Excessive use of chemical fertilizers in agriculture has become a major global source of pollution, leading to issues such as soil compaction, reduced fertility, eutrophication of water bodies, and air pollution. To address these challenges, the application of biofertilizers, such as rhizobial inoculants, has gradually become an effective, low-cost, and sustainable solution. In this study, the variety Trifolium ambiguum Bieb. (Mengnong clover No. 1) was used as the test material, and two rhizobial strains (R1 and R2) were employed for field inoculation trials. In April 2022, Caucasian clover was planted in an experimental field at Inner Mongolia Agricultural University. Each plot measured 3 m × 4 m and was arranged in a completely randomized design with three replications. In the regreening stage of 2023, rhizobial inoculation treatments were applied, with a control group included for comparison. This research examined the effects of rhizobial inoculation on the growth indicators of Caucasian clover, soil physicochemical properties, soil enzyme activities, and soil microbial communities. The results showed that rhizobial treatment increased the plant height and yield of Caucasian clover, improved soil physicochemical properties and enzyme activities, and positively affected soil microbial diversity and abundance. These changes enhanced soil fertility and optimized microbial community structure, promoting plant growth. The inoculation effect of strain R1 was superior to R2. In conclusion, rhizobial inoculants R1 and R2 can serve as effective biofertilizers for agricultural production.

The biogeophysical effects of land cover change (LCC) on land surface temperature are largely understood, especially in tropical and boreal zones, but fewer studies have reported the biogeophysical consequences of ecological restoration of mining areas located in arid and semi-arid temperate zones. In this study, we employed 2000–2015 satellite-based net radiation (Rn) and latent heat flux (LE) data from mining areas (taking Dongsheng in Inner Mongolia as an example) and adjacent ecological restoration areas to understand the biogeophysical effect of revegetation around mining areas. The results showed that revegetation increased Rn (0.25 ± 0.17 W/m²) and LE (0.43 ± 0.26 W/m²). The warming effect of increased Rn (∆Rn), however, was completely offset by the cooling effect of increased LE (∆LE), thus revegetation caused an overall cooling effect of −0.18 ± 0.17 W/m². Land surface temperature (LST) from mining areas and adjacent ecological restoration areas also showed that revegetation decreased LST (∆LST being −0.2 ± 0.1 K). The difference of ∆Rn and ∆LE explained 27% of the ∆LST variations. These findings reinforce our understanding for the potential climatic benefits of the ecological restoration around mining areas in arid and semi-arid temperate zones.

Breeding new high-yield and high-quality forage soybean cultivars is an effective approach to addressing the shortage of feed protein and sustainable agricultural development. Plant height is a key indicator of forage soybean genotypes and is closely related to forage yield. However, the determinants affecting soybean plant height remain highly uncertain. In order to analyze the factors contributing to plant height differences among soybean cultivars, two tall-stemmed soybean cultivars (“Neinong S001” and “Neinong S002”) and two short-stemmed soybean cultivars (“Neinong 0004” and “Neinong 0005”) were used in this study as test materials for examining aboveground phenotypic characteristics, root traits, and photosynthetic characteristics. The test materials were planted in 2018 at Chakintai Ranch (122°15′ E, 43°38′ N) using the potting method, and the indicators were measured in June. The results showed that the leaf area, root volume, and root surface area of high-stemmed soybean cultivars were significantly (p < 0.05) lower than those of short-stemmed soybean cultivars. Additionally, the dry weight of a single plant and transpiration rate were significantly (p < 0.05) higher in high-stemmed soybean cultivars compared to short-stemmed soybean cultivars. It was found that soybean plant height was significantly (p < 0.05) correlated with leaf area, leaf shape index, intercellular CO₂ concentration, transpiration rate, SPAD, root weight, root length, root surface area, and root volume. Further path analyses revealed that intercellular CO₂ concentration and root surface area had a direct impact on plant height, with direct effect coefficients of 0.22 and −0.91, respectively. These results provide new insights into the sustainability development and genetic enhancement of plant height characteristics in forage soybean.

