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Land-use change, particularly soil organic carbon (SOC) loss induced by shifting cultivation (jhum) is a common land degradation issue in the hilly tracts of the humid tropics. The SOC concentration comprises different pools (labile and recalcitrant fractions), and each fraction responds to temporal dynamics of adopted management practices at varying magnitudes, such as deforestation followed by cultivation. However, information on the variation of different SOC pools due to cultural practices of vegetation burning and postburn agricultural practices (crop production) associated with shifting cultivation remains inadequate. In the present investigation, we examined the effect of burning and postburning cultivation on SOC pools across different forest fallow periods at Kolasib district, Mizoram state of the north-eastern Himalayan Region of India. Results revealed increase in the soil C stocks and total organic carbon (TOC) due to the increase in the length of fallow periods ranging from 3 to 23 years. The TOC decreased significantly compared with antecedent concentrations before vegetation burning. This was mostly attributed to the reduction in contribution of active pools (very labile and labile) to TOC from 69% to 60%. However, contribution of passive pools (less labile and nonlabile) to TOC concentration increased from 31% to 40%. Postburn cultivation also resulted in reduction of TOC as well as considerable variation in the proportion of different SOC pools to TOC concentration. Among the different pools of SOC, the very labile C pool was most sensitive to land-use change induced by shifting cultivation (phytomass burning and postburn cultivation). The labile SOC pools can act as a sensitive indicator for devising suitable location specific management practices for restoration of soil health through SOC dynamics in degraded jhum lands in hilly ecosystems. Additional keywords: carbon cycling, ecosystem, land degradation, soil quality., Introduction Climate change and its adverse impact on natural resources including soil is one of the major issues being discussed widely across many parts of the world. It is believed [...]

Land-use change has been shown to affect soil quality and may lead to soil degradation. The effects of land-use change from natural forest to tea farming on soil properties and quality were studied within Guilan Province of northern Iran. Thirty-six soil samples (0-30 cm) were randomly collected from six sites with three replications at each site. The soil quality of forest and tea farms was determined using the cumulative rating (CR) index and the Cornell Comprehensive Assessment of Soil Health (CASH) scoring function. Effects of land-use change on soil quality or health were significant (P Additional keywords: deforestation, land degradation, soil quality, tea farming., Introduction Land use resulting in land cover change directly influences the terrestrial ecosystem and biogeochemical processes and may lead to soil degradation (Betts el al. 2015). Land degradation has been [...]

In a broad-scale survey across pasture-based grazing systems in south-eastern Victoria, soil biological and chemical properties were measured in an effort to establish baseline levels for commonly used indicators of soil health. Although soil properties were highly variable among sites and biological properties were difficult to predict, total soil C was found to be closely associated with soil cation exchange capacity (CEC). Importantly, the strength and nature of relationships between soil properties differed among soil textural classes. We also measured a range of soil and vegetation properties in a small number of patches of remnant vegetation and their adjacent grazed pastures. This was done in an effort to assess the sensitivity of these measures when used on samples collected from strongly contrasting land-use types. Although some factors, such as mycorrhizal colonisation of roots and soil C, did differ between the two land-use types, other factors measured in this study did not. Together, the findings of this survey provide baseline information on the landscape scale for commonly used indicators of soil health. The study explores relationships between these soil properties and assesses how they differ between two strongly contrasting land-use types. The results are discussed in the context of monitoring soil and vegetation attributes relevant to soil health. Additional keywords: carbon, microbial biomass, mycorrhizas, nutrient cycling, soil survey., Introduction In recent years there has been an increase in global consumption of animal-derived food products and this trend is expected to continue given current projections of global human population [...]

This study aimed to investigate the effects of different biochars on soil enzyme activities associated with soil carbon (C) mineralisation. Biochars were produced from two types of feedstock (fresh dairy manure and pine tree woodchip) at temperatures of 300°C, 500°C, and 700°C. Each biochar was mixed at a ratio of 5% (w/w) with a forest loamy soil and the mixture was incubated at 25°C for 180 days. Soil mineralisation rates, soil dissolved organic C, soil microbial biomass C, and five soil enzyme activities were measured during different incubation periods. Results showed that biochar addition increased soil enzyme activities at the early stage (mainly within the first 80 days) because biochar brought available nutrients to the soil and increased soil dissolved organic C and microbial activity. Soil enzyme activities were enhanced more by the dairy manure biochars than by the woodchip biochars (P< 0.05). The enhancement effect on enzyme activities (except catalase activity) was greater in the treatments with biochars produced at lower pyrolysis temperature (300°C). Linear relationships between some soil enzymes and C-mincralisation rates might indicate that the increased enzyme activities stimulated soil C mineralisation at the early stage. However, the biochar additions could result in great C sequestration in the long term, especially for the woodchip biochars pyrolysed at higher temperatures. Additional keywords: biochar, soil carbon mineralisation, soil carbon sequestration, soil enzyme activity., Introduction Enzymes are involved in many biochemical processes in soils, such as the organic matter decomposition, carbon (C) mineralisation, and nutrient cycling (Patra et al. 2006; Makoi and Ndakidemi 2008). [...]

