Through the experience realized at SCDA Caracal we have followed the effect of different doses of chemical fertilizers on the production of wheat, and especially on the evolution of nitric nitrogen at the surface of the soil (0 – 20 cm), which can bring about in drought conditions – phenomenon frequent in this area, big accumulations and pollution of the wheat crop. Many researches took place in our country and abroad concerning the influence of fertilizer doses, of nitrogen dynamics in the soil and the soil tillage on the wheat crop; they highlight a series of important aspects generated by the conditions of experimentation and the possibility of using some different machines for the basic soil tillage. When choosing the area for the experiment we have taken into account the suitability of cambic baticalcaric chernozem for the wheat culture. The problem of soil pollution with nitrates is a current issue for this area because the natural climate conditions, the lack of irrigation water (necessary for this culture) doesn`t permit the nitrogen to migrate on the soil profile, but to remain in large quantities at its surface bringing about some harmful effects for the plants. In order to conserve water in the soil during the vegetation period, we have considered that it is necessary to use the chisel plough (18 – 20 cm). In our country, the prognosis of the effect of nitrogen fertilizers is different function of the soil (through specific items of nitrogen regime), function of the plant (with a specificity of nitrogen consumption), function of the nature and type of fertilizer, the method and technology of application and other important factors for the nitrogen circle. The crops use nitrogen as NO3-, because the ammonium ions from the soil are quickly oxidized to NO3- through the action of microorganisms. The study of nitrogen dynamics from the soil for different phases of wheat crop gives us clues on the moment we can intervene in the nourishing with nitrogen of this crop and the necessary doses, so that the crops can be economically justified. The dynamics of nitric nitrogen from the soil was made through the determination of this form of assimilable nitrogen for different dates during the vegetation period for the wheat culture, when we have taken soil probes, at the depth of 0-20 cm. We have obtained different values of nitric nitrogen in the soil, (4,46 ppm and 49,61 ppm) function of the doses of nitrogen. Theoretically, the chisel plough assures a suitable aeration corresponding the good development of nitrification process, with direct implications on the production that will be obtained. Because the fertilization is the main factor in obtaining high productions for any crop we have administrated different doses of nitrogen, between N0 and N150 kg/ha on a constant fund of P80, and the productions were between 1317 kg/ha and 6403 kg/ha. The data obtained from this experiment will be useful for wheat cultivators in the south Romania, but also other area having the same problems regarding drought, because this experience aims at conserving water in the soil through a different soil tillage.

nitric nitrogen; wheat crop; fertilizers; chisel

Presentation: oral