Showing papers in "Soil Science in 2016"

A Review of Silicon in Soils and Plants and Its Role in US Agriculture: History and Future Perspectives

Abstract: Abstract Silicon (Si) is the second most abundant element in the earth’s crust and plays a number of important roles in the mineral nutrition of plants. In the past 20 years, the scientific documentation on the benefits of Si to crops has helped establish Si fertilization as an agronomic practice in many agricultural lands worldwide. However, very little information has been consolidated on the use of Si specifically for US agriculture. Consequently, the objectives of this review are to provide (1) information on the dynamics of Si in soil, use, and sources; (2) a history and up-to-date documentation on Si-related research in many areas of US production agriculture; and (3) perspectives on Si as a plant beneficial nutrient and the potential of Si fertilization as an agronomic practice in US crop production systems. The Si-driven mechanisms enhancing the productivity of a wide array of crops under stressed conditions are discussed in this review. Based on the recent 10-year average production level and published shoot Si content, the principal crops grown in the United States can collectively take up 9.55 million tons of Si annually, whereas the annual Si removal rate for the entire US cropland area is estimated at 21.1 million tons. On the basis of this projected annual Si removal rate, adoption of continuous intensive farming systems in the country, low solubility of soil Si, and complex chemical dynamics of Si in soil, increasing plant-available Si levels through fertilization is therefore foreseen a logical agronomic practice for US agriculture.

Ecosystem engineers in a self-organized soil: A review of concepts and future research questions

Abstract: Soils are self-organized ecological systems within which organisms interact within a nested suite of discrete scales. Microorganisms form communities and physical structures at the smallest scale (microns), followed by the community of their predators organized in microfoodwebs (tens of microns), the functional domains built by ecosystem engineers (centimeters to meters), ecosystems, and landscapes. Ecosystem engineers, principally plant roots, earthworms, termites, and ants, play key roles in creating habitats for other organisms and controlling their activities through physical and biochemical processes. The biogenic, organic, and organomineral structures that they produce accumulate in the soil space to form three-dimensional mosaics of functional domains, inhabited by specific communities of smaller organisms (microfauna and mesofauna, microorganisms) that drive soil processes through specific pathways. Ecosystem engineers also produce signaling and energy-rich molecules that act as ecological mediators of biological engineering processes. Energy-rich ecological mediators may selectively activate microbial populations and trigger priming effects, resulting in the degradation, synthesis, and sequestration of specific organic substrates. Signaling molecules inform soil organisms of their producers' respective presences and change physiologies by modifying gene expression and through eliciting hormonal responses. Protection of plants against pests and diseases is largely achieved via these processes. At the highest scales, the delivery of ecosystem services emerges through the functioning of self-organized systems nested within each other. The integrity of the different subsystems at each scale and the quality of their interconnections are a precondition for an optimum and sustainable delivery of ecosystem services. Lastly, we present seven general research questions whose resolution will provide a firmer base for the proposed conceptual framework while offering new insights for sustainable use of the soil resource.

Termites: The Neglected Soil Engineers of Tropical Soils

Abstract: Termites are undoubtedly key soil organisms in tropical and subtropical soils. They are soil engineers in influencing the physical, chemical, and biological properties of soils and, consequently, water dynamics in tropical and subtropical ecosystems. To appreciate the effect of termites on soil, there is a need for a thorough understanding of the ecological needs and building strategies of termites and the mechanisms regulating termite diversity at local and regional scales. Termite impacts on soil properties and water dynamics can be differentiated at four different scales: (i) at the landscape scale, where termites act as heterogeneity drivers; (ii) at the soil profile scale, where termites act as soil bioturbators; (iii) at the aggregate scale, where they act as aggregate reorganizers; (iv) and last, at the clay mineral scale, where they can act as weathering agents. Last, we discuss recent literature on termite engineering published in the last 10 years in the major journals of soil science and suggest new research topics that could contribute to improved knowledge of the impact of termites on soil properties and water dynamics.