Soils in boundary conditions of contrasting ecosystems generally show unique features. Transition often leads to changes in soil-forming processes, whereby the environment never comes to equilibrium and therefore the soil chemistry and mineralogy show different influences. Such an environment was analysed in the Saloum River basin, west-central Senegal. The objective was to identify the main pedogenic processes prevailing in this saline and acid pedoenvironment and to assess the influence of environmental factors (climate, topography, soil salinity and acidity) on local soil formation and mineral distribution. The terrace landscape is built up by a floodplain, a low terrace, which is still influenced by groundwater, and a middle terrace. The results show that soil properties are strongly influenced by hydrology, salinity and acidity in the entire toposequence: Glcyic Hyposalic and Hypersalic Solonchaks (Sulfatic) in the floodplain, Haplic Gleysols (Thionic) in the low terrace, and Endogleyic Arenosols in the middle terrace. The oxidation of pyrite followed by the redistribution of the main products ([Fe.sup.2+] and S[O.sub.4.sup.2-]) represents the major chemical process responsible for iron oxide and jarosite formation. Mineral distribution and crystallinity are linked to the landscape position, which controls the hydrological behaviour and reactions of Fe and S ions. Finally, we observed intrapedon processes such as gleysation, sulfidisation and sulfurisation, as well as interpedon processes such as salinisation, colluvio-alluviation and lateral eluviation. The combination of processes depends strongly on the landscape positions. Additional keywords: acidity, acid sulfate soil, iron oxide, jarosite, salinity, Senegal., Introduction Coastal landscapes around the world frequently contain acid sulfate soils (ASS). These are defined as soils that are severely acidic or have the potential to become acidic as a [...]

To investigate the fate of nitrogen (N) from urine, dairy cow urine was amended with bromide (Br) and chloride (Cl), and applied onto a loamy sand soil with an underlying vadose zone of gritty coarse sands and pumice fragments with groundwater at ~5.5 m depth. Textural changes and hydrophobicity resulted in heterogeneous flow and high variability in the Cl, Br and N masses captured. Three forms of N derived from the urine, organic-N (org-N), ammonium-N (N[H.sub.4]-N) and nitratc-N (N[O.sub.3]-N), were measured at 0.4 m depth. At 1.0 m depth, effectively all measured N was N[O.sub.3]-N. At 4.2 m, the mass of recovered N (average 33% of applied N, s.d. 21 %), although solely speciated as N[O.sub.3]-N, was not significantly different from that at 0.4 m (average 24.5% of applied N, s.d. 0.1%), suggesting that no substantial assimilation of N[O.sub.3]-N had occurred in this vadose zone. Below the interface of the Taupo Ignimbritc and the Palaeosol at 4.2 m depth, recoveries of the Cl and Br tracers were negligible. In addition, the isotopic signatures ([δ.sup.18]O and [δ.sup.15]N) of the nitrate were different and the N[O.sub.3]-N concentrations were higher than in the upper vadose zone. These results all suggest that the Palaeosol was acting as a hydraulically limiting layer resulting in lateral unsaturated flow occurring at this interface. The fact that no nitrate assimilation was observed in this field study, despite previous laboratory studies showing substantial assimilative capacity, underlines that that the nitrate assimilative capacity in the vadose zone is a function of both hydrological and biogcochemical factors. Additional keywords: AETL, chloride tracer, hydraulic barrier, lateral movement., Introduction The process of determining the maximum land-use intensity commensurate with maintaining freshwater quality targets suffers from paucity of reliable data on the fate of nutrients along the vadose zone-groundwater [...]

Physical quality of the soil seedbed affects germination, seedling emergence and crop establishment. The aim of this work was to determine the least-limiting water range (LLWR) of a soil seedbed cultivated for 18 consecutive years under no-till (NT) and submitted to mechanical chiselling (NT-M) and biological chiselling by a forage radish cover crop (NT-B). The study was carried out in Ponta Grossa, Parana, Brazil. The experimental design was randomised complete blocks with four replications. Soil samples at 0-5 and 5-10 cm depths were collected at 6 and 18 months after the start of the experiment which corresponded to maize (October 2009) and soybean (November 2010) planting. Water-retention curve, penetration-resistance curve, soil and relative bulk density, and LLWR were determined. Bulk density did not differ among treatments at 0-5 cm depth for both evaluation periods. At 5-10 cm soil depth, the NT-M treatment showed the lowest bulk density at the first sampling (2009), whereas NT-B showed the highest bulk density at the second sampling (2010). Soil penetration resistance was the most limiting factor of the LLWR, which was greater in NT-M for both soil layers at the first sampling. At the second sampling, the NT treatment had the greatest LLWR at 0-5 cm, but at 5-10 cm soil depth, both NT and NT-M had higher LLWR than NT-B. The efficiency of mechanical chiselling in improving soil seedbed physical quality lasted 18 months after its application. Biological chiselling was efficient in improving soil air-filled porosity in both periods as evaluated by the LLWR. Additional keywords: bulk density, Raphanus sativus L., soil compaction, soil penetration resistance, soil water retention., Introduction No-till is one of the most important soil-management systems for grain production in modern agriculture. It has been applied to ~117 Mha around the world, of which ~26 Mha [...]

The importance of soil organic carbon (SOC) in maintaining soil health is well understood. However, there is growing interest in studying SOC with an emphasis on quantifying its changes in space and time. This is because of the potential for soil to be used to sequester atmospheric C. There are many issues which make this difficult, for example shortcomings in sampling designs, and differences in vertical and lateral sampling supports between surveys, particularly if legacy data are used as the baseline survey. In this study, we systematically work through these issues and show how a protocol can be developed using design-based and model-based statistical approaches to estimate changes in SOC in space and time at different spatial supports. We demonstrate this protocol in a small subcatchment in the upper Namoi valley for estimating the change in SOC over time, whereby the baseline dataset was collected during 1999-2001 and is compared with a dataset from November 2010. The results from both design-based and model-based approaches revealed a drop in SOC across the catchment between the two survey periods. A 0.26% drop in SOC was reported globally across the catchment. Nevertheless, the change in SOC reported for both approaches was not statistically significant. Additional keywords: monitoring, sampling, soil carbon, space-time, design-based, model-based., Introduction Carbon exists in soil as soil organic carbon (SOC) and as soil inorganic C. Of these two forms, SOC plays an important role in a range of biological, chemical [...]

