The influence of agriculture activity on the soil quality and productivity

The soil is not only a target to be used for agricultural purposes, but it is also the component of the ecosystems. One of the main tasks in today agricultural science - to preserve the fertile and clean soil as the main part of.the ecosystem as well as healthy environment for people. The long-term fertilization trials have been carried out since 1966 in the Experimental station of the Aleksandas Stulginskis University on light sandy loam over moraine clay Calc(ar)i-Epihypogleyic Luvisols. In the 4-year crop rotation winter wheat (Triticum aestivum), beetroot {Beta vulgaris), spring barely (Hordeum vulgare) with perennial grasses (Trifolium pratense and Phleum pratense) were cultivated. Organic fertilizers (farming manure 50 and 1001 ha-1) were applied once per rotation during the beetroot growth. In the system per rotation the averages rates of the mineral fertilization (N31P3gK75 and N?9P65K90) was used, though, in the organic-mineral fertilization the combined application of manure (50 t ha1) with the mineral fertilizers (N3JP3gK75) was done. Composite soil sampling in three field replicates (n=3) for evaluation of the chemical properties were taken in each investigated treatment in spring in 2006, 2007 and 2008 before the fertilisation, and after the harvesting for the evaluation of soil physical properties in the arable Ap horizon of 0-20 cm depth layer. To summarise the soil physical properties results it could be concluded that, along the long-term fertilisation, particularly applying the organic and organic-mineral (with NPK fertilization at the lowest dose) fertilisers, the soil bulk density was decreasing and have remained optimal (1.38-1.39 Mg m~3), there were no consistent changes in soil porosity, as the quantity of the stable aggregates was increasing. While applying the mineral fertilisation system, the bulk density was the highest (1.40-1.42 Mg m~3)Vytauto Didžiojo universitetasŽemės ūkio akademij