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Despite extensive research, reduced corn (Zea mays L.) performance is still encountered using conservation tillage on fine-textured soils in cool humid temperate climates. These problems are intensified when corn is planted into residue from a previous crop such as winter wheat (Triticum aestivum L.). The objective of this 4-yr study was to determine the influence of fall zone tillage (ZT), no tillage (NT), and conventional moldboard plow tillage (CT) (fall plowing) on corn performance and soil physical quality under a winter wheat-corn-soybean (Glycine max L. Merr.) rotation with and without red clover (Trifolium pratense L.) (RC) underseeded in the wheat phase of the rotation. A randomized complete block design (3 × 2 factorial, 4 replicates) was established on three adjacent fields in the fall of 1996 on a Brookston clay loam soil (fine loamy, mixed, mesic, Typic Argiaquoll) at Woodslee, ON Canada, and measurements were collected during 1997 to 2000. Over both wet and dry growing seasons from 1998-2000, zone tillage following underseeded RC produced average corn grain yields (7.23 Mg ha-1) that were within 1% of those obtained using conventional tillage (7.33 Mg ha-1), and 36% higher than those obtained using no tillage and RC (5.33 Mg ha-1). Zone tillage also improved soil quality as evidenced by generally lower soil strength than no tillage, and near-surface soil physical quality parameters that were equivalent to, or more favorable than, those of the other treatments. It was concluded that corn production using zone tillage and RC underseeding is a viable option in Brookston clay loam soil, as it retains much of the soil quality benefit of conventional tillage but still achieves most of the yield benefit of conventional moldboard plow tillage.
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Impacts of Zone Tillage and Red Clover on Corn Performance and Soil Physical Quality
C. F. Drury,* C. S. Tan, W. D. Reynolds, T. W. Welacky, S. E. Weaver, A. S. Hamill, and T. J. Vyn
ABSTRACT benefits of conservation tillage with the yield benefits
of conventional moldboard plow tillage (e.g., Pierce et
Despite extensive research, reduced corn (Zea mays L.) perfor-
mance is still encountered using conservation tillage on fine-textured al., 1992) for cool humid climatic zones. Here, a narrow
soils in cool humid temperate climates. These problems are intensified zone 10 to 20 cm wide by 10 to 30 cm deep is convention-
when corn is planted into residue from a previous crop such as winter ally tilled in the crop row while the rest of the soil surface
wheat (Triticum aestivum L.). The objective of this 4-yr study was is left in an untouched no-till state. This supposedly
to determine the influence of fall zone tillage (ZT), no tillage (NT), encourages the more favorable soil temperature, mois-
and conventional moldboard plow tillage (CT) (fall plowing) on corn ture, aeration, density, and strength conditions associ-
performance and soil physical quality under a winter wheat–corn– ated with conventional tillage in the narrow seedbed
soybean (Glycine max L. Merr.) rotation with and without red clover
(Trifolium pratense L.) (RC) underseeded in the wheat phase of the zones, while retaining the increased erosion resistance,
rotation. A randomized complete block design (3 2 factorial, 4 organic matter protection and reduced energy inputs of
replicates) was established on three adjacent fields in the fall of 1996 no tillage between the zones. Although there is much
on a Brookston clay loam soil (fine loamy, mixed, mesic, Typic Argia- interest in the zone-till system, it has not yet been tested
quoll) at Woodslee, ON Canada, and measurements were collected extensively in cool humid temperate climates, nor on
during 1997 to 2000. Over both wet and dry growing seasons from the agriculturally important clay and clay loam soils of
1998-2000, zone tillage following underseeded RC produced average
southern Ontario. In nearby Michigan, ZT on sandy
corn grain yields (7.23 Mg ha
) that were within 1% of those obtained
using conventional tillage (7.33 Mg ha
), and 36% higher than those loam soils did indeed improve potato (Solanum tubero-
obtained using no tillage and RC (5.33 Mg ha
). Zone tillage also sum L.) yields and soil physical conditions relative to
improved soil quality as evidenced by generally lower soil strength conventional tillage in most years of a 4-yr study (Pierce
than no tillage, and near-surface soil physical quality parameters that and Burpee, 1995); however, corn yields were not in-
were equivalent to, or more favorable than, those of the other treat- creased by zone tillage in a similar 3-yr study, despite
ments. It was concluded that corn production using zone tillage and substantially reduced soil strength (penetration resis-
RC underseeding is a viable option in Brookston clay loam soil, as
it retains much of the soil quality benefit of conventional tillage but tance) within the 0- to 30-cm depth range (Pierce et
still achieves most of the yield benefit of conventional moldboard al., 1992).
plow tillage. Red clover underseeded in cereals can produce large
quantities of plant biomass and it fixes N in the nodules,
which can in turn provide the equivalent of 90 to 125
Conservation-tillage systems, such as no-till, have kg N ha
to the following crop (Bruulsema and Christie,
been demonstrated to have several advantages 1987). In addition, RC can be effective in cool-temper-
over conventional moldboard plow systems, including ate climates for increasing microbial biomass, improving
reduced soil erosion and surface runoff, slower loss of the structure of fine-textured soils (Drury et al., 1991),
soil organic matter, and lower production costs. How- and for accelerating the decomposition of surface crop
ever, there are many reports of reduced corn emergence residues (Drury et al., 1999). It was consequently hy-
and yields under no-till relative to conventional till on pothesized that including RC underseeding in a crop
fine-textured soils in humid and cool temperate cli- rotation might further improve the potential yield and
mates. This appears to be primarily a result of spring soil quality benefits of zone tillage on fine-textured soils.
soil conditions that are cooler (Graven and Carter, 1991; The objective of this study was to determine, for a
Fortin and Pierce, 1990; Fortin and Pierce, 1991) and clay loam soil in southern Ontario, if zone tillage and
wetter (Fortin, 1993) relative to conventional tillage, RC underseeding could achieve corn yields comparable
plus other factors such as increased soil bulk density with conventional moldboard plow tillage, but still re-
and strength (e.g., Hill, 1990; Pierce et al., 1992), de-
tain most of the soil quality, environmental, and reduced
creased soil air-filled porosity and saturated hydraulic
energy inputs of no tillage. To accomplish this, conven-
conductivity (e.g., Pierce et al., 1992), and desiccation
of seeds or seedlings through reopening of the planting tional moldboard plow tillage, no tillage, and zone-tillage
slot produced by the no-till planter (Drury et al., 1999). systems were applied to a winter wheat–corn–soybean
Zone tillage has been proposed as a possible alterna- rotation, with and without RC underseeded in the win-
tive tillage system that may combine the soil quality ter wheat. Evaluations were made on the basis of corn
emergence, corn yield, and near-surface soil physical
C.F. Drury, C.S. Tan, W.D. Reynolds, T.W. Welacky, S.E. Weaver, quality.
and A.S. Hamill, Greenhouse & Processing Crops Research Centre,
Agriculture and Agri-Food Canada, Harrow, ON, Canada N0R 1G0.
T.J. Vyn, Dep. of Agronomy, Purdue Univ., West Lafayette, IN 47907-
Abbreviations: CHU, corn heat unit; CT, conventional moldboard
1150. Received 22 Jan. 2002. *Corresponding author (druryc@agr.
plow tillage; FC, field capacity; NT, no tillage; PR, penetration resis-
tance; PWP, permanent wilting point; RC, red clover; WAS, wet
aggregate stability; ZT, zone tillage.Published in Soil Sci. Soc. Am. J. 67:867–877 (2003).
868 SOIL SCI. SOC. AM. J., VOL. 67, MAY–JUNE 2003
beside and 5 cm below the seed. When the corn had four
MATERIALS AND METHODS visible collors (6-leaf stage), N (28% UAN) was injected (148
Experimental Design and Agronomic Operations kgNha
) in a band 15 cm away from the row at a 10-cm depth.
All plots were sprayed with 1.8 kg ai ha
glyphosate [N-
Three adjacent fields were established in the fall of 1996 (phosphonomethyl) glycine] plus 1.0 kg ai ha
2,4-D [(2,4-
on a Brookston clay loam soil at Woodslee, ON (4213Ndichlorophenoxy) acetic acid] in the fall to kill perennial
lat., 8244W long.), so that each crop in the winter wheat– weeds, RC, and volunteer wheat. At the time of corn planting,
corn–soybean rotation would be present each year during the all plots were sprayed with 1.68 kg ai ha
pendimethalin [N-
1997-2000 study period. In the plow layer (top 15 cm), the (1-ethylpropyl)-3,4-dimethyl-2,6-dinitro benzene-amine] plus
soil has an average texture of 28% sand, 35% silt, and 37% 1.0 kg ai ha
atrazine (2-chloro-4-ethylamino-6-isopropylam-
clay, and an average organic C content of 20 g kg
(under ino-s-triazine) pre-emergence, to control newly emerging
long-term conventional tillage). The climate is humid, and weeds.
cool-temperate, with a mean annual air temperature of 8.7C,
and an average annual precipitation of 827 mm. The treat-
ments werea3by2factorial arrangement of tillage and RC Measurements
underseeded in winter wheat with four replicates. The treat-
ments included CT, ZT, and NT, each with or without red Corn Emergence and Yield
clover (RC) underseeded in the winter wheat phase of the Corn emergence was measured between four to twelve
rotation. The treatment plots were 20 m long by 9 m wide. times per week over 2 to 3 wk until all of the viable plants
Conventional tillage consisted of moldboard plowing in the emerged. Four 2-m row lengths per plot were marked with
fall to a 15-cm depth, with secondary disking and harrowing flags after planting to measure both the emergence rate and
in the following spring just before planting (May-June). Zone final crop stand. Plants were counted every 1 to 2 d within the
tillage was performed in the fall using a Trans Till (Row Tech marked areas until emergence was complete. Two subsamples
Inc. Snover, MI) single shank unit with a wavy coulter on were harvested from each plot with three rows of corn (20 m
either side of the shank to produce tilled strips that were 21 cm long) in each subsample on 6 Nov. 1997, 16 Nov. 1998, 29
wide, 15 cm deep, and spaced 75 cm apart. Corn was planted Oct. 1999, and 15 Nov. 2000 with a Gleaner combine (Allis
directly into the tilled strips in the following spring without Chamers, Millwaukee, WI). Total corn grain yields and grain
further tillage. All phases of the rotation receiving conven- moisture content were measured and yields were normalized
tional tillage are plowed in the fall every year, the treatments to 150 g kg
grain moisture content.
receiving no-till are never plowed and those receiving zone
tillage are tilled in the fall before corn and were not tilled
Surface Residue
before the soybean and winter wheat phases of the rotation.
