scholarly journals Solutions for subsidence in the California Delta, USA, an extreme example of organic-soil drainage gone awry

2020 ◽  
Vol 382 ◽  
pp. 837-842
Author(s):  
Steven J. Deverel ◽  
Sabina Dore ◽  
Curtis Schmutte
Keyword(s):  
Organic Matter ◽  
Water Supply ◽  
Greenhouse Gas ◽  
Greenhouse Gas Emission ◽  
Animal Feed ◽  
Organic Matter Content ◽  
Organic Soil ◽  
Organic Soils ◽  
Human Consumption ◽  
Land Uses

Abstract. The Sacramento-San Joaquin Delta is at the heart of California's water supply system that provides water for irrigation and human consumption. It is also home to subsiding organic soils, decreasing native aquatic species populations, water quality degradation, vulnerable levees (levees are equivalent to dikes) and decreasing agricultural viability. There has been substantial progress in the interdisciplinary understanding and quantification of the nature and effects of subsidence and its mitigation. Because of the need for a drained rootzone, farming of crops such as vegetables, trees, vines, corn and alfalfa, results in an ongoing unsustainable cycle of continuing peat oxidation and deepening of drainage ditches to compensate for elevation loss. Despite substantial evidence for the increasing risks to the State's economy and water supply, the unsustainability of the status quo, and evidence for the benefits of alternatives, there has been limited progress in converting to land uses that can reduce, stop and reverse subsidence. Our overall approach has been to measure land-surface elevation changes; understand, quantify and model subsidence and greenhouse gas emissions from drained organic soil, and evaluate alternate land uses. Subsidence rates vary from less than 0.5 to over 2 cm yr−1, depending primarily on depth to groundwater and soil organic matter content. The primary cause of subsidence is the oxidation of organic matter, which has resulted in elevations of −3 to −9 m on about 100 000 ha. Using the results from micrometeorological measurements and modelling, we estimate that organic-matter oxidation causes an annual emission of over 2×106 t of CO2-equivalent which represents about 21 % of the State's plant-based agricultural emissions. Rewetting of the peat soils is emerging as a viable solution. Rice and wetlands stop and (in the case of wetlands) reverse the effects of subsidence and result in a net greenhouse-gas emission reduction benefit. Wetlands accrete about 3 cm of soil per year, can break the unsustainable subsidence/drainage cycle, reverse the trajectory of increasing hydraulic pressures on levees, reduce the probability of levee failure and seepage onto islands (islands are equivalent to polders), and may provide material for biofuels and animal feed. The recent implementation of a methodology for quantification of the GHG benefit is facilitating land use conversion and participation in the carbon market.

scholarly journals A fertile peatland forest does not constitute a major greenhouse gas sink

2013 ◽  
Vol 10 (11) ◽  
pp. 7739-7758 ◽  
Author(s):  
A. Meyer ◽  
L. Tarvainen ◽  
A. Nousratpour ◽  
R. G. Björk ◽  
M. Ernfors ◽  
...  
Keyword(s):  
Greenhouse Gas ◽  
Eddy Covariance ◽  
Organic Matter Content ◽  
C Sequestration ◽  
Organic Soil ◽  
Organic Soils ◽  
Indirect Approach ◽  
Short Period ◽  
N2o Fluxes ◽  
C Assimilation

