Fertilizers mineral nitrogen

Percentage of labelled fertilizer nitrogen left in soil at harvest, and percentage increase in soil mineral nitrogen at harvest caused by fertilizer ... 

Being on-farm emissions (from cultivation and animals breeding) the most important source of GHG in food life cycle, numerous studies have tried to reduce them. Ahlgren [55] has used LCA to evaluate the use of biofuels in tractors and the substitution of mineral nitrogen fertilizers. This implied that 3-6% of a farm s available land was needed to produce the required biomass (to produce biofuels and fertilizer). 

According to modem standards mineral fertilizers are partitioned into two groups standardized and non-standardized. The standardized fertilizers include nitrogen, phosphoms, potassium, complex, and micro-fertilizers that contain the nutrients at the standard basis. The non-standardized fertilizers are municipal wastewater effluents, municipal solid wastes, polluted river waters used for irrigation, etc., which are not characterized by standard content of nutrients. However one should add that in all fertilizers including standardized type there are the admixtures, which pollute the agrolandscape. The known examples are phosphoms fertilizers and any municipal waste and wastewater with a pool of heavy metals and various organic pollutants. 

For abbreviations see Table 14.2. U, unfertilized NPK, mineral nitrogen + phosphate + potassium fertilizer. 

Remark whereas in organic farming mineral nitrogen fertilizers, herbicides or conventional pesticides are forbidden, they are allowed in other so-called environmental friendly system approaches, e.g. sustainable agriculture or conservation agriculture (see Dumanski et al. 2006). 

The consumption of mineral nitrogen-containing fertilizers is given in Tables 2.2-1 to 2.2-3. 

In the year ending June 30, 1991, 77.0 million metric tons of nitrogen fertilizer were used worldwide with 10.1 million metric tons in the United States alone [4], Nitrogen can be added to soil by natural means such as crop rotation, natural organics, mineral nitrogen, or by synthetic nitrogen fertilizers. 

Fertilization of arable lands and grassland soils with mineral nitrogen favors the formation of nitrosamines in soil. Formation of nitro and nitroso and other compounds has been observed, which are precursors of nitrosamines. They are also products of biotransformation of some pesticides and other precursors. Dynamics of the formation and development of nitrosamine precursors in soil depend on many physicochemical factors but soil acidification processes undoubtedly favor it. Once they are formed they remain in soils for between 90 and 128 days and in aquatic environment for 80-110 days. 

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