Effect of Optimal Water Management for Sustainable and Profitable Crop Production and Improvement of Water Quality in Red River Valley
Despite unusual weather, the research and education programs progressed well in 2014. Due to an extended cooler than normal spring, the growing season was delayed until mid to late May. There were frequent rainfall events in June followed by cooler than normal temperatures in July. Unfortunately, the period for optimizing water management using the controlled drainage system could only be done from July 22 to September 4. For research purposes, water could only be added to the subirrigation field for two weeks in late July and August. The crop yields varied from the Clay County average by -20.8%, 48.9%, 38.2%, and 53.6% for the undrained, free drained, control drained, and control drained plus subirrigated fields, respectively. The low yield in the undrained field was due to excessive waterlogging stress in June when the water table was less than 60 cm from the soil surface for 37 days. Water quality monitoring indicated that higher nitrate-N concentrations and electrical conductivity (EC) were found in drainage outflow than that from the surface drainage. A distinct difference in water quality between the subsurface water and surface water was observed from the four fields. Control drainage implies less water and less nitrate-N in the surface water, but an annual water balance for the controlled drainage and subirrigation field showed a 54.2 mm deficiency between inflow and outflow, which implies an adequate water supply for crop use. In addition, the field was used as an outside classroom for an NRCS workshop where the research team were the main presenters.
The objectives of this project were to:
- Optimize water management through a controlled drainage and subirrigation system on a farmer’s production field;
- Compare yield differences between undrained (UD), free drainage (FD), controlled drainage (CD), and controlled drainage plus subirrigation (SI) fields;
- Monitor water quality (e.g. nitrate-N, phosphorus, turbidity, salinity, etc.) and quantity for the different water management practices; and
- Estimate the total annual water balance in the UD, FD, CD, and SI fields.
- Water table
The daily average depth to water table and rainfall totals from each of the four fields are presented in Figure 1. After April 28, the water tables started to rise in each field due to snow-melt water infiltration. Without tile drainage, the water table in the UD (or surface drained only) field rose to 1.1 ft below the soil surface, while the water tables in the other three fields with tile drainage were around the drain depth at 3.5-4 ft deep. From June 15 to July 12, when it rained almost every day, the water table in the UD field was close to the soil surface, while the water tables in the CD and SI fields were maintained at about 2 ft from the surface. In early August, when the water tables dropped to below the drain depth (around 4 ft), subirrigation was applied to meet crop water needs. Two irrigations were applied to the SI field as indicated by the green line in Figure 1. In early September, when frequent rainfalls resumed, the water tables rose only in the UD and SI fields due to their higher soil water contents, while in the FD and CD fields, the rain water replenished the soil profile, but did not bring the water table above the drain. In 2014, water tables were within 2 ft of the surface for 36, 8, 12, and 7 days in the UD, FD, CD, and SI fields, respectively. Considering only the growing season, the depth to water table for the two middle wells averaged 3.0, 4.4, 4.4, and 3.7 ft below soil surface from May 1 to September 30, 2014 for the UD, FD, CD, and SI fields, respectively. The shallow water table in the UD field was due to lack of drainage, while the shallow water table in the SI field was due to controlled drainage holding water in the crop root zone and the two subirrigation events. The practice of drainage water management is to ensure that the depth to water table is optimal for crop water use, but without flooding the field or creating waterlogging conditions. Among all four fields, the SI approach was the best in terms of water table control.
The yield for the four fields was estimated using two methods. The first by taking hand samples (two rows, 30 ft long area at six locations in each field) and the second using the farmers’ weight cart measurements (Table 1). The average soybean and corn yield in Clay County, MN is also shown in Table 1 for comparison.
Due to the high difference between the hand-yield estimate and weight-cart yield estimate, comparison with the county average was made using the yield from the weight carts. In addition, the crop yields across the four fields were difficult to compare due to differences in crop types, varieties, fertilization, tillage, and other management practices. For example, crop yields showed a significant yield loss (27.4 bu/ac, 20.8%) in the UD field likely due to the extended waterlogging conditions. For the other three fields the yields were 48.9, 38.2, and 53.6% higher than the county average in the FD, CD, and SI fields, respectively. The two subirrigation events increased yield by 11.1% compared to the CD soybean (both fields had the same soybean variety, same soil series, and had the same field operations). In retrospect, based on the growing season moisture conditions, subirrigation may not have been needed but was applied for research purposes.
