Keith Paustian

Colorado State University | CSU · Natural Resource Ecology Laboratory

Anthropogenic activities have altered approximately two‐thirds of the Earth's land surface. Urbanization, industrialization, agricultural expansion, and deforestation are increasingly impacting the terrestrial landscapes, leading to shifts of areas in artificial surface (i.e., humanmade), cropland, pasture, forest, and barren land. Land use pattern...

Grazing lands play a significant role in global carbon (C) dynamics, holding substantial soil organic carbon (SOC) stocks. However, historical mismanagement (e.g., overgrazing and land-use change) has led to substantial SOC losses. Regenerative practices, such as adaptive multi-paddock (AMP) grazing, offer a promising avenue to improve soil health...

Climate-smart agriculture can be used to build soil carbon stocks, decrease agricultural greenhouse gas (GHG) emissions, and increase agronomic resilience to climate pressures. The US recently declared its commitment to include the agricultural sector as part of an overall climate-mitigation strategy, and with this comes the need for robust, scient...

As food companies have adopted sustainability metrics to quantify the environmental impacts of supply chains, we need data-driven decision support tools that represent organic management practices. Decision support tools such as COMET-Farm and the Cool Farm Tool have been developed to estimate management practice impacts on soil carbon and greenhou...

[Open access article 10.1111/gcb.17233] Nitrous oxide (N 2 O) exacerbates the greenhouse effect and thus global warming. Agricultural management practices, especially the use of nitrogen (N) fertilizers and irrigation, increase soil N 2 O emissions. As a vital sector of global agriculture, specialty crop systems usually require intensive input and...

Improved agricultural soil management can facilitate the removal of carbon dioxide from the atmosphere to help keep planetary warming at or below 2 °C as outlined in the Paris Agreement. The application of compost to agricultural soils increases soil carbon by directly fertilizing the soil with carbon (no net carbon dioxide removal), and by stimula...

Meeting end-of-century global warming targets requires aggressive action on multiple fronts. Recent reports note the futility of addressing mitigation goals without fully engaging the agricultural sector, yet no available assessments combine both nature-based solutions (reforestation, grassland and wetland protection, and agricultural practice chan...

Increasing demand for land-based climate mitigation requires more efficient management of agricultural landscapes for competing objectives. Here we develop methods for assessing trade-offs and synergies between intensification and carbon-sequestering conservation measures in annual crop production landscapes using the DayCent ecosystem model and th...

Sustainable aviation fuel (SAF) production from lipids is a technologically mature approach for replacing conventional fossil fuel use in the aviation sector, and there is increasing demand for such feedstocks. The oilseed Brassica carinata (known as Ethiopian mustard or simply carinata) is a promising SAF feedstock that can be grown as a supplemen...

Considering the importance of soil organic carbon (SOC) and the scarcity of data on how soil management influences its storage in the region, this study assessed the long-term impact of different soil management systems on SOC in southern Ethiopia using the DAYCENT model. The conservation management systems considered were minimum tillage, crop res...

CONTEXT Cover crops deliver numerous ecosystem services including the capacity to sequester and store atmospheric CO2 offering promise as a natural climate solution. Farm system models must be able to accurately represent cover crop systems and estimate the associated net greenhouse gas emissions from this practice across agricultural contexts. OB...

For decades, predominant soil biogeochemical models have used conceptual soil organic matter (SOM) pools and only simulated them to a shallow depth in soil. Efforts to overcome these limitations have prompted the development of the new generation SOM models, including MEMS 1.0, which represents measurable biophysical SOM fractions, over the entire...

The Systems Ecology Paradigm (SEP) incorporates humans as integral parts of ecosystems and emphasizes issues that have significant societal relevance such as grazing land, forestland, and agricultural ecosystem management, biodiversity and global change impacts. Accomplishing this societally relevant research requires cutting-edge basic and applied...

The Systems Ecology Paradigm (SEP) incorporates humans as integral parts of ecosystems and emphasizes issues that have significant societal relevance such as grazing land, forestland, and agricultural ecosystem management, biodiversity and global change impacts. Accomplishing this societally relevant research requires cutting-edge basic and applied...

The Systems Ecology Paradigm (SEP) incorporates humans as integral parts of ecosystems and emphasizes issues that have significant societal relevance such as grazing land, forestland, and agricultural ecosystem management, biodiversity and global change impacts. Accomplishing this societally relevant research requires cutting-edge basic and applied...

