Results Regarding the Impact of Crop Rotation and Fertilisation on the Grain Yield and Some Plant Traits at Maize Cultivated on Sandy Soils in South Romania

The reduced production capacity of sandy soils is due to their low natural fertility, but it is determined also by the way the plants are cultivated, respectively the crop technology. Fertilization according to the results of the soil analysis without considering the crop needs and the crop rotation does not represent a specific way to increase soil fertility. Under the same natural conditions, any crop - for the maximum yielding potential - requires different fertilization conditions, designated via the previous crop (precursory or preprecursory). Substituting the positive effects of the crop rotation through increasing the rates of fertilizers does not represent a reliable way to ensure the sustainability of the agricultural system. This is due to the fact that the yielding potential of the cultivated plants is conditioned by a variety of environmental factors among which the crop rotation is one of the most important. This influence is ever more significant under the less favorable growing conditions of the sandy soils. Under these circumstances, maize requires a specific crop technology, within which an important role is played by the crop rotation as well as the efficient use of fertilizers. The conducted researches, through the obtained results have shown that on the improved sandy soils from the Southern Romanian region Oltenia, the grain yield of maize cultivated in crop rotations is higher that the grain yield obtained in conditions of monoculture. Also, using nitrogen and phosphorus chemical fertilizers on the improved sandy soils represents a reliable measure to increase maize yield. The combined influence of the studied factors (crop rotation x fertilizers) has determined an even increased yield. For the exploitation of the improved sandy soils, it is essential to have a crop rotation with plants that improve soil fertility, such as annual leguminous and green fertilizers, as well as a crop rotation that makes the maximum use of chemical fertilizers.