Carbon Sequestration In Agricultural Soils Research Articles

Soil carbon sequestration is a climate stabilization wedge: Comments on Sommer and Bossio (2014)

Sommer and Bossio (2014) model the potential soil organic carbon (SOC) sequestration in agricultural soils (croplands and grasslands) during the next 87 years, concluding that this process cannot be considered as a climate stabilization wedge. We argue, however, that the amounts of SOC potentially sequestered in both scenarios (pessimistic and optimistic) fulfil the requirements for being considered as wedge because in both cases at least 25 GtC would be sequestered during the next 50 years. We consider that it is precisely in the near future, and meanwhile other solutions are developed, when this stabilization effort is most urgent even if after some decades the sequestration rate is significantly reduced. Indirect effects of SOC sequestration on mitigation could reinforce the potential of this solution. We conclude that the sequestration of organic carbon in agricultural soils as a climate change mitigation tool still deserves important attention for scientists, managers and policy makers.

Changes in soil organic carbon and nitrogen as affected by tillage and residue management under wheat–maize cropping system in the North China Plain

The importance of soil organic carbon (SOC) and nitrogen (N) sequestration in agricultural soils as climate-change-mitigating strategy has received robust attention worldwide in relation to soil management. This study was conducted to determine the temporal effects of different tillage systems and residue management on distribution, storage and stratification of SOC and N under wheat (Triticum aestivum L.) – maize (Zea mays L.) cropping systems in the North China Plain (NCP). Four tillage systems for winter wheat established in 2001 were: moldboard plow tillage with maize residues removed (PT0), moldboard plow tillage with maize residues incorporated (PT), rotary tillage with maize residues incorporated (RT), and no-till with maize residues retained on the soil surface (NT). Compared with PT0 and PT, significantly higher SOC and N concentrations were observed in the surface layer (0–10cm depth) under NT and RT. In 2004, the SOC stocks were lower (P<0.05) under NT and RT than under PT and PT0, however, the opposite trend was observed in 2012. Compared with 2001, the net profile (0–30cm) SOC sequestration rate was 10.60, 13.95, 13.65, and 14.92Mgha−1 in 2012 under PT0, PT, RT, and NT, respectively. As for SOC stocks in the 0–50cm profile, no significant differences (P<0.05) were observed among NT, RT, and PT. The trends in N stocks in profile (0–30, 0–50cm depth) were NT>RT>PT>PT0 in both years. Compared with other treatments, SOC and N stocks were the lowest (P<0.05) under PT0. Therefore, crop residues play an important role in SOC and N management, and improvement of soil quality. The higher SOC stratification was observed under NT and RT than under PT and PT0, whereas the C:N ratio was higher (P<0.05) under PT and PT0 than under NT and RT systems. Therefore, the notion that NT leads to higher SOC stocks than plowed systems requires cautious scrutiny. Nonetheless, some benefits associated with NT present a greater potential for its adoption in view of the long-term environmental sustainability under wheat–maize double-cropping system in the NCP.

The potential for carbon sequestration in Australian agricultural soils is technically and economically limited

Concerns about increasing concentrations of greenhouse gases in the atmosphere, primarily carbon dioxide (CO2), have raised worldwide interest in the potential of agricultural soils to be carbon (C) sinks. In Australia, studies that have quantified the effects of improved management practices in croplands on soil C have generally been inconclusive and contradictory for different soil depths and durations of the management changes. We therefore quantitatively synthesised the results of Australian studies using meta-analytic techniques to assess the technical and economic feasibility of increasing the soil C stock by improved management practices. Our results indicate that the potential of these improved practices to store C is limited to the surface 0–10 cm of soil and diminishes with time. None of these widely adopted practices is currently financially attractive under Australia's new legislation known as the Carbon Farming Initiative.

