Estimate of Mineralized Organic Nitrogen in Soil Using Nitrogen Balances and Determining Available Nitrogen by the Electro-ultrafiltration Technique. Application to Mediterranean Climate Soils

To be able to optimize the nitrogenous fertilizer rate applied to agricultural crops, the soil's available N must be known, particularly that provided by the organic matter's N mineralization. The methodology proposed to achieve this aim is based on determining the soil's mineral N balance. Many parameters were controlled in this endeavor: mineral N content at three depths (0−30, 30−70, and 70−140 cm), crop absorbed N, leached N and the soil's moisture content. A mineral N balance was established for two types of crop with different cycles: winter cereal (wheat) and spring−summer cereal (maize). Two irrigation systems were also compared. This method enabled the mineralized N to be accurately estimated. It likewise enabled a formula for estimating available N based on the EUF technique.