Agriculture and nitrogen

It is sobering to realize that less than 0.001% of the global N is cycling 

Nitrogen fixation occurs naturally by chemical and/or biological processes, or by commercially-important chemical syntheses. Estimates place the biological processes as by far the major contributor of some 122 X 10 tonnes per annum globally, while lightning and combustion add a further 30 x 10 tonnes, with industrial fixation realizing some 50 x 

Although the family Leguminoseae includes tropical and temperate plants, most of these can be infected by bacteria of the Rhizobium spp, which colonize the plant roots within nodules. It has been estimated that root nodules may supplement soil N by more than 200 kg ha yr - under favourable 

N-fixers, so effective strains are used for inoculation of the plant seed. 

It has been observed that infection by one strain effectively protects the 

---

Mosier A.R. Syers J.K. and Freney J.R. (eds.) (2004). Agriculture and Nitrogen Cycle Assessing the Impacts of Fertilizer Use on Food Production and the Environment. Island Press, Washington, D.C., 344 pp. 

Biocides should not be present in water used for aquaculture. Sources of herbicides and pesticides are mnoff from agricultural land, contamination of the water table, and spray drift from crop-dusting activity. Excessive levels of phosphoms and nitrogen may occur where mnoff from fertilized land enters an aquaculture faciUty either from surface mnoff or groundwater contamination. Trace metal levels should be low as indicated in Tables 4 and 5. 

How have agriculture and deforestation changed the global rates of nitrogen fixation and denitrification How can increased agricultural productivity be sustained without using industrially produced fertilizers ... 

Many malodorous compoimds are not only nuisance, but also a health threat under prolonged exposure [1]. Ammonia (NH3) is emitted from landfill and sewage treatment plant and associated with many agricultural activities (e.g. poultry and piggery). Ammonia is also a problem in public toilets, hospitals and nursing homes. Selective eatalytie oxidation (SCO) can convert NH3 to N2 at mild temperature (i.e. 473-673 K) as shown in equation 1, however nitrous oxides (N2O) and nitrogen oxides (NOj) are often produced cf. Eqn. 2 3). 

Tab. 6.7 Example of nitrogen concentrations in biological, food, agricultural and related reference materials listed in increasing order of concentration ...

The removal of carbobenzyloxy (Cbz or Z) groups from amines or alcohols is of high interest in the fine chemicals, agricultural and pharmaceutical industry. Palladium on activated carbon is the catalyst of choice for these deprotection reactions. Nitrogen containing modifiers are known to influence the selectivity for certain deprotection reactions. In this paper we show the rate accelerating effect of certain N-containing modifiers on the deprotection of carbobenzyloxy protected amino acids in the presence of palladium on activated carbon catalysts. The experiments show that certain modifiers like pyridine and ethylenediamine increase the reaction rate and therefore shorten the reaction times compared to non-modified palladium catalysts. Triethylamine does not have an influence on the rate of deprotection. 

Waghom GC, Stafford KJ. Gas production and nitrogen digestion by rumen microbes from deer and sheep. New Zealand Journal Agricultural Research. 1993 36 493-497. 

Lundquist EJ, Jackson LE, Scow KM, Hsu C (1999) Changes in microbial biomass and community composition, and soil carbon and nitrogen pools after incorporation of rye into three California agricultural soils. Soil Biol Biochem... 

---