Genesis,Classification, and Management Requirements of Soils Formed in Windblown Material in the Guinea Savanna Area of Nigeria

Abstract

Eight pedons representing the major soils found within the Guinea Savanna region of northern Nigeria were studied with respect to their important morphological, physical, chemical, and other characteristics, and their suitability for sustainable agricultural production was evaluated. The most important soil characteristics observed for separating the soils into mapping units include presence or absence of petroferric contact, effective soil depth especially to hardpan layer, gravel and subsoil clay content. Dominant pedogenic processes, which influence the rate of soil development in the area, include plinthization, clay eluviation‐illuviation, iron (Fe)‐oxyhydroxide release (lateral movement and enrichment), eolian deposition, and leaching. According to the USDA system of classification, the soils (MU‐EDA) in the summit to upper slope are classified as Lithic Haplustepts, those (MU‐EDB) at the midslope are Typic Haplustepts, the MU‐EDC (lower slope soils) as Dystric Haplustepts, and the MU‐EDD (soils at the valley floors) as Oxyaquic Haplustepts. In the FAO/UNESCO system, a typical toposequence in the area consists of Dystric Cambisols (CMd) petroferric phase (MU–EDA and EDB), Dystric Cambisols (MU‐EDC), and Gleyic Cambisols (CMg) for the MU‐EDD mapping unit. The land capability and fertility capability classes of the soils were also established. The MU‐EDA, EDB, EDC, and EDD soil units were grouped into land capability class IVes, IIIes, IIs, and Vw and fertility capability class L”Rdk (6–8%), Ldehk (3–5%), Ldh, and Lgehk, respectively.     

Available phosphorus forms in forest soils and their possible ecological significance

Abstract

For a range of northern N.S.W. forest soils typical of Australian east coast forests, both inorganic and organic P have been determined on sequential soil extracts. Organic P was present in each extract, and in most extracts was a high proportion of the total P, regardless of soil type. Using the sum of the P concentrations in the most neutral extracts as an index of available P, the organic component ranged from 352 to 88% of the total available P. Soil parent material appeared to exert the strongest influence on both soil total P and on the proportion of organic P/total P which ranged from 26% to 81%. The results have been discussed in relation to soluble organic P and its availability in forest ecosystems. The soil organic P results have been discussed in relation to P availability and supply within the forest ecosystem.     

Seasonal and Daily Dynamics of the CO<Subscript>2</Subscript> Emission from Soils of <Emphasis Type="Italic">Pinus koraiensis</Emphasis> Forests in the South of the Sikhote-Alin Range

The presented study shows the results of measuring soil respiration in typical burozems (Dystric Cambisols) under mixed Korean pine–broadleaved forests in the southern part of the Primorskii (Far East) region of Russia growing under conditions of monsoon climate. The measurements were performed in 2014–2016 by the chamber method with the use of a portable infrared gas analyzer. Relative and total values of the CO₂ efflux from the soil surface on four model plots were determined. The intensity of summer emission varied from 2.25 to 10.97 μmol/(m² s), and the total CO₂ efflux from the soils of four plots varied from 18.84 to 25.56 mol/m². It is shown that a larger part of seasonal variability in the soil respiration is controlled by the soil temperature (R² = 0.5–0.7); the soil water content also has a significant influence on the CO₂ emission determining about 10% of its temporal variability. The daily dynamics of soil respiration under the old-age (200 yrs) forest have a significant relationship with the soil temperature (R² = 0.51). The pyrogenic transformation of Pinus koraiensis forests into low-value oak forests is accompanied by an increase in the СО₂ efflux from the soil.     

Estimation of soil weathering stage and acid neutralizing capacity in a toposequence Luvisol–Cambisol on loess under deciduous forest in Belgium

Soils derived from loess are extensive in Europe and are well suited for forestry. They are suspected to be poor acid buffers, however. We have estimated the weathering stage and acid neutralizing capacity of acid soils under forest in a toposequence on loess in the Belgian silt belt. The soils vary distinctly in morphology and physico‐chemical properties according to their topographic position. Dystric Cambisols have developed in colluvial deposits in the dry valley floors, whereas Dystric Luvisols have formed on the slopes in a rejuvenated material. The Cambisols are more acid and less saturated in bases than are Luvisols. They are strongly depleted of clay and contain less weatherable minerals. Easily weatherable minerals are concentrated mainly in the clay fraction of both soil types. Clay minerals of size < 2 μm therefore act as major sinks for protons in these soils. A simplified expression taking into account the total reserve in bases, total aluminium and iron occluded in silicates is used to estimate acid neutralizing capacity. Our estimates confirm that these acid loessic soils are indeed poor acid buffers. They show that the Dystric Cambisols depleted of clay are sensitive to potential acidification, whether natural or man‐made.     

