Acid Parent Materials Research Articles

Inventory and assessment of pH in cropland and grassland soils in Germany#

AbstractBackgroundSoil pH is one of the key factors affecting soil fertility. For optimal plant growth on agricultural land, suitable liming management is recommended. The basis of appropriate soil pH management in agriculture is provided by recommendations on site‐specific optimum pH ranges and lime application.AimsThis study determined the current variability of soil pH of cropland and grassland in Germany, analysed the factors associated with this variability, evaluated pH management on German agricultural land and developed a national map of current pH values in agricultural soils.MethodsThe study mainly focused on the topsoil layers of 2197 cropland sites (0–30 cm) and 812 permanent grasslands sites (0–10 cm) in the German Agricultural Soil Inventory, but reports soil pH (CaCl2) down to 50 cm. Random forest models were applied to identify environmental and management factors related to soil pH and develop a map of pH values in agricultural topsoils in Germany. The current pH status of the sampled sites was classified in accordance with German lime requirement recommendations.ResultsThe soil pH of both land‐use types showed a bimodal distribution, with peaks at pH 6.1 and 7.3 for cropland and pH 5.0 and 7.1 for grassland. Soils with pH <5 were mainly found on sandy soils in northern Germany and acidic parent material in southern Germany. Alkaline soils predominated in central and southern Germany on loess and carbonate‐rich material. The carbonate content was the major factor explaining soil pH variability, but its effect was restricted to pH values >6. Only 35.4% of the cropland sites and 23.9% of the grassland sites were within the recommended optimum pH range. The percentage of sites below the recommended pH range was greater for grassland than for cropland (52.0% and 41.0%, respectively).ConclusionsSoil pH of German agricultural land is influenced by natural factors and pH management. The first national inventory of soil pH showed that many agricultural soils exhibited pH values lower than those recommended. More conscientious pH management could help improve soil fertility and crop yield. This should be based on the regular topsoil pH analysis conducted by most farmers every five years, together with the determination of plant‐available potassium and phosphorus in soils.

Geogenic CO2 affects inorganic soil properties and the composition of soil organic matter in physical fractions

The presence of geogenic CO2 has been recently identified as a soil-forming factor in soil on mofette sites. Topsoil samples (with a maximum CO2 concentration of 52% at 10 cm depth) were studied along a transect on a mofette site in the NW Czech Republic to further understand the processes within soil and the soil properties induced by CO2 in the soil atmosphere. Geogenic CO2 negatively affected the cation exchange capacity, the ratio of exchangeable Ca and Mg, and the total contents of Al, Mg and Mn. No effect was detected on a chemical index of weathering and the mineralogical composition of the clay fractions, which might be explained by the acidic parent material and the progress of soil development. Diffuse reflectance infrared spectroscopy indicated that the composition of particulate soil organic matter was partially affected by CO2 concentrations: the higher the CO2 concentrations, the smaller the extent of oxidative transformation and the smaller the abundance of carboxyl groups. In the clay fractions, stabilisation of transformed soil organic matter (SOM) was promoted by exchangeable Al. This study quantifies, for the first time, the correlation between geogenic CO2 and several inorganic soil properties and the composition of SOM in physical fractions.

