Corn Yield Induced by the Amount and Quality of Winter Crops Residue in No Tillage System.

In no tillage system, the plant residues of untilled crops form a nutrient reserve. Therefore, the amount and quality of plant residues are related to the no-tillage efficiency, which reinforces the importance of an appropriate crop rotation system. Additionally, climate adaptation is highly important when choosing the species for a crop system. The purpose of this study was to evaluate the influence of winter crops dry matter production and nutrient accumulation on corn yield in no tillage system. The experiment was conducted during the 2008/2009 growing season at Jaboticabal, SP, Brazil (21°14′S, 48°17′W and altitude of 550 m). Climatologically the area belongs to tropical/megathermal zone or Köppen’s Aw. The mean annual rainfall is 1417 mm, with an annual distribution peaking in the period of October to March and a relatively dry season in the period of April to September. The soil of the experimental area is a Rhodic Eutrudox. In the 0-20 cm layer, the mean contents of clay silt and sand is 555, 63 and 381 g kg^‑1, respectively. The statistical design used was randomized block with three replications. The treatments consisted of seven winter crops, sowed in February-March: corn, sunflower, oilseed radish, pearl millet, pigeon pea, grain sorghum and sunn hemp. Corn, sunflower and sorghum were grown until grain harvest. Oilseed radish, millet, pigeon pea and sunn hemp were cut at flowering, using a shredder. The highest corn yields were obtained after sunn hemp and millet, probably, due to the higher N, P and S accumulated in his shoots. The corn yield correlated positively with winter crops dry matter production and N, P and S accumulation.