No tillage produced no disturbance of the soil except for Surface residue weights were measured 4 to 5 times per
that caused by the no-till planter. Before the establishment growing season from 1997-2000. The residue was collected
of this study, the conventional-till and no-till plots had been from the soil surface within 20 by 76 cm metal rectangles
in place under a winter wheat–corn–soybean rotation since placed perpendicular to the corn rows with two measurements
1993. The zone-till treatment was introduced into a subset of made in every plot (n8). The residue was oven-dried at
the no-till plots in the fall of 1996. The data reported here 80C and any soil adhering to the residue was removed before
apply only to the corn phase of the rotation from 1997-2000. a dry residue mass was determined. The sampling areas were
Corn was planted (76 100 seeds ha
) in 75-cm rows for all weed-free and no living plant material was included in the
three tillage treatments using a John Deere 6-row no-till Max residue sample.
Emerge planter (Deere and Company, Moline, IL) equipped
with 45.72-cm (18-inch) ripple and bubble coulters to open Soil Moisture and Temperature
and close the planting slot, plus residue managers to improve
the seed bed. The planter was adjusted among tillage treat- Volumetric soil water content measurements were made in
ments to ensure that the same 4-cm planting depth was situ in the corn row midway between plants three times per
achieved for each tillage treatment. Planting was delayed in week at the 0- to 5- and 0- to 30-cm depths in four replicates
1997 and 2000 because of wet soil conditions resulting from of each treatment using time domain reflectometry (Topp et
high spring rainfall (Table 1). The delay was long enough in al., 1980; Topp, 1993). The 0- to 5-cm depth measurements
1997 to require an early-maturing 2950 corn heat unit (CHU) were made only during germination and early growth (from
variety (Pioneer 3752), whereas in 1998, 1999, and 2000 a planting to about the 6-leaf stage), while the 0- to 30-cm depth
normal 3250 CHU variety (NK Max 21) was used. To encour- measurements were made for the entire growing season (from
age early plant growth, liquid fertilizer (55 L ha
) was applied planting to the end of August). Soil temperature was measured
with the seed to provide 5.6 kg N ha
, 9.8 kg P ha
, and 9.3 during germination and early growth using four thermocou-
kg K ha
. Nitrogen (22 kg N ha
), P (38 kg P ha
), and K ples inserted horizontally into the undisturbed soil profile at
(37 kg K ha
) were also applied at planting in a band 5 cm 5- and 10-cm depths in two replicates of each treatment. The
temperature measurements were made continuously and inte-
Table 1. Growing season (April-August) precipitation at Woods-
grated hourly using a CR-10 micrologger.
lee, ON.
Month 1997 1998 1999 2000 30-yr Average
Soil Physical Quality Parameters
Estimates of in-row soil strength (cone penetration resis-
April 22.4 92.3 103.2 73.0 80.4
tance) were made midway between corn plants in 1998-2000
May 107.4 32.8 49.7 99.8 72.7
approximately 3 wk after corn planting, using a RIMIK CP-
June 105.6 47.2 51.7 129.6 97.4
20 cone penetrometer (Agridry Rimik, Toowoomba, Queens-
July 46.6 63.5 21.7 136.0 88.6
August 82.8 128.0 49.2 95.8 82.1
land, Australia) (cone basal area 1.2 cm
, cone angle 30,
Growing season
0–45 cm depth range, three penetrations per plot, n12).
total 364.8 363.8 275.5 534.2 421.2
During the summers of 1998-2000, intact soil cores (7.6-cm
diam. by 7.6-cm long) and grab samples were collected at the Year 1998
5.0- to 12.6-cm depth from the corn row midway between The April rainfall was 15% greater than the 30 yr
plants (n8, two cores and two grab samples per plot). The average, however rainfall in May, June, and July was
5.0- to 12.6-cm depth range was selected to reduce the near- 55, 52, and 28%, respectively below the 30-yr averages
surface artifact effects of soil cracking, but still include the
near-surface effects of the tillage and red clover treatments. for these months (Table 1). Corn in all treatments was
The cores and grab samples were used to determine dry bulk consequently stressed at the end of July; however 84 mm
density (Culley, 1993), air-filled porosity (porosity minus volu- of rain fell between August 1st and 10th with a total of
metric water content at 100 cm pressure head), plant-avail- 128 mm for August, which was 56% greater than the
able water capacity (volumetric water content at 100 cm 30-yr average rainfall.
pressure head minus volumetric water content at 15 bar The 1998 corn emergence rates were greatest under
pressure head, Topp et al., 1993), and saturated hydraulic the conventional-tillage treatments, much slower under
conductivity (Reynolds, 1993). Soil grab samples were col- the no-tillage treatments, and intermediate under the
lected from each treatment from 1997 to 2000 at a depth of zone-tillage treatments (Fig. 1). For example, after 8 d,
0- to 5-cm to determine near-surface treatment effects on wet the conventional-tillage treatments had a 56% emer-
aggregate stability (Kemper and Rosenau, 1986).
gence rate, which was significantly greater than the
zone-tillage treatments (19%), which in turn was signifi-
Statistical Analyses cantly greater than the no-tillage treatments (3%).
A 3 by 2 factorial randomized complete block design was There were no significant effects of RC on corn emer-
used with four replicates. Treatment and interaction effects gence at 8 d. Final plant stands were statistically similar
were tested for statistical significance using analysis of variance for the conventional-tillage and zone-tillage treatments
(SAS Institute, 2001). When interactions between tillage and (80–86%), whereas they were both significantly greater
red clover treatment were not significant, we also evaluated than the no-tillage treatments (52%). Corn emergence
main effect means using a least-significant-difference test rates were affected by RC in the zone-tillage treatments
(LSD) at P0.05. only, where corn emergence was faster under ZT than
under ZT RC especially between the 9th and 12th
RESULTS AND DISCUSSION day after planting.
In 1998, there were significant tillage and RC effects
Precipitation and Corn Performance on corn grain yields (Table 2). The corn grain yields for
Year 1997 the CT RC, CT, and ZT RC treatments were
similar but significantly greater than the yields for ZT,
The May and June rainfall in 1997 were 48 and 8%, NT RC, and NT (P0.1). The no tillage without
respectively, above the corresponding 30-yr averages RC underseeding (NT) and NT RC treatments had
(Table 1), which delayed corn planting until June 10. by far the lowest corn grain yields (2.64 and 3.61 Mg
The rainfall in July, on the other hand, was 47% below ha
, respectively) which were 61 to 70% lower than
the 30-yr average, while that in August was virtually the two corresponding conventional-tillage treatments
the same as the 30-yr average (Table 1). (8.92 and 9.26 Mg ha
). Red clover underseeding in-
Corn emergence in 1997 was very rapid under the creased yields by an average of 21% across the three
conventional tillage treatments, but much slower under tillages (4% for CT, 37% for NT, and 40% for ZT).
zone-tillage and no-tillage treatments (Fig. 1). By Day The 1998 corn grain yields were 5 to 60% lower than
5, 26 to 32% of the corn plants had emerged in the con- those in 1997, probably because of the 28 to 55% lower
ventional-tillage treatments but no plants had emerged rainfall in May-July relative to the corresponding 30-yr
on either the zone-tillage or no-tillage treatments. Fifty averages (Table 1). The particularly low yields for the
percent corn emergence was reached in the conven- two no-tillage treatments were probably caused at least
tional-tillage treatments by Day 6, which was signifi- partially by severe seed and seedling desiccation after
cantly greater than the emergence rates for both the pronounced reopening of the planting slots in those
zone-tillage and no-tillage treatments. Between 9 to 10 d treatments.
were required for 50% emergence in zone-tillage and
no-tillage treatments. Red clover had no significant ef- Year 1999
fect on emergence rates, except for zone tillage between
approximately Day 7 and Day 10, where corn emerged The precipitation in 1999 was above the 30-yr average
faster under ZT RC relative to ZT. Final plant stands for April, but well below the 30-yr averages in May,
were not significantly different between tillage or RC June, July, and August (Table 1). In particular, the May
treatments with emergence rates of 95% for the conven- 1 through August 31 rainfall (172.3 mm) was only about
tional-tillage treatments, 91% for the zone-tillage treat- half the 30-yr average (340.8 mm). The corn plants con-
ments, and 87% for the no-tillage treatments. sequently had a high emergence rate (Fig. 1) and initial
Despite the late planting date and slow emergence growth, but then became severely drought stressed (es-
(for the zone-tillage and no-tillage treatments), corn pecially during the grain filling period) which resulted
grain yields were high for all treatments in 1997, ranging in low grain yields for all treatments (Table 2).
from 9.1 to 9.8 Mg ha
(Table 2). There were no signifi- The 1999 corn emergence rates were rapid and very
cant tillage, RC, or tillage RC interaction effects with similar among all six treatments (Fig. 1). Final plant
stands were also high and no significant difference wasrespect to corn grain yields (Table 2).
