Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: October 22, 1998
Publication Date: N/A
Technical Abstract: US crop producers apply > 2.5 billion kg of P to agricultural lands each year. In most instances the amounts of P applied are based on recommendations associated with conventional soil testing methods. In a field study, soybean was grown in a maize, wheat, soybean rotation in 1.1 ha areas which were subdivided into 360 3 by 10 m plots containing four rows at 0.75 m spacing. Soils were sampled and extracted with ion exchange resins and the extracts were assayed with ICP determination methods. Seed yield was different between variety and soil mapping unit. Seed yield was adversely correlated with extractable V content and the correlation was improved when data were regressed as a function of the V:(V+P) molar ratio. Vanadium is a potent inhibitor of plasma lemma ATPase (necessary for mineral nutrient accumulation by plants) but it is rarely surveyed in soils. Soil mapping units within the experimental site differed in both their resin extractable P and V contents. Conventional methods of soil chemical analyses are usually inadequate to characterize complex nutrient interactions. The amounts of P needed for optimal nutrient use efficiency must be adjusted for the extractable V:(V+P) ratio.