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NW Washington | You are probably OK unless you have an unusually high soil pH.
AI Overview
When urea, a common fertilizer, comes into contact with water, it dissolves and undergoes a chemical reaction called hydrolysis, converting into ammonium and then, in some cases, into ammonia, which can be lost to the atmosphere.
Here's a more detailed explanation:
Dissolving and Hydrolysis:
Urea is highly soluble in water, meaning it dissolves readily. Once dissolved, it undergoes hydrolysis, a chemical reaction where water molecules break down the urea molecule.
Formation of Ammonium and Ammonia:
The hydrolysis of urea results in the formation of ammonium ions (NH4+) and, depending on conditions, ammonia (NH3).
Soil pH and Ammonia Loss:
The reaction consumes hydrogen ions (H+), which can cause the soil pH near the fertilizer to rise. If the pH rises above 7, a significant amount of gaseous ammonia can form in soil for a few days following urea application.
Ammonia Volatilization:
Ammonia is a gas and can be lost to the atmosphere through a process called volatilization. This loss is particularly problematic in warm temperatures and with high soil pH.
Urease Enzyme:
The enzyme urease, naturally present in soil, also plays a role in urea hydrolysis.
Factors Affecting Loss:
Several factors can influence urea loss, including soil moisture, temperature, soil pH, and the presence of urease inhibitors.
Examples of Urea Loss:
Light Rain: If urea is applied to wet soil and followed by light rain, the urea can dissolve and undergo hydrolysis quickly, leading to high ammonia loss.
Cold Soils: In cold soils, urea hydrolysis can be slow, but if the soil dries out after urea application, ammonia loss can still occur.
Managing Urea Application:
To minimize urea loss, it's important to:
Apply urea when soil moisture is adequate, but not excessively wet.
Consider using urease inhibitors to slow down the hydrolysis process.
Ensure that urea is incorporated into the soil as quickly as possible after application. | |
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Untreated urea no rain on wheat