Characterization of Biochars and Their Use as an Amendment to Acid Soils

Abstract: Biochar, because of its porous nature, calcium carbonate (CaCO3) equivalent, surface functional groups, and other properties, could serve as an acid soil amendment. To investigate the liming potential of biochars, laboratory characterization and greenhouse and field experiments were conducted in Hawaii and West Java, Indonesia, respectively. Six wood-derived biochars were characterized and amended to a Hawaiian acid soil (pH 4.6, exchangeable aluminum [Al] 1.8 cmolc kg) at 2% and 4% alone or in combination with 2 cmolc kg of lime and then planted with Desmodium intortum (a forage legume sensitive to Al) twice in a greenhouse trial. To the Indonesian acid soils (pH 3.9–4.0, exchangeable Al 8–14 cmolc kg), a rice husk and a lac tree biochars at 4% and 8% alone or in combination with lime at 4 and 8 cmolc kg and compost at 0.1 and 0.2% were applied and then planted with soybean (Glycine max) cv. Anjasmoro twice in field trials. Biochar effects on soil properties and plant growth were measured. The results indicated that the six biochars varied in pH, ash content, CaCO3 equivalent, total basic cations, cation exchange capacity, and other properties (pore size, surface functional groups). Soil pH was increased, soil exchangeable Al was reduced, and plant nutrients were enriched to different degrees upon additions of biochars. Total dry weights of Desmodium were increased 2- to 4-fold over the control or lime treatment upon applications of biochar. Similar effects on soils and soybean were obtained for the Indonesian field trials. It was concluded that CaCO3 equivalent and total basic cations were among the most important properties of biochar responsible for improving acid soil productivity and plant growth.

Relationships Between Soil Carbon and Soil Texture in the Northern Great Plains

Abstract: Abstract The amount of carbon (C) sequestered in soil is related to soil texture, soil management, vegetation, and climatic variation. However, in the Northern Great Plains, little information is available to quantify the effects of soil texture on the C sequestration potential of soils. This work was conducted to develop relationships for C sequestration potential based on soil texture under a variety of agricultural practices. Soil samples were collected from central and southeast North Dakota from sites with differing soil management and cropping systems; this includes native prairie, differing Conservation Reserve Program year classes, no-till, and conventional tillage practices. Particle size analysis was determined on the 0- to 15-cm soil depth using a hydrometer method. Sand fractions were determined by sieving. Carbon analysis was done by a high temperature combustion method. For all sampled soils, total silt (%) was found to be positively correlated (P ⩽ 0.01) to organic C content (percent organic C) and organic C mass (kg m−2 depth−1). Sand was found to be negatively correlated (P ⩽ 0.10) with % organic C and organic C mass. Soil clay content was correlated with organic C mass (P ⩽ 0.05) but not percent organic C. Bulk density was found to be negatively correlated with percent organic C (P ⩽ 0.10). The strong correlation between silt content and soil organic C reflects the greater water holding capacity and plant available water of silt-dominated soils, which, in turn, affect plant productivity and influences C sequestration in soil.

Burrowing Through the Literature: The Impact of Soil-Disturbing Vertebrates on Physical and Chemical Properties of Soil

Abstract: Soil-disturbing vertebrates (SDV) are relatively low in biodiversity and biomass compared with the dominant soil fauna (microorganisms and invertebrates), but they can nevertheless have a great impact on the physical and chemical properties of soils. Our goal is to take an ichnological (organism-substrate interactions)–based approach to review the impacts of SDV on soils; these impacts result in three basic categories of physical structures (traces): subterranean excavations, constructed surficial mounds, and surficial excavations and depressions. We focus on direct rather than indirect effects and frame these in terms of soil additions, losses, translocations, and transformations. We look at publication trends in the SDV literature and graphically summarize examples of maximum reported construction heights, excavation depths, and volumes of soil displacement for various SDV. We then review SDV impacts on soil color, texture, horizonation, structure, bulk density, soil moisture, porosity and permeability, organic matter, pH, cation exchange capacity, and the nutrients Ca, Mg, N, K, P, S, and Si. Translocations are common sources of variation in these properties and may be especially important in creating nutrient-rich patches in otherwise limited landscapes. Common results of SDV activity include destruction of soil structure, decreases in bulk density, and increases in infiltration rates, porosity, and permeability. Additions of excrement and plant material are important sources of organic matter, N, and K. Direct soil losses may occur through geophagy and trampling and wallowing behaviors. Erosion is an important indirect impact often related to killing of surface vegetation from mounding and foraging behaviors.

