THE ESENTIAL ROLE OF CROP ROTATION AND NITROGEN FERTILIZATION IN WHEAT AND MAIZE IN THE SUSTENABLE AGRICULTURE SYSTEM OF REDDISH PRELUVOSOIL

Research presents the results of the study object Agrotechnics performed between 1996 and 2010 on the reddish preluvosoil crop rotation field of Moara Domnească, the Romanian Plain, belonging to the Faculty of Agriculture, USAMV – Bucharest. The experiment was bifactorial, organised according to the split method, in four replications, with factor A being the rotation and factor B – fertilization with mineral nitrogen. Factor A – rotation –contained six rotations with the following graduations: a1 – wheat monoculture, a2 – maize monoculture, a3 –two-year rotation: 1. wheat, 2. maize, a4 –three-year rotation: 1. soybean, 2. wheat, 3. maize, a5 –four-year rotation: 1. peas, 2. wheat, 3. sugar beat, 4. maize, a6 – 1. sunflower, 2. wheat, 3. maize, 4. wheat/alfalfa. Factor B – fertilizing with mineral nitrogen, had the following graduations: b1 – unfertilised, b2 – N50, b3 - N100, b4 – N150. The following factors influencing the yield were discussed: the associated influence of crop rotation and fertilization with mineral nitrogen; the influence of the organic material amount in the soil, weed biomass, the content and the quantity of raw protein in wheat and maize. Under the influence of crop rotation, weeding reduction was achieved both in wheat and maize. The association of rotation with fertilization determined an increase in organic biomass, with an amplified action of the factors in maize. In wheat, the highest production was achieved in the three-year and four-year crop rotations, while in maize the maximum yield was achieved in the three-year crop rotation, four-year crop rotation and four-year crop rotation with jumping plot rotation after wheat.