ASSESSMENT OF THE CARBON SEQUESTRATION POTENTIAL OF COMMON AGRICULTURAL SYSTEMS ON BENCHMARK SOILS ACROSS THE SOUTHERN REGION CLIMATE GRADIENT

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: TERMINATED
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 1000149
• Project No.: FLA-ONA-005258
• Multistate No.: S-1048
• Project Start Date: Jul 24, 2013
• Project End Date: Sep 30, 2016

Project Director
Silveira, M.

Recipient Organization
UNIVERSITY OF FLORIDA
G022 MCCARTY HALL
GAINESVILLE,FL 32611

Performing Department
Range Cattle Research and Education Center, Ona

Non Technical Summary
Grazing lands can be important sinks of atmospheric CO2 and play a major role in the overall carbon cycle fluxes. Unlike tropical forests, where the majority of the carbon is stored in the vegetation, as much as 90% of the carbon pools in grazing-land ecosystems are located in the soil, hence, it can be readily transferred into more permanent storage in the soil. Because carbon stored below ground is more permanent than plant biomass, soil carbon sequestration in grazing lands provides a long-term alternative to mitigate atmospheric greenhouse gas emissions. Because native and improved pasturelands encompass an extensive area in the United States (~1/3 of the land area), small changes in the amount of carbon sequestered in grazing-land soils have significant consequences in the global carbon cycle. Carbon sequestration rates vary by climate, topography, soil type, management history, and current practices. The majority of the grazing lands in the United States are located in arid and semiarid ecosystems; however, grazing lands in eastern regions receive more precipitation and, consequently, have greater potential to respond to management inputs. For example, because of the warm climate and ability to grow crops year-round in Florida, there is the potential to return great amounts of carbon to the soil as above-ground (i.e., dead leaves) and below-ground (i.e., roots, root exudates) plant inputs. However, carbon accumulation in Florida's soils remains a major challenge because of the fast decomposition rates in warm and moist conditions. The main goal of this project if to identify appropriate management practices that favor carbon inputs and minimize decomposition are the key to increase carbon sequestration in Florida soils.

Animal Health Component

0%

Research Effort Categories

Basic

30%

Applied

70%

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
102	0110	1070	100%

Knowledge Area
102 - Soil, Plant, Water, Nutrient Relationships;

Subject Of Investigation
0110 - Soil;

Field Of Science
1070 - Ecology;

Keywords

soil carbon sequestration

greenhouse gas

grasslands

Goals / Objectives
The soil C sequestration potential of common cropping systems and land uses, including bio-fuel crops, on benchmark soils throughout the southern US are largely unknown. Similarly, the impact of climate regime, which can have a varying effect across the southern states, on soil C sequestration potential is largely unknown. Therefore, to address these present knowledge gaps and unify present research activities in the southern and south-eastern US into a common goal, the overall objective of this regional research project is to assess the soil carbon sequestration potential of common agricultural and natural ecosystems of varying ages on benchmark soils across the southern region climate gradient. Though the main study objective will be on direct assessment of soil carbon sequestration potential, several related sub-objectives will also be explored, namely i) evaluate the effects of land use, crop rotation, tillage practice, soil texture, and ecosystem age/rotation duration on soil carbon concentration, content, and sequestration and related soil physical and chemical properties, ii) quantify and understand the physical and chemical processes that relate to and control soil carbon sequestration, and iii) investigate spatial variability issues associated with soil carbon content and sequestration.

Project Methods
This project will be conducted in central-south Florida and will consist of different grassland biomes. Site characterization (vegetation composition, biomass, etc) will be characterized. Measurements will include gas emissions and soil C responses to grassland management. Data will be analyzed using the PROC MIXED procedure of SAS. Mean separation will be performed using the SAS least square means test (PDIFF) at P ≤ 0.05. Weather data, including rainfall and air temperature, will be constantly monitored throughout the 5-yr project.