Soil animals and pedogenesis : the role of earthworms in anthropogenic soils

Abstract: The role of earthworms as one of the most important groups of ecosystem engineers in human-modified and natural environments has been increasingly recognized only during the last 30 years, yet earthworms and humans have been acting together in building landscapes for millennia. This relationship is well represented in the pre-Columbian raised fields, in flood-prone savannas around the rim of Amazonia, but also by the potentially significant role of earthworms in the formation and resilience of Amazonian Dark Earths. Through the bioturbating action of earthworms, soil is biologically, chemically, and physically altered; nutrients are translocated; organic matter is decomposed and transformed; and the surrounding biota interacts as a large orchestra where the soil musicians play together on the various instruments but where earthworms take a leading role, enhancing microbial activity and generally stimulating plant growth. In this article, we assess the remarkable role of earthworms at the center of soil pedogenetic processes within anthropogenic landscapes, dissecting their functions with a special focus on Amazonian Dark Earths.

Effects of Biochar Produced From Sugarcane Bagasse at Different Pyrolysis Temperatures on Water Retention of a Calcaric Dark Red Soil

Abstract: Biochar (BC) is a promising soil amendment that can enhance water retention and plant-available water capacity while mitigating CO2 emissions. We investigated the effect of sugarcane bagasse–derived BC on the water retention properties of a calcaric clay soil amended with 3% (wt/wt) BC produced at three pyrolysis temperatures (400°C, 600°C, and 800°C). For BC pyrolyzed at 800°C (BC800), water retention curves of soil amended at 1%, 5%, and 10% (wt/wt) were also measured. Water retention curves were measured immediately after amending soil with BC (all types and rates) and after a 180-day incubation period for soils amended with 3% BC. The hydrophobicity of BC pyrolyzed at 400°C (B400) was the highest of the three temperatures tested, resulting in the lowest water retained in soil amended with BC400, but only for measurements done before incubation. During incubation, the hydrophobicity of B400 decreased as the aliphatic compounds became exhausted by oxidation of the BC surfaces. The available water capacity of the clay soil increased significantly by more than 60% when amended with BC at rates greater than of 3% wt/wt (P < 0.05).

Long-term Management Effects on Soil Properties and Yields in a Wheat-Soybean Double-Crop System in Eastern Arkansas

Abstract: Abstract The sustainability of soil and water resources in regions of highly productive row-crop agriculture depends on long-term implications of agricultural management decisions. Residue management can strongly affect soil organic matter (SOM), soil C, and other near-surface physical and chemical properties in agricultural soils, especially in double-crop systems. The objective of this study was to determine the long-term trends in SOM, soil C and N, bulk density, pH, electrical conductivity, and Mehlich-3–extractable nutrients in the top 10 cm and yield as affected by alternative residue and water management practices in a wheat (Triticum aestivum L.)-soybean (Glycine max (L.) Merr.) double-crop production system. The field site resides on a loessial soil (fine silty, mixed, active, thermic Glossaquic Fraglossudalf) in the Lower Mississippi River Alluvial Valley of eastern Arkansas and has been consistently managed for 13 years between Fall 2001 and Fall 2014. Averaged across all other treatment factors, SOM content did not change (P > 0.05) between 6 and 13 years after conversion to alternative management practices under irrigation, whereas SOM content increased across time (P < 0.05) until approximately 9 years after initial conversion then decreased thereafter under dryland production. Soil C content generally increased, P content generally decreased, and N and Cu contents and soybean yields changed little across time because of irrigation. Across time, SOM and C contents decreased (P < 0.05) under residue burning but increased under nonburning. The results of this study indicate that irrigation management and residue burning were responsible for many of the largest differences in near-surface soil property trends across time. Understanding the long-term effects of alternative, compared with traditional, management practices is critical to developing sustainable agricultural practices in the mid-southern United States.

