K in the literature

Mineralogical budgeting of potassium in soil: A basis for understanding standard measures of reserve potassium. Andrist- Rangel, Y.; Simonsson, M.; Andersson, S.; Öborn, I. and S. Hillier. J. Plant Nutr. Soil Sci. 169:5, pp 605-616 (2006). (http://www3.interscience.wiley.com/cgibin/jhome/10008342)

Abstract: The study was conducted to investigate the relationship between some standard measures of soil reserve potassium (K) and soil mineralogy. Eight different agricultural soils from the N temperate and S boreal regions were studied and analyzed both by standard methods (exchangeable K, 2 M HCl and aqua regia-extractable K) and by quantitative mineralogical methods based on X-ray powder diffraction analysis of spray dried bulk soils. Linear regression and multivariate methods were used to assess the relationships between standard measures of soil reserve K and a number of soil chemical, physical, and mineralogical properties. A mineralogical budgeting approach, to estimate total K and its speciation between different mineral phases, is shown to be accurate after validation against total K analyzed geochemically. This approach enabled us to determine that both HCl and aqua regiaextractable K were highly correlated with K in dioctahedral phyllosilicates and extracted 1%-17% and 5%-45% of total K, respectively. Neither extraction showed any obvious relationship to K in feldspar, which is frequently a larger reservoir of K in the soils examined.

Effect of Long-term Integrated Nutrient Supply on Soil Chemical Properties, Nutrient Uptake and Yield of Rice. Reddy, M.D., Rama Lakshmi, CH.S., Rao, C.N., Rao, K.V., Sitaramayya, M., Padmaja, P and T. Raja Lakshmi. Indian J. of Fertilizers Vol. 2(2), May 2006, pp. 25-28.

Abstract: An experiment on long-term integrated nutrient supply in rice-rice cropping system was conducted for 31 seasons during Kharif and Rabi from 1988 to 2003-04 under irrigated conditions. After 31 seasons of rice cropping, there was an increase in organic carbon from 0.54 to 0.63% and available P from 15 to 20 kg/ha in treatments that received organic and chemical nutrition and 18 kg/ha with continuous application of recommended dose of fertiliser over initial available P status (24.4 kg/ha). There was an increase of 25 kg/ha (RD) of K with 100% RD NPK fertiliser and 17 to 27 kg/ha of K with application of 50 to 75% of RD along with 25 to 50% of RD N through organic source. On the other hand, there was a decrease of 55 kg/ha K without application of any nutrients and 4-14 kg of K decrease with 50-75% of RD NPK fertiliser over the initial value. From the beginning of experiment (1988-89), combination of NPK with organic manures recorded higher grain yield in a year (8.83 to 11.95 t/ha). Highest sustainable yield index (54.85% in Kharif and 47.38% in Rabi) was observed with 100% RD of NPK alone. The highest N, P and K uptake was recorded with application of 50% RD NPK+ 50% N through glyricidia.

Magnesium (Mg) is known as one of the essential nutrients for higher plants. The work of Ding et al., (Annals of Applied Biology, 2006, 149, 111-126) shows that Mg deficiency in rice, resulted in significant reduction in shoot biomass, decrease in total chlorophyll concentration and net photosynthetic rate and reduction in activities of both nitrate reductase and glutamine synthetase. The authors show that there were great antagonistic and moderately synergistic effects between K and Mg, but the effects of K on soluble sugars uptake and translocation, as well as nitrate reductase activity and net photosynthetic rate in the leaves were much more significant than those of Mg.

Effect of potassium nutrition on growth, yield and quality of papaya (Carica papaya L.) Kumar, N.; Meenakshi, N., Suresh, J. and V. Nosov. Indian J. of Fertilizers 2(4): 43-47 (2006).

Abstract: An experiment was conducted in Tamil Nadu at four locations in farmers' fields to study the effect of K nutrition on growth, yield and quality of fruits and latex during 2004-05 in randomised block design with three replications and four treatment combinations (300:300:0; 300:300:150; 300:300:300 and 300:300:450g N:P₂O₅:K₂O/plant/year). The study showed that growth characters like leaf number were significantly influenced by K nutrition at two locations and leaf area at one location. The yield and yield attributing characters showed under the treatment K300 were significantly higher as compared to other treatments. The quality characters viz., TSS, pulp thickness and cavity index increased with increase in K levels except for acidity. With respect to yield of latex no definite trend could be observed with K nutrition but the quality of latex was influenced with K nutrition. The leaf nutrient content was also increased significantly with increase in K nutrition levels.

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