- Water quality
Weekly water samples were taken from the controlled drainage structures and the drainage ditch adjacent to the field both upstream and downstream from the tile discharge. The water samples were sent to a laboratory at NDSU for analysis. In addition, on-site measurement of critical water quality parameters was also performed. When surface runoff and free drainage flow were present, water samples were also collected and analyzed. The results for nitrate-N, P, K, and EC in the CD, SI, and upper and down streams of the field are shown in Figures 2, 3, 4, and 5.
A higher nitrate-N concentration was found in the drainage outlets than that in the surface drainage ditch, similar to what we found in previous years. Phosphorus concentration was similar in drainage effluent and surface ditch water, while the high P concentration in the SI field did not pollute the surface ditch water because it was retained in the field due to drainage control. It was not known where the high P came from, while the only possible reason might be through SI water. A higher potassium concentration was found in the surface water than that in the drainage effluent. The EC was several orders’ higher in the drainage effluent than that in the surface ditch water. Therefore, a distinct difference in water quality between the subsurface water and surface water was observed as it was indicated by the four figures.
Drainage was controlled from July 22 to September 4 in the CD and SI fields and subirrigation was applied from July 28 to August 12. Sudden changes in water quality corresponded to these events in water management. In summary, tile drainage water contained higher nitrate-N, P, and EC than the surface water, but less K. When control drainage worked from July 22 to September 4, it retained water and its chemicals in the field.
Additionally, turbidity, EC and water temperature were measured weekly using in-situ sensors. The results are shown in Figures 6 and 7 for turbidity and temperature in the outlets and ditch water.
Turbidity indicates the presence of sediments or transparency in the water. A standard of 10 NTU is set for chronic turbidity for Minnesota fisheries, so regardless of the difference in turbidity between surface and subsurface waters, they were below the standard. As clear difference in water temperature was observed between surface and subsurface waters. The surface water was always warmer than the subsurface water except on September 11, and after October 9. Average water temperature was 6.2 oF warmer in the surface than that in the subsurface water from May 6 to November 6, 2014. The water temperature difference could have some impacts on aquatic life in the adjacent surface water system. The surface water warmed up quickly as the water temperature in the downstream after the drainage water was introduced was only 1.37 oF colder than that in the upstream.
- Annual water balance for the SI field
Soybean was planted on May 24, germinated on May 29, and harvested on October 7 in the CD and SI fields. Drainage was controlled from July 22 to September 4 and subirrigation was applied from July 28 to August 12. A simplified water balance for the SI field is shown in Figure 8, with the inflow placed at the top and outflow at the bottom of the figure. The rainfall, drainage, and subirrigation were all measured in the field, while the ET was estimated from soybean water use from NDAWN Fargo station (http://ndawn.ndsu.nodak.edu/crop-water-use.html).
Monthly water balance for the soybean growing season in the SI field is included in Table 2.
When considering the water balance in the growing season, there was a 54.2 mm water deficiency. This should not create a problem to the crops because the maximum soil water holding capacity could be more than 200 mm in the root zone for this soil type. With sufficient moisture storage from rainfall in May and June, the moisture deficiency plus some water loss from surface runoff and deep seepage that were not included in the calculation, may not be enough to create drought stress to soybean growth. However, without subirrigation in July and August when crop water demand is maximized, soil water deficiency wouldn’t be 54.2 mm. As seen in Figure 1, the water table in the CD field was near 1.8 m (6 ft), while the water table in the SI field was brought up to 1.1 m (3.5 ft). The capillary rise from the shallow water table can definitely supply water to meet crop water needs, as an 11% crop yield increase was obtained due to the SI effort.
A detailed water balance for all four fields will be included in future publications. However, a simplified water balance excluding surface runoff and in-situ evapotranspiration measurement is included in Figure 9 and Table 3 for the CD drained field.
The FD field was planted with soybean on May 22, germinated on May 27, and harvested on September 26, 2014. The simplified water balance is shown in Figure 10 and monthly water balance in Table 4.
The UD field was planted with corn on May 25, germinated on May 31, and harvested on October 24, 2014. The simplified water balance is shown in Figure 11 and monthly water balance in Table 5.
- Figure 3. Phosphorus concentration at down and upper steams, control drained (CD), and control drained and subirrigated (SI) outlets in 2014.
- Figure 8. Water balance for major inflow (rainfall and subirrigation) and outflow (drainage and evapotranspiration, ET) in the controlled drainage and subirrigation field in 2014.
- Figure 9. Water balance for major inflow (rainfall) and outflow (drainage and evapotranspiration, ET) in the controlled drainage field in 2014.
