LA FUMURE AZOTEE DU MAÏS EN RELATION AVEC L’ESPACEMENT DES RANGS

Nine field trials were made with corn (Zea mays L.) on six Quebec soils during 1971–1973. Three nitrogen levels (100, 200 and 300 kg N/ha) were combined with three-row spacings (46, 61 and 76 cm). The effect of nitrogen varied greatly from year to year among the sites, and it was likely due to soil and rainfall effects, because the latter varied greatly during the three trial seasons. However, nitrogen applications were beneficial in seven trials out of nine, particularly so on the Rideau clay during a rainy season. Yields were doubled and reached 10,284 kg/ha on two sites in 1972. Total crude protein production was tripled compared to the control treatment on Rideau clay and reached 1,000 kg/ha in 1971 and 1972. Also, a 1,000-kg/ha crude protein production was achieved on Bedford clay site near Quebec City in 1972. Beneficial effects attributable to row spacings were found with four trials out of nine, and its effects seem to be independent of nitrogen rates. Although mean corn yields appear to be highest with the 46-cm row spacing, it was nevertheless decided that a 61-cm row width, with a plant population of 80,000–100,000 plants/ha should be generally recommended because of uneven response to row spacing caused by climatic, soil and cultivar effects. Nitrogen rates of 100 kg N/ha should suffice, though under adverse conditions, rates of 200–225 kg N/ha are required to reach maximum production.