The depiction of soil profiles since the late 1700s

Artists have depicted soils in paintings since medieval times, and most landscape and soil paintings were made in the eighteenth century. The systematic study of soils started later and soil science was dominated by agricultural chemistry for most of the nineteenth century. Since the late 1800s soil profile drawings, paintings and photographs have been depicted in hundreds of textbooks. This paper traces the depiction of soil profiles in the scientific literature from the late 1700. The first soil profile depictions were simple diagrams illustrating different layers and soil processes. Photographs started to appear in textbooks at the end of the nineteenth century. In the 1950s, several books contained water paintings and from the 1970s onwards textbooks had colour photographs. Soil profile depictions were merely used to illustrate different orders in a classification system. Since the 1990s, efforts have been made to depict the soil profile in 3D. The overall trends and pattern found in this analysis not only reflect the technical ability to depict soils (e.g. camera, printing techniques) but also reflect the state of knowledge on the key properties and processes that have formed a soil.     

Heterosis and combining ability for yield and resistance to grain mold in tannin-free photoperiod-insensitive sorghum [Sorghum bicolor (L) Moench] in Senegal

Journal of Crop Science and Biotechnology - Increasing sorghum production per unit area in the farmer’s field by developing high yielding tannin-free and grain mold tolerant varieties in...     

Penetration of hardwoods by liquids

Summary Oven dry highly evacuated sticks of the sapwood of various hardwoods, 40 cm long by 1.0 to 1.2 cm in the radial and tangential directions, took up water to the extent of 44 to 82% of saturation by capillary flow in one minute. Heartwood sticks took up 15 to 38% of saturation in one minute. The initial rapid penetration was followed by a penetration in which the take up increase directly with the square root of elapsed time. In this range, the slope of toluene take up plots was about twice that of the water take up. This is close to the theoratical value on the basis of viscous flow control. The linear portion of the plots is followed by a curvilinear decrease in rate of take up to a final equilibrium value. Water take ups approached 100% of the theoretical values.Times to 0.99 of theoretical filling with water varied from 9 minutes for tupelo gum sapwood to 14.6 to 17.3 days for white oak heartwood. Complete filling with toluene was never attained. Diffuse porous hardwoods filled to the extent of 93.5 to 96.5% of saturation. Ring porous oaks filled to the extent of 88 to 92%, the lower values being for heartwood. Edge coating of the sapwood of yellow poplar and yellow birch with epoxy glue reduced the rate of penetration only slightly. End coating reduced the rate to a higher degree. Moisture gradients in the fiber direction for tyloses-free hardwoods were negligible at various stages of penetration, indicating that filling of the vessels was practically instantaneous. White oak heartwood gave an initial longitudinal gradient followed by a negligible gradient, indicating that longitudinal penetration is primarily through the lumen of the fibers rather than continously through the vessels. Longitudinal penetration was calculated to be 31.5 times as deep as transverse penetration in 100 minutes and 33.3 times as deep in 25 minutes for white oak heartwood. The ratios are of the same order of magnitude as for Loblolly pine. In both cases the ratios are smaller than values calculated from the fiber dimensions alone as ray cell penetration and cross grain effects tend to lower the ratios.Paper No. 3947 of the Journal Series of North Carolina State University Agricultural Experiment Station, Raleigh, N. C.     

Deriving river networks and catchments at the European scale from medium resolution digital elevation data

The extraction of drainage networks and catchment boundaries from digital elevation models (DEMs) has received considerable attention in recent years and is recognized as a viable alternative to traditional surveys and the manual evaluation of topographic maps. However, most studies have covered limited areas due to the lack of detailed information and/or the lack of highly efficient algorithms. In this paper we present an application that delineates river networks and catchment boundaries across the European continent from a medium resolution (250 m) DEM. We exploit novel algorithms based on the concepts of mathematical morphology and implement a landscape stratification for drainage density.A flow direction grid is computed using an efficient algorithm for the removal of spurious pits. River networks are then derived by imposing a variable threshold for the minimum contributing area needed to form and maintain a channel. This is achieved through a landscape stratification that reflects the ability of the terrain to develop different drainage densities. It is shown that the analysis of environmental characteristics coupled with the analysis of local slope versus contributing area enables river network mapping with a spatially varying drainage density. The result has been validated by comparing the derived data to digital river and catchment data from other sources and with varying scales of observation.     

