Effect of Tillage Method and Soil Moisture Conditions on Crop Yields:

A Preliminary Assessment

Cavers, C. G., Fitzmaurice, J. L. and Grieger, L.

Soil Strength (Compaction) Initial Interpretations:

Acknowledgements

Effect of Soil Moisture Regime on Crop Yield Crop Yields by Tillage Method and Moisture Regime

References

Background

Methodology

Soil compaction is a condition impacting one of the soil health

components that is compounded under conditions of excess soil

moisture1. In an effort to quantify the negative effects of soil compaction,

and conversely the potential benefits of strategic tillage practices, an

experiment was constructed to determine which tillage practices, and

under what conditions, impede or improve water movement and soil

compaction to ultimately influence crop yield.

As a preliminary study leading up to a 2018 study examining the effect of

canola stand establishment, tillage and soil moisture on canola

performance, activities in 2017 were conducted to begin to answer the

following questions:

• Does soil moisture influence the crop response to the impacts of

tillage?

• Does tillage influence crop performance positively or negatively and

under which conditions?

• Does crop variety respond differently to the above treatments? (this

will be changed to canola seeding densities in 2018.) 1 1

1

1

1 1

1

1

Tillage treatments were established on June 9, 2016 (under wet soil

conditions) and seeded to flax at AAFC-Portage. In 2017, fertilizer was

broadcast applied according to soil test recommendations (N-P-K-S) prior

to planting canola. The trial was planted on June 6, harvested Sept 28

and 29. Soil strength measurements using a cone penetrometer were

taken on Oct 4, 5, 13 and 15.

Table 1. 2016 weather data for AAFC-Portage.

Table 2. 2017 weather data for AAFC-Portage.

General 2017 soil moisture measurements taken on-site at a depth of 10 cm

ranged from a maximum of approx. 36% volumetric at the start of the growing

season to a minimum of approx. 20% just prior to rainfall in mid-September,

which is approximately 5.75 inches of available water in the top 36 inches (90

cm) of the soil profile, but does not account for the contributions of shallow

water table and capillary action. Water use calculations derived by

Saskatchewan Agriculture and Food2 estimate a 40-bushel/acre canola crop

growing in the Black soil zone to use 12.6 inches in the growing season (or

as 7.0 kg/ha/mm, as the WUE reporting units used by Hatfield et al3).

Based on these estimates, preliminary assessment suggests nearly 50%

of the water needed by a 40-bushel canola crop would come from stored soil

moisture, with the remaining 50% provided by growing season precipitation.

1. Soil moisture is the dominant factor affecting crop yield and soil strength,

with interactions taking place as conditions change from wet to dry.

Irrigation increases total average yield of flax and canola crops, even when

conditions of excess moisture were prevalent in 2016.

2. Impact of tillage changes with changing soil moisture conditions from 90%

of normal (2017 dryland) to 170% of normal (2016 irrigated). As the effect

of the tillage method dissipates from Year 1 to Year 2, trends and

interactions may change over time. Why and how this happens, and

whether this phenomenon can be predicted in advance, is yet to be

understood.

3. Soil compaction values remained below critical values of 290 psi (2 MPa),

but differences may still exist among tillage treatments and moisture

regimes that could influence crop yields.

4. Impact of crop variety is more consistent over varying conditions. In the

case of both flax and canola, one of the four varieties tested was

significantly lower-yielding than the others, regardless of tillage or moisture

regime (not shown).

• Canola Agronomy Research Program

• Canola Council of Canada agronomists (A. Brackenreed and J. Cornelsen)

• AAFC Technical Services Unit (M. Chubey, J. Freeman and G. Gaskin)

• K. Egilson, PAMI

• AAFC-Portage staff (D. Bouchard, Z. Xing)

• Byron Irvine

1Manitoba Agriculture, 2006. Soil Compaction, in Soil Management Guide. 2https://www.canolacouncil.org/media/516663/tips.pdf 3Hatfield, J. L, Sauer, T. J. and Pruger, J. H. 2001. Managing Soils to Achieve

Greater Water Use Efficiency: A Review. USDA-ARS/UNL Faculty.

Observations

Month CHU % normal Rainfall (inches)

% normal Irrigation (inches)

# applications

June 486 106 3.9 157 0

July 745 101 3.2 114 1.0 2

Aug 705 104 4.2 137 1.5 3

Sept 466 122 2.0 103 2.0 4

Oct 126 142 2.6 142

Total 2618 111 15.9 133 4.5 9

Crop yields in 2016 and 2017 were significantly higher under irrigated conditions

versus dryland, even though total precipitation amounts were greater than

normal growing season precipitation values. Additional water applied by

irrigation does not appear to have caused an excess moisture condition, and

may have masked some negative effects of soil compaction.

Figure 1a. 2016 flax yields. Figure 1b. Flax plot on raised beds (RB)

vs. vertical tillage (VT).

Figure 2a. 2017 canola yields. Figure 2b. Aerial view of canola plots.

Figure 1 a) Vertical Tillage (VT) equipment; b) seedbed and c) soil strength data.

Figure 2 a) Conventional Tillage (CT) equip; b) seedbed and c) soil strength data.

Figure 3 a) Deep Tillage (DT) equip; b) seedbed and c) soil strength data.

Figure 4 a) Raised Bed (RB) equip; b) seedbed and c) soil strength data.

Fig.1a

Fig. 2a

Fig 3a

Fig 4a

1b

2b

3b

4b

1c

2c

3c

4c

Figure 5a. 2016 flax yields

under irrigation.

Figure 5b. 2016 flax yields

under dryland.

Figure 6a. 2017 canola yields

under irrigation. Figure 6b. 2017 canola yields

under dryland.

Month CHU % normal Rainfall (inches)

% normal Irrigation (inches)

# applications

June 457 89 3.1 119 0 0

July 754 102 1.9 68 2.0 4

Aug 665 98 0.5 16 3.0 5

Sept 334 92 3.9 217 0.5 1

Total 2210 96 9.4 90 5.5 10