The Impact of Agricultural Systems on Soil Quality and Sustainability

Final Report for LS00-110

Project Type: Research and Education
Funds awarded in 2000: $191,263.00
Projected End Date: 12/31/2002
Region: Southern
State: North Carolina
Principal Investigator:
Mary Barbercheck
North Carolina State University
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Project Information


An interdisciplinary research project compared  soil attributes in agricultural systems: a best management practice (BMP) system; an integrated crop/animal system; an organic production system; a forestry/woodlot system; and a successional ecosystem.  Soil nematode population density maxima for most trophic groups were in July of each year. Three species of beneficial insect-parasitic nematodes, Steinernema carpocapsae,  S. glaseri and Heterorhabditis bacteriophora, and two insect-pathogenic fungi, Beauveria and Metarhizium, were isolated from the site. Cumulative abundance of soil microarthropods was greater in the organic, successional and BMP no-till treatments than in the Woodlot, BMP conventional till and pasture plots.    There was a trend for greater soil respiration (evolved CO2) and more rapid water infiltration in the organic compared to conventional systems. Likewise, penetrometer resistance, a measure of soil compaction, tended to be greater in the conventional system.  Carbon and N availability were consistently and significantly lower in grassland, forest and successional systems than in the two agricultural systems, whereas C availability was higher in the grassland and organic soils. High C availability and low N in grasslands significantly affected soil microbes and led to higher microbial biomass C:N ratios and lower N mineralization, suggesting a shift of microbial community composition.

Project Objectives:

1) develop indicators of soil quality for assessing ecological shifts related to sustainability (e.g. biotic and abiotic factors associated with low pest populations, increased crop health and/or tolerance to pest damage, and crop yield/quality)
2 ) determine the impact of agricultural system on selected soil organisms and soil chemical/physical indicators


Agriculture impacts soil biological, chemical, and physical properties through activities and processes such as cultivation and erosion, disposal of waste products, and chemical input from pesticides and fertilizers.  Soil organisms are functionally linked to above-ground interactions and are critical to organic matter decomposition and nutrient cycling, carbon storage, maintenance of plant diversity, biological control of human and agricultural pests, and bioremediation of pollutants.  As pesticide use becomes more restricted, it will be especially important to understand how particular production systems affect beneficial and pest organisms.  This information can be used to devise ways to exploit beneficial soil organisms, suppress pests, and enhance agricultural sustainability.
Systems of pest/crop management, pest suppression and pest prevention focusing on soil biology hold great promise for sustainable agricultural production; however, few research programs are able to undertake the high cost and labor-intensive endeavor to develop such systems. Recent funding and installment of a long-term systems experiment at the Center for Environmental Farming Systems (CEFS) near Goldsboro, NC,   presents an excellent opportunity to initiate a study of a systems approach to pest/crop management focusing on soil quality.  We propose to examine the effects of agricultural system on the biological, chemical and physical components of the soil which contribute to the reduction of initial pest populations, alter the carrying capacity of the system for pests, and increase the tolerance of hosts to pest injury.
Soil quality is at the center of the dialogue on issues related to agricultural sustainability.  Most agricultural practices alter soil biological, chemical and  physical properties, but they are not often viewed in terms of (or an opportunity for) managing beneficial soil organisms.  Questions to balance the goals of crop health/plant protection (e.g. constrain pathogens and consumers of plants) and soil quality (practices that benefit organic matter decomposition and nutrient cycling) must be addressed.  Rather than studying the effects of specific pest management tactics on a single type of pest,  examination of the effects of the agricultural system on the community of pest and beneficial organisms, soil fertility and crop productivity provides for a more holistic approach.  Development of indices associated with "healthy" soil, low pest populations and/or increased crop tolerance to pests will enhance our understanding of the relationship between soil characteristics and productivity in different agroecosystems.


Click linked name(s) to expand/collapse or show everyone's info
  • Steve Koenning
  • Frank Louws
  • Charles Raczkowski
  • Michael Wagger


Materials and methods:

Plots in the Long-term Farming Systems Trial at the Center for Environmental Farming Systems in Goldsboro, NC,  were sampled in May, July, and September of 2001, 2002, and 2003 to determine the effects of various production systems on selected soil abiotic and biotic characteristics.  Treatments include: Best Management Practices – Conventional till; Best Management Practices – No till; Organic; Old Field succession; Woodlot/Black Walnut; and Pasture. Each Treatment has three replications and five sampling points within each replication.

Research results and discussion:

Soil Physical and Chemical Properties:
Soil physical properties were measured on September 19, 2002 in the organic, BMP conventional, BMP no-till, crop/animal (pasture), trees (Black Walnut) and succesional systems. Measurements included soil bulk density, saturated hydraulic conductivity, total porosity, macroporosity, microporosity, plant available water, and field capacity.  No differences were found between systems for field capacity, hydraulic conductivity, plant available water retention and soil microporosity.  Bulk density was lowest in the organic system, a system that is tilled for the production of organic crops, and highest in the crop/animal system, a non-tilled environment compacted by the grazing activity of animals.  No differences in bulk density were found between the no-till, trees and successional systems. The soil total porosity data followed the same trend as the soil bulk density data. Interpretation of the distribution of pore space into macro- and microporosity reveals that changes occurring in total porosity resulted from changes in macroporosity. The hydraulic conductivity trend was consistent with the soil macroporosity data but no significant differences were found between systems

Soil chemical (pH, organic C, total N, NO3 and NH4-N), physical (bulk density, infiltration, and water-holding capacity), and biological(CO2 evolution) properties were measured as indicators of soil quality in five diverse agricultural systems from May-June 2002 and again in the fall following crop harvests.  Of the parameters measured, the most striking difference between systems occurred with the CO2 data for both sampling dates. In general, greater CO2 evolution was measured in spring vs. fall, most notably for the perennial agroforestry, pasture, and successional systems. Carbon evolved in the BMP no-tillage treatment was approximately two-fold greater than the conventional tillage system (490 vs. 240 kg C/ha/day) at the spring sampling date and only 18% greater (444 vs 376 kg C/ha/day) by fall. The pasture system was similar to the BMP no-tillage treatment in the spring, with intermediate values ranging from 160 to 280 kg C/ha/day observed for organic, crop/animal, agroforestry, and successional systems. Infiltration, measured as the time required for 2.54 cm of water to move into the soil, was notably faster in the organic system during spring and fall sampling periods compared to all other systems and reflects the reliance on cultivation as a weed management tool in organic production. After two years, these results continue to indicate a greater level of microbial activity in systems where previous crop/plant residues are maintained on the surface or where animal manures constitute part of the soil fertility regime.

Nematode communities:
Soil nematode population density maxima for most trophic groups was at the July sampling.  Population densities of nematodes feeding on bacteria and fungi were greater in organic treatments than in conventional cotton culture.  Higher densities of these free-living nematodes are probably a result of applications of organic sources of nitrogen including a winter cover crop.  Numbers of predatory nematodes were greatest in the woodlot and successional treatments than in other treatments.  Population densities of bacterial feeding nematodes were greater in no-till cotton than in conventionally-tilled cotton at all samplings. Numbers of fungal feeding nematodes were greater in no-till than in conventionally tilled cotton at the May and July samplings, but not at the September sampling.  Population densities of plant-parasitic nematodes were not affected by tillage regime. The total numbers of plant-parasitic nematodes were greatest in sweetpotato.  

Insect-parasitic nematodes and fungi:
Three species of beneficial insect-parasitic nematodes, Steinernema carpocapsa, S. glaseri and Heterorhabditis bacteriophora, and two insect-pathogenic fungi, Beauveria and Metarhizium, were isolated from the site.  Total entomopathogenic nematode cumulative abundance from 1999-2002 was greater in the BMP no-till, Woodlot and Successional plots than in the BMP contventional till, organic, and pasture plots.  S. carpocapsae, which tends to occur near the soil surface, appears to have been most severely affected by soil disturbance – tillage in the organic and conventional tillage treatments, and by compaction in the pasture.  H. bacteriophora, which tends to move throughout the soil profile, was more abundant in the  BMP conventional till than no-till plots.  S. glaseri was equally abundant across all treatments.  Insect-parasitic fungi was rarely dectected compared with the detection of insect-parasitic nematodes.  Metarhizium anisopliae was more commonly detected than Beauveria bassiana.  Detection in all treatmetns was similar, except for the pasture system, in which M. anisopliae was detected at about 2 to 5 times the frequency as in other systems.

Soil arthropods:
Microarthropods enhance microbial activity, accelerate decomposition, and mediate transport processes in soil.  Cumulative abundance of soil microarthropods was greater in the organic, successional and BMP no-till treatments than in the Woodlot, BMP conventional till and pasture treatments.  This pattern was driven by the abundance of soil mites, which comprised about 70% of the sampled arthropod community.  Collembola and all other arthropods comprised about 20 and 10% of the soil arthropod community, respectively.   Soil compaction in the pasture system may have contributed to the low numbers of arthropods detected there.  Collembolan abundance was positively correlated with percentage sand and macroporosity (r2 = 0.4) and negatively correlated with percentage clay microporosity (r2 = -0.4).    Using multivariate analysis (Fig. 1) 42% of the variation in abundance of soil organisms was explained by the first two dimensions.

Relationships among selected  soil abiotic and biotic characteristics:
Cumulative counts of soil organisms were used to assess whether differences in abundance among the agriculture/ecosystems were related to changes observed in management-sensitive physical measurements such as bulk density and macroporosity or to other soil characteristics. The beneficial insect-parasitic nematode, Steinernema carpocapsae, was more abundant in systems in which bulk density increased, with the exception of the pasture system. Similarly, macroarthropods appeared to be more abundant in systems that resulted in increased bulk density and lower macroporosity, in particular the successional, pasture and woodlot systems. Presence of other arthropods tended to be associated with soil properties that differed with soil type and did not change with management. Thus Collembolans were more abundant in soils which had low microporosity irrespective of the management system. Presence of the beneficial insect-parasitic nematode, Steinernema glaseri, was also associated with soils that were characterized by low microporosity and low soil moisture, and did not appear related to system effects.

Participation Summary

Educational & Outreach Activities

Participation Summary:

Education/outreach description:

Barbercheck,  M. Advanced Training in Organic Agriculture.  NE SARE Extension Professional Development workshop,  Feb. 28 – April 3, 2005.  Albany, NY.  20 attendees. (10 women)

Barbercheck,  M. Introduction to Organic Agriculture.  Nov. 19, 2004.  Agronomy Extension Agent In-Service.  University Park, PA

Barbercheck,  M. Organic Basics:  What to Organic Farmers Need?  2004 Fall CCA Continuing Education Seminar, Oct 29, 2004.  Grantville, PA.  15 attendees

Barbercheck, M. Displacement and persistence.  Third International Symposium of Entomopathogenic Nematodes and Symbiotic Bacteria. September 4-7, 2003, Arden Shishler Conference Center, Wooster, Ohio

Barbercheck, M. Aug. 13, 2004, The soil food web and soil quality: Letting the soil work for you. Northeast Organic Farming Association Annual Meeting, Amherst, MA

Barbercheck, M  Feb. 11, 2004, Soil Health, Soil Quality, Impacts on Residual Effects of Pesticide in No-Till.  Centre Region Crops Day.  Pleasant Gap, PA. 50 attendees (2 women)

Barbercheck, M. Feb. 5, 2004, Soil Quality: Making the Soil Work for You.  Southeast Pennsylvania Crops Conferences, Bucks Co.  80 attendees.

Barbercheck, M . Feb. 3, 2004 Soil Quality: Making the Soil Work for You.  Southeast Pennsylvania Crops Conferences, Montgomery Co.  200 attendees (10 women)

Barbercheck, M . The role of soil organisms in pest management.  4 March, 2003.  PSU Grounds staff in-service, University Park, PA.