SOIL PROPERTIES OF THE ALLUVIAL PLAIN AND ITS POTENTIAL USE FOR AGRICULTURE IN DONGGALA REGION, CENTRAL SULAWESI

Agricultural lands of Donggala region are extensively distributed in alluvial plain. However, information on soil properties and fertility constraints has not been known in detail. An investigation of soil resources was conducted in September 2003 and December 2004 to characterize surface soil properties of alluvial plain and to evaluate soil fertility constraints. For this study, 55 representative soil profiles consisting of 187 soil samples were selected for physical, chemical, and mineralogical analyses. The soil profiles were classified as soil groups of Ustifluvents, Haplustepts, Eutrudepts, and Endoaquepts. All the soil physical and chemical data were calculated as weighted average based on top 30 cm soil layer analyses. The results showed that soil texture ranged from sandy loam to loam. In ustic moisture regime, the average pH was neutral (7.0-7.2), but in udic moisture regime it was slightly acid (5.5-6.2). In all soil groups, the organic carbon content was very low to low (0.58-1.44%), P retention was very low (3-18%), and soil cation exchange capacity (CEC) was very low to low (9-14 cmol(+) kg-1). In contrast, all the soil groups showed very high content of potential phosphate (81- 118 mg P2O5 100 g-1) and potassium (338-475 mg K2O 100 g-1), but the available phosphate and potassium were 16-47 mg kg-1 P and 0.18-0.35 cmol(+) kg-1, respectively, which were considered to be low to medium range. The very high P2O5 and K2O were probably derived from weathered mica-schist and granite rocks, but low exchangeable K was probably due to K fixation. The sand mineral fraction was composed of relatively high (> 20%) weatherable minerals of acid parent materials, such as orthoclase and sanidine, while the clay mineral was composed of smectite and illite. The low soil-CEC, low organic matter, and exchangeable K contents were the main soil fertility constraints. Therefore, soil management should be directed to organic matter application to increase soil carbon content, CEC, and nutrient availability. Fertilizer recommendation for wetland rice and several upland crops is suggested based on the soil properties.

SOIL PROPERTIES OF THE ALLUVIAL PLAIN AND ITS POTENTIAL USE FOR AGRICULTURE IN DONGGALA REGION, CENTRAL SULAWESI

Agricultural lands of Donggala region are extensively distributed in alluvial plain. However, information on soil properties and fertility constraints has not been known in detail. An investigation of soil resources was conducted in September 2003 and December 2004 to characterize surface soil properties of alluvial plain and to evaluate soil fertility constraints. For this study, 55 representative soil profiles consisting of 187 soil samples were selected for physical, chemical, and mineralogical analyses. The soil profiles were classified as soil groups of Ustifluvents, Haplustepts, Eutrudepts, and Endoaquepts. All the soil physical and chemical data were calculated as weighted average based on top 30 cm soil layer analyses. The results showed that soil texture ranged from sandy loam to loam. In ustic moisture regime, the average pH was neutral (7.0-7.2), but in udic moisture regime it was slightly acid (5.5-6.2). In all soil groups, the organic carbon content was very low to low (0.58-1.44%), P retention was very low (3-18%), and soil cation exchange capacity (CEC) was very low to low (9-14 cmol(+) kg-1). In contrast, all the soil groups showed very high content of potential phosphate (81- 118 mg P2O5 100 g-1) and potassium (338-475 mg K2O 100 g-1), but the available phosphate and potassium were 16-47 mg kg-1 P and 0.18-0.35 cmol(+) kg-1, respectively, which were considered to be low to medium range. The very high P2O5 and K2O were probably derived from weathered mica-schist and granite rocks, but low exchangeable K was probably due to K fixation. The sand mineral fraction was composed of relatively high (> 20%) weatherable minerals of acid parent materials, such as orthoclase and sanidine, while the clay mineral was composed of smectite and illite. The low soil-CEC, low organic matter, and exchangeable K contents were the main soil fertility constraints. Therefore, soil management should be directed to organic matter application to increase soil carbon content, CEC, and nutrient availability. Fertilizer recommendation for wetland rice and several upland crops is suggested based on the soil properties.

Pedogenic Transformation of Phosphorus during Paddy Soil Development on Calcareous and Acid Parent Materials

Soil Sci. Soc. Am. J. 77:2078–2088 doi:10.2136/sssaj2013.01.0033 Received 23 Jan. 2013. *Corresponding author: (glzhang@issas.ac.cn). © Soil Science Society of America, 5585 Guilford Rd., Madison WI 53711 USA All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher. Pedogenic Transformation of Phosphorus during Paddy Soil Development on Calcareous and Acid Parent Materials Pedology

Assessing the effects of Cu and pH on microorganisms in highly acidic vineyard soils