Progress 07/24/13 to 09/30/16

Outputs
Target Audience:This project provided opportunities for students and visiting scientists to learn about the characteristics of soil carbon sequestration in the context of intensive grassland management systems. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?This project provided an unique opportunity for undergrad and graduate students as well as visiting professors to learn about the characteristics of soil C in the context of intensive grassland management systems How have the results been disseminated to communities of interest?Research data have been presented in scientific meetings as well as educational activities target farmers and youth. What do you plan to do during the next reporting period to accomplish the goals?We will continue our efforts in this area and expand our experimental sites to other locations

Impacts
What was accomplished under these goals? A variety of management practices have been suggested to increase soil C sequestration potential. These include fertilization, grazing management, irrigation, and use of highly productive forage grass and legume species. Because improved management practices are normally beneficial to forage and livestock production, they may also provide an incentive for producers to adopt strategies that enhance soil C pools. In addition, C trading-related markets and the growing interest in C sequestration as mechanisms for environmental protection are also expected to enhance the economic value of the ecological services provided by grasslands. During this current report period, we start collecting data to determine the long-term impacts of land use conversion from native rangelands into improved pastures on the amounts and characteristics of soil C stocks across different regions and through different forms of grassland management. Our central hypothesis was that management practices intended to increase biomass production and land use intensification, such as converting rangelands into improved pasture systems and introduction of grazing livestock, control organic matter production, distribution and quality and, therefore, have major effects on C sequestration.

Publications

• Type: Journal Articles Status: Accepted Year Published: 2013 Citation: Silveira, M.L., Liu, K., Sollenberger, L.E., Follett, R.F., and Vendramini, J.M.B. 2013. Short-term effects of grazing intensity and nitrogen fertilization on soil organic carbon pools under perennial grass pastures in the Southeastern USA. Soil Biol. Biochem. 58:42-49.
• Type: Journal Articles Status: Submitted Year Published: 2014 Citation: Silveira, M.L., Xu, S., Adewopo, J., Buonadio, G.A., Franzluebbers, A.J. 2013. Grazing land intensification effect on C dynamics in aggregate size fractions. Geoderma(Under review)

Progress 10/01/15 to 09/30/16

Outputs
Target Audience:Scientific community, undergraduate and graduate students, farmers, regulatory agencies Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?This project provided opportunities for students and visiting scientists to learn about the caracteristics of soil carbon sequestration in the context of intensive grassland management systems. How have the results been disseminated to communities of interest?Research data have been published in peer-reviewed journals and presented in scientific meetings and at farmers and youth meetings. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Grazing lands worldwide are increasingly subjected to intensification to meet global demand for food; however, management practices intended to increase production can also affect ecosystem carbon (C) stocks. This study evaluated long-term (> 22 yr) ecosystem C responses to conversion of native grazing lands into more intensively managed silvopasture and sown pastures.Silvopasture exhibited the greatest total ecosystem C stock (168 Mg ha-1) compared with sown pasture and native rangeland (121 and 94 Mg ha-1, respectively). This response was due to the greater aboveground biomass (59 Mg ha-1 in silvopasture vs. 2.1 and 3.8 Mg ha-1 in sown pasture and native rangeland, respectively), primarily from the tree component. Soil organic C (SOC) accounted for 81 and 90% of total ecosystem C stocks in native rangeland and sown pasture, respectively, while in silvopasture SOC represented ~ 61% of total ecosystem C. Soil organic C increased from 76 Mg ha-1 in native rangeland to 110 Mg ha-1 sown pasture. Data indicated that grazing land intensification through the adoption of proper management promoted ecosystem C primarily due to increases in SOC and the associated benefit of a greater above-ground woody biomass.