Ectomycorrhizal (ECM) fungal community composition is structured by soil properties, but specialization for woody microsites by ECM fungi is equivocal. Because fungal mycelia explore the substrate and colonize nutrient patches, studies targeting ECM fungal hyphae may reveal niche preferences. Moreover, studying the distribution and composition of ECM fungal hyphal communities contributes to our understanding of nutrient cycling in forest soils. We used next-generation sequencing to determine whether the composition of forest floor fungal communities present as hyphae differed among three microsite types: decayed wood, mineral soil adjacent to intact logs, or control mineral soil of mature spruce forests in British Columbia. The microsites were located in three blocks that were separated by 1 km and varied in elevation. Across the site, the ECM fungal lineage /amphinema-tylospora was the most operational taxonomic unit (OTU)-rich group, while the saprotrophic order Mortierellales was also dominant. ECM fungal species differed among microsites. For example, ECM fungal OTUs identified as Tylosporafibrillosa and Russula curtipes were more frequent in decayed wood as compared with control mineral soil. However, ECM fungal communities were more strongly structured by block characteristics, and we conclude there is no distinct group of ECM fungi specializing in the soil microsites examined in this forest. Key words: next-generation sequencing, forest soil, fungal hyphae, Picea engelmannii, ectomycorrhizal ecology. La composition d'une communaute fongique ectomycorhizienne (ECM) est structuree par les proprietes du sol, mais la specialisation des ECM envers des microsites ligneux est equivoque. Parce que les myceliums fongiques explorent le substrat et colonisent les parcelles comportant des nutriments, des etudes ciblant les hyphes fongiques ECM peuvent reveler leurs preferences sur le plan des niches. De plus, l'etude de la distribution et de la composition des communautes hyphales fongiques d'ECM contribue a notre comprehension du cycle des nutriments dans les sols forestiers. Nous avons utilise le sequencage de derniere generation afin de determiner si la composition des communautes fongiques du sol forestier presentes sous forme d'hyphe differait en fonction de trois types de microsites: le bois en decomposition, le sol mineral adjacent aux billes intactes ou le sol mineral controle de forets matures d'epinettes en Colombie-Britannique. Les microsites etaient localises dans trois blocs separes d'un km et variaient sur le plan de l'elevation. A travers le site, le lignage fongique /amphinema-tylospora d'ECM etait le groupe le plus riche en unites taxonomiques operationnelles (UTO), alors que l'ordre saprotrophe des Mortierellales etait aussi dominant. Les especes d'ECM fongiques differaient en fonction du microsite. Par exemple les UTO fongiques d'ECM identifiees comme Tylospora fibrillosa et Russula curtipes etaient les plus frequentes sur le bois en decomposition comparativement au sol mineral controle. Toutefois, les communautes fongiques d'ECM etaient plus fortement structurees par les caracteristiques du bloc, et nous concluons qu'il n'existe pas de groupe fongique distinct de d'ECM se specialisant dans le sol des microsites examines dans cette foret. [Traduit par la Redaction] Mots-cles: sequencage de derniere generation, sol forestier, hyphes fongiques, Picea engelmannii, ecologie des ectomycorhizes., Introduction The extensive mycelia of soil fungi play an important role in forest decomposition and nutrient cycling by releasing numerous degradative enzymes and subsequently absorbing soluble molecules (Carlile et al. [...]

Most soils in eastern Australian contain abundant soil potassium (K) reserves, and it is often assumed that there are no problems with soil K status. However, soil K deficiency has been reported in selected locations, and for viticulture, there are potential problems with high soil 1C concentrations due to the application of winery wastewater. This study investigated different soil K variables and plant variables for six soils with distinctive properties from across central and southern New South Wales to determine the presence of soil K deficiency and to understand the effect of adding K on the dynamics of soil K availability. A glasshouse experiment compared the selected soils under three fertiliser K rates with forage kale as the test species. Highly significant differences (P< 0.001) were found for soil and fertiliser K rate effects for three measures of soil K (solution IC, soln K; exchangeable K, exch. K; tetraphenyl borate K; TBK). Significant soil and fertiliser rate effects were detected (P Additional keywords: forage kale, illite, nutrient efficiency indices, plant K uptake, sodium tetraphenyl boron extractable potassium. Received 3 June 2013, accepted 17 October 2013, published online 6 March 2014, Introduction Many Australian soils contain major potassium (K) reserves, and so K is not often considered a nutrient of concern (Williams and Raupach 1983). Despite the perceived abundance of soil [...]

Abstract: Accessible information on Galapagos soils is very limited. Much of the existing, although still scarce, information is several decades old and not easily retrieved. The aim of this paper [...]

