Analysis of soil Ca, Mg, Al saturation (m%) and dry mass of cover crops under crop rotation

No-tillage system is an alternative agricultural management to protect soil; however, the cover crops association is required in crop rotation or succession, allowing an amount of nutrients supply and organic matter to soil through mineralization of plant residues. Thus, this trial aimed at evaluating the effects of crops succession on soybean yield and on chemical properties of soil: calcium, magnesium and aluminium saturation (m%). The trial was carried out in Cafelândia (PR) city, in a typical eutrophic red latosol, from June 2008 to March 2010. The experimental design was completely randomized with five treatments: black oat; consortium 1 (turnip and black oat); consortium 2 (turnip, black oat and common vetch), wheat and fallow, with six replications in a 2 ha area, in four periods during two agricultural harvests, in order to record chemical analyses of soil in a depth from 0 to 0.2 m. The cover crops management was with roll-knife, while wheat was harvested with an automotive combine. Soybean was sown in summer and its yield was determined for each treatment. Winter cover crops influenced on Mg concentration in soil when evaluated after soybean harvest in 2010, so that, black oat and the second consortium were the main responsible for such increase, although, the treatments showed no effect on soybean yield during the 2009/2010 harvest.