Modeling topsoil carbon sequestration in two contrasting crop production to set-aside conversions with RothC – Calibration issues and uncertainty analysis

Model simulations of soil organic carbon turnover in agricultural fields have inherent uncertainties due to input data, initial conditions, and model parameters. The RothC model was used in a Monte Carlo based framework to assess the uniqueness of solution in carbon sequestration simulations. The model was applied to crop production to set-aside conversions in Iowa (sandy clay-loam soil, humid-continental climate) and Greece (clay-loam soil, Mediterranean). The model was initialized and calibrated with particulate organic carbon data obtained by physical fractionation. The calibrated values for the Iowa grassland were 5.05tCha−1, 0.34y−1, and 0.27y−1 for plant litter input and decomposition rate constants for resistant plant material (RPM) and humus, respectively, while for the Greek shrubland these were 3.79tCha−1, 0.21y−1, and 0.0041y−1, correspondingly. The model sensitivity analysis revealed that for both sites, predicted soil organic carbon content was most sensitive to the total plant litter input and the RPM rate. The Iowa soil was projected to sequester 17.5tCha−1 and the Greek soil 54tCha−1 over 100 years and the projected uncertainty was 65.6% and 70.8%, respectively. We propose this methodology to assess the factors affecting carbon sequestration in agricultural soils and quantify the uncertainties.

Agricultural Soil Carbon Sequestration Offset Programs: Strengths, Difficulties, and Suggestions for Their Potential Use in AB 32's Cap and Trade Program

Agricultural Soil Carbon Sequestration Offset Programs: Strengths, Difficulties, and Suggestions for Their Potential Use in AB 32's Cap and Trade Program

Strategies for carbon sequestration in agricultural soils in northern Europe

We present new and synthesize published results from long-term field studies exploring management options for carbon sequestration in cropland and grassland. Agricultural practices were evaluated within the framework set by global food demand and limited area available for agricultural production. Among options for higher C sequestration, we found minimizing the time with bare soil, improving recycling of organic materials and increasing yields through N fertilization to be efficient. Indeed, our results suggest that C stocks can increase with 1–2 kg C for each kg of mineral N fertilizer applied. Possibilities to decrease C emissions by reduced tillage were found to be limited under Nordic conditions. Options for reducing C emissions from drained cultivated organic soils are limited when used as cropland. Extensive production leads to lower soil C stocks and requires more land. Increasing photosynthesis at the global scale by intensification of crop production was found to be the most effective mitigation option and is a prerequisite for preventing further areal expansion of agriculture.

Evaluating the demand for carbon sequestration in olive grove soils as a strategy toward mitigating climate change

In this paper we present an estimate of the economic value of carbon sequestration in olive grove soils derived from the implementation of different agricultural management systems. Carbon sequestration is considered jointly with other environmental co-benefits, such as enhanced erosion prevention and increased biodiversity. The estimates have been obtained using choice experiments and show that there is a significant demand from society for these environmental services. From a policy perspective, an agri-environmental scheme that delivers the highest level of each environmental service would be valued by society at 121 Euros per hectare. If we focus on carbon sequestration, each ton of CO2 would be valued at 17 Euros. These results show that there is scope to include agricultural soil carbon sequestration in climate change mitigation strategies and to provide guidance for setting payments for agri-environmental schemes promoting soil management changes.

Compost Changed Soil Organic Matter Molecular Composition: A Py-GC/MS and Py-FIMS Study

Changes in the molecular composition of soil organic matter (SOM) resulting from compost application are not sufficiently known at the molecular scale even though this is a major issue for soil fertility and soil carbon sequestration. Therefore, the present study investigated effects of long-term compost application in comparison to mineral fertilizer on the molecular composition of SOM in a 34-year-old experiment. Soil samples were taken after 19 and 34 years of constant management and analyzed by Curie point Pyrolysis-Gas Chromatography/Mass Spectrometry (Cp Py-GC/MS) and Pyrolysis-Field Ionization Mass Spectrometry (Py-FIMS). In general, compost application increased the organic carbon (C) content. The Cp PyGC/MS revealed larger relative intensities of alkylphenols/lignin monomers at the expense of carbohydrates in the compost treatments. Py-FIMS indicated higher proportions of labile n-fatty acids, lipids and sterols in the compost than in the mineral fertilizer treatment. Permanent cropping of grass between years 19 and 34 revealed similar signal patterns, which is also maintained after conversion of soil from permanent grass to arable use. Thermograms of volatilization indicated enrichments of stable (compounds volatilized in between 370°C and 570°C) phenols/lignin monomers, lipids and alkylaromatics between years 19 and 34 in compost fertilized soils. This was a result of enhanced losses of compounds that are considered easily metabolized by microorganisms (e.g. carbohydrates) after compost addition as derived from Py-GC/MS and Py-FIMS. In summary, long-term application of mature compost was shown to have a positive, long lasting effect on the organic carbon sequestration in agricultural soils.