This paper presents findings of comparative evaluation of selected soil physical quality (SPQ) indicators, obtained from fields subjected to: >50 years of cultivation of three perennial pasture grasses (i) Digitaria smutsii (DS), (ii) Brachiaria decumbens (BD), and (iii) Andropogon gayanus (AG); (iv) >50 years of continuous cultivation (CC) of cereals-legumes; and (v) >20 years of natural fallow (NF). The study was aimed at identifying the land-use system having optimal values for SPQ. Fields under CC had the highest bulk density, and the lowest total porosity (PORt) and macroporosity (PORp), field capacity (FC), and available water capacity (AWC). Perennial pasture grasses fields had significantly higher organic carbon, PORt, FC, AWC, and saturated hydraulic conductivity, and, hence, had better SPQ than CC fields and, in some instances, NF fields. The usefulness of ratios FC/PORt = 0.66 and ACt/PORt = 0.34 as additional indicators for assessing soil response to land-use systems was not proven in this study, and therefore, further studies should be conducted on the subject matter. Pasture grasses improved SPQ values relative to continuous cereal-legume cropping and fallow. The SPQ under CC and NF fields might be best improved by applying organic matter. Additional keywords: continuous cultivation, natural fallow, perennial pasture grasses, soil physical quality indicators., Introduction Soil physical quality degradation could lead to decline in crop performance and/or profitability, as well as causing negative environmental impacts (Wallace and Terry 1998). Continuous tillage has been reported [...]

Newly developed sensors have simplified real-time determination of soil water content ([θ.sub.m]). Although the TDR300 is one of the most recent dielectric sensors, little is known with regard to the accuracy and dependency of its measurements of soil type and other environmental factors. In this study, the performance of TDR300 was investigated using liquids of known dielectric properties and a set of porous media with textures ranging from sandy to clayey. The experiments were conducted in the laboratory by mixing different amounts of water with each soil to obtain a sufficient range of soil water contents. For sand, the calculated permittivity values ([ζ.sub.r]) correlated adequately with Topp's equation derived for time domain reflectometry. However, for the remaining inorganic porous media, [ζ.sub.r] values were overestimated compared with those resulting from Topp's equation, especially for water contents exceeding 0.2 [cm.sup.3]/[cm.sup.3]. The results suggested that the relationship between [θ.sub.m] and [square root of [ζ.sub.r]] was strongly linear (0.953 < [r.sup.2] 2dS/m, the relationship [θ.sub.m] - [square root of [ζ.sub.r]] was not linear, and, thus the TDR300 device calibration became increasingly difficult. Therefore, rather than operating as a time domain device, TDR300 operates as a water content reflectometer type device. Additional keywords: electrical conductivity, dielectric sensors, permittivity., Introduction Soil water content determination constitutes a significant parameter for optimising the management of soil-plant-atmosphere and hydrological systems. Time domain rcflectometry (TDR) is a reliable method for performing continuous, non-destructive [...]

Ecological communities are more than assemblages of species. In assessing the presence of many ecological communities, interpretation of soil properties and associated parent material has become a definitive component under environmental legislation worldwide, and particularly in Australia. The hypothesis tested here is that the geological parent material of a soil sample can be determined from particle size fraction data of the Marshall soil texture diagram. Supervised statistical classifiers were built from data for four particle-size fractions from four soil landscape publications. These methods were modified by taking into account possible autocorrelation between samples from the same site. The soil samples could not be classified with certainty as being derived from Wianamatta Group Shale or Hawkesbury Sandstone parent material. The classification of alluvial/fluvial-derived soils was no better than chance alone. A good classifier using four-fraction compositional data could not be built to determine geological parent material. Hence, the three size fractions of the Marshall soil texture diagram are insufficient to determine the geological parent material of a soil sample. Additional keywords: area under the curve (AUC), classifier, compositional data, geological parent material, receiver operating curve (ROC), soil particle size., Introduction Australian federal and state legislatures enshrined the concept of ecological communities within their laws as early as 1995 in New South Wales (NSW), and 1999 in Queensland and nationally [...]

The aim of soil mapping is to partition soil bodies using map units, which arc more homogenous for specific soil properties than arc the soil bodies as a whole. Soil properties arc expected to be similar at delineations of a specified soil map unit. Therefore, it is supposed that a model developed to estimate a soil property for one of these delineations could be generalised for the others. This study was conducted to determine the possibility of generalisation (extrapolation) of continuous models of spatial variability to estimate soil physical and chemical properties in similar delineations of a soil map unit. A consociation soil map unit in two different locations of a detailed soil map (1:20 000 scale), as similar delineations, was selected in the north-west of Faradonbch region, Iran. Sixty topsoil samples (0-20 cm) were randomly collected in each delineation (totally 120 samples) with 30-m intervals and the samples were GPS-recordcd. Laboratory studies consisted of bulk density, pH, calcium-carbonate equivalent, organic matter content, percentage of coarse fragments, and particle-size distribution. First, variography was done according to the soil data of each delineation (named areas A and B) and kriged maps were generated based on their own semivariogram parameters. Then, the kriged map of the soil properties for the second similar delineation (area B) was regenerated based on the corresponding models and their parameters obtained from the first similar delineation (area A). Finally, the regenerated kriged map of each variable was compared with its original kriged map. Visual comparison of the kriged maps of area B obtained from two steps of variography showed very high accordance for all of the soil properties. Quantitative comparison of the kriged maps suggests that the accuracy expected by the users of the soil information should be considered before generalisation of the data for similar units. Lower values of accordance obtained by the Kappa index and, especially, the classification success index than overall accuracy indicate that model generalisation should not be used where high precision of soil information is expected. Discrepancies observed for the kriged maps of the same variables in similar delineations could be due to different soil management practices in the past as a result of different historical developments. Additional keywords: continuous models, geostatistics, Kappa index, overall accuracy, soil map delineations., Introduction The idea of generalising (extrapolating) environmental variables was explored early (Prescott 1938), mainly to identify areas in the world with similar climates for crop production. The aim of soil [...]