Conditions related to solubility of rare and minor elements in forest soils

Soil solutions expelled by high‐speed centrifugation (13900 g) of intact soil sample cores at field moisture from 30 forest topsoils (A horizons of mainly Dystric and Eutric Cambisols, according to the FAO‐Unesco system) low in clay were subjected to analysis of 60 elements, using ICP‐MS and ICP‐AES. Concentrations measured were related to soil and soil solution properties assumed to be important for the solubility of elements, using stepwise regression analysis. On an average two thirds of the variability in soil solution concentration of elements were accounted for by, in particular, organic C concentrations, pH and/or nitrate concentrations of the solutions, varying among elements from 19 to 90 %. Concentrations of elements strongly positively related to soil solution acidity were Al, Be, Ge, Li, Ni, Pb, and Zn, strongly negatively related to acidity were Ca, Mo, and W. Most positively related to nitrate concentrations in soil solutions were B, Ba, Cd, Mg, Mn, and Sr; negatively were Nb, Ta, and Ti. Concentrations of organic C in the soil solutions correlated positively, often quite closely, with most of the other elements studied, including La, all the lanthanides, and with Ag, Br, Cr, Fe, Ga, Hf, Hg, In, P, Th, U, Y, and Zr. Soluble organic compounds were apparently ’︁carriers’ of these elements in the soil solution. The concentrations of elements in HNO₃ digests of the soils usually accounted for just little or no statistical variability of their soil solution concentrations.     

The influence of parent material on soil fertility degradation in the coastal plain of Tanzania

Differences in the vulnerability of soils to fertility degradation are compared for two major soil groups located in the coastal plain of Tanzania and cropped with sisal (Agave sisalana). Ferralsols derived from intermediate gneiss of Precambrian age and Cambisols developed in Jurassic and Neogene limestones partly covered with Quaternary deposits were selected for comparison. A clear influence of parent material was apparent when soils were continuously cropped with sisal and no fertilizers were applied. Serious soil fertility decline occurs in Ferralsols, but Cambisols are resilient to chemical degradation and the fertility decline in these soils was very limited. The differences in degradation rates are explained by the lower initial fertility and low nutrient reserve of Ferralsols, while the Cambisols had higher initial fertility levels and nutrients removed by the sisal crop are replenished by the weathering of the underlying parent material. Sustainable soil fertility management of Cambisols includes only NPK fertilization, but heavy dressings of lime, organic manures and/or chemical fertilizers are required to improve the fertility status of the Ferralsols and to produce crops in a sustainable manner.     

Schwefelformen in Waldböden SO2-belasteter Standorte des Fichtelgebirges

Sulfur fractions in forest soils of the SO₂-polluted Fichtelgebirge The sulfur status of a soil sequence (two Dystric Cambisols, Haplic Podzol, Eutric Cambisol) in SO₂-polluted coniferous and hardwood forests of the Fichtelgebirge (North-East Bavaria) is investigated. In the mineral soil layers S_t fluctuates between 37 to 943 ppm; 11–84% of S_t is S_p. Layers rich in clay contain up to 79%-S_E, whereas in sandy to silty substrates organic bound C?S-S dominates. The organic surface layers show 1.0–2.9‰ S_t, maximum in the Oh. 69–90% of S_t are C?S-S. S_p is low with a maximum in the L-horizons (9–19% of S_t). S_E is vice versa, because values increase from L (0–8% of S_t) to Oh (7–22% of S_t). The characterization of the sulfur status in a forest ecosystem by investigation of organic layers presumably is more reliable than the results of needle and mineral soil analyses.     

Soil REE patterns as tracers of the emplacement of metal-rich anthropogenic materials. A case study in Moa (Cuba)

Purpose

Are rare earth element (REE) patterns employable as tracers in human interventions of bulk soil disturbances, when high concentrations of metals are involved in the in situ soil disturbance? In terms of bulk soil disturbance, it is difficult to distinguish between bulk soil disturbances and emplacement of new earthen material. Chemical fingerprinting, in particular REE plus yttrium, is applied across many fields, but predominantlyin tracking the sources of potential environmental contaminants.

