The rapid growth of the global population and the transformation and upgrading of dietary structures have led to a widening gap in the demand for cropland resources. Research on agricultural land reallocation that seeks to maximize cropland availability and increase grain production while also considering the preservation of natural ecosystems still has gaps. Following the theoretical assumptions of the agricultural land reallocation process, this study constructs a comprehensive framework for integrating scale, structure, and prioritization. Sichuan Province, China's main grain-producing region, is used as an example for a case study. The results demonstrate that the scale of agricultural land reallocation decreased from 56,742.01 to 44,965.52 km2 after correcting the evaluation of ecological conservation importance and crop production suitability under spatial and non-spatial constraints. There are significant differences in crop production suitability for agricultural land reallocation structures. Despite the wide spatial distribution of forest land, its utilization is challenging. Therefore, cropland, garden land, and grassland are prioritized for exploitation and utilization. In the eight priority zones for agricultural land reallocation, the main obstacles are constituted by single or composite factors of utilization convenience, spatial agglomeration, and facility stability. In general, agricultural land reallocation needs to be supported by considering different dimensions of resource availability, structural convertibility, and spatial compatibility. This approach maximizes the availability of resources for grain production while minimizing damage to natural ecosystems.

A sustainable use of croplands should utilize beneficial services provided by their resident soil microbiome. To identify potentially adverse environmental effects on soil microbiomes in the future, a better understanding of their natural variability is fundamental. Here, we characterized the abundance and diversity of soil microbial communities over 2 years at two-week intervals on three neighboring fields at an operational farm in Northern Germany. Field soils differed in texture (clay, loam) and tillage (soil conservation vs. conventional). PCRamplicon analyses of soil DNA revealed distinct temporal variations of bacteria, archaea, fungi, and protists (Cercozoa and Endomyxa). Annual differences and seasonal effects on all microbial groups were detected. In addition to soil pH, prokaryotic communities varied with total soil C and N, but fungi with temperature and precipitation. The C/N ratio had contrasting effects on prokaryotic phyla and protistan classes, but all fungal phyla responded positively. Irrespective of the sampling date, prokaryotic and fungal but not protistan community compositions from the three soils were distinct. Compositional turnover rates were higher for fungi and protists than for prokaryotes and, for all, lower in clay. Conventional tillage had the strongest effect on protist diversity. In co-occurrence networks, most nodes were provided by prokaryotes, but highly connected nodes by predatory protists in the first, and by saprotrophic fungi in the second year. The temporal variation established here can provide insights of what is natural and thus below the limits of concern in detecting adverse effects on the soil microbiome.

Atmospheric ammonia (NH3) has multiple impacts on the environment, climate change, and human health. China is the largest emitter of NH3 globally, with the dynamic inventory of NH3 emissions remaining uncertain. Here, we use the second national agricultural pollution source censuses, integrated satellite data, 15N isotope source apportionment, and multiple models to better understand those key features of NH3 emissions and its environmental impacts in China. Our results show that the total NH3 emissions were estimated to be 11.2 +/- 1.1 million tonnes in 2020, with three emission peaks in April, June, and October, primarily driven by agricultural sources, which contributed 74% of the total emissions. Furthermore, employing a series of quantitative analyses, we estimated the contribution of NH3 emissions to ecosystem impacts. The NH3 emissions have contributed approximately 22% to secondary PM2.5 formation and a 16.6% increase in nitrogen loading of surface waters, while ammonium deposition led to a decrease in soil pH by 0.0032 units and an increase in the terrestrial carbon sink by 44.6 million tonnes in 2020. Reducing agricultural NH3 emissions in China would contribute to the mitigation of air and water pollution challenges, saving damage costs estimated at around 22 billion US dollars due to avoided human and ecosystem health impacts.

The rapid expansion of cropland in Cambodia, the world's seventh-largest rice exporter, has created an imbalance in land use structure. However, there is a lack of quantitative investigation of the loss of ecological land as a result of the expansion of cropland and its drivers. In this research, spatial autocorrelation, landscape pattern index and transfer matrix methods were used based on land use data from 2000 to 2023. Then, the eXtreme Gradient Boosting-SHapley Additive exPlanations (XGBoost-SHAP) and Geographic Detector were used to explore the drivers of cropland expansion. The findings indicate that the expanse of agricultural land in Cambodia has significantly increased by 13.47%. The proportion of cropland to the land area (37.87%) is close to that of forest (40.19%). Cultivated land is dominated by rice fields, supplemented by drylands. Spatial clustering is obvious in both drylands and rice fields. Drylands are mainly concentrated in the eastern and western mountainous areas and the northern border, while rice fields are concentrated in the central plains. Cultivated land encroached on a total of 30,579.27km2 of ecological land, of which 62.88% was dry land and 37.12% was rice fields. Forests and shrubs are the main source of expansion of cropland. In addition, soil type (0.18), elevation (0.17) and GDP (0.17), population (0.52) and their interactions strongly drove the expansion of dryland and rice fields. Cambodia should conduct scientific research to assess the demand for cropland by population growth and economic progress. It should realize the orderly growth of cultivated land, reduce the damage to ecological land, and promote the coordinated development of society, environment and economy.

