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Available Water in Soil Calculator


Instructions for Available Water Calculation:

1. Enter the contents of Total Sand, Silt and Clay in your soil. Data must be entered as a percentage, without decimals, and the sum of the three components must total 100%.
2. If you have separate values for Coarse Sand and Fine Sand, add these values and enter the result in the "Total Sand" field.
3. The calculator will automatically perform the calculation of Available Water (AD) estimated in mm/cm based on the data provided, according to the predictive equation presented in Teixeixa et al., 2021.
4. Based on the Predicted AD value, the calculator will automatically classify the soil into one of the ZARC AD classes. ZARC AD classes are defined according to the criteria established in Normative Instruction No. 01 of July 22, 2022.

Available Water (AD) Classification Table for Agricultural Climate Risk Zoning (ZARC) in Brazil:

The following table presents the Available Water (AD) classification based on the range of values between 0.34 mm cm-1 to 1.84 mm cm-1, subdivided into six classes. This classification is used for the assessment of water deficit risk in the context of Agricultural Climate Risk Zoning (ZARC) in Brazil. It plays an essential role in determining the planting period and adequate crop management according to soil conditions.

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Frequently Asked Questions about ZARC and Soil Classification Change

  • What is Available Water in Soil Class (AD)?

    Available Water in Soil Class (AD) is a fundamental attribute for agriculture, indicating the amount of water that can be stored in the soil and used by plants. The higher the AD, the greater the soil's ability to provide water to plants during periods without rain, contributing to the success of agricultural crops.

  • Why is Available Water in Soil (AD) classification important for ZARC?

    Agricultural Climate Risk Zoning (ZARC) uses AD classification to determine the best planting period and mitigate risks of production losses due to climate adversities.