Xiaoyu Zhu

Purpose: Comparing farmland and alfalfa grassland systems under different planting scales in influencing grain yield and environmental security is crucial to achieving sustainable food development. This study aims to evaluate the environmental impacts of farmland and alfalfa grassland systems under different planting scales in the North China Plain. Methods: The environmental impacts, including energy depletion, land utilization, water consumption, global warming, acidification, and eutrophication, were evaluated using robust regression and life cycle assessment (LCA) based on the functional unit of CNY 1000 of grain (crops and alfalfa) production. Robust regression was applied to improve the accuracy of the data, and the LCA method was effectively used to compare the environmental impacts under different planting scales. Results: The comprehensive environmental impact of alfalfa production was 9% lower than that of the crop system in the North China Plain. Compared to large-scale cultivation, smallholder farming resulted in 26%, 34%, and 22% higher environmental impact indicators for alfalfa, maize, and wheat, respectively. Conclusions: The experimental results demonstrate that the robust regression model achieves high prediction accuracy and generalization ability in estimating input–output quantity. The results can provide insights into the optimization of policy initiatives oriented towards the goal of resource-conserving, cost-effective, and environmentally friendly development to facilitate regional planning and sustainable development.

Soil security assessments are an important part of the green development of agriculture and animal husbandry. To explore the research progress and development trends in the field of farmlands and grasslands soil security assessments, a bibliometric study was conducted using VOSviewer software to visually analyze 3618 papers from the Web of Science Core database on the topic of “soil security assessment” published from 1979 to 2023. The results revealed the following: (1) Research started in 1979; the number of papers can be divided based on germination, start-up, and rapid development stages. China published the most articles, the Chinese Academy of Sciences had the highest number of publications, and Science of the Total Environment issued the most publications (247). (2) Based on keywords, the research frontier can be divided into a distinct time sequence: the initial exploratory period (1979–2008), wherein relevant research focused on resource development and management; the rapid development period (2009–2015), wherein research focused on sustainable development and efficient farmland use; and the comprehensive development period (2016–2023), wherein research focused on the assessment, measurement, and evolution of cultivated land. (3) Related researches at home and abroad focus on land development and utilization, highlighting the rational development and efficient use of land; the security of industrial and supply chains, underlining risk assessment and promotion strategies; ecological security, emphasizing the ecological security assessments of agricultural production and the water environment; and ecosystem service value, underscoring spatiotemporal evolution and driving factors, evolution mechanisms, value prediction, and compensation strategy. Currently, there is an urgent need to develop soil security assessment models based on regional development, soil biology, spatial metrology, and other parameters, to establish an index system, and to analyze the evolution rules of soil security at different scales and investigate the scale effect of soil quality evaluations.

Long-term grazing leads to soil degradation in Inner Mongolia grassland. Based on the Hulunbeier meadow steppe, the variation characteristics of soil nitrogen content and storage in soil layers between 0–40 cm, under six different grazing intensities, and the response of vegetation and other physical and chemical properties of soil to grazing were studied. The main results were as follows: (1) Moderate grazing increased soil total nitrogen (TN), soluble total nitrogen (STN) and microbial biomass nitrogen (MBN) contents, while heavy grazing decreased MBN content. In the year with more rain, heavy grazing increased nitrate nitrogen (NO₃⁻-N) content and storage, while less rain increased ammonium nitrogen (NH₄⁺-N) content. (2) The proportion of 0–40 cm nitrogen components showed an upward trend in the year with more rain, and the opposite in the years with less rainfall with the increase of grazing intensity. Soil soluble organic nitrogen (SON) and NO₃⁻-N storages decreased and MBN storage increased in rainy years. (3) Soil nitrogen component contents and storages were correlated with plant growth status, soil moisture (SM) and soil bulk density (SBD), and were significantly negatively correlated with soil temperature (ST) and pH (p < 0.05). The content and storage of soil nitrogen were affected by grazing, soil, vegetation, meteorological and other environmental factors. Moderate grazing was more conducive to the improvement of soil nitrogen storage capacity and the healthy development of grassland.

Understanding the grassland ecosystem is crucial for improving grassland ecosystem functions and services such as climate regulation, water and soil conservation, carbon sequestration, and biodiversity and gene pool maintenance. However, a systematic and comprehensive review of the relevant literature is still unclear and lacking. The VOSviewer software and cluster analysis were used to visually analyze and perform dimension reduction classification on the 27,778 studies related to grassland ecosystem research based on the Web of Science database. The number of publications targeting grassland ecosystem increased rapidly from 2006 to 2021. Ecology, agronomy, and environmental science were the most popular research categories, and the top journal sources were Remote Sensing, Journal of Ecology, and Ecology and Evolution. The leading publishing countries were the United States, China, and Germany. The top three institutions were the Chinese Academy of Sciences, the University of Chinese Academy of Sciences, and Colorado State University. Cooperation between different countries and institutions had increased. Keyword co-occurrence network analysis showed that Biodiversity, Vegetation and Conservation were the most popular study areas, grassland management, climate change, land use pattern, and ecosystem impact were the hot research topics. All studies could be divided into three categories by cluster analysis: grassland ecological characteristics including basic physicochemical properties, vegetation community characteristics, aboveground and belowground biomass, and soil structural quality of grassland; driving mechanisms that demonstrated effects of human activities and climate change on grassland ecosystem function; and grassland ecosystem services that focused the influences of different grassland management strategies on ecological services, animal welfare and human well-being. The three topic categories of reviewed studies were interrelated and consistent with each other, and the performances were progressive. This paper reviewed the trend evolution through keyword hotspots and analyzed the future research directions to provide an important reference for scientists to better respond to the balance of herbage and sustainable utilization of grassland and maintenance of ecological security.