Properly spaced trees help provide many of the same benefits of a complete perennial cover. Fine soil particles contain most of the humus and nutrients in the soil, and if lost, soil fertility is reduced, while windbreaks help protect cropland by reducing wind velocities for a distance approximately 15 times the height of the tallest trees, thus providing significant reductions in the rate of soil loss over large areas. Establishing windbreaks is a practice that is highly suitable for degraded soils in the coastal regions of Viet Nam prone to water erosion and to the winds accompanying typhoons during the rainy season. Eucalyptus and cashew, the tree species that have been identified to break the cycle of land degradation, are also suitable for moderately saline soils.