Response of soil invertebrates to reduced tillage systems

established on a clay loam soil

P. Neavea, C.A. Foxb,*

a Agriculture and Agri-Food Canada, Eastern Cereal and Oilseeds Research Centre, Ottawa, Ont., Canada K1A 0C6b Agriculture and Agri-Food Canada, Southern Crop Protection and Food Research Centre, 1391 Sandford St., London, Ont.,

Canada N5V 4T3

Received 26 July 1996; received in revised form 28 March 1997; accepted 1 August 1997

Abstract

The response of both the cryptozoic macroarthropod community (large soil invertebrates that live and/or hide on the soil

surface) and soil micro and meso-arthropods (Acarina and Collembola) is described with respect to abundance (number of

individuals) and richness (number of family groups) when no-till, chisel plow, and ridge-tillage systems were established on a

clay loam soil (Typic Haplaquoll) having a previous history of conventional tillage. Except for the September sampling date,

in 1988, abundance of cryptozoic fauna was higher in no-till than in conventional tillage: 30 taxonomic families were

collected in comparison to 22 for conventional tillage. In 1989, trends in abundance and richness were not consistent in no-till

and conventional tillage; chisel plow was similar to no-till; and ridge-tillage was similar to conventional tillage after severe

soil disturbance by ridging. In 1988, mean soil arthropod abundance and richness were signi®cantly higher in no-till than in

conventional tillage plots from June to the end of August but not in October. In 1989, for no-till, chisel plow, and conventional

tillage, there were signi®cant sampling depth and cultivation by depth interaction effects on total soil arthropod abundance.

# 1998 Elsevier Science B.V.

Keywords: Soil arthropods; Cryptozoic fauna; Abundance; Richness; Reduced tillage

1. Introduction

In 1988, in Eastern Ontario, reduced tillage, which

may include such agronomic practices as no-till,

chisel plow or ridge-tillage, was not a common prac-

tice on heavy textured soils such as clays and clay

loams because of compaction problems as well as cold

temperatures and moist soil conditions in early spring.

Consequently, research was undertaken in 1988 to

characterize effects on various chemical and physical

attributes (Dwyer et al., 1996) of converting from

conventional tillage to reduced tillage on clay loam.

Varying intensities of mechanical disturbance from

different tillage operations will impact directly and

indirectly on the suitability of habitats for soil inver-

tebrates. For example, moldboard plowing is consid-

ered to be detrimental to soil faunal population

(Edwards and Lofty, 1975) when compared to no-till

practices and natural ecosystems because of the sub-

Applied Soil Ecology 9 (1998) 423±428

*Corresponding author. Fax: 519 457 3997; e-mail:

foxc@em.agr.ca

0929-1393/98/$19.00 # 1998 Elsevier Science B.V. All rights reserved.

P I I S 0 9 2 9 - 1 3 9 3 ( 9 8 ) 0 0 1 0 0 - 0

stantial soil disturbance that occurs annually. Less is

known about the soil invertebrate response to chisel

plow and ridge-till systems on clay soils. Loring et al.

(1981) observed that acarine and collembolan popula-

tions in a loamy sand soil were increased or unaffected

by chisel plow tillage compared with moldboard and

no-till.

The objective of this study was to determine

whether establishment of reduced tillage practices

on a clay loam with a previous history of conventional

tillage (moldboard plowing and disking) and cropping

to corn had an immediate and lasting effect on abun-

dance and taxonomic richness of the soil invertebrate

community.

2. Materials and methods

2.1. Experimental site

The study was located west of Ottawa, Ont., Canada

(Lat. 458220N; Long. 758430W) on a clay loam soil

classi®ed as a Typic Haplaquoll (Soil Survey Staff,

1992). In 1987, a randomized complete block, split

plot design was established with four blocks each

including four tillage treatments: conventional, chisel

plow, no-till and ridge-till. Sampling was con®ned to

plots with continuously grown corn.