Caucasian clover (Trifolium ambiguum) is a perennial rooted and tillering leguminous forage with strong adaptability, outstanding stress tolerance and other preferable traits. However, the specificity with rhizobia limits the extended application of Caucasian clover. Therefore, it is important to study the changes of genes and metabolites in the early process of nodulation in Caucasian clover to improve its nodulation and nitrogen fixation ability. In this study, we used Caucasian clover as the experimental material to investigate its nodulation mechanism using transcriptomic and metabolomic approaches, such that to break the nitrogen fixation barrier for the promotion of Caucasian clover. Metabolomic and transcriptomic profiling revealed that both DAMs and DEGs were significantly enriched in the phenylpropanoid and flavonoid biosynthetic pathways, with DEGs showing up-regulation at 3 days and 6 days post inoculation (dpi) with rhizobia, and some DEGs showing down-regulation at 9 dpi. Accumulation of flavonoids was significantly increased at both 3 dpi and 6 dpi, and some compounds were significantly decreased at 9 dpi. A total of 35 DEGs were involved in flavonoid synthesis by WGCNA analysis, among which HCT, CCR, COMT and F3H played an important role. This study provides insights in understanding the molecular mechanism of nodulation and nitrogen fixation in Caucasian clover.

The study of soil environment in drainage fields is important for environmental management and ecological restoration, and there is currently a knowledge gap in understanding the impact of soil microbial communities in the Shengli coalfield drainage fields and the corresponding ecological effects. To investigate the changes in rhizosphere soil microbial communities of different dominant plants after years of restoration, this study examines the improvement effects of different dominant plants on the soil environment. This study is based on high-throughput sequencing to restore the slope of coal mine spoil after 15 years as the sampling site. The rhizosphere soil of five dominant plants was selected for microbial community analysis, and functional prediction of the microbial community was conducted. The dominant plants selected included Erect Milkvetch (Astragalus adsurgens), Lemongrass (Caragana korshinskii), Alfalfa (Medicago sativa), Phyllanthus pinnatifida (Elymus dahuricus), and Brassica Rapa (Brassica campestris). The results showed that after 15 years of restoration, the soil physicochemical properties in the Phyllanthus pinnatifida group were better than those in the other groups overall, but some of them were inferior to those in the lemon-stripped mallard group. Abundant saprophytic fungal communities were found in different dominant plant groups, mainly belonging to the phyla Ascomycota and Basidiomycota, resulting in significantly higher organic matter content in the dominant plant groups compared to the CK group. The bacterial communities were dominated by the phyla Actinobacteriota, Proteobacteria, Chloroflexi, and Firmicutes. Among these microbial phyla, the Phyllanthus pinnatifida group had higher abundance, which is beneficial for vegetation colonization. Redundancy analysis showed that soil pH was significantly correlated with microbial communities. Organic matter content and pH are the main factors influencing the composition of soil microbial communities, significantly affecting the composition of microorganisms in different groups. After years of restoration, the environment of the Shengli Coalfield's spoil heap has been greatly improved. The planting of various beneficial plants has resulted in significant improvements to the soil microbial community and physicochemical properties, with Phyllanthus pinnatifida having the most positive impact. This lays the foundation for the subsequent restoration of the slope of the spoil heap.

In this study, Moderate Resolution Imaging Spectroradiometer (MODIS) derived normalized difference vegetation index (NDVI) was used to retrieve onset date of spring phenology in grasslands of Inner Mongolia (2002-2017). To validate the application of MODIS derived data, long-term retrieval and investigation on its reliability was performed. The correlation between MODIS derived green-up onset date and ground observations from 2002-2012 were given medium to high strength (R2: 0.58-0.81). Besides, relationship between seasonal climate variables, including winter and spring precipitation and temperature, and MODIS derived green-up onset date from 2002-2017 were established. Overall, linear regression analysis shows there are 8-12 days RMSE for climate variables explaining green-up onset date shifting. This satellite method might have a poor performance in sparse and snow-cover grasslands, but is fitted well in medium to dense vegetation and snow-free grasslands. These suggest MODIS estimated spring phenology has the potential to be applied in grass resources utilization in the Inner Mongolia.