Assessment of Compost on Dryland Wheat Yield and Quality, Soil Fertility and Water Availability in Utah

In 2014-2016 Kareem Adeleke undertook a graduate project under the supervision of Utah State University (USU) Plants, Soils and Climate professors, Drs. Jennifer Reeve, Astrid Jacobson, and Earl Creech. Organic wheat producers face numerous challenges, such as low soil moisture, soil erosion, and low soil fertility. Organic wheat growers generally do not apply fertilizer due to inability to recoup the costs in the short-term. Compost enhances long-term improvement in soil quality, soil fertility and increase yield in low input environments. Understanding of compost carryover effects in dryland wheat systems is necessary for increased yield that will allow adequate supply of nutrients for several years after the initial application. A previous study on a Utah calcareous soil showed evidence of soil benefits twenty-two years after a single application of compost at 50 Mg ha-1 dry weight. A new experiment was started at the Blue Creek farm in 2011 to test the reproducibility of these findings on a less marginal soil type. Compost was applied at 0, 12, 25, and 50 Mg ha-1 plus a conventional fertilizer control. Wheat yield was significantly increased three years after application at the 50 Mg ha-1 compost rate only. Conventional fertilizer increased grain protein. Mineralizable soil carbon, microbial biomass and phosphatase enzyme activity increased significantly at all compost rates, while available soil phosphorus increased at the 25 and 50 Mg ha-1 rates and total soil nitrogen at the 50 Mg ha-1 rate. A lack of yield response to conventional fertilizer suggests improved soil health and or soil moisture was responsible for improved yields at the high compost rate