Evaluation of the effect of germination on phenolic compounds and antioxidant activities in sorghum varieties

The screening of 50 sorghum varieties showed that, on average, germination did not affect the content in total phenolic compounds but decreased the content of proanthocyanidins, 3-deoxyanthocyanidins, and flavan-4-ols. Independent of germination, there are intervarietal differences in antioxidant activities among sorghum varieties. Phenolic compounds and antioxidant activities were more positively correlated in ungerminated varieties than in germinated ones. Sorghum grains with pigmented testa layer, chestnut color glumes, and red plants had higher contents, larger diversity of phenolic compounds, and higher antioxidant activities than other sorghums. Some red sorghum varieties had higher antioxidant activities (30-80 mumol of Trolox equiv/g) than several sources of natural antioxidants from plant foods. Among varieties used for "to", "dolo", couscous, and porridge preparation, the "dolo"(local beer) varieties had the highest average content and diversity in phenolic compounds as well as the highest antioxidant activities. The biochemical markers determined are useful indicators for the selection of sorghum varieties for food and agronomic properties.     

Wastewater Reuse for Alfalfa Production in the Gaza Strip

Geography, population growth, and politics combine to make the Gaza Strip a worst-case scenario for water resource planners. Potable water sources are shrinking while at the same time, the proportion of potable water used for irrigation is increasing. To assess whether water from wastewater treatment plants could be safely used for irrigation, this study collected 51 treated wastewater, 51 sludge, 44 soil, 30 alfalfa, and 24 oranges and lemon samples and analyzed the samples for major and trace elements. Both Inductively Coupled Plasma - Optical Emission Spectroscopy (ICP/OES) and X-ray fluorescence (XRF) were used for the determination of Ag, Al, As, B, Ba, Br, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Na, Ni, P, Pb, Rb, Se, Sr, Zn, Zr, Th, and U in digested and solid samples, respectively. Treated wastewater characteristics showed a very good agreement with the guidelines of many developed countries. Moreover, none of the tested parameters in soil showed concentrations exceeding their corresponding background values. For alfalfa, both ICP/OES and XRF showed Zn concentrations in leaves (36–42 mg/kg, respectively) higher than in root (19–31 mg/kg, respectively). The Cu showed also the same trend as Zn. No significant variation was observed between the concentrations of Cr and Mn in plant parts; concentrations of Co and Pb were two times higher in roots than in leaves and stems. The findings confirm that treated wastewater is safe to use for irrigation in Gaza. Collecting and reclaiming this water can contribute to wise use of each drop of water available.     

Leaf gas exchange and water-use efficiency of dry-land wheat genotypes under water stressed and non-stressed conditions

The objective of this study was to determine drought tolerance characteristics of dryland wheat genotypes based on leaf gas exchange and water-use efficiency in order to identify promising genotypes for drought tolerance breeding. Physiological responses of ten genetically diverse wheat genotypes were studied under non-stressed (NS) and water stressed (WS) conditions using a 2?×?10 factorial experiment replicated 3 times. A highly significant water condition?×?genotype interaction (P?<?0.001) was observed for photosynthetic rate (A), ratio of photosynthetic rate and internal CO₂ concentration (A/C_i), ratio of internal and atmospheric CO₂ (C_i/C_a), intrinsic (WUE_i) and instantaneous (WUE_inst) water-use efficiencies suggesting genotypic variability among wheat genotypes under both test conditions. Principal component analysis (PCA) identified three principal components (PC’s) under both test conditions accounting for 84% and 89% of total variation, respectively. Bi-plot analysis identified G339 and G344 as drought tolerant genotypes with higher values of A, T, gs, A/C_i, WUE_i and WUE_inst under WS condition. The current study detected significant genetic variation for drought tolerance among the tested wheat genotypes using physiological parameters. Genotypes G339 and G344 were identified to be drought tolerant with efficient A, T, gs, A/Ci and water-use under water stressed condition.     

