Karst rocky desertification control through the conversion of cropland to economic forest is vital for vegetation recovery and the alleviation of distinct contradiction between ecological conservation and economic development. To evaluate the sustainability of orchard systems from the perspectives of ecosystem and economic services, we employed emergy analysis for the comprehensive and quantitative assessment of two orchard system types: (1) mango monoculture (MM) and macadamia monoculture (NM) and (2) mango Vicia angustifolia intercropping (MVI) and macadamia Desmodium intortum intercropping (NDI). In the past, these areas were converted from a maize field (MF) in the southwest karst area of China. Our results showed that, compared to the MF, the total emergy input in monoculture orchards (NM and NM) decreased by 8.99% and 35.25%, and the economic profit (EP) increased by 20,406.57 and 114,406.32 RMB·ha⁻¹, respectively. However, the non-renewable environmental input (energy loss of soil, SOM reduction, and irrigation water) still accounted for 43.25% and 62.01% in the total emergy input. After conversion to orchard legume herb intercropping (MVI and NDI), purchased resource inputs accounted for 86.36% and 68.20% of the total emergy input. Orchard legume herb intercropping further increased the EP, while improving ecosystem services and providing the capability for groundwater recharge, soil conservation, and soil carbon sequestration. The intercropping orchards were relatively sustainable from the view of economic and ecosystem services (EISD > 3.18), due to lower environmental loading ratios (ELR < 1.15), higher emergy yield ratio (EYR > 0.89), and economic output/input ratio (O/I ratio > 2.41). The integrated pest management simulations indicated that, compared to intercropping systems, the renewable percent (R%) and emergy sustainability index (ESI) of the scenario simulations (MVI-O and NDI-O) increased by 17.61% and 10.51%, respectively. These results suggest that integrated pest management is an effective method to improve the short-term sustainability of the orchard system. Therefore, the management of intercropped legume herb within an orchard system is an effective way to achieve sustainable development.

Mangoes are an important part of Hainan’s tropical characteristic agriculture. In response to the requirements of building an ecological civilization pilot demonstration zone in Hainan, China, green and sustainable development will be the future development trend of the mango planting system. However, the economic benefits and environmental impact during its planting and management process remain unclear. This paper combines emergy, life cycle assessment (LCA), and economic analysis to compare the system sustainability, environmental impact, and economic benefits of the traditional mango cultivation system (TM) in Dongfang City, Hainan Province, and the early-maturing mango cultivation system (EM) in Sanya City. The emergy evaluation results show that the total emergy input of EM (1.37 × 10¹⁶ sej ha⁻¹) was higher than that of TM (1.32 × 10¹⁶ sej ha⁻¹). From the perspective of the emergy index, compared with TM, EM exerted less pressure on the local environment and has better stability and sustainability. This was due to the higher input of renewable resources in EM. The LCA results showed that based on mass as the functional unit, the potential environmental impact of the EM is relatively high, and its total environmental impact index was 18.67–33.19% higher than that of the TM. Fertilizer input and On-Farm emissions were the main factors causing environmental consequences. Choosing alternative fertilizers that have a smaller impact on the environment may effectively reduce the environmental impact of the system. The economic analysis results showed that due to the higher selling price of early-maturing mango, the total profit and cost–benefit ratio of the EM have increased by 55.84% and 36.87%, respectively, compared with the TM. These results indicated that EM in Sanya City can enhance environmental sustainability and boost producers’ annual income, but attention should be paid to the negative environmental impact of excessive fertilizer input. These findings offer insights into optimizing agricultural inputs for Hainan mango production to mitigate multiple environmental impacts while enhancing economic benefits, aiming to provide theoretical support for promoting the sustainable development of the Hainan mango industry.

Karst desertification causes severe soil erosion, hydrological imbalance, and biodiversity loss, thereby threatening ecosystem resilience and agricultural productivity. Soil carbon (C), nitrogen (N), phosphorus (P), and sulfur (S) cycling underpin ecosystem stability, yet how agricultural management practices regulate multi-element cycling in degraded karst agroecosystems remains poorly understood. Here, we conducted a four-year field trial in a karst mango orchard in southwestern China and integrated metagenomic sequencing with comprehensive soil environmental profiling to investigate how C. rotundifolia cover cropping reshapes soil elemental cycling. Compared with conventional tillage (CK), C. rotundifolia cover cropping (Y) significantly ( p < 0.05) altered topsoil microbial functional profiles and nutrient availability. Carbon cycling potentials, including gene associated with aerobic respiration ( cox1/3 ), fermentation, and CO₂ assimilation—were enriched under C. rotundifolia cover cropping. Nitrogen cycling potentials were enhanced through increased representation of genes involved in denitrification ( nirK/S , nosZ ), nitrogen acquisition, and nitrate reduction ( nirA , narB ), while phosphorus cycling was promoted through enrichment of the PhoR-PhoB phosphate regulatory system. Sulfur transformation potentials were also altered, with increased representation of genes involved in sulfate reduction, oxidation, and sulfonate utilization. Cover cropping substantially improved soil fertility, increasing SOC (+35.4%), NH ₄ ⁺ -N (+31.8%), TN (+35.1%), and AP (+105.9%), while reducing exchangeable Al ³⁺ concentration by 60.9%. Microbial community restructuring was characterized by decreased Actinobacteriota and Chloroflexota and increased Bacteroidota and Proteobacteria, which exhibited central roles in elemental cycling networks. Mantel analyses identified exchangeable Al ³⁺ as a dominant environmental constraint shaping microbial communities involved in C, N, P, and S cycling. Collectively, these findings demonstrate that C. rotundifolia cover cropping enhances karst soil resilience through a coupled microbial-geochemical pathway, in which improved soil chemical conditions and microbial functional reorganization jointly restore elemental cycling capacity.