Publications

• Type: Journal Articles Status: Published Year Published: 2016 Citation: Xu, S., Silveira, M.L., Inglett, K.S., Sollenberger, L.E., Gerber, S. 2016. Effects of land-use conversion on ecosystem C stock and distribution in subtropical grazinglands. Plant and Soil, 399:233-245

Progress 10/01/14 to 09/30/15

Outputs
Target Audience:Our target audience includes undergraduate and graduate students, the scientific community, and farmers Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?This project provided opportunities for students and visiting scientists to learn about the caracteristics of soil carbon sequestration in the context of intensive grassland management systems. How have the results been disseminated to communities of interest?Research data have beenpublished inpeer-reviewed journals and presented in scientific meetings and at farmers and youthmeetings. What do you plan to do during the next reporting period to accomplish the goals?We will continue our efforts in this area by collecting and analyzing additionalsoil, plant tissue, and gas samples.

Impacts
What was accomplished under these goals? Grazing lands worldwide are increasingly subjected to intensification to meet global demand for food; however, management practices intended to increase production can also affect ecosystem carbon (C) stocks. This study evaluated long-term (> 22 yr) ecosystem C responses to conversion of native grazing lands into more intensively managed silvopasture and sown pastures. Above- and below-ground C pools in each land use type were evaluated. Silvopasture exhibited the greatest total ecosystem C stock (168 Mg ha-1) compared with sown pasture and native rangeland (121 and 94 Mg ha-1, respectively). This response was due to the greater aboveground biomass (59 Mg ha-1 in silvopasture vs. 2.1 and 3.8 Mg ha-1 in sown pasture and native rangeland, respectively), primarily from the tree component. Soil organic C (SOC) accounted for 81 and 90% of total ecosystem C stocks in native rangeland and sown pasture, respectively, while in silvopasture SOC represented ~ 61% of total ecosystem C. Soil organic C increased from 76 Mg ha-1 in native rangeland to 110 Mg ha-1 sown pasture. Data indicated that grazing land intensification through the adoption of proper management promoted ecosystem C primarily due to increases in SOC and the associated benefit of a greater above-ground woody biomass.

Publications

• Type: Journal Articles Status: Published Year Published: 2015 Citation: Adewopo, J.B., Silveira, M.L., Xu, S., Gerber, S., Sollenberger, L.E., and Martin, T.A. 2015. Management intensification effects on autotrophic and heterotrophic soil respiration in subtropical grasslands. Ecological Indicators 56:6-14
• Type: Journal Articles Status: Accepted Year Published: 2016 Citation: Xu, S., Silveira, M.L., Inglett, K.S., Sollenberber, L.E., and Gerber, S. 2015. Effect of land-use conversion on ecosystem C stock and distribution in subtropical grazing lands. Plant and Soil (In Press).
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: 2. Silveira, M.L., Xu, S.*, Buonadio, G.*, Sollenberger, L.E., Inglett, K.S., Gerber, S. 2015. Management intensification impacts on soil organic carbon aggregate distribution in subtropical grazing land ecosystems. ASA-CSSA-SSSA Annual Meeting, Minneapolis, MN, November 15 - 18, 2015.
• Type: Journal Articles Status: Published Year Published: 2015 Citation: Adewopo, J.B., M. L. Silveira, S. Xu, S. Gerber, L. E. Sollenberger, T. Martin. 2015. Management intensification impacts on particle-size soil carbon fractions in subtropical grasslands: evidence from 13C natural abundance. Soil Science Society of America Journal 79:1198-1205.

Progress 10/01/13 to 09/30/14

Outputs
Target Audience: Our target audience included undergraduate and graduate students, visiting professors, and farmers Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? This project provided an unique opportunity for undergrad and graduate students as well as visiting professors to learn about the characteristics of soil C in the context of intensive grassland management systems How have the results been disseminated to communities of interest? Research data have been presented in scientific meetings as well as educational activities target farmers and youth. What do you plan to do during the next reporting period to accomplish the goals? We will continue with the data collection and laboratory analyses of the soil and plant samples collected in 2014.

