1) Agricultural soil contains a diversity of organisms including billions of bacteria and fungi per teaspoon, as well as protozoa, nematodes, arthropods, and earthworms. 2) Management goals should include maintaining productivity while improving soil properties and the health of both plants and beneficial organisms. This can be achieved through practices like crop rotations, minimizing tillage, and adding organic matter. 3) Reduced and no-till practices favor bacteria over fungi but can increase the abundance and diversity of soil arthropods compared to conventional tillage. Cover crops also support higher numbers of beneficial predators and microarthropods.

1. Effects of Soil Management on
Soil Organisms
Mary Barbercheck Dept. of Entomology
Penn State University

2. In 1 teaspoon of agricultural soil there are…
 Bacteria 100 million to 1 billion
 Fungi 6-9 ft fungal strands put end to end
 Protozoa Several thousand flagellates & amoeba
One to several hundred ciliates
 Nematodes 10 to 20 bacterial feeders and a few fungal feeders
 Arthropods Up to 100
 Earthworms 5 or more

4. Elliot & Coleman. 1988. Ecol. Bull. 39: 23-32

5. Some Goals of Soil Management
• Manage system for
productivity and
beneficial processes
• Improvement in abiotic
and biotic properties of
soil
• Improvement of plant
health
• Conservation of
beneficial organisms
• Suppression of pests

6. Crop Rotations
Know Your Pest
Above-Ground Diversity to
Reduce Pest Habitat
Favor Beneficials
Provide Beneficial Habitat
Minimal Pesticide Use
Pest and Disease Suppression
Healthy Soil Add Organic Matter
Crop
Rotations
Minimize Tillage to
Below-Ground Diversity
Conserve OM
Minimal Use of
Synthetic

7. Effects of Agricultural
Management on Soil Arthropods
• Densities are much
lower than in
Predators
unmanaged (@ 10% of consumers)
systems, regardless
of level and types of Consumers
inputs (@ 10% of producers)
• Favors bacteria over
fungi Producers
• Soil arthropods tend
to consume fungi Energy Pyramid
(After Moldenke, 2002)

8. Implication of Bacterial Dominance in Soil
Typical Ratio B:F >10:1
Bacterial-based Fungal-based
Predatory Arthropods (0.0001x)
Predatory Arthropods (0.01x)
Predators of BFN (0.001x)
BF Nemas (0.01x) FF Invertebrates (0.1x)
Protozoa (0.1x)
Fungi (x)
Bacteria (x)
(After Moldenke, 2002)

9. Some Factors Affected by Tillage
• Soil Moisture
• Soil Temperature
• Range of Temperature
and Moisture
Fluctuations
• Surface Residue
• Soil Fauna Abundance
and Diversity
• Plant Diversity
• Favors Bacteria > Fungi

10. Tillage Effects on Soil Arthropod
Abundance & Diversity in Corn
Goldsboro, NC
No Till Conv. • Richness: No. of taxa
Till
• Simpson’s: probability that 2
No. 2781 1369 species selected at random will
be the same; 0 to 1; diversity
decreases as index increases
Richness 107 88
• Shannon’s: uncertainty in
predicting identity of organism
Simpson .135 .058 chosen at random; equals zero
when only 1 species present
Shannon 2.93 3.38 • Evenness: 1=all taxa in similar
numbers, as approach 0,
Evenness .396 .566 divergence from evenness,
some taxa more dominant

11. Ave. No./Core Ave. No./Core
5/ 5/
14 14
5/ / 19 5/ / 19
0
0.2
0.4
0.6
0.8
1
1.2
1.4
0
0.2
0.4
0.6
0.8
1
1.2
1.4
21 97 21 97
5/ /19 5/ /19
28 97 28 97
/ /
6/ 199 6/ 199
4/ 7 4/ 7
6/ 19 6/ 19
11 97 11 97
6/ / 19 6/ / 19
18 97 18 97
6/ /19 6/ /19
25 97 25 97
/ /
7/ 199 7/ 199
2/ 7 2/ 7
1 1
7/ 99 7/ 99
9/ 7 9/ 7
7/ 19 7/ 19
16 97 16 97
7/ / 19 7/ / 19
23 97 23 97
Conventional
Conventional
7/ /19 7/ /19
30 97 30 97
/1 /1
8/ 99 8/ 99
6/ 7 6/ 7
8/ 19 8/ 19
13 97 13 97
No-till
No-till
S. carpocapsae
8/ / 19 8/ / 19
H. bacteriophora
20 97 20 97
8/ / 19 8/ / 19
27 97 27 97
/1 /1
9/ 99 9/ 99
3/ 7 3/ 7
19 19
97 97
Ave. No./Core
5/
14
5/ /19
0
0.2
0.4
0.6
0.8
1
1.2
1.4
21 97
5/ /19
28 97
/1
6/ 99
4/ 7
6/ 19
11 97
6/ / 19
18 97
Nematodes in Maize
6/ / 19
25 97
/
7/ 199
2/ 7
1
7/ 99
9/ 7
No-till
7/ 19
S. riobrave
16 97
7/ /19
23 97
7/ / 19
30 97
/1
8/ 99
6/ 7
8/ 19
13 97
Conventional
Effects of Tillage on Entomopathogenic
8/ /19
20 97
Millar & Barbercheck, 2002
8/ / 19
27 97
/1
9/ 99
3/ 7
19
97