Carbon Sequestration in Agricultural Soils: a Multidisciplinary Approach to Innovative Methods ‐ by Piccolo A.

European Journal of Soil ScienceVolume 63, Issue 4 p. 536-536 Carbon Sequestration in Agricultural Soils: a Multidisciplinary Approach to Innovative Methods - by Piccolo A. Jens Leifeld, Jens LeifeldSearch for more papers by this author Jens Leifeld, Jens LeifeldSearch for more papers by this author First published: 14 August 2012 https://doi.org/10.1111/j.1365-2389.2012.01477.xRead the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume63, Issue4August 2012Pages 536-536 RelatedInformation

Assessing costs of soil carbon sequestration by crop-livestock farmers in Western Australia

Carbon sequestration in agricultural soil has been identified as a potential strategy to offset greenhouse gas emissions. Within the public debate, it has been claimed that provision of positive incentives for farmers to change their land management will result in substantial carbon sequestration in agricultural soils at a low carbon price. However, there is little information about the costs or benefits of carbon sequestration in agricultural soils to test these claims. In this study, the costeffectiveness of alternative land-use and land-management practices that can increase soil carbon sequestration is analysed by integrating biophysical modelling of carbon sequestration with wholefarm economic modelling. Results suggest that, for a case study model of a crop-livestock farm in the Western Australian wheatbelt, sequestering higher levels of soil carbon by changing rotations (to include longer pasture phases) incur considerable opportunity costs. Under current commodity prices, farmers would forego more than $80 in profit for every additional tonne of CO2-e stored in soil, depending on their adoption of crop residue retention practices. This is much higher than the initial carbon price of $23t−1 in Australia’s recently legislated carbon tax. This analysis does not incorporate the possibility that greenhouse gas emissions may increase as a result of including longer pasture phases. Accounting for emissions may substantially reduce the potential for net carbon sequestration at low carbon prices.

Characterization of Humic Carbon in Soil Aggregates in a Long‐term Experiment with Manure and Mineral Fertilization

Carbon stabilization in soil aggregates has been proposed as an important mechanism for carbon sequestration in agricultural soils. However, few studies have investigated how long‐term strategies for accumulating C in the soil (e.g., organic fertilizers) can affect humic substance composition in aggregate‐size fractions. The aim of this work was to investigate the effects of long‐term application of farmyard manure (FYM) and mineral (MIN) fertilization on the humic carbon (HC) chemical structure extracted from macroaggregates (MA) (2000–250μm), microaggregates (MI) (53–250 μm) and silt–clay (SC) (&lt;53 μm) fractions of two different soils (clay and peaty) by using δ13C, solid‐state 13C cross‐polarization‐magic angle spinning nuclear magnetic resonance (CP MAS 13C NMR) and diffuse reflectance infrared Fourier transform (DRIFT) analyses. Results showed that FYM had improved the HC concentration compared with the unfertilized and MIN fertilization. In clay soil, MIN fertilization led to a significantly heavier isotope 13C enrichment in the SC than macro‐ and microaggregate fractions, suggesting that HC in this fraction was the oldest and most stabilized. This was not so evident in peaty soil, where the HC was probably in an early stage of the humification process. In addition, the HC structure changed in both soils as a consequence of the treatments. The FYM amendment caused a decrease in O, N‐alkyl‐C, and alkyl C from macroaggregate to SC fractions, suggesting an advanced state of humic component degradation. However, FYM led to a considerably positive effect on the aromatic C content in both soils. This effect was magnified in the microaggregates of clay soil. These results revealed that the structural changes of HC in different soil aggregates make it possible to understand the effects of mineral and organic fertilization on cultivated soils.

