Abstract
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.
Highlights
In the no tillage system, the rotation of crops with species that increase plant residues on soil surface is fundamental to avoid erosion and to improve nutrient cycling through nutrient mobilization from deeper soil layers (Crusciol et al, 2005) to the top
Summer soybean/maize rotation and maize monoculture resulted in lower organic matter contents and P levels in the layers 0–10 cm and 0–20 cm, respectively
Summer rice/bean/cotton rotation increased soil K levels at depth 0–10 cm when sunn hemp and oilseed radish were previously grown in the winter, and at 0–2.5 cm for millet cropping
Summary
In the no tillage system, the rotation of crops with species that increase plant residues on soil surface is fundamental to avoid erosion and to improve nutrient cycling through nutrient mobilization from deeper soil layers (Crusciol et al, 2005) to the top. The amount and quality of plant residues are related to how long they persist on the soil surface and determine the no-tillage efficiency, which reinforces the importance of an appropriate crop rotation system (Torres et al, 2005). Climate adaptation is highly important when choosing the species for a crop system (Ceretta et al, 2002). Other desirable characteristics, such as high dry matter production, fast establishment and easy management, as well as a deep and vigorous root system are required. The interest of producers in market prospects for sales must be taken into account
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