Materials and methods

The REE normalised patterns (HNO₃:HF:HCl 3:1:1 digestion, ICP-MS) of two Calcaric Cambisols were compared with those of a Geric Ferralsol (Novic, Technic) originated from selective overburden of nickel mining (20°40′ N, 75°35′ W).

Results and discussion

The sum of REE, including Y and Sc, ranged between 48 and 101 mg kg^?1. Principal component analysis (PCA) shows a discriminant role of REE. REE signature normalised to the upper continental crust shows slight positive Eu and negative Ce anomalies in the case of both Calcaric Cambisols, while the Geric Ferralsol shows anomalous patterns with the same anomalies plus a slight positive anomaly of Y, as a consequence of the addition of mining by-products.

Conclusions

Here, we show that REE patterns of the individual horizons of a soil have characteristics that allow us to distinguish undisturbed from soils mixed with other soil materials, including those with different pH values and high metal contents (e.g. Cr, Mn, and Ni ≥?0.5%, Fe ??5 wt%). Our results demonstrate, by using soils with contrasting characteristics, that their origins can be traced via the patterns of their REEs, even in the presence of high concentrations of other metals. In perspective, when background maps of all REE elements in soils are available worldwide on an appropriate scale, this enables us to obtain a level of discriminatory detail on a local scale.

     

Cation exchange resin and test vermiculite to study soil processes in situ in a toposequence of Luvisol and Cambisol on loess

Both the ion accumulation on cation exchange resin and the transformation of test vermiculite in situ have been used to identify current processes in acid forest soils. We used such test materials to study weathering in a toposequence Dystric Luvisol–Spodo‐Dystric Cambisol on loess under deciduous forest in Belgium. The resin and a trioctahedral vermiculite were inserted for 2 years in the major horizons, down to a depth of 60 cm. The cation accumulation on the resin revealed that four main acid‐consuming systems are currently active in the toposequence. With decreasing acid neutralizing capacity, these systems are in the Luvisols: (i) the pool of exchangeable bases, (ii) the Al‐bearing minerals controlling the Al concentration in the liquid phase; and in the podzolized Cambisols: (iii) the less weatherable K‐bearing minerals, (iv) the Mg‐bearing phyllosilicates made free of Al interlayers in complexing conditions. The loss of cation exchange capacity in the test vermiculite is related to Al interlayering. However, this process masks a significant interlayer accumulation of magnesium, which is generated by the weathering of the test mineral itself. The largest interlayer accumulation of Mg occurs in the podzolized Cambisol, suggesting more intense weathering of the test vermiculite in this soil.     

Chemical Properties and Macronutrients of Oak Soils in Northwest Spain

Abstract

This study characterizes the soil types on which natural stands of Quercus robur L. grow in northwest Spain. Nineteen edaphic parameters were obtained from the data collected in the sampling of 39 oak soils. Siliceous substrates were present in all of the stands, with granite and schist substrates being dominant. The soils on which the stands were grown were mainly Dystric cambisols. The values of the parameters that reflect the main chemical and biological soil properties [pH, organic matter, nitrogen (N), and carbon (C)/N ratio] were similar to the values considered optimal for these formations by other researchers. The exception was the values obtained for organic matter, which were slightly higher. The concentrations of nutrients in these soils were considered relatively low or medium as compared with the concentration of nutrients in soils under pine and eucalyptus forests in the study area, except phosphorus, which was considerably higher.     

Available soil nutrients and water content affect leaf nutrient concentrations and stoichiometry at different ages of Leucaena leucocephala forests in dry-hot valley

Purpose

The carbon (C), nitrogen (N), and phosphorus (P) concentrations of leaves can reflect soil nutrient supply conditions and changes in soil. An understanding of species adaptability and nutrient use efficiency in extreme ecosystems can help land managers choose effective methods to improve management and community structure of introduced plants which may induce biological invasion and limit the regeneration of native species.

Materials and methods

We selected the Leucaena leucocephala forests in three ages (9, 15, and 26 years old) in the Jiangjiagou Gully to study the relationships between (i) soil factors and forest age and (ii) leaf nutrient concentrations. Soil factors and leaf nutrients were measured in nine sampling quadrats of 10?×?10 m of each plot. We used ANOVA to examine differences in leaf variables and soil factors at different ages of L. leucocephala forest. Pearson’s correlation analysis and linear regression analysis were conducted to identify the relationships between soil factors and leaf variables. Then, we used analysis of covariance to examine combined effects of forest ages and soil factors on leaf variables.

