Surface Soil Horizons Research Articles

The effects of direct drilling, shallow cultivation and ploughing on some soil physical properties in a long-term experiment on spring barley

SummaryPhysical measurements were made on the soil of a long-term cultivation experiment comparing direct drilling, tine cultivation and mouldboard ploughing for spring barley to investigate possible reasons for differences in yield. The soil was a typical argillio brown earth, approximately 90 cm of sandy clay loam topsoil and clay loam subsoil overlying magnesian limestone. For the three periods 1971–4, 1975–7 and 1978–80 the mean grain yields were marginally lower after direct drilling than after shallow cultivation or ploughing. There was an average decline in yield of 1·33 t/ha from the first to the last period, the decline being greater for direct drilling than the other two tillage systems. Although the surface horizon (0–5 cm) of direct-drilled soil had a higher content of organic matter than the ploughed, this did not increase the stability of the aggregates. Slaking tests had shown the soil to be inherently unstable and likely to suffer from structural problems. After the first 3 years bulk density of direct-drilled soil (0–15 cm) increased markedly toca.l·5 g/cm8and then remained relatively stable. In the ploughed soil, density increased steadily over the period to an average value of co. 1·45 g/cm8. Tine cultivation to 7–8 cm reduced cone resistance values in the surface compared with direct-drilled soil but below 15 cm there were no significant differences. Ploughing gave significantly lower values than direct drilling to a depth of 30 cm. Measurements of pore sizes in direct-drilled and ploughed soil were highly variable with few significant differences. Mean air capacity values (1978–80) tended to be lower in direct-drilled than in ploughed topsoil particularly for plots direct drilled after 7 years of deep tine cultivation. A limited number of root measurements in 1978 and 1980 showed that the length of root per unit of ground area was much less after direct drilling than after ploughing. Shallow cultivation, surprisingly, gave most root with a greater proportion of the root system below 20 cm than in the other two treatments. The classification of this soil according to its suitability for direct drilling cereals is discussed.

Alfalfa Production Improved by Shallow Drains on Marine Sediments

ABSTRACT ALFALFA responded favorably to shallow subsurface drainage at three spacings compared to no drainage on a silty clay loam marine sediment under cool humid climate field conditions over a four year period. There were four replications each of four drain spacings (none, 3, 6, and 12 m) of 7.5 cm diameter drain tubing at 60 cm depth. Soil water content at 30 cm depth intervals to 120 cm and water-table depths were measured to characterize the seasonal soil moisture regimes. Total hay yields on the drained plots during four growing seasons with three intervening winters were significantly higher than without drainage. Alfalfa persistence as measured by crop botanical analysis and live crown counts was also greater on the drained treatments. Favorable crop response due to subsurface drainage can be attributed to a change in the rooting environment. Water tables were lowered by drains which improved the soil water regime in the upper 60 cm of the root zone. Aeration or oxygen diffusion rate in the soil surface horizon was enhanced by drainage during early spring. Subsurface drains 60 cm deep and spaced at 12 m in these slowly permeable soils will provide suitable conditions for alfalfa growth.

Characteristics of soil profiles affected by smelting of nickel and copper at Coniston, Ontario, Canada

Soil profiles were examined, described and sampled by horizons in various geomorphic positions along a transect originating at the Coniston smelter and extending in a southeasterly direction for approximately 12 km. The samples were then analyzed to determine particle-size distribution, pH, organic carbon and five heavy metals. Within the study area, elevated levels of nickel, copper and iron were found with maximum total concentrations of 1.2, 0.97 and 20.0%, respectively. Manganese and zinc did not occur in above-normal concentrations. The pH values of the soils were depressed with levels as low as 2.4. Near the smelter, erosion from soils on slopes has transferred materials into lower lying areas, thereby rearranging the areal distribution of nickel, copper and iron. Although the surface soil horizons along the entire transect have above-normal concentrations of these elements, only within the eroded area is there marked variability in their vertical distribution.

