112.3

-To show that intense management can increase the rate at which soil quality improves

-To compare soil quality between two different management intensities (greenhouse beds and fallow fields) by testing the following soil properties:

-% Soil Organic Matter (SOM)-pH-Cation Exchange Capacity (CEC)-% base cation saturation ([Ca2+],

[Mg2+])

Comparison of soil properties in raised bed greenhouse and adjacent fallow fields: effects of 3 years of intense

organic management at the Jones Farm Ona Lindauer, Shannon Morris, Rob StengerResearch Project for Systems Ecology (ENVS 316) Fall ‘04

Oberlin College, Oberlin, OH

Main Objective -Our two study areas were 1) intensively managed

greenhouse beds (planted in April 2002 after leaf mulch and chicken manure fertilization)

2) unmanaged fallow fields (uncultivated since 2000)

Methods

Results & Discussion

1)Three years of intense management will give the greenhouse beds a higher SOM.

2)Higher SOM in greenhouse beds will lead to a higher CEC

3)Higher pH in greenhouse beds will lead to a higher % base cation saturation

-Greater SOM content and higher pH mean more cation exchange sites for base cations to occupy.

-Higher SOM found in intensively managed organic agricultural soils may have a higher CEC than soils which do not receive high inputs of organic material.

-A higher pH may lead to a higher CEC.

-The rate of soil quality improvement observed as a result of intensive soil management at the Jones Farm can be used to guide agricultural practices elsewhere.  

-The Jones Farm is an organic farm managed as part of the Oberlin Sustainable Agriculture Project since 2000, prior to which the farm was under conventional roundup-ready soybeans cultivation.

-Soil quality has not been fully assessed since 2000.

-Current assessment could inform future management decisions in soil development.

N

F4

F3

F2 F1

GA

GB

The Jones Farm located in Northeast Ohio with sample areas. GA and GB are the greenhouses. F1-4 are the fallow field sample sites.

Comparison of average soil properties from averaged sub-plot data at Jones Farm, with standard error bars and base cation concentrations adjusted for scale. Differences in pH, % SOM, CEC, [Mg2+], and [Ca2+] between our two sample sites were all highly significant.

Conclusion

Hypotheses

Background-We used standard techniques (Petersen 2004) to extract soil cations and assess CEC with sequential additions of NH4Cl and KCl.

-CEC was measured from the ammonium extract using an ammonium probe, base cation concentrations were assessed using a Dionex Ion Chromatograph

-% SOM was measured via combustion and pH was taken with a pH probe.

Regression between SOM and CEC in soil samples from individual sub-sample plots at Jones Farm. R2 value shows the strength of the relationship.

Regression between pH and CEC in soil samples from individual sub-sample plots at Jones Farm. R2 value shows the strength of the relationship.

R2 = 0.9603

0

5

10

15

5 10 15 20SOM (%)

CE

C (

cmo

l (+

)/kg

)

R2 = 0.7249

0

5

10

15

5.0 5.5 6.0 6.5 7.0 7.5pH

CE

C (

cmo

l (+

)/kg

)

Field Greenhouse

R2 = 0.9603

R2 = 0.7249

Works CitedPetersen, J.E. 2004. Methods for analyzing aquatic ecosystems, unpublished.