Abstract. Afforestation has been proposed as a strategy to mitigate the often high greenhouse gas (GHG) emissions from agricultural soils with high organic matter content. However, the carbon dioxide (CO2) and nitrous oxide (N2O) fluxes after afforestation can be considerable, depending predominantly on site drainage and nutrient availability. Studies on the full GHG budget of afforested organic soils are scarce and hampered by the uncertainties associated with methodology. In this study we determined the GHG budget of a spruce-dominated forest on a drained organic soil with an agricultural history. Two different approaches for determining the net ecosystem CO2 exchange (NEE) were applied, for the year 2008, one direct (eddy covariance) and the other indirect (analyzing the different components of the GHG budget), so that uncertainties in each method could be evaluated. The annual tree production in 2008 was 8.3 ± 3.9 t C ha−1 yr−1 due to the high levels of soil nutrients, the favorable climatic conditions and the fact that the forest was probably in its phase of maximum C assimilation or shortly past it. The N2O fluxes were determined by the closed-chamber technique and amounted to 0.9 ± 0.8 t Ceq ha−1 yr−1. According to the direct measurements from the eddy covariance technique, the site acts as a minor GHG sink of −1.2 ± 0.8 t Ceq ha−1 yr−1. This contrasts with the NEE estimate derived from the indirect approach which suggests that the site is a net GHG emitter of 0.6 ± 4.5 t Ceq ha−1 yr−1. Irrespective of the approach applied, the soil CO2 effluxes counter large amounts of the C sequestration by trees. Due to accumulated uncertainties involved in the indirect approach, the direct approach is considered the more reliable tool. As the rate of C sequestration will likely decrease with forest age, the site will probably become a GHG source once again as the trees do not compensate for the soil C and N losses. Also forests in younger age stages have been shown to have lower C assimilation rates; thus, the overall GHG sink potential of this afforested nutrient-rich organic soil is probably limited to the short period of maximum C assimilation.

scholarly journals A fertile peatland forest does not constitute a major greenhouse gas sink

2013 ◽  
Vol 10 (3) ◽  
pp. 5107-5148 ◽  
Author(s):  
A. Meyer ◽  
L. Tarvainen ◽  
A. Nousratpour ◽  
R. G. Björk ◽  
M. Ernfors ◽  
...  
Keyword(s):  
Greenhouse Gas ◽  
Eddy Covariance ◽  
Organic Matter Content ◽  
C Sequestration ◽  
Organic Soil ◽  
Organic Soils ◽  
Optimum Growth ◽  
Indirect Approach ◽  
Short Period ◽  
N2o Fluxes

Abstract. Afforestation has been proposed as a strategy to mitigate the often high greenhouse gas (GHG) emissions from agricultural soils with a high organic matter content. However, the carbon dioxide (CO2) and nitrous oxide (N2O) fluxes after afforestation can be considerable, depending predominantly on site drainage and nutrient availability. Studies on the full GHG budget of afforested organic soils are scarce and hampered by the uncertainties associated with methodology. In this study we determined the GHG budget of a spruce-dominated forest on a drained organic soil with an agricultural history. Two different approaches for determining the net ecosystem CO2 exchange (NEE) were applied: for the year 2008, direct (eddy covariance) and an indirect (analyzing the different components of the GHG budget), so that uncertainties in each method could be evaluated. The annual tree production in 2008 was 8.2 (± 1.7)t C ha–1yr–1 due to the high levels of soil nutrients, the favorable climatic conditions and the fact that the forest was in its optimum growth phase. N2O fluxes were determined by the closed chamber technique and amounted to 3.3 (± 2.4) t CO2eq ha–1 yr–1. According to the direct measurements from the eddy covariance technique, the site acts as a minor GHG sink of −4.1 (± 2.6) t CO2eq ha–1 yr–1. This contrasts with the NEE estimate derived from the indirect approach which suggests that the site is a net GHG emitter of 3.3 (± 10.1)t CO2eq ha–1 yr–1. Irrespective of the approach applied, the soil CO2 effluxes counter large amounts of the C sequestration by trees. Due to major uncertainties involved in the indirect approach, the direct approach is considered the more reliable tool. As the site was in its optimum growth stage, i.e. the rate of C sequestration was at its maximum and will decrease with forest age, it will probably become a GHG source once again as the trees mature. Since forests in their younger stages are usually GHG sources or have no effect on GHGs, the overall sink potential of this afforested nutrient-rich organic soil is probably limited to only a short period.

Field dissipation of S-metolachlor in organic and mineral soils used for sugarcane production in Florida

2019 ◽  
Vol 34 (3) ◽  
pp. 362-370
Author(s):  
Jose V. Fernandez ◽  
D. Calvin Odero ◽  
Gregory E. MacDonald ◽  
Jason A. Ferrell ◽  
Brent A. Sellers ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Moisture ◽  
Linear Trend ◽  
Organic Matter Content ◽  
Field Studies ◽  
Matter Content ◽  
Organic Soils ◽  
Sugarcane Production ◽  
Mineral Soils ◽  
Moisture Conditions