Because of the use of agricultural land for wine production and the frequent use of copper (Cu)‐based fungicides, Cu concentration has been increasing in soils in many parts of the world. In vineyards with acid parent materials, low soil pH may also encourage Cu toxicity, but it is common to use lime in order to increase the soil pH and improve crop yields. Thus, vineyard soils may have large variations in pH, which will affect the microbial communities, making it difficult to isolate possible toxic effects of Cu on soil microbes. Here, analyses of phospholipid fatty acid (PLFA) patterns and pollution‐induced community tolerance (PICT, using leucine incorporation) were used to study the effect of Cu accumulation at small to medium concentrations in acid soils (pH 4.0–5.8) in vineyards with different land‐use history (young, old and abandoned vineyards). The results suggested that soil pH played a dominant role in determining the composition of the microbial community of the soils. Only a small effect of soil Cu could be detected and the effect on microbial community composition was much less than the pH effect. PICT analysis suggested that bacterial communities in old vineyards were more tolerant of Cu than those in the abandoned vineyards. However, increased PICT (Cu tolerance of the bacterial community) was not directly correlated with Cu concentration in the soils. Instead, the estimated Cu tolerance was significantly correlated with soil pH.

Soil carbon and nutrient accumulation under forest plantations in southern Rwanda

Tree and soil interactions may result in changes in soil carbon and nutrient contents. Forest plantations made up of monodominant stands of 17 different species, some native and some exotic to Rwanda, as well as a stand with mixed native tree species were investigated. Biosequential sampling was used followed by basic soil chemical analyses. Results revealed that the plantation species composition influenced the soil chemical properties. Total soil C and N, C: N ratio, available P, pH, and cation exchange capacity (CEC) differed significantly between plantation stands of different species (P < 0.001, N = 54). Increases in the levels of soil C, total N, CEC and base saturation (BS) were observed mainly in mixed native species (MNS), Polyscia fulva, Casuarina equisetifolia andEucalyptus saligna. The pH declined slightly in soil beneath some Eucalyptusspecies treatments and increased in others. The high nutrient uptake by fast-growing trees and the acidic parent material were involved in the acidification process. The findings suggest that the species used in afforestation maintain soil fertility and protect the environment. It is recommended that afforestation of abandoned and less productive lands in Rwanda should utilize fast growingEucalyptus species in combination with agroforestry and native species in order to maintain or improve soil chemical properties. Key words: Afforestation, base saturation (BS), cation exchange capacity (CEC)forest plantation, soil carbon, total N, Rwanda

Evaluation of the Sensitivity of European Soils to the Deposition of Acid Compounds: Different Approaches Provide Different Results

Analysis of the sensitivity of soils to acidification caused by the deposition of atmospheric pollutants has been one of the major scientific issues in Europe during the past few decades. In the present study, critical loads of acid deposition were calculated using the most accurate datasets available at present for European soils, by the “Simple Mass Balance” method. The results show that the soils most sensitive to acid deposition are Histosols, Cryosols and Podzols in cold areas in northern countries, followed by Lithic and Haplic Leptosols (Dystric) developed on acid parent materials. The highest critical loads corresponded to soils developed over calcareous rocks and soils in areas subject to high precipitation, even those dominated by poorly weatherable primary mineral. In the latter case critical alkalinity leaching is the main variable that determines the value of critical loads, because of the buffering action of the dissolution of aluminium compounds. The results were compared with those obtained by the Stockholm Environmental Institute in the same area, but with a different method of analysis. It was found that the results are highly dependent on the method used to perform the analysis.

Acidification of a meadow chernozem (Luvic Pheozem) soil in the trans-Tisza region

Soil acidity is common in all regions where the soils developed on parent materials with low base content and/or the amount of precipitation is high enough to leach appreciable amounts of bases from the surface layers. Since the 1970s more and more data indicated that soil acidification is not confined only to the soils on wet areas which were developed on acidic parent material (Sipos-Patocs, 1975; Debreczeni, 1994). After leaching the CaCOj the acid load of soil is buffered by the exchangeable cations. The neutral, slightly acidic soils are especially sensitive to acidification. On slightly acid soil the same acid load caused much bigger pH decrease than on a strongly acid one (Zsigrai, 1995).