Quantitative comparison of the nitrogen-containing pyrolysis products and amino acid composition of soil humic acids

Pyrrole and acetonitrile, major pyrolysis products of soil humic substances, vary characteristically in abundance with the degree of humification of the organic matter in the soil. Their origin, however, is uncertain because of the large amount of unidentifiable soil nitrogen. A quantitative relationship between amino acid composition and pyrrole and acetonitrile abundances has been established by Curie-point pyrolysis-gas chromatography of a group of test proteins, using polystyrene as an internal standard. The pyrolysis yields of these products from three humic acids extracted from the surface horizons of Scottish brown forest soils (Cambisols or Ochrepts) were entirely accounted for by the known hydrolysable amino acid content and composition, and the products were related to individual amino acids. The peptide amino acid was also found to be the overall source of the aromatic pyrolysis products toluene, phenol and p-cresol.

Radiata pine residue management and its implications for site productivity on sandy soils

Summary Litter and logging residue retained in situ as a mulch has several beneficial aspects that can assist in maintaining the productivity of radiata pine (Pinus radiata D. Don) plantations on sandy soils in the Mt Gambier region of southern Australia. These benefits include the conservation of soil moisture, conservation of nutrients, protection of soil, and provision of a more favourable environment for root development in the surface soil horizons. The maintenance of site fertility by the addition of fertilisers is discussed and compared in both ‘burn’ and ‘non-burn’ situations. Mulching the litter and logging residue is operationally feasible and is an option that should be considered by plantation managers when re-establishing radiata pine, particularly on soils of low to moderate fertility.

Stratigraphy and 14C Dating of two Earth Hummocks, Jotunheimen, South Central Norway

Two types of periglacial earth hummock are recognized and their stratigraphy is discussed in terms of the origin of organic material contained within them. In one type of hummock this is considered to be derived solely from the soil surface horizon by cryoturbation processes, while in the other type, organic material bruied in situ by sediment derived from upslope erosional processes is also present. Samples of subsurface organic material have been 14C dated in order to investigate the timing of hummock activity. These results are discussed in the context of Holocene climatic change, although only limited climatic inferences can as yet be made.

Characterizing Unsaturated Hydraulic Conductivity of Western Kentucky Surface Mine Spoils and Soils

AbstractA large‐scale laboratory infiltrometer system was used to determine infiltration characteristics of “reconstructed” surface mine spoil and soil horizons. Soil water characteristic curves were determined using the Brooks‐Corey and the Gardner procedures and developed based on desorption tensiometer data. Unsaturated hydraulic conductivity values were determined using the “plane of zero flux” procedure and compared with predictions resulting from models described by Campbell, Burdine, and Mualem for situations involving reconstructed soil and spoil materials. There was generally good agreement between the models and excellent agreement between Campbell's predictions and plane of zero flux results. Both the Gardner equation and the Brooks‐Corey equation gave good estimates of the soil water characteristic curves for the materials. The physical significance of the parameters θr and ψe, when determined by statistical procedures, appears very questionable. In this study, the final steady‐state infiltration rate appeared to be a good estimate of the hydraulic conductivity at apparent saturation.

Eolian origin of quartz and mica in solls developed on basalts in Northwestern Kyushu and San-In, Japan

Abstract Quartz and mica contents were determined as a function of particle size of soils over quartz and mica-free basalts in northwestern Kyushu and San-in. The contents of both minerals were much higher in the surface soil horizons than in the lower horizons. Quartz particle size distribution (predominantly 2 to 53 μm) and surface morphology (chip or shard, not euhedral) which are similar to those in the north central Pacific pelagic sediments and Hawaiian soils, indicated that quartz is added as aerosolic dust and loess carried by the circumpolar Westerly Winds from Asian semi-arid and arid regions. Close proximity to the eolian sources was deduced by somewhat coarser texture of the present soil quartz. Lower surface soil quartz content, relative to that in the Hawaiian soils was interpreted as indicating a younger landscape age caused by intensive denudation. The covariant relation between the quartz and miea eontents of soils may suggest that at least a portion of the micaceous minerals and quartz i...