870 SOIL SCI. SOC. AM. J., VOL. 67, MAY–JUNE 2003
Fig. 1. Corn emergence in 1997, 1998, 1999, and 2000 for the conventional tillage (CT), zone tillage (ZT), and no-tillage (NT) treatments with
and without underseeded red clover (RC). The vertical bars indicate standard error (n8).
found among treatments, with emergence being 88 to that were greater than no tillage by 21 and 25%, respec-
91% for the two conventional-tillage treatments, 94 to tively.
95% for the two no-tillage treatments, and 91 to 93%
for the two zone-tillage treatments. We believe this oc- Year 2000
curred because 26.5 mm of rain fell during the 3 d after
The 2000 growing season was very wet, exceeding the
planting (21–23 May 1999), and because the planter slot
monthly and cumulative 30-yr averages by substantial
did not reopen in the two no-tillage treatments, as it
margins (Table 1). As a result, corn planting was delayed
had in 1997 and 1998.
by wet soil conditions until June 2. Corn emergence
Corn grain yields in 1999 were similar for the conven-
rates were rapid, although slower for the two no-tillage
tional-tillage and zone-tillage treatments (4.4–4.7 Mg
treatments relative to the other treatments (Fig. 1). For
), but lower for the no-tillage treatments (3.7 Mg
example, after 8 d, conventional-tillage treatments had
), which resulted in a significant tillage effect
58% emergence, which was significantly greater than
(Table 2). Red clover underseeded in the previous win-
the zone-tillage treatments (44%), and the zone-tillage
ter wheat crop did not improve corn grain yields in 1999,
treatments had significantly greater emergence than no-
and no significant interactions between RC and tillage
tillage treatments (11%). Red clover did not affect
occurred. Averaged over the RC treatments, conven-
tional tillage and zone tillage produced corn grain yields emergence in 2000. Final plant stands were nonetheless
Table 2. Corn grain yields on a Brookston clay loam soil under conventional tillage (CT), zone tillage (ZT), and no-tillage (NT) with
and without red clover (RC) underseeded into the winter wheat phase of a wheat–corn–soybean rotation.
Treatment 1997 1998 1999 2000 Mean
Yield (Mg ha
CT 9.76 (0.26)‡ 8.92 (0.66) 4.55 (0.48) 8.52 (0.23) 7.33 (0.37)
CT RC 9.74 (0.38) 9.26 (0.54) 4.38 (0.50) 9.02 (0.31) 7.55 (0.46)
ZT 9.30 (0.42) 5.76 (0.92) 4.58 (0.70) 8.25 (0.29) 6.20 (0.50)
ZT RC 9.84 (0.24) 8.09 (0.24) 4.68 (0.34) 8.96 (0.48) 7.23 (0.20)
NT† 2.64 (0.53) 3.74 (0.27) 8.61 (0.61) 5.00 (0.04)
NT RC 9.12 (0.27) 3.61 (0.87) 3.67 (0.57) 8.70 (0.29) 5.33 (0.62)
F statistics
Tillage 2.58 62.2*** 3.74* 0.1 28.4***
Red Clover 1.02 7.6** 0.03 1.6 4.4*
Tillage Red Clover 1.18 1.8 0.07 0.3 1.0
The NT treatment without red clover was initiated in the wheat crop in 1997. Therefore 1998 is the first year of NT without RC for the corn crop. Since
there was a treatment missing in 1997, the overall average reported is for the yields from 1998 to 2000.
Numbers in parenthesis are standard error (n4).
* Significant at the 0.05 probability level.
** Significant at the 0.01 probability level.
*** Significant at the 0.001 probability level.
uniformly high for all treatments (90%), and no signif- across years (Fig. 2). Residue cover over the two conven-
icant tillage or RC effects were evident. tional tillage treatments varied from highs of 0.1 to 1.8
Corn grain yields were substantial and fairly uniform Mg ha
in the spring to lows of 0.2 Mg ha
in the
in 2000, ranging from a low of 8.25 Mg ha
for ZT to fall. Surface residue over the four conservational-tillage
a high of 9.02 Mg ha
for CT RC, with no significant treatments, on the other hand, ranged from highs of 2.6
tillage, RC or tillage by RC interaction effects (Table 2). to 7.4 Mg ha
in the spring, to lows of 0.9 to 3.1 Mg
in the fall. Note that 1999 was an exception in
that residue covers did not decline appreciably over
Comparison of Average Corn Yields the growing season for any of the treatments. This was
The treatments were compared using corn grain yields attributed to the very dry 1999 growing season (Table 1),
averaged over 1998, 1999, and 2000 (Table 2). The 1997 which undoubtedly limited biological decomposition on
yields were excluded from the comparison because the the soil surface. In October 1997, 1998, and 2000, ZT
NT treatment was missing for that year. There was a RC had, respectively, 33, 49, and 31% less residue cover
highly significant tillage effect (P0.001) and a signifi- than ZT; and in 1998 and 2000, NT RC had 35% less
cant RC effect (P0.05) and the interaction between residue cover than NT (Fig. 2). Red clover has a low
tillage and RC treatment was not significant (Table 2). C/N ratio as a result of symbiotic N fixation and it also
Averaged over the RC treatments, the 3-yr average of has a considerable amount of soluble C, which has been
the corn grain yields from 1998-2000 were significantly found to stimulate biological activity (McKenney et al.,
greater (P0.001) for the conventional-tillage treat- 1993). Hence, it is readily decomposed by soil microor-
ments (7.44 Mg ha
), than the zone-tillage treatments ganisms, which leads to an increase in soil ammonium
(6.71 Mg ha
), which was in turn significantly greater through mineralization. In contrast wheat straw residue
than the corn grain yields for the no-tillage treatments has a high C/N ratio and its decomposition is limited
(5.17 Mg ha
). Averaged over tillage treatments, in- by available N. Hence the additional supply of inorganic
cluding RC in the rotation resulted in significantly (PN from RC decomposition probably contributed to the
0.05) greater corn grain yields (6.70 Mg ha
) than treat- decomposition of wheat straw, which was underseeded
ments without RC (6.18 Mg ha
). Although the conven- to RC. The accelerated decomposition of wheat residues
tional-tillage treatments produced the greatest average by including RC in the rotation, was observed previously
yields, the ZT RC yield was only 4% lower than by Drury et al. (1999).
CT RC and only 1% lower than CT. The average
NT RC yield, on the other hand, was 29% lower than
Soil Temperature and Water Content
CT RC and 27% lower than CT. Red clover resulted
in an average yield increase of 9% across all tillages; During the emergence and early growth periods of
and was especially effective for zone tillage, producing 1997-1999, the two conventional-tillage treatments had
an average yield increase of 17% relative to no RC. slightly greater average soil temperatures at the 5- and
Consequently, ZT RC appears capable, on average, 10-cm depths than the other treatments (Table 3). There
of producing corn yields, which are competitive with was also a tendency during those years (notwithstanding
those from CT on a Brookston clay loam soil under a a few exceptions) for the two no-tillage treatments to
winter wheat–corn–soybean rotation. have the lowest temperatures, and for the two zone-
tillage treatments to have intermediate temperatures
Surface Crop Residue relative to the conventional-tillage treatments. There
was little difference among any of the average soil tem-
As expected, crop residue on the soil surface varied
substantially with tillage treatment, time of year and peratures in 2000, although CT clearly had the greatest
872 SOIL SCI. SOC. AM. J., VOL. 67, MAY–JUNE 2003
Fig. 2. Surface residue cover in 1997, 1998, 1999, and 2000 for the conventional tillage (CT), zone tillage (ZT), and no-tillage (NT) treatments
with and without underseeded red clover (RC). The vertical bars indicate standard error (n8).
soil temperature at the 10-cm depth, while both CT and 0- to 30-cm depth, on the other hand, there was a ten-
dency (albeit not entirely consistent) for average soilNT had the greatest temperatures at the 5-cm depth. It
was also noted that RC underseeding had no apparent water content to change with tillage, that is, the two
conventional-tillage treatments yielded the lowest val-effect on average soil temperature, except in 2000 where
RC underseeding tended to produce slightly lower aver- ues, the two zone-tillage treatments generally yielded
intermediate values, and the two no-tillage treatmentsage temperatures at the 5-cm depth (especially for NT
RC). Given that the average soil temperatures were all usually yielded the highest values. The average soil wa-
ter contents at the 0- to 5-cm depth were very low inabove 20C, it is unlikely that temperature contributed
in any major way to the highly variable corn emergence 1998 and 1999 for all treatments, which is consistent
with the very low May and June rainfall during thosepatterns and plant stands observed among treatments
(in 1997 and 1998) and among years (Fig. 1). years (Table 1). By the same token, the relatively high
average water contents for all treatments at the 0- toAverage soil water content at the 0- to 5-cm depth
was slightly lower under CT and CT RC in most 5-cm depth in 2000 reflect the high May and June rainfall
for that year (Table 1). As expected, the average wateryears, but no trends or patterns in water content were
evident among the other treatments (Table 3). At the contents at the 0- to 30-cm depth were generally much
Table 3. Average soil temperature and volumetric water content (m
) in a Brookston clay loam soil under conventional tillage (CT),
zone tillage (ZT), and no-tillage (NT) with and without red clover (RC) underseeded into the winter wheat phase of a wheat–corn–
soybean rotation. Measurements were taken in the corn phase.