Podzol formation in sandy soils of Finland

Podzolization occurs quickly in acidic parent materials with addition of acidic litter from coniferous trees. This study was conducted to evaluate Podzol formation and estimate lengths of time required to meet morphological and chemical criteria of podzolic B horizon and spodic horizon in Finland. Soil color, organic C, ODOE, and extractable Al and Fe were measured in a seven-pedon chronosequence (230–1800 years) and four older pedons (8300–11,300 years). The bulk mineralogical composition of the BC and C horizons was uniform with quartz, plagioclase and K-feldspar as main components and amphibole, illite and chlorite as minor components. The fine (<5 μm) fraction of selected samples was primarily amorphous allophone-like material with some mixed-layered illite–vermiculite. All pedons in the study met the criteria for albic horizons according to the FAO–Unesco, World Reference Base (WRB) and Soil Taxonomy systems. According to the FAO–Unesco system, all pedons had spodic B horizons and were classified as Podzols. According to the WRB system, none of pedons of the chronosequence had spodic horizons, whereas the older pedons met the criteria for a spodic horizon. About 4780 years were required to form a spodic horizon according to the WRB system. The oldest pedon of the chronosequence and the older pedons had spodic horizons according to Soil Taxonomy, but the younger pedons failed to meet the spodic horizon criteria. About 1520 years were required to form a spodic horizon that met the color and organic C criteria of Soil Taxonomy, whereas it took about 4780 years to meet the required accumulation of Fe and Al. This study points out the discrepancy between the color criteria and the criteria reflecting the accumulation of Al, Fe and organic matter in the B horizon.

Species and life-forms composition of Mediterranean mountain pastures in two years of contrasting precipitation

Summary Twenty sites, representing different pasture types in NW Spain, were sampled with respect to their floristic composition and structural characteristics for two years of contrasting precipitation. The first year was characterised by a severe regional drought and the second year had normal precipitation. Four plant community types were identified by consensus classification techniques of plant species composition. These community types were associated with grazing regime, percentage cover of herbaceous vegetation, rocks and bare ground, and soil characteristics. One community type included mesic sites on acidic parent materials with low grazing, whereas the other three were all intensely grazed, and included either xeric or mesic sites on calcareous parent materials, or mesic sites on acidic parent materials. Species composition varied between years according to well defined directional trends within the intensely grazed communities. Compositional differences between calcareous and acidic pastures increased in the normal year. On average 49 to 73% of the species appeared only in one year. This high species turnover was also high when analysed separately for different life-forms, namely annuals, perennial grasses, perennial forbs and undershrubs. In spite of this, both the life-form spectrum, and the relative abundance of each life-form remained unaltered for each community type in both years. This suggests that such characteristics of the communities' structure are in equilibrium with habitat characteristics, as well as the existence of a deterministic structure in the grasslands studied.

Pedogenesis by clay dissolution on acid, low-grade metamorphic rocks under mediterranean forests in southern Tuscany (Italy)

Pedogenesis on acid, low-grade metamorphic rocks under well-developed forests was studied in the meso-mediterranean climatic zone. To that purpose three representative soil profiles on phyllite and sandstone under sclerophyllous oak, pine and heathland were selected. The major soil forming processes consisted of transformation of part of the K-mica (muscovite) to (hydroxy-interlayered) vermiculite and smectite, impoverishment both in major elements (Al, K, Mg and Fe) and fine particles, and redistribution of sesquioxides as organic complexes. These processes indicate clay hydrolysis under acid conditions and subsequent removal of solutes by lateral subsurface flow. The resulting impoverishment of the soil profiles could be mainly attributed to hydrolysis under acid conditions brought about by slow decomposition of organic matter. The proposed mode of pedogenesis deviates strongly from the current concept of fersiallitisation, and is probably restricted to acid parent materials in mediterranean climates where lateral removal of soluble weathering products is ensured throughout the largest part of the year.

