The fine-scale characterization of vegetation surface information serves as a fundamental basis for studying the spatial distribution of resources and the dynamic patterns of environmental responses. Accurately extracting the distributions of different crop species is of critical importance for improving agricultural production efficiency and ensuring food security. Traditional fine-scale vegetation extraction methods often face significant challenges due to the presence of spectrally similar features and the substantial influence of background interference, which limit their applicability across large areas. As a key phenological stage of angiosperms, flowering is characterized by distinctive flowering times, floral morphology, and canopy spectral signatures, so it is an effective pathway for fine-scale vegetation extraction using remote sensing. Using rapeseed as an example, this study developed a spectral index model for precise flowering vegetation extraction (FI-R) based on Landsat OLI imagery. The model integrates a yellowness index (Blue, Green) and a peak index (Red, Nir and SWIR1) while leveraging the NDVI to mitigate background interference from spectrally similar objects. This approach successfully enables the rapid and accurate large-scale mapping of flowering vegetation under complex background conditions. The proposed method was tested in five rapeseed cultivation regions worldwide with diverse backgrounds. Validation datasets were generated using GF imagery and the U.S. CDL dataset. The FI-R model demonstrated superior capability in distinguishing flowering rapeseed from other vegetation, and achieved overall accuracies exceeding 94% in all study areas. Furthermore, FI-R is compatible with other multispectral sensors that have similar band configurations, so it is applicable to rapeseed extraction in broader contexts. The method also shows strong potential for the fine-scale extraction of other types of flowering angiosperm vegetation.

The irrigation districts of northern China face issues such as water scarcity, inability to effectively utilize flood resources, and groundwater overexploitation. In view of these challenges, this study proposes a new concept of deep storage irrigation through flood resources utilization. However, whether deep storage irrigation can recharge deep soil moisture and sustain crop production still requires further study. A two-year field experiment was conducted on summer maize in the Guanzhong Plain with five soil wetting layer depths (T1: 60 cm; T2: 90 cm; T3: 120 cm; T4: 150 cm; T5: 180 cm) and soil saturation moisture content as the irrigation upper limit. The results presented that the ranges of deep soil moisture recharge in the 100–200 cm soil profile (SMS_100–200) was 73.34–267.42 and 0–150.03 mm in 2021 (wet season) and 2022 (normal season). When the effective precipitation and irrigation exceeded 390 mm, the SMS_100–200began to linearly increase. The highest grain yield (GY) were observed at T2 and T3 treatments in 2021 (11.44 t ha⁻¹) and 2022 (11.25 t ha⁻¹), respectively. The maize GY of T4 in 2021 and T5 in 2022 were only 3.9 and 5.7% lower than the maximize GY, respectively. However, the SMS_100–200for T4 and T5 were 2.4 and 5.0 times that of T2 and T3 treatments in 2021 and 2022, respectively. Overall, the further increase in irrigation amounts induced only a slight decrease in grain yield, but it significantly increased deep soil moisture recharge. Therefore, the deep storage irrigation breaks through the traditional idea of water-saving irrigation with limited water resources, which can be utilized as an effective alternative to address the issues of water scarcity, low flood resources utilization, and groundwater level declines in the irrigation districts of northern China.

Microplastic accumulation after film mulching affects nutrients cycling in the soil–crop system. Bulk soil (BS) and rhizosphere soil (RS) have two different community compositions which lead to their different microbial nutrient acquisition abilities. Microplastics influence the rhizosphere effect. However, the mechanism by which microplastic accumulation affects the net photosynthetic rate (NPR) through rhizospheric microbial communities remains unknown. This study aimed to identify the mechanisms underlying the effects of polyethylene (PE) and polyvinyl chloride (PVC) microplastics at 0, 1, and 5% (w/w) on the NPR in the wheat–soil ecosystem using a pot experiment. Superoxide dismutase (SOD) activity was reduced by 15.35–36.7%, and that of peroxidase (POD) was increased by 32.47–61.93%, causing reductions in NPR (17.94–23.81%) in the PE5% and PVC (1 and 5%) (w/w) treatments compared with the control. The Chao1, Shannon, and Simpson indices of the bacterial and fungal diversities were lower in BS than in RS at PE1% and PVC5% (w/w), respectively. The bacterial and fungal network complexities were reduced and increased, respectively, owing to alterations in the bacterial and fungal community compositions and structures for wheat growth. The Mantel test showed that the bacterial and fungal diversity indices in BS had positive correlations with Olsen-P and phosphatase; however, those in RS were positively correlated with NO₃^–and β-1,4-glucosidase. The structural equation model indicated that wheat enzymatic and soil hydrolytic activities negatively affected NPR. Wheat has a profound antioxidant defense strategy for PE and PVC microplastic stress, which produces a synergistic effect of POD by protecting organelles and reducing tissue damage to preserve the NPR.