Temperature, C Water Content, m
Treatment 5 cm depth† 10 cm depth† 0–5 cm depth† 0–30 cm depth‡
CT 24.5 (0.2)§ 24.2 (0.1) 0.228 (0.025) 0.266 (0.026)
CT RC 24.8 (0.2) 24.5 (0.2) 0.221 (0.025) 0.258 (0.018)
ZT 23.9 (0.2) 23.6 (0.2) 0.244 (0.024) 0.272 (0.010)
ZT RC 23.8 (0.2) 23.5 (0.2) 0.245 (0.022) 0.272 (0.008)
NT –¶
NT RC 24.1 (0.2) 23.5 (0.2) 0.238 (0.015) 0.288 (0.011)
CT 21.2 (0.1) 20.9 (0.1) 0.129 (0.009) 0.232 (0.009)
CT RC 21.0 (0.2) 20.8 (0.1) 0.132 (0.017) 0.231 (0.009)
ZT 20.5 (0.2) 20.1 (0.1) 0.168 (0.013) 0.249 (0.008)
ZT RC 20.4 (0.1) 20.0 (0.1) 0.151 (0.015) 0.241 (0.008)
NT 20.3 (0.2) 19.9 (0.1) 0.148 (0.012) 0.256 (0.006)
NT RC 20.7 (0.1) 20.3 (0.1) 0.148 (0.011) 0.266 (0.008)
CT 25.0 (0.2) 24.7 (0.2) 0.155 (0.014) 0.174 (0.010)
CT RC 25.1 (0.2) 24.6 (0.2) 0.175 (0.017) 0.208 (0.012)
ZT 23.9 (0.2) 23.5 (0.1) 0.170 (0.015) 0.212 (0.008)
ZT RC 23.7 (0.2) 23.3 (0.2) 0.193 (0.014) 0.244 (0.011)
NT 23.1 (0.3) 22.9 (0.2) 0.157 (0.014) 0.230 (0.009)
NT RC 23.2 (0.2) 22.8 (0.1) 0.199 (0.015) 0.251 (0.010)
CT 22.3 (0.5) 22.2 (0.5) 0.272 (0.025) 0.315 (0.025)
CT RC 21.9 (0.5) 21.4 (0.6) 0.306 (0.030) 0.318 (0.026)
ZT 21.7 (0.2) 21.5 (0.4) 0.288 (0.024) 0.338 (0.021)
ZT RC 21.5 (0.4) 21.5 (0.4) 0.299 (0.028) 0.325 (0.005)
NT 22.5 (0.6) 21.5 (0.8) 0.303 (0.023) 0.368 (0.011)
NT RC 21.2 (0.4) 21.5 (0.3) 0.298 (0.013) 0.354 (0.013)
F Statistics
1998 Tillage 31.0*** 19.0*** 20.7*** 17.1***
RC 0.2 0.1 4.7* 0.1
Tillage RC 6.1** 2.4 3.8* 1.6
1999 Tillage 123.8*** 108.8*** 6.7** 39.8***
RC 0.1 3.7 52.4*** 32.6***
Tillage RC 1.2 0.1 3.3 0.6
2000 Tillage 3.5* 0.8 0.3 4.8*
RC 18.2** 2.1 1.1 0.4
Tillage RC 3.9* 0.9 0.8 0.2
Arithmetic average values for the time period from planting to the 6-leaf growth stage.
Arithmetic average values for the time period from planting to the end of the growing season (August).
§ Bracketed values are standard error (n4).
Treatment not established until 1998.
* Significant at the 0.05 probability level.
** Significant at the 0.01 probability level.
*** Significant at the 0.001 probability level.
greater than at the 0- to 5-cm depth, and the year- moderate to high corn yields for those years (Table 2). In
1998 and 1999, however, the average soil water contentsto-year variation in water content followed the same
general pattern as that of the 0- to 5-cm depth. It was were at or below the PWP limits (Table 3), which is
again consistent with the moderate to very low cornnoted that RC underseeding had a significant effect
on average soil water content over the depth ranges yields for those years (Table 2).
investigated in 1999. In all the tillage treatments, RC
underseeding had greater soil water content relative to Soil Physical Quality
no RC. Cone Penetration Resistance
Many field crops tend to perform best when average
root-zone water contents fall within a range defined at The variability and overall shapes of the cone penetra-
the wet end by the soil’s field capacity (FC) water con- tion resistance profiles changed substantially between
tent and at the dry end by the soil’s permanent-wilting 1998, 1999, and 2000 (Fig. 3). This most likely occurred
point (PWP) water content (Kramer, 1969). The depth- because cone penetrometer measurements can be very
averaged FC and PWP water contents for the soil were sensitive to small changes in soil bulk density, water
0.36 and 0.25 m
, respectively, over the 0- to 5-cm content, texture, organic C content, and structure (e.g.,
depth, and 0.32 and 0.20 m
, respectively, over the Bengough et al., 2001). Among-year variability may also
0- to 30-cm depth. Average water contents at 0 to 5 cm have been exacerbated by the fact that each year’s mea-
and 0 to 30 cm were within the FC and PWP limits in surements corresponded to a different (although adja-
cent) field. Itis unlikely, however, thatsoil water content1997 and 2000 (Table 3), and this is consistent with the
874 SOIL SCI. SOC. AM. J., VOL. 67, MAY–JUNE 2003
Fig. 3. Mean penetration resistance in 1998, 1999, and 2000 for the conventional tillage (CT), zone tillage (ZT) and no-tillage (NT) treatments
with and without underseeded red clover (RC). The horizontal bars indicate LSD value at P0.05 (n12).
contributed substantially to among-treatment variability patterns are consistent with the above PR results in
that greater average PR in the 0- to 30-cm depth rangewithin each year (or field) because water content differ-
ences were small at the time of the penetrometer mea- corresponds with lower yields (Table 2).
In 1999, both tillage and RC effects were evident,surements, and water content did not correlate with
penetration resistance (PR) (data not shown). with tillage having a far greater effect than RC (Fig. 3).
Over approximately the 5- to 25-cm depth, the two no-In 1998, a tillage effect on cone PR was clearly evident
over about the 5- to 30-cm depth, with the two no-tillage tillage treatments produced the greatest PR values, with
NT RC producing slightly greater values than NT.treatments yielding the greatest PR values followed by
the two zone-tillage treatments and then the two con- From about 5 to 13 cm, the two conventional-tillage
treatments produced greater PR values than the twoventional-tillage treatments (Fig. 3). A RC effect was
evident only for no-tillage, with NT RC yielding zone-tillage treatments, while from about 20 to 30 cm
the two zone-tillage treatments produced greater valuesgreater PR values over the 5- to 30-cm depth than NT.
Bengough and Mullins (1991) suggested that the growth than the two conventional-tillage treatments. It is also
interesting to note that the small effects of RC on PRrate of corn seedling roots in sandy loam soils decrease
linearly with increasing PR, resulting in a 50% reduction were reversed for conventional tillage relative to the
other tillages within the 5- to 13-cm depth range. Allat PR approximately 2000 kPa. Comparable results were
reported in Bennie (1996), where it is showed that 70 d six treatments reached or exceeded the PR 2000 kPa
value where root growth may be reduced by 50%growth in lysimeters at PR 2000 kPa produces about
a 66% reduction in corn root length relative to uncom- because of excessive soil strength (Bennie, 1996; Ben-
gough and Mullins, 1991). This was likely because ofpacted controls (PR ~ 500 kPa). Our corn grain yield
the very dry soil conditionsboth throughout the growing they had the greatest strengths during a normal rainfall
year (1998), and excessive strengths in a low rainfall yearseason (Table 3) and at the time of the penetrometer
measurements (datanot shown).Note that the generally (1999). Red clover did not have important or consistent
effects on soil strength under any of the tillage treat-high average PR values correspond to the substantially
lower 1999 corn grain yields for all treatments (Table 2). ments in any of the 3 yr (Fig. 3). As mentioned above,
corn grain yield tended to be negatively correlated withThe PR profiles further indicate that the average soil
mechanical resistance to crop root growth in the top average soil strength, in that lower average PR corre-
sponded with greater yield.20 cm of soil was lowest under the two zone-tillage
treatments, greatest under the two no-tillage treatments,
and intermediate under the two conventional-tillage Additional Soil Parameters
treatments. As in the previous year, these average PR Bulk density ranged from a high of 1.48 Mg m
values correlate with yield in that corn grain yield was RC, 2000) to a low of 1.28 Mg m
(ZT RC, 2000)
the greatest under the zone-tillage treatments (albeit by (Table 4). Significant tillage effects occurred in all 3
a small margin), intermediate under the conventional yr, and significant RC and tillage by clover interaction
tillage-treatments, and lowest under the no-tillage treat- effects occurred in 2000. The optimal bulk density for
ments (Table 2). root growth in fine-textured soils is on the order of 0.8
In 2000, the PR values were generally much lower to 1.2 Mg m
(e.g., Olness et al., 1998, Reynolds et al.,
than in 1998 and 1999 (Fig. 3). In addition, PR increased 2002), and root growth often stops completely in clayey
approximately linearly with increasing depth for all soils at about 1.5 Mg m
(Veihmeyer and Hendrickson,
treatments, ranging from near zero close to the soil 1948). Consequently, corn root growth was likely to
surface to 1600 to 2200 kPa at 45-cm depth, with no have been somewhat impeded by high soil density for
substantial differences among treatments. These results all six treatments, and especially under the CT RC
are most likely the result of the substantially greater treatment in 2000. The ZT RC treatment had either
precipitation (Table 1) and soil profile moisture con- the lowest, or among the lowest, bulk density in each
tents (Table 3) throughout the 2000 growing season, of the 3 yr, while the two no-tillage treatments often
relative to the 1998 and 1999 growing seasons. The slight had the greatest bulk density. This pattern is generally
but sudden divergence of the CT, CT RC, and ZT consistent with the soil strength (Fig. 3) and corn yield
profiles at about the 18-cm depth (Fig. 3) is currently (Table 2) patterns mentioned earlier.
unexplained, but may be related in some way to tillage The air-filled porosities ranged from 0.14 to 0.20
operations in the previous fall (1999), which was much m
, with significant tillage and tillage by clover inter-
wetter than average. The lack of difference in average action effects in 1999 (Table 4). These values are, for
PR over the 0- to 20-cm depth is consistent with the the most part, near or above the suggested minimum
lack of difference among corn grain yields (Table 2). of 0.15 m
for adequate near-surface aeration in the
Comparing the 1998-2000 PR results, it appears that root-zone of clayey soils (Cockroft and Olsson, 1997).
the two zone-tillage treatments produced the lowest Significant or frequent near-surface aeration deficits are
overall soil strengths (i.e., lowest PR values) in a low therefore unlikely in any of the six treatments, and no
rainfall year (1999), and intermediate overall strengths among-treatment patterns were evident.
in a normal rainfall year (1998). Zone tillage was also Plant-available water capacity tended to be low, rang-
found to decrease soil strength relative to conventional ing from 0.089 m
(NT, 1998) to 0.142 m
tillage in loam soils cropped to potatoes (Pierce and
RC and NT, 2000), with no significant RC effects but
Burpee, 1995) and corn (Pierce et al., 1992). The two
significant tillage effects in 1998 and 1999 (Table 4).
no-tillage treatments tended to produce the greatest
The low values occurred despite large FC water contents
overall soil strengths in the normal and low rainfall years
(0.31–0.34 m
) because the PWP water contents
(1998 and 1999, respectively), while the two conven-
were also large (0.18–0.23 m
). It has been proposed
tional-tillage treatments produced the lowest overall soil
that plant-available water capacities greater than 0.20
strengths under normal rainfall (1998) and intermediate
are required in fine-textured soils for optimal
strengths under low rainfall (1999). Under high soil
root growth, function, and minimum droughtiness
moisture conditions (2000), there were no substantial
(Cockroft and Olsson, 1997). Consequently, crops
differences in soil strength among any of the treatments.
grown on all six treatments may be prone to periodic
Given the treatment differences in PR often decrease
with increasing soil moisture (Bengough et al., 2001), drought stress, even when the soil is still relatively moist
(i.e., water contents as high as 0.23 m
). No among-this result suggests that high soil moisture can override
tillage effects on soil strength in Brookston clay loam. treatment patterns were evident.
Saturated hydraulic conductivity (K
) ranged from aFor the 3-yr period, it appears that the two zone-tillage
treatments had the most favorable overall soil strength low of 4.2 10
cm s
(CT RC, 2000) to a high of
2.9 10
cm s
(ZT, 1999), with significant tillageprofiles, as they maintained lower soil strengths than the
other treatments during a dry year (1999), reasonable effects in 1998 and 2000, but no significant RC effects
(Table 4). No distinct patterns were evident, althoughstrengths during a normal rainfall year (1998), and simi-
lar strengths to the other treatments during a wet year the average K
in 1999 was greater than in 1998 or 2000,
which corresponded with greater soil surface cracking(2000). The two no-tillage treatments, on the other
hand, had the least favorable soil strength profiles, as observed in 1999 owing to very dry soil conditions
876 SOIL SCI. SOC. AM. J., VOL. 67, MAY–JUNE 2003
Table 4. Bulk density, air-filled porosity, plant-available water capacity, and saturated hydraulic conductivity (K
) in a Brookston clay
loam soil under conventional tillage (CT), zone tillage (ZT), and no-tillage (NT) with and without red clover (RC) underseeded into
the winter wheat phase of a wheat–corn–soybean rotation. Measurements taken in the corn phase.
Bulk Air-Filled Plant-Available
Treatment Density Porosity Water Capacity K
Mg m
cm s
CT 1.41 (0.03)† 0.172 (0.02) 0.108 (0.01) 3.01E-02 (3.66)
CT RC 1.36 (0.02) 0.176 (0.02) 0.100 (0.01) 5.80E-02 (2.87)
ZT 1.31 (0.02) 0.196 (0.02) 0.109 (0.01) 1.25E-01 (1.92)
ZT RC 1.29 (0.02) 0.202 (0.02) 0.110 (0.01) 1.61E-01 (2.33)
NT 1.41 (0.02) 0.199 (0.02) 0.089 (0.01) 1.03E-01 (1.58)
NT RC 1.44 (0.02) 0.176 (0.01) 0.094 (0.01) 5.34E-02 (1.42)
CT 1.30 (0.03) 0.170 (0.01) 0.128 (0.01) 1.91E-01 (2.93)
CT RC 1.36 (0.04) 0.185 (0.01) 0.124 (0.01) 2.56E-01 (1.90)
ZT 1.30 (0.04) 0.175 (0.01) 0.127 (0.01) 2.86E-01 (2.15)
ZT RC 1.38 (0.04) 0.135 (0.01) 0.137 (0.02) 1.14E-01 (4.53)
NT 1.42 (0.03) 0.140 (0.01) 0.111 (0.01) 1.34E-01 (2.71)
NT RC 1.39 (0.04) 0.136 (0.01) 0.097 (0.01) 1.33E-01 (5.72)
CT 1.35 (0.03) 0.189 (0.01) 0.137 (0.01) 1.46E-03 (5.47)
CT RC 1.48 (0.02) 0.154 (0.01) 0.133 (0.01) 4.23E-04 (11.53)
ZT 1.30 (0.03) 0.178 (0.01) 0.136 (0.01) 1.45E-01 (6.72)
ZT RC 1.28 (0.04) 0.182 (0.02) 0.142 (0.01) 1.12E-01 (4.37)
NT 1.29 (0.02) 0.166 (0.01) 0.142 (0.01) 1.31E-01 (2.97)
NT RC 1.35 (0.02) 0.169 (0.02) 0.116 (0.01) 3.16E-02 (3.85)
F Statistics
1998 Tillage 14.62*** 1.23 4.87* 8.03**
RC 0.89 0.11 0.04 0.11
Tillage RC 1.29 0.49 0.65 2.44
1999 Tillage 5.22** 10.60*** 4.19* 0.71
RC 3.87 1.89 0.08 0.37
Tillage RC 2.79 5.25** 0.70 1.09
2000 Tillage 13.86*** 0.40 0.52 35.41***
RC 13.92*** 2.54 0.54 2.30
Tillage RC 4.57* 1.21 1.48 0.46
Bracketed values are standard error, except for hydraulic conductivity where the bracketed values are standard error factor (multiplier/divisor about
geometric mean hydraulic conductivity) (n8).
* Significant at the 0.05 probability level.
** Significant at the 0.01 probability level.
*** Significant at the 0.001 probability level.
(Table 3). Saturated hydraulic conductivity values in the Overall Treatment Effects on Soil Physical Quality
range, 10
to 10
cm s
, may provide an optimum Generally speaking, the six treatments did not have
between the competing needs for rapid sorption into large or consistent effects on the measured soil physical
the soil matrix of needed crop-available water, and rapid quality parameters during 1998, 1999, and 2000. How-
drainage of excess water that could cause water-logging ever, there was a tendency (albeit not entirely consistent
and associated aeration deficits (Topp et al., 1997). All or always statistically significant) for ZT RC to have
treatments exceeded this range, except for the two con- near-surface parameter values that were equivalent to
ventional-tillage treatments in 2000. Thus all treatments or somewhat more favorable than those of the other
tended to be prone to near-surface droughtiness because treatments (Table 4, Fig. 3 and 4). This implies as a
infiltration and drainage in the near-surface soil may be consequence that the near surface soil physical quality
too rapid to allow adequate sorption of crop-available under ZT RC tended to be equivalent to, or slightly
water into the soil matrix. On the other hand, problems more favorable than, the soil physical quality under the
associated with near-surface water logging, erosion, and other treatments.
runoff are less likely.
Wet aggregate stability (WAS) was not consistently
affected by tillage or RC (Fig. 4). The WAS values were CONCLUSIONS
of similar magnitude (60%) among treatments and Tillage and RC underseeding were compared on a
years, except for the two conventional-tillage treatments clay loam soil in southern Ontario in terms of corn
in 1997 and 2000 where WAS 30%. Generally speak- performance and soil physical quality. The tillage treat-
ing, RC increased the WAS slightly, however, this in- ments included fall zone tillage, no tillage, and conven-
crease was not always significant, and exceptions oc- tional tillage using fall moldboard plowing. The crop-
curred under conventional tillage in 1997 and 1998 and
ping system was a winter wheat–corn–soybean rotation,
under no-tillage in 2000 where the RC treatment pro-
with and without RC underseeding in the winter wheat
duced a slight decrease. The reasons for these exceptions
phase. Fall zone tillage with RC underseeding produced
are currently unknown. In three of the 4 yr the ZT
the greatest, or among the greatest, corn grain yields in
RC and NT RC treatments had greater WAS than
the two conventional-tillage treatments. every year of the study, which included both wet and
Bengough, A.G., and C.E. Mullins. 1991. Penetrometer resistance,
root penetration and root elongation rate in two sandy loam soils.
Plant Soil 131:59–66.
Bennie, A.T.P. 1996. Growth and mechanical impedance. p. 453–470.
In Y. Waisel et al. (ed.) Plant roots: The hidden half (2nd ed.).
Marcel Dekker Inc., New York.
Bruulsema, T.W., and B.R. Christie. 1987. Nitrogen contribution to
succeeding corn from alfalfa and red clover. Agron. J. 79:96–100.
