Nitrogen nutrition status of plants can be assessed either by direct or indirect tests. Direct tests consist in determination of total-N content in plant dry matter or N-O₃ content in green, indicator organs of the plants. Activity of nitrate reductase as well as the chlorophyll content in leaves are measured by indirect tests. Recently a fast and non-destructive chlorophyll measurement test with SPAD application is becoming more and more important.
The method of soil tillage affects maize yielding and causes the changes in chemical and physical soil properties. Application of reduced soil tillage, and the zero-tillage in particular, over many years usually results in reduction of the maize yields and unfavourably influence the most of studied soil properties, especially in the upper soil layer. The correct planting procedure assuring the optimum plant density as well as exact weed control are two most important factors leading to success at reduced soil tillage, particularly zero tillage, application.