Water runoff and soil erosion, registered in different crops, on 16% slope lands

English. The goal of the experiments carried out at the Podu-Iloaiei Agricultural Research Station, Iasi County, was the study of water runoff and soil losses, caused by erosion, in different crops and the influence of water and soil erosion on the losses of organic matter and mineral elements from soil. The results on water runoff and soil losses in different crops from the Moldavian Plateau have shown that in the last seven years, of the total amount of 608.4 mm rainfall, 387.5 mm (63.7%) produced water runoff, which was between 8.5 mm in perennial grasses, in the second year of vegetation, and 34.9 - 36.8 mm, in maize and sunflower crops. The annual soil losses due to erosion, recorded at the same period, were between 0.190 t/ha/year in perennial grasses, and 4.079 - 4.451 t/ha/year in maize and sunflower crops. Erosion has affected soil fertility by removing once with eroded soil, high amounts of organic carbon and mineral elements, which reached 10.71 - 11.26 kg/ha nitrogen, 0.56 _ 0.64 kg/ha phosphorus and 0.98 - 1.11 kg/ha potassium, in maize and sunflower crops. The crop structure, which determined the diminution in mean soil losses by erosion until 1.383 t/ha included 20% straw cereals, 20% annual legumes, 20% row crops and 40% perennial grasses and legumes. On land with a slope of 16%, lowering the percentage of weeding plants from 60% to 20% has reduced the amount of eroded soil by 49%.

Romanian; Moldavian; Moldovan. Experientele realizate la Statiunea de Cercetare- Dezvoltare Agricola Podu-Iloaiei, judetul Iasi, au urmarit studiul scurgerilor de apa si de sol prin eroziune, la diferite culturi, si influenta scurgerilor de apa si a eroziunii solului asupra substantei organice si a elementelor minerale din sol. Rezultatele obtinute privind scurgerile de apa si de sol prin eroziune, la diferite culturi, in Podisul Moldovei, arata ca, in ultimii sapte ani, din totalul de 608.4 mm precipitatii inregistrate, 387.5 mm (63.7%) au determinat scurgeri, care au fost cuprinse intre 8.5 mm la ierburile perene si 34.9-36.8 mm la culturile de porumb si floarea-soarelui. Pierderile anuale de sol prin eroziune au fost cuprinse intre 0.190 t/ha la ierburile perene si 4.079 _ 4.451 t/ha la porumb si floarea-soarelui. Eroziunea influenteaza fertilitatea solului prin indepartarea, odata cu solul erodat, a unor cantitati mari de elemente minerale care, la culturile de porumb si floarea-soarelui, ajung la 10.71 - 11.26 kg/ha azot, 0.56 _ 0.64 kg/ha fosfor si 0.98 _ 1.11 kg/ha potasiu. Structura culturilor, care a determinat reducerea pierderilor de sol prin eroziune sub 1.383 t/ha, a cuprins 20% cereale paioase, 20% leguminoase anuale, 20% culturi prasitoare si 40% leguminoase si graminee perene. Pe terenurile cu panta de 16%, scaderea procentului de plante prasitoare, de la 60% la 20%, a determinat reducerea cantitatilor de sol erodat cu 49%.