Submitted to: International Conference on Precision Agriculture Abstracts & Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: July 22, 1998
Publication Date: N/A
Technical Abstract: In order to realize benefits of differences between soils, two goals must be accomplished: 1) testing methods must be developed which describe differences between soils and 2) plant varieties or hybrids must be developed which respond to these differences. A 3.3 ha field experiment was designed to test whether 1) resin extractions (RE) could distinguish immediately adjacent soil mapping units and 2) soil mapping units interacted with soybean variety. Soils were Buse loam, Barnes loam, Hamerly clay loam, Svea loam, and Parnell silty clay loam. The area was divided into three 1.1 ha plots which were further divided between 360 plots measuring about 3 m by 10 m. Commercial varieties of soybean were grown in 0.75 m row spacing. Soil samples were taken in selected plots, extracted with resins, and the extracts analyzed by ICP. Resin extractions show that each soil was distinguished by its suite of extractable ions. Seed yield results showed that the varieties responded differently to different soils. Examination of the results showed a complex correlation between yield for a variety and the molar ratio of V:(V+P). Soybean yields from the Buse loam < Barnes loam even though both occupy similar landscape positions. Seed yields varied from 2.65 to 3.60 Mg per ha but were positively correlated with RE-P or bicarbonate extractable-P. Seed yields were negatively correlated with extractable V for two varieties. Conventional techniques for chemical evaluation of soil are unable to identify these complex relationships. All plots were considered 'upper medium' to 'high' in relative bicarbonate-extractable P levels; however, P addition on the Buse loam is predicted to enhance soybean seed yield.