Inherent characteristics of soil and land valuation data are used to examine the relationship between soil characteristics and rural farmland values to value soil natural capital in the 6000 [km.sup.2] Manawatu catchment in New Zealand. The study applies a widely used economic valuation method to determine whether the value of inherent characteristics of soils is reflected in land values. We find empirical evidence that the characteristics used to describe soil natural capital stock, e.g. gravel class, drainage class, potential rooting depth, and profile available water, are reflected in rural land values. Moreover, we find that these characteristics of soil stocks do not behave simply as independent variables but that there are complex relationships between them influencing their value. Additional keywords: hedonic prices, natural capital, rural land value, soil characteristics, value of soil., Introduction The concept of natural capital has evolved in recognition of the increased human influence and reliance on ecosystem goods and services (Crossman and Bryan 2009). Natural capital is commonly [...]

Few soil surveys in New South Wales have utilised international soil classifications. Extensive morphological and laboratory data collected during soil surveys in the Northern Rivers region provided a strong basis for correlation with the World Reference Base for Soil Resources (WRB), Soil Taxonomy (ST), and the Australian Soil Classification (ASC). Of the 32 reference soil groups comprising the WRB, 20 were present locally; nine of the 12 ST orders were present. After re-classification of soils, correlation of the ASC with the WRB and ST was undertaken. Soils not requiring extensive laboratory analysis for classification and sharing similar central concepts were the more straightforward to correlate. Several ASC orders have unique central concepts and were therefore difficult to correlate with any one WRB reference soil group or ST order/suborder. Other soils were difficult to correlate due to differences in definitions of similar diagnostic criteria. This is most applicable to soils with strong texture-contrast and those with natric conditions. Such soils are not adequately differentiated to suit the Northern Rivers conditions. Of the two international schemes, the WRB was easier to apply locally due to the relative simplicity of the scheme. Considering certain aspects of Australian soils would improve the applicability of the WRB as a truly international framework for soil classification and correlation. Amendments to both the ASC and WRB are suggested. Additional keywords: Australian Soil Classification, soil classification, soil correlation, soil survey., Introduction There are two modern soil classification systems that are generally regarded as having worldwide application--the World Reference Base (WRB) (IUSS Working Group WRB 2007) and the USDA Soil Taxonomy [...]

The chemical compositions of biochars from ten crop residues generated at 350°C and their effects on chemical properties of acid soils from tropical and subtropical China were investigated. There was greater alkalinity and contents of base cations in the biochars from legume residues than from non-legume residues. Carbonates and organic anions of carboxyl and phenolic groups were the main forms of alkalis in the biochars, and their relative contributions to biochar alkalinity varied with crop residues. Incubation experiments indicated that biochar incorporation increased soil pH and soil exchangeable base cations and decreased soil exchangeable acidity. There were greater increases in soil pH and soil exchangeable base cations, and a greater decrease in soil exchangeable acidity, for biochars from legume than from nonlegume residues. The biochars did not increase the cation exchange capacity (CEC) of soils with relatively high initial CEC but did increase the CEC of soils with relatively low initial CEC at an addition level of 1%. The incorporation ofbiochars from crop residues not only corrected soil acidity but also increased contents of potassium, magnesium, and calcium in these acid soils from tropical and subtropical regions and thus improved soil fertility. Additional keywords: alkalinity, amelioration of acid soils, base cations, biochar, CEC, crop residues., Introduction Oxygen-limited pyrolysis (partial or total absence of oxygen) of plant-derived biomass yields biochar, a solid, carbon-rich residue (Sohi et al. 2010). Producing biochars from agricultural residues can reduce accumulation [...]

In the northern agricultural region of Western Australia, some farmers have integrated C4 grass pastures into their fanning system. This switch away from a farming system historically dominated by annual species could alter soil nutrient and carbon (C) levels. To explore this issue, 16 'over-the-fence', pair-wise comparisons were conducted between a field in an annual crop-pasture rotation and a field sown to perennial pasture. The perennial pastures were 2-8 years of age, and comprised a mix of perennial species and volunteer annuals. Soils were deep yellow sand (Tenosols), and perennial root systems extended to beyond 150 cm. Averaged over all sites, organic C (OC) in the top 90cm of the profile was 38.7 t/ha, nitrate 34.5 kg/ha, Colwell phosphorus (P) 5.9 kg/ha, and Colwell potassium (K) 518 kg/ha. In general, there were no differences between annuals and perennials for any of these attributes. For OC, greater differences were observed between sites than between annual and perennial species. Site differences in OC ranged from 18.7 to 62.7 t/ha. There were some differences between annuals and perennials at different sites for OC, P, nitrate, and K, but these differences were not systematic. For example, at three sites, more OC was found in the annual system; at another site, more OC was found in the perennial system, and differences occurred in the surface layers at two sites and at depth in the other two. Overall, clear differences between annual and perennial farming systems were not evident and were highly variable. The survey was augmented with a simulation study using the APSIM crop model, where a continuous perennial pasture was compared with a wheat-wheat-lupin rotation. After 10 years, there was only 1.27 t/ha more OC in the perennial system than the annual. The simulation study and on-farm survey suggest the differences in the accumulation of soil C under a perennial or an annual system in this landscape are small and variable, and if differences do exist, they will take considerable time to accrue. In addition, management and local site effects were more important than the perenniality of the system per se in influencing C and nutrient levels., Introduction There is a growing interest in the contribution that perennial pastures can make to profitability and sustainability of mixed crop-livestock systems in Australia (Ewing and Flugge 2004; Lefroy et [...]

