Soil moisture monitoring
The increased investment in precision irrigation, coupled with a need for irrigators to be more accountable for their water use, is resulting in increased adoption of soil moisture monitoring. However, irrigators must choose the right monitoring equipment for their soil, land use activities and irrigation system type, and then locate, install and calibrate (if necessary) it correctly. Accessing, managing and understanding the data is also important. The soil moisture monitoring guide has been developed to help irrigators be successful when installing and using soil moisture sensors. It has been divided into three parts -
1. The first covers the technology options available for soil moisture monitoring including their benefits and limitations. It also lists the common sensors available in New Zealand. More detail can be found on the technology options in the soil moisture monitoring methods section of this book.
2. The second covers considerations for installing soil moisture sensors, selecting how many are required, their location, when calibration is necessary, and capturing and understanding the information they produce.
3. The third provides a list of simple questions for irrigators to work through in order to successfully choose, install and use soil moisture sensors.
Understanding soil water
Understanding your soil is critical to irrigation scheduling. Below are some resources to help you understand your soil type and how much water it holds.
Soil profile builder
Soil profile builder is a tool that helps you determine how much water your soil holds.
Soil water budgets
Soil water budgets are a simple low cost method to schedule your irrigation. Inputs (rainfall and irrigation) and outputs (plant water use and any drainage from over irrigation) are recorded as a daily water budget in mm. The soils water holding characteristics define the maximum amount of water that can be stored, again in mm.
Soil water budgets work well for pasture irrigation where the daily Potential Evapotranspiration (PET) can be used as the measure of plant water use. For other crops PET needs to be adjusted by a crop factor, this reflects the crop type and/or growth stage.
IrrigationNZ, Irrigation Essentials and Irrigation Management resource books provide detailed information on understanding soil water, climate measurements for irrigation, plant water use, and how to use these to schedule your irrigation. These are available free to IrrigationNZ members.
Below are a list of commercial water budgeting tools and services available in New Zealand, note soil water budgets are usually used in conjunction with soil moisture monitoring.