Fertilizers global application

First, the application of fertilizers to the land surface has led to increased runoff of N and P from the land surface. Discharge of human wastes has augmented this flux. It appears that the total global nutrient flux today is about 2.5 times greater than the long-term geologic flux, and results in excess accumulation of organic carbon in the ocean (Meybeck, 1982 Wollast, 1983). Furthermore, because of land use activities, the flux of POC, DOC (Likens et al., 1981), and DIC (Meybeck, 1982) from land via rivers to the ocean has been enhanced. 

Syngas manufactured from various feedstocks is processed into ammonia (for fertilizer production) and methanol. In both cases, gasification-based applications amount to about 10% of global production. Other ehemi-cal applieations inelude the produetion of pure hydrogen or carbon monoxide, for example, acetie acid manufacture... 

Kj0lholt 1997). Is was estimated, however, that at the global scale the input of most metals is higher from industrial sources than from the application of fertilizers and biosolids in farming (Kabata-Pendias and Pendias 2001). Calculated budgets for Cd, Pb and Zn in soils in Poland clearly indicate that typical input of these metals (mainly from biosolids and atmospheric deposition) leads to their accumulation in arable soils (Kabata-Pendias et al. 1989). 

The increased use of fertilizers makes a large contribution to the penetration of elements into the nutritional chain. The fertilizers can contain, depending on their production and origin, high amounts of particular elements, including toxic ones. By the application of such fertilizers, the content of these elements in the soil is increased and they enter plants via their root system. Certain types of fertilizers, particularly natural superphosphates, contain more than 30 mg kg of cadmium and lead. Depending on the soil pH, absorption of these metals and their accumulation in particular parts of plants is encountered. The increased global use of fertilizers fortified by certain microelements has considerably increased their contents in the soil and foodstuffs. 

Figure 1 Major perturbations on the Earth system over the past 300 years and projections for the future (a) emissions of CO2 and (b) gaseous N and S from fossil-fuel burning and land-use activities (c) application of inorganic N and P in chemical fertilizers to cultivated land (d) loading of highly reactive C, N, and P into rivers and the coastal ocean from municipal sewage and wastewater disposal and (e) rise in mean global temperature of the lower atmosphere relative to 1700. Revised after Ver LM, Mackenzie FT, and Lerman A (1999) Biogeochemical responses of the carbon cycle to natural and human perturbations Past, present, and future. American Journal of Science 299 762-801.

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