A recent study conducted by the Institute of Applied Ecology, Chinese Academy of Sciences (CAS), has made a breakthrough in understanding the biological mechanisms behind the challenges posed by long-term continuous cropping. Published in the journal Geoderma, the study sheds new light on how soil health deteriorates over time when the same crop is repeatedly grown in the same field.

Continuous monocropping has been linked to soil degradation, nutrient imbalances, and declining crop yields. However, the biological mechanisms driving these issues have remained largely unexplored.

The CAS research team focused on soil nematodes—tiny worms that play a crucial role in soil ecosystems. By analyzing the carbon flow within soil nematode food webs in peanut fields subjected to varying durations of continuous cropping, the researchers discovered that as the years of continuous cropping increased, the diversity of soil nematodes declined. Concurrently, the relative abundance of plant-parasitic nematodes soared, while beneficial nematodes that feed on bacteria and fungi (microbivorous nematodes) decreased.

These changes in the nematode community disrupted the balance of carbon flow within the soil food web. The researchers found that the uniformity of carbon flow—defined as how evenly carbon is distributed among different components of the soil food chain—was significantly lower in fields with longer histories of continuous cropping. This disruption in carbon flow is believed to contribute to the decline in soil health and crop productivity.

"Our findings suggest that the buildup of plant-parasitic nematodes and the subsequent disruption of the soil food web are key factors driving the negative impacts of continuous cropping," said Dr. ZHANG Xiaoke, the corresponding author.

By understanding these mechanisms, we can develop more effective strategies to mitigate the problems associated with continuous cropping and promote sustainable agriculture. For example, farmers can help to maintain soil health and improve crop yields by implementing crop rotation and introducing beneficial nematodes to control pests.