Management of Fine Textured Poorly Drained
Soils for Intensive Agriculture
Researcher: Dr. J.A. Stone, Harrow Research Station, Principal
Researcher. Aspects of this proposal have been coordinated with a similar
proposal being submitted by researchers from the Dept. of Land Resource
Science, University of Guelph, to facilitate extrapolation of results
to the various soils and climatic conditions across the province.
- To contribute to the development of a row crop management package
which will improve and maintain soil structure through -
- the selection and evaluation of several legume - grass forage
mixes relative to which will provide the most improvement in
soil structure in the shortest time (1988-90)
- the determination of the minimum amount of tillage required
to obtain yields equivalent to conventional tillage (fall mouldboard
plow) in a corn-soybean rotation and determination of the effect
of reduced tillage on soil structure (1988-91)
- the evaluation of corn polyculture (intercropping corn with
legume and grass forages) under conventional and conservation
tillage systems relative to improvements in soil structure,
reduction in nitrogen requirements, and effects on yield (1989-91).
- To minimize losses in soil productivity and environmental hazards
resulting from erosion, runoff, and compaction.
- To improve the market position of Ontario farmers by providing
more efficient use of fertilizer and by lowering fuel costs associated
Experiment 2 - The determination of the minimum amount of tillage
required to obtain yields equivalent to conventional tillage (fall moldboard
plow) in a corn-soybean rotation and determination of the effect of
reduced tillage on soil structure.
Agronomic Analysis Weather Effects - Weather conditions in 1988-90,
had a very significant overriding influence on soil and plant measurements.
In general Corn Heat Units were similar for 1988-90 while rainfall during
the same period was variable within growing seasons as well as between
years as observed in the low to high rainfall pattern in 1988; the very
high to low pattern in 1989; and average early to low mid season and
then high rainfall pattern in 1990. 1988 had below normal rainfall with
higher than average Corn Heat Units early in the season, resulting in
very poor corn plant growth in May, June and July and better than average
growth for soybeans. Corn Heat Units were higher than average for 1988
than for 1989-90. Early plant development influenced yields with corn
grain yields equivalent to soybeans in 1988. Very wet conditions (flooding
in June and July) early and mid season in 1989, delayed corn emergence,
days to silking and wet conditions during pollination reduced grain
yields although corn height was better than average. Early and mid-season
soybean growth was reduced and planting was delayed, restricting soybean
yields for 1989. Rainfall during 1990 was above average in May, delaying
corn planting and below average for June and July. Early rainfall delayed
corn growth while above average Corn Heat Units and rainfall in August
and September resulted in average corn and soybean yields.
Rotations - Rainfall accounted for considerable variation in tillage
treatments and rotation effects on yields. Each rotation was started
in 1987 with corn on Site 1 and soybeans on Site 2. Soybeans improved
in yield in 1988 and 1990 after rotation with corn. Similar trends indicate
that corn grain yields improved following soybeans in 1987 and 1989
for Site 2. Adverse and variable weather conditions account for the
highly significant differences in yields among years and the effects
on rotations at both sites and for the large yield differences from
year to year. Residue cover varied considerably as a result of the amount
of plant material produced the previous year and the type of rotation
Percent residue from the previous corn rotation (87 and 89), produced
higher residue cover at Site 1 in 88 and 90, than residue from previous
soybeans. At Site 2, 1989 residue from poor corn growth in 88 was similar
to the residue produced by the 87 soybean rotation crop.
Tillage Treatments - If corn or soybeans are analyzed by combining
sites for each crop, then a significant interaction for soybeans can
be observed, indicating that tillage treatments were dependent on year
conditions and did not perform consistently from year to year. If analyzed
by locations then Site 2 also appears to have tillage interactions which
is very close to being statistically significant and dependent on year
conditions. This is further supported by plant growth parameters and
plant residues, which varied from year and were not consistently significant
because of extremes in weather conditions.
Variable weather conditions in 1988, 89 and 90 had a strong influence
on soil and plant growth parameters results. Weather conditions had
a greater influence on yields and plant growth parameters than rotations.
The effects of weather conditions and tillage treatments on soybean
yields were inconsistent because of interactions. The best row crop
tillage treatment yield results were for fall chisel plowing followed
by fall chisel plowing for the corn crop and only spring secondary tillage
for the following soybean crop. Ridge tillage similar yields but was
the most inconsistent over the years and locations. Percent plant residue
was highest for ridge, spring secondary and fall chisel plowed tillage
treatments. Soil moistures were higher after corn rotations and chisel
plowed tillage treatments of corn and soybeans. Soil aggregate size
improved with chisel plowing and minimum spring secondary tillage while
ridge tillage maintained water stable aggregate structure better than
chisel or moldboard plowing. Rotations did not improve wet aggregate
stability over the three years. Bulk density and soil porosity results
were inconsistent for tillage treatments and rotations.
Experiment 3 - The evaluation of corn polyculture (intercropping
corn with legume and grass forages) under conventional and conservation
tillage systems relative to improvements in soil structure, reduction
in nitrogen requirements and effects on yield.
Weather conditions had a strong influence on this experiment which
was complicated by degraded soil structure and as a result very poor
drainage. Corn heat units were average for 1989, slightly below for
1990 and considerably above average for 1991 compared to ten year averages
for each month. In 1989, plots were planted and damaged by flooding
on two different occasions early in the season.
Plant development was influenced by flooding when compared to other
years. 1990 was an average year with no extreme weather conditions but
wet conditions in May delayed planting to May 31 for corn and June 1
and 15 for intercrops. Hail damage in late August caused some leaf damage
but growth was not reduced. In 1991, a wet May delayed planting as in
1990. This was followed by very hot and dry weather causing very poor
intercrop germination, plant stunting, inconsistent tassel and silk
development and poor yields.
Results from yield analysis indicated that there were no significant
differences for yields among the treatments for any year. Spring and
fall tillage did not result in a yield trends, except that fall tillage
produced slightly higher yields in 1990 and 91. Planting intercrops
at the 3-4 leaf stage resulted in higher yields than planting intercrops
at corn planting. Corn yields were enhanced by reed canary grass for
spring tillage in 1989 and 90 as compared to no intercrops (Bare). Reed
canary grass also supported corn yields in fall tillage in 1990. Hairy
vetch supported yields similar to bare treatments in the driest year
and 1990. Red clover enhanced yields in the 1989 only when moisture
was abundantly available. Hairy vetch and reed canary grass enhanced
yields and plant development in normal and stress years as compared
to other intercrops.
The project was extended for another year (1992) because of interest
in establishing some significant differences for plant growth parameters
between corn and intercrops and to study nitrogen relationships between
crop production and intercrops. Agronomic measurements and nitrogen
samples were assessed. In 1992, wet conditions resulted in very poor
intercrop emergence due to flooding conditions which are common for
degraded soil conditions.
Soil measurements were taken in 1989 and 1990 and only partial data
is on file. Soil parameters were not completed because of the resignation
of the soil scientist in late 1990. The position and technical support
were frozen at the time.
Yield results obtained over years of extreme weather conditions on
plots that were in continuous corn for 26 years indicated that planting
intercrops such as hairy vetch or reed canary grass would support yields
equal to conventional row crop production.
Tuesday, May 10, 2011 11:19:47 AM