Evaluation of Alternative Management Practices With the AnnAGNPS Model in the Carapelle Watershed

Abstract: The Annualized Agricultural Non-point Source (AnnAGNPS) model can be used to analyze the effects of management practices on sediment loads in agricultural watersheds. The study was performed in a 506 km2 Mediterranean watershed located in Apulia, Southern Italy, planted with mostly winter wh

Current state of peatland soils as an effect of long-term drainage – preliminary results of peatland ecosystems investigation in the Grójecka Valley (central Poland)

Abstract: Abstract Understanding the effect of long-term drainage of peatland areas is helpful in future peatland management and regulations of water conditions. The aim of this work was to assess the current state of fen peatland soils in the Grójecka Valley (eastern part of the Wielkopolskie voivodeship, central Poland), affected by long-term agricultural use (pastures, meadows) since the 1960s and potentially by lignite open pit mining industry (KWB Konin) since 1980s. Field studies were carried out in 2015 in selected fen peatland areas. Soil material for laboratory analysis was collected from genetic horizons from four soil profiles. The surface horizons of studied organic and organo-mineral soils were built with well-developed moorsh material. They were classified as medium moorshiefied – MtII (profile 1, 3 and 4) and strongly moorshiefied – MtIII (profile 2). Obtained results of physical and physico-chemical analysis indicate that long-term peatland utilization connected with potential impact of the lignite mining, transformed mainly the upper horizons of studied organic and organo-mineral soils. However, despite obvious strong human impact on peatlands ecosystems, we cannot exclude the climate variables, what should be confirmed by long-term monitoring program. Furthermore, presented paper indicated that new subtype moorsh-muddy soils (in Polish: gleby murszowo-mułowe) within the type of gleyic soils should be implemented in the next version of Polish Soil Classification.

Correlation between the Polish Soil Classification (2011) and international soil classification system World Reference Base for Soil Resources (2015)

Abstract: Abstract The recent editions of the Polish Soil Classification (PSC) have supplied the correlation table with the World Reference Base for Soil Resources (WRB), which is the international soil classification most commonly used by Polish pedologists. However, the latest WRB edition (IUSS Working Group WRB 2015) has introduced significant changes and many of the former correlations became outdated. The current paper presents the closest equivalents of the soil orders, types and subtypes of the recent edition of the PSC (2011) and WRB (IUSS Working Group WRB 2015). The proposals can be used for general correlation of soil units on maps and in databases, and may support Polish soil scientists to establish the most appropriate equivalents for soils under study, as well as make PSC more available for an international society.

Proposal of English equivalents for the soil taxa names in the Polish Soils Classification

Abstract: Abstract The article presents proposed English translations of all names of soil units (orders, types and subtypes) listed by Polish Soils Classification, PSC (2011). The proposal has been elaborated based on the recent Polish and foreign literature, using uniform and consistent criteria. Due to the lack of soil names translation in the recent, fifth edition of PSC, the suggested English nomenclature was basically derived from the previous, fourth edition of PSC (1989). However, significant amendment and numerous additions to the latest version were proposed. A uniform and comprehensive system of soil taxa translations may help to avoid nomenclature chaos in the English papers of Polish authors, which intentionally base or refer to PSC.