Organic management practices and spontaneous fermentations have become focal points in wine research due to increasing consumer interest in healthy foods and sustainable agriculture. In this study, ‘Cabernet Sauvignon’ grapes sourced from organic and conventional management vineyard (OMV/CMV) in the Ningxia region were subjected to spontaneous fermentation. The microbial, oenological, and aroma profiles of grape must and resulting wines were assessed using high-throughput sequencing (HTS), high-performance liquid chromatography (HPLC), gas chromatography with mass spectrometry (GC-MS), and sensory evaluations. Network analysis was applied to explore relationships among microorganisms, volatile compounds, and aroma attributes. Results showed that organic management significantly increased microbial species richness, α-diversity, and the variety and concentration of aroma compounds, favoring the production of natural wines with complex aroma profiles. Relative abundance of Saccharomycesin OMV reduced, promoting the prevalence of other yeast species during fermentation. Bacterial succession in wines from OMV remained stable, with Pantoeaas the dominant genus. Among oenological parameters, OMV wines significantly induced glycerol content, while reduced total acidity, tartaric acid, and citric acid content. These wines exhibited significantly higher levels of fermentative (+16%) and varietal (+72%) volatiles, as well as enhanced floral and sweet fruity aromas, along with distinct nail polish and vegetal notes. Additionally, Saccharomyces, Hanseniaspora, Metschnikowia, and Pantoeawere strongly correlated with specific volatile compounds and aroma characteristics. This study provides valuable data that can inform spontaneous fermentation practices and guide vineyard management for natural wine production.

China has limited acaricide options for tea plantations. Cyetpyrafen, a novel domestic acaricide with high efficacy, low toxicity and a negative temperature coefficient, offers an alternative for tea pest control; however, its residue fate in tea remains unclear. This study developed a method to simultaneously detect cyetpyrafen and its metabolites (M-309, M-325-1,and M-409-3) in different tea matrices to investigate their fate. Recoveries of compounds ranged from 73.4 to 106.2% with the relative standard deviations (RSDs) below 12.0%. During tea cultivation, the dissipation half-life of cyetpyrafen was 0.59d, with M-309 as a major metabolite. The residues of cyetpyrafen and M-309 were affected by different processing stages, especially water loss and high temperatures during fixing, drying and withering. The total processing factors ranged from 1.39 to 1.71 for green tea and 1.48 to 2.28 for black tea (processed from fresh tea leaves sampled at 1, 5, and 7d), respectively. The leaching rates of cyetpyrafen from green tea and black tea into tea infusions were 7.4 and 6%, respectively. The risk associated with cyetpyrafen intake from tea consumption was low, with risk quotient values below 100%. However, theoretical calculation indicated potential harm to non-target organisms from its metabolites. This research provides a reference for the safe and efficient use of cyetpyrafen in tea gardens.

