Tillage force prediction from terrain characterization with the bevameter

The relationship between the soil parameters measured during soil testing using the bevameter system and horizontal forces acting on a simple tillage tool were investigated. Field experiments were conducted on untilled, compacted and recently tilled soil. On both soils, five sites were randomly chosen where bevameter and draft measurements were performed. The parameters measured were modulus of soil deformation, wet and dry bulk density, soil moisture content, tool operating depth, tool operating speed and horizontal draft.

A statistical analysis of data indicated that a mathematical model for predicting draft should include operating depth, dry bulk density and modulus of deformation.     

Die horizontale Verteilung von Radiocäsium im Waldboden unter Fichte und Buche

Horizontal distribution of radiocesium in forest soils under spruce (Picea abies (L.) Karst.) and beech (Fagus sylvatica L.) The horizontal distribution of radiocesium in the soil under the canopy of several beeches and spruces was examined. At the base of spruces mean ¹³⁷Cs activities are about twice, and under beeches 5 to 15 times as high as under more distant parts of the canopy. Between 80 and 95% of the ¹³⁷Cs activity can be attributed to the Chernobyl fallout, the rest to the global fallout from weapons testing in the 1950s and 1960s. While the ¹³⁷Cs accumulation at the base of spruces can be explained by litter fall and remains of bark, the up to 30 times increased values at the base of beeches are explained by stemflow. Mean activity of radiocesium in the bark of spruce (0,62 Bq/g dry weight) is about twice as high as in the bark of a beech. This can be explained by considering that in contrast to beeches the ¹³⁷Cs activity in the soil under spruces is corresponding to some extend with the main rooting zone. Thus, we expect an increased uptake by the roots of this species and a subsequent transfer to the bark.     

Effect of low pO2 on colonization of maize roots by a genetically altered Pseudomonas putida [PH6(L1019)]

Among the factors which may affect colonization of roots by soil bacteria is that of rhizosphere oxygen partial pressure (pO₂). The oxygen concentration in the root zone influences both microbes and roots. Roots exposed to low pO₂, as might occur during flooding and waterlogging of the soil, become more leaky and loss of soluble carbon increases. To determine whether periods of low pO₂ increased root colonization by a genetically altered pseudomonad we inoculated 3- to 4-week-old maize plants, grown in soil and transferred to a hydroponic system or grown in fritted clay, with Pseudomonas putida PH6(L1019)(lacZY+) following exposure of the roots to air or cylinder N₂. Numbers of heterotrophs and the marked pseudomonad were determined by dilution plating. Low pO₂ generally increased the numbers of bacteria associated with roots exposed to the treatments in solution or in undisturbed fritted clay rooting medium. Under low pO₂ in a hydroponic system, roots of intact maize plants tended also to have higher soluble organic C and hexose (anthrone-detectable sugars) than roots exposed to air. The effect of low pO₂ was most pronounced in the fritted clay where low pO₂ favored colonization by the marked strain; numbers were 3- to 96-fold greater than those on roots flushed with air but accounted for only 0.06–0.61% of the total population. Roots exposed to low pO₂ tended to accumulate more C. Results suggest that in the fritted clay, the pseudomonad was able to exploit the increased C supply and to achieve greater numbers on roots exposed to low pO₂, whereas the dilution of carbon released from roots in the hydroponic apparatus did not allow for the same magnitude of increase on roots. Received: 2 December 1996     

Antioxidative activity in the pericarp and seed of Japanese pepper (Xanthoxylum piperitum DC)

The antioxidative activity of the dried pericarp and seed of Japanese pepper was studied. The ethyl acetate extract from the pericarp and the methanol extract from the seed showed strong antioxidative activity against linoleic acid by the ferric thiocyanate and thiobarbituric acid (TBA) methods. Japanese pepper contained 3.9 and 2.9 mg/100 g of dry weight (dw) of tocopherols in the pericarp and seed, respectively, alpha-Toc in the former constituting 82% of total tocopherol and gamma-Toc in the latter constituting 96%. Arbutin and magnoflorine were isolated as antioxidants and their chemical structures determined by instrumental analyses. The contents of arbutin evaluated as the trifluoroacetate derivative by GC-MS were 35 and 3.0 mg/100 g of dw in the pericarp and seed, respectively. Magnoflorine was present only in the seed, and not in the pericarp. Both arbutin and magnoflorine exhibited antioxidative activity against linoleic acid and radical-scavenging activity against the DPPH radical.     