Selection of “Local” Models for Prediction of Soil Organic Matter Using a Regional Soil Vis-NIR Spectral Library

Abstract: Abstract Soil spectral libraries have been established as a reference for predicting soil properties by visible and near-infrared (Vis-NIR) spectroscopy. Numerous studies show that predictions of soil properties over a local area can be improved by selecting an appropriate “local” subset from a large library; although these have usually been geographically local, they can be local in other than the geographic sense. We investigated prediction of soil organic matter at a local site using a regional soil Vis-NIR spectral library with 1,365 samples. Models built using the entire library were compared with subsets selected by (i) parent material (Cali_pm), (ii) land use type (Cali_lu), (iii) material-land use combination (Cali_com), and (iv) spectral similarity (Cali_ss). Models were built by partial least-squares regression, and their performances were evaluated using two independent test sets, one for paddy field (Test_paddy) and another one for upland agriculture (Test_up). Prediction accuracy was measured by the ratio of percentage deviation (RPD) compared with models built on the entire library. Ratios of percentage deviation for Cali_lu increased from 1.58 to 1.65 (Test_up) and from 2.05 to 3.02 (Test_paddy); for Cali_ss, RPD increased from 1.58 to 1.89 (Test_up) and from 2.05 to 2.26 (Test_paddy). Cali_pm models performed well for Test_paddy (RPD = 2.76) but poorly for Test_up (RPD = 1.11). Cali_com models used the fewest number of samples and performed poorly for both test sets (RPD < 1.5). These results show the potential of using land use types or spectral similarity to select “local” models for prediction of soil organic matter using a regional spectral library.

Climate-Induced Shifts in Global Soil Temperature Regimes

Abstract: Soil temperature is a key factor of plant growth and biological enzyme activities occurring in the soil, affected by the land cover, the evapotranspiration rate, the albedo, and the energy budget of the soil surface. In recent decades, efforts have been made to conserve soils against nonsust

Modeling Soil Salinity in Greenhouse Cultivations Under a Changing Climate With SALTMED: Model Modification and Application in Timpaki, Crete

Abstract: Soil salinity is a major soil degradation threat especially for arid coastal environments where it hinders agricultural production, thus imposing a desertification risk. In the prospect of a changing climate, soil salinity caused by brackish water irrigation introduces additional uncertainti

Semiarid Watershed Response to Low-Tech Porous Rock Check Dams

Abstract: Rock check dams are used throughout the world to mitigate erosion problems on degraded lands. Many restoration efforts on rangelands in the southwestern United States incorporate such structures; however, their impact on watershed response and channel morphology is not well quantified. In 20

Biochar as a soil amendment

Abstract: Abstract Biochar is a carbonaceous product of biomass pyrolysis under limited oxygen conditions. Due to the very good sorption properties material is used as a soil amendment. In recent years, much attention has been paid to biochar as a potential tool improving soil properties and fertility. The most important benefits of its use in agriculture is a significant increase of sorption capacity, reduced nutrient leaching, as well as slow release of macro- and microelements essential for plant growth, liming effect, increased water holding capacity, improved biological properties, resulting in an increase in crop yields. The aim of the study is to summarize the knowledge about the impact of biochar on soil environment, as well as identify areas and directions for future research on biochar application in soils impacted by human activities

Earthworm and Enchytraeid Co-occurrence Pattern in Organic and Conventional Farming: Consequences for Ecosystem Engineering

Abstract: Abstract Earthworms and enchytraeids are ecosystem engineers with an important influence on soil structure maintenance and nutrient cycling. We investigated if different agricultural managements produce a replacement of earthworms by enchytraeids, the magnitude of that replacement, and its effect on ecosystem engineering activities. Organic farming with plough tillage (ORG), conventional farming with plough tillage, conventional farming with no-tillage (NT), and unmanaged natural grasslands were studied. Earthworms and enchytraeids were sampled by means of extracting and hand sorting soil monoliths. Soil bulk density, mechanical resistance, organic matter content, and litter decomposition were measured as indicators of soil structure maintenance and nutrient cycling. A negative relation between earthworm and enchytraeid abundances was confirmed, not related to tillage intensity. Competitive interactions between them are suggested. Among agricultural systems, ORG had the highest earthworm abundance and NT had the highest enchytraeids abundance and the highest enchytraeid-to-earthworm ratio. Besides, intermediate abundances of earthworms and enchytraeids promoted by ORG were related to soil structure indicators' values similar to grassland and enhanced litter decomposition process. Despite a higher abundance of enchytraeids in NT, both soil structure maintenance and nutrient cycling indicators had worse values than those in ORG.

