Potassium soil fertilization

Some compounds of the s-block elements are important industrial chemicals, too. For example, more than 1.4 billion kilograms of K2 CO3 (potassium carbonate, whose common name is potash), is produced in the United States each year. This compound, which is obtained from mineral deposits, is the most common source of potassium for fertilizers. Fertilization with potassium is necessary because this element is essential for healthy plant growth. Moreover, potassium salts are highly soluble in water, so potassium quickly becomes depleted from the soil. Consequently, agricultural land requires frequent addition of potassium fertilizers. 

Occasionally, especially In alkaline soil, trace elements, although present, may not be soluble due to the high pH, and are therefore unavailable to the plant. On these occasions, additional supplies might be needed (see pp.54-55). Mineral deficiencies can also be caused by too much of another element overdo potassium-rich fertilizers, for example, and you may "lock up" magnesium so that plants develop symptoms of magnesium deficiency. 

Gosling, P. and Shepherd, M. 2005. Long-term changes in soil fertility in organic arable farming systems in England, with particular reference to phosphorus and potassium. Agriculture, Ecosystem and Environment 105 425-432. 

Although superphosphate fertilizer provides available phosphorus, it is advantageous to provide other needed elements such as nitrogen and potassium at the same time. Thus, diammonium hydrogen phosphate [(NH4)2HP04] provides both nitrogen and phosphorus, while potassium ammonium phosphate [K(NH4)HP04] makes available the three elements most needed in the maintenance of soil fertility. 

The foundation of modern fertilizer technology was laid by Justus von Liebig in 1840. He postulated that the mineral elements nitrogen, phosphorus, and potassium (N, P, and K) in the soil are responsible for plant nutrition and stressed the necessity of replacing those elements to maintain soil fertility. 

Methods of Mo application include soil application of Mo fertilizer alone or with phosphorus (P) or nitrogen-phosphorus-potassium (NPK) fertilizers (molybdenized fertilizers), foliar sprays, dusts, and seed treatment. 

Plants, like humans and animals, need adequate water, protection from disease, and certain chemical compounds to grow. Soil fertility where no agriculture occurs is maintained at an even level when the waste products derived from plants are returned to the soil. Human agriculture prevents this from occurring. Fertilizers are materials given to plants to promote growth. Nitrogen, phosphorus, and potassium are the most important elements in fertilizers. 

Animals maintain soil fertility. Animals provide manure for the fields, a fact which was often forgotten during the era when chemical fertilizers were relatively abundant and cheap. One ton (907 kg) of average manure contains 18 lb (8.2 kg) of nitrogen, 9 lb (4.1 kg) of phosphorus, and 13 lb (5.9 kg) of potassium. 

Of the various elements that are ktiown to be essential for the proper growth and reproduction of plants, Nitrogen, Phosphorus and Potassium are required in relatively large amounts and so are known as major elements or macro-nutrients. A deficiency of one or more of these elements in soil may limit the growth of a particular plant or crop and may thus decrease soil fertility. 

Brouder SM, Thom M, Adamchuk VI et al (2003) Potential uses of ion-selective potassium electrodes in soil fertility management. Commun Soil Sci Plant Anal 34 2699-2726... 

The greatest demand for potash has been in its use for fertilizers. Potassium is an essential constituent for plant growth and is found in most soils. 

Potassium nitrate is being used increasingly on intensive crops such as tomatoes, potatoes, tobacco, leafy vegetables, citms, and peaches. The properties that make it particularly desirable for these crops are low salt index, nitrate nitrogen, favorable N K20 ratio, negligible CU content, and alkaline residual reaction in the soil. The low hygroscopicity of KNO (Table 9) leads to its use in direct appHcation and in mixtures. It is an excellent fertilizer but the high cost of production limits its use to specialty fertilizers. 

However, the fertilizing effect of nitrates (and sulfates) may be counterbalanced by the leaching of potassium, magnesium, calcium, and other nutrients from forest soils. There is little evidence that agricultural crops are being injured by exposures to nitrates in precipitation. The amount of nitrates in rainwater is almost always... 

McCracken et al. 164) compared atomic absorption with the tetraphenyl-boron method for determining potassium in 1190 fertilizers, and very close agreement was found between the two methods. Hoover and Reagor 16S) also found good agreement between the two methods, and atomic absorption was far more rapid. They reported that the 7665 A potassium line was more subject to interference than the less sensitive 4044 A line. Temperli and Misteli 166> reported far better results for low concentrations of potassium in soil extracts by atomic absorption spectroscopy than by flame emission spectroscopy. 

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