Le système radiculaire dans les érablières du Québec. II. Le développement radiculaire en relation avec le microrelief et la roche mère

The root systems of two sugar maple groves, one on acidic parent material, the other on calcareous parent material, were studied in Quebec. The microrelief of both sites consisted of bumps and holes. Bumps represented 65% of the area. On acidic parent material, the roots &gt; 1 cm in diameter were more than 5 m long. On calcareous parent material, they rarely exceeded 4 m in length. These larger roots branched out into many smaller roots in all directions in the bumps, and in the upper soil horizons of the holes. In the acidic site, the rootlet mass was smaller (about 16 t•ha−1) than that observed in calcareous site (about 19 t•ha−1). In both sites, rootlet mass was higher in the bumps (14–17 t•ha−1) than in holes (2–4 t•ha−1). In bumps, 80 and 69% of these rootlets grew in the B horizons in acidic and calcareous sites, respectively. In the holes, rootlets were concentrated (&gt; 65%) in the F and Ah horizons. In the acidic site, rootlets &lt; 0,5 mm in diameter were longer, more entangled, and more densely packed (7–11 mg•cm−3) in the F and Ah horizons than in the B horizons (1–2 mg•cm−3); F and Ah horizons of the bumps also produced the highest density of rootlets &lt; 0,3 mm in diameter (about 50 and 20 mg•cm−3, respectively). In the other horizons of this site, as well as in all horizons of the calcareous site, the rootlets were short and developed in tufts. In the calcareous site, rootlets &lt; 0,3 mm in diameter were less abundant in the Ah horizons of bumps (about 10 mg•cm−3). This site contained more rootlets 1–2 mm in diameter than the acidic site.

Nitrogen and Carbon accretion on Ohio coal minesoils: Influence of soil-forming factors

Plantations of white pine ( Pinus strobus L.), tuliptree ( Liriodendron tulipifera L.), white ash ( Fraxinus americana L.) and black locust ( Robinia pseudoacacia L.), established in 1946 on ungraded calcareous, neutral or acid coal spoils, were sampled in 1976 for weight, carbon and nitrogen content of the forest floor, and for total N concentration in 4 depth increments of the underlying mineral soil. Minesoil characteristics were related to the following soil-forming factors: parent material (overburden), organisms (tree species) and relief (aspect and slope position). Forest floor weight was high under white pine on all parent materials and under black locust on acid parent material. Nitrogen content of the forest floor was highest on acid minesoil, as was total weight of N in the forest floor under all species except tuliptree. Although concentration of N in the forest floor was highest under black locust, total weight of forest floor N under pine exceeded that under locust on calcareous and neutral minesoils because of the much greater weight of forest floor under pine. C/N ration of forest floor was lowest under locust and on the acid minesoil. Total N concentration was highest at all depths in soils that formed under black locust: rate of decrease in total N concentration between the 0–5 and 5–15 cm depth increments was also greatest under black locust. Soils formed on calcareous parent material had higher total N concentrations at all depths than those formed on neutral or acid parent materials. We estimate that concentration of total N in the 0–5 cm horizon of calcareous minesoils has increased from 0.04 to 0.23% in the 30 years since tree establishment. The corresponding increase in the acid minesoils has been from 0.03 to 0.18%. Our results show that accretion of carbon and nitrogen on minesoils will be influenced both by overburden strata placed at the surface as parent material of the new soil and by tree species chosen for planting.

Distribution and genesis of red and yellow soils in the central subtropics of southeast China

