摘要:

SummaryMan's initial occupation of the British landscape was subject to broad physical constraints which are still apparent from archaeological evidence and place‐name interpretation. The influence of soils in initial settlement establishment is seen to be difficult to interpret several thousand years later as environmental conditions, including soils, have changed. Conversely, man's effect on the soils surrounding his settlements is evident through agricultural and other activities. These activities have increased in their impact with the passage of time. A combination of historical geography and soil studies shows man's interaction with the country's most basic resourc

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1978.tb02043.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SummaryThe relation between the steady‐state flow rate in horizontal columns of swelling soils and the pressure difference applied across the ends is derived for small flow rates. The slope of the curve representing the relationship at zero flow rate gives the value of the hydraulic conductivity corresponding to the initial water content (and hence to the average water content). The result is valid for hysteretic systems.The curves are concave to the pressure axis for published moisture characteristics. However, they can be convex for characteristics of a form that has not been reported but which does not violate known physical laws. A particular hydraulic conductivity/water content relationship leads to linear curve

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1978.tb02044.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SummaryThe statistical distributions of intercepted void and particle lengths along lines through beds of random close packed equal spheres are analysed. The structures are described by sets of sixteen conditional porosities. Data are presented for 21 different sphere diameters.The intercepted void and particle lengths are given for two sizes of spheres having diameters in the ratio 1:0.8. The results are not very different from those for equal spheres.The effect of data length on the accuracy of the conditional porosities is measured for four representative particle diameters. A method for calculating pore size distributions from the conditional porosities is presented.

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1978.tb02045.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SummaryImage analysis was used to investigate the variability of pore space in soil thin sections. Two fine‐textured soil profiles (or pedons) were sampled by inserting eight Kubiena tins (7.5 × 6 × 4 cm) in ledges at 50 cm depth. From each soil block three horizontal thin sections (7.5 × 6 cm) were made and photographed. Each photograph was then divided into nine ‘frames’ so that the voids in each of these frames could be measured using the Quantimet 720 Image Analysing Computer.The results show the variability of three specific pore‐space characters and the consequent need to sample a number of large thin sections from several sample blocks for each soil horizon to obtain estimates of sample means with suitabl

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1978.tb02046.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SummaryFour levels of mechanical compaction (C) and six levels of subsequent simulated rainfall (R) were applied in all combinations to soil samples at five levels of moisture content (M) in the laboratory. After treatment, the soils were air‐dried to give uniform surface moisture contents and the crust strength was determined with a downward‐acting penetrometer. Almost 90% of the variation in peak penetration force was accounted for by an equation containing terms in R, CR, CM and

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1978.tb02047.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SummaryContinuous hourly records of soil temperature were collected at 1, 5 and 20 cm, throughout two growing seasons, 1973 and 1974, under crops of spring barley in the east of Scotland. Measurements were obtained from three cultivation treatments, deep ploughing, normal ploughing and direct drilling, at two nitrogen fertiliser levels, 0 and 150kg/ha. Compared with ploughed soil, direct‐drilled soil had a higher surface reflection coefficient and a higher thermal diffusivity between 5 and 20 cm; overall, this resulted in lower heat sums (°C hours/day over 5 °C and 10 °C) in direct‐drilled soil at 1 cm and 5 cm during the first 20 days after sowing. The thermal regimes of normally and deeply ploughed plots were very similar. Nitrogen fertiliser caused significant lowering of soil temperature at all three depths in the latter half of the growing season, due to increased shading of the soil surface by the crop canopy. Some implications of these findings for cultivations for cereals are dis

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1978.tb02048.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SummaryTo simulate processes tending to raise the pH of soil near a plant root, a stack of moist HCO‐3saturated ion exchange resin papers was placed in contact with non‐calcareous soil of varying pH, containing HC1 + CaCl2in the soil solution. Changes in the concentration profiles of Ca2+, Cl‐and H+in the soil were followed. HCO‐3released from the resin in exchange for soil Cl‐reacted with the soil and raised its pH. Increases of up to 1 unit were measured near the interface. The zone of pH increase extended into the soil much less than the zone of chloride depletion. It was shown that Ca2+could accumulate near the interface in the absence of mass flow in this experiment

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1978.tb02049.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SummarySorption isotherms and heats of sorption of NH3gas on soils, Wyoming bentonite and silica gel were measured at 27 °C after preliminary drying at 22°‐290 °C. Sorption of NMe3was also measured on some of the materials.Sorption on soils was not very sensitive to change in drying temperature, even though soil water content was markedly affected. Sorption on bentonite was dependent on drying temperature because this affected ease of lamellar separation.The results suggest that under the conditions employed, NH3sorption on the English soils studied is predominantly due to its protonation at pH‐dependent charge sites and partly to co‐ordination with exchangeable Mg or Ca (but not Na or K). Sorption through mechanisms involving hydrogen bonding is apparently ne

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1978.tb02050.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SummarySuccessive extraction with Ca‐saturated sulphonated resin is used to remove potassium from soils. The kinetics of K‐release are analysed mathematícally to define three simultaneous rate processes by the amounts and rate‐functions associated with them. The diffusion coefficient (3 × 10‐19cm2sec‐1) calculated for the slowest process (suggested to be from the mineral matrix) is of the same magnitude as that for illitic clay minerals. The effect of K manuring on these parameters is evaluated from measurements on soils from the Nil and K‐fertilised plots of the Rothamsted Classical Experiments.Based on this analysis, a procedure is suggested for deriving from a smaller number of observations the amount of K a soil would release in a given time, and the contribution of each process to this amount is

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1978.tb02051.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SummaryYttrium and zirconium concentrations, taken as representative for the abundances of the heavy minerals xenotime and zircon in soils and stream sediments of the Schwarzach valley in eastern Bavaria, were found to be closely correlated, the Zr/Y ratio averaging 9.7 (r = 0.90 for 73 samples). The uniformity of this ratio ‐ despite considerable local variations of the individual concentrations—indicates its suitability for tracing back soils and sediments to the parent ro

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1978.tb02052.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY