Certified Landscape Irrigation Auditor

What is one key feature of net precipitation rate?

1. It is always higher than gross PR

2. It considers the actual water availability to plants

3. It includes runoff calculations

4. It is measured in gallons per hour

The correct answer is: It considers the actual water availability to plants

Net precipitation rate is defined as the amount of water that is effectively available to plants after accounting for various losses. This key feature is significant because it reflects the actual moisture that reaches the root zone of plants, which directly influences plant health and growth. When assessing irrigation systems, understanding the net precipitation rate helps determine whether plants are receiving adequate water as intended. It takes into consideration factors such as evaporation, runoff, and deep percolation, providing a clearer picture of how much water is truly available for plant use. While the other options touch on related concepts, they do not accurately describe this key feature. For instance, the gross precipitation rate includes all water applied regardless of losses, while runoff calculations are a factor in determining net precipitation but not part of its definition. Additionally, although measurements in gallons per hour might apply to water flow, they do not specifically define net precipitation rate, which is typically expressed in inches per hour or similar units to reflect depth effectively available to plants.