Cockroft, B., and K.A. Olsson. 1997. Case study of soil quality in
south-eastern Australia: Management of structure for roots in du-
plex soils. p. 339–350. In E.G. Gregorich and M.R. Carter (ed.)
Soil quality for crop production and ecosystem health. Elsevier,
New York.
Culley, J.L.B. 1993. Density and compressibility. p. 529–539. In M.R.
Carter (ed.) Soil sampling and methods of analysis. Canadian Soci-
ety of Soil Science, Lewis Publishers, Boca Raton, FL.
Drury, C.F., J.A. Stone, and W.I. Findlay. 1991. Microbial biomass
and soil structure associated with corn, grasses, and legumes. Soil
Sci. Soc. Am. J. 55:805–811.
Drury, C.F., C.S. Tan, T.W. Welacky, T.O. Oloya, A.S. Hamill, and
S.E. Weaver. 1999. Red clover and tillage influence soil tempera-
ture, moisture, and corn emergence. Agron. J. 91:101–108.
Fortin, M.-C. 1993. Soil temperature, soil water, and no-till corn devel-
opment following in-row residue removal. Agron. J. 85:571–576.
Fortin, M.-C., and F.J. Pierce. 1990. Developmental and growth effects
of crop residues on corn. Agron. J. 82:710–715.
Fortin, M.-C., and F.J. Pierce. 1991. Timing and nature of mulch
retardation of corn vegetative development. Agron. J. 83:258–263.
Graven, L.M., and P.R. Carter. 1991. Seed quality effect on corn
performance under conventional and no-tillage systems. J. Prod.
Agric. 4:366–373.
Hill, R.L. 1990. Long-term conventional and no-tillage effects on
selected soil physical properties. Soil Sci. Soc. Am. J. 54:161–166.
Kemper, W.D., and R.C. Rosenau. 1986. Aggregate stability and size
distribution. p. 425–442. In A. Klute (ed.) Methods of soil analysis.
Fig. 4. Wet aggregate stability (WAS) at 0-5 cm depth in 1997, 1998, Part 1. 2nd ed. Agron. Mongr. No. 9. SSSA, Madison, WI.
1999, and 2000 for the conventional tillage (CT), zone tillage (ZT) Kramer, P.J. 1969. Plant and water relationships: A Modern synthesis.
and no-tillage (NT) treatments with and without underseeded red McGraw-Hill, New York.
clover (RC). The vertical bars indicate standard error (n4). McKenney, D.J., S.W. Wang, C.F. Drury, and W.I Findlay. 1993.
Denitrification and mineralization in soil amended with legume,
dry growing seasons. No tillage, on the other hand, often grass and corn residues. Soil Sci. Soc. Am. J. 57:1013–1020.
Olness, A., C.E. Clapp, R. Liu, and A.J. Palazzo. 1998. Biosolids and
produced the lowest, or among the lowest, corn grain their effects on soil properties. p. 141–165. In A. Wallace and R.E.
yields. Zone tillage with underseeded RC also tended Terry (ed.) Handbook of Soil Conditioners. Marcel Dekker, Inc.,
to produce soil strength profiles and near-surface soil New York.
physical quality that were equivalent to, or slightly more Pierce, F.J., and C.G. Burpee. 1995. Zone tillage effects on soil proper-
ties and yield and quality of potatoes (Solanum tuberosum L.). Soil
favorable than, those of the other treatments. Fall zone Tillage Res. 35:135–146.
tillage with RC underseeding thus appears viable for Pierce, F.J., M.-C. Fortin, and M.J. Staton. 1992. Immediate and resid-
corn production in a wheat–corn–soybean rotation on ual effects of zone tillage in rotation with no-tillage on soil physical
fine-textured soils in southern Ontario, as it maintains properties and corn performance. Soil Tillage Res. 24:149–165.
Reynolds, W.D. 1993. Saturated hydraulic conductivity: Laboratory
much of the soil quality benefits of conservational tillage measurement. p. 589–598. In M. R. Carter (ed.) Soil sampling
while retaining much of the yield benefit of conventional and methods of analysis. Canadian Society of Soil Science, Lewis
moldboard plow tillage. Publishers, Boca Raton, FL.
Reynolds, W.D., B.T. Bowman, C.F. Drury, C.S. Tan, and X. Lu.
2002. Indicators of good soil physical quality: Density and storage
ACKNOWLEDGMENTS parameters. Geoderma 110:131–146.
We gratefully acknowledge the Ontario Corn Producers SAS Institute. 2001. SAS System for Windows. V8. SAS Institute Inc.,
Association, the Canadian Adaptation Council (CanAdapt) Cary, NC.
Topp, G.C. 1993. Soil water content. p. 541–557. In M. R. Carter (ed.)
and the Matching Investment Initiative (MII) program of Soil sampling and methods of analysis. Canadian Society of Soil
Agriculture and Agri-Food Canada for providing financial Science, Lewis Publishers, Boca Raton, FL.
support for this research. We also acknowledge Tom Oloya, Topp, G.C., J.L. Davis, and A.P. Annan. 1980. Electromagnetic deter-
Vic Bernyk, Wayne Calder, Karl Rinas, George Stasko, Joann mination of soil water content: measurement in coaxial transmis-
Gignac, Don Pohlman, Mac Whaley, Scott Mannell, Mike sion lines. Water Resour. Res. 16:574–582.
Bissonnette, and Arpad Szabo for their valuable technical as- Topp, G.C., Y.T. Galganov, B.C. Ball, and M.R. Carter. 1993. Soil
sistance. water desorption curves. p. 569–579. In M. R. Carter (ed.) Soil
Sampling and Methods of Analysis. Canadian Society of Soil Sci-
ence, Lewis Publishers, Boca Raton, FL.
REFERENCES Topp, G.C., W.D. Reynolds, F.J. Cooke, J.M. Kirby, and M.R. Carter.
Bengough, A.G., D.J. Campbell, and M.F. O’Sullivan. 2001. Pene- 1997. Physical attributes of soil quality. p. 21–58. In E.G. Gregorich
trometer techniques in relation to soil compaction and root growth. and M.R. Carter (ed.) Soil quality for crop production and ecosys-
p. 377–403. In K.A. Smith and C.E. Mullins (ed.) Soil and environ- tem health. Elsevier, New York.
mental analysis: Physical methods (2nd ed.). Marcel Dekker Inc., Veihmeyer, F.J., and A.H. Hendrickson. 1948. Soil density and root
penetration. Soil Sci. 65:487–493.New York.
... It is well documented that adding a cover crop to a cropping system can sequester organic carbon (Blanco-Canqui et al., 2013;Stavi, Lal, Jones, & Reeder, 2012), increase soil microbial enzyme activity (Chavarría et al., 2016;McDaniel & Grandy, 2016;Mullen, Melhorn, Tyler, & Duck, 1998) (Drury et al., 2003;Keisling, Scott, Waddle, Williams, & Frans, 1994), porosity, saturated hydraulic conductivity, and water retention (Keisling et al., 1994). Cover crops have also been reported to increase cropping system yields through their ability to conserve soil water, supress weeds, and increase soil N supply through biological N 2 fixing and nutrient cycling (Andraski & Bundy, 2005;Kuo & Jellum, 2000;Miguez & Bollero, 2005). ...
... The increase in soil organic matter suggests that red clover improves soil health by increasing the input of high-quality residue (narrow C to N ratios) to the soil. The increased soil organic matter could further increase soil aggregation which will reduce the susceptibility of the soil to erosion (Ruis et al., 2017), Furthermore, other Ontario studies show that corn and soybean yields increase when a red clover cover crop is underseeded in winter wheat in a corn-soybean rotation (Drury et al., 1999(Drury et al., , 2003Gaudin et al., 2015). The yield increases were attributed to the ability of red clover to provide additional plant-available nitrogen and by increasing the decomposition rate of wheat straw. ...
... Although not found in this study, higher concentrations of plant available soil N usually occur when red clover is underseeded to winter wheat, which has been attributed to the ability of red clover to enhance decomposition of wheat straw (e.g. Drury et al., 2003;Gaudin et al., 2015). Soil respiration T A B L E 2 Statistical analyses of the effects of rotation and red clover on soil pH (pH), available soil test phosphorus (STP) and extractable potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), zinc (Zn), manganese (Mn), boron (B) and copper (Cu) a WW, monoculture winter wheat; WW-S, winter wheat-soybean; C-S-WW, corn-soybean-winter wheat; WW-S-S, winter wheat-soybean-soybean. ...
Demand for food is rising and the ability of any particular soil to support sustainable food production is dependent upon a variety of soil biochemical, chemical and physical soil parameters. However, the challenge is that the impacts of a new management practice on soil properties may take years to assess. In this field study, we investigated the effects of long‐term cropping rotation treatments (established in 2001) on soil health indicators from soils under monoculture, 2‐yr and 3‐yr crop rotations with and without a cover crop. In particular, we compared soil heath indicators under eight cropping sequences including continuous winter wheat (Triticum aestivum L.) (WW), soybean (Glycine max L.)–winter wheat (S–WW), corn (Zea mays L.)–soybean–winter wheat (C–S–WW), and winter wheat–soybean–soybean (WW–S–S) all with and without red clover (Trifolium pretense L.) (RC) in the wheat phase of the rotation. We measured ten soil health indicators collected from the wheat phase of the rotation. Crop rotation had greater effects on soil health indicators than cover crop. After 17 years, crop yields were 23–28% greater for the 2‐yr and 3‐yr rotations than monoculture WW in the presence of red clover. In the absence of red clover, yields were 32–39% greater for the 2‐yr and 3‐yr rotations than monoculture WW. However, the soil health indicators were significantly greater for monoculture WW than the 2‐yr and 3‐yr rotations. These results suggest WW enhanced soil health while crop rotations with soybean negatively impacted most biochemical soil health parameters.
