Wednesday, November 7, 2007
296-11

Soybean Response to Boron Fertilization in Arkansas 2002-2007.

Russell DeLong1, Nathan Slaton1, Bobby Golden1, Joni Ross1, Morteza Mozaffari2, and Leonel Espinoza1. (1) University of Arkansas, 1366 W. Altheimer Dr., Fayetteville, AR 72704, (2) PO Drawer 767 Hwy. 1 South, University of Arkansas, Univversity of Arkansas, Soil Test Laboratory, Marianna, AR 72360

Boron fertilization of soybean [Glycine max (Merr.) L.] grown on alkaline silt and sandy loam soils is now a common, recommended practice in northeast Arkansas. The primary objective was to summarize research conducted from 2002-2007 at 24 site-years to evaluate soybean tissue-B concentrations and seed yield responses to B fertilizer applied at planting as granular B or post-emergence as B solutions at vegetative or reproductive growth stages. Soil-test data have not been able to identify soils that will respond to B fertilization. Soybean growing in areas where the previous year’s drain furrow and barrow ditches were located tend to have better growth and fewer B-deficiency symptoms suggesting the likelihood that B deficiency may increase as tillage decreases. Overall, 6 of 24 sites showed consistent, positive yield responses to B with yield increases ranging from 6 to 133% of the yield produced when no B was applied. Yield data suggest that early-season preventative B applications usually produce greater seed yields than B applied at the onset of reproductive growth. The magnitude of yield response from B-deficient soybean to foliar B application may diminish as the duration of B deficiency is prolonged. Trifoliate leaf B concentrations at the R2 growth stage explained 51% of the variation in relative yield among sites and predicted a critical B concentration of 22 mg B/kg for production of 90% relative yield. The cost of B fertilizer is relatively small and the potential returns to maximize seed yield can be quite significant if B is applied to soybean grown on alkaline silt loam soils in areas where B deficiency has been a common problem.