Effectiveness of pine roots on elements transport of loess soil during the heavy rainstorm on the Chinese Loess Plateau

Plant roots are the main interface for plants to uptake nutrients from soil and may have potential impacts to intensify elements transport in the loess soil.Climate,especially rainfall is the main factor for soil formation and soil environment.To assess the effectiveness of plant roots on elements transport of loess soil during the heavy rainstorm,a field study was carried out on nutrients transport in the forest(Pinus tabulaeformis) soil as affected by pine roots and farmland soil with no roots as the control on the hilly and gully areas of the Loess Plateau.With the method of a large-size profile for measuring root density and root weight and an equipment of undisturbed monolith soil for measuring elements transport of loess soil,we investigated transport flux of 9 elements in the loess soil during the rainfall of 200 mm and rain intensity of 2.0 mm/min.The objective was to establish the effective model of plant root for intensifying elements transport flux in the loess soil,in order to provide a scientific foundation for improving the nutrients uptake of plant roots and establishing the fine artificial ecological systems of soil and water conservation.The results indicated that differences among elements transport flux in the loess soil during the heavy rainstorm were not only depended on the amount of elements in soil but mainly on the distribution of plant roots less than 1 mm in diameters.Impacts of plant roots on intensifying elements transport in the different depth of the loess soil decreased as the soil depth increased.As for the pine-land during the heavy rainstorm,elements output flux in the soil layer of 060 cm decreased significantly with the increase of the soil depth;as for the farmland,there are no significant differences for the whole soil profile.The impacts on the transport flux of K,Na,Mg,Ca,Si,Mn tended sharply to lighter in the soil layer of 030 cm,but its impacts on the transport flux of Al,Cu,Fe approached sharply to smaller in the soil layer of 045 cm in the pine-land during the heavy rainstorm as the increase of soil depth.The effective root parameters had significant positive relationship with the impacts of plant roots to intensify elements transport in soil profiles on the Loess Plateau with the R~2 between 0.95 and 0.99.