The United Nations Sustainable Development Goal (SDG) 2 aims to achieve Zero Hunger by 2030. However, global hunger and food insecurity have continued to rise at an alarming rate (UN 2023). Subtropical regions are home to more than 30% of the world’s population, predominantly in developing countries where per capita farmland and food supply are only 40% of those in developed nations (FAO 2018). Meeting the Zero Hunger target amid ongoing population growth in these regions requires a substantial increase in agricultural production while minimizing soil degradation and adverse ecological impacts. This challenge is shared by many countries across South Asia, Africa, and Central and South America.
Against this background, the 4th International Symposium on Sustainable Agriculture for Subtropical Regions (ISSASR-4) was held from June 21 to 24, 2024, in Changsha, China, hosted by the Institute of Subtropical Agriculture, Chinese Academy of Sciences. The symposium brought together over 300 experts and scholars from nearly 30 countries. Under the theme “Ecosystem Management and Agricultural Green Development in Subtropical Regions”, discussions focused on four key topics: (i) regional resources and ecosystem management for enhancing agricultural productivity, (ii) green crop and animal production, (iii) minimizing adverse environmental impacts of agricultural production, and (iv) the growing role of big data, artificial intelligence(AI), and smart farming. Participants exchanged the latest research advances, identified major challenges, and explored countermeasures for agriculture and ecological sustainability in subtropical regions worldwide.
This Special Focus of the JournalofIntegrativeAgriculture(JIA) addresses these pressing issues by presenting empirical evidence and innovative solutions for agricultural green development. It comprises 13 papers covering a wide range of topics related to carbon, nitrogen, and phosphorus pathways in natural and agricultural ecosystems, with attention to microbial processes, land-use change, production management, and their effects on nutrient cycling and grain yield. We hope this collection enhances understanding of ecosystem management and green agricultural development, offering actionable insights for policymakers, researchers, and practitioners.
Section 1: Regional resources and ecosystem management
This section examines three key areas: agricultural bio-resources, soil carbon and nutrient dynamics across ecosystems, and regional grain supply–demand matching. Studies provide insights into bioinput-based agricultural frameworks, soil nutrient responses to climate change and anthropogenic influences, and the dynamic, heterogeneous patterns of grain matching. Vermelho etal.(2026) reviewed microbial bioinputs, outlining their categories, mechanisms, global challenges, and Brazil’s production infrastructure and regulatory context. Wang M M etal.(2026) reported moderate spatial variation with positive autocorrelation in soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), and total potassium (TK), noting greater vulnerability to phosphorus and potassium limitation than to nitrogen, with soil properties outweighing spatial or environmental factors in explaining nutrient variation. Another study by Wang L Y etal.(2026) identified climate and hydrological changes as key drivers of SOC loss in Dongting Lake, with accelerated loss occurring above 21.4 m elevation, suggestingthatmanaged water levels during droughts could enhance carbon sequestration. Wan etal.(2026) showed that plantations can mitigate climate change by increasing carbon storage at the aggregate scale in alpine regions. Miao etal.(2026) demonstrated a scale-dependent mismatch in grain supply and demand, highlighting how interregional flows from 1980 to 2020 reduced deficit areas. Together, these studies advance frameworks for sustainable ecosystem management.
Section 2: Green crop production in subtropical regions
Enhancing green crop production in subtropical regions requires practices that improve soil health and carbon sequestration while sustaining yields. Given the vulnerability of subtropical croplands, effective strategies for maintaining SOC are critical. Hua etal.(2026) found that long-term livestock manure substitution improves soil aggregate stability and reduces water erosion but increases lateral loss of labile organic carbon, revealing a trade-off. Kautsar etal.(2026) reported that terrace reconstruction altered rice yields between field sides and modified SOC, TN, and decomposition dynamics in the 15–30 cm layer, with subsoil fertility determining productivity. Wang J etal.(2026) demonstrated that massive granulated straw incorporation boosts SOC and crop yield in infertile soils, with accumulation efficiency ranging from 30.8 to 60.0%, primarily from plant residues. These studies highlight practical pathways for sustainable soil management.
Section 3: Environmental impacts of agricultural production
Assessing and mitigating agriculture’s environmental footprint requires a multiscale understanding of soil ecological processes. Pan etal.(2026) found that natural restoration enhances karst soil phosphorus-cycle multifunctionality more than artificial restoration or cropping, driven by increased SOC and bacterial network complexity, with rare phoD-harboring taxa playing a critical role. Wang Y etal.(2026) reported that niche outweighs genotype in shaping pea fungal communities, with β-diversity driven by species replacement and deterministic assembly in niche-based groups. Zhu etal.(2026) showed that SOC is higher in brown and yellow-brown soils and that spring irrigation significantly increases farmland SOC, supporting carbon sequestration. Zheng etal.(2026) demonstrated that spatial factors govern carbon-cycling gene abundances in uplands, while biotic and substrate factors dominate in paddy soils, revealing an integrated “microbial carbon pump” in trace-gas cycling at a continental scale. Collectively, these studies advance understanding of the mechanisms underlying soil functionality and greenhouse gas modulation.
Section 4: Big data, artificial intelligence and smart farming in agriculture
The integration of big data, AI, and smart technologies is pivotal for the digital transformation of agriculture. This section presents a study on their practical application to environmental challenges. Wang M H etal.(2026) developed an Android-based decision support system (CNPDSS) to control non-point source nitrogen (N) and phosphorus (P) pollution. Integrating GIS, a Bayesian predictive model, an optimization algorithm, and a smartphone interface, the system identified solutions that minimize both pollutant loadings and engineering costs in the Tuojia catchment, China. Its adaptive design demonstrates potential for broader application, offering a scalable tool for sustainable water quality management.
This Special Focus underscores the critical intersection of ecosystem management and agricultural development in subtropical regions. Through 13 studies organized across four themes-resource management, green production, environmental impact mitigation, and smart technology-the collection provides a science-based framework for enhancing productivity while preserving ecological integrity. It offers concrete insights for achieving sustainable food systems and advancing the UN Zero Hunger goal in some of the world’s most vulnerable and vital agricultural landscapes.

