Phosphorus losses

Heathwaite AL (1997) Sources and pathways of phosphorus loss from agriculture, pp 205-223. 

Increases in phosphorus export from agricultural landscapes have been measured after the application of phosphorus. Phosphorus losses are influenced by the rate, time, and method of phosphorus application, form of fertilizer or manure applied, amount and time of rainfall after application, and land cover. These losses are often small from the standpoint of farmers (generally less than 200 kg P km-2) and represent a minor proportion of fertilizer or manure phosphorus applied (generally less than 5%). Thus, these losses are not of economic importance to farmers in terms of irreplaceable fertility. However, they can contribute to eutrophication of downstream aquatic ecosystems. 

Sims JT, Simard RR, Joern BC (1998) Phosphorus loss in agricultural drainage—historical perspective and current research. J Environ Qual 27 277-293 Spoor M (1998) The Aral Sea Basin crisis Transition and environment in former Soviet Central Asia. Develop Change 29 409-435... 

Sims, J.T., Simard, R.R., Joern, B.C. 1998. Phosphorus loss in agricultural drainage historical... 

In addition to thermal decomposition of the substrate, holding the system at elevated temperatures for long times can result in volatilization of desired constituents. As an example, Figure 5 shows the amount of phosphorus loss from In-P solutions in terms of a decrease in the liquidus temperature as a function of baking time at 670 °C (55). This level of evaporative loss is significant and must be accurately accounted for to control subsequent growth. In addition, the evaporating species can be transported downstream to other bins and alter the composition of these melts. 

There can be increases in calcium and phosphorus loss because of effects on both the kidney and the bowel, with increased excretion and reduced resorption (131). Tetany, which has been seen in patients receiving high-dose longterm intravenous glucocorticoids, has been explained as being due to hypocalcemia, and there are also effects on bone. Tetany has also been reported in a patient with latent hyperparathyroidism after the administration of a glucocorticoid (122). 

Kronvang et al. (2005) summarized the effects of buffer zones on phosphorus losses and some of the other primary mitigation practices implemented to date, and discussed factors that may delay or even counteract these practices when monitored at the catchment scale. 

Kronvang, B., M. Bechmann, H. Lundekvam, H. Behrendt, G.H. Rubaek, O.F. Schoumans, N. Syversen, H.E. Andersen, and C.C. Hoffmann (2005). Phosphorus losses from agricultural areas in river basins Effects and uncertainties of targeted mitigation measures. J. Environ. Qual., 34(6) 2129-2144. 

Lentz R. D., Sojka R. E., and Robins C. W. (1998) Reducing phosphorus losses from surface-irrigated fields emerging polyacrylamide technology. J. Envirort Qual. 27, 305-312. 

There can be increases in calcium and phosphorus loss because of effects on both the kidney and the bowel, with increased excretion and reduced resorption (110). Tetany,... 

In summary, regeneration of VPMeO catalysts, deactivated because of oxidation and/or phosphorus loss, can be successfully conducted using mechanochemical or barothermal treatments. By these methods it is possible to increase the selectivity of the spent catalyst by 9-23% which is a better result than that obtained by treatment with phosphorus-organic compounds. 

G. Morgan, Q. Xie and M. Devins, (2000) Small catchments -NMP Dripsey - water quality aspects. In Tuimey, H. (ed.) Quantification of Phosphorus Loss from Soil to Water, EPA, Wexford, pp. 24-37. 

G. Morgan (2000), Quantification of phosphorus loss from soil to water, EPA, Wexford. 

Catt JA, Howse KR, Faeina R, Beockie D, Todd A, Chambees BJ, Hodgkinson R, Haeeis GL and Quinton JN (1998) Phosphorus losses from arable land in England. Soil Use and Management 14 168-174. 

For example, some plants can increase root volume and surface area to optimize uptake potential. Alternatively, plant roots and/or associated fungi can produce chelating compounds that solubilize ferric iron and calcium-bound phosphorus, enzymes and/or acids that solubilize phosphate in the root vicinity. Plants also minimize phosphorus loss by resorbing much of their phosphorus prior to litterfall, and by efficient recycling from fallen litter. In extremely unfertile soils (e.g., in tropical rain forests) phosphorus recycling is so efficient that topsoil contains virtually no phosphorus it is all tied up in biomass. 

How much does the decrease in organic phosphorus contribute to total phosphorus loss, and can a decrease in organic phosphorus occur even when total phosphorus increases ... 

Are there pathways of phosphorus loss other than export with harvested products ... 

Reference Crops Phosphorus input (kg/ha/year) Years Change in total phosphorus (mg/kg) Phosphorus loss as organic phosphorus (%) Relative change (%) ... 

Phosphorus export data necessary to reveal phosphorus losses other than export in harvested products was reported only by... 

Reddy et al. (1999). In this study, the amount of total phosphorus lost during 4 years was similar to the amount of phosphorus exported with harvest products. Loss of total phosphorus in the Tanzanian trial after 3 years of cultivation translated into an annual loss of 83 kg P/ha, whereas after 15 years an additional phosphorus loss of only 44 kg P/ha was observed (Solomon and Lehmann, 2000). Clearly, other pathways of phosphorus loss, such as erosion of phosphorus-enriched topsoil after woodland clearing, must have been relevant. Likewise, annual phosphorus losses of 17—19 kg P/ha in a study from Ethiopia (Solomon et al., 2002) appear to be at the high end for phosphorus exports from unfertilized maize. In addition, significant reductions in total phosphorus under plantations of tea and Cupressus, despite low mineral fertilizer inputs, suggest that phosphorus loss through erosion and/or leaching occurred. 

Figures 15.4, 15.5 and 15.6 show the simulated changes in the soil-plant system during 4.1-million-year soil development. The model results are compared with observed data from the LSAG sites with a focus on plant production, inorganic phosphorus fractions, soil organic carbon, nitrogen and phosphorus, nutrient mineralization rates, soil respiration, nitrogen and phosphorus losses, and live leaf nutrient ratios. A key assumption in the model run is that climate remained constant during the 4.1-million-year simulation in fact the...

Fig. 15.6. CENTURY model-simulated results for soil phosphorus loss (organic and inorganic phosphorus) total nitrogen loss (nitrate, gaseous nitrogen and dissolved organic nitrogen) and nitrate loss (a) and change in live leaf carbon-to-nitrogen and carbon-to-phosphorus ratios (b) for the Hawaiian 4.1 million year soil chronosequence.

The CENTURY model simulates losses of nitrogen via gas fluxes (N2, N2O and NOJ, dissolved organic loss, and nitrate leaching loss, while phosphorus is lost via dissolved organic and inorganic phosphorus. Model results (Eig. 15.5b) show that total phosphorus loss is quite high during the first... 

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