University - Extension, Utah, 84722
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Megan Baker Graduate Research Assistant, Utah State University - Extension, Utah, 84722