Phenol-formaldehyde resin curing and bonding under dynamic conditions

Summary To better understand the curing and bonding behavior of phenol-formaldehyde (PF) resin under dynamic conditions, flakeboards were manufactured either by conventional pressing at 7% or 12% mat moisture content or by steam injection pressing with 10 or 20 seconds steaming duration. Resin-impregnated glass-cloth samples and lap-shear tension specimens were embedded in the core of each flakeboard. After the flakeboards were pressed for various periods of times, the samples and specimens were quickly retrieved. The degree of resin cure was determined on the resin-impregnated glass-cloth samples by dynamic mechanical analysis. The bond strengths were measured from the lap-shear tension specimens on a mechanical testing machine. The results of resin curing and bonding were then correlated to the performance of the resin-bonded boards, which were evaluated by internal bond, modulus of rupture, modulus of elasticity, and thickness swelling. Resin curing and lap-shear bonding did not proceed simultaneously. In conventional pressing, the mat moisture content (MC) at 12% favored resin curing, but slightly retarded lap-shear bonding, as compared to 7%MC. In steam injection pressing, the rates of resin curing and lap-shear bond strength development were much faster for 20 seconds than for 10 seconds of steaming duration. Longer press times were needed to obtain boards with maximum strength in the 12%MC conventional pressing and the 20-s steam duration steam injection pressing than in those conditions where moisture content was lower or steam time was less. The need for longer press times must be attributed to higher internal vapor pressures and/or lower wood and resin component strengths, rather than to incomplete cure or bonding.This material is based on work supported by the Ministry of International Affairs, Quebec Government, the Natural Sciences and Engineering Research Council of Canada, and Laval University (Quebec City). The work was also supported by the U.S. Department of Agriculture under research joint venture agreement FP-92-1835     

Nutrient stocks of short-term fallows on a high base status soil in the humid tropics of Papua New Guinea

In order to understand nutrient dynamics in tropical farming systems with fallows, it is necessary to assess changes in nutrient stocks in plants, litter and soils. Nutrient stocks (soil, above ground biomass, litter) were assessed of one-year old fallows with Piper aduncum, Gliricidia sepium and Imperata cylindrica in the humid lowlands of Papua New Guinea. The experiment was conducted on a high base status soil (Typic Eutropepts), and in Papua New Guinea such soils are intensively used for agriculture. Soil samples were taken prior to fallow establisment and after one year when the fallows were slashed and above ground biomass and nutrients measured. The above ground and litter biomass of piper was 13.7 Mg dry matter ha^-1, compared to 23.3 Mg ha^-1 of gliricidia and 14.9 Mg ha^-1 of imperata. Gliricidia produced almost 7 Mg ha^-1 wood. Total above ground biomass returned to the soil when the fallows were slashed was the same for piper and gliricidia (8 Mg ha^-1). Gliricidia accumulated the largest amounts of all major nutrients except for K, which was highest in the above ground piper biomass. Imperata biomass contained the lowest amount of nutrients. The largest stocks of C, N, Ca and Mg were found in the soil, whereas the majority of P was found in the above ground biomass and litter. Almost half of the total K stock of piper and gliricidia was in the biomass. During the fallow period, soil organic C significantly increased under gliricidia fallow whereas no net changes occurred in piper and imperata fallows. The study has shown large differences in biomass and nutrient stocks between the two woody fallows (piper, gliricidia) and between the woody fallows and the non-woody fallow (imperata). Short-term woody fallows are to be preferred above grass (imperata) fallows in the humid lowlands of Papua New Guinea because of higher nutrient stocks.