Genesis of a So‐called Ferrolysed Soil of Bangladesh

AbstractIt was postulated by Brinkman (1970) that low clay contents in the surface horizon of paddy soils (Planosols) are caused by clay destruction through ferrolysis. In an effort to test this, a rice profile from the site of Brinkman's Eutric Planosol (Salna, Bangladesh) and a neighbouring forest soil (Dystric Cambisol) of the same parent material and particle‐size distribution (Bhawal National Park) were investigated. The micro‐structure, particle‐size distribution, mineral contents, pedogenic oxides, contents of Zr, Ti and K of the fine earth and individual fractions and also the exchangeable ions were studied.The clay fraction of both soils were chloritised by interlaying of hydroxy‐Al in the smectite interlayers in the surface horizons and got stabilized. As a result CEC showed some decrease. The forest profile has a loose and uniform brown‐yellow surface horizon and is relatively rich in coarse sand at 62–75 cm depth which might be caused by a strong termite activity as observed during sampling. On the contrary, the frequent and alternate reducing and oxidizing conditions have resulted in gleying the top soil and forming iron‐oxide films on the surface of aggregates during dry periods in the paddy soil.An evaluation of all results shows that a little clay destruction and an enrichment of silt in the top soil through vertisol formation and also through primary parent material stratification were the reasons for low clay content in epipedons. In forest soil there was a little clay migration, while the epipedon of the paddy soil had low clay in addition, because of selective erosion during heavy rains following the destruction of structure by puddling.The ferrolysis as a dominant factor for a clay‐low epipedon is improbable, because the clay loss of the neighbouring forest soil can not be explained by ferrolysis.

Distribution of Phosphorus in Soils Irrigated with Municipal Waste‐Water Effluent: A 5‐Year Study

AbstractThis 5‐year field study of phosphate (PO4) management was conducted on Waukegan silt loam (Typic Hapludoll) soil, which has a water table at about the 140‐ to 150‐cm depth. The results of municipal waste‐water irrigation, with annual application means of 0, 126, and 237 cm, indicates that in terms of PO4 management, soils receiving comparable quantities of PO4 from either waste water or mineral fertilizer (rates for good crop management) behaved in similar manner. Sharp increases in organic‐P were found in the surface horizon of soil receiving effluent, while increased levels of available‐P were observed to a depth of 60 cm in the high‐treatment area (mean annual P addition of 160 kg/ha). Phosphate‐adsorption studies, with the aid of the Langmuir equation, showed that the adsorption power of soil from the higher effluent application rates (237 cm/year) had been reduced. This was substantiated by higher P concentrations (0.01 vs. 0.07 mg/liter) observed in soil water at the 60‐cm depth of the high‐treatment areas. These observations were fitted into a simplified model that described the fate of effluent PO4 applied to soil.

Late quaternary drift deposits of north central Nigeria examined by scanning electron microscopy

Samples of drift were studied by mechanical analysis and scanning electron microscopy of individual grains and compared with nearby fixed dunes and present-day pedisediment. Results indicate that the drift is well sorted and has the textural characteristics of a loess (modal grain size + 4 − + 5 Ø, 62-31 μm), this differs markedly from the fixed dunes (modal grain size + 2 − + 3 Ø, 250-125 μm), SEM micrographs show that the drift contains grains with a wide variety of morphologies, although they are predominantly angular to sub-angular with only limited evidence of abrasion by aeolian and/or fluvial transport and some ovegrowths of secondary silica. This suggests that much of the drift material is of local origin, and was deposited by aeolian reworking of alluvium and coarse surface soil horizons when sand dunes were forming further north. It is envisaged that concomittant with aeolian activity was periodic reworking of the drift by slopewash associated with individual storms and a wet season of reduced duration and intensity.

Fertilisation azotée en forêt de pin gris (Pinusbanksiana). I. Cheminement des engrais dans le sol

Six nitrogen fertilizers (urea, sulfur-coated urea, urea-formaldehyde, ammonium nitrate, ammonium sulfate, and ammonium nitrate) were individually applied, either in fall or in spring, at a rate of 224 kg N/ha and compared for nitrogen retention in the different horizons of a podzol under jack pine. Despite its susceptibility to nitrogen losses through ammonia volatilization, urea was by far, among readily available nitrogen fertilizers, the one whose nitrogen is best retained in soil surface horizons. Retention varied with weather conditions that prevailed immediately after fertilizer application. With the other fertilizers used, nitrogen retention followed this order: ammonium sulfate > ammonium nitrate > calcium nitrate. After four seasons, about 50% of the nitrogen applied as sulfur-coated urea and urea-formaldehyde was still found in its original form. Ammonium sulfate is next to urea among the recommended nitrogen sources for similar jack pine sites, considering that fertilizers with nitrate are prone to leaching and the sulfur-coated urea and urea-formaldehyde used presented problems of nitrogen availability.