Nitrogen (N) loss through ammonia \(({\mathrm{NH}}_{3})\) volatilization in agricultural soils is a significant source of atmospheric \({\mathrm{NH}}_{3}\), contributing to low N use efficiency in crops, risk to human health, environmental pollution, and is an indirect source of nitrous oxide \(({\mathrm{N}}_{2}\mathrm{O})\) emissions. Our objectiv...

Globally, poorly managed pasture can contribute to increasing greenhouse gas (GHG) emissions. In Brazil, sustainable management systems are being proposed to reduce carbon dioxide (CO 2) emissions and increase the soil C stock under degraded pasture. However, despite the potential benefits in the adoption of sustainable management systems, few stud...

For decades, predominant soil biogeochemical models have used conceptual soil organic matter (SOM) pools and only simulated them to a shallow depth in soil. Efforts to overcome these limitations have prompted the development of new generation SOM models, including MEMS 1.0, which represents measurable biophysical SOM fractions, over the entire root...

The Forest Vegetation Simulator (FVS) growth and yield model is widely used throughout the United States, but recent studies have reported unexpectedly large bias for some regional model variants. Here we propose a general framework for model evaluation, designed to highlight model strengths and weaknesses and inform calibration efforts. We apply t...

Sustainable soil carbon sequestration practices need to be rapidly scaled up and implemented to contribute to climate change mitigation. We highlight that the major potential for carbon sequestration is in cropland soils, especially those with large yield gaps and/or large historic soil organic carbon losses. The implementation of soil carbon seque...

Significance The climate benefits of cellulosic biofuels have been challenged based on carbon debt, opportunity costs, and indirect land use change, prompting calls for withdrawing support for research and development. Using a quantitative ecosystem modeling approach, which explicitly differentiates primary production, ecosystem carbon balance, and...

Increasing the amount of soil organic carbon (SOC) has agronomic benefits and the potential to mitigate climate change. Previous regional predictions of SOC trends under climate change often ignore or do not explicitly consider the effect of crop adaptation (i.e., changing planting dates and varieties). We used the DayCent biogeochemical model to e...

Accurate estimation of crop net primary production (NPP) and yields is fundamental for regional analyses of agroecosystem dynamics using process‐based models. In this study, we simulated croplands in the contiguous U.S. using the DayCent ecosystem model with new production algorithms. Crops were divided into crop variety groups based on regional va...

Crop water production functions (quantifying crop yield as a function of irrigation rate) can help in the design of management systems that reduce the water footprint. We examined the role of parameter uncertainties in characterizing production functions using the DayCent agroecosystem model. A global sensitivity analysis was conducted to identify...

During the last decade, China's agro-food production has increased rapidly and been accompanied by the challenge of increasing greenhouse gas (GHG) emissions and other environmental pollutants from fertilizers, pesticides, and intensive energy use. Understanding the energy use and environmental impacts of crop production will help identify environm...

Carbon accounting at the nexus of forest management and bioenergy production has long been complex and controversial, particularly regarding whether woody feedstocks can be sustainably sourced without counter-productive reductions in forest ecosystem carbon storage. In the western U.S., recent bark beetle outbreaks have caused widespread tree morta...

The adoption of more intensive and diversified pasture systems is a promising alternative to improve sustainability of grazing lands in Brazil. Phosphorus (P) is one of the main determinants of ecosystem function in these management systems; therefore, we assessed the effects of adopting more intensive and diversified pasture management systems on...

Soil carbon (C) sequestration is one of three main approaches to carbon dioxide removal and storage through management of terrestrial ecosystems. Soil C sequestration relies of the adoption of improved management practices that increase the amount of carbon stored as soil organic matter, primarily in cropland and grazing lands. These C sequestering...

The importance of building/maintaining soil carbon, for soil health and CO2 mitigation, is of increasing interest to a wide audience, including policymakers, NGOs and land managers. Integral to any approaches to promote carbon sequestering practices in managed soils are reliable, accurate and cost-effective means to quantify soil C stock changes an...

Early thinning of loblolly pine plantations can potentially deliver sustainable feedstocks for biofuel/bioenergy. However, the management intensification for increased productivity and the removal of additional biomass from these plantations could reduce carbon (C) inputs belowground and therefore reduce overall ecosystem C storage. Increased ferti...

Soil organic matter (SOM) dynamics in ecosystem-scale biogeochemical models have traditionally been simulated as immeasurable fluxes between conceptually defined pools. This greatly limits how empirical data can be used to improve model performance and reduce the uncertainty associated with their predictions of carbon (C) cycling. Recent advances i...

