اثر مدیریت خاکورزی و محصول بر فرسایش خاک در مرکز کرواسی

Soil erosion continues to be a primary cause for soil degradation and the loss of soil quality throughout the world. Our objectives were to quantify soil erosion (referred to as erosional drift) and to assign erosion risk to six tillage and crop management treatments evaluated from 1995 to 1999 for a 5-year maize (Zea mays L.), soybean (Glycine hyspida L.), winter wheat (Triticum aestivum L.), oil-seed rape (Brassica napus var. oleifera L.), and spring barley (Hordeum vulgare L.) plus double-crop soybean rotation on Stagnic Luvisols in central Croatia. Standard black fallow (tilled, unsown, and without any vegetative cover) Universal Soil Loss Equation (USLE) plots were used to establish the erosion potential associated with the rainfall pattern for each year. Soil loss from the check plots was several times greater than the T value, which is estimated to be 10 t ha−1 per year. During the 2 years when spring seeded maize or soybean were grown (1995 and 1996) erosion risk was extremely high, especially for treatments where tillage and planting (row direction) were up and down the slope. When autumn seeded winter wheat or oil-seed rape were grown (1996/1997 or 1997/1998), soil erosion was insignificant. Also, except when plowing and sowing were up and down slope, erosion loss for the spring barley plus double-crop soybean crops in 1999 was insignificant. With no-tillage, soil erosion from the maize and soybean crops was reduced 40 and 65% compared to plowing up and down slope, even though the planting direction was still up and down the slope. With the exception of maize in 1995, erosion losses were moderate to insignificant when plowing and planting were performed across the slope. We conclude that erosion risk can be used as a reliable indicator of sustainable land management and that using no-tillage or plowing and planting perpendicular to the predominant slope are effective soil conservation practices for this region.

Water induced soil erosion is influenced by tillage (especially the plowing direction in relation to slope), crop selection, planting direction or orientation, and the amount, distribution, and intensity of rainfall or irrigation. Quantifying and understanding the factors influencing soil erosion is especially important with regard to the soil quality and sustainability of Stagnic Luvisols in central Croatia. The physical composition (e.g. high content of fine sand), chemical properties (e.g. low pH value, calcium carbonate deficiency, low organic matter content), and very low aggregate stability make those soils highly susceptible to water erosion on sloping terrains (Richter, 1980, Le Bissonais et al., 1995, Kwaad et al., 1998, Rejman et al., 1998 and Fleige and Horn, 2000). The primary goals for this investigation were to determine how various tillage and cropping practices affected soil erosion in this region and to use those results to identify sustainable land management practices that would reduce soil erosion to a tolerable level. Working within an established crop rotation, we measured soil loss using standard Universal Soil Loss Equation (USLE) plots and identified the optimum tillage and crop management practices in terms of erosion risk. The results provide a scientific basis for sustainable management of Stagnic Luvisols in central Croatia and for other soils in similar agroecological zones throughout the world.

Sustainable management of sloping arable land in central Europe requires tillage and crop management practices that minimize soil erosion. The results of our 5-year investigation show that erosion risk can be used as a reliable indicator of sustainability for highly erosive Stagnic Luvisols. Using standard USLE plots, we demonstrated for the check (SBF) or bare soil treatment that potential erosion was several times higher than the current T value (10 Mg ha−1 per year). The combination of subsoiling followed by plowing and planting across the slope (SSPAS) was most effective for reducing soil erosion, but is currently too expensive to implement. Furthermore, because the soils already have a low organic matter concentration, improving soil quality with an intensive tillage regime will be very difficult. No-tillage (even with an up and down slope row orientation) and all across the slope plowing and planting treatments achieved efficient soil conservation on the Stagnic Luvisols in this study. Soil erosion for all crops grown was below the tolerance or T value for the NT, PAS, VDPAS, and SSPAS treatments. Our study also showed that growing spring row crops (i.e. maize and soybean) resulted in higher erosional drift (soil loss) than high-density winter crops (wheat and oil-seed rape) or a double-crop combination of spring barley followed immediately after harvest by soybean. Growing maize and soybean on sloping terrains in central Croatia and similar central European locations will require an appropriate tillage and crop management system to ensure the soil and water resources are sustained.