Erosion-preventive crop rotations for landscape ecological stability in upland regions of Lithuania

摘要

A combination of perennial grass species and selected crop rotation can help prevent soil erosion in upland regions. Research data were obtained on sandy loam Dystric Albeluvisols at the Kaltinenai Research Station of the Lithuanian Institute of Agriculture on the undulating hilly topography of the Zemaiciai Uplands of Western Lithuania to identity crop and crop rotations that would minimise soil erosion. Measured water erosion rates during long-term field experiments were: 5.4-17.0 Mg ha(-1) under winter rye, 18.0-62.8 Mg ha(-1) under spring barley and 44.4-186.2 Mg ha(-1) under potatoes. Perennial grasses completely prevented water erosion. The erosion-preventive grass-grain crop rotations (>50% grass) decreased soil losses on arable slopes of 2-5degrees, 5-10degrees and 10-14degrees by 77-81%, while the grain-grass crop rotation (<50% grass) decreased rates by 21-24%, compared with the field crop rotation. The mean annual metabolisable energy accumulated by the erosion-preventive grass-grain crop rotations under optimum ground and fertiliser treatments on slopes of varying gradient was 96.7 GJ ha(-1). This was 24.8% higher than under the field crop rotation and 20.2% higher than under the grain-grass crop rotation. The mean digestible protein productivity of sod-forming perennial grasses was 13.1% higher than the mean productivity of grass-grain crop rotations and 53.7% higher than the grain-grass crop rotation on slopes of 10-14degrees. The erosion-preventive capability of crop rotations depends on their structure and composition. The grass-grain crop rotations and sod-forming perennial grasses significantly increased soil aggregate stability compared with grain-grass crop rotations on 10-14degrees slopes, thus both these systems decrease soil erodibility. The main attributes of the proposed land conservation and sustainable land-use system were the careful selection of optimum erosion-preventive ecosystems (sod-forming perennial grasses or erosion-preventive crop rotations) with high erosion-resisting capabilities. These systems must vary in response to slope conditions. Such ecosystems assist erosion control and thus the ecological stability of the undulating topography of Lithuania. These results may have wider applicability on the undulating landscapes of the Temperate Zone.