EFFECTS OF RATES AND PLACEMENT METHODS OF UREA AND POTASSIUM-CHLORIDEON SOIL-NITROGEN AND POTASSIUM AND CORN DRY-MATTER YIELD

Placement and interaction of urea and KCl fertilizers for com producti on needs to be evaluated to develop rational fertilizer management pro grams. A field study, involving three rates of urea and KCl with band and broadcast placements, was conducted with corn on two Quebec soils in 1988 and 1989 to determine nutrient interactions on corn (Zea mays L.) dry matter yields, N and P uptake and on soil N and K. In two site s (Chicot 1988 and Ormstown 1989) with dry surface soils, no rainfall for 5 d and significant rainfall after 5 d, broadcast urea resulted in higher dry matter yields and uptake of N than banded urea. In the Chi cot 1989 site where urea application was on moist soil and followed by rainfall insufficient to move broadcast urea into the soil, banded ur ea was more effective than broadcast urea. Banded urea generally resul ted in increased inorganic N and fixed NH4+ in soil sampled from withi n fertilizer bands but lower levels in soil between bands in compariso n with broadcast urea. Banding KCl resulted in increased exchangeable K+ in the band. Compared with exchangeable K+, fixed K+ was less affec ted by placement methods and rates of added N and K. Interactions betw een rates and placement methods of N and K on dry matter yield, N and K uptake and soil N and K were few and relatively small.