Recycling nutrients

When considering the availability of nutrients, it is also necessary to examine the significance of nutrient re-use within the waterbody. These internal sources amount not to an additional load, but a multiplier on the recyclability of the same load. This nutrient recycling and the internal stores from which they are recycled are often misunderstood, but there is a dearth of good published data about how these recycling mechanisms operate. Microbial decomposition in the water column is one of several internal loops recognized in recent years, but these are not closed and the flux of nutrients recycled through them is delayed rather than retained. 

Kadko D (1993) Excess °Po and nutrient recycling within the California coastal transition zone. J Geophys Res 98 857-864... 

Energy production Disturbance regulation Nutrient recycling Material processing ... 

Cover crops Improves fertility Improves water availability Nutrient recycling Reduces costs Soil erosion and runoff control Weed control Kalinova (2009) Malezieux et al. (2009) Pati et al. (2009) Runyon et al. (2009) Stagnari et al. (2009) Wu and Sardo (2009) Zuazo and Pleguezuelo (2009)... 

Phenolic acids can be allelopathic but their presence in soil is ephemeral due to rapid degradation and/or sorption by soil particles (Inderjit 2004). Sorption of benzoic acid onto soil particles increased with concentration and it may explain the reason for the limited allelopathic effect of benzoic acid at concentrations often recorded in natural soil (Inderjit 2004). Microorganisms help to generate allelochemicals, but they may also modify toxic compounds into nontoxic compounds (Khanh et al. 2005). Allelochemicals are changed in composition and quantity during the residue decomposition. Allelopathy plays an important function in nutrient recycling (Rice 1984). 

WASTE NUTRIENT RECYCLING USING HYDROPONIC AND AQUACULTURAL METHODS. (1975) (Sponsor Rockefeller Foundation)... 

Expressed in the simplest terms, the glomeruli are filters and the tubules execute active and passive transport between the tubular fluid (glomerular filtrate) and the blood. The combined and coordinated function of the glomeruli and tubules constitutes the renal waste disposal and nutrient recycling system. 

Most species of insects are beneficial or even essential to agriculture. Honeybees, for example, are responsible for the pollination of 10 billion worth of produce in the United States. Countless other species take part in nutrient recycling and help maintain soil quality. A small minority of insect species, however, has continually threatened our capacity to grow, harvest, and store crops, and it is against these species that insecticides are used. The most widely used insecticides are chlorinated hydrocarbons, organophosphorus compounds, and carbamates. 

Vanni, M., and C. Layne. 1997. Nutrient recycling and herbivory as mechanisms in the top-down effect of fish on algae in lakes. Ecology 78 21-40. 

Billen, G. 1982. Modeling the processes of organic matter degradation and nutrients recycling in sedimentary systems. In Sediment Microbiology (D. B. Nedwell and C. M. Brown, Eds.), pp. 15-52. Academic Press, London. 

Seitzinger, S.P, Gardner, W.S., and Spratt, A.K. (1991) The effect of salinity on ammonium sorption in aquatic sediments implications for benthic nutrient recycling. Estuaries 14, 167-174. 

Organic agriculture in its present form may not render agricultural self-sufficiency in Sub-Saharan Africa possible without further nutrient mining. It does, however, have much to contribute to the sustainability of crop production when implemented judiciously at suitable locations, particularly if techniques to replenish soil P stocks and realise hygienically and environmentally safe nutrient recycling from organic wastes and excreta are adopted. 

The significant investment made in superficial roots by trees of Amazon forests is a clear indication of the importance of nutrient recycling from organic pools at the soil surface. However, research from the central and eastern Amazon has shown that trees in seasonally dry forests also have roots extending to at least 18 m depth (Nepstad et al. 1994). While the main function of these roots appears to be the uptake of deep soil water and groundwater, there is also potential for these roots to access deeper nutrient pools in the soil column. Nepstad et al. (this volume) elaborate on this issue by demonstrating that secondary forests growing in the eastern Amazon have P and K nutrient needs that cannot be satisfied by available stocks in the... 

Nutrient recycling and supply is tightly regulated by largely biotic processes, such as retranslocation or resorption prior to leaf abscission (Medina and Cuevas 1989, Cuevas and Medina 1990). Nutrients are also reutilized from decomposing residues through rapid mineralization and uptake by a dense... 

The impacts of trees on soil fertility depend on nutrient recycling characteristics such as litter chemistry and decomposition rates. Tree litter can be used as mulch with different outcomes a fast mulch decomposition rate may accelerate the growth of associated crops on poor soils, while in other cases a more persistent litter may provide a steady source of nutrients and a better soil cover year round. In the experiments in Costa Rica described in the previous section, high rates of litterfall and slower decomposition resulted in high litter accumulation and high... 

When rain forests are cut down, for example, and converted to fields of rice or corn, the nutrient recycling mechanisms are destroyed, and as a result, the productivity of the field quickly declines. A much better approach would be to devise a production system whereby the nutrient recycling mechanisms are left intact. Extractive reserves for Brazil nuts and rubber are examples of management approaches that are compatible with sustainability of harvest (Brown et al. this volume). The trees are not destroyed when the nuts and the rubber are harvested, and consequently, the nutrient recycling mechanisms of the forest remain intact. A problem with extractive reserves however, is... 

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