Brazil maintains a leading position in agricultural exports and stands as the world’s foremost producer and user of bioinputs in agriculture. These bioinputs generate annual savings of billions of dollars that would otherwise be allocated to chemical fertilizers and pesticides. The nation’s regulatory framework enables bioinput agriculture and serves as a model for countries transitioning toward regenerative agriculture. Brazilian legislationcategorizes bioinputs into: 1) biofertilizers (extracts); 2) biostimulants (plant growth-promoting and biocontrol agents); and 3)inoculants (active ingredient comprises one or more living microorganisms). The inoculation of soybeans with Bradyrhizobiumstrains provides approximately 90% of the nitrogen accumulated by this crop. Brazil has registered over six hundred inoculants, with at least 60% specifically designated for soybean cultivation. The annual sales of inoculants in Brazil reach approximately 120 million doses. Although beans (Phaseolusvulgaris and Vignaunguiculata) represent an essential food crop in Brazil’s staple diet and benefit from inoculation, inoculant supply remains insufficient. Regarding biocontrol,soy, corn, sugarcane, and coffee rank among the most protected crops, employing biocontrol agents against bacteria, fungi, nematodes, and insects. Bacillus, Pseudomonas, Streptomyces, Rhizobium, Azotobacter, and Paenibacillusstrains were predominantly cited in the 5,000+ bioproduct patents filed between 2022 and 2024. Among fungal genera, Trichoderma, and Penicilliumreceived the most citations. EMBRAPA's biobanks maintain over 10,000 strains of bacteria, fungi, and viruses for biocontrol, and 14,000 strains of nutrient-fixing and plant-growth promoters. Production challenges include quality control,particularly as on-farm production of inoculants becomes prevalent on larger farms, alongside product availability and supplylimitations. Brazilian farmers maintain global competitiveness partly through reduced chemical fertilizer and pesticide costs enabled by bioinput usage. As components of regenerative agriculture, bioinputs enhance soil quality, decrease carbon footprints, and support Sustainable Development Goals. Brazil's leadership in microbial bioinput utilization stems from its extensive agricultural sector, rich microbial biodiversity, and progressive regulatory framework.

Understanding the spatial distributions and corresponding variation mechanisms of key soil nutrients in fragile karst ecosystems can assist in promoting sustainable development. However, due to the implementation of ecological restoration initiatives such as land-use conversions, novel changes in the spatial characteristics of soil nutrients remain unknown. To address this gap, we explored nutrient variations and the drivers of the variation in the 0–15 cm topsoil layer using a regional-scale sampling method in a typical karst area in northwest Guangxi Zhuang Autonomous Region, Southwest China. Descriptive statistics, geostatistics, and spatial analysis were used to assess the soil nutrient variability. The results indicated that soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), and total potassium (TK) concentrations showed moderate variations, with coefficients of variance being 0.60, 0.60, 0.71, and 0.72, respectively. Moreover, they demonstrated positive spatial autocorrelations, with global Moran’s indices being 0.68, 0.77, 0.64, and 0.68, respectively. However, local Moran’s index values were low, indicating large spatial variations in soil nutrients. The best-fitting semi-variogram models for SOC, TN, TP, and TK concentrations were spherical, Gaussian, exponential, and exponential, respectively. According to the classification criteria of the Second National Soil Census in China, SOC and TN concentrations were relatively sufficient, with the proportions of rich and very rich levels being up to 90.9 and 96.0%, respectively. TP concentration was in the medium-deficient level, with the areas of medium and deficient levels accounting for 33.7 and 30.1% of the total, respectively. TK concentration was deficient, with the cumulative area of extremely deficient, very deficient, and deficient levels accounting for 87.6% of the total area. Consequently, the terrestrial ecosystems in the study area were more vulnerable to soil P and K than soil N deficiencies. Furthermore, variance partitioning analysis of the influencing factors showed that, except for the interactions, the single effect of other soil properties accounted more for soil nutrient variations than spatial and environmental variables. These results will aid in the future management of terrestrial ecosystems.