In the subtropical climatic region of southeast China, which is influenced by the monsoon climate, red soils are widespread. According to the Chinese soil classification system the main soil groups are subdivided on the base of the degree of allitic weathering. This is mainly characterized by the SiO 2:Al 2O 3 molar ratio of the clay fraction (according to the Chinese classification the fraction <1μm). The weathering stage and soil properties are determined by the horizontal and vertical climatic zonation. In basin regions and lower altitudes of the mountains up to about 600 m above sea level Red Earths (central subtropics) and Lateritic Red Earths (south subtropics) are developed on silicate rocks. In higher altitudes these soils change to Yellow Earths with goethitic B-horizons. In order to obtain information of the main soil forming processes of typical and widely distributed soils in the central subtropical region, a Red Earth from Middle Pleistocene red sediments of a basin region (Quaternary Red Clay) and two profiles of a Red Earth - Yellow Earth toposequence from granite of the neighbouring mountainous region were investigated by morphological, mineralogical and pedochemical methods. During the youngest phase of morphodynamic stability the recent soils developed on pre-weathered parent materials (basin sediments and saprolite) containing kaolinite and gibbsite formed in ancient weathering periods. In the course of soil formation weathering proceeded with the transformation of halloysite to kaolinite and mica minrals through the stages illite and vermiculite to Al-chlorite. Pedochemical characteristics are dominated by an almost complete leaching of bases and a high Al-saturation of the sorption complex. The type and intensity of soil characteristics show a marked relation to the altitude of the sites, depending on differences in humidity and intensity of leaching processes. With increasing altitude the accumulation of organic substances and the neoformation of goethite and Al-chlorite increase, while with decreasing altitude the neoformation of hematite and intensity of lessivation increases. Bt horizons, which occur only in the Red Earths show that lessivation was an important process during soil genesis, although these soils developed from pre-weathered, acid parent materials. In Yellow Earths from different parent materials no indications to clay migration were found. According to the FAO legend the Red Earths in the area investigated belong to the soil unit of Ferric Acrisols and the Yellow Earths to the soil unit of Dystric Cambisols. It appears that the soil colour and the SiO 2:Al 2O 3 molar ratio of the clay fraction used as criteria for soil systematics cannot sufficiently indicate the degree of weathering, soil genesis and site properties.

Effects of acidic and basic parent materials on formation of some soils in Quebec (Canada)

Five profiles developed on basic or acidic parent materials were sampled in southern Quebec, Canada. Physical, chemical and mineralogical properties were determined. Among the three profiles developed on basic parent materials, one formed in disaggregated metabasalt whereas the two others developed in preglacial saprolites derived from the metabasalt, as indicated by till cover in a nearby area. In the lower part of the latter profiles, the saprolites had a loamy texture and the mineralogical plus chemical data indicated very slight changes with respect to the metabasalt. In these profiles, CBD-extractable Fe content was > 1% in most horizons, and the pyrophosphate-extractable Fe was generally higher in the Ah than in the B horizons. In the profiles developed on acidic till, CBD-extractable Fe was > 1% only in the B horizons, which also contained the maximum of pyrophosphate-extractable Fe. In the latter profiles, free Fe and Al sesquioxides were associated with the clay fractions whereas in the former profiles, one third of the Fe came from the sand and silt fractions. Chlorite was the dominant phyllosilicate in the basic material and it was transformed into interstratified minerals and smectite. Several hypotheses about smectite formation and distribution were discussed. In the profiles developed on acidic till, illite and chlorite were the major phyllosilicates and, through weathering, transformed into interstratified minerals, vermiculite and smectite. Major differences in the properties of the profiles developed on the two parent materials were not reflected by current soil classification.

Chemical and mineralogical properties of sandy and loamy‐sandy ochreous brown earths in relation to incipient podzolization in a brown earth—podzol evolutive sequence

SummaryChemical and mineralogical properties of ochreous brown earths have been studied with particular reference to: (1) the distribution within the profiles of Fe and Al compounds; (2) the occurrence of smectite‐like clay minerals in surface horizons.Ochreous brown earths studied belong to a developmental sequence of forest soils, from acid brown earths to ferric podzols, developed on sandy or loamy‐sandy acid parent materials. In such a soil sequence, both selective chemical and mineralogical data show clearly that podzolization is already active in ochreous brown earths, whereas such an incipient podzolization is quite undetectable by direct morphological observations.The distribution patterns of amorphous Fe and Al hydrous oxides and organic associations, clearly show the intergrade character of ochreous brown earths, when compared with the vertical distribution of Fe and Al forms in acid brown earths and podzolized soils. The Fe/Al ratio of both an NH4‐oxalate extract and an NaOH/Na‐tetraborate extract buffered at pH 9.7, measured in the A1B diagnostic horizon of ochreous brown earths, is a particularly appropriate and useful genetic criterion for the detection of incipient podzolization.Moreover, the presence of expansible clay minerals (degradation smectites) in the clay‐sized fraction of the surface horizons of ochreous brown earths (A1 and A1B) can be considered as supplementary evidence of incipient podzolization.