We investigated the changes in stand structure, species composition, and soil characteristics of jack pine (Pinus banksiana Lamb.) disjunct stands on the southern shore of Lake Michigan in North America. Our NMS (Non-metric Multidimensional Scaling) ordination revealed a chronosequence of the succession from jack pine stand to black oak (Quercus velutina Lam.) woodland. A majority of jack pine seedlings appeared to be recruited near wet pannes (shallow intradunal ponds with standing water) where the water table was relatively high, expanded in dry pannes, and followed by invasions of black oak and other upland tree species on dune ridges. Expansion of canopy cover, along with dominance of black oak, have likely led to a major reduction in herbaceous cover and a shift in the composition of the understory species. Species richness and diversity have increased. However, much of the increase was attributed to species that were not native to the Lake Michigan sand dunes. Soil pH and nitrogen concentration changed significantly from the younger wet panne to the older dune ridge plots, but other measures of soil fertility did not differ among the plots. The reduction in soil pH in the older plots was likely due to the neutralization of calcareous soil by carbonic acid leached from accreted sands and organic acids produced by litter decomposition. Nitrogen accumulation in the soil is expected to continue beyond the equilibrium values predicted from mature oak woodland soil. Jack pine seedlings have been documented to be tolerant of xeric conditions. However, we found that seedling survival was over five times higher in moist soil near the wet pannes. In this respect, failure in formation of new pannes may reduce the size of the region's jack pine population in the foreseeable future., INTRODUCTION Jack pine (Pinus banksiana Lamb.) is widely distributed in fire-prone boreal forest in the northern latitudes of North America (Schoenike, 1962; Rudolph and Laidly, 1990; Asselin et al., 2003). [...]

Comparative studies of soil quality and energy use in two- and three-crop rotations in irrigated cotton (Gossypium hirsutum L.) based cropping systems under varying stubble management practices in Australian Vertosols are sparse. Our primary objective was to quantify selected soil quality indices (salinity, sodicity, exchangeable cations, nitrate-N, pH), crop yields, and greenhouse gas emissions in four irrigated cotton-based cropping systems sown on permanent beds in a Vertosol with subsoil sodicity near Narrabri in north-western New South Wales. A secondary objective was to evaluate the efficacy of sowing vetch in rotation with cotton over a long period on the incidence of black root-rot in cotton seedlings. Results presented in this report pertain to the period June 2005-May 2011. The experimental treatments were: cotton cotton; cotton-vetch (Vicia benghalensis L.); cotton-wheat (Triticum aestivum L.), where wheat stubble was incorporated; and cotton wheat-vetch, where wheat stubble was retained as in-situ mulch. Vetch was terminated during or just before flowering by a combination of mowing and contact herbicides, and the residues were retained as in-situ mulch. Soil pH, electrical conductivity (E[C.sub.1:5]), [Cl.sup.-], N[O.sub.3.sup.-]-N, exchangeable cations, exchangeable sodium percentage (ESP), electrochemical stability index (= E[C.sub.1:5]/ESP), and E[C.sub.1:5]/ESC (exchangeable sodium concentration) were evaluated in samples taken from the 0-1.2 m depth before sowing cotton during late September or early October of each year. Incidence of black root-rot was assessed 6 weeks after sowing cotton. Compared with sowing cotton every year, including wheat in cotton-based cropping systems improved cotton yield and reduced soil quality decline, emissions of carbon dioxide equivalents (C[O.sub.2]-e) per unit area, and C[O.sub.2]-e emissions per unit of cotton yield. Including vetch in the rotation was of negligible benefit in terms of yield and C[O.sub.2]-e emissions per unit of yield. The rate of soil quality decline was unaffected by including vetch in a cotton--wheat rotation but was accclerated when included in a cotton--cotton sequence. Among all cropping systems, soil quality was best with cotton-wheat and cotton--wheat-vetch but poorest with cotton-vetch. Although C[O.sub.2]-e emissions associated with growing 1 ha of cotton could be reduced by 9% by growing vetch because of substituting fixed atmospheric N for N fertiliser derived from fossil fuels, this advantage was partly negated by the emissions from farming operations associated with growing a vetch crop. Relative to a two-crop rotation (one cotton--one rotation crop), negligible benefits in terms of yield, soil quality, greenhouse gas emissions, and black root-rot control accrued from a three-crop rotation (one cotton-two rotation crops). Incidence of black root-rot increased as the number of cotton crops sown increased. In addition to the cropping systems, soil quality indices and yield were significantly influenced by irrigation water quality and climate. Additional keywords: Haplustert, mulch, permanent bed, rotation, wheat, Vertisol, vetch., Introduction Cropping systems under which irrigated cotton (Gossypium hirsutum L.) is grown in Australian Vertosols can be broadly classified into three groups: (i) cotton monoculture, where cotton is sown continuously [...]

Invasive species usurp habitat space at the expense of natives, reducing biodiversity and altering ecosystem function. The non-native invasive shrub Amur honeysuckle (Lonicera maackii) is known to have substantial effects on forest structure and biodiversity in Midwestern North America; however, its influence on nutrient cycling is relatively unexplored. We investigated throughfall volume and chemistry, and soil nutrients, under and away from L. maackii shrubs in random locations along transects in three patchily invaded second-growth forests. Significantly lower volumes of throughfall were found under L. maackii canopies than in sites located away from L. maackii. Cation concentrations in throughfall were significantly higher, and in some instances 3 x higher, under L. maackii than in 'away' locations. Despite lower throughfall volumes under L. maackii compared to 'away' locations, total deposition of cations in throughfall under L. maackii was also consistently higher than in adjacent areas of native forest canopy. In contrast, [NH.sub.4.sup.+]-N concentrations in throughfall were significantly lower under L. maackii than away, suggesting N transformation and assimilation as rainwater passed through the canopy. No differences were found in soil properties between 'under' and 'away' locations. In summary, L. maackii significantly reduced the volume of rainwater arriving at the forest floor and altered the chemistry of that rainwater causing an increase in cation concentrations and a reduction in [NH.sub.4.sup.+]-N. These results suggest that L. maackii invasion has the potential to cause significant alterations to nutrient cycling in forests., INTRODUCTION The invasion of forests by non-native species can substantially influence ecosystem composition and function (Evans et al., 2001; Mack et al., 2000). Invasive species rapidly expand into habitat space, [...]