... The shift to conservation practices such as no-tillage and zone tillage mainly reflects efforts to reduce production and maintenance costs (Allmaras & Dowdy, 1985;Raper & Bergtold, 2007) as well as the recognition that intensive tillage can contribute to a decrease in overall soil health by accelerating the breakdown of soil organic matter and increasing the rates of soil erosion (Edwards, Shipitalo & Norton, 1988;Olson, Lang & Ebelhar, 2005;Koch & Stockfish, 2006;Zhang, Su & Nie, 2009). Zone tillage has been proposed as a promising alternative tillage system that may combine the potential to increase soil health from conservation tillage with the yield benefits of conventional tillage in cool humid climatic zones (Drury et al., 2003;Shi et al., 2011). ...
... Similarly, in Minnesota, corn grain yield increased by 4% with chisel plow tillage at 20 cm depth in a 3 yr study (Vetsch & Randall, 2004) and by 5% with zone tillage at 38 cm depth in a 4 yr study (Vetsch et al., 2007) compared to no-till in both cases. Much larger increases were shown by Drury et al. (2003) who reported in an Ontario study that zone tillage at 15 cm depth increased corn grain yield by 24% over the no-till system. Yet, not all studies show a yield benefit with zone tillage over no-till. ...
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Adoption of conservation tillage practices has increased over the past 30 years in the United States. Research is needed to evaluate if reduced tillage practices are compatible with manure injection on dairy farms. Two corn (Zea mays L.) silage studies were conducted in New York to evaluate the impact of zone tillage depth and tillage intensity on early plant growth and soil nitrate‐N, and corn silage productivity, quality and nutrient uptake at harvest. Treatments included three zone tillage depths (0‐, 18‐ and 36‐cm; with aerator seedbed preparation) for study 1 (2012‐2013) and three tillage intensities [(no‐tillage; reduced tillage (aerator seedbed preparation without zone tillage) and intensified reduced tillage (aerator seedbed preparation plus zone tillage at 18‐cm depth)] for study 2 (2014‐2016). Manure was injected in the spring and all fields had a manure and zone tillage history. Zone tillage depth did not impact early plant growth, soil nitrate‐N content at V5‐V6, corn silage yield, quality, corn stalk nitrate test (CSNT)‐N or nutrient removal with harvest. The CSNT‐N levels exceeded 2000 mg NO3‐N kg–1 confirming sufficient N for each treatment. Study 2 showed no impact of tillage intensity on corn growth, yield or nutritive value either and CSNT‐N levels always exceeded 2000 mg NO3‐N kg–1. These findings show that on fields with a history of manure addition and reduced tillage, manure injection followed by planting, without further seedbed preparation or zone tillage can maintain yields, quality and conserve N while reducing soil disturbance and tillage‐associated fuel, equipment, and labor costs. This article is protected by copyright. All rights reserved
... The effects of different tillage systems on soil characteristics and crop yield depend on climatic conditions, and soil and crop types [5]. In temperate climatic regions, maize yields under no-tillage (NT) were found to be either similar or lower compared to CT with a cool-humid climate or on poorly drained soils [8][9][10], but NT has been found to reduce wind-water erosion [11,12], increase the water infiltration rate and soil water content [11,13,14], and reduce labor and fuel inputs, making NT a more attractive commercial cropping practice compared with most conventional tillage systems [15,16]. Tillage research in the loess plateau areas reported that conventional tillage accelerated soil degradation, increased water shortage, and decreased crop water use efficiency [17][18][19]. ...
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Cropping system models can be useful tools for assessing tillage systems, which are both economically and environmentally viable. The objectives of this study were to evaluate the decision support system for agrotechnology transfer (DSSAT) CERES-Maize model’s ability to predict maize growth and yield, as well as soil water dynamics, and to apply the evaluated model to predict evapotranspiration processes under conventional tillage (CT) and no-tillage (NT) systems in a semi-arid loess plateau area of China from 2014 to 2016. The field experiment results showed that NT increased the surface soil bulk density and water-holding capacity but decreased the total porosity for the surface soil and the maize grain yield. Model calibration for maize cultivar was achieved using grain yield measurements from 2014 to 2016 for CT, and model evaluation was achieved using soil and crop measurements from both CT and NT for the same 3 yr period. Good agreement was reached for CT grain yields for model calibration (nRMSE = 4.02%; d = 0.87), indicating that the model was successfully calibrated. Overall, the results of model evaluation were acceptable, with good agreement for NT grain yields (nRMSE = 4.26%; d = 0.86); the agreement for LAI ranged from good to moderate (RMSE = 0.30‒0.31; d = 0.84‒0.85); the agreement for soil water content was good for NT (RMSE = 0.03‒0.08; d = 0.81‒0.95), but ranged from good to poor for CT (RMSE = 0.06‒0.09; d = 0.42‒0.88); the overall agreement between measured and simulated soil water varied from poor to good depending on soil depth and tillage. It was concluded that the DSSAT CERES-Maize model provided generally good-to-moderate simulations of continuous maize production (yield and LAI) for a short-term tillage experiment in the loess plateau, China, but generally good-to-poor simulations of soil water content.
... Ontario, to improve the sustainability of the agroecosystem, cultivation of red clover (T. pratense) under wheat (Triticum spp.) is a recommended practice in corn-soybean-wheat rotation (Wyngaarden et al., 2015), and the benefits of similar practices in terms of soil fertility and crop yield have been documented by some other studies (Dapaah and Vyn, 1998;Drury et al., 2003;Miguez and Bollero, 2005;Henry et al., 2010;Gaudin et al., 2014). ...
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Several governmental programs have been established throughout Canada to foster agriculture sustainability. As a best management practice, cover crops (CCs) limit soil erosion and prevent nutrient losses in agroecosystems. Yet, the variable effects of CCs on cash crop productivity previously reported may limit their large-scale adoption by farmers. To address this variability, we conducted an unweighted meta-analysis including 2274 observations from 86 field studies conducted under humid temperate climate to evaluate yield response to CCs for three annual cash crops. Overall, CCs increased corn and small grain cereal yields by 13% and 22% respectively, but did not affect soybean yield. Legume CCs alone or mixed with grasses provided the highest small grain cereal and corn yield increases compared to non-legume broadleaf and grass CCs. CC benefits increased with N content in CC aboveground biomass but decreased when N fertilizer inputs applied to corn exceeds 60 kgN.ha-1. Greater precipitation and N fertilizer inputs reduced the negative effect of grass CCs on corn yield, while benefits of legume CCs were highly resilient to precipitation variations. CC benefits on corn yield increased through time, and at low soil organic matter content, especially at low N fertilizer inputs. These results evidence the complex interplay between cash crop productivity, CC management and environmental factors – related to N inputs from CCs, changes in soil properties (e.g., increased organic matter, improved soil structure or microbial activity) or potential competition for water under drier conditions – which provide new perspectives to promote CC inclusion in cropping systems.
In this thesis, we present a machine learning (ML) pipeline that produces data-driven global maps to address the global agricultural issues, such as assessing the spatial distribution of the productivity conservation agriculture (CA) versus conventional tillage (CT) under current and future climate. Our approach covers the selection and comparison of ML algorithms, model training, tuning with cross-validation, testing, and results global projection. We demonstrate its relevance using a global dataset we conducted which comparing the crop yields of conservation agriculture (CA) and no tillage (NT) vs. conventional tillage (CT) systems with a wide range of crop species, farming practices, soil characteristics and climate conditions over crop growing season. Through this ML pipeline, various models for classification, regression and quantile regression are trained based on 12 mainstream ML algorithms. The models are used to map the crop productivity of CA and its variants vs. CT at the global scale under different farming practices and climate conditions in the past (1981-2010), current (2011-2020) and future (2051-2060) scenarios. We reveal large differences in the probability of yield gains with CA across crop types, agricultural management practices, climate zones, and geographical regions. We show that CA stands a more than 50% chance to outperform CT in dryer regions of the world, especially with proper agricultural management practices. In conclusion, CA appears as a sustainable agricultural practice if targeted at specific climatic regions and crop species.
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No tillage (NT) is often presented as a means to grow crops with positive environmental externalities, such as enhanced carbon sequestration, improved soil quality, reduced soil erosion, and increased biodiversity. However, whether NT systems are as productive as those relying on conventional tillage (CT) is a controversial issue, fraught by a high variability over time and space. Here, we expand existing datasets to include the results of the most recent field experiments, and we produce a global dataset comparing the crop yields obtained under CT and NT systems. In addition to crop yield, our dataset also reports information on crop growing season, management practices, soil characteristics and key climate parameters throughout the experimental year. The final dataset contains 4403 paired yield observations between 1980 and 2017 for eight major staple crops in 50 countries. This dataset can help to gain insight into the main drivers explaining the variability of the productivity of NT and the consequence of its adoption on crop yields.
We conducted field experiments during the period 2007-2010 to explore methods of controlling growth of hairy vetch (HV) living mulch in stands of forage corn produced without herbicides in cold region of Japan. Corn seed was planted without tilling into HV sod established in the previous year. The HV sods were then mown before corn seed germination. Mown dead sods and regrown new shoots of HV effectively depressed weeds without herbicides. However, delaying the date of HV sowing or advancing the date of corn sowing allowed excessive regrowth of HV, with consequently reduced corn yields. Optimum sowing times for weed suppression and higher corn yield were mid-September for HV and mid-May for corn. Corn yields from this combination of sowing times matched those from conventional tillage with herbicide application. We demonstrated further that vertical disc harrow cutting of HV sod before corn planting suppressed regrowth of HV more effectively than mowing, if the harrow gang angle adjusted to prevent overturning of sod. This disc harrow procedure reduced losses in corn yield caused by delaying the date of HV sowing.
