Irrigation New Zealand

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.

It is important to choose the right equipment for soil, land use, system type, and, and then locate, install, and calibrate (if necessary) it correctly. Accessing, managing, and understanding the data is also important. The soil moisture monitoring guide is 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.

Soil water budget spreadsheet

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.

IrrigationNZ Irrigation Essentials

Irrigation Management