Results and discussion

Leaf N was significantly correlated with available P, while leaf P was significantly correlated with both available P and available N. Leaf N and P had no significant relationship with soil total N and P. Leaf C:N:P stoichiometries had a higher significant correlation with total N, available N, and soil water content.

Conclusions

Our findings illustrate that available N and available P are the main limitations for L. leucocephala, though available P imposed a stronger limitation than available N. Moreover, soil water content played an indispensable role on nutrient accumulation and the soil ecological environment. Our results provide useful information to improve L. leucocephala community structure and reduce soil degradation in a dry-hot valley.

     

Characteristics of phosphorus fractions in the soils derived from sedimentary and serpentinite rocks in lowland tropical rain forests,Borneo

ABSTRACT

Soil organic phosphorus (P) is an important P source for biota especially in P-limited forests. Organic P has various chemical formations which differ in bioavailability and these organic P can be degraded by phosphatase enzymes. Here, we report soil P fractions inferred from solution ³¹P-NMR spectroscopy and soil phosphatase activities of two tropical rain forests on contrasting parent materials; sedimentary and ultramafic igneous (serpentinite) rocks. Compared to the sedimentary soils　and previous studies, P fractions of the serpentinite soils have distinctly high proportions of pyrophosphate and scyllo-inositol hexakisphosphate (scyllo-IP₆). The accumulation of pyrophosphate and scyllo-IP₆ may be related to strong sorptive capacity of iron oxides present in the serpentinite soils, which implies a consequent low P availability in the serpentinite soils. Mean value of soil phosphatase activities was higher in the serpentinite soils than in the sedimentary soils, suggesting that biota in these serpentinite forests depend more on soil organic P as a P source.     

In situ weathering of rocks or aeolian silt deposition: key parameters for verifying parent material and pedogenesis in the Opawskie Mountains—a case study from SW Poland

Purpose

The aims: (1) to investigate the role of the in situ weathering of bedrock in providing substrate for soil formation; (2) to evaluate the aeolian contribution to the mountainous soils in the vicinity of thick loess cover; and (3) to determine the influence of aeolian silt on further soil development.

Materials and methods

The sampled sites were arranged along the slope toposequence, where an aeolian/silt admixture possibly occurred. Each soil catena started at the top of a hill and ended at its foot. Such an arrangement of the soil profiles ensured the tracking of loess thickness variations and detection of the depth of the residuum-derived materials. One reference soil profile, consisting of aeolian silt deposits, was made. The following soil properties were determined: pH, organic carbon content, soil texture, exchangeable acidity, exchangeable ions and geochemistry. In addition, thin sections were prepared from rock samples to confirm the type of bedrock present.

Results and discussion

The soils in the studied area were classified as Cambisols, Luvisols and Stagnosols, characterised by silt loam texture and a high content of elements indicating an aeolian silt contribution—Hf (7.4 to 14.8 ppm) and Zr (274.4 to 549.0 ppm). These values differ strongly from the residues typical of weathered quartzite, greywacke or catalasite substrates, which generally have low concentrations of Hf and Zr (0.7 to 7.0 ppm and 26.0 to 263 ppm, respectively). Based on the morphological, textural and geochemical data of the studied soils, three layers were distinguished, which show different inputs of aeolian silt: (1) an aeolian silt mantle; (2) a mixed zone in which loess was incorporated into the local material; and (3) a basal zone, free of the influence of aeolian silt. Based on the obtained results, a hypothetical pathway for soil formation in mountainous areas, influenced by aeolian silt admixing, was proposed.

Conclusions

Our study demonstrates that the soils developed in the Opawskie Mountains are characterised by an aeolian silt influence. This differentiates them from weakly developed soils, which comprise materials formed during in situ weathering only. Materials originating from bedrock weathering did not play an independent role as the parent material for the studied pedons. Aeolian silt was admixed with already existing autochthonous substrates, or completely replaced them. This influence on the soil formation resulted in the occurrence of Luvisols, Stagnosols and Cambisols. Such soils cannot be formed from the weathering of quartzites and greywackes, which contribute to a less structure-forming medium.

