Soil and Nutrient Losses in a Flat Land-Reclamation District of Central Italy

Erosion and nutrient losses represent two of the most important environmental impacts of agriculture. In a field experiment, we compared the impact and productivity of three continuous maize-cropping systems-conventional, low input and environmentally protective-on two contrasting soils (peat and loam soil) within a flat land-reclamation district of Central Italy. This area is characterized by intensive agriculture and the presence of a receiving eutrophic lake. Cumulative runoff, sediment, dissolved and particulate nutrient losses were discontinuously measured over 2years by means of 2-m2 runoff traps. The effect of cropping systems on erosion was influenced by soil type. Conventional showed the highest losses on the loam soil and low input on the peat soil, whereas environmentally protective ensured the best soil protection at both sites. Simple linear regressions were used to quantify the contribution of anthropogenic and non-anthropogenic predictor variables. Runoff was not influenced by the rainfall (more than 75% of variability explained), and soil losses were significantly affected by type of cropping system (23-25% of variability explained). We estimated the magnitude of the erosion on an annual basis by multiple linear regression models. Soil losses were relatively low, remaining below 0·8Mgha-1y-1 at both sites, while dissolved N losses ranged from 0·54 to 1·29kgha-1y-1, and dissolved P losses ranged from 0·50 to 0·80kgha-1y-1 at both sites. These results pointed to the presence of other sources and pathways of contamination in the lake eutrophication process.