EFFECTS OF FORAGE OATS PLANT PARTS (Avena strigosa Schreb.) AND OF MTROGEN FERTILIZING SYSTEMS ON DEVELOPMENT AND GRAIN YIELD ON CORN (Zea mays L.) ESTABLISHED IN NO-TILL

Abstract

Maximum benefits of no-tilled summer crops are obtained when winter species are used to cover the soil with straw to prevent soil erosion. Forage oats is the main species utilized as cover crop in Rio Grande do Sul State, Brazil. One experiment was conducted at Experimental Estation of UFGRS, in Eldorado do Sul, RS, during 1996/97, with the objective to evaluate com yield and development when established on forage oats plant parts and with nitrogen fertilizing systems. Treatments consisted of four cover systems established before com seeding (com seeding on whole oats plant straw, oat roots, oat shoots, and bare soil); as well as four nitrogen fertilizer systems (0/0, 30/90, 60/60 and 0/120 kg/ha of N at start/ dressing, respectively). Com seeding on oat plant parts or on whole oat plants reduced corn emergente, com dry matter at 15 days after emergency (DAE), and corn height at 15 and 28 DAE. The best results for dry matter and height of com plants at 15 and 28 DAE were obtained with 60/60 kg/ha of N, as averages of all cover systems. For the variables com height at harvesting, leal area, and grain yield there were no differences between nitrogen fertilizer systems, with best results obtained with nitrogen application, as compared to the treatment without nitrogen. It is concluded that the presence of different oat plant parts decrease inicial development of corn plants, but do not reduce grain yield when the crop receives nitrogen.