分类： 生物学 >> 生态学 提交时间： 2023-08-15 合作期刊: 《干旱区科学》
摘要： Microorganisms regulate the responses of terrestrial ecosystems to anthropogenic nutrient inputs. The escalation of anthropogenic activities has resulted in a rise in the primary terrestrial constraining elements, namely nitrogen (N) and phosphorus (P). Nevertheless, the specific mechanisms governing the influence of soil microbial community structure and ecological processes in ecologically vulnerable and delicate semi-arid loess agroecosystems remain inadequately understood. Therefore, we explored the effects of different N and P additions on soil microbial community structure and its associated ecological processes in the farmland of Chinese Loess Plateau based on a 36-a long-term experiment. Nine fertilization treatments with complete interactions of high, medium, and low N and P gradients were set up. Soil physical and chemical properties, along with the microbial community structure were measured in this study. Additionally, relevant ecological processes such as microbial biomass, respiration, N mineralization, and enzyme activity were quantified. To elucidate the relationships between these variables, we examined correlation-mediated processes using statistical techniques, including redundancy analysis (RDA) and structural equation modeling (SEM). The results showed that the addition of N alone had a detrimental effect on soil microbial biomass, mineralized N accumulation, and -1,4-glucosidase activity. Conversely, the addition of P exhibited an opposing effect, leading to positive influences on these soil parameters. The interactive addition of N and P significantly changed the microbial community structure, increasing microbial activity (microbial biomass and soil respiration), but decreasing the accumulation of mineralized N. Among them, N24P12 treatment showed the greatest increase in the soil nutrient content and respiration. N12P12 treatment increased the overall enzyme activity and total phospholipid fatty acid (PLFA) content by 70.93%. N and P nutrient contents of the soil dominate the microbial community structure and the corresponding changes in hydrolytic enzymes. Soil microbial biomass, respiration, and overall enzyme activity are driven by mineralized N. Our study provides a theoretical basis for exploring energy conversion processes of soil microbial community and environmental sustainability under long-term N and P additions in semi-arid loess areas.
分类： 地球科学 >> 地理学 提交时间： 2021-09-08 合作期刊: 《干旱区科学》
LI Cheng
WANG Qingsong
LUO Shuai
QUAN Hao
WANG Naijiang
LUO Xiaoqi
ZHANG Tibin
DING Dianyuan
DONG Qin'ge
FENG Hao
摘要： Plastic mulched ridge-furrow irrigation is a useful method to improve crop productivity and decrease salt accumulation in arid saline areas. However, inappropriate irrigation and fertilizer practices may result in ecological and environmental problems. In order to improve the resource use efficiency in these areas, we investigated the effects of different irrigation amounts (400 (I1), 300 (I2) and 200 (I3) mm) and nitrogen application rates (300 (F1) and 150 (F2) kg N/hm2) on water consumption, salt variation and resource use efficiency of spring maize (Zea mays L.) in the Hetao Irrigation District (HID) of Northwest China in 2017 and 2018. Result showed that soil water contents were 0.2%–8.9% and 13.9%–18.1% lower for I2 and I3 than for I1, respectively, but that was slightly higher for F2 than for F1. Soil salt contents were 7.8%–23.5% and 48.5%–48.9% lower for I2 than for I1 and I3, but that was 1.6%–5.5% higher for F1 than for F2. Less salt leaching at the early growth stage (from sowing to six-leaf stage) and higher salt accumulation at the peak growth stage (from six-leaf to tasseling stage and from grain-filling to maturity stage) resulted in a higher soil salt content for I3 than for I1 and I2. Grain yields for I1 and I2 were significantly higher than that for I3 and irrigation water use efficiency for I2 was 14.7%–34.0% higher than that for I1. Compared with F1, F2 increased the partial factor productivity (PFP) of nitrogen fertilizer by more than 80%. PFP was not significantly different between I1F2 and I2F2, but significantly higher than those of other treatments. Considering the goal of saving water and nitrogen resources, and ensuring food security, we recommended the combination of I2F2 to ensure the sustainable development of agriculture in the HID and other similar arid saline areas.
分类： 地球科学 >> 地理学 提交时间： 2020-06-22 合作期刊: 《干旱区科学》
摘要： The implementation of the Grain for Green Program (GGP) has changed the development track of the agricultural eco-economic system in China. In response to the results of a lag study that investigated the coupling between the GGP and the agricultural eco-economic system in a loess hilly region, we used a structural equation model to analyze the survey data from 494 households in Ansai, a district of Yan'an City in Shaanxi Province of China in 2015. The model clarified the direction and intensity of the coupling between the GGP and the agricultural eco-economic system. The coupling benefits were derived through linkages between the program and various chains in the agricultural eco-economic system. The GGP, the agroecosystem of Ansai and their potential coupling effects were in a state of general coordination. The agroecosystem directly affected the coupling effect, with the standardized path coefficient of 0.87, indicating that the agroecosystem in Ansai at this stage provided basic material support for the coupling between the GGP and the agricultural eco-economic system. The direct path coefficient of agroeconomic system impacted on the coupling effect was –0.76, indicating that partial contradictions occurred between the agroeconomic system and the coupling effect. Therefore, although the current agroecosystem in Ansai should be provided sufficient agroecological resources for the benign coupling between the program and the agricultural eco-economic system, agricultural development failed to effectively transform agroecological resources into agricultural economic advantages in this region, which resulted in a relative lag in the development of the agricultural economic system. Thus, the coupling between the GGP and the agricultural eco-economic system was poor. To improve the coupling and the sustainable development of the agricultural eco-economic system in cropland retirement areas, the industrial structure needs to be diversified, the agricultural resources (including agroecological resources, agricultural economic resources and agricultural social resources) need to be rationally allocated, and the chain structure of the agricultural eco-economic system needs to be continuously improved.