Food security, a crucial issue for the development of humankind, is often severely constrained by water scarcity. As a globally recognized most advanced agricultural water-saving technology, drip irrigation under plastic mulch (DIPM) has played a significant role in grain production. However, a comprehensive review of the dual impacts of this practice in farmland remains lacking. This study has conducted an exhaustive review of DIPM research from 1999 to 2023 and employed CiteSpace software to perform a co-occurrence and clustering analysis of keywords in order to reveal research hotspots and trends. The results show that the attention to DIPM technology has increased annually and reached a peak in 2022. China leads in the number of publications in this field, reflecting its emphasis on agricultural water-saving technologies. This study critically discusses the dual impacts of DIPM on farmland. On the positive side, DIPM can improve soil temperature and moisture, enhance nutrient availability, promote water and nutrient absorption by roots, and increase the crop growth rate and yield while reducing evaporation and nitrogen loss, suppressing weed growth, decreasing herbicide usage, and lowering total greenhouse gas emissions. On the negative side, it will cause pollution from plastic mulch residues, damage the soil structure, have impacts on crop growth, and lead to increased clogging of drip irrigation systems, which will increase agricultural costs and energy consumption, hinder crop growth, hamper soil salinization management, and further reduce the groundwater level. The future development of DIPM technology requires optimization and advancement. Such strategies as mechanized residual-mulch recovery, biodegradable mulch substitution, aerated drip irrigation technology, and alternate irrigation are proposed to address existing issues in farmland triggered by DIPM. This review advocates for the active exploration of farming management practices superior to DIPM for future agricultural development. These practices could lead to higher yields, water-nitrogen efficiency, and lower environmental impact in agricultural development.

Heavy metal composite pollution, such as Cd-Pb, occurs commonly in agriculture soils around the world, potentially harming the ecological environment and human health via food chain/network migration. There are numerous strategies for treating and rehabilitating polluted farmland today, including the use of attractive plants for phytoremediation. However, it is unclear how to use attractive plants to properly treat and fully utilize Cd-Pb composite damaged farms. The combined Cd-Pb pollution of agriculture in Xieping village, Huixian county, Gansu province is increasingly prevalent. Therefore, based on the results of literature research and the actual situation of the study area, nine kinds of ornamental plants with Cd-Pb composite pollution remediation potential and comprehensive utilization value were first selected in this paper, and the greenhouse test was carried out in the Cd-Pb composite pollution farmland in the study area. Second, the bioconcentration factor (BCF), transfer coefficient (TF), and economic feasibility principle were utilized to select the best treatment plants, and a novel model of effective remediation and comprehensive exploitation of Cd-Pb composite damaged farmland was developed. The results showed that the nine tested plants grew well under the Cd-Pb combined pollution stress, and all of them showed certain tolerance. However, the biomass, Cd-Pb accumulation, enrichment and transport capacity of the different plants were significantly different. Among them, Paeonia suffruticosa Andr., Rumex acetosa L., Calendula officinalis L., Rose chinensis Jacq., Tagetes erecta L. and Impatiens balsamina L. show excellent restorative abilities. Combining the ornamental value, safety and economy of flowering plants, P. suffruticosa, R. chinensis, C. officinalis, T. erecta and I. balsamina were finally selected as the plants for the effective remediation and comprehensive utilisation of Cd-Pb composite pollution in farmland. In conclusion, this study proposes a new model for the effective remediation and comprehensive utilisation of heavy metal composite pollution in farmland by flowering plants with economic feasibility.\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$.$$\end{document}

The Loess Plateau plays a significant role in the implementation of China's Grain for Green Project due to severe ecological damage in the region. In order to monitor and evaluate the effects of Grain for Green Project, a study was conducted in Wuqi County, which is representative of the Loess Plateau. The study utilized remote sensing (RS) and geographic information system (GIS) technologies to analyze the spatial and temporal patterns of Grain for Green Project and assess its effects. The findings indicate that the Grain for Green Project resulted in notable improvements in Wuqi County from 2000 to 2018. Firstly, there was a significant increase in vegetation coverage, accompanied by a reduction in soil erosion intensity. Secondly, approximately 64 % of cropland was converted, leading to an expansion of forest and grassland areas. Thirdly, the focus of vegetation restoration was primarily on converting cropland to grassland, indicating its suitability for the county compared to forestation. Lastly, the conversion of steep cropland (>25(degrees)) was influenced by the density of less steep cropland (<25(degrees)). This study emphasizes the importance of guiding farmers in selecting appropriate vegetation restoration strategies and finding a balance between erosion control and agricultural production within the Grain for Green Project. Furthermore, the study recognizes that the project's significant effects are not solely attributed to land use conversion but also to the self-restoration of vegetation. This shift towards a self-restoration perspective is crucial for the future high-quality development of the Grain for Green Project.

Climate warming has significantly changed the near-surface soil freeze state, significantly impacting terrestrial ecosystems and regional agroforestry production. As Northeast China (NEC) is highly sensitive to climate change, this study introduces the concept of velocity to analyze the spatial pattern of frozen days (F-DAY), onset date of soil freeze (F-ON), offset date of soil freeze (F-OFF), and number of soil freeze/thaw cycles in spring (F-TC) in NEC from 1979 to 2020. We observed that the velocity changes of F-DAY, F-ON, and F-TC in croplands were significantly higher than those in forests (difference > 1 km yr(-1)), with the fastest velocity changes found in the cropland of the Songnen Plain. The highest velocity of FOFF was found in the forests of the Greater Khingan Range. In most study areas (> 60%), the isoline of F-DAY/F-ON/F-OFF/F-TC showed a northward movement. The isoline of F-DAY/F-ON/F-OFF/ F-TC moved in the cold direction in each cropland region (Sanjiang, Songnen, and Liaohe River Plains) and forest regions (Greater Khingan and Lesser Khingan Ranges, and the Changbai Mountains). The results of the quantitative analysis indicate that air temperature (T-A) had a more significant effect on the velocity change of F-DAY and F-ON in cropland, whereas snowpack is the dominant factor in forests. In both forests and croplands, the main factor affecting the velocity of F-OFF was snowpack, and T(A )mainly affected the F-TC. This study is significant for formulating regional climate change countermeasures and maintaining ecological security in cold regions.