Differential inhibition of human platelet aggregation by selected Allium thiosulfinates

Thiosulfinates (TSs) have been implicated as a principle source of the antiplatelet property of raw onion and garlic juice. The in vitro responses of human platelets to dosages of four TSs were measured using whole blood aggregometry and compared by regression analysis. Of the compounds evaluated, methyl methane-TS (MMTS), propyl propane-TS (PPTS), and 2-propenyl 2-propene-TS (allicin) are present in freshly cut Allium vegetables, whereas ethyl ethane-TS (EETS) has not been detected. All TSs were synthesized using a model reaction system. PPTS and allicin had the strongest antiplatelet activity at 0.4 mM, inhibiting aggregation by 90 and 89%, respectively. At the same concentration, EETS and MMTS were significantly weaker, inhibiting 74 and 26%, respectively. Combinations of TSs were not additive in their inhibition of aggregation, indicating that the antiplatelet potential of Allium extracts cannot be easily predicted by quantifying organosulfur components. EETS, PPTS, and allicin were significantly more potent platelet inhibitors than aspirin at nearly equivalent concentrations.     

Direct spectrophotometric determination of ferbam (Iron(III) dimethyldithiocarbamate) in commercial sample and wheat grains using 4,7-diphenyl-1,10-phenanthroline

A procedure has been developed for the determination of iron(III) dimethyldithiocarbamate by converting it into the iron(II)-bathophenanthroline complex, which is then dissolved in acetone-water (1:1), and the absorbance is measured at 534 nm against a reagent blank. Beer's law is obeyed over the concentration range 0.5-20 microg x mL(-1) in the final solution. The method is sensitive and highly selective and is used for the direct determination of ferbam in a commercial sample and in mixtures with various dithiocarbamates (ziram, zineb, maneb, etc.) and from wheat grains.     

Esterified phenolics of the cell walls of chufa (Cyperus esculentusL. ) tubers and their role in texture

Chufas (Cyperus esculentus) are edible tubers that, like Chinese waterchestnut (CWC), are very crisp when raw and do not soften when cooked. The present study compares the mechanical properties of chufas with those of potato and CWC in relation to the carbohydrate and phenolic compositions of the cell walls. The cutting toughness of raw chufa was higher than that of raw CWC and potato; its value decreased on boiling, as also observed with CWC, but remained over twice that of raw potato. Chufa cell walls were rich in xylose, arabinose, glucose, uronic acid, and galactose, with minor quantities of mannose. The cell walls of the parenchyma exhibited a uniform pH-dependent autofluorescence indicating the presence of cinnamic acid derivatives. Analysis of these revealed that peeled tuber cell walls are rich in ferulic acid, whereas p-coumaric acid dominates the monomeric phenol fraction of the skin. Cell wall material from both skin and peeled tubers contains a significant amount of different diferulic acids ( approximately 20% of the wall ferulic acid), consisting mainly of the 8-O-4'-, 8-5'-, and 5-5'-dimers. These are potentially available to form thermally stable cross-links between polysaccharides within the wall and between cells. This may confer thermal stability of texture.     

Novel trisaccharide fatty acid ester identified from the fruits of Morinda citrifolia (Noni)

Two known glycosides and a novel trisaccharide fatty acid ester were isolated from the n-butanol-soluble fraction of the fruits of Morinda citrifolia (noni). Structure determination was carried out by spectral techniques such as MS, IR, NMR, and 2D-NMR. The novel trisaccharide fatty acid ester was elucidated as 2, 6-di-O-(beta-D-glucopyranosyl)-1-O-octanoyl-beta-D-glucopyranose. The known compounds were identified as rutin and asperulosidic acid.     

Nitrogen fertilizer influence on aflatoxin contamination of corn in Louisiana

Studies were conducted in 1997 and 1998 on a Gigger silt loam at the Macon Ridge Research Station at Winnsboro, LA, to determine the influence of nitrogen (N) rate, timing, and starter nitrogen fertilizer on aflatoxin contamination in corn. Fertilizer N (0, 50, 100, 150, 200, and 250 lb of N/acre), two timings (at planting and six-leaf stage), and starter N fertilizer (a control and 10 lb of N/acre applied in furrow) were evaluated. Application of starter, N rates, and the interaction of starter with N timing and N rates significantly affected aflatoxin levels. Rates of 50-250 lb of N/acre were 34-43% lower in aflatoxin contamination than plots receiving no N. The application of 10 lb of N/acre starter reduced the aflatoxin levels by 20% compared to the no-starter control.     

CROSS POLARISATION 13C-N.M.R. SPECTROSCOPY OF SOME GENETICALLY RELATED NEW ZEALAND SOILS

Cross polarisation ¹³C-n.m.r. spectra of seven New Zealand soils have been determined. Some of the soils are genetically related. The results show that the aromaticity of a soil may vary widely from soil to soil even when the parent material and vegetation are similar. The youngest of the soils examined (Hokitika, 300 years), was highly aromatic, and the oldest soil (Okarito, 22,000 years) was more aliphatic.