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. Nineteen irrigated corn farmers and one irrigated soybean farmer expressed interest in evaluating remotely read, soil moisture monitoring equipment for the 2013 season. 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 20 cooperator fields in late May and early June. 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. 2013 proved to be an extremely wet growing season in Delaware especially during the critical corn irrigation periods in June and July. 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 20 cooperator representing 11,340 irrigated acres, over ¾ responded in post season survey that they either planned to purchase or were researching the costs of utilizing soil moisture equipment for managing irrigation in 2014.

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 2013)
   1. Milestone achieved March 2013. This project was delayed 1 year from its initial start date as the funds did not arrive in time to have the soil moisture equipment manufactured for the 2012 growing season.
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 2013)
   1. Milestone achieved April – September 2013
3. Four Hundred growers will receive invitations to attend irrigation workshops at Delaware Ag Week. (November 2013)
   1. Over five hundred invitations to attend the irrigation session at Delaware Ag Week were sent the week of December 1, 2013
4. Two hundred and fifty producers with center pivot irrigation will attend irrigation management workshops that discuss the findings of the 2013 field research/demonstration. (December 2013 – January 2014)
   1. While an irrigation management session will be held at Delaware Ag Week on January 14^th, 2014, the result of the 2013 field research/demonstration will not be presented due to the extraordinarily wet growing season. The 2013 season was so extremely wet that very little irrigation was needed, in fact saturated soil severely limited corn yields by anywhere from 10 – 35% for many of the cooperators. This was a very atypical year and the soil moisture equipment was of little to no use to the cooperators.
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 2014 & 2015)
   1. In progress. 6 producers have expressed interest and have agreed to participate at the writing of this report.
6. Four Hundred growers will receive invitations to attend irrigation workshops at Delaware Ag Week. (November 2013 & 2014)
7. Two hundred producers per year with center pivot irrigation will attend irrigation management workshops that discuss the findings of the 2013 & 2014 field research. (December 2013 – January 2014)
8. Forty-five growers representing nine thousand acres will adopt soil moisture monitoring to manage irrigation. (2014 growing season)

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)

• To date, 20 irrigators representing 11,304 irrigated corn acres have participated in this project, with only 1 reporting an increase in yield as a result of participating. Most growers saw their irrigated yields drop due to an overly wet growing season.

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.

• All 20 cooperators reported a reduction in applied irrigation of over 10” this season as a result of repeated rainfall. The sensors had virtually no effect on the irrigation schedule in the 2013 season.

Accomplishments/Milestones

There was overwhelming interest in participating in this project, especially from corn producers. Several farmers wanted to participate in 2013 but were put on the 2014 list due to the limited amount of equipment (20 fields) for use each year. The initial grower interviews went smoothly and the farmer’s goals were in line with the goals of the project. We were surprised by the number of farmers (9) that already use some sort of soil moisture determination to schedule irrigation and attribute this to the tendency of those interested in participating having already attempted to use soil moisture in the past.

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.

Initially the equipment failure rate was much higher than we had experienced in the past. Upon investigation, it was discovered that a critical seal on the antenna jack of each data logging receiver was incorrectly installed and had allowed water to enter the circuitry resulting in a receiver failure. Once the seal issue was rectified the equipment worked well with the exception of the destruction of 1 transmitter by a lighting strike.

Most of the farmers had no difficulty accessing a utilizing the data with only 3 requiring one on one consultation. Just as the farmers were beginning to get comfortable with the equipment and its value for irrigation scheduling, the weather turned extremely wet and remained so throughout the corn vegetative, reproductive and grain fill stages. Little to no irrigation occurred during the typical peak corn irrigation time period of mid-June through all of July.

The equipment was removed in early September, just prior to harvest and the post season surveys of each cooperator were conducted. Many of the growers expressed disappointment that they would not be able to use the equipment again next year as they felt that there was great potential for improving their individual irrigation schedules but the 2013 season was too wet for them to get the full experience.

Impacts and Contributions/Outcomes

In the post season survey, 6 of the 20 cooperators responded that they plan to purchase soil moisture equipment to help them manage their irrigation in the 2014 season. Another 11 responded that they might purchase the equipment if it is affordable and reliable. Only 3 farmers responded that they would not consider purchasing any soil moisture equipment.

 While 16 of the participating farmers saw similar or reduced yields from previous years, all of those attributed the yield reduction to excessive rainfall and nitrogen loss. Despite the poor crop year, 8 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 17 of the 20 participants responded with “nothing”, the other 3 answered “keep the equipment working”, “calibrate the irrigation system”, and “need more help setting up the web service” (it should be noted that this cooperator did not own a computer or smart phone and traveled to the local library to view his data online).

The overall feeling of the 2013 cooperators was that they wished they could use the equipment again in 2014 so they can experience firsthand how to implement soil moisture into their irrigation schedule in a more representative season. We have been contacted by several farmers wishing to participate in 2014 who learned of the program from word of mouth.

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