Tm. Reinbott et Dg. Blevins, RESPONSE OF SOYBEAN TO FOLIAR-APPLIED MAGNESIUM AND SOIL-APPLIED BORON, Journal of plant nutrition, 18(1), 1995, pp. 179-200
Annual plants may partition carbon (C) preferentially to reproductive
structures slowing root elongation and subsequent nun-lent uptake. Alt
hough foliar applications of nitrogen (N), phosphorus (P), potassium (
K), and sulfur (S) supplement uptake by roots, soybean [Glycine max (L
.) Merr.] yield increases have not been found in most studies. Experim
ents were designed to determine if foliar applications of boron (B), m
agnesium (Mg), or B+Mg would increase soybean yield and if soybean wou
ld respond to B applied to the soil several weeks prior to planting. F
oliar B or Mg applied separately four times during reproductive growth
did not affect soybean yield. However, four foliar applications of BMg increased soybean yield 12% at hit. Vernon and 4% at Columbia over
a three-year period. Two foliar applications of B+Mg during the late r
eproductive stages increased soybean yield 8% over a two-year period.
The yield increase from foliar B+Mg treatment resulted from an increas
ed number of pods on the main stem (18%) and branches (44%). A 2.8 kg/
ha B application to soil eight weeks prior to planting increased soybe
an yield 11% during the first year and 13% the second year but had no
effect on soybean yield by the third year after application. When resu
lts from the first two years were combined, 2.8 kg/ha B applied to soi
l increased the number of pods per branch by 17% and the number of bra
nch pods per plant by 39%. Foliar applications of B+Mg increased soybe
an yield in four of six site-years in the three-year experiments at tw
o locations.