The Impact of Agricultural Systems on Soil Quality and Sustainability

2002 Annual 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

The Impact of Agricultural Systems on Soil Quality and Sustainability

Summary

Soil in plots in the Long-term Farming Systems Trial at the Center for Environmental Farming Systems were sampled in May, July, and September of 2001 and 2002, 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. Results of this research and a list of publications and presentations are given.

Objectives/Performance Targets

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

Accomplishments/Milestones

Plots in the Long-term Farming Systems Trial at the Center for Environmental Farming Systems were sampled in May, July, and September of 2001 and 2002, 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.

Impacts and Contributions/Outcomes

Results

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. Plans are to continue yearly measurements of these properties on each system.

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.

Soil Biology

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 sweet potato culture.

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.

Impacts

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. Multivariate analysis of the soil biotic and abiotic data will help determine linkages among soil biotic and abiotic characteristics.

Several presentations have been made at scientific meetings and extension/outreach events to disseminate the results of this work.

Contributions/Outcomes

Publications
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.

Millar, L. C. and M. E. Barbercheck. 2002. Effects of tillage practices on
entomopathogenic nematodes in a corn agroecosystem . Biological Control 25: 1-11.

Mueller, J. P., M. E. Barbercheck, M. Bell, C. Brownie, N. Creamer, A. Hitt, S. Hu, L.
King, H.M., Linker, F.J. Louws, S. Marlow, M. Marra, C. W. Raczkowski, D. J.
Susko, and M.G. Wagger. 2002. Development and Implementation of a Long-Term Agricultural systems Study: Challenges and Opportunities. HortTechnology 12: 362-368.

Millar, L. C. and M. E. Barbercheck. 2001. Interaction between endemic and introduced entomopathogenic nematodes in corn. Biological Control. 22: 235-245.

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

Interactions between predators and beneficial nematodes. M. Newman and M. Barbercheck. National SARE Conference, October 23-26, 2002, North Carolina

Soil characteristic trends in the first two years of a long term study on the sustainability of agricultural systems. C. Brownie, 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. National SARE Conference, October 23-26, 2002, North Carolina

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

The Soil Food Web. Sustainable Soils Conference, Pittsboro, NC, 27 February 2003.
Response of Soil Organisms to Conventional and Alternative Agricultural Production Systems . Barbercheck. National SARE Conference, October 23-26, 2002, North Carolina (Barbercheck).

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

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

Interactions between predators and beneficial nematodes. M. Newman and M. Barbercheck. National SARE Conference, October 23-26, 2002, North Carolina

Soil Life: Putting it to work. PAES Lime & Fertilizer Conference. The Penn Stater, University Park, PA, January 22, 2003. Workshop/presentation 2 presentations, approximately 75 attendees each (Barbercheck and Bruns)

Soil Life. 3rd Annual Pest Management Tour. Southeast Research and Extension Center, Landisville, PA. 11 July 2002. 2 presentations, approximately 50 attendees each. (Barbercheck)

Soil Biology Research at the Center for Environmental Farming Systems. National SARE Conference, October 23-26, 2002, North Carolina (Barbercheck, Louws, Fager)

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

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

Ecological Approaches for Sustainable Pest Management. Dept. of Entomology Extension Seminar. Penn State University. 25 Sept. 2001 (Barbercheck)

The Ground Crew – Soil Arthropods and Beneficial Organisms. SC Organic Grower’s School. Columbia, SC, 22 September 2001. (Barbercheck and Collins)

Transition strategies to organic production systems: economic and environmental indicators. Center for Environmental Farming Systems Field Day, July 9, 2001.(Barbercheck)

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)

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. (Mueller, Barbercheck, Bell,
Brownie, Creamer, Hu, King, Linker, Louws, Marra, Raczkowski, Susko,
Wagger)

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)

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)

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.)

Conservation of Insect Pathogens in the Soil. Invited speaker. IOBC-ESCOP
meeting, The Practice of Biological Control: Importation and management
of natural enemies and agents. Aug. 2-5, 2001, Bozeman, MT

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

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

Interaction between soil mites and entomopathogenic nematodes. Entomological Soc. America Annual Meeting, Dec. 3-7, 2000. Montreal, Canada (C. M. Newman & M.
Barbercheck)

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. (Bell, M.C., M.E. Barbercheck, F.J. Louws,
and M.G. Wagger.)

Advances in Organic Research: Soil Biology and Beneficial Organisms.
Sustainable Agriculture Conference. Wilmington, NC, Nov. 3-5, 2000. (Barbercheck, Wagger, Koenning, Louws, Raczkowski)

Soil Biology and Quality. NRCS training seminar. Raleigh, NC. Sept. 21, 1999.
Non-Target Effects of Entomopathogenic Nematodes. IOBC International Symposium “Evaluating Indirect Effects of Biological Control . 10/17-20, 1999. Montpellier, France (M. Barbercheck & L. C. Millar).

Collaborators:

Frank Louws

frank_louws@ncsu.edu
Assistant Professor and Extension Specialist
North Carolina State University
Department of Plant Pathology
Box 7616
Raleigh, NC 27695-7616
Office Phone: 9195152730
Charles Raczkowski

razcowc@ncat.edu
Associate Professor
NC A & T University
Natural Resources and Environmental Design
Greensboro, NC 27411
Office Phone: 3303347543
Michael Wagger

michael_wagger@ncsu.edu
Professor
North Carolina State University
Department of Soil Science
Box 7619
Raleigh, NC 27695-7619
Office Phone: 9195152655
Steve Koenning

srkpp@unity.ncsu.edu
Senior Researcher and Extension Specialist
North Carolina State University
Department of Plant Pathology
Box 7616
Raleigh, NC 27695-7616
Office Phone: 9195152730