Introduction: Soil carbon sequestration capacity in ecologically fragile areas of the Taihang Mountains’ gneiss slopes demands immediate attention. This study evaluated the synergistic effects of land-use transition (from barren hills to cropland to pear orchards) and cover crop intercropping on soil carbon storage. Methods: Field sampling and experiments were conducted at 72 sites in Fuping County. The analysis combined multi-index assessment of soil physicochemical properties with partial least squares structural equation modeling (PLS-SEM). Results: Land-use transition significantly increased soil carbon storage. In 8-year-old pear orchards, the organic carbon storage in the 0-20 cm soil layer reached 26.08 tC/ha, representing a 151.89% increase compared to cultivated land (10.35 tC/ha). Meanwhile, soil carbon storage in the 20-40 cm layer increased by 83.97% to 13.58 tC/ha. Under the cover cropping pattern, ryegrass in the surface 0-20 cm soil of 8-year-old orchards showed an 18.5% improvement in efficiency over natural grass. In the 20-40 cm deep soil, winter rape increased organic carbon content by 22.43% to 10.59 g/kg. Discussion: The synergistic mechanism was attributed to increased carbon input from cover crops and root systems, optimized soil physical structure (bulk density decreased by 5.1%-8.0%, porosity increased by 2.1%-4.1%), and formation of a nutrient-carbon pool synergy. Available potassium, phosphorus, and organic carbon were significantly positively correlated. This pear orchard and cover crop intercropping system exemplifies a practical Nature-based Solutions (NbS) pathway, achieving an annual carbon sink growth rate of 4.2-5.8 tC/(ha·a). Its core mechanism lies in constructing a triple synergy of “carbon sequestration enhancement, structural optimization, and nutrient cycling”, which enhances ecosystem services multidimensionally while fostering a resilient agricultural production system. This practice provides a technical paradigm for synergizing carbon neutrality goals and ecological restoration in fragile mountainous areas.

Melon (Cucumis melo L.) and tomato (Solanum lycopersicum L.) are key horticultural crops cultivated in protected agricultural facilities across North China. Nitrification inhibitors and microbial agents have been used to improve soil available nutrients. However, the effect of nitrification inhibitors and microbial agents on melons and tomatoes is unclear. This study investigated whether five additional treatments using nitrification inhibitors (dicyandiamide, DCD and 3, 4-dimethylpyrazole phosphate, DMPP) or/and microbial agents could enhance soil nutrients, tomato and melon growth, and yield in the tomato–melon rotation system in the North China Plain. The results showed that the combination of DCD and a microbial agent resulted in the lowest concentration of nitrate nitrogen in the soil. In addition, the application of DMPP alongside a microbial agent notably enhanced the plant height and stem diameter of melon, whereas the combination of DCD and a microbial agent led to the greatest plant height and stem diameter in tomato. Both nitrification inhibitors and microbial agents exhibited a markedly positive influence on the melon and tomato yields; among treatments, the co-application of DMPP and microbial agent showed the greatest yield improvement of 21.7% for melon and of 41.5% for tomato, compared to the local fertilization. Furthermore, the co-application of DMPP and microbial agent significantly improved tomato fruit quality with a 65.5% increase in vitamin C content, a 172.2% elevation in sugar-acid ratio, and a 43.5% reduction in nitrate concentration, compared to the local fertilization. In conclusion, nitrification inhibitors with microbial agent could effectively promote the growth and yield of melon and tomato, by regulating the soil available nutrient content and inhibiting the soil nitrogen nitrification.

Construction of a multifactor barrier evaluation system and classification of barrier types for arable land on the northern Huang-Huai-Hai Plain

Phosphorus (P) is vital for the growth of crops, and its absorption efficiency is closely linked to the traits of the plants. Further research is needed to understand how vegetable crops adjust to changes in P availability and how their root morphology and physiology are affected by high P levels in the shoots. In this study, eight Chinese cabbage (Brassica rapa pekinensis) genotypes were grown in a culture room under 0, 25, 50, 100, 150, 300, 600, 900, and 1200 mg kg⁻¹ concentrations of P to evaluate root responses in order to define various adaptive strategies in relation to P acquisition. We selected high-PE and low-PE Chinese cabbage in order to identify how different P efficiency groups responded to P supply and shoot P concentration. P supply level and shoot P concentration significantly affected growth. With the increase in the P supply level, the growth variable characteristics of Chinese cabbage first increased and then decreased or increased first and then stabilized. But it was found that P300 was the most suitable level for Chinese cabbage growth. At the same P supply level, high-PE cabbages had higher shoot dry weight and P absorption capacity, stronger root traits, and higher plasticity as compared to low-PE cabbages. The optimal shoot P concentration is 2.1 mg g⁻¹ and 1.7 mg g⁻¹ for low- and high-PE cabbages, respectively. The root morphological traits performed greatly when the shoot P concentration was at the optimal concentration. The low-PE cabbages had greater shoot growth traits, and high-PE cabbages had higher root dry weight and P absorption. This study offers valuable insights to improve P management by analyzing the relationships between soil P dynamics and root processes in the cultivation of Chinese cabbage.