     

Clear increases in acetylene reduction by soil bacteria from an East Siberian Taiga forest bed under conditions mimicking the natural soil environment

Abstract

In boreal forest ecosystems, nitrogen imbalance has long been discussed as a mystery with regard to its high biomass production. Under conditions widely used for the soybean nodulation bacterium Bradyrhizobium japonicum, microbiota in forest bed soil often do not show any significant acetylene reduction. However, in a recent study, soil bacterial microbiota in an East Siberian Taiga forest bed and bacteria isolated from the soil show remarkable acetylene reduction in nitrogen-poor soft-gel medium solidified with gellan gum instead of agar. Thus, we precisely investigated optimal culture conditions including compositions of the medium; appropriate conditions for the soil microbiota were determined as follows: 0.5 g L^?1 D-mannitol as the carbon source, 10–15°C incubation temperature and medium pH 6.2. These culture conditions resembled the physicochemical conditions of the active layer in the East Siberian boreal forest bed on the permafrost. In fact, mannitol, which was the most appropriate carbon source, was obtained as a major sugar component of the cowberry root mats that cover the larch forest bed in this region. The most profitable concentration of D-mannitol (0.5 g L^?1) for acetylene reduction was only 1/20 or 1/30 of the amount of the carbon source used in worldwide acetylene reduction assays. In a similar manner, 10–15°C, which was the most profitable incubation temperature range, was close to the reported temperature of the active layer of the bulk soil in summer. us, even in a 3.0 g L^?1 gellan gum medium, an acetylene reduction assay under the imitated soil conditions led to clear increases in acetylene reduction of the bacterial communities tested. The N₂-fixing potential of boreal forest bed soil had thus ever been evaluated unfairly low, because the world wide assay conditions were too far from the soil environments.     

Soil phosphorus of stable fraction differentially associate with carbon in the tropical forest and savanna of eastern Cameroon

ABSTRACT

The forest–savanna transition zone, which contains nutrient-poor soils (Oxisols), is found throughout central Africa. To evaluate the effect of deforestation on soil phosphorus dynamics, which regulate the plant growth in this area, we quantified the relationship between phosphorus (P) and carbon (C) in different fractions and compared their relationship to forest and savanna (deforested vegetation) in eastern Cameroon. We analyzed the P, C, and nitrogen (N) contents of soil using the physical fractionation method (0.25–2.0 mm as macro-particulate organic matter [M-POM]; 0.053–0.25 mm as micro-POM; and <0.053 mm as Clay+silt) in different land management (young and old forests and annual and perennial grass savannas at 100-cm soil depth). We found larger soil P stock in forests (4.7–4.9 Mg P ha^?1) than that in savannas (3.4–4.0 Mg P ha^?1), though soil C and N stocks were similar between the vegetation. We also observed lower soil P stock in the active fraction (M-POM) with its higher C:P and lower C:N ratio in forest surface layer (0–10 cm), indicating that forests have lower available soil P. By using the regression analysis, we found a clear relationship between P and C in the stable fraction (Clay+silt) of the upper layer (0–40 cm) for each land management, and the coefficient of the regression was clearly different between the forest and savanna. It indicates that a more chemically complex organic P form of the stable fraction exists in forest soil than in savanna soil. These results indicate that the deforestation (savannazation) affect the active and stable P dynamics and it should cause the lower soil P stock of the upper layer in savanna than in forest.     

Effects of biochar application in forest ecosystems on soil properties and greenhouse gas emissions: a review

Purpose

Forests play a critical role in terrestrial ecosystem carbon cycling and the mitigation of global climate change. Intensive forest management and global climate change have had negative impacts on the quality of forest soils via soil acidification, reduction of soil organic carbon content, deterioration of soil biological properties, and reduction of soil biodiversity. The role of biochar in improving soil properties and the mitigation of greenhouse gas (GHG) emissions has been extensively documented in agricultural soils, while the effect of biochar application on forest soils remains poorly understood. Here, we review and summarize the available literature on the effects of biochar on soil properties and GHG emissions in forest soils.

Materials and methods

This review focuses on (1) the effect of biochar application on soil physical, chemical, and microbial properties in forest ecosystems; (2) the effect of biochar application on soil GHG emissions in forest ecosystems; and (3) knowledge gaps concerning the effect of biochar application on biogeochemical and ecological processes in forest soils.

Results and discussion

Biochar application to forests generally increases soil porosity, soil moisture retention, and aggregate stability while reducing soil bulk density. In addition, it typically enhances soil chemical properties including pH, organic carbon stock, cation exchange capacity, and the concentration of available phosphorous and potassium. Further, biochar application alters microbial community structure in forest soils, while the increase of soil microbial biomass is only a short-term effect of biochar application. Biochar effects on GHG emissions have been shown to be variable as reflected in significantly decreasing soil N₂O emissions, increasing soil CH₄ uptake, and complex (negative, positive, or negligible) changes of soil CO₂ emissions. Moreover, all of the aforementioned effects are biochar-, soil-, and plant-specific.