分类： 环境科学技术及资源科学技术 >> 环境科学技术基础学科 提交时间： 2019-12-06 合作期刊: 《干旱区科学》
摘要： The lack of clarity of how natural vegetation restoration influences soil organic carbon (SOC) content and SOC components in soil aggregate fractions limits the understanding of SOC sequestration and turnover in forest ecosystems. The aim of this study was to explore how natural vegetation restoration affects the SOC content and ratio of SOC components in soil macroaggregates (>250 µm), microaggregates (53–250 µm), and silt and clay (2.0 mm diameter) on SOC components were studied too. Results showed that the contents of high activated carbon (HAC), activated carbon (AC) and inert carbon (IC) in the macroaggregates, microaggregates and silt and clay fractions increased with restoration ages. Moreover, IC content in the microaggregates in topsoil (0–20 cm) rapidly increased; peaking in the 90-year-old restored forest, and was 5.74 times higher than AC content. In deep soil (20–80 cm), IC content was 3.58 times that of AC content. Biomasses of 0.5–1.0 mm diameter roots and leaf litter affected the content of aggregate fractions in topsoil, while the biomass of >2.0 mm diameter roots affected the content of aggregate fractions in deep soil. Across the soil profiles, macroaggregates had the highest capacity for HAC sequestration. The effects of restoration ages on soil aggregate fractions and SOC content were less in deep soil than in topsoil. In conclusion, natural vegetation restoration of Liaodong oak forests improved the contents of SOC, especially IC within topsoil and deep soil. The influence of IC on aggregate stability was greater than the other SOC components, and the aggregate stability was significantly affected by the biomasses of litter, 0.5–1.0 mm diameter roots in topsoil and >2.0 mm diameter roots in deep soil. Natural vegetation restoration of Liaodong oak forests promoted SOC sequestration by soil macroaggregates.
分类： 环境科学技术及资源科学技术 >> 环境科学技术基础学科 提交时间： 2019-12-06 合作期刊: 《干旱区科学》
摘要： Land evapotranspiration (ET) is an important process connecting soil, vegetation and the atmosphere, especially in regions that experience shortage in precipitation. Since 1999, the implementation of a large-scale vegetation restoration project has significantly improved the ecological environment of the Loess Plateau in China. However, the quantitative assessment of the contribution of vegetation restoration projects to long-term ET is still in its infancy. In this study, we investigated changes in land ET and associated driving factors from 1982 to 2014 in the Loess Plateau using Budyko-based partial differential methods. Overall, annual ET slightly increased by 0.28 mm/a and there were no large fluctuations after project implementation. An attribution analysis showed that precipitation was the driving factor of inter-annual variability of land ET throughout the study period; the average impacts of precipitation, potential evapotranspiration, and vegetation restoration on ET change were 61.5%, 11.5% and 26.9%, respectively. These results provide an improved understanding of the relationship between vegetation condition change and climate variation on terrestrial ET in the study area and can support future decision-making regarding water resource availability.
分类： 地球科学 >> 地球科学史 提交时间： 2018-10-29 合作期刊: 《干旱区科学》
摘要： Soil erosion on farmland is a critical environmental issue and the main source of sediment in the Yellow River, China. Thus, great efforts have been made to reduce runoff and soil loss by restoring vegetation on abandoned farmland. However, few studies have investigated runoff and soil loss from sloping farmland during crop growth season. The objective of this study was to investigate the effects of soil management on runoff and soil loss on sloping farmland during crop growth season. We tested different soybean growth stages (i.e., seedling stage (R1), initial blossoming stage (R2), full flowering stage (R3), pod bearing stage (R4), and initial filling stage (R5)) and soil management practice (one plot applied hoeing tillage (HT) before each rainfall event, whereas the other received no treatment (NH)) by applying simulated rainfall at an intensity of 80 mm/h. Results showed that runoff and soil loss both decreased and infiltration amount increased in successive soybean growth stages under both treatments. Compared with NH plot, there was less runoff and higher infiltration amount from HT plot. However, soil loss from HT plot was larger than that from NH plot in R1–R3, but lower in R4 and R5. In the early growth stages, hoeing tillage was effective for reducing runoff and enhancing rainfall infiltration. By contrast, hoeing tillage enhanced soil and water conservation during the late growth stages. The total soil loss from HT plot (509.0 g/m2) was 11.1% higher than that from NH plot (457.9 g/m2) in R1–R5. However, the infiltration amount from HT plot (313.9 mm) was 18.4% higher than that from NH plot (265.0 mm) and the total runoff volume from HT plot was 49.7% less than that from NH plot. These results indicated that crop vegetation can also act as a type of vegetation cover and play an important role on sloping farmland. Thus, adopting rational soil management in crop planting on sloping farmland can effectively reduce runoff and soil loss, as well as maximize rainwater infiltration during crop growth period.
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