Legume-forage wheat rotations synergistically enhance soil multifunctionality and economic benefits in dryland agriculture: insights from a 39-year field study

Soil multifunctionality (SMF) is critical for sustaining ecosystem functions. Crop rotations are widely recognized for enhancing soil supporting and provisioning services. However, the trade-offs between these services, and the mechanisms by which long-term rotations improve SMF, remain unclear. To address this gap, we evaluated SMF in both topsoil and subsoil, as well as crop yields and economic benefits, after 39 years of contrasting crop rotation systems in dryland farmland. Our results showed that incorporating legume-based crops, particularly legume forages such as sainfoin and alfalfa, significantly increased SMF in both topsoil and subsoil (p < 0.05). Nevertheless, distinct trade-offs and synergies between economic benefits and soil functions were observed among different rotation patterns. Although cereal-based rotations produced higher short-term economic benefits, they contributed little to soil function improvement. In contrast, well-designed legume forage-based rotations promoted concurrent improvement in SMF and economic benefit. Moreover, soil carbon and nutrient cycling emerged as key drivers of SMF under long-term rotation, with strong implications for economic sustainability. Overall, our findings demonstrate that long-term crop rotation, primarily through enhanced soil nutrient availability, improves both SMF and economic benefit. Integrating forage legume-based crops into wheat rotation represents an effective strategy for strengthening soil supporting services and provisioning economic benefits in dryland agroecosystems.