AbstractDissipation of S-metolachlor, a soil-applied herbicide, on organic and mineral soils used for sugarcane production in Florida was evaluated using field studies in 2013 to 2016. S-metolachlor was applied PRE at 2,270 g ha−1 on organic and mineral soils with 75% and 1.6% organic matter, respectively. The rate of dissipation of S-metolachlor was rapid on mineral soils compared with organic soils. Dissipation of S-metolachlor on organic soils followed a negative linear trend resulting in half-lives (DT50) ranging from 50 to 126 d. S-metolachlor loss on organic soils was more rapid under high soil-moisture conditions than in corresponding low soil-moisture conditions. On mineral soils, dissipation of S-metolachlor followed an exponential decline. The DT50 of S-metolachlor on mineral soils ranged from 12 to 24 d. The short persistence of S-metolachlor on mineral soils was likely attributed to low organic matter content with limited adsorptive capability. The results indicate that organic matter content and soil moisture are important for persistence of S-metolachlor on organic and mineral soils used for sugarcane production in Florida.

Humus, nitrogen and energy balances, and greenhouse gas emissions in a long-term field experiment with compost compared with mineral fertilisation

Soil Research ◽  
2016 ◽  
Vol 54 (2) ◽  
pp. 254 ◽  
Author(s):  
Eva Erhart ◽  
Harald Schmid ◽  
Wilfried Hartl ◽  
Kurt-Jürgen Hülsbergen
Keyword(s):  
Organic Matter ◽  
Field Experiment ◽  
Greenhouse Gas ◽  
Ghg Emissions ◽  
Organic Matter Content ◽  
C Sequestration ◽  
Organic C ◽  
Soil C ◽  
Positive Balance ◽  
Energy Balances

Compost fertilisation is one way to close material cycles for organic matter and plant nutrients and to increase soil organic matter content. In this study, humus, nitrogen (N) and energy balances, and greenhouse gas (GHG) emissions were calculated for a 14-year field experiment using the model software REPRO. Humus balances showed that compost fertilisation at a rate of 8 t/ha.year resulted in a positive balance of 115 kg carbon (C)/ha.year. With 14 and 20 t/ha.year of compost, respectively, humus accumulated at rates of 558 and 1021 kg C/ha.year. With mineral fertilisation at rates of 29–62 kg N/ha.year, balances were moderately negative (–169 to –227 kg C/ha.year), and a clear humus deficit of –457 kg C/ha.year showed in the unfertilised control. Compared with measured soil organic C (SOC) data, REPRO predicted SOC contents fairly well with the exception of the treatments with high compost rates, where SOC contents were overestimated by REPRO. GHG balances calculated with soil C sequestration on the basis of humus balances, and on the basis of soil analyses, indicated negative GHG emissions with medium and high compost rates. Mineral fertilisation yielded net GHG emissions of ~2000 kg CO2-eq/ha.year. The findings underline that compost fertilisation holds potential for C sequestration and for the reduction of GHG emissions, even though this potential is bound to level off with increasing soil C saturation.

scholarly journals Organic carbon determination in histosols and soil horizons with high organic matter content from Brazil

2006 ◽  
Vol 63 (2) ◽  
pp. 187-193 ◽  
Author(s):  
Marcos Gervasio Pereira ◽  
Gustavo Souza Valladares ◽  
Lúcia Helena Cunha dos Anjos ◽  
Vinícius de Melo Benites ◽  
Ademar Espíndula Jr. ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Organic Matter Content ◽  
Analysis Data ◽  
Matter Content ◽  
Organic Soils ◽  
Organic Carbon Content ◽  
Muffle Furnace ◽  
Soil Taxonomy ◽  
High Organic Carbon Content

Soil taxonomy systems distinguish mineral soils from organic soils based on the amount of soil organic carbon. Procedures adopted in soil surveys for organic carbon measurement are therefore of major importance to classify the soils, and to correlate their properties with data from other studies. To evaluate different methods for measuring organic carbon and organic matter content in Histosols and soils with histic horizons, from different regions of Brazil, 53 soil samples were comparatively analyzed by the methods of Walkley & Black (modified), Embrapa, Yeomans & Bremner, modified Yeomans & Bremner, muffle furnace, and CHN. The modified Walkley & Black (C-W & B md) and the combustion of organic matter in the muffle furnace (OM-Muffle) were the most suitable for the samples with high organic carbon content. Based on regression analysis data, the OM-muffle may be estimated from C-W & B md by applying a factor that ranges from 2.00 to 2.19 with 95% of probability. The factor 2.10, the average value, is suggested to convert results obtained by these methods.

