Ana Maria DODOCIOIU, Andreea Maria Nicolae, Stefan Popescu, Romulus MOCANU, Marian DOBRE
On slopes soils there take place important nutrient losses that inflict pollution of surfacewaters. The most lost nutrient is nitrogen yet the phosphorus from soluble fertilizers is also lost. Thesenutrients reach into surface waters where determine eutrophication phenomenon. In order to implementthe objectives of Water Frame Directive 2000/60/CE there have been searched methods for mitigation thenutrient pollution from slope soils. These methods are: - the using of organic – mineral fertilizers (L120)instead of soluble phosphorus fertilizers (superphosphates); - buffer strips at the bottom of the slope;-filtering materials for water from creeks. The applying of these methods have contributed to the reductionof the nutrient losses (nitrogen and phosphorus) from slope soils with values ranging between 38-41% byapplying organic – mineral fertilizer and by 52-64% when buffer strips were installed. The using of strawballots as filtering materials for creek water has determined the reduction of nutrient losses by 72%. Thisway, the using of organic – mineral fertilizer on lignite base (L-120) has determined the diminishing ofphosphorus losses on slope soils due to bonding phosphorus from this fertilizer in an organic – mineralmatrix that speeds up the retrogradation and solubilisation processes of phosphorus. The using of grassbuffer strips of 10 m wide on level curves at the bottom of the slope along Preajba creek has determinedan obvious decreasing of the eroded soil quantity, of humus and nutrient losses due to better retention byroot system and its higher density. Straw ballots across the course of a creek are a good filter for runningwaters. The straw action is similar with soil colloidal complex, they retain chemical ions from water like:NO3, NH4, K, PO4, etc. By using straw ballots there can be avoided the eutrophication phenomenon ofthe surface waters. The using of crops like natural and sown pasture as well as cereals could be a methodto mitigate nutrient losses on slopes. Wide row crops should be avoided as much as possible.
slope, nutrient losses, Water Frame Directive, nitrogen, phosphorus
Presentation: oral