Organic matter and humus characteristics of some volcanic ash soils of South western Tanzania

Enhancing Dissemination of Soil and Water Research Outputs of SADC UniversitiesThis study was done on soils developed from volcanic parent materials including pumice and ashes originating from various volcanoes in and around the Rift Valley of South Western Tanzania. The soil moisture and temperature regimes in the area are udic and isothermic respectively. One pedon close to Lake Nyasa (Mwaya) had aquic SMR and isohyperthermic STR. Soil OC content varied widely among and within pedons, with surface horizons generally having higher values (high to very high). N levels also varied similarly and correlated very well with OC. C:N ratios were very variable and increased with increasing OC. Based on the distribution of OC, N, C:N ratios and the relationship among these parameters, the Tanzanian volcanic ash soils compare quite well with known Japanese volcanic ash soils, although the absolute values of OC were much higher for Japanese than for Tanzanian soils. Results on humic acid studies indicate that the soils predominantly contain A type humic acids particularly in the surface A horizon, buried A, AB and BA horizons. These horizons are characteristically humusrich with intense dark colors. UV-VIS absorption spectra revealed in some soils the presence of Pg fraction with absorption bands around (280), 450, 570 and 615 nm, which are normally associated with the presence of dihydroxyperylenequinone (DHPQ) nuclei responsible for the absorption bands at those wavelengths. On the basis of ∆log K, RF, HE, PQ values and the UVVIS absorption spectra, the characteristics of HAs of the Tanzanian volcanic ash soils compare very well with Japanese volcanic soil

Structure and predissociation of the 3p sigma D-u (3)Sigma(+)(u) Rydberg state of N2: First extreme-ultraviolet and new near-infrared observations, with coupled-channels analysis

The 3p

The analysis of the content of biologically active phenolic compounds, flavonoids, and glycoalkaloids in harvested red, yellow, and green tomatoes, tomato leaves, and tomato stems

The content of two biologically active phenolic compounds (caffeic and chlorogenic acids), two flavonoids (quercetin glucoside and quercetin rutinoside), and two glycoalkaloids (dehydrotomatine and α-tomatine) in green, red, and yellow tomato peels, tomato leaves, and tomato stems harvested from a growing tomato plant was determined by validated high performance liquid chromatography (HPLC) methods. Validation included determining chromatographic properties of commercial standards, hydrolysis of the two glycosides to quercetin, and isolation of the pure glycoalkaloids from a commercial tomatine mixture by preparative chromatography. Analyses of test samples were carried out using fine powders. These were prepared by hand peeling the tomatoes with a knife followed by freeze-drying of the wet peels and then grinding with coffee grinder. The leaves and stems were also freeze-dried and ground to powders. We found extensive variability in the levels of the evaluated compounds. The green tomatoes contained the highest amount of chlorogenic acid, the tomato leaves had the highest amount of quercetin rutinoside (rutin), and the tomato leaves had the highest amount of individual and total glycoalkaloids. The α-tomatine/dehydrotomatine ratio ranged from 1.45 (tomato leaves), to 1.73 (tomato stems), and 4.57 (green tomato peel). The red and yellow tomato peels did not contain measurable amounts of the two glycoalkaloids. The described methods could be used to determine the compositions of the three classes of bioactive compounds in other tomato varieties, the levels of which might be affected by soil and environmental factors and post-harvest storage conditions. Such studies might facilitate further investigations into the relationship between the compositions to the multiple health benefits of the compounds leading to the possible use of tomato powders with the highest content of bioactive compounds as functional food additives