HUMIC-FULVIC ACID RELATIONSHIPS IN ORGANIC SOILS AND HUMIFICATION OF THE ORGANIC MATTER IN THESE SOILS

1967 ◽  
Vol 47 (3) ◽  
pp. 245-250 ◽  
Author(s):  
M. Schnitzer
Keyword(s):  
Molecular Weight ◽  
Organic Matter ◽  
Humic Acid ◽  
Fulvic Acid ◽  
Oxidative Degradation ◽  
Fulvic Acids ◽  
Organic Soil ◽  
Organic Soils ◽  
Salting Out ◽  
Naoh Solution

Twenty organic-soil samples of widely differing degrees of decomposition were extracted with 0.5 N NaOH solution under N2. Amounts of humic and of fulvic acids in the acidified extracts did not correlate significantly with pyrophosphate solubilities. This was thought to be due to interference in the separation scheme by relatively large amounts of ash constituents in the extracts. Since the "classical" fractionation of soil organic matter appears to involve essentially the "salting out" of higher molecular-weight humic from lower molecular-weight fulvic acids, an excessively high salt concentration during the separation should be avoided.To lower the concentration of inorganic constituents in the extracts, the samples were first pretreated with dilute HCl–HF solution and then extracted with 0.1 N NaOH rather than with 0.5 N NaOH. Under these conditions, amounts of fulvic acids in the acidified extracts showed a significant positive correlation (r = 0.52) with pyrophosphate solubilities of untreated extracts, whereas amounts of humic acids in the extracts exhibited a highly negative correlation (r = −0.57) with pyrophosphate solubilities. In the soils examined, increased humification was associated with increases in fulvic-acid but decreases in humic-acid concentrations.From the results of this and of earlier investigations done in this laboratory it appeared that the main mechanism governing humification in these soils was oxidative degradation, resulting ultimately in the formation of fulvic from humic acid.

scholarly journals Organic Matter Causes Chemical Pollutant Dissipation Along With Adsorption and Microbial Degradation

2021 ◽  
Vol 9 ◽  
Author(s):  
A. Vilhelmiina Harju ◽  
Ilkka Närhi ◽  
Marja Mattsson ◽  
Kaisa Kerminen ◽  
Merja H. Kontro
Keyword(s):  
Organic Matter ◽  
Microbial Degradation ◽  
Mineral Soil ◽  
Organic Soil ◽  
Organic Soils ◽  
First Response ◽  
Chemical Pollutant ◽  
Mineral Soils ◽  
Soil And Sediment

Views on the entry of organic pollutants into the organic matter (OM) decaying process are divergent, and in part poorly understood. To clarify these interactions, pesticide dissipation was monitored in organic and mineral soils not adapted to contaminants for 241 days; in groundwater sediment slurries adapted to pesticides for 399 days; and in their sterilized counterparts with and without peat (5%) or compost-peat-sand (CPS, 15%) mixture addition. The results showed that simazine, atrazine and terbuthylazine (not sediment slurries) were chemically dissipated in the organic soil, and peat or CPS-amended soils and sediment slurries, but not in the mineral soil or sediment slurries. Hexazinone was chemically dissipated best in the peat amended mineral soil and sediment slurries. In contrast, dichlobenil chemically dissipated in the mineral soil and sediment slurries. The dissipation product 2,6-dichlorobenzamide (BAM) concentrations were lowest in the mineral soil, while dissipation was generally poor regardless of plant-derived OM, only algal agar enhanced its chemical dissipation. Based on sterilized counterparts, only terbutryn appeared to be microbially degraded in the organic soil, i.e., chemical dissipation of pesticides would appear to be utmost important, and could be the first response in the natural cleansing capacity of the environment, during which microbial degradation evolves. Consistent with compound-specific dissipation in the mineral or organic environments, long-term concentrations of pentachloroaniline and hexachlorobenzene were lowest in the mineral-rich soils, while concentrations of dichlorodiphenyltrichloroethane (DTT) and metabolites were lowest in the organic soils of old market gardens. OM amendments changed pesticide dissipation in the mineral soil towards that observed in the organic soil; that is OM accelerated, slowed down or stopped dissipation.

