科研之友
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摘要
the objective of this study, which employed a randomized complete block design, with four replicates, was to evaluate, after eight years (1995 to 2003), the soil fertility of a typical dystrophic red latosol (typic hapludox) located in coxilha, rio grande do sul state, brazil, in six crop-livestock production systems (ilp): i) wheat/soybean, black oats common vetch pasture/corn; ii) wheat/soybean, black oat common vetch ryegrass pasture/corn; iii) wheat/soybean, black oat common vetch pasture/pearl millet pasture; iv) wheat/soybean, black oat common vetch ryegrass pasture/pearl millet pasture; v) wheat/soybean, oats/soybean, and black oat common vetch pasture/pearl millet pasture; and vi) wheat/soybean, oats/soybean, and black oat common vetch ryegrass pasture/pearl millet pasture). soil core samples were also collected in a fragment of subtropical forest adjacent to the experiment. after eight years, acidification in the top soil layer was observed. the exchangeable mg and k and extractable p were affected by mixed-crop production models. the soil layers of 0-5 and 5-10 cm presented higher values of soil organic matter, p, and k. the reverse occurred with values of ph and exchangeable al. the levels of soil organic matter, p, k and ca mg decreased with soil depth. the crop systems studied presented higher values of c in the soil than the subtropical forest.
