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An In-Depth Look at the Influence of Soil Temperature and Moisture in Southern Illinois - Part 3

Published on Wednesday, February 01, 2017

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Influence of Soil Moisture and Temperature on Yield
In the drip-irrigation and sub-irrigation portions of the SIL water management study, XL® 5828™*brand and BECK 6076V2Pbrand were used. The XL® 5828™*brand is an Aquamax® hybrid, therefore, it has an increased ability to deal with moisture stress. In the drip-irrigation portion, we saw less of a response from this product but still had a substantial increase in yield compared to the non-irrigated control (Figure 1). The plant stand in the drip-irrigation portion was comparable to that of the drip-irrigation with tile, but we believe this is because soil conditions were adequate where tile was in place, thus creating a better seed bed that allowed excess water to move down the profile. The tile in the drip-irrigation system improved yield by an average of 22.3 Bu./A. across the two hybrids. Over the season, the soil moisture at the 8 in. depth of the drip-irrigated portion with tile had a 0.7% VWC increase with the control, an 11.3% increase with 30 ft. tile and a 0.1% VWC increase when drip-irrigated (Table 1). The advantage becomes more apparent at the 16 in. depth. Drip-irrigation with 30 ft. tile had the highest average yield compared to any other treatment in the irrigation section of this water management project. The increased infiltration from the tile allowed the water to move downward into the profile, providing adequate soil moisture across the entire soil profile. The 30 ft. tile alone was driest at 8 in. and 16 in., but still resulted in greater yield compared to the control and drip-irrigated without tile. This shows the importance of drainage in southern IL and how draining soils early in the season increases the chance of a successful crop. 

Figure 1. Drip-irrigated 2016 corn yields.

Table 1. Irrigation soil temperatures and moisture means from June 21 to September 14.

Sub-irrigation showed a substantial yield response over the control for both corn and soybeans. Once again, XL® 5828™*brand and BECK 6076V2P brand were used in the corn portion of the study. In the soybean section, XL® 345R4™*brand and BECK 365R2 brand were used. The control had significant stand reduction compared to portions of the study with tile. In corn we saw yield increases of 46.6 Bu./A. with the controlled water table, 45.4 Bu./A. with the sensor-based sub-irrigation portion, and 41.6 Bu./A. with the contour tile drainage over the control when averaged across the two hybrids (Figure 2). The manual sub-irrigation portion only experienced a 36.7 Bu./A. over the control, which is demonstrated in Figure 2 below. The manual sub-irrigation portion had the highest soil moisture at the 8 in. depth which resulted in less water in the subsoil (Table 2). Because the surface looked wet, we did not turn on the water, which could have limited subsurface moisture. There also may have been too much water on top and without a sensor, we may have over watered this portion of the study. The contour drainage section had the highest subsoil moisture of any non-irrigated treatment. The sensor data shows that if tile is in place, we can decrease upper soil moisture but increase soil moisture deeper in the profile where the corn roots are. With better subsurface soil moisture and better drainage in the spring, the contour treatment was within 6.5 Bu./A. of the controlled water table and sensor based for both XL® 5828™*brand and BECK 6076V2P brand (Figure 2). The controlled water table took longer to recharge, but resulted in more variability in soil moisture throughout the entire season.  

Figure 2. Sub-irrigated 2016 corn yields.

Table 2. Irrigation soil temperatures and moisture means from June 21 to September 14.

In soybeans, sensor-based-irrigation resulted in the greatest yield increase compared to the control (Figure 3). The CropX data ensured the proper amount of water was used, which helped increase the yield compared to the manual sub-irrigation. Tile drainage alone did not see an improvement in soybeans like the corn crops did. Soybeans can compensate for a lack of stand; therefore, early drainage may not influence yield in soybeans as significantly as it does in corn. While we have seen an increase in yield by holding the water back with the gate in the controlled table, this may not provide enough moisture to the soybean plant as they have a shallower root system than corn. 

Figure 3. Sub-irrigated 2016 soybean yields.

In the tile spacing study, XL 6365AM™*brand and BECK 394L4 brand were used. For the corn portion of the study, the 24 in. tile depth vs. 36 in. depth increased the yields of 15 ft. and 30 ft. tile spacing by 3.0 Bu./A. and 4.0 Bu./A., respectively (Figure 4). However, the 24 in. depth reduced yield on the 60 ft. spacing by 13.1 Bu./A. compared to the 36 in. depth. For soybeans, there was less variation in yield at the 36 in. depth vs. the 24 in. depth (Figure 5). Between tile spacing there was less than 0.4 Bu./A. difference at the 36 in. depth. However, at the 24 in. depth there was a 3.9 Bu./A. difference between tile spacing. Both the 24 in. and 36 in. deep tile increased yields for all tile spacings.

Figure 4. Tile spacing 2016 corn yields.

Figure 5. Tile Spacing 2016 soybean yields.

The soil moisture at the 8 in. depth was reduced over the tile, but was greater over the tile at the 16 in. depth (Table 3). The 15 ft. tile spacing had the least amount of soil moisture over and between the tile. However, the 15 ft. had the greatest yield at the 24 in. depth for both corn and soybeans. For corn, the 15 ft. spacing had the greatest response at both the 24 in. and 36 in. depth. This shows the importance of having prime conditions and the proper seed bed, as we saw better stands thanks to the increased drainage with 15 ft. tile when compared to the control. Because corn struggles to compensate for a reduction in stand compared to soybeans, having a prime seed bed is critical and helped increase yields by 58.2 Bu./A. compared to no-tile in corn in this study.

Table 3. Tile spacing soil temperatures and moisture means from June 21 to September 14.

While 2016 was the first year of our water management at the SIL PFR site, we saw promising results with the use of tile. We raised some of the best crops on the entire farm on the tiled ground. As we move forward, it will be interesting to see the long-term data with tile in southern IL. We will be able to relate long-term sensor data to yield data and help explain “the why.” 


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Author: Joe Bolte

Categories: PFR, PFR Reports


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