The Effects of Erosion and Desurfacing on Soil Properties and Productivity of a Typic Haplustoll

Topsoil is a valuable resource to humankind. Current food production cannot be continued without this resource. Topsoil protection efforts must be continued or increased to meet future demands of mankind. Erosion reduces productivity but losses may not be detected until land is no longer suitable to produce crops economically, furthermore, other variables may mask the relationship. Technology advancement including improved seed varieties, modern fertilizer, and herbicide have doubled or tripled many North American crop yields in the past 50 years. The impact of topsoil removal is largely determined by subsoil properties as they affect root growth, soil available water and nutrient availability in the soil. A new soil environment is encountered when topsoil is removed either by natural or artificial erosion. This new environment in most cases is less suited for plant growth than original topsoil. Germination and emergence are often poor because of less than ideal soil physical properties. Topsoil loss may alter root system growth. The potential for nutrient and water uptake consequently depends on the new level of soil nutrients and available water surrounding the root system, and the morphology of the root system. Topsoil removal may change resistance of surface aggregates to the beating action of raindrops. The stability of surface aggregates is important because aggregates below the surface are protected from rapid wetting by those above. Unstable surface aggregates are easily broken down and transported in suspension. This can lead to the formation of crusts that inhibit the movement of water and air into the soil. Maridasan and Chibber obtained a significant negative correlation between aggregate stability and the erosion ratio. Furthermore, aggregate stability influences plant growth indirectly through its relationship to the maintenance of a porosity suitable for air, water, and root movement. Recently, researchers have devoted considerable effort to quantify the relationship between topsoil removal and soil productivity, principally on the basis of data from the North Central Region of the United States. The objectives of this study were: (1) to determine the effects of erosion and desurfacing on soil physical and chemical properties. (2) to examine the relationships of aggregate stability (a measure of soil structural stability) with soil properties which result from the erosion and desurfacing of a Beadle Tax adjunct (Fine, montmorillonitic, mesic Typic Haplustoll). (3) to assess and compare the effect of erosion and desurfacing on continuous corn yield for this soil in eastern South Dakota

Sorption of Tannin and Related Phenolic Compounds and Effects on Extraction of Soluble-N in Soil Amended with Several Carbon Sources

Some tannins sorb to soil and reduce soluble-N. However, we know little about how they interact with organic amendments in soil. Soil (0–5 cm) from plots, which were amended annually with various carbon substances, was treated with water (control) or solutions containing tannins or related phenolic subunits. Treatments included a proanthocyanidin, catechin, tannic acid, β-1,2,3,4,6-penta-O-galloyl-D-glucose (PGG), gallic acid, and methyl gallate. We applied solutions of each of these materials to soil and measured soluble-C and -N in supernatants after application and following extraction with hot water (16 h, 80 °C). Sorption was low for non-tannin phenolics, methyl gallate, gallic acid, and catechin, and unaffected by amendment. Sorption of tannins, proanthocyanidin, tannic acid, and PGG, was higher and greater in plots amended with biosolids or manure. Extraction of soluble-N was not affected by amendment or by catechin, proanthocyanidin, or methyl gallate, but was reduced with PGG, tannic acid and gallic acid. Soil cation exchange capacity increased following treatment with PGG but decreased with gallic acid, irrespective of amendment. Tannins entering soil may thus influence soil organic matter dynamics and nutrient cycling but their impact may be influenced by the composition of soil organic matter