RESIDUAL EFFECTS OF FABA BEAN AND SOYBEAN FOR A 2ND OR 3RD SUCCEEDINGFORAGE-CORN PRODUCTION

Many studies have been conducted on the effects of annual legumes on s ubsequent corn production but they rarely extended beyond a second suc ceeding crop. We have therefore conducted field experiments on a sandy gravelly loam at St-Anselme and on a silty loam at Deschambault in ea stern Quebec to determine the residual effects of (i) faba bean (Vicia faba L.) and soybean (Glycine max [L.] Merr.) on a third succeeding c orn (Zea mays L.) crop and (ii) 2 consecutive years of these legumes o n a second subsequent com crop. In monoculture or following legumes, c orn was fertilized with 0, 50, 100 or 150 kg N ha-1 as NH4NO3. The com stover and whole-plant dry matter yields (DMY), and the ear and whole -plant N uptake were higher following faba bean grown 3 years earlier than in monoculture at both locations. At Deschambault, the stover DMY of second subsequent corn following 2 consecutive years of faba bean did not vary with the N application. At both locations, the DMY, N con centrations and N uptake of second subsequent com were higher after 2 consecutive years of faba bean than after other previous crop sequence s. Two consecutive years of soybean had significant effects on the DMY and N uptake of a second subsequent com crop with N application at De schambault. At both locations, the N-fertilizer replacement values (NF RV) of soybean were lower or equal to 0 kg N ha-1. The NFRV (DMY and N uptake bases) of faba bean grown three years earlier and of 2 consecu tive years of this pulse varied widely between locations.