In 1988, 6.6 l haÿ1 of Dual1 (metolachlor) and

6.6 l haÿ1 of atrazine were applied to the tillage plots,

and in 1989, 3.1 l haÿ1 Dual1 2.4 l haÿ1 Roundup1

(glyphosate) and 1.2 l haÿ1 Banvel1 (dicamba) were

applied. In both 1988 and 1989, nitrogen (urea) at

172 kg N haÿ1 was broadcast and phosphorus and

potassium were banded at 60 kg haÿ1. For conven-

tional plots, fall moldboard plowing with one pass of a

disc-harrow prior to spring planting was undertaken

each year. No cultivation was undertaken on no-till

plots except for disturbance of 0.10 m wide slot for

seed planting. Ridge-till plots were treated initially

as no-till plots, with shallow cultivation at post-

emergence of the corn, and in June, prior to canopy

closure, ridges were formed in the rows with a culti-

vator. Chisel plow plots were fall chisel plowed with

one pass of a disc-harrow at spring cultivation. On

May 6, 1988, Pioneer 3953 and on 10 May 1989,

Pioneer 3902 was planted at 65 000 plants haÿ1.

Additional information with respect to history, soil

compaction and rooting depth is reported in Dwyer

et al. (1996).

2.2. Sampling methods and analyses

Cryptozoic fauna, the larger soil invertebrates that

live and/or hide on the soil surface, and soil meso-

arthropods (Acarina and Collembola) were sampled.

In the ®rst year (1998), soil arthropod sampling was

restricted to two no-till and two conventional tillage

plots. Twelve undisturbed soil core samples (7.5 cm in

diameter, 5 cm deep) were taken per plot on 15 June, 7

July, 3 and 31 August, and 5 October. In 1989, the

study was expanded to include the chisel plow treat-

ment which is intermediate between moldboard plow-

ing and no-till with respect to mechanical disturbance

(Loring et al., 1981). From each plot, ®ve samples

were taken from 0±5 cm and 5±10 depths on 28 May,

19 June, 17 July, 10 August and 10 October. Soil

arthropods were extracted using a modi®cation of the

Merchant±Crossley extractor (Norton, 1985).

The cryptozoic faunal community was sampled

with cryptozoa boards (Cole, 1946) consisting of

30�30 cm pieces of plywood board placed randomly

on the surface between rows. Soil invertebrate counts

from cryptozoa boards only provide information on

relative frequency of occurrence and do not represent

absolute estimates of population size. From May to

October 1988, 12 replicates were sampled in no-till

and conventional plots. In 1989, sampling was

expanded to include chisel plow and ridge-till plots.

Identi®cation of soil invertebrates were made to

family level, or identi®able family groups. Abundance

was de®ned as the number of individuals obtained

from a sample, and richness as the number of family

groups in a sample.

An analysis of variance (Minitab Inc., 1996) split-

plot model was used for the 1989 data to determine if

there were signi®cant effects of tillage and soil depth

on the abundance and richness of soil arthropods. The

results reported are for untransformed data; similar

results were obtained when the data were log-trans-

formed. For 1988 data, a t-test (Snedecor and Cochran,

1989) and for 1989 data, a Tukey studentized range

test (SAS Institute, 1989) was used to determine for

each sampling date if signi®cant differences in abun-

dance and richness of cryptozoic invertebrates and soil

arthropods existed amongst the tillage practices.

424 P. Neave, C.A. Fox / Applied Soil Ecology 9 (1998) 423±428

3. Results and discussion

3.1. Cryptozoic fauna

In 1988, except for one sampling date (9/18),

abundance and richness of cryptozoic fauna were

greater in no-till than in conventional tillage

((Fig. 1(a) and (b)), respectively). The reason for

the marked increase in cryptozoic invertebrates of

September 18 is not known. However, the two systems

gradually become more similar in terms of abundance

and richness towards the end of the growing season,

suggesting that with increasing time from initial

mechanical disturbance in spring, cryptozoic inverte-

brate populations in conventional tillage can recover.