To better understand the long-term effects of species selection and forest management practices on soil quality and soil C retention, we analyzed soil samples from an experimental planting of loblolly (Pinus taeda L.), longleaf (Pinus palustris Mill.), and slash (Pinus elliottii Engelm.) pines under different management intensities in Mississippi. The treatments included stump removal and cultivation (CULT), a one-time application of fertilizer combined with stump removal and cultivation (CULT+F), and a control (CON). After 49 years, pine species had no significant effect on any soil physical or chemical parameter examined, despite species differences in basal area. CULT exhibited significantly higher soil bulk density and lower soil C and soil N than CON and CULT+F in the upper 10 cm of soil. Stump removal is not a common practice in southern pine silviculture today; however, as demand for bioenergy fuels or feedstocks increases, more complete biomass utilization will be considered. Residual stumps play an important role in soil nutrient and C retention in pine plantations. Our results show that stump removal can lead to reduced soil C (-21%) and soil N (-35%) compared with controls, although it is possible to mitigate nutrient losses on poor sites with fertilization. Resume: Dans le but de mieux comprendre les effets a long terme du choix des especes et des pratiques d'amenagement forestier sur la qualite du sol et la retention du C, nous avons analyse des echantillons de sol provenant de plantations experimentales de pin a encens (Pinus taeda L.), de pin des marais (Pinus palustris Mill.) et de pin d'Elliott (Pinus elliottii Engelm.) soumises a differentes intensites d'amenagement au Mississippi. Les traitements incluaient l'enlevement des souches et des pratiques culturales (CULT), une application unique de fertilisant combinee a l'enlevement des souches et a des pratiques culturales (CULT+F) et un traitement temoin (CON). Apres 49 ans, les especes de pin n'avaient pas d'effet significatif sur aucun des parametres physiques ou chimiques du sol qui ont ete etudies malgre les differences de surface terriere entre les especes. Dans les premiers 10 cm de sol, la densite apparente du sol etait plus grande et la teneur en C et N du sol etait plus faible dans le traitement CULT que dans les traitements CON et CULT+F. L'enlevement des souches n'est pas une pratique courante de la sylviculture actuelle des pins du sud. Cependant, a mesure que la demande pour la biodiversite et les matieres premieres augmente, une utilisation plus complete de la biomasse sera envisagee. Les souches residuelles jouent un role important dans la retention de C et des nutriments dans le sol des plantations de pin. Nos resultats montrent que l'enlevement des souches peut entrainer une diminution de C (-21 %) et de N (-35 %) dans le sol comparativement au traitement temoin bien qu'il soit possible d'attenuer les pertes de nutriments dans les stations pauvres par la fertilisation. [Traduit par la Redaction], Introduction Intensive silviculture is employed to enhance seedling survival, improve tree quality, and increase stand productivity. This may be through practices that improve site conditions for tree growth or in [...]

Although litterfall respiration [(R.sub.L]) is a key process of soil carbon dynamics in forests, factors that drive [R.sub.L] and its contribution to soil respiration [(R.sub.S]) have not been sufficiently studied. Using a litter removal method, we researched [R.sub.L] and the ratio of [R.sub.L]:[R.sub.S] in a 20-year-old exotic slash pine (Pinus elliottii Englem.) plantation in subtropical China. Soil temperature explained 67%, 78%, and 25% of variation in [R.sub.S], mineral soil respiration ([R.sub.S-L]), and [R.sub.L], respectively, but had little impact on [[R.sub.L]:R.sub.S]. To study influences besides temperature, measured [R.sub.S] and [R.sub.S-L] were normalized using the Arrhenius equation. Even though this subtropical plantation was characterized by a humid climate with abundant precipitation, a rainfall pulse induced increase in soil moisture primarily drove [R.sub.L] and its contribution to [R.sub.S] but depressed [R.sub.S-L]. The response of [R.sub.L] to rainfall and soil moisture was significantly more sensitive than that of [R.sub.S-L]. Furthermore, the effects of rainfall and soil moisture on [R.sub.S], [R.sub.L], and [R.sub.L]:[R.sub.S] were higher during the dry season (July-December) than during the wet season (January-June). In the context of climate change, [R.sub.L] and its contribution to [R.sub.S] are expected to decrease because of the predicted decrease in rainfall amount and frequency in subtropical regions. Resume: Bien que la respiration de la litiere [(R.sub.L]) soit un processus cle de la dynamique du carbone dans le sol des forets, les facteurs qui controlent [R.sub.L] et sa contribution a la respiration du sol ([R.sub.S]) n'ont pas suffisamment ete etudies. A l'aide d'une methode d'enlevement de la litiere, nous avons etudie [R.sub.L] et le rapport [R.sub.L]:[R.sub.S] dans une plantation exotique de pin d'Elliott (Pinus elliottii Engelm.) en zone subtropicale chinoise. La temperature du sol expliquait respectivement 67 %, 78 % et 25 % de la variation de [R.sub.S], de la respiration dans le sol mineral [(R.sub.S-L]) et de [R.sub.L] mais avait peu d'impact sur le rapport [R.sub.L]: [R.sub.S]. Pour etudier les sources d'influence autres que la temperature, les valeurs de [R.sub.S] et [R.sub.S-L] ont ete normalisees a l'aide de l'equation d'Arrhenius. Meme si cette plantation subtropicale etait caracterisee par un climat humide avec des precipitations abondantes, l'augmentation de l'humidite du sol causee par les episodes de pluie etait le principal facteur qui controlait [R.sub.L] et sa contribution a [R.sub.S] mais faisait diminuer [R.sub.S-L]. La reponse de [R.sub.L] a la pluie et a l'humidite du sol etait significativement plus sensible que celle de [R.sub.S-L]. De plus, les effets de la pluie et de l'humidite du sol sur [R.sub.S], [R.sub.L] et [R.sub.L]:[R.sub.S] etaient plus prononces durant la saison seche (juillet a decembre) que durant la saison humide (janvier a juin). Dans le contexte des changements climatiques, [R.sub.L] et sa contribution a [R.sub.S] devraient diminuer a cause de la diminution prevue de la quantite de pluie et de sa frequence dans les regions subtropicales. [Traduit par la Redaction], Introduction Globally, forests cover about a quarter of the terrestrial surface and contain about 1146 Pg of carbon, of which over two thirds of this carbon is stocked in the [...]

