BANDING UREA AND LIGNOSULFONATE IN CORN (ZEA-MAYS L) PRODUCTION AND N-15 RECOVERY

The use of urea in corn (Zea mays L.) production is common. Under curr ent N fertilizer recommendations for corn, urea may have adverse effec ts on corn growth when applied in a band. The effects of ammonium lign osulfonate (LS) on corn growth and on N uptake from the banded applica tion of urea and diammonium phosphate (DAP) mixtures were investigated on two soils from eastern Quebec. Field experiments were initialed in the first week of May 1991 on an Ormstown silty clay and a Ste. Rosal ie clay soil; (fine, mixed, nonacid, mesic Typic Humaquepts). Treatmen ts were two rates of urea (30 and 90 kg urea-N ha(-1)) in combination with DAP (14 kg N ha(-1)), with or without banded fertilizer solutions of LS (8 kg N ha(-1)) applied at planting 5 cm to the side and 3 cm b elow the seed. A no treatment control was included. The low rare of ur ea and DAP (no LS added) resulted in a 19 and 24% increase in grain yi eld at the Ste. Rosalie and Ormstown, respectively, when compared with the unfertilized plots. When compared with the unfertilized treatment , the high rate of urea and DAP (no LS added) caused 10% increase in g rain yield. However, addition of LS to the high rate of urea and DAP i ncrease grain yield by band 20%. In general, LS significantly increase d corn N uptake from urea on both soils. Separate N-15 field experimen ts were initiated in June 1991. Mean recovery of N-15 in total dry mat ter (grain and stover) was 51.9% in Ormstown and 47.9% in Ste. Rosalie soil. Denitrification estimates, calculated as N-15 not accounted for , were not affected by LS and the rate of banded urea-N. Immobilizatio n of N-15 ranged from 17.8% to 30.9% of the applied labelled urea. The rate of urea-N banded had no significant effect on immobilization, bu t LS resulted in significantly less N-15 immobilized. These observatio ns suggest that LS can reduce the biological immobilization of urea-N and increase the efficiency of urea fertilizer by reducing the negativ e effects of banding high levels of urea, while attaining benefits of band placement.