Two new modeling studies highlight significant benefits of perennial cereal crops: they increase soil carbon content and can assist farmers in adapting to climate change.
Researcher Giulia Vico and her colleagues have demonstrated that the loss of organic carbon in soil decreases by at least 38 percent when a farmer chooses to cultivate perennial wheat instead of common (annual) winter wheat. Simultaneously, the soil has higher microbial biomass in perennial wheat cultivation, a crucial factor in maintaining ecological functions in arable land.
- Switching to perennial crops increases the soil's organic carbon content, in particular if the perennial cereal has higher photosynthetic capacity. The benefit is approximately 33 grams per square meter annually. This contributes to maintaining soil carbon levels more similar to those found in grasslands, says Giulia Vico, professor at SLU.
Part of the explanation lies in the deeper roots of perennial wheat, aiding in enhancing the organic carbon content in the soil.
The researchers also assessed how well perennial grain crops withstand future warmer and drier climates. Different varieties of perennial wheat exhibit varying traits influencing their resilience to heat and water stress. Perennial wheat had up to a 39 percent higher water evaporation and carbon uptake compared to common wheat, depending on their photosynthetic capacity and leaf area. When soil water availability is low, the deep rooted perennial wheat can still take up water and thus maintain lower leaf temperatures and higher photosynthesis, compared with common wheat.
- In short, perennial wheat requires more water but can withstand longer dry periods. Plant characteristics, especially leaf area and rooting depth, play a significant role in how well perennial grain crops adapt to warmer and drier climates. This is crucial information to consider when pondering the functionality of these crops under future climatic conditions, summarizes Giulia Vico.
To reach these conclusions, Giulia Vico and her international team of researchers employed models simulating ecological and hydrological processes, and extensive datasets of plant traits, to investigate the accumulation of carbon in the soil through various plant and soil-influencing processes. They scrutinized soil organic matter accumulation and decomposition, microbial growth in the soil, as well as leaf temperature and water and carbon dioxide exchanges.
The capability of perennial crops to accumulate carbon in the soil and withstand heat and water stress adds to their other environmental benefits. Plants do not need to be sown and establish every year, reducing energy usage and mitigating negative environmental impacts from agriculture through reduced tillage and nutrient leaching and by allowing continuous soil cover.
- But we must also consider the still remaining differences in yield between the annual and perennial grain crops, Giulia Vico adds.