Improving water and nitrogen use efficiency using soil moisture monitoring to improve irrigation management

Improving water and nitrogen use efficiency using soil moisture monitoring to improve irrigation management

Summary

Recent advances in soil moisture monitoring equipment have made it economically feasible for irrigated grain producers to utilize this technology to improve yields and utilize water more efficiently. Fourteen irrigated corn farmers and one soybean farmer expressed interest in evaluating remotely read, soil moisture monitoring equipment for the 2015 season. Unlike previous years, the growers that participated were small farmers with relatively few irrigated acres. In many cases the farmer’s time was at a premium thus limiting their ability to take full advantage of the equipment. Each farmer was surveyed in person prior to the growing season to determine their individual growing/irrigation practices and historical yields, water and nitrogen use.

A Watermark 950T/R wireless soil moisture system was installed in each of 15 cooperator fields in late May and early June. This project was initially designed to maintain soil moisture systems in 20 fields however gradual equipment failure and the inability to repair an obsolete system reduced available equipment to just 15. One on one trainings were conducted to familiarize the farmers with the web based reporting service and how to interpret the data gleaned. The equipment was maintained by University of Delaware personnel who also kept in weekly contact with the cooperators to ensure that they could access and understand the soil moisture readings. 2015 proved to be a good growing season in Delaware with timely and adequate rainfall for June and early July. Late July required some irrigation but the heat stress was not high. The sensors were removed just prior to harvest and each cooperator was interviewed individually to determine the successes and failures of the equipment, data interpretation, ease of implementation into the irrigation schedule and overall usefulness of the project.

Of the 15 cooperators representing 3,680 irrigated acres, only 2 farmers representing 180 acres responded in post season survey that they planned to purchase soil moisture equipment. Another 3 responded that they were interested in the equipment but were concerned about the cost and their ability to interpret data.

Objectives/Performance Targets

1. Twenty irrigated corn and soybean producers will be selected by the project team for the demonstration of the field monitoring equipment. (May 2014)

2. Each cooperator will be trained on a one on one basis to access their soil moisture status via the internet, analyze the data and modify their irrigation schedule to address crop needs. Growers will become proficient in interpreting soil moisture data into irrigation recommendations through frequent communication with the research team in the form of site visits, phone, and email contact. (May – Aug 2014)

3. Four Hundred growers will receive invitations to attend irrigation workshops at Delaware Ag Week. (November 2014)

4. Two hundred and fifty producers with center pivot irrigation will attend irrigation management workshops that discuss the findings of the 2014 field research/demonstration. (December 2014 – January 2015)

5. Twenty new producers will be selected by the project team for the demonstration of the field monitoring equipment based on interest they expressed at the winter meetings. (May 2015)

6. Four Hundred growers will receive invitations to attend irrigation workshops at Delaware Ag Week. (November 2015)

7. Two hundred producers per year with center pivot irrigation will attend irrigation management workshops that discuss the findings of the 2013, 2014 & 2015 field research. (December 2015 – January 2016)

8. Forty-five growers representing nine thousand acres will adopt soil moisture monitoring to manage irrigation. (2015 growing season)

9. Thirty-four irrigators representing sixty nine hundred acres will improve their irrigation scheduling on 6,900 acres of corn to improve yields by 15 bu/acre ($621,000/year) and increase nitrogen use efficiency from 1 lb applied per harvested bushel to 0.95 lbs/bu. An additional 14 irrigators will improve soybean irrigation on 2800 acres by 5 bu/acre ($182,000 per year)

10. Twelve of these thirty four irrigators will reduce their overall irrigation application by two inches per year over twenty-five hundred acres, resulting in a five percent increase in yield (approximately $110,000/year), $20 per acre reduction in pumping costs ($50,000/year) and 135 million gallons in conserved water.

Accomplishments/Milestones

Unlike 2013 and 2014, there was only limited interest in participating in this project. The limited interest is likely a combination of most looking to adopt a soil mositure program participated in 2013 & 2014 and the limited success reported from previous years. The initial grower interviews went smoothly and the farmer’s goals were in line with the goals of the project.

The soil moisture equipment installation went as planned, and 4 monitoring stations were installed in each field with one station in both the lightest/highest soil and the heaviest/lowest soil and 2 stations in the most predominate soil type. Each station monitored soil moisture levels at 6”, 12” and 18” below the soil surface and wirelessly transmitted the data back to a central data logging receiver approximately 10 to 15 times per day. The combined data from each of the 4 stations could be viewed real time by each cooperator on the internet.

As we have become more familiar with the maintenance and operation of this equipment the failure rate has been greatly reduced. The extra steps taken to minimize moisture in the boxes, and new sensor installation methods for fine textured soils have significantly improved reliability. Despite our best efforts 5 units (mostly the very specific modems failed and were unable to be repaired)

In many cases the growers simply didn’t care enough to look at the soil moisture data on the web despite the sometimes excessive hand holding. Additionally, the relatively timely rainfall gave the growers a high sense of security the crop would be fine without micromanaging irrigation.

The equipment was removed in early September, just prior to harvest and the post season surveys of each cooperator were conducted. Several growers expressed their opinion that the sensors provided more value for determining when to start irrigating after a major rain event than for daily management.

Impacts and Contributions/Outcomes

In the post season survey, 2 of the 15 cooperators responded that they plan to purchase soil moisture equipment to help them manage their irrigation in the 2015 season. Another 3 responded that they might purchase the equipment if it is affordable and reliable. 8 farmers answered that they would not consider purchasing any soil moisture equipment.

While 3 of the 15 participants indicated that the saw increased yields, none attributed the yield increase to refined irrigation management with the sensors. Most of the cooperators used the soil moisture system to test their own method of scheduling. Unfortunately, the mild summer likely exaggerated the adequacy of their methods. 6 farmers responded that they plan to make changes to their irrigation schedule as a result of this project. Overall, when asked what could be done to improve this project 11 participants responded with “nothing” and 1 recommended that a better explanation of how to read the graphs was needed.

The overall feeling of the 2015 cooperators was that they already do a good job irrigating using personal experience and the time required to install and maintain the equipment plus the initial cost would not bring adequate value to their operation.

• Season long soil moisture report graphs for growers
• Pre & Post Project Survey Summary

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