Barbercheck, M . Conserving Beneficial Organisms in Soil, PSU Technical Service Pesticide Training, 6 January 2004, PSU

Barbercheck, M . Insect Pest Management in Organic Systems.  Lackawanna Co., Scranton, PA, 11 Dec. 2003. 15 attendees (4 women, 1 Asian man, 1 Asian woman)

Barbercheck, M., Mortensen, D. Building Pest Suppressive Soils: Research at Multiple Spatial Scales, USDA Sustainable Ag Lab, Beltsville, MD 26 February 2004

Barbercheck, M, Garling,, L.,  Seeley, S. Ten reasons why you should buy locally grown food.  Penn State Earth Day, 13 April 2003.  Invited.  

Barbercheck, M. The Impact of Agricultural Practices on Soil Organisms.  Ohio State University, Wooster, Entomology Departmental Seminar, 28 January 2003, invited.

Barbercheck, M. Soil Ecology Research.  Rodale Institute, 24 January 2003, invited.

Barbercheck, M . Organic Research at PSU.  Pennsylvania Certified Organic 2003 Annual Meeting, Dec 10, 2003. Millerstown, Perry Co., 75 attendees.

Barbercheck, M . Agronomy Extension In-Service, Beneficial organisms in agricultural soil, November 20-21, 2003, PSU

Barbercheck, M . Beneficial organisms in agricultural soil.  Ag Progress Days, 19-21, 2003.  Rock Springs, PA

Barbercheck, M . Creating a Research, Extension and Education Program Focused on Organic Agriculture: Lessons from the Center Environmental Farming Systems. Introduction to Organic Production Workshop. April 1-2, 2003, State College, PA.  70 attendees.

Barbercheck, M., The Soil Food Web.  Sustainable Soils Conference, Pittsboro, NC, 27 February 2003. 100 attendees.

Barbercheck, M. 2002. Response of Soil Organisms to Conventional and Alternative Agricultural Production Systems.   National  SARE  Conference, October 23-26, 2002, North Carolina

Barbercheck, M.  & A. Collins Soil Biology and Ecology. 2002.  NRCS Pasture Ecology Course. 13-24 May, 2002.

Barbercheck, M. and A. Collins. 2001. The Ground Crew - Soil Arthropods and Beneficial Organisms. SC Organic Grower's School. Columbia, SC, 22 September 2001.  

Barbercheck, Wagger, Koenning, Louws, Raczkowski. 2001.  Sustainable Agriculture Research at the Center for Environmental Farming Systems. Carolina Farm Stewardship Association 16th Annual Sustainable Agriculture Conference, Rock Hill, SC, Nov. 2-4, 2001.

Barbercheck, Wagger, Koenning, Louws, Raczkowski. 2001. Organic Agriculture Research at the Center for Environmental Farming Systems. Carolina Farm Stewardship Association 16th Annual Sustainable Agriculture Conference, Rock Hill, SC, Nov. 2-4, 2001.  

Barbercheck, Wagger, Koenning, Louws, Raczkowski. 2001. Soil Ecology at the Center for Environmental Farming Systems. Soil Ecology Society Conference, May 20-23, 2001, Calloway Gardens, GA.  

Barbercheck, M.  & M. Reeves. 2000. Assessing Soil Biological Activity on the CEFS Organic Unit Student Farm. Organic Farming and Cropping Systems Field Day, July 31, 2000.  CEFS, Goldsboro, NC.  

Bell, M.C., M.E. Barbercheck, F.J. Louws, and  M.G. Wagger. 2001. Qualitative and quantitative indicators of soil quality. Carolina Farm Stewardship Association 16th Annual Sustainable Agriculture Conference,  Rock Hill, SC, Nov. 2-4, 2001

Bell, M.C., M.E. Barbercheck, F.J. Louws, and M.G. Wagger. 2000.  Qualitative and quantitative indicators of soil quality.  Agronomy Society of America Annual Meeting 2000, p. 316 in Agronomy Abstracts, Agronomy Soc. Amer.  St. Paul, MN.  

Brownie, C., M.G._Wagger,_S.V. Woolard,  M.E. Barbercheck, M. Bell, N.G. Creamer, S. Hu, L. King, H.M. Linker, F.J. Louws, M.Marra, J.P. Mueller, C.W. Raczkowski..  Soil characteristic trends in the first two years of a long term study on the sustainability of agricultural systems. National  SARE  Conference, October 23-26, 2002, North Carolina

Collins, A.A., D. C. Fargo, and F. J. Louws. Characterization of bacterial communities in soil during the transition to organic agriculture. Phytopathology 92:S16.

