The direct production of copper sulphate from copper ore is an important route to recover copper. The condition, however, is dependant on temperature and sulphatising environment. The oxidation of chalcopyrite in static air bed condition has been studied by TG/DTA and DSC techniques. The addition of catalysts, improved the sulphation by in-situ producing better condítions. The mutual effects of sulphides were further confirmed by studying the oxidation reaction on pure copper-iron sulphides and results so obtained were corroborated with X-ray diffractrograms. With only chalcopyrite a mass gain of 8% (TG) corresponding to copper sulphate formation was observed, in the temperature range 628–738 K. The TG plots showed respective mass gain of 14, 17 and 12% in presence of Fe2O3, Na2SO4 and FeSO4 with chalcopyrite in the wider temperature range 628–923 K. As such the cupric sulphide had a negligible tendency of sulphation, which increased with the addition of ferrous sulphide mixture under the temperature range studied. At higher temperature copper ferrite formation was found.
A field study conducted for three years (1992–93 to 1994–95) at the Indian Agricultural Research Institute on a sandy clay loam shows that for sustained production in a rice-wheat cropping system integrated nutrient management involving both organic manures/residues and chemical fertilizers is a must. In control plots receiving no organic manures/residues but as high as 120 kg N ha –1 only 8 t ha –1 yr –1 grain could be produced. This productivity could be achieved by Sesbania/cowpea green manuring or mungbean residue or farmyard manure without any chemical fertilizer; with 80 kg N ha –1 it could be increased to 9 t ha –1 yr –1 . Since the availability of farmyard manure is decreasing due to increased mechanization, the generation of in situ organic residues, preferably a legume, is a better alternative.
Field experiments were carried out for 3 years to assess the efficacy of organic manures (Sesbania, Leucaena, cowpea, mungbean, wheat straw and FYM) in enhancing the productivity of rice and in supplying Fe. Green manuring with Sesbania gave the highest rice yield, whereas the lowest yield was recorded with wheat straw incorporation. The concentration and uptake of Fe by rice was significantly higher with organic manures. The Fe status of the soil after 3 crops of rice declined from the initial value, but the decline was least with FYM, followed by green manures. The application of organic manures is a good source for a sustained supply of Fe in soil.
Authors:P. Chandrasekhar Reddy, K. Prasad and B. Rangamannar
A rapid and sensitive substoichiometric radiochemical procedure has been developed for the extraction of cobalt with potassium
salts of ethyl, propyl, butyl, pentyl and benzyl xanthates. The relative extractabilities of the cobalt-xanthate complexes
into chloroform and carbon tetrachloride were studied. Substoichiometric quantification methods were developed in each case
and utilised to determine the cobalt content present in standard solutions as well as biological samples.
Authors:B. BashyaL, Ramesh Chand, L. Prasad and A. Joshi
Eighty barley genotypes were evaluated for partial resistance components of spot blotch disease of barley caused by Bipolaris sorokiniana under field conditions. Barley genotypes were inoculated with 29 B isolate of Bipolaris sorokiniana and the Area Under Disease Progress Curve (AUDPC), size of lesion, number of lesions leaf−1 and number of spores lesion−1 were recorded for penultimate leaves. A wide range of variation was observed for the components of partial resistance in barley genotypes. AUDPC and size of lesion identified as first principal components for the resistance. Further cluster analysis clustered genotypes into 10 groups and barley genotypes BCU5592, BCU5613, BCU1452, BCU138 and BCU133 exhibited low AUDPC, smaller lesion size, less number of lesions leaf−1 and less number of spores lesion−1. Selecting these genotypes exhibiting resistant components could be helpful in reducing losses caused by disease and thus contribute to increased yield.
Authors:M. S. R. Swamy, T. P. Prasad and B. R. Sant
The literature on thermal analysis of ferrous sulphate heptahydrate in air is reviewed. The oxidation-decomposition of ferrous sulphate heptahydrate is a complex function of experimental conditions. Some general methods including those developed by the authors for the purpose of analyzing various intermediates encountered during the oxidation-decomposition of the heptahydrate are presented and discussed.
Authors:M. S. R. Swamy, T. P. Prasad and B. R. Sant
The thermal decomposition of ferrous sulphate heptahydrate was carried out in air under dynamic and isothermal conditions. The intermediate phases were identified by chemical analysis and an X-ray technique. Ferrous sulphate heptahydrate is converted to tetrahydrate and monohydrate, but this conversion is accompanied by oxidation. Fe(OH)SO4 and Fe2O(SO4)2 are formed as oxidation products, and the latter decomposes to ferric oxide directly and/or through Fe2(SO4)3.