Fertilisers synthetic

Results after the first and second rotation. The systems varied in fertiliser (synthetic or organic), winter cover crop and irrigation frequency (Cunapala and Scow 1998). 

The physical group undertook mainly analytical work in the field of technically interesting substances, such as catalysts, fertilisers, synthetic polymers, and metals. It set high standards and improved on the analytical methods. In 1941, Brill left LG. Farben and joined the Darmstadt Technische Hochschule as professor of inorganic and physical chemistry. ... 

Uses of ammonia and ammonium compounds. Most of the ammonia produced is used in the manufaeture of nitrogenous fertilisers such as ammonium sulphate. Other uses include nitric acid and synthetic fibre and plastic manufacture. 

Sodium nitrate is used as a fertiliser and in a number of industrial processes. In the period from 1880—1910 it accounted for 60% of the world fertiliser nitrogen production. In the 1990s sodium nitrate accounts for 0.1% of the world fertiliser nitrogen production, and is used for some specific crops and soil conditions. This decline has resulted from an enormous growth in fertiliser manufacture and an increased use of less expensive nitrogen fertilisers (qv) produced from synthetic ammonia (qv), such as urea (qv), ammonium nitrate, ammonium phosphates, ammonium sulfate, and ammonia itself (see Ammonium compounds). The commercial production of synthetic ammonia began in 1921, soon after the end of World War I. The main industrial market for sodium nitrate was at first the manufacture of nitric acid (qv) and explosives (see Explosives and propellants). As of the mid-1990s sodium nitrate was used in the production of some explosives and in a number of industrial areas. 

Nitrogen compounds These also arise from both natural and synthetic sources. Thus ammonia is formed in the atmosphere during electrical storms, but increases in the ammonium ion concentration in rainfall over Europe in recent years are attributed to increased use of artiflcial fertilisers. Ammonium compounds in solution may increase the wettability of a metaland the action of ammonia and its compounds in causing season cracking , a type of stress-corrosion cracking of cold-worked brass, is well documented. 

Similar findings on dairy farms in Canada were reported by Stonehouse, et al. (2001). The superior economic performance on organic dairy farms was attributed to lower costs of production for almost all material inputs, including dairy herd replacements and livestock feeds. The organic dairy farmers used more land for feed crop production for the dairy cows in order to be as self-sufficient as possible. The conventional dairy farmers imported crop seeds, synthetic chemical fertilisers and pesticides, feedstuffs and herd replacements, with more of their land being devoted to cash crops. 

In energy chains related to the provision of CMG, several GHG-emission relevant credits need to be taken into account. Biogas from municipal organic waste is credited for its fertilising effect, accounting for savings of 0.54 g of synthetic nitrogen... 

The exclusion of Chilean nitrate and all synthetic nitrogenous fertilisers,... 

In contrast, conventional farming can cause mortality in fledglings, as reported for starlings, due to the use of pesticides and synthetic fertilisers, which cause unbalanced diets, but also due to the change of the habitat through, for example, the reduction of ditches and pastures (Tiainen et al. 1989). 

Based on a review of published and grey literature on this issue, it can be concluded that the ban of mineral N-fertilisers and synthetic pesticides on the one hand, and the low level of nitrogen cycling within the farm because of low livestock densities on the other, are important contributions which organic farming makes to water protection. 

Conventional arable (synthetic fertiliser), organic arable (green manures) and organic mixed (green manure and manure) over 15 years. 

Available P was adequate but decreased in all except the synthetic fertiliser treatment. The average P budgets (kg P ha y ) were 3.8 for synthetic fertilisers only, -5.0 for synthetic fertilisers and manure, -S.7 for organic and -7.8 for biodynamic (Oehl et al. 2002). 

Yield is not the only indicator of farm productivity. Inputs used to deliver those yields should also be considered, and can be in the form of materials, as discussed below, but they may also be in different forms. For example, one way to manage soil fertility and pest problems on organic farms is to employ a different rotation from that on conventional farms where synthetic fertilisers and pesticides can perform those tasks. Because of the difference in rotation, which may also mean a larger diversity of crops, the whole farm needs to be considered when determining productivity and profitability. 

In order to compare farming systems CO2 emissions need to be differentiated between the emission due to the burning of fuel (direct energy) and the fuel used for the production and transport of fertilisers, machinery and synthetic pesticides (indirect energy). Haas et al. (1995) found that 70% of CO2 in organic farming resulted from fuel consumption and the production of machinery, whereas 75% of the CO2 emissions in conventional systems were due to N fertilisers, feedstuff and fuels. 

Direct on-farm consumption of fossil energy (e.g. for fuel and oil) needs to be distinguished from indirect energy consumption, which results from the production of synthetic fertilisers and pesticides, the transport of imported feedstuffs and from investment goods such as agricultural machinery (Stolze ef al. 2000). 

Nitrogen is added to the soils in organic forms in crop residues and manures and in synthetic forms (ammonium, nitrate and urea) in fertilisers. The organic nitrogen in soil is slowly mineralised by biological processes, the final stages being to ammonium, nitrate and nitrite.43 The conversion of ammonium to nitrite in soils is rapid, while the conversion of nitrite to nitrate is so rapid that nitrite is rarely detectable in soils. 

The demand for hydrogen, driven by classical applications such as fertilisers or oil refining as well as new applications (synthetic fuels, fuel cells,...) is growing significantly. Presently, most of the hydrogen produced in the world uses methane or another /ossil feedstock, which is not a sustainable option, given the limited fossil resources and need to reduce C02 emissions. This stimulates the need to develop alternative processes of production which do not suffer from these drawbacks. 

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