<text><span class="style10">hemicals in Everyday Life (2 of 4)</span><span class="style7"></span><span class="style10">Agrochemicals</span><span class="style7">At the end of the 20th century, the challenge of feeding the world's growing population can only be met with the aid of chemicals produced by the fertilizer industry. In addition to sunlight, oxygen, carbon dioxide and water, plants require </span><span class="style26">macro-nutrients</span><span class="style7"> - as well as trace elements - from the soil. By far the most important of these are nitrogen (N), phosphorus (P) and potassium (K). The fertilizer industry provides compounds in which these macro-nutrients are in a form that can be readily used by plants, principally as water-soluble salts: nitrogen as nitrates (NO3-) of sodium and potassium, and as ammonium sulfate ((NH4)2SO4); phosphorus as phosphates (PO43-) and potassium as potash (K2O). Commercially produced fertilizers are currently responsible for approximately 50% of Europe's agricultural output.Pesticides have been developed in order to protect crops from predators such as insects (insecticides) and from fungi (fungicides), or simply to prevent them from being overrun by weeds (herbicides). Pesticides have two general modes of action by which they achieve these ends: non-systemically active pesticides do not actually penetrate the plant surface - for this reason they are known as contact killers; systemically active pesticides are taken up by the plant's vascular system and inhibit some life-sustaining process. The latter is more desirable, since the chemical is thereby located within the plant itself and is less prone to being washed away into the surrounding water table, but it is a much more difficult goal to achieve. It is only in the last 50 years that effective systemically active pesticides have proved successful. An example is Glyphosate, a widely used herbicide that kills weeds by inhibiting the biological synthesis of a family of vital amino acids:</span></text>
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<text>ΓÇó WHAT IS CHEMISTRY?ΓÇó NATURAL COMPOUNDSΓÇó MAN-MADE PRODUCTSΓÇó MEDICAL TECHNOLOGYΓÇó THREATS TO THE ENVIRONMENTΓÇó OIL AND GASΓÇó RUBBER AND PLASTICSΓÇó CHEMICALS AND BIO TECHNOLOGY</text>