: To test the hypothesis that seedling growth and water use increase with soil temperature and improved soil area Ton and vary with species, we evaluated the above- and below-ground growth and water use of seedlings of four northern boreal conifer species: black spruce (Pica Mariana (Mill.) B.S.P.), white spruce (Pica glace (Munch) Voss), tamarack (Larynx larrikin (Due Rio) K. Koch), and lodge pole pine (Pinups contort Doug. ex Loud.) grown under different temperature And near-flooded soil conditions. Seedlings were grown in specialized pots that maintained the water table level at either 15 cm (high water table treatment: very wet) or 30 cm (low water table treatment: moderately wet) below the soil surface, and whole-seedling transpiration was assessed. Soil temperature (5, 10, or 20°C) was controlled with a water bath surrounding the pots. Although some species were sensitive to the high water table treatment, soil temperature was the driver of seedling growth and water use. We ranked the ability of the seedlings of the species to tolerate the cold soil conditions examined as black spruce > lodgepole pine > tamarack > white spruce. The ranking of the ability to tolerate near-flooded conditions was tamarack and lodgepole pine > black spruce > white spruce. Resume: Pour tester l'hypothese que la croissance et l'utilisation de l'eau par les semis augmentent avec la temperature dusol et une meilleure aeration du sol, nous avons evalue la croissance aerienne et souterraine et l'utilisation de l'eau par les semis de quatre especes boreales de conifere: l'epinette noire (Picea mariana (Mill.) B.S.P.), l'epinette blanche (Picea glauca (Moench) Voss), le meleze laricin (Larix laricina (Du Roi) K. Koch) et le pin tordu (Pinus contorta Dougl. exLoud.) cultives a differentes temperatures dans un sol quasi inonde. Les semis ont ete cultives dans des pots speciaux qui maintenaient le niveau de la nappe phreatique soit a 15 cm (niveau de la nappe phreatique eleve: tres humide, soit a 30 cm (niveau de la nappe phreatique bas: moderement humide) sous la surface du sol et la transpiration globale des semis a ete mesuree. La temperature du sol (5, 10 ou 20°C) etait controlee par un bassin d'eau qui contenait les pots. Bien que certai-nes especes fussent sensibles au traitement niveau de la nappe phreatique eleve, la temperature du sol etait le facteur qui de-terminait la croissance des semis etl'utilisation de l'eau. Nous avons classe les differentes especes selon leur capacite a tolerer des conditions de temperature du sol plus froides. On retrouve dans l'ordre de l'espece la plus tolerante a la moins tolerante: l'epinette noire, le pin tordu, le meleze laricin et l'epinette blanche. De la meme facon, selon leur capacite a tole-rer des conditions de quasi-inondation, on retrouve sur le meme pied, le meleze laricin et le pin tordu suivis de l'epinette noire et de l'epinette blanche. [Traduit par la Redaction], Introduction In the boreal plain of North America, many forest sites are located on low-lying areas with flat topography and soils of poor internal drainage. In combination with the cold [...]

Soil quality is a major issue in the southeastern United States because the sandy, eroded soils there have few of the nutrients and organic matter that crops need. Moreover, climate [...]

Byline: G. Khola and U. Hanif ABSTRACT Soil samples collected from an archaeological site Gulabi Bagh Lahore to evaluate pollen morphology and type of pollen present in the surface soil [...]

Byline: Z. I. Khan, K. Ahmad, M. Sher, Z. Hayat, A. Hussain, A. Seidavi and Y. Rizwan ABSTRACT To assess the transport of lead (Pb) in soil-plant-animal continuum, a study [...]

Byline: F. Budak, T. Tukel and R. Hatipoglu ABSTRACT This study was carried out during growing seasons of 2001 and 2002 in Eskisehir to investigate the possibility of growing various [...]

Byline: A. Mojiri, A. Jalalian and N. Honarjoo - Email: amin.mojiri@gmail.com ABSTRACT This study evaluated the effects of soil properties on growth of Haloxylon sp. in Segzi plain in the [...]

Efforts to bring chemical fertilizers to sub-Saharan Africa are often met with concerns over harmful environmental and economic side effects. The products improve soil quality--useful in Africa, where soils often [...]

The problems facing agriculture today are numerous and daunting. How do we maintain the quality of our soils? How do we provide a sufficient supply of food and fiber as [...]

Decades of plowing throughout the Piedmont region of the United States have degraded the soil, allowing much of it to be washed away and robbing what is left of nutrients [...]