How to Model Plant Available Water

The amount of plant available water in a soil system plays a fundamental role in determining plant growth, fertilizer requirements, and irrigation scheduling. Modeling plant available water enables agronomists and farmers to estimate how much water crops can access from the soil and how much water plants require for optimal growth. In this article, we will discuss the steps and factors necessary to model plant available water in a soil system accurately.

Step 1: Collect Soil Data

The foundation of modeling plant available water lies in collecting accurate soil data. Soil data help agronomists categorize a soil type based on texture, organic matter content, bulk density, and water-holding capacity. Soil data provide the necessary context to understand the soil-water balance and how water moves through the soil. Accurate soil data also ensure that the model's output is closer to the actual field conditions. Field researchers can use various soil sampling techniques and instruments to collect soil data.

Step 2: Determine Water-Holding Capacity

The water-holding capacity of a soil system refers to the maximum amount of water that a soil can retain after drainage. The available water in a soil system equals the difference between the water-holding capacity and the wilting point. The wilting point is when plants can no longer extract water from the soil. Soil scientists classify soil moisture into three categories; field capacity, permanent wilting point, and deficit. Scientists can use laboratory tests to determine the soil's water-holding capacity, plant available water, and other soil properties.

Step 3: Account for Climate and Weather Effects

Climatic conditions and weather events significantly influence the soil's water content and, consequently, plant growth. Higher temperatures increase water loss through evaporation, transpiration, and soil evaporation. Precipitation and infiltration rates are also affected by the weather. Modeling plant available water requires accounting for the effects of weather and climatic conditions on the soil's water balance. Researchers can use meteorological datasets and weather models to estimate the soil's moisture and predict future weather patterns.

Step 4: Incorporate Crop Water Requirements

Modeling plant available water alone is not sufficient for optimizing crop growth. The model should account for the water requirements of the specific crops grown in the field. Different crops have varying water requirements depending on their stage of growth. The plant's root system and the soil's water-holding capacity also influence plant water requirements. Modeling crop water requirements will help farmers schedule irrigation, reduce water waste, and improve crop yield.

Step 5: Validate the Model's Output

After collecting and inputting all the necessary data into the model, it is essential to validate its output. Validation ensures that the model's output is closer to the actual field conditions. Agronomists can perform field trials and comparisons to check the model's accuracy. Field trials involve measuring the soil and plant conditions, including soil moisture and crop yield. Comparisons involve using different models to predict the same field conditions and comparing their outputs.

Conclusion

In summary, modeling plant available water requires collecting accurate soil data, determining the water-holding capacity, accounting for weather and climatic effects, incorporating crop water requirements, and validating the model's output. Accurately modeling plant available water enables farmers to optimize crop growth, reduce water wastage, and increase crop yield. The model's accuracy ensures that farmers make informed decisions based on reliable predictions without underestimating or overestimating crop water requirements.