HILL LAND STUDIES IN THE GRAMPIAN REGION OF SCOTLAND

SummaryFactors affecting the growth of mixed grass swards in the Upper Don Basin were studied in two phases: in 1967–68 within the altitude range 260–440 m and in 1969–70 in the range 330–550 m O.D. In the first phase the interaction effects of altitude, aspect and soil parent material on herbage yields and mineral element contents were studied using 24 sites in a 3 × 2 × 2 factorial design, without fertilizer in 1967 and with nil, N. P and NP treatments in 1968. Total yields from 3 cuts at 2 monthly intervals averaged 4.84 tonnes D.M. ha−1 in 1968 with no overall significant altitudinal differences. Application of 75 kg N ha−1 as Nitrochalk raised the yield by over 40 per cent, slightly more in the presence of P on soils derived from mineralogically acidic parent materials. Overall, yields from soils on ‘basic’ materials were at least 25 per cent greater than from the ‘acidic’ ones. Sites with southern aspects mostly oulyielded the northern ones but not significantly so. In the second.phase 3 pairs of ‘acidic’ sites only were used, with an NPK treatment added to the 1968 treatments, and lime for the most acid soils at 550 m O.D. On these highest sites the yields were much reduced by the adverse climatic conditions.Samples of the dry matter from each treatment, replicate and cut at each site were analysed and the offtakes of N, P, K, Ca and Mg determined as well as the apparent recoveries of N, P, K and Ca from the fertilizers. The constraints of altitude on yield and composition were strongly correlated with the prevailing air and soil temperatures. The practical implications of the findings for upland livestock production are discussed but the detailed correlation and factor analyses of the data are presented in another paper.

REORGANIZATION OF SOIL MATERIALS IN THE GENESIS OF AN ACID LUVISOLIC SOIL OF THE PEACE RIVER REGION, ALBERTA

The Boundary soil is described as a "podzolic complex" developed from acidic parent material derived from shale of Cretaceous age. The soil has low pH and base saturation values that result from the formation of sulfates, primarily natrojarosite, and its subsequent alteration in the soil solum to various forms of hydrated iron oxides. The iron oxides impart to the B horizon reddish hues of high chroma. The acidic condition has resulted in weathering of clay-sized mica to vermiculite, especially in the upper part of the solum. Results from micromorphological and analytical studies also show that considerable clay and, to a much lesser extent, organically combined iron and aluminum have been leached from the upper solum and deposited throughout the lower solum and C horizon. Reorganization of clay through illuviation appears to extend well into the C horizon. Microscopic investigations show strong reorganization of materials in the upper solum to a granic–granoidic fabric by biological processes and in the middle solum to granoidic and metafragmic fabrics, probably through coalescence of granic units by freeze–thaw processes.

FE STATUS OF BRUNISOLIC AND RELATED SOIL PROFILES

Three pairs of soil profiles developed on calcareous parent materials and two pairs of soil profiles developed on acidic parent materials were chosen morphologically in the field to represent Brunisolic/Luvisolic and Brunisolic/Podzolic features, respectively. Oxalate-, pyrophosphate-, and dithionite-extractable Fe were determined for each horizon. Also, Fe was partitioned into crystalline, "aged" and "gel" amorphous hydrous oxides, and organic forms. Humic acids extracted from each horizon with alkali were characterized by infrared absorption spectroscopy. Soils developed on acidic parent materials contained more extractable Fe than did those developed on calcareous parent materials. Only one horizon fitted the requirements of the chemical definition of a Bf horizon. All three reagents indicated zones of depletion and accumulation of Fe in soils developed on calcareous parent materials; oxalate and pyrophosphate did but dithionite did not show these relationships for soils developed on acidic parent materials. With exceptions, extractable Fe was correlated with clay content on the soils with calcareous parent material but was correlated with organic carbon on the soils with acidic parent materials. Well-crystallized Fe showed horizon differentiation in soils with calcareous parent materials and is therefore a weathering product. In soils with acidic parent materials, crystallized Fe was the source of weathering product forms of Fe. Humic acids of soils with acidic parent materials were more highly oxidized and hence more capable of reacting with Fe than were those of soils with calcareous parent materials.