Trends in primary particulate matter emissions from Canadian agriculture

Particulate matter (PM) has long been recognized as an air pollutant due to its adverse health and environmental impacts. As emission of PM from agricultural operations is an emerging air quality issue, the Agricultural Particulate Matter Emissions Indicator (APMEI) has been developed to estimate the primary PM contribution to the atmosphere from agricultural operations on Census years and to assess the impact of practices adopted to mitigate these emissions at the soil landscape polygon scale as part of the agri-environmental indicator report series produced by Agriculture and Agri-Food Canada. In the APMEI, PM emissions from animal feeding operations, wind erosion, land preparation, crop harvest, fertilizer and chemical application, grain handling, and pollen were calculated and compared for the Census years of 1981–2006. In this study, we present the results for PM10 and PM2.5, which exclude chemical application and pollen sources as they only contribute to total suspended particles. In 2006, PM emissions from agricultural operations were estimated to be 652.6 kt for PM10 and 158.1 kt for PM2.5. PM emissions from wind erosion and land preparation account for most of PM emissions from agricultural operations in Canada, contributing 82% of PM10 and 76% of PM2.5 in 2006. Results from the APMEI show a strong reduction in PM emissions from agricultural operations between 1981 and 2006, with a decrease of 40% (442.8 kt) for PM10 and 47% (137.7 kt) for PM2.5. This emission reduction is mainly attributed to the adoption of conservation tillage and no-till practices and the reduction in the area of summerfallow land. Implications: Increasing sustainability in agriculture often means adapting management practices to have a beneficial impact on the environment while maintaining or increasing production and economic benefits. We developed an inventory of primary PM emissions from agriculture in Canada to better quantify the apportionment, spatial distribution, and trends for Census years 1981–2006. We found major reductions of 40% in PM10 and 47% in PM2.5 emissions over the 25-yr period as a co-benefit of increasing carbon sequestration in agricultural soils. Indeed, farmers adopted conservation tillage/no-till practices, increased usage of cover crops, and reduced summerfallow, in order to increase soil organic matter and reduce carbon dioxide emissions, which also reduced primary PM emissions, although the agricultural production increased over the period. Supplemental Materials: Supplemental materials are available for this article. Go to the publisher's online edition of the Journal of the Air & Waste Management Association for primary PM emissions at the soil landscape polygon scale from Canadian agricultural sources in 2006 (adapted from Pattey et al., 2010) and for previous Census years between 1981 and 2001.

Soil organic carbon storage in a no-tillage chronosequence under Mediterranean conditions

The duration of soil organic carbon (SOC) sequestration in agricultural soils varies according to soil management, land-use history and soil and climate conditions. Despite several experiments have reported SOC sequestration with the adoption of no-tillage (NT) in Mediterranean dryland agroecosystems scarce information exists about the duration and magnitude of the sequestration process. For this reason, 20 years ago we established in northeast Spain a NT chronosequence experiment to evaluate SOC sequestration duration under Mediterranean dryland conditions. In July 2010 we sampled five chronosequence phases with different years under NT (i.e., 1, 4, 11, and 20 years) and a continuous conventional tillage (CT) field, in which management prevailed unchanged during decades. Soil samples were taken at four depths: 0–5, 5–10, 10–20 and 20–30 cm. The SOC stocks were calculated from the SOC concentration and soil bulk density. Furthermore, we applied the Century ecosystem model to the different stages of the chronosequence to better understand the factors controlling SOC sequestration with NT adoption. Differences in SOC stocks were only found in the upper 5 cm soil layer in which 4, 11 and 20 years under NT showed greater SOC stocks compared with 1 year under NT and the CT phase. Despite no significant differences were found in the total SOC stock (0–30 cm soil layer) there was a noteworthy difference of 5.7 Mg ha−1 between the phase with the longest NT duration and the phase under conventional tillage. The maximum annual SOC sequestration occurred after 5 years of NT adoption with almost 50% change in the annual rate of SOC sequestration. NT sequestered SOC over the 20 years following the change in management. However, more than 75% of the total SOC sequestered was gained during the first 11 years after NT adoption. The Century model predicted reasonably well SOC stocks over the NT chronosequence. In Mediterranean agroecosystems, despite the continuous use of NT has limited capacity for SOC sequestration, other environmental and agronomic benefits associated to this technique may justify the maintenance of NT over the long-term.

