Hi Farmers,

We’ve had a few questions about managing soil moisture this year, so thought we’d post the following information (although right now you don’t need any equipment to tell you that it is very, very dry).  Hope you all can sneak in a swim today.

For more information on soil moisture monitoring, contact Joshua Faulkner ([log in to unmask]) or Becky Maden ([log in to unmask]).  

 

Soil moisture monitoring for irrigation efficiency

Submitted by Joshua Faulkner, Rachel Schattman, Becky Maden, and Haley Jean

 

Irrigation is hard to keep up with, especially in a hot, dry year like this one. Soil moisture monitoring is one way to help prioritize which crops to water, how much water to apply, and when to apply it. There are a few options when it comes to soil moisture monitoring. If you want to keep your approach simple and low cost, we suggest that you measure in only a few locations. Prioritizing high-value crops and easily-irrigated parts of your farm makes the most sense.

 

What equipment do you need to get started with soil moisture monitoring? A good place to start is a standby tensiometer (the version made by Irrometer is available from several regions suppliers). For most vegetable crops, a shallow 12” tensiometer will allow you to measure at or near the root zone. It should be noted that these units take some calibration and maintenance, and should not be left in the fields over the winter. (The clay tip will crack.) If you prefer equipment that is low maintenance and will give you a digital read-out, you could try Watermark sensors (sold by many regional suppliers). These units can be left in the field over the winter, and are a low-cost investment. If you use Watermark sensors, you will need to also purchase a handheld readout unit. Joshua Faulkner (UVM) and Rachel Schattman (UMaine) have trialled both the tensiometer and the Watermark options on Vermont farms, and have been pleased with the results. 

 

If you are looking for a moisture monitoring system that gives you continuous readings and you have the patience to set up a more elaborate system, there are several web- or cellular-based options available to you. These types of approaches are higher cost, and can be challenging to set up. However, they allow you to more closely monitor your crops, and may be appropriate for high-value plantings. Read outs are cloud-based, and you can access them from a computer, tablet, or smartphone.

 

What do you do with your soil moisture data once you get it? The upper and lower thresholds for irrigation scheduling vary depending on the soil texture. While there are general guides available (https://www.irrometer.com/basics.html) about what soil moisture levels are optimal for plant growth, you will need to fine tune this guidance with your own knowledge of your soils.

  

Resources:

  1. UVM Drip Irrigation Fact Sheet: https://www.uvm.edu/climatefarming/sites/default/files/files/uvm_dripirrigation.pdf
  2. UNH Soil Moisture Sensor Fact Sheet: https://extension.unh.edu/resource/soil-moisture-sensors-fact-sheet
  3. On-going NE-SARE funded soil moisture sensor experiment at UVM/UMaine: https://projects.sare.org/project-reports/lne19-391r/
  4. Irrometer sensors: https://www.irrometer.com/sensors.html#irro