Conclusions

The application of biochars to forest soils generally results in the improvement of soil physical, chemical, and microbial properties while also mitigating soil GHG emissions. Therefore, we propose that the application of biochar in forest soils has considerable advantages, and this is especially true for plantation soils with low fertility.

     

The nature and origins of diester phosphates in soils: a 31P-NMR study

Soils of two climosequences in Russia were investigated by ³¹P-NMR spectroscopy. They comprised Dystric Podzoluvisols, Haplic Greyzems, Calcic Chernozems, and Gypsic Kastanozems, which are located along temperature and precipitation gradients of the Russian Plain. Another sequence of soils included forest Humic Cambisols and Umbric Leptosols of subalpine and alpine meadows, which are formed in different climatic conditions along a climosequence of the Mt. Malaya Khatipara (northern Caucasus). The results showed that accumulation of DNA was high in the cold, wet, and acid soils (Dystric Podzoluvisol, alpine Umbric Leptosol), while phospholipids and teichoic acids mainly accumulated in the more microbially active soils. We performed a laboratory incubation experiment to test the relationship between microbial biomass P and P species identified in soil extracts. The proportions of P compounds resonating at 0.5-3.0 ppm in the NaHCO₃ and H₂SO₄ extracts from the incubated Humic Cambisol increased. The amounts of phosphate diesters resonating at 0 ppm in the same extracts and in the subsequent NaOH extracts decreased after incubation. Based on the results of ³¹P-NMR spectroscopy of native soils and of the laboratory incubation experiment we concluded that signals at 0 ppm in spectra of soil alkaline extracts belong to DNA P which is mainly stabilised in soil organic matter outside microbial cells (at least in soils with relatively low microbial activity). Phospholipids-teichoic acids P extracted with 0.5 M NaHCO₃ seems to be derived from soil microbial biomass, and its proportion can reflect the microbial activity in the soil.     

Neubauer seedling technique to determine availability of nutrient elements for wheat from selected South African soils

Abstract

The quantity of plant nutrient elements removed from soil by wheat (Triticum aestivum) seedlings were compared with the results of soil tests. Four soils were selected to represent the major parent material and climatic factors responsible for the formation of important agricultural soils in the central eastern Cape Province of South Africa. Acid‐washed sand was used as control. Seedlings were grown for 21 days and nutrient element content in both plant material and soil were determined. Soils derived from dolerite rocks had significantly (P<0.05) higher calcium (Ca), magnesium (Mg), potassium (K), sodium (Na), and phosphorus (P) than those derived from sedimentary rocks. However, iron (Fe), manganese (Mn), and copper (Cu) were higher in soils derived from sedimentary rocks compared to those from dolerite rocks. The differences are attributed to elemental composition of minerals in the two parent rock materials. Within each rock group, soils derived from sites with higher temperature and low rainfall (semi‐arid climate) had significantly (p<0.05) higher nutrient element content than those from sites with lower temperatures and higher rainfall (humid climate). As far as plant growth is concerned, all the soils were well supplied with Ca, Mg, K, Na, and zinc (Zn), but were deficient in P, Fe, and Mn. The trend in uptake of soil nutrient elements by wheat seedlings mirrored their concentration in the soils. Estimates of plant‐available nutrient elements as determined by soil tests and their uptake as determined by tissue concentration were highly correlated for some nutrient elements (r²=0.83, 0.79, 0.94, 0.54, 0.69, and 0.61 for Ca, Mg, K, P, Na, and Zn, respectively) and weak for others (r²=0.47, 0.35, and 0.37 for Fe, Mn, and Cu, respectively). Notwithstanding the shortcomings of extrapolating pot derived results to field conditions, it is concluded that the Neubauer technique may offer a rapid and relatively inexpensive way of relating extractable nutrient elements with plant uptake and growth. Further in country correlation studies are, however, recommended.     

Response of wheat to sulfur fertilization

Abstract

Coker 747³ wheat (Triticum aestivum L.) was grown on Keo silt loam (coarse‐silty, mixed, thermic Dystric Fluventic Entrochrepts) with four S sources applied at various rates for two years. The innate S level of this soil was not adequate for optimum grain yield; therefore, additional S significantly increased grain yield and S concentration and decreased N/S ratios in wheat tissue. Minimum S concentration and N/S ratios in plant tissue for maximum yield ranged from 1.3 to 2.73 g S/kg and 9.5 to 19.2, respectively.     

Genesis of a So-called Ferrolysed Soil of Bangladesh

It 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.