We demonstrate the use of a surrogate-based optimization framework for large-scale and high-resolution landscape management optimization, using irrigated corn production systems in eastern Colorado, USA as a case study. An artificial neural network was employed to create a surrogate of the DayCent biogeochemical simulation model. Our optimization c...

Biofuels have been proposed as a potential solution for climate change mitigation. However, there exist several barriers, such as "food vs fuel" issues and technological constraints, restricting the sustainable commercialization of both first-and second-generation biofuels. Combining arable crops and their residues for hybrid first-and second-gener...

Soil organic matter (SOM) dynamics in ecosystem-scale biogeochemical models have traditionally been simulated as immeasurable fluxes between conceptually-defined pools. This greatly limits how empirical data can be used to improve model performance and reduce the uncertainty associated with their predictions of carbon (C) cycling. Recent advances i...

A promising solution to help close the gap between water demand and supply in semiarid regions is deficit irrigation strategies that use less water but aim to increase crop yield per unit of water applied. Dynamic models can be used to assess the impacts of deficit irrigation and to support decision-making. In this study, we evaluated the capabilit...

Agricultural land management often involves trade-offs between ecosystem services (ES) and disservices (EDS). Balancing these trade-offs to achieve low-impact production of agricultural commodities requires rigorous approaches for quantifying and optimizing ES and EDS, reconciling biophysical constraints and different management objectives. In this...

Core Ideas A new version of the DayCent model was capable of simulating the responses in maize‐dominated agroecosystems under water‐deficit conditions. The accuracy of DayCent‐simulated GLAI, biomass, SWC, and yield was similar to that observed with more complex models. There was no significant difference in the major output variables when the stre...

The presence of soil organic matter (SOM) is seen as essential for soil health. Modelling SOM in soils helps researchers and farmers understand and predict the effects of different cultivation practices on changes in SOM. This chapter reviews key issues in SOM modelling and the development of increasingly sophisticated, dynamic SOM models. It looks...

Agriculture provides many ecosystem services to human society but is also a major cause of environmental degradation. The key challenge of modern agricultural production is to meet projected increases in global demands for food, water, and energy in sustainable ways. Sustainable agricultural production requires integrated decision-support tools and...

Core Ideas Green leaf weight ratio (GLWR) of annual crops can be approximated by piece‐wise linear equations over the entire growing season. Our modified green leaf area index (GLAI) method is simple yet both general and robust for simulation of GLAI of annual grain crops. Incorporation of this new approach in DayCent model yielded substantial impr...

Although dedicated energy crops will probably be an important feedstock for future cellulosic bioenergy production, it is unknown how they can best be integrated into existing agricultural systems. Here we use the DayCent ecosystem model to simulate various scenarios for growing switchgrass in the heterogeneous landscape that surrounds a commercial...

Table S1. Summary of scenarios in publications on soil N2O emissions from perennial bioenergy crops underlying Fig. 1. Table S2. Annual average (mean) N2O emissions [Mg N2O ha−1 yr−1, mean ± SE (n)] calculated for four feedstocks individually. Appendix S1. Method for calculation of net greenhouse gas (GHG) intensity for four biofuel production sc...

United States mandated the production of biofuel from lignocellulosic feedstocks. Nonetheless, the cultivation of these feedstocks may produce debates, as agricultural land is scarce and it is primarily needed for food production and grazing. Thus, it is thought that biofuel production should be placed on land with low economical value (i.e. margin...

Perennial bioenergy crops have significant potential to reduce greenhouse gas (GHG) emissions and contribute to climate change mitigation by substituting for fossil fuels; yet delivering significant GHG savings will require substantial land-use change, globally. Over the last decade, research has delivered improved understanding of the environmenta...

In rapidly urbanizing semi-arid regions, increasing amounts of historically irrigated cropland lies permanently fallowed due to water court policies as agricultural water rights are voluntarily being sold to growing cities. This study develops an integrative framework for assessing the effects of population growth and land use change on agricultura...

In Mediterranean agroecosystems, limited information exists about possible impacts of climate change on soil N2O emissions under different land uses. This paper presents a modelling study with a dual objective. Firstly, the biogeochemical Daycent model was evaluated to predict soil N2O emissions in different land uses in a typical Mediterranean agr...

The '4 per mille Soils for Food Security and Climate' was launched at the COP21 with an aspiration to increase global soil organic matter stocks by 4 per 1000 (or 0.4 %) per year as a compensation for the global emissions of greenhouse gases by anthropogenic sources. This paper surveyed the soil organic carbon (SOC) stock estimates and sequestratio...

