Irrigation in addition to rainfall drives plant production but also affects soil drainage and thus has a critical influence on leaching and runoff nutrient loss pathways.
5 soil moisture assessment options can be selected in OverseerFM, these are:
- Fixed depth and return period– This has a fixed return period and fixed depth applied. The farmer is making little to know decision on when to irrigate. The irrigation system is operated using a set amount of irrigation applied at regular intervals. Spraylines and travelling irrigators are commonly used in this way.
- Visual assessment/dig a hole - This has a fixed return period and fixed depth applied. The farmer is assessing the soil moisture level in the soil before beginning an irrigation event. Visual observations of the crop and/or soil are made to schedule irrigation.
- Soil Water Budget – A soil water budgets predict the amount of available water stored in the plant root zone. A soil water budget tracks your soil moisture levels with plant water use, rainfall and irrigation applications recorded on a daily basis and the PET (potential evapotranspiration). The budget can be done using a spreadsheet which you personalise for your farm at the start of the season. A soil moisture strategy is required to be selected.
- Soil Moisture sensors:probes/tapes - Soil moisture sensors are used to measure the water content of the soil. There are a variety of sensors available. They fall into two categories – volumetric (measure the water in the soil – how much is available for use by plants)MM deficit, or tension (measure how tightly water is held by the soil – how hard a plant has to work to get it)%PAW. Soil Moisture sensors:probes/tapes are calibrated to individual soil types on the farm and soil moisture graphs are reported back to the farmer. These graphs allow the farmer to make decisions on when to begin irrigating. A soil moisture strategy is required to be selected
- Enter application depth - a total monthly application depth is required to be entered. There is no decision made on when to irrigate.
When Soil Water Budget or Soil Moisture sensors:probes/tapes are selected a soil moisture strategy is required to be selected. Refer to knowledge base article Descriptions of soil moisture strategy to find out more.