- Figure 11. Water balance for major inflow (rainfall) and outflow (evapotranspiration, ET) in the surface drainage field in 2014.
- Table 2. Monthly water balance in mm per month at the controlled drainage and subirrigation field in 2014.
- Table 3. Monthly water balance in mm per month at the controlled drainage field in 2014.
- Figure 1. Daily average water table changes in undrained (UD), free drainage (FD), controlled drainage (CD), and controlled drainage and subirrigation (SI) fields in 2014.
- Figure 2. Nitrate-N concentration at down and upper steams, control drained (CD), and control drained and subirrigated (SI) outlets in 2014.
- Figure 5. Electrical conductivity at downstream and upsteams locations, control drained (CD), and control drained and subirrigated (SI) outlets in 2014.
- Figure 6. Water turbidity at the down and upper streams, control drained (CD), and control drained and subirrigated (SI) outlets in 2014.
- Figure 7. Water temperature at the down and upper streams, control drained (CD), and control drained and subirrigated (SI) outlets in 2014.
- Table 1. Crop yield for the undrained (UD), free drained (FD), controlled drained (CD), and controlled drained and subirrigated (SI) fields compared to Clay County averages in 2014.
- Table 5. Monthly water balance in mm per month at the surface drainage field in 2014.
- Figure 4. Potassium concentration at down and upper steams, control drained (CD), and control drained and subirrigated (SI) outlets in 2014.
- Figure 10. Water balance for major inflow (rainfall) and outflow (drainage and evapotranspiration, ET) in the free drainage field in 2014.
- Table 4. Monthly water balance in mm per month at the free drainage field in 2014.
Impacts and Contributions/Outcomes
- Jia, X., D. Steele, T. Scherer, K. Kolars, and K. Horntvedt. 2014. Measuring subirrigation efficiency and uniformity on two subirrigation fields in the Red River Valley. 2014 Eastern South Dakota Water Conference. October 29, 2014. Brookings, SD.
- Jia, X. 2014. Subirrigation design. 2014 Extension Subsurface Drainage Design & Water Management Workshop. Wahpeton, ND. February 11-12, 2014.
- Jia, X. 2014. Tiling water management. North Dakota’s 11th Annual Certified Crop Advisers Meeting. Fargo, ND. January 21, 2014.
- Jia, X. 2014. Tile drainage converted to controlled drainage and subirrigation. Red River Basin Commission 31st Annual Conference. Fargo, ND. January 13, 2014.
- Jia, X., T. F. Scherer, D. Lin, X. Zhang, and I. Rijal. 2014. Comparison of reference evapotranspiration calculations for southeastern North Dakota. Irrigation & Drainage Systems Engineering 2:112. doi:10.4172/2168-9768.1000112.
- Rahman, M. M., Z. Lin, X. Jia, D. D. Steele, and T. M. DeSutter. 2014. Impact of subsurface drainage on streamflows in the Red River of the North basin. Journal of Hydrology 511: 474-483.
- The SARE site was included as a field tour for two, day long drainage water management (DWM) training sessions for Natural Resource Conservation Service (NRCS) personnel. Over 50 NRCS employees visited the site and heard presentations by the project leader, Xinhua Jia, as well as the land owner, Mr. Jerry Zimmerman.
- The SARE site installation and yield results have been and will continue to be used in Drainage Design Workshop presentations by Extension engineers as an example of one method of subirrigation.
- The landowner, Mr. Zimmerman, was a guest presenter at Drainage Design Workshop held in Grand Forks. He provided the farmer/tile installer perspective to the workshop attendees.
Associate Professor and P.E.
North Dakota State University
NDSU Dept 7620, PO Box 6050
Fargo, ND 58108
Office Phone: 7012317268
Associate Professor and Extension Agronomist
North Dakota State University
Dept of Plant Sciences
Fargo, ND 58108
Office Phone: 7012318135
Buffalo-Red River Watershed District
123 Front St. S.
Barnesville, MN 56514
Office Phone: 2183547710
Professor and Extension Engineer
University of Minnesota
1390 Eckles Ave
St. Paul, MN 55108
Office Phone: 6126254756
NDSU Dept. 7680, PO Box 6050
Fargo, ND 58108
Office Phone: 7012318690
Associate Professor and Extension Engineer
NDSU Dept 7620, PO Box 6050
Fargo, ND 58108
Office Phone: 7012317239
Senior Planner on conservation drainage
Minnesota Department of Agriculture
625 Robert St. N
St. Paul, MN 55155
Office Phone: 6512016482
7276 50th St. N.
Glyndon, MN 56547