Fertilizers nutrient requirements

Fertilization of ponds to increase productivity is the next level of intensity with respect to fish culture, followed by provision of supplemental feeds. Supplemental feeds are those that provide some additional nutrition but caimot be depended upon to supply all the required nutrients. Provision of complete feeds, those that do provide all of the nutrients required by the fish, translates to another increase in intensity. Associated with one or more of the stages described might be the appHcation of techniques that lead to the maintenance of good water quaUty. Examples are continuous water exchange, mechanical aeration, and the use of various chemicals used to adjust such factors as pH, alkalinity, and hardness. 

A level of analyte enough above the background level to be of concern and require remediation. In agriculture, it might be a low level of nutrient requiring additional fertilizer. 

In the same regard, PPCP introductions through manure and biosolids that are applied to arable land is enhanced by the typically high application rates of these forms of crop fertilizers rates that are usually higher than the crop needs (Kumar et al., 2005). It is recommended that manure and biosolids application rates be based on the nutrient requirements of the intended crop so as to minimize the unintended introduction of these micropollutants into the food chain at levels that can be avoided. 

Others would extend the fertilizer concept to the simultaneous addition of readily biodegradable substrates along with the fertilizer nutrients to stimulate the growth of contaminant-degrading oiganisms most rapidly, and to aid in the rapid utilization of the fertilizer nutrients before they might be leached from the contaminated area. The specific requirements for the most efficacious substrates is an area of current research. 

If there are significant amounts of both volatile and nonvolatile contaminants, remediation may be achieved by a combination of liquid and vapor extraction of the former, and bioremediation of the latter. This combination has been termed "bioslurping", where the act of pumping out the liquid contaminant phase draws in air at other wells to stimulate aerobic degradation (20). Such bioremediation requires that there be enough nutrients to allow microbial growth, and fertilizer nutrients are frequently added at the air injection wells. Bioslurping has had a number of well-documented successes. 

POME has proven to be a good source of organic fertilizer and is available in large volume (Table 29). Applied at rates corresponding to the nutrient requirement of crops, it will not have detrimental impact on the environment. The beneficial effects of POME apphcation on crop yield and performance have been investigated. Several methods of land application systems are available. 

An estimated 7 million metric tons (6.5 million short tons) of potassium carbonate were produced in the United States in 2005. Of that amount, nearly 90 percent was used for the production of fertilizers. Potash provides plants with the potassium they need to stay healthy and grow. Potassium is one of the three major nutrients required by plants, the other two being nitrogen and phosphorus. The next largest application for potassium carbonate is in the chemical industry, where it is used as a raw material to make other chemical compounds, potassium silicate being the most common. 

Nutrient requirements for reproduction are considered in Chapter 15, which also includes nutritional influences on puberty, fertility and fecundity and the requirements for egg production in poultry and growth of the foetus. 

The N/P ratio was increased from 3.9 in raw manure to 5.2 in the bioreactor effluent and to 9.2 in the supernatant fraction of settled effluent. This separation of nutrients increased the agronomic value of manure as it more closely matched crop nutrient requirements. Another advantage of AD manure as fertilizer is reduction in odor, with a high mineralized N content and N P ratio, increases the window in which it can be applied to land to meet nutrient requirements at various stages of crop growth. 

Phosphorus is an essential plant nutrient required for cellular DNA and other biomolecules. It is utilized by plants as H2PO4 and HPO ions. Phosphate minerals that can be used to manufacture phosphorus-containing fertilizers occur in a number of places throughout the world. In the United States, Florida has especially abundant phosphate resources, largely as fluorapatite, Ca5(P04)3F, as well as hydroxyapatite, Ca5(P04)30H. These phosphate minerals are too insoluble to serve directly as fertilizers and are treated with phosphoric acid and sulfuric acid to make superphosphates that are much more soluble and available to plants ... 

This is a formidable list, although by no means complete. Extra benefits are derived from a combination of the afore-mentioned actions. The prevention of the drying-out of the top soil between irrigations or precipitations, which occurs with bare ground, creates ideal conditions for the root system to develop laterally rather than vertically. Such root development is very desirable as it occurs in the top soil where ideal growing conditions are obtained warmth and the presence of beneficial microorganisms which increase the availability of nutrients to the plants. In turn less fertilization is required which is economically desirable [6]. 

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