scholarly journals Strength characteristics of artificial organic soils stabilized with copolymer stabilizer

2018 ◽  
Vol 169 ◽  
pp. 01010 ◽  
Author(s):  
Chia-Wen Law ◽  
Felix Ngee-Leh Ling ◽  
Boon-Khiang Ng
Keyword(s):  
Organic Matter ◽  
Organic Soil ◽  
Organic Soils ◽  
Chemical Stabilization ◽  
Test Device ◽  
Compressive Test ◽  
Acid Ratio ◽  
Strength Material ◽  
Strength Increment ◽  
Effective Stabilization

Organic soil is known as low strength material, and chemical stabilization is widely used to increase its bearing capacity. However, the use of traditional stabilizer has some limitations. Therefore, stabilization was carried out by using non-traditional stabilizer - Vinyl acetate-ethylene (VAE) copolymer emulsion in this study with the aim to determine its suitability to stabilize soil mixed with organic matter. Two types of artificial organic soil with kaolin: organic acid ratio of 5:5 (K5HA5) and 7:3 (K7HA3) were utilized. Control specimens were tested using pure kaolin. Different percentages of VAE (5%, 7.5%, 10%) were added in order to determine the minimum amount of stabilizer required to achieve a minimum strength increment of a 345 kPa. The strength of samples was determined with automated unconfined compressive test device. Specimens were air cured for 7 days prior to testing. Both K7HA3 with 7.5% VAE and K5HA5 with 10% VAE had achieved the minimum strength increment to be considered as effective stabilization. The strength of the artificial organic soil was found to be increasing with the increment of percentages of VAE used. Hence, it can be concluded that stabilizing mechanism of the artificial organic soils with VAE is not affected by organic matter.

Evaluation of Contributing Factors on Strength Development of Lime Stabilized Artificial Organic Soils Using Statistical Design of Experiment Approach

2014 ◽  
Vol 905 ◽  
pp. 362-368 ◽  
Author(s):  
Felix N.L. Ling ◽  
Khairul Anuar Kassim ◽  
Ahmad Tarmizi Abdul Karim ◽  
S.C. Ho
Keyword(s):  
Organic Matter ◽  
Statistical Design ◽  
Organic Soil ◽  
Curing Temperature ◽  
Organic Soils ◽  
Strength Development ◽  
Test Results ◽  
Contributing Factors ◽  
Strength Enhancement ◽  
Factor Interactions

Lime is widely used as chemical stabilizer in soft soil stabilization. However, lime is reported to be less effective when dealing with organic soil. It is believed that the organic matter in the soil will retard the pozzolanic reaction which is responsible for strength enhancement. The heterogeneity nature of the organic matter in the soil makes the study complicated and reduced the repeatability of the test results. Hence, artificial organic soil with known organic matter and content are preferred by researchers when repeatability of the test results are required in determining the influential effect of each contribution factor. Various factors such as additive contents, effect of aging (curing periods), curing temperature, density of materials and moisture content are reported by previous researchers as the potential contributing factors towards the strength development. It is believed that the interaction of the factors also will contribute to the strength enhancement. Hence, this study is carried out to evaluate the contributing factors and its interactions on strength development of artificial organic soils with known type and contents of organic matter. Statistical design of experiment (DOE) approach was utilized to evaluate the factors and its interaction on the strength development of lime stabilized artificial organic soils by using commercial statistics package. Three main factors were investigated: effect of organic content, effect of curing periods, and effect of additive, while other factors namely curing temperature, molding water content, types of compaction and compactive effort were keep constant through controlled experiments. Processed kaolin (inorganic material) is mixed with humic acid (organic matter) to simulate the organic soil which comprised of inorganic soil and organic matter. The density of the soil specimen and its moisture content were recorded before and after the curing process. General Linear Model (GLM) was utilized to determine the significance of the main factors, two-factor interactions, and three factor interactions. The significance factors and interactions were utilized in multiple regression analysis to develop the strength prediction model which can be utilized to predict the strength of stabilized materials within the inference space defined by the experiment.

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