Collins, A.A. and F.J. Louws. 2001. Characterization of bacterial communities isolated from soils under diverse management practices. Phytopathology 91: S18.

Greenwood, C. M., Barbercheck, M. Interactions between predators and entomopathogenic nematodes.  Entomological Society of America Annual Meeting Cincinnati, Ohio, 26-29 October 2003

Greenwood, C. M. and M. Barbercheck, Interactions between soil mites and entomopathogenic nematodes.  Sustainable Agriculture Research and Education Foundation (SARE) National Conference, Raleigh, North Carolina, 23-27 October, 2002  (with Mary Barbercheck)

Greenwood, C. M., Interactions between soil mites and entomopathogenic nematodes.  Acarological Society of America Annual meeting student competition, Montreal, Canada.  December 4-7, 2000.

Greenwood, C. M., Response of soil microarthropods to application of entomopathogenic nematodes.  ESA Annual Meeting, Atlanta, GA  Dec. 12-16,  1999  (with M.E. Barbercheck).

Koenning, S.R., M.E. Barbercheck 2002.  Influence of diverse agricultural systems on the population dynamics of free living, plant-parasitic, and entomopathogenic nematodes.  Nematology 34:254.

Koenning, S. and M. Barbercheck.  2002. Influence of diverse agricultural systems on the population dynamics of free-living, plant-parasitic and entomopathogenic nematodes.  Fourth International Congress of Nematology, 2002, Teneriffe  

Louws, F.J. Soil Biology and Plant Disease Management. 16 December 2003. For graduate level course in Soils. Fletcher,  NC.

Mueller, Barbercheck, Bell, Brownie, Creamer, Hu, King, Linker, Louws, Marra, Raczkowski, Susko, Wagger.  2001. Desarrollo y Implementacion de un Estudio de Sistemas Agricolas al Gran Escala y Larga Duracion. I Simposio Internacional sobre Ganaderia Agroecologica,  La Habana, Cuba, 6-8 December, 2001.  

Mueller, Barbercheck, Bell, Brownie, Creamer, Hu, King, Linker, Louws, Marra, Raczkowski, Susko, Wagger.  2001. Investigaciones Sobre la Ecologia del Suelo en el Centro de Sistemas Agricolas Ambientales. IV Taller Internacional sobre Recursos Fitogeneticos, Sancti Spiritus, Cuba, 3-4 December, 2001.  

Raczkowski, C. Measuring soil physical characteristic trends in a long term study on the sustainability of agricultural systems. Sustainable Soils Conference,  Pittsboro, NC, 27 February 2003.

Tu C., S. Hu, S.R. Koenning, and K.R. Barker. 2002. Root-parasitic nematodes impact microbial biomass and nitrogen mineralization in six soils. Abstracts of ASA-CSSA-SSSA 2002 Annual Meetings (CD-ROM version). ASA-CSSA-SSSA, November 10-14, Indianapolis, IN.

Wagger, M.,  Raczkowski,, C.  Bell, M. 2002. Soil Physical and Chemical Properties Research at the Center for Environmental Farming Systems. National SARE  Conference, October 23-26, 2002, North Carolina

ZHANG, W., H. D. Shew, M. Barbercheck and S. Hu Nematodes and collembola significantly reduce disease incidence caused by the pathogen, Pythium ultimum, in tomato.  American Phytopathological Society, Aug. 9-13, 2003.  Charlotte, NC

Project Outcomes

Project outcomes:

Time of sampling may affect conclusions as to which soil characteristics are most dominant and or important in measuring soil quality.  These results will be used to determine indicators of ecosystem health.  Over the last three years differences among the various systems are beginning to be expressed.  Future research may be able to focus on identification of taxa to determine indicator species.  Approximately 500 people were introduced to the concepts and components of soil quality through field events at the site and through presentations at meetings.


Areas needing additional study

Further analyses of data for interactions among the measured soil characteristics and crop yield/quality are being conducted.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.