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Decomposing crop residues in no-tillage system can alter soil chemical properties, which may consequently influence the productivity of succession crops. The objective of this study was to evaluate soil chemical properties and soybean, maize and rice yield, grown in the summer, after winter crops in a no-tillage system. The experiment was carried out in Jaboticabal, SP, Brazil (21 ° 15 ' 22 '' S; 48 ° 18 ' 58 '' W) on a Red Latosol (Oxisol), in a completely randomized block design, in strip plots with three replications. The treatments consisted of four summer crop sequences (maize monocrop, soybean monocrop, soybean/maize rotation and rice/bean/cotton rotation) combined with seven winter crops (maize, sunflower, oilseed radish, pearl millet, pigeon pea, grain sorghum and sunn hemp). The experiment began in September 2002. After the winter crops in the 2005/2006 growing season and before the sowing of summer crops in the 2006/2007 season, soil samples were collected in the layers 0-2.5; 2.5-5.0; 5-10; 10-20; and 20-30 cm. Organic matter, pH, P, K+, Ca2+, Mg2+, and H + Al were determined in each soil sample. In the summer soybean/maize rotation and in maize the organic matter contents and P levels were lower, in the layers 0-10 cm and 0-20 cm, respectively. Summer rice/bean/cotton rotation increased soil K levels at 0-10 cm depth when sunn hemp and oilseed radish had previously been grown in the winter, and in the 0-2.5 cm layer for millet. Sunn hemp, millet, oilseed radish and sorghum grown in the winter increased organic matter contents in the soil down to 30 cm. Higher P levels were found at the depths 0-2.5 cm and 0-5 cm, respectively, when sunn hemp and oilseed radish were grown in the winter. Highest grain yields for soybean in monoculture were obtained in succession to winter oilseed radish and sunn hemp and in rotation with maize, after oilseed radish, sunn hemp and millet. Maize yields were highest in succession to winter oilseed radish, millet and pigeon pea. Rice yields were lowest when grown after sorghum.

RESUMO

summaRyBecause of the climate changes occurring across the planet, especially global warming, the different forms of agricultural soil use have attracted researchers´ attention. changes in soil management may influence soil respiration and, consequently, c sequestration. the objectives of this study were to evaluate the long-term influence of liming on soil respiration and correlate it with soil chemical properties after two years of liming in a no-tillage system. a randomized complete block design was used with six replications. the experimental treatments consisted of four lime rates and a control treatment without lime. two years after liming, soil co 2 emission was measured and the soil sampled (layers 0-5, 5-10, 10-20, and 20-30 cm). the p, ca 2+ e mg 2+ soil contents and ph and base saturation were determined. co 2 emission from soil limed at the recommended rate was 24.1 % higher, and at twice the recommended rate, 47.4 % higher than from unlimed soil. liming improved the chemical properties, and the linear increase in soil respiration rate correlated positively with the p, ca 2+ and mg 2+ soil contents, ph and base saturation, and negatively with h + al and al 3+ contents. the correlation coefficient between soil respiration rate and chemical properties was highest in the 10-20 cm layer.Index terms: soil co 2 emission, limestone, soil fertility.(1) Received for publication in march 3, 2011 and approved in october 8, 2011. (2) 0-5, 5-10, 10-20 e 20-30