Detection of carbonyl sulfide among gases produced by the decomposition of cystine in paddy soils

Abstract Most of the sulfur in the surface horizons of soil in humid and semiarid regions occurs in organic form (1). A significant fraction of the organic S in soils and most of the organic S in plant residues is in the form of S-containing amino acids (2, 3). Also, it is known that some microorganisms can degrade S-containing amino acids with the formation of volatile S compounds (3–5).

A theoretical analysis of interflow of water through surface soil horizons with implications for movement of chemicals in field runoff

Steady interflow of water in the near‐surface saturated soil horizons, which are the important nonpoint sources of applied agricultural chemicals appearing in field runoff, is investigated theoretically. Analytical solutions are obtained for some relevant cases of interflow in a sloping layered soil having a subsoil of lower permeability. Analysis is made for the effect of the relative permeability of the subsoil and of the depth of the subsoil above an impermeable base varying from zero to infinity, in relation to different ratios of slope length to soil profile depth. Solutions and analyses are also extended to a case where flow through the topsoil is saturated and steady, but where the subsoil is still accepting a constant downward flux of water uniformly over all its area. The solutions are for a rectangularly bounded, tilted flow medium; but for long slopes the details of the flow medium boundaries at the top and bottom ends should have negligible effects on overall flow. The results show that the interflow through each horizon of a layered soil profile can be approximated by a one‐dimensional Darcian flow parallel to the slope, if the ratio of slope length to soil profile depth is greater than about 6 to 10. This extends the finding reported earlier in the literature for a uniform soil. For an extreme case of a sloping soil with a semi‐infinitely deep subsoil on an impermeable base, the interflow through the topsoil, if it is highly conductive compared to the subsoil, can still be treated as a one‐dimensional flow. For such cases, the movement of soil chemicals with interflow can be described as a one‐dimensional miscible displacement process. A uniformly constant downward flux of water into the subsoil decreases interflow through the topsoil. The extent of the decrease depends upon the land slope and the relative conductivity of the subsoil. Of even greater significance for chemical transport is the finding that the cross section of the topsoil through which the interflow traverses and picks up its chemical load is drastically reduced by downward leakage, even when the subsoil conductivity is two orders of magnitude smaller than that of the topsoil. A simplified prediction of this region of interflow is deduced from the results. By representing this wedge‐shaped area by an equivalent rectangle, the chemical movement, for a first‐order estimation in field application, may still be approximated as a one‐dimensional displacement.

Late quaternary drift deposits of north central Nigeria examined by scanning electron microscopy

Samples of drift were studied by mechanical analysis and scanning electron microscopy of individual grains and compared with nearby fixed dunes and present-day pedisediment. Results indicate that the drift is well sorted and has the textural characteristics of a loess (modal grain size +4 − +5 ø , 62 – 31 μ m), this differs markedly from the fixed dunes (modal grain size +2 − +3 ø , 250 – 125 μ m), SEM micrographs show that the drift contains grains with a wide variety of morphologies, although they are predominantly angular to subangular with only limited evidence of abrasion by aeolian and/or fluvial transport and some ovegrowths of secondary silica. This suggests that much of the drift material is of local origin, and was deposited by aeolian reworking of alluvium and coarse surface soil horizons when sand dunes were forming further north. It is envisaged that concomittant with aeolian activity was periodic reworking of the drift by slopewash associated with individual storms and a wet season of reduced duration and intensity.

PODZOL DEVELOPMENT NORTH OF LAKE HURON IN RELATION TO GEOLOGY AND VEGETATION

The morphological expression of podzolization in four Humo-Ferric Podzols increased in a northerly direction over a distance of approximately 74 km from the north shore of Lake Huron. The transect coincided with changes in both geology and vegetation. All the soils were developed in coarse-textured acid tills whose composition was not significantly different to explain the observed variations in soil morphology. Using quartz as an internal standard, the order of mobility from surface horizons was found to be Mg > Fe = Ca > Na = Al > K > Ti. Pyroxenes, amphiboles, chlorite and albite were the most easily weathered minerals. Protocatechuic, p-coumaric, gentisic and gallic acids were found to be the major phenolic acids in water extracts of soil surface horizons. The content of both phenolic acids and carbohydrates in surface horizons increased as the morphological expression of podzolization increased.

