Abstract:
By diminishing soil fertility, the erosion process
determined the differentiation of mean wheat yield according to slope and
erosion, from 3905 (100%) to 3078 kg/ha (78.8%). The mean annual losses
of yield registered in wheat in the last 10 years, caused by erosion, were of
827 kg/ha (21.2%). The humus and nutrient content from soil was
maintained at a supply level proper to the requirements of plant nutrition,
only under 3 or 4 year rotation, and in case of annual use of rates of at least
100 kg N + 100 kg P2O5 or mean rates of mineral elements with 60 t/ha
manure. The use of mineral fertilizers with manure resulted in increasing
mobile phosphorus content from soil until 94 ppm, achieving a good and
very good supply in mobile phosphorus and increasing humus content from
soil to 4.18%. On weakly and highly eroded soils, the application of
moderate rates of mineral fertilizers with 3 t/ha pea stalks determined the
improvement in soil ureasic and phosphatasic potential, ensuring a better
plant supply with assimilate phosphorus. The use of manure or residues,
which are easily degradable with mean rates of mineral elements, resulted
in achieving soil nutrient supply and biological characteristics very close to
those obtained by using high rates of mineral fertilizers. On slope lands,
poor in organic matter and mineral elements, establishing the best fertilizer
rates, which ensure crop consumption and maintain good soil supply in
mineral elements, is more difficult, especially in crops requiring high
amounts of mineral elements, as wheat and maize.