Nitrogen mineralization in forestry-drained peatland soils in the Stołowe Mountains National Park (Central Sudetes Mts)

Abstract: Abstract The aim of this work was to determine the intensity of nitrogen mineralization in forestry drained ombrotrophic peatland soils in the Stołowe Mountains National Park, SW Poland. Additionally discussion about the shallow organic soils classification according to Polish Soil Classification (2011) is presented. For the study three research transects were established on forestry drained ombrotrophic peatlands in the Stołowe Mountains. Each of the transect consisted of four (site A and B) or five (site C) sampling plots. Sampling was conducted in the year 2012. The soil samples for the basic soil properties analysis were sampled in April, whereas undisturbed soil samples were collected in stainless steel rings (100 cm3) every 10 cm in April (spring), July (summer) and October (autumn) to show the seasonal dynamics of nitrogen mineralization. Statistical analysis showed that the content of N-NH4 was mainly determined by actual soil moisture and precipitation rate, whereas the content of N-NO3 was positively correlated with air temperature. Among investigated peatlands the highest concentrations of mineral nitrogen forms was observed in the Długie Mokradło bog, situated on the Skalniak Plateau-summit. Additionally, the results obtained showed that implementation of new subtype: shallow fibric peat soils (in Polish: gleby torfowe fibrowe płytkie) within the type of peat soils (in polish: gleby torfowe) should be considered during developing of the next update of Polish Soil Classification.

Influence of Agroforestry Buffers on Soil Hydraulic Properties Relative to Row Crop Management

Abstract: Abstract Agroforestry and grass buffers have been developed as part of the management system for row crop areas in temperate regions to improve soil and water quality and diversify farm income. A study was conducted to evaluate the influence of agroforestry and grass buffers relative to row crop management on soil hydraulic properties (saturated hydraulic conductivity, soil water retention, and pore size distribution) for a claypan soil. The experimental watersheds for this project were located at the Greenley Memorial Research Center. The paired watersheds for the study area were under no-till management with a corn (Zea mays L.)–soybean (Glycine max L.) rotation since 1991. The agroforestry buffer watershed and grass buffer watershed had vegetative buffer strips planted between row crop areas, which were 4.5 m wide and 36.5 m apart with vegetation composed of grasses, legumes, and trees. Throughout the grass buffer and agroforestry buffer strips, redtop (Agrostis gigantea Roth), brome grass (Bromus spp.), and birdsfoot trefoil (Lotus corniculatus L.) were planted. For the agroforestry buffers, pin oak (Quercus palustris Muenchh), swamp white oak (Quercus bicolar Willd.), and bur oak (Quercus macrocarpa Michx.) trees were planted. Soil cores were taken from four 10-cm depth increments with 6 replicates, and hydraulic and physical properties were determined. Significant differences (P < 0.05) were found among the treatments for bulk density, with the row crop treatment having higher values compared with the buffer treatments. Trends also showed higher saturated hydraulic conductivity for the agroforestry buffer treatment compared with the row crop treatment for the 0 to 10 cm and 30 to 40 cm soil depths. These buffer treatments slightly improved soil hydraulic properties after 17 years for this claypan soil.

The Effect of the Soil Properties on Adsorption, Single-Point Desorption, and Degradation of Chlorpyrifos in Two Agricultural Soil Profiles From Colombia

