ZINC NUTRITION OF SILAGE CORN GROWN ON ACID PODZOLS

Field studies were conducted at Bouctouche Research Farm in New Brunsw ick, Canada to determine the effect of zinc (Zn) and nitrogen (N) on s ilage corn. Soils at these sites are coarse texture loamy sand with pH values of 6.0-6.3 and organic matter content of 2.6 to 2.7 mg . g(-1) . In Experiment 1, Zn application at 0.5 to 1.0 kg . ha(-1) foliar or 10 to 20 kg . ha(-1) soil applied significantly increased the silage c orn dry matter yield. Leaf Zn levels of 8.8 to 10.1 mg . kg(-1) and av ailable soil Zn at 0.8 mg . kg(-1) in the check treatments were relate d to Zn deficiency in corn. No response to Zn was noted in Experiment 2 and this was associated with leaf Zn levels of 15 to 16 mg . kg(-1) in the control treatment. In the Zn x N field study, a significant dry matter yield response to N and Zn was obtained. Nitrogen applications with or without added Zn increased leaf Zn. Leaf Zn increases were hi ghest at the highest rate of added N. Corn leaf Zn levels at 9 mg . kg (-1) were associated with lower yield. Zinc deficiency in corn can be controlled by 1 kg Zn ha(-1) foliar or 10 to 20 kg Zn ha(-1) soil appl ied.