Some Unaddressed Issues in Proposed Cap‐and‐Trade Legislation Involving Agricultural Soil Carbon Sequestration

Some Unaddressed Issues in Proposed Cap‐and‐Trade Legislation Involving Agricultural Soil Carbon Sequestration

Biochar as a strategy to sequester carbon and increase yield in durum wheat

Carbon sequestration in agricultural soils is a climate change mitigation option since most of cultivated soils are depleted of soil organic carbon and far from saturation. The management practices, most frequently suggested to increase soil organic carbon content have variable effects depending on pedo-climatic conditions and have to be applied for a long time periods to maintain their sink capacity. Biochar (BC), a carbon rich product obtained through carbonization of biomass, can be used for carbon sequestration by applying large amounts of carbon very resistant to decomposition. The BC remains into soil for a long time and there is evidence that the BC stores atmospheric carbon from centennial, to millennial timescales. However most of the agronomic studies on BC application have been made in tropical and sub-tropical climates, while there is a substantial lack of studies at mid-latitudes and in temperate climates. This paper presents the results on an investigation of large volume application of BC (30 and 60 t ha −1) on durum wheat in the Mediterranean climate condition, showing the viability of BC application for carbon sequestration on this crop. BC application also has positive effects up to 30% on biomass production and yield, with no differences in grain nitrogen content. Moreover no significant differences between the two BC treatments were detected, suggesting that even very high BC application rates promote plant growth and are, certainly, not detrimental. The effect of the biochar on durum wheat was sustained for two consecutive seasons when BC application was not repeated in the second year.

Can no-tillage stimulate carbon sequestration in agricultural soils? A meta-analysis of paired experiments

Adopting no-tillage in agro-ecosystems has been widely recommended as a means of enhancing carbon (C) sequestration in soils. However, study results are inconsistent and varying from significant increase to significant decrease. It is unclear whether this variability is caused by environmental, or management factors or by sampling errors and analysis methodology. Using meta-analysis, we assessed the response of soil organic carbon (SOC) to conversion of management practice from conventional tillage (CT) to no-tillage (NT) based on global data from 69 paired-experiments, where soil sampling extended deeper than 40 cm. We found that cultivation of natural soils for more than 5 years, on average, resulted in soil C loss of more than 20 t ha −1, with no significant difference between CT and NT. Conversion from CT to NT changed distribution of C in the soil profile significantly, but did not increase the total SOC except in double cropping systems. After adopting NT, soil C increased by 3.15 ± 2.42 t ha −1 (mean ± 95% confidence interval) in the surface 10 cm of soil, but declined by 3.30 ± 1.61 t ha −1 in the 20–40 cm soil layer. Overall, adopting NT did not enhance soil total C stock down to 40 cm. Increased number of crop species in rotation resulted in less C accumulation in the surface soil and greater C loss in deeper layer. Increased crop frequency seemed to have the opposite effect and significantly increased soil C by 11% in the 0–60 cm soil. Neither mean annual temperature and mean annual rainfall nor nitrogen fertilization and duration of adopting NT affected the response of soil C stock to the adoption of NT. Our results highlight that the role of adopting NT in sequestrating C is greatly regulated by cropping systems. Increasing cropping frequency might be a more efficient strategy to sequester C in agro-ecosystems. More information on the effects of increasing crop species and frequency on soil C input and decomposition processes is needed to further our understanding on the potential ability of C sequestration in agricultural soils.

Carbon accumulation in soil. Ten-year study of conservation tillage and crop rotation in a semi-arid area of Castile-Leon, Spain

Abstract Minimum (MT) or no tillage (NT) and increased cropping intensity can enhance soil structure and raise carbon sequestration in agricultural soils. The effectiveness of these procedures depends on soil type, crops, and tillage management systems. Increases in the organic carbon content may be affected by crop type, crop rotation and the quality and quantity of crop residues left on the soil surface. Soil organic carbon (SOC) is a good indicator of soil quality and conservation. The present study was conducted from 1994 to 2004 at Torrepadierne, Burgos, a cereal farming area in Spain, on Typic Calcixerolls soil with a 1.8% soil organic matter (SOM) content. The average annual rainfall in the area is 448 mm. A split-plot experimental design was used, in which the main factor was the tillage system – conventional (CT), minimum (MT) or no-till (NT) – and the sub-factor crop rotation – cereal/cereal (C–C), cereal/fallow (C–F) and cereal/legume (C–L). Fallow/cereal and legume/cereal were added to these sequences to have the same crops every year. The present study was conducted to determine the effect of tillage systems and cropping sequences on SOC patterns after 10 years of soil management. At a depth of 0–10 cm, the SOC content was significantly higher with NT than CT or MT, by 58% and 11%, respectively. SOC values were 41% higher with MT, in turn, than with CT. At a depth of 10–20 cm, the SOC content was 30% higher with NT than with CT and 7% higher than with MT. And at 20–30 cm, it was 7% higher with MT than with CT, 12% higher with NT than CT and 9% higher with no-till than minimum-till. In 2004, at the end of the 10 years period, SOC was 25% greater with NT than CT, 16% greater with NT than MT, and 17% higher with MT than CT. Crop rotation was not observed to have any significant effect on the SOC content in 2004, however. These findings suggest that carbon sequestration in the 30 cm layer can be improved if NT or MT are used in lieu of conventional practice. The total crop residue returning to the soil was significantly greater in plots sown with legume after cereal harvest than in plots left fallow. It also enhanced SOC sequestration in non- or minimally tilled soils.

