Upland nitrogen

Campbell, J. L., J. W. Hornbeck, W. H. McDowell, D. C. Buso, J. B. Shanley, and G. E. Likens. 2000. Dissolved organic nitrogen budgets for upland forested ecosystems in New England. Biogeochemistry 49 123-142. 

Figure 10.1 Schematic of nitrogen sources and cycling in estuaries. These sources range from a diverse group of both diffuse non-point agricultural, urban, and rural point sources (e.g., wastewater, industrial discharges, stormwater, and overflow discharges) across a broad spectrum of watersheds (e.g., urban, agricultural, upland and lowland forests). (Modified from Paerl et al., 2002.)...

Upland surface water may be very good, provided the sources are free from habitation. Vegetable organic matter is present, sometimes in large quantity, so much so that the water may possess a decided yellowish-brown tint. Animal matter will be absent, so that the nitrogen content should be low, any ammonia, nitrates, or nitrites present being in such amounts as are contained in rain water. Chlorides are low and, unless the soil is calcareous, the water is soft. 

Howes, B., Weiskel, P., Goehringer, D., and Teal, J. (1996). Interception of freshwater and nitrogen transport form uplands to coastal waters The role of saltmarshes. In Estuarine Shores Evolution, Environments and Human Alterations (Nordstrom, K., and Roman, C. T., eds.). Wiley, New York. pp. 287—310. 

Discnss the biogeochemical cycle of nitrogen in mixed ecosystems. Stress your attention on wetlands and upland landscapes. 

TABLE 2 Contrasts in Aboveground Net Primary Production (ANPP), Soil Physical Properties, Organic Carbon and Total Nitrogen Pools (0- to 10-cni depth), and Fluxes in Soils Associated with Woody Plant and Grazed Grassland Communities in a Sandy Loam Upland Landscape at the La Copita Research Area in Southern Texas... 

Livingstone, D., Pentecost, A. and Whitton, B.A. (1984) Diel variations in nitrogen and carbon dioxide fixation by the blue-green alga Rivularia in an upland stream. Phycologia 23, 125-133. 

Turner, B.L., Chudek, J.A., Whitton, B.A. and Baxter, R. (2003c) Phosphorus composition of upland soils polluted by long-term atmospheric nitrogen deposition. Biogeochemistry 65, 259-274. 

Turner, B.L., Chudek, J.A., Whitton, B.A. and Baxter, R. (2003b) Phosphorus composition of upland soils polluted by long-term atmospheric nitrogen deposition. Biogeochemistry 65, 259-274. Turner, B.L., Driessen, J.P., Haygarth, P.M. and Mc-Kelvie, I.D. (2003c) Potential contribution of lysed bacterial cells to phosphorus solubilisation in rewetted Australian pasture soils. Soil Biology and Biochemistry 35, 187-1 89. 

Fungi, which are active in upland environments, cease to exist in wetland soils. This is primarily due to the absence of oxygen and alteration in soil pH (acid to neutral) under anaerobic conditions. Overall, microbial biomass decreases under saturated soil conditions. The metabolic activities of anaerobic bacteria depend on alternate electron acceptors, such as oxidized forms of nitrogen, iron, manganese, and sulfur. Under wetland soil conditions, rates of many microbially mediated reactions decline, and some reactions may be eliminated and replaced by new ones. New microbial reactions are involved in the reduction of oxidized compounds during respiratory processes, resulting in the production of reduced compounds. 

Typically, phosphorus is added in various forms to a watershed (Figure 9.1). These include fertilizers, nonhazardous wastes (animal manures and biosolids), and nutrient-enriched waters. Historically, organic wastes such as animal manures were applied to agronomic crops and pastures on the basis of the nitrogen availability, which has resulted in excessive application of phosphorus. As a result, many uplands used for land application of wastes have accumulated phosphorus in excess amounts. A major portion of the phosphorus added to uplands is retained within the soil. However, as upland soils become saturated or overloaded with phosphorus, a significant portion of the stored phosphorus can be released and transported with water during runoff events. 

Wetlands and aquatic systems are recipients of phosphorus loads from upland systems. Increased loading of phosphorus to a system can cause nitrogen limitations. The phosphorus enrichment of P-limited systems leads to eutrophication and ecosystem stress. The phosphorus cycle does not have a significant gaseous loss mechanism. Thus, most of the added P accumulates in the systems. 

Upland game birds (14) Inorganic carbon (22) Inorganic nitrogen (25)... 

Continuous study of oxyacetamide chemistry shifted research from the paddy herbicide to an upland herbicide with increasing water solubility that is suitable for such upland use. To this end, benzanellated analogues such as the benzothia-zole moiety of mefenacet were changed to simple five-membered heterocycles that contain at least one nitrogen atom to increase water solubility, and sulfur or oxygen atom to decrease lipophilicity, for instance thiazoles, thiadiazoles, oxazoles and oxadiazoles (Fig. 8.2). Consequently, many patent applications of the new class of heteroxyacetamide herbicides were disclosed [17, 18]. 

Acid rain has been shown to be derived from the release of oxides of sulphur and nitrogen from the combustion of fossil fuels (oil, coal and gas), the principal cause being power production. It is a major problem in Europe and eastern and northern America where the acidity of rainfall is enhanced by the water solubility of these gases. Certain upland regions have soils with a low capacity for the neutralization of an enhanced acidity and... 

A more recent approach in plant diagnostic techniques is the study of relationships between seed yield as affected by sulphur supply, and the total sulphur concentration in seed. Although the range of sulphur concentrations found in seeds is often narrower than in leaves, significant correlations were obtained between total sulphur concentrations in seed and yield, and critical values have been derived for upland rice, cowpea, and wheat. Piper-Steenbjerg effects have been noticed in some pot experiments, and it-has been observed that nitrogen deficiency depressed grain sulphur concentrations to values... 

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