12. Effects of Tillage and Cover Crops
on Pest & Beneficial Arthropods in Soil
Peachy et al. 2002. Applied Soil Ecology 21: 59-70
100 300 3
250 2.5
80
CC Dry Matter MT/ha
200 2
Symphyllans/m2
Predators/m2
60
150 1.5
40
100 1
20 50 0.5
0 0 0
Mustard Barley Rye Fallow Oats Mustard Fallow Barley Oats Rye
Macropredators Pred. Mites CC Dry Matter
Conv. Till Direct Seed Till

13. Effects of Cover Crop Rye Management
in Reduced Tillage Corn
Clark et al. 1993. J. Entomol. Sci. 28: 404-416
Predators
a
30 ab
25
Mean No./Plot
20
bc
15
10 c
5
0
R
Pa
Fa
R
ol
em
llo
ra
l
qu
ov
w
/D
e
at
is
k

14. Effects of Cover Crop Rye Management
in Reduced Tillage Corn
Clark et al. 1993. J. Entomol. Sci. 28: 404-416
Roll Paraquat Remove Fallow/Disk
6 a a
a
5
Mean Number
a
4
aa
3 ab
bb
2
b b
1 b
0
C
St
Li
Ly
C
ar
oc
ny
ap
co
ab
ci
ph
hy
si
ne
id
da
iid
lin
ae
lli
e
ae
id
da
ae
e

15. Effect of Organic & Mineral Fertilizers in Alfalfa
Fratello et al. 1989. Agric. Ecosyst. Envt. 27: 227-239
Collembola Mites Other
120
100
#/m2 (x 1000)
80
60
40
20
0
St
M ud
Po in
W e
Sh
Ve in
M
C ry l
Sl ol
St
on
in ge
ax
or
.
ud
ra
ul era
ee
tc era
Sl
m
M
tr
w
t
h
g
M
p
l

16. Effect of Compost Type on Microbial Biomass N
and Soil Arthropods
Gunadi et al. 2002. Eur. J. Soil Biol. 38:161-165
Mites Collembola Other
Vermicomposts
10000 Trophic
2500 2 6 4 7
Log Mean Number
Groups
2000 1000
1500
mg/kg
100
1000
500 10
0 1
Fo
Pa
C
C
ow
om
Pa
C
Fo
C
od
pe
om
ow
po
r
M
W
od
p
an
st
er
as
po e
M
ur
W
te
e
an
st
as
u
t
Microbial Biomass N
re

17. Systems Experiment 1999-2002
Microarthropods Cumulative Average
180
160
140
120
Ave. #/Core
100
Other
80
Coll.
60
Mites
40
20
0
Pasture BMP Trees BMP Old Organic
CT NT Field
Barbercheck, unpubl.

19. Systems Experiment 1999-2002
EPN & EPF Cumulative Average
S.c. H.b. S.g. Fungi
10
8
Ave. #/Core
6
4
2
0
Organic BMP CT Pasture BMP NT Trees Old Field
Barbercheck, unpubl.

20. BMP for Management of
Soil Organisms
• Systems effects can arise
from very complex direct and
indirect interactions
• Minimize compaction
• Provide continuous energy
(e.g., cover crops)
• Reduce tillage to favor
fungal-based food webs
• Provide refuges for mobile
predators Cosmochthonius (Oribatida)
• Rotate crops to reduce pest D. Walter
organisms
• Reduce use of biocides

21. Web Resources
• Soil Biodiversity Portal
www.fao.org/ag/AGL/agll/soilbiod/default.htm
• Soil Biology Primer
http://www.swcs.org
• USDA Soil Quality Institute http://soils.usda.gov/sqi/
• Appropriate Technology Transfer for Rural Areas
http://www.attra.org/
• Earthworms: The agriculturist’s friend
http://www.eap.mcgill.ca/publications/eap6.htm

22. The End
Photo by M. Greenwood