On fertilizer‐induced soil carbon sequestration in China's croplands

AbstractApplications of fertilizer, often thought to enhance carbon sequestration in agricultural soils, are of no value to the mitigation of climate change if the carbon dioxide released during the production and distribution of nitrogen fertilizer exceeds the incremental carbon storage in soils from its use. Nitrogen fertilizer is also a source of the greenhouse gas nitrous oxide. The recent analysis of carbon sequestration in cropland soils of China does not apply these ‘discounts’ to the global warming mitigation expected from greater use of fertilizer; doing so would likely eliminate all the climate benefits of the postulated enhanced carbon sequestration.

Tillage and cropping effects on soil organic carbon in Mediterranean semiarid agroecosystems: Testing the Century model

Carbon sequestration in agricultural soils can contribute to offsetting CO 2 anthropogenic emissions and also to enhance soil fertility, soil water retention and crop production. In this experiment, our main objective was to validate the Century model for Mediterranean semiarid agroecosystems and to investigate management effects on soil organic carbon (SOC) dynamics in these areas. Data from a long-term experiment in NE Spain comparing three tillage systems (no-tillage, NT; reduced tillage, RT; conventional tillage, CT) and two cropping systems (barley-fallow rotation, BF and continuous barley system, CB) was used to simulate SOC with the Century model in the 0–30 cm soil depth. The model was able to accurately simulate SOC and above-ground C inputs under different tillage systems although it over-estimated C inputs in some growing seasons (e.g. 2000). Simulated and measured C inputs showed a significant relationship ( P < 0.001; R 2 = 0.83) and both tended to decrease as tillage intensity decreases but differences were not statistically significant. However, SOC content was greater under NT than under CT and RT. Also, intensification of cropping systems (i.e. eliminating bare fallow) led to greater SOC in all tillage treatments. Consequently, SOC sequestration rates were greatest in NT followed by RT and CT in the CB system with 0.46, 0.24 and 0.18 Mg C ha −1 yr −1, respectively. In the BF rotation lower SOC sequestration rates were found with values ranged from 0.15 to −0.004 Mg C ha −1 yr −1 in NT and CT, respectively. Both simulation and measured values showed that reduction in tillage intensity and an intensification of the cropping system are promising strategies to increase SOC sequestration under semiarid Mediterranean conditions. The Century model is a useful tool to simulate tillage and cropping system effects on SOC dynamics in semiarid Mediterranean agroecosystems.

Dissolved organic carbon in streams from artificially drained and intensively farmed watersheds in Indiana, USA

Dissolved organic carbon (DOC) in streams draining hydrologically modified and intensively farmed watersheds has not been well examined, despite the importance of these watersheds to water quality issues and the potential of agricultural soils to sequester carbon. We investigated the dynamics of DOC for 14 months during 2006 and 2007 in 6 headwater streams in a heavily agricultural and tile-drained landscape in the midwestern US. We also monitored total dissolved nitrogen (TDN) in the streams and tile drains. The concentrations of DOC in the streams and tile drains ranged from approximately 1–6 mg L−1, while concentrations of TDN, the composition of which averaged >94% nitrate, ranged from 10 mg L−1. Tile drains transported both DOC and TDN to the streams, but tile inputs of dissolved N were diluted by stream water, whereas DOC concentrations were generally greater in the streams than in tile drains. Filamentous algae were dense during summer base flow periods, but did not appear to contribute to the bulk DOC pool in the streams, based on diel monitoring. Short-term laboratory assays indicated that DOC in the streams was of low bioavailability, although DOC from tile drains in summer had bioavailability of 27%. We suggest that these nutrient-rich agricultural streams are well-suited for examining how increased inputs of DOC, a potential result of carbon sequestration in agricultural soils, could influence ecosystem processes.