Abstract: Abstract Structural composition of soil organic matter and the adsorption/desorption characteristics of the insecticide chlorpyrifos were investigated in two soil profiles (Andisol and Entisol) under agriculture production using Fourier transform infrared spectroscopy, nuclear magnetic resonance, and batch analysis methods. Throughout the soil profile, the Andisol had larger values of pH, organic carbon content, cation exchange capacity (CEC), and effective CEC than the Entisol. The Entisol showed larger amounts of kaolinite and ferric and/or aluminum oxides in deeper soil layers. Soil organic matter carbonyl-C, aryl-C, O-alkyl C, and alkyl-C were transported vertically in the vadose zone, with aryl-C being the predominant species in both soils. These results suggest that aryl-C is a reasonable predictor of chlorpyrifos adsorption properties under tropical conditions. Chlorpyrifos adsorption was found to be spontaneous and exothermic, with decreasing adsorption values of the distribution coefficient Kd (37.2–10.1 L kg−1) in the deeper layers of both soil types (although more significant in the Entisol). One-step desorption hysteresis showed a monotonic decrease with increasing soil depth and correlated positively with both organic carbon and CEC. The degradation of chlorpyrifos in Andisol (0–100 cm) was investigated using a laboratory incubation method. Degradation rate k was found to be approximately constant (0.011–0.015 d−1) throughout the soil profile where biotic and abiotic processes are active. Based on the Groundwater Ubiquity Score, chlorpyrifos presented a “transitional” leaching potential with soil depth.

Effects of Nitrogen Addition on Potential Soil Nitrogen-Cycling Processes in a Temperate Forest Ecosystem

Abstract: Abstract Anthropogenic nitrogen (N) deposition substantially alters N cycling in terrestrial ecosystems because of its effects on soil physicochemical properties and soil microbes. Responses of N transformation processes to consecutive N additions are unclear, pointing to a lack of systematic understanding of N cycling under long-term N addition. This work combines 15N tracing laboratory incubation with the FLUAZ model to study potential gross N-cycling processes in a temperate forest ecosystem in eastern Asia after 6 years of consecutive N additions at a rate of 50 kg N ha−1 year−1. Soils from plots that received N additions had greater gross N mineralization probably because of higher soil carbon (C) and N than soils from control plots. Gross nitrification in soil from plots receiving N additions was inhibited likely because of lower pH in these plots. Higher NH4+ concentrations under N addition increased N immobilization by microbes, but NO3− immobilization was much lower than NH4+ immobilization. Our results also show that N remineralization was stimulated by N addition and that microbes in N addition plots had greater N uptake probably because they adapted to high N concentration that led to accelerated microbial N turnover rate. This research highlights the importance of considering the effects of increasing N deposition on N processes mediated by microbes.

Forms and mobility of trace elements in soils of park areas from the city of Bydgoszcz, north Poland

Abstract: Abstract Increasing human activity affects urban ecosystem, including soils. The objective of the study were examine the content of lead, cadmium, copper, zinc, and manganese in soils of city parks and green areas from Bydgoszcz agglomeration, north Poland, estimate their forms and mobility, characterize distribution within soil profile, and estimate their origin – anthropogenic or natural. Three green areas from the older part of the city were selected for the study. Multistep sequential extraction method was conducted for the separation of seven metal fractions. It is concluded that soil studied were contaminated mainly by zinc and lead. These metals exist mainly in relatively non mobile forms i.e. associated with amorphous and crystalline iron oxides and with soil organic matter. The distribution within soil depth varied due to the elution process and variation of mixed soil material and additives.

Evidence for Losses From Strongly Bound SOM Pools After Clear Cutting in a Northern Hardwood Forest

Abstract: Forest soils in the northeastern United States store considerable amounts of carbon (C). With the increasing utilization of biomass as a “C-neutral” form of energy in the United States, these forests are susceptible to clear cutting and large losses of soil organic matter (SOM) to the atmosp

Is Soil Water Potential a Reliable Variable for Irrigation Scheduling in the Case of Peach Orchards

Abstract: Monitoring the crop water status of high-value crops such as fruit trees is generally performed through periodic measurements of physiological indicators on leaves or fruits using sophisticated instruments and complex procedures. These measurements are very often difficult to translate into

Characterization of Methane Emissions From Rice Production on a Clay Soil in Arkansas

Abstract: Rice (Oryza sativa L.) production systems have a greater global warming potential than upland crops because of methane (CH4) emissions resulting from anaerobic conditions of the flooded soils. Differences in cultural practices, cultivar choice, previous crop/crop rotation, and in particular

