Long-term effects of cropping system and mineral fertilization on production and soil fertility in the Moldavian Plain

English. The investigations conducted during 2005-2010 at the Podu- Iloaiei Agricultural Research Station, Iasi county, have studied the influence of different mineral fertilizers rates on wheat and sunflower yield and soil agrochemical characteristics. In bean-wheat-maize-sunflower-wheat crop rotation, applying mineral fertilizers resulted in getting mean yield increases, which varied according to rates, between 94 and 180% (1631-3129 kg/ha) in wheat and between 38 and 101% (773-2063 kg/ha) in sunflower. The mean yield increases, obtained for each kg of a.i. of applied fertilizer, were comprised between 11.2 and 13.6 kg grains (N80P40 - N160P80) in wheat and between 9.2 and 9.7 kg grains (N40P40 - N120P80) in sunflower. In the soils from the Moldavian Plateau, which are poor in organic matter and nutrients, the proper use of different rotations and fertilizer doses may replace a part of high technological consumption, determined the improvement in the content of organic matter from soil and ensured better conditions for the capitalization of nitrogen fertilizers. On the Cambic Chernozem from the Moldavian Plateau, a good supply with mobile phosphorus in wheat and sunflower crops (37-72 mg/kg) was done in case of the annual application of a rate of N120P80, while a very good supply (72-91 mg/kg) was achieved at the rate of N140P100. After 44 years of experiences, in five year crop rotation, fertilization of sunflower, wheat and maize crops with high rates of mineral fertilizers (N160P80), resulted increased soil organic carbon content by 22,7% (3.5 g C / kg soil), compared to the unfertilized control.

Romanian; Moldavian; Moldovan. Cercetarile efectuate, in perioada 2005-2010, la Statiunea de Cercetare-Dezvoltare Agricola Podu-Iloaiei, jud. Iasi, au urmarit influenta diferitelor doze de ingrasaminte minerale asupra productiei de grau si floarea-soarelui si a insusirilor fizice si chimice ale solului. In rotatia fasole-grau-porumb-floarea-soarelui-grau, aplicarea ingrasamintelor minerale a determinat obtinerea unor sporuri medii de productie, care au variat in functie de dozele aplicate, intre 94 si 180% (1631- 3129 kg/ha) la grau si intre 38 si 101% la (773-2063 kg/ha) floarea-soarelui. Sporurile medii de productie, obtinute pentru fiecare kg s.a. de ingrasamint aplicat, au fost cuprinse intre 11,2 si 13,6 kg boabe la grau (N80P40 - N160P80) si intre 9,2 si 9,7 kg la floarea-soarelui. Pe solurile din Podisul Moldovei, care sunt sarace in substante organice si elemente nutritive, folosirea adecvata a diferitelor rotatii si doze de ingrasaminte poate inlocui o parte din consumul tehnologic ridicat, poate determina imbunatatirea continutului de substante organice din sol si asigura conditii mai bune de valorificare a ingrasamintelor cu azot. Pe solul de tip cernoziom cambic din Podisul Moldovei, o asigurare buna cu fosfor mobil la culturile de grau si floarea-soarelui (37-72 mg/kg) a fost realizata prin aplicarea anuala a unei doze de N120P80, iar o asigurare foarte buna (72-91 mg/kg) a fost realizata la doza de N140P100. Dupa 44 de ani de experimentare, in rotatia de cinci ani, fertilizarea culturilor de floarea-soarelui, grau si porumb cu doze mari de ingrasaminte minerale (N160P80) a determinat, comparativ cu martorul nefertilizat, cresterea continutului de carbon organic din sol cu 22,7% (3.5 g C/kg sol).