The yield of silage corn in a no-tillage system was compared with that in a conventional tillage system over a five-year period. In a no-tillage system, the emergence of corn was satisfactory, although there was a tendency toward a lower percentage of emergence. In addition, the soil water content during growth was significantly higher and the height of corn seedlings during the early growth stage was higher. There were no differences in the contents of 8 chemical constituents of corn (ether extract, nitrogen free extract, crude fiber, crude ash, potassium, magnesium, calcium, phosphorus), except for crude protein at the time of harvest between the no-tillage and conventional tillage. In the fifth year of continuous cultivation, the no-tillage system exhibited a tendency of lower crude protein content as compared to the conventional tillage system. In addition, the no-tillage system exhibited a tendency of lower exchangeable calcium content and magnesium content in soil sampled after harvesting. Even after five years of continuous cultivation, the dry matter yield of corn in the no-tillage system did not differ from that in the conventional tillage system. These results indicate that it is feasible to use the no-tillage system for the cultivation of corn in the northern Tohoku region.
A 21 yr field study comparing zone tillage (ZT), no-tillage (NT), and moldboard plow tillage (MP) was used to elucidate tillage effects on soil hydrophobicity (SH) and soil water repellency index (RI) in a cool, humid clay loam soil in southwestern Ontario. The SH was 38% (P ≤ 0.05) greater for ZT and NT than MP, and it was similar between crop row (0.34) and crop inter-row (0.37) for ZT. The RI values were not different among tillage systems, or between the crop row versus crop inter-row positions under the three tillage systems.
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Maintaining long-term soil productivity requires development of cropping systems that provide maintenance or improvement in soil structure and an understanding of associated rhizosphere microbial populations. The objectives of this study were to determine the effects of several crops on soil biomass C and biomass N contents, their within-season variability, and the relationships between changes in soil biomass C, biomass N, and soil structure on a Brookston clay loam soil (fine-loamy, mixed, mesic Typic Argiaquoll). Soil microbial biomass C, biomass N, and soil-structure parameters (wet aggregate stability [WAS], organic carbon [OC], dry aggregate mean weight diameter [MWD], bulk density, and total and air-filled porosity) were measured during the third year of corn (Zea mays L.), soybean (Glycine max [L.], Merr.) alfalfa (Medicago sativa L.), red clover (Trifolium pratense L.), reed canarygrass (Phalaris arundinacea L.), orchardgrass (Dactylis glomerata L.), and no-crop (bare, covered, and shaded) plots at monthly intervals (June, July, August, and September). Reed canarygrass resulted in greater biomass-C contents than both the corn and soybean at all four sampling dates. Soil biomass C under alfalfa was significantly greater than under corn and soybean for both the first and last sampling dates. Forage species did not affect the soil biomass-N content. This study demonstrated the influence of forage species and seasonal variability on concurrent changes in microbial biomass and soil structural properties.
An aggregate is a group of primary particles that cohere to each other more strongly than to other surrounding soil particles. Most adjacent particles adhere to some degree. Therefore, disintegration of the soil mass into aggregates requires imposition of a disrupting force. Stability of aggregates is a function of whether the cohesive forces between particles withstand the applied disruptive force.
In northern regions, no-tillage corn (Zea mays L.) planting often results in reduced and/or delayed seedling emergence and growth. The objective of this research was to evaluate the effects of seed quality on the performance of three commercially available corn hybrids grown with conventional-tillage (CT), no-tillage (NT), and no-tillage with in-row residue removed (NT-R). Field studies were conducted under the three tillage systems with seed lots having high (95–99%), medium (89–98%), and low (84–95%) warm and cold germination test values. Hybrids used were FR20A × FR31, LH74 × LH51, and A632 × LH39. The studies were conducted from 1986 to 1988 on Piano silt loam (fine, mixed, mesic Typic Arguidoll) soils near Arlington and Janesville, WI. There were also early (mid- to late April) and late (mid- to late May) planting dates at Arlington. Increased residue cover with NT and NT-R systems resulted in 2 to 4 °F cooler soil temperatures at planting compared to CT, which reduced average percentage corn emergence by 3%, delayed emergence by 2 to 5 d, reduced vegetative dry weight at 45 d after planting by 30 to 60%, delayed silking 5 to 7 d, and increased harvest grain moisture 1 to 5%. Average grain yields were also reduced by 9% under NT compared to CT. Compared to high quality seed, medium and/or low seed quality caused 4 to 6% lower emergence, delayed emergence less than 1 d, reduced vegetative dry weight by 10 to 15%, extended days to silking by 1 to 2 d, increased grain moisture about 1%, and decreased average grain yield by 4% (despite thinning to constant final stands). Seed quality effects were usually smaller than tillage system effects, and tillage system by seed quality interactions were infrequent. Special concern about seed quality under NT is unwarranted, but to optimize probability for high yields growers should plant high quality seed regardless of the tillage system used. Please view the pdf by using the Full Text (PDF) link under 'View' to the left. Copyright © 1991. . Copyright © 1991 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, 5585 Guilford Rd., Madison, WI 53711 USA
Soil management systems can affect soil physical properties and, thus, have a direct bearing on crop performance. This study determined the effects of continuous long-term conventional and no-tillage management on selected soil physical properties and compared observed yield differences between these tillage systems with soil physical properties. Three Maryland locations, each having randomized complete-block designs with three replications of continuous corn under conventional and no-tillage management, were used. Although soil physical properties within the Ap horizon are not adequate to account for differences in corn yield response, tillage differences in soil physical properties were found for the soils at Sites 1 and 2, which had previously shown tillage yield differences. -from Author
In northern areas where corn (Zea mays L.) is grown, no-till plants develop more slowly and, consequently, could be more susceptible to soil water limitations than plants under conventional tillage. This study was conducted to determine if removing in-row residues by pushing them into the interrow can solve problems related to no-till corn development in droughty soils. Residues were removed to produce a 30-cm band of bare soil along the corn row. This bare row no-tillage (BRNT) treatment was compared with conventional tillage (C), regular no-tillage (NT), and bare no-tillage (BNT) for plant development, plant height, crop yield, soil water content in the upper soil layers, and seed zone temperature. The BRNT seed zone temperature was higher than that of NT and similar to that of C and BNT from emergence to the V6 stage. Accordingly, BRNT plants reached the V6 stage 1.3 and 3.7 d later than C while NT reached the V6 stage 5.0 and 7.2 d later than C in 1990 and 1991, respectively. In 1991, NT plants were further retarded by hot and dry conditions despite the fact that interrow soil water was higher in treatments with interrow residue cover. Height differences among treatments were related to developmental differences. Despite considerable changes in soil temperature, water, developmental rate, and height of plants among treatments during the vegetative stage, reproductive yield was not affected by tillage and residue treatments. Contribution from Agric. Canada, Harrow Res. Stn. and Centre for Land and Biological Resources Res. (no. 92-64). Please view the pdf by using the Full Text (PDF) link under 'View' to the left. Copyright © . .
Residue-related low soil temperatures have been shown to delay corn (Zea mays L.) emergence and silking dates, but it is unclear how residues affect general crop growth during this period. This study was conducted to determine how crop-residue effect on corn development during the vegetative stage affects the measurements of various growth characteristics. The effects of small grain residue cover applied around 50% emergence on corn development (time to reach specific stages), growth (aboveground phytomass, height, N uptake) and soil temperatures were investigated on a Conover loam (mixed, mesic, Udollic Ochraqualf) under irrigated no-tillage conditions. In 1987 and 1988, straw mulch significantly delayed development when compared to a bare soil control, but no consistent difference was found in aboveground phytomass when comparisons were done at similar vegetative stages. Comparisons on a calendar day basis showed significantly lower values for the residue treatment. The latter analysis confounded developmental-delay effects with actual growth. Similar observations were made for height and N uptake. Consequently, an understanding of plant performance in tillage studies, involving significant developmental differences between treatments, requires that the response curve of a growth characteristic over time be coupled with data on development. Contribution from Michigan Agric. Exp. Stn. Research supported in part by Agriculture Canada, Harrow, Ontario. Please view the pdf by using the Full Text (PDF) link under 'View' to the left. Copyright © . .
Low soil temperatures that are induced by crop residue have been shown to delay corn ( Zea mays L.) development. The exact conditions under which retardation takes place and whether the delay is only due to thermal effects still need to be elucidated. This study was conducted to characterize corn vegetative development, with and without residue cover, and to determine if differences in seed‐zone temperature account for the differences in development. The effects of an oat ( Avena sativa L.) straw mulch and an inert poplar excelsior ( Populus ) mulch, applied at second leaf tip emergence and at the time of full extension of the fourth leaf, on seed‐zone temperature, time, and thermal time (daily temperature accumulation) between specific vegetative stages, were investigated on a Conover loam (mixed, mesic, Udollic Ochraqualf) under irrigated conditions. Developmental delays occurred as average soil maxima temperatures, under the mulches, were 2.2 °C lower than the bare soil control. When mulches were applied at second leaf tip emergence, soil temperature‐based thermal time was significantly higher for the oat mulch than for the popular mulch or the bare soil, until the full extension of the fourth leaf in 1988 and the third leaf in 1989. Modeling equations derived from CERES‐MAIZE accurately predicted thermal times to the full extension of the third leaf and sixth leaf for most treatments, but underestimated thermal time for the 1988 oat mulch. When applied at full extension of the fourth leaf, oat straw had minimal effects on development. The differences in thermal time due to the two mulches during the early vegetative stages of corn, suggest that in addition to soil temperature, allelopathy from oat straw may be a source of developmental delay and that its occurrence is weather‐dependent.