The difference in abundance and richness in the ®rst

year following establishment of no-till was likely due

to initiation of residue cover which provided shelter

and a food source as well as reduced mortality due to

elimination of plowing (Edwards and Lofty, 1975).

Overall, in the no-till system, 30 taxonomic families

were collected in comparison to 22 conventional

tillage.

In 1989, trends in abundance and richness of cryp-

tozoic fauna (Table 1) in the no-till and conventional

plots were less consistent during the growing season.

By September, there was no signi®cant difference in

abundance between no-till and conventional, but there

were signi®cantly more taxa in no-till plots. Under

chisel plow, abundance was not signi®cantly different

from no-till suggesting that residues remaining on the

surface and the reduced tillage disturbance had a

positive effect on populations. Abundance and rich-

ness of cryptozoic fauna in the ridge-tilled system

were initially not signi®cantly different from the other

three tillage systems; but, after ridging took place on

June 24, values were similar to those in conventional

tillage for the remainder of the sampling season

indicating that the severe soil disturbance caused by

ridging had a direct impact on cryptozoic invertebrate

numbers.

3.2. Soil arthropods

For 1988, mean abundance and mean richness of

soil arthropods ((Fig. 1(c) and (d)), respectively) were

signi®cantly higher from June to the end of August in

no-till when compared with conventional tillage. By

October, soil arthropod abundance was signi®cantly

higher in conventional tillage and richness was not

signi®cantly different, indicating that, given suf®cient

Table 1

Mean abundance and mean richness of cryptozoic invertebrates per sample in 1989

Sample

date (1989)

Tillage treatment

No-till Ridge-till Chisel plow Conventional

Mean

abundance a

Mean

richness b

Mean

abundance

Mean

richness

Mean

abundance

Mean

richness

Mean

abundance

Mean

richness

11 June 20 a 6.5 a 27.5 a 9.5 a 18 a 6 a 12 a 7.5 a

11 June 11 a 11 a 6 a 6 a 7.5 a 7.5 a 6.5 a 6.5 a

25 June 27 ab 8.5 ab 3 b 2 c 40.5 a 13.5 a 18 ab 5 bc

5 July 12.5 ab 7 a 3 b 2.5 b 16.5 a 5.5 ab 4 b 2.5 b

15 July 16 a 8 a 7.5 a 4 b 12 ab 3.5 b 8 b 3.5 b

17 July 12.5 a 5.5 a 8 a 4.5 a 17 a 6.5 a 5.5 a 3.5 a

23 July 7 a 4 a 2 a 2 a 6 a 4 a 3.5 a 2.5 a

10 August 14 a 6.5 a 5.5 b 3 b 9 ab 4.5 ab 7.5 ab 5 ab

17 August 8.5 a 4.5 a 1.5 b 1.5 a 6 ab 4 a 2.5 a 2.5 a

9 September 10 a 5.5 a 5 b 3 a 10 a 5 a 9.5 a 4.5 a

24 September 9.5 a 5.5 a 5.5 a 2.5 b 5.5 a 3 a 4 a 2.5 b

a Mean abundance (number of individuals per sample).b Mean richness (number of family groups per sample).

The same letter following a mean for the same sample date indicates there is no significant difference (p�0.05) between tillage treatment [by

Tukey's test (SAS Institute, 1989)].

P. Neave, C.A. Fox / Applied Soil Ecology 9 (1998) 423±428 425

Fig

.1

.R

esult

sfo

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ill

and

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r1988

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idual

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(b)

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ple

of

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arth

ropods.

426 P. Neave, C.A. Fox / Applied Soil Ecology 9 (1998) 423±428

time without soil disturbance, soil arthropod numbers

are able to recover within the growing season.

For 1989, there were signi®cant sampling depth and

cultivation by depth interaction effects ( p�0.001) on

total soil arthropod abundance. Sampling depth had a

signi®cant in¯uence on acarine richness ( p�0.05), and

on total soil arthropod richness ( p�0.03). Mean abun-

dance of soil arthropods at 0±5 cm was signi®cantly

higher in chisel plow than in no-till and conventional

plots on 28 May (Table 2); but, for the June and July

sampling dates, there were no signi®cant differences

in abundance amongst the three tillage treatments.

