SR Model Irrometer Soil Moisture Meter in various lengths.

Perhaps the most important soil moisture reading is the difference between today's reading and that of 3 – 5 days ago. That is to say, how quickly is the reading going up? A slow increase means the soil is drying out slowly. But a big jump means the soil is losing water very rapidly. By analyzing such trends in the readings, you will determine WHEN to irrigate. A graph of readings over time makes it easier to see the trends, thereby making interpretation simpler. Your own situation may be unique because of differences in crop, soils and climate.

By using sensors at two or more depths in the root system, you can determine HOW MUCH water to apply. If the shallow sensor shows a rapidly increasing reading, but the deep sensor shows adequate moisture, you can run a short irrigation cycle as you only need to replenish the shallow root profile. If the deep sensor also shows a dry condition, then a longer irrigation cycle is needed to fully re-wet the entire root zone. The readings you take after an irrigation or rainfall event will show you exactly how effective that water application was.

Your own experience and management will soon point you in the proper direction. You will be practicing irrigation to achieve the positive results that come from any good management program.