Field Studies Comparing Nutrient Availability in Low Fertility Soils Using Ion Exchange Resin Capsules and Conventional Soil Tests.

Field Studies Comparing Nutrient Availability in Low Fertility Soils Using Ion Exchange Resin Capsules and Conventional Soil Tests

Mary P. Jones, Von D. Jolley, Bruce L. Webb, Matthew D. Vickery, Rachel L. Buck and Bryan G. Hopkins, Plant and Wildlife Sciences, Brigham Young University, 275 WIDB, Provo, UT 84602.

Ecosystem establishment following disturbance requires better understanding of nutrient status in desert soils often low in nutrients. Commonly used soil analysis procedures were developed to assess nutrient status in fertile agriculture soils and their validity in desert ecosystems is uncertain. Resin capsules and standard soil tests were effective in measuring low P and N levels in incubation and greenhouse studies, but effectiveness under field conditions is unknown.  Field studies were established in Rush and Skull Valleys in Utah on a clay loam soil and sandy loam soil, respectively. Two m² plots received surface application with slight incorporation of six N and P combinations with five replications of each treatment in a completely randomized block design with granular triple superphosphate (0-45-0) and ammonium sulfate (20-0-0) as fertilizer sources. One resin capsule per plot was placed at a depth of 5 cm in the soil in May 2009, prior to fertilizer application and was removed and replaced approximately every 90 days over one year. Soil samples were taken to 5 cm as resin capsules were removed. Data after the initial 90 day period suggest that resin capsules are more effective in reflecting the amounts of nitrate and ammonium applied to the fine than to the coarse textured soil.  Traditional soil tests are equally effective in reflecting the amount of ammonium, nitrate and P applied to fine and course textured soils in dry land conditions. More relationships among nutrient application levels and extracted nitrate, ammonium and P were significant with conventional soil tests than with resin capsules. Our poster will present additional data from the four sampling periods.