Soil and crop management and biomass removal effects on soil organic matter content in Hungary

Greater use of biomass for bioenergy has increased the need to evaluate above ground biomass removal (BR) effects on soil quality components, especially soil organic matter (SOM). A multifactor, 40 year field experiment was conducted in Kompolt, Hungary on a carbonate-free, slightly acidic chernozem brown forest soil (USDA: Ustolls) with the objective of determining the effect of different management systems with concurrent removal of the above ground biomass on the SOM content of the 0-320 mm layer. A multifactor experiment composed of treatments involving different crop rotation (CR), beef manure application, mineral fertiliser application, above ground BR (vs. biomass incorporation, BI) and lucerne management options for different rotations are the basis of this study. CR had no significant effect on SOM content. Management options that included a four year lucerne stand produced significantly higher SOM content in five out of six fertiliser and biomass management combinations. Continuous manure applications and manure + NPK fertiliser resulted in a significantly greater SOM content than management options that minimised or eliminated fertiliser or manure additions. SOM content for different soil amendments and biomass treatments ranked: BR < NPK + BR < BI < manure + BR = NPK + manure + BR with SOM contents of 2.75 < 2.82 < 2.87 < 2.92 per cent (w/w) respectively. Manure had the most profound effect because its significance was most consistent across a range of management combinations and years. The results suggest that agricultural management systems that include lucerne and manure application have the potential to sustain SOM content with concurrent above ground BR in continental climates on Ustolls with near level topography.