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[en] The requirements for nitrogen and phosphorous fertilizers for growing cotton (Gossypium hirsutum L.) in Kenya are 26-kg N ha-1 and 27 kg P ha-1, respectively. Calcium ammonium nitrate (CAN) was recommended at the rate of 100 kg ha-1 for black cotton soils while double superphosphate (DSP) was recommended at the rate of 150 kg ha-1 on reddish brown clays. However, experiments conducted on a major soil types on which cotton is grown in Kenya showed that, soil colour is not the best indicator of nutrients supply power of the soil. It was found that Verto-eutric planosols of National Fibre Research Centres-Kibos requires application of 13-kg ha-1 as CAN for optimal yields. Ferralo-eurtric Acrisols of Alupe Agricultural Research Sub-Centre, Busia needed 26-kg N ha-1 and 9 kg P ha-1 to give high yields. At Siaya FTC 9 kg P ha-1 was adequate in providing the highest yields without nitrogen. Strict observation of recommended agronomic practices for growing cotton and good soil management practices for growing cotton and good soil management practices were observed a prerequisite for high response and efficient utilisation of fertilizers
[en] A mixture with different compositions of HA and TCP were synthesized in this work by precipitation method using Ca(NO3)2 4H2 and (NH4)2HPO4 as the starting materials. A mixture with HA and TCP phases in different ratios were produced. The powders were sintered from 1000 degree C to 1250 degree C. The phase compositions of the mixtures were then studied via XRD. This work shows that the pH value determines the different phase compositions of the HA-TCP mixture. Chemical analyses were carried out by FTIR. The microstructure was observed under SEM. (Author)
[en] Distribution behavior of Ce(III), Am(III), and Cm(III) between tri-n-butyl phosphate solution and molten calcium nitrate hydrate Ca(NO3)2 · RH2O or molten calcium chloride hydrate CaCl2 · RH2O was studied radiochemically. In Ca(NO3)2 · RH2O systems, maximum separation factors of Ce and Cm to Am were observed to be 12 (Ce/Am) and 1.7 (Cm/Am). The distribution ratios of these elements increased with the decrease of water activity in the hydrates, and the extractabilities at the water deficient region was less sensitive compared to those at the water abundant region. This trend was similar to the coordination circumstance change observed in electronic absorption spectra of Nd(III) in the hydrates. (author)
[en] The electroreduction of uranyl ions in buffered and unbuffered 0.5 M calcium nitrate has been studied using polarography, cyclic voltammetry, chronopotentiometry, and chronoamperometry. The results are compared with those in molten calcium nitrate tetrahydrate. (author)
[en] The ion exchange process of alloy of alkaline metals salts with divalent cations on alkali aluminosilicate and alkali aluminosilicate germanate glasses was studied. The data on the change of glass composition in diffusion layer was obtained by means of study the dependences of refractive index as well as the weight change before the ion exchange and after.
[en] Specimens of different types of soil, namely chernozem, brown soil and illimerized soil were taken in the environs of the nuclear power plant construction site. 0.0285 MBq of 85Sr in chloride form was added. Solutions of NaNO3, KNO3 and Ca(NO3)2 of different concentrations and their mixtures were used in studying the effect of salts on strontium sorption. The sorption was studied under steady-state conditions. The eluate samples were measured with an NZQ 201 spectrometer. The 85Sr sorption by soils in the presence of the individual salts and their mixtures was found to depend on the type of soil. The highest 85Sr sorption value was found for chernozem while a low radiostrontium sorption was observed for brown soil. The reducing effect was confirmed of elevated salt content in the soil on 85Sr sorption. The results obtained are discussed in detail. (E.S.) 1 tab., 2 figs., 6 refs
[en] Few studies have quantified the accuracy of soil metal bioavailability assays using large datasets. A meta-analysis from experiments spanning 6 months to 13 years on 12 soil types, compared bioavailability estimate efficiencies for wheat and ryegrass. Treatments included biosolids ± metals, comparing total metal, Ca(NO3)2, EDTA, soil solution, DGT and free ion activity. The best correlations between soil metal bioavailability and shoot concentrations were for Ni using Ca(NO3)2 (r2 = 0.72) which also provided the best estimate of Zn bioavailability (r2 = 0.64). DGT provided the best estimate of Cd bioavailability, accounting for 49% of shoot Cd concentrations. There was no reliable descriptor of Cu bioavailability, with less than 35% of shoot Cu concentrations defined. Thus interpretation of data obtained from many soil metal bioavailability assays is unreliable and probably flawed, and there is little justification to look beyond Ca(NO3)2 for Ni and Zn, and DGT for Cd. - Highlights: → A meta-analysis evaluated the efficacy of soil metal bioavailability assays. → DGT could explain 49% of shoot Cd concentration. → There is little justification to look beyond Ca(NO3)2 for Ni and Zn. - A meta-analysis of soil metal bioavailability estimates for 12 soil types concluded that there is little justification to look beyond Ca(NO3)2 for Ni and Zn, and DGT for Cd.
[en] The single use of CaO has been regarded as relatively unsuccessful in fly ash activation when no other additives are used together, as it produces a considerably lower strength compared to other types of activators (e.g., alkaline activators). This study investigated two potential additives of nitrate compounds (i.e., Ca(NO3)2 and NaNO3) to improve the strength of a CaO-activated fly ash system. The results showed that the use of Ca(NO3)2 was greatly beneficial in the strength improvement of the binder system primarily due to the significant increase in (1) the dissolution degree of fly ash, (2) C–S–H formation, and (3) pore size refinement from early days; however, NaNO3 was much less advantageous in strength improvement, although it also aided in dissolving fly ash.