Cassava-based ethanol has been promoted in China and Southeast Asia as an effective means to reduce greenhouse gas (GHG) emissions and promote energy security. However, existing life cycle assessments of the environmental impacts of cassava ethanol have used highly-aggregated empirical methods to estimate ecosystem C stock changes, which do not cap...

In recent years, the increase in Brazilian ethanol production has been based on expansion of sugarcane-cropped area, mainly by the land use change (LUC) pasture–sugarcane. However, second-generation (2G) cellulosic-derived ethanol supplies are likely to increase dramatically in the next years in Brazil. Both these management changes potentially aff...

Background and aims To study the impact of land use change (LUC) from native vegetation and pasture to sugarcane cultivation as well as to evaluate the effect of different management practices on long-term SOC dynamics using the CENTURY ecosystem model. Methods A soil data set of 85 study areas including sugarcane, pasture and annual crops from el...

Different residue management practices can affect carbon (C) allocation and thus soil C and nitrogen (N) turnover. A biogeochemical model, DAYCENT, was used to simulate the effects of bioenergy Sorghum [Sorghum bicolor (L.) Moench] residue return on soil temperature and water content, soil organic carbon (SOC), and greenhouse gas (GHG) [carbon diox...

Grassland ecosystems cover a large portion of the Earths' surface and contain substantial amounts of soil organic carbon. Previous work has established that these soil carbon stocks are sensitive to management and land use changes - grazing, species composition, and mineral nutrient availability can lead to losses or gains of soil carbon. Because o...

Agroforestry as a land management practice presents a method for partially offsetting greenhouse gas emissions from agricultural land. Of all agroforestry practices in the United States, windbreaks in particular are used throughout the United States providing a useful starting point for deriving a modelling system which could quantify the amount of...

New understanding of the connection between dynamic microbial carbon use efficiency (CUE), litter decomposition products, and pathways of soil organic carbon (SOC) formation have not been fully integrated into current generalizable litter decomposition models. We developed a new approach, the Litter Decomposition and Leaching (LIDEL) model, that: 1...

Cattle play a major role in nutrient cycling of grassland ecosystems through biomass removal and excrement deposition (urine and feces). We studied the effects of cattle excrement patches (urine at 430 and feces at 940 kg N ha-1) on nitrous oxide (N2O) and methane (CH4) fluxes using semi-static chambers on cool-season (C3), Bozoisky-select (Psathyr...

In 2014, the USAID project ‘Grazing lands, livestock and climate resilient mitigation in Sub-Saharan Africa’ held two workshops, hosted by the Colorado State University, which brought together experts from around the world. Two reports resulted from these workshops, one an assessment of the state of the science, and the other an inventory of relate...

Soils are the third largest global reservoir of carbon and the largest terrestrial ecosystem sink or source of atmospheric CO2 depending on land-use and management. The French authorities ahead of COP21 proposed the ‘four per mil’ initiative aimed at offsetting most global agricultural CO2 emissions by increasing global soil organic carbon (SOC). S...

More than 13 Mha of nonfederal land in the southeastern U.S. are devoted to pastureland. Between 1982 and 1992, pastureland increased by 100,000 ha, with nearly 70% converted from cultivated land. We examined the potential for carbon (C) sequestration with improved pasture management and conversion into pastureland from cultivated land. Improved pa...

Soils are integral to the function of all terrestrial ecosystems and to food and fibre production. An overlooked aspect of soils is their potential to mitigate greenhouse gas emissions. Although proven practices exist, the implementation of soil-based greenhouse gas mitigation activities are at an early stage and accurately quantifying emissions an...

Soils are subject to varying degrees of direct or indirect human disturbance, constituting a major global change driver. Factoring out natural from direct and indirect human influence is not always straightforward, but some human activities have clear impacts. These include land use change, land management, and land degradation (erosion, compaction...

Under the international protocols aiming at reducing the climate change impact, the land use sector is, likely, one of most complex to be accounted for greenhouse gas (GHG) emission and removal. This is related to its fragmentation and the complex biogeochemical feedbacks interacting with the human activity. Among those feedbacks, the role of erosi...

The idea of offsetting anthropogenic CO2 emissions by increasing global soil organic carbon (SOC), as recently proposed by French authorities ahead of COP21 in the 'four per mil' initiative, is notable. However, a high uncertainty still exits on land C balance components. In particular, the role of erosion in the global C cycle is not totally disen...

Soils play a pivotal role in major global biogeochemical cycles (carbon, nutrient and water), while hosting the largest diversity of organisms on land. Because of this, soils deliver fundamental ecosystem services, and management to change a soil process in support of one ecosystem service can either provide co-benefits to other services or can res...