Popular Science: Do we know how newly introduced cultural crops are influencing the soil?
We are used to producing oilseed rape, Miscanthus and hybrid sorrel (Rumex patientia x R. tianshanicus) as biofuel plants. While the first two crops are already established in our country, we have very little information so far about the effects of the long-term cultivation of hybrid sorrel on soil organisms.
If the fields are correctly positioned, designed and managed, it can reduce the level of nutrient leaching from the soil and soil erosion and provide additional ecosystem services such as carbon sequestration, improving soil fertility and the removal of toxic substances from soil or waste. However, whether the final effect on the diversity of soil organisms will be positive or negative depends on many production factors of these crops. Some of the recently introduced crops for biofuel production can contribute to the faster degradation of soil and deepen problems with biological invasions, where introduced plants are spreading uncontrolled outside cultivation areas and outcompete native species.
The main aim of the research group of scientists from various institutions, including the Institute of Environmental Studies and the Department of Ecology of Charles University, was to assess the potential positive and negative environmental effects of long-term cultivation of hybrid sorrel, the new crop planned to be used for biofuel production.
Hybrid sorrel is an advantageous crop in several respects – it can be harvested in a dry state, achieves high yields for more than ten years and tolerates a wide range of soil types, methods of fertilization and climatic conditions. The catch is that some species of sorrel have been the cause of much interest among scientists engaged in biological invasions and have become a hot topic in this field. For the above reasons, hybrid sorrel is potentially a dangerous crop.
The authors compared several types of fields – two-year-old and more than ten-year-old sorrel fields, oilseed rape/wheat field under ten years and a cultural meadow of bluegrass, clover, plantain, cocksfoot and foxtail. Unlike the other two fields, more fungi pathogenic to plants occurred in the field soil with the ten-year-old sorrel, which is in line with results already obtained in other studies. Most meso- and macrofauna revelled in the meadow and sorrel soil; the soil of the oilseed rape/wheat field was slightly less alive. Authors attributed these results to the influence of tillage, which generally reduces the diversity of soil fauna. Regarding soil respiration, an indicator of soil microorganism activity, the highest levels were achieved in the oilseed rape/wheat field, the other biotopes didn’t differ much among each other. Here it is again possible to seek the cause of the tillage, which supports both the activity of microbiota and the mineralisation of soil organic matter.
We can summarise that the long-term cultivation of sorrel changes the composition of the soil community, but within the boundaries already observed in other types of habitats. However, it will be necessary to focus on the increased incidence of pathogenic fungi in soil which has been recorded in sorrel fields. This fact may, in the long term, present an advantage for this species because pathogens primarily attack the original plant species.
Heděnec, P., Novotný, D., Usťak, S., Honzík, R., Váňa, D., Petříková, V., Frouz, J. (2015). Effect of long-term cropping hybrid sorrel (Rumex patientia x Rumex tianshanicus) on soil biota. Biomass and Bioenergy 78: 92-98.