Variability of soil properties in an intensively cultivated experimental field

Abstract: Abstract The aim of the study was to determine whether long-term intensive cultivation that used variable ploughing and fertilisation technologies and schemes influences the differentiation of soil properties which may impact the results of growing experiments in a relatively small experimental field (0.1 ha). The field under study is located in Wrocław, in an agricultural experimental station that has been operating for more than 60 years. A transformation of rusty gleyic soils (Brunic Gleyic Arenosols) into anthropogenic black earths (Gleyic Phaeozems (Arenic)) was noticed. The content of organic carbon and nitrogen, pH and the content of exchangeable base cations in the plough layer were positively (statistically and spatially) correlated and their increased values were observed in soils with a deeper and darker plough level. The present differentiation of the physical and chemical properties of soils in the experimental field do not result from such primary soil-forming factors as a kind and texture of parent material, topography, moisture regime, or (micro-)climatic conditions, which are not differentiated within the field, but from various intensity of former cultivation on individual sections of the experimental field. The variability cśfficient of the crucial soil properties was found to exceed 30%, which might significantly influence the results of micro-plot vegetation experiments.

The effect of municipal sewage sludge on the chemical composition of spring barley

Abstract: Abstract Due to the fact that soils in Poland are mostly light soils, there is a need to improve their physical, chemical and biological properties. In addition, as a result of the decrease in the number of farm animals, a decrease in production of natural fertilizers can be observed. Low production of natural fertilizers speaks in favor of agricultural use of municipal sewage sludge in Poland. Municipal sewage sludge is composed of large quantities of macronutrients necessary for plants. This waste also contains significant amounts of organic substance. Chemical properties, including a high content of nitrogen, phosphorus, and often calcium, speak in favor of environmental use of municipal sewage sludge. Increasing requirements with respect to environmental protection cause the necessity to assess the effects of using organic waste for fertilization. In a farm located in the commune of Iwanowice (Małopolska province), municipal sewage sludge was applied under spring barley cultivation. The soil on which municipal sewage sludge was applied was classified into the category of heavy soils with neutral reaction. When assessing the content of available nutrients (P, K, Mg) in the soil, their low content was determined. After application of municipal sewage sludge in a dose of 24 Mg fresh matter per hectare, which corresponded to 5.34 Mg DM·ha−1, under spring barley, beneficial changes in chemical properties of the soil were observed. An increase in soil abundance in organic carbon and total nitrogen was observed, as well as an increase in the content of available forms of phosphorus, potassium and magnesium. Based on the results of the conducted chemical analyses, it was established that biomass of spring barley fertilized with sewage sludge contained more macronutrients (N, P, K, Na, Ca and Mg), which improved its feed value. The field experiment showed that application of municipal sewage sludge increased uptake of macronutrients by spring barley.

Estimation of Soil Texture at a Regional Scale Using Local Soil-Landscape Models

Abstract: Abstract This study investigated the feasibility of extrapolating soil-landscape data from predictive soil maps. Artificial neural network (ANN) and random forest (RF) were used to predict sand and clay content in the poorly accessible area of Qilian Mountains. Six regular matrices consisting of 4 × 4 samples were selected as independent validation. Eleven calibration data sets of different sizes were grouped on the basis of field observations and external soil data. All the predictive models were trained 100 times, and average mean error, root mean square error, and coefficient of determination (R2) were used as validation accuracy. After selecting predictors based on stepwise regression, their relative importance was assessed by removing them from the prediction and evaluating results by increases of root mean square errors and mean decreased accuracy in ANN and RF models, respectively. Furthermore, the uncertainty propagated from two watershed soil maps was quantified by predicting SD of each grid cell from 100 realizations of ANN models. Results suggest that 30 to 32% of the topsoil texture variation was explained by the extrapolating approach and that external soil data moderately enhanced the prediction performance. However, increasing the size of the calibration data set did not increase accuracy. The contributions of the predictors were more significant in the RF model than the ANN model. Uncertainty analysis revealed biases introduced from the external data. More watershed soil maps might be necessary for a robust and accurate extrapolation at a regional scale.