Preferential Clay Mineral Erosion from Watersheds in the Maumee River Basin

AbstractRunoff sediments and soil surface horizons from five small watersheds were characterized for clay mineralogy, particle size distribution, cation exchange capacity, and amorphous and free iron oxide content. The objective was to determine if preferential transport of clay minerals from these watersheds was occurring.Clay mineralogical analysis indicated runoff sediments contained higher concentrations of illite and expandables with lower concentrations of vermiculite and quartz relative to watershed soils. The differences were attributed to preferential transport of fine clays from the soil surface.Runoff sediments contained an average of 18.4% more clay than soil surface horizons. Additionally, the total clay fraction of sediments contained an average of 10.1% more fine clay. Cation exchange capacity increased from 41 meq/100 g for soil clay fractions to 46 meq/100 g for sediment clay fractions due to the increased fine clay content. Both amorphous and free iron oxide contents were lower in the clay fractions of runoff sediments than in the clay fractions of soil Ap horizons.

Dissolution and Stability of Biogenic Opal

AbstractBiogenic opal isolated from leaves of seven deciduous trees, one grass species, and surface horizons of forest and grassland soils, was examined for dissolution in hot and cold distilled water. In cold water, silica dissolution was torpid and Si concentrations remained nearly constant through a 4‐week equilibration period; Si values for all but one opal specimen were between < 0.5 and 2 µg Si/ml. Dissolution over a 5‐hour period in distilled water at 90°C yielded the following Si concentrations (µg Si/ml): 4 to 5 for tree‐leaf isolates; 1 to 8 for soil isolates, 83 for the grass isolate, 0.5 for quartz, and 110 for silica gel. Opal dissolution is greater for 2–5 µm soil isolates than 5–20 µm isolates. Biogenic opal isolated from soils and deciduous tree leaves is much more stable than previously considered and exhibited Si dissolution similar to that reported for geologic opal. Further work is needed to clarify differences in opal solubilities between grass and forest origin.

MEASUREMENT OF THE MOBILITY OF SOIL COLLOIDS

SummaryA method is described for measuring the relative mobility (RM) of colloidal suspensions. It was used to assess the potential mobility of clay in the horizons of 12 profiles from Belgium, Bolivia, Brazil and India.The colloid from surface horizons of soil was always more mobile than that from deeper layers. The values of relative mobility differed between profiles and appeared to give a useful indication of potential clay migration under natural conditions.

Effects of humic and fulvic acids on release of fixed potassium

Release of potassium fixed by expanding silicate clays is considered of practical importance in soil fertility. Humic and fulvic acids are expected to play a definite role in liberating this fixed K, because of their chelating power, but not much is known in this respect. The following investigation was conducted to study release of fixed K by montmorillonite and illite, using humic and fulvic acids isolated from the surface horizon of a Cecil soil (Typic Hapludult, Red Yellow Podzolic soil) as extractants. For comparison, extraction was also done with 1 N neutral NH 4 -acetate, a mixture of 0.05 N HCl and 0.025 N H 2SO 4 or H 2 O. Supporting analyses of clays were carried out with X-ray diffraction to establish changes, if any, in crystal structure due to fixation, release of K, or adsorption of humic compounds. The results indicated that humic and fulvic acids released some of the K fixed by montmorillonite or illite. In terms of percentage of the total K fixed, 9 to 28% were released by the various extractants. The percentages K released by humic and fulvic acids were similar from both montmorillonite and illite, but based on absolute values, humic and fulvic acids extracted less K (mg/100 g) from illite than montmorillonite. Although statistically significant at the 5% level of probability, the capacity of humic compounds to liberate fixed K was not different markedly from those of NH 4 -acetate and the double acid mixture. Differences in pH of humic solutions had no influence on extraction of fixed K. X-ray diffraction analysis yielded curves showing an increase in spacing from 10.4 Å for K-montmorillonite to 13.2 Å as a result of extraction with the double acid mixture.