Mean richness was also signi®cantly higher on 28 May

in chisel plow compared to conventional plots, but not

signi®cantly different from no-till, suggesting that the

presence of residues and reduced mechanical distur-

bance had an in¯uence on number of family groups.

This effect on mean richness of soil arthropods was

not sustained through the growing season, with no

signi®cant differences amongst the three tillage treat-

ments being recorded in June, July and October. By 10

August, mean abundance in no-till at 0±5 and 5±10 cm

was signi®cantly lower than in chisel plow but not

different from that in conventional plots. At the 5±

10 cm depth in no-till, mean richness was signi®cantly

different from that in chisel plow and conventional

treatments. For conventional and chisel plow, soil

arthropod abundances were greater at the 5±10 cm

depth then at the 0±5 cm depth, suggesting that move-

ment by the soil arthropods had occurred. Winter et al.

(1990) noted the migrations of microarthropods in

conventional treatment occurred as a result of dry

conditions. In fact, movement to the 5±10 cm depth

in the conventionally tilled soil was already apparent

on the 19 June sampling date (Table 2) and numbers

remained higher at this depth for the remainder of the

growing season. In comparison, downward movement

was not observed in chisel plow plots until August,

suggesting that chisel plow tillage provided more

suitable conditions at the surface for a longer time

period. Arthropod abundances remained fairly similar

at both sampling depths in no-till plots during July and

August, suggesting a moderating effect of surface

residues on moisture and temperature. By 7 October,

mean abundance of soil arthropods at 0±5 cm in no-till

was signi®cantly higher than in either chisel plow or

conventional plots, while there were no signi®cant

differences in abundance between chisel plow and

conventional treatments. This suggests that the residue

cover was suf®cient under no-till conditions to pro-

mote increases in numbers. Observations from this

study indicate that cryptozoic invertebrates and Acar-

ina and Collembola respond relatively quickly to

changes in agronomic practices.

Table 2

Mean abundance and mean richness of soil arthropods per sample in 1989

Sampling

date (1989)

Sampling

depth (cm)

Tillage treatment

No-till Chisel plow Conventional

Mean

abundance a

Mean

richness b

Mean

abundance

Mean

richness

Mean

abundance

Mean

richness

28 May 0±5 19.2 b 5.6 ab 33.9 a 7.5 a 14.5 b 5.2 b

5±10 12.2 a 4.8 a 7.7 a 3.8 a 13.9 a 5.2 a

19 June 0±5 50.3 a 10.3 a 34.3 a 9.7 a 27.9 a 7.8 a

5±10 18.7 a 5.6 a 18.5 a 7.0 a 36.6 a 7.6 a

17 July 0±5 14.9 a 6.2 a 20.3 a 6.6 a 14.2 a 8.5 a

5±10 13.4 a 4.9 a 14.8 a 5.9 a 14.2 a 6.7 a

10 August 0±5 5.2 b 6.5 a 9.5 a 5.8 a 7.3 ab 5.3 a

5±10 6.8 b 3.1 b 13.1 a 5.7 a 10.0 ab 4.5 a

7 October 0±5 37.4 a 8.0 a 25.1 b 6.7 a 27.1 b 6.5 a

5±10 42.4 a 6.1 a 38.3 a 7.5 a 30.6 a 6.9 a

a Mean abundance (number of individuals per sample).b Mean richness (number of family groups per sample).

The same letter following a mean for the same sample date and depth indicates there is no significant difference (p�0.05) between the tillage

treatments [by Tukey's test (SAS Institute, 1989)].

P. Neave, C.A. Fox / Applied Soil Ecology 9 (1998) 423±428 427

Acknowledgements

The authors would like to thank the following for

their assistance and advice: Dr. J. Culley, Mr. King Wu

and Dr. V . Behan-Pelletier (Agriculture and Agri-

Food Canada) and Dr. Stewart Peck (Carleton Uni-

versity, Ottawa).

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