Impacts
What was accomplished under these goals? Globally, grasslands support complex and interrelated ecosystem functions such as soil carbon(C) sequestration, nutrient cycling, water storage and quality preservation, biodiversity, livestock production, and wildlife. Rapid changes in land-use and management intensity within grasslands can lead to detrimental consequences, such as soil degradation, soil C depletion, and enhanced greenhouse gas emissions. Both intensity and type of management (e.g., fertilization regime, grazing intensity, stocking management, and conversion of native lands) applied to optimize grassland productivity can affect ecosystem C and soil organic matter storage. During this current report period, we start collecting data to determine the long-term impacts of land use conversion from native rangelands into improved pastures on the amounts and characteristics of soil C stocks across different regions and through different forms of grassland management. Our data demonstrated that grassland intensification resulted in increased soil organic C (SOC) stocks from 41 Mg ha-1 in the native rangeland to 62 and 69 Mg ha-1 in sown pasture and silvopasture, respectively. Additional C storage occurred in the live biomass of slash-pine trees in silvopasture (58 Mg ha-1), while the C accruing to woody biomass in native rangeland (3 Mg ha-1) was lost after conversion to sown pasture. Conversion to tree-integrated silvopastoral ecosystem favored the sequestration of a more stable. This research supports growing evidence that increasing intensity of grassland management is beneficial for soil and ecosystem C sequestration in the long-term, however, shifts in the allocation of C into ecosystem pools will likely have implication for biochemical cycling within this subtropical ecoregion.

Publications

• Type: Journal Articles Status: Published Year Published: 2014 Citation: Adewopo, J.B., M.L. Silveira, S. Xu, S. Gerber, L. E. Sollenberger, and T. Martin. 2014. Management intensification impacts on soil and ecosystem carbon stocks in subtropical grasslands. Soil Science Society of America Journal 78:977-986. Silveira, M.L., S. Xu.*, J. Adewopo*, A. J. Franzluebbers, and G. Buonadio*. 2014. Grazing land intensification effects on soil C dynamics in aggregate size fractions of a Spodosol. Geoderma 230-231:185-193.

Progress 07/24/13 to 09/30/13

Outputs
Target Audience: Our target audience included undergraduate and graduate students, visiting professors, and farmers. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? This project provided an unique opportunity for undergrad and graduate students as well as visiting professors to learn about the characteristics of soil C in the context of intensive grassland management systems How have the results been disseminated to communities of interest? Research data have been presented in scientific meetings as well as educational activities target farmers and youth. What do you plan to do during the next reporting period to accomplish the goals? We will continue with the data collection and laboratory analyses of the soil and plant samples collected in 2013.

Impacts
What was accomplished under these goals? A variety of management practices have been suggested to increase soil C sequestration potential. These include fertilization, grazing management, irrigation, and use of highly productive forage grass and legume species. Because improved management practices are normally beneficial to forage and livestock production, they may also provide an incentive for producers to adopt strategies that enhance soil C pools. In addition, C trading-related markets and the growing interest in C sequestration as mechanisms for environmental protection are also expected to enhance the economic value of the ecological services provided by grasslands. During this current report period, we start collecting data to determine the long-term impacts of land use conversion from native rangelands into improved pastures on the amounts and characteristics of soil C stocks across different regions and through different forms of grassland management. Our central hypothesis was that management practices intended to increase biomass production and land use intensification, such as converting rangelands into improved pasture systems and introduction of grazing livestock, control organic matter production, distribution and quality and, therefore, have major effects on C sequestration

Publications

• Type: Journal Articles Status: Published Year Published: 2013 Citation: 8. Silveira, M.L., Liu, K., Sollenberger, L.E., Follett, R.F., and Vendramini, J.M.B. 2013. Short-term effects of grazing intensity and nitrogen fertilization on soil organic carbon pools under perennial grass pastures in the Southeastern USA. Soil Biology and Biochemistry 58:42-49.