Investigations on the influence of fertilization system and erosion on wheat yield and on some soil agrochemical characteristics

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.