*3.3. Soil and Climatic Determinants of Biomass Productivity in Hungary*

In general, humus content (which also reflects organic matter content), pH, CaCO3 content, soil type and soil texture were the most important soil-based input parameters for predicting wheat productivity (Figure 6A). However, the geographical location was found to be an even more important explanatory variable. While this information suggests the importance of climate, the measured climatic variables ranked lower in the importance list. The mean temperatures of January, February, December and June (in the order of importance) are the most important thermal parameters for productivity. Regarding precipitation, the amounts in November, August, June and December are the most important determinants.

In the case of maize, on the other hand, the measured climatic variables were found to be of high importance, together with humus, pH, CaCO3 and soil type, while the location was not considered to be relevant. These differences suggest the appropriateness of the crop-specific evaluation approach. There are also differences in the mean temperature and precipitation. Figure 6B shows that the precipitation (July, November, May, August and October) is a more important factor than temperature (most important in January and February) in the case of maize.

**Figure 6.** Overall importance of explanatory variables in predicting wheat (**A**), maize (**B**) and sunflower (**C**) biomass productivity.

Based on Figure 6C, the variables of the sunflower prediction show a completely different pattern. The most important variables are the location and mean temperature in February, followed by humus content, mean temperature in January, March and November, pH, precipitation in November and CaCO3. Soil type and texture are the least important variables. Climatic variables (mainly amount of precipitation) have a more significant effect on the sunflower yield amount than the soil type and texture.
