甘肃陇中黄土高原农业灌溉耗水系数监测试验研究

选择甘肃省临洮县洮惠渠灌区为试验研究区,通过直接观读、自动监测等技术手段,获取试验灌区的引水量、退水量、土壤墒情、降水量及蒸发量等水文基础数据。以水文监测基础数据为依据,采用引排差法、水分平衡法等相结合的方法,开展了农业灌溉耗水系数试验研究。初步试验结果表明:试验灌区灌溉期平均耗水系数为0. 730,典型地块灌溉期平均耗水系数为0. 671,2016年试验灌区降水量较常年偏少13. 0%~26. 3%,总体上属轻度干旱年份。该研究成果可为甘肃陇中黄土高原区水资源管理提供技术支撑。     

Background concentrations of elements in surface soils and their changes as affected by agriculture use in the desert-oasis ecotone in the middle of Heihe River Basin,North-west China

The concentrations of twenty four chemical elements in the surface layer of natural desert soils and the cultivated farmland soils were measured at a desert-oasis ecotone in the middle of Heihe river basin, north-west China. Background values were estimated for (a) major elements (Si 335.3 g kg^− 1, Al 49.4 g kg^− 1, Fe 19.1 g kg^− 1, Ca 29.4 g kg^− 1, Mg 8.9 g kg^− 1, K 20.1 g kg^− 1, Na 17.5 g kg^− 1 and P 0.338 g kg^− 1), (b) heavy metals and non-metals (Cr 55.8 mg kg^− 1, Mn 404.8 mg kg^− 1, Ni 17.7 mg kg^− 1, Cu 5.1 mg kg^− 1, Zn 33.7 mg kg^− 1, Pb 15.5 mg kg^− 1 and As 5.2 mg kg^− 1) and (c) other trace elements (Ti 2.0 mg kg^− 1, V 55.3 mg kg^− 1, Co 5.7 mg kg^− 1, Rb 82.4 mg kg^− 1, Sr 232.9 mg kg^− 1, Y 14.7 mg kg^− 1, Zr 194.9 mg kg^− 1, Nb 7.8 mg kg^− 1 and Ba 720.6 mg kg^− 1). After natural desert soil was cultivated for agricultural use, significant changes in element concentrations occurred under tillage, irrigation and fertilisation management. Compared to natural soil, the for the levels of Si, K, Na, Sr, Zr and Ba decreased, and no changes were observed for Rb, while the values of the other 17 elements increase in agricultural soil from 1.2 to 3.5 times. However, their absolute concentrations are still low, suggesting that the arable soil in this region remains comparatively a clean soil. The increased silt, clay and organic carbon content, under long-term irrigation, enriched the fine-grained materials, and application of fertilisers and manure contributed to the accumulation of most elements in arable soil. The accumulation of elements in agricultural soil increased with increasing cultivation years and extent of soil development.     

Spatio-temporal Distribution of Three Kinds of Flash Droughts over Agricultural Land in China from 1983 to 2015

At present, flash drought occurs globally and regionally and causes a lot of socio-economic loss in a very short time. Therefore, flash drought has been regarded as one of the hottest issues in drought research. However, flash drought monitoring, prediction and decision-making have encountered a lot of challenges due to its multiple driven factors and complex spatio-temporal process. Aiming at this problem, this paper focused on the agricultural land in China, and analyzed the spatio-temporal distribution of three kinds of flash droughts (i.e., precipitation-deficit, high-temperature, and composite flash droughts) from 1983 to 2015. We studied the occurrences, duration, spatial distribution, temporal distribution, and trend of all three kinds of flash droughts. Our results demonstrated that, the occurrences of flash drought agricultural land in China increased year by year, among which high-temperature flash drought increased dramatically; duration of flash droughts had different trends, but the variations were relatively smooth; Northeast China was identified as a vulnerable area of flash drought, indicating more flash drought events and longer duration; flash droughts in China were found to concentrate in spring (high-temperature drought) and summer seasons (precipitation-deficit drought). This study is helpful for building new flash drought monitoring method and system, and it is also valuable for flash drought preparedness on regional scale.     

中国农业地理和土地利用的近期研究

近十余年来,中国农业地理与土地利用的研究主要在以下方面:农业地理丛书的编写,完成了中国农业地理总论和21部分省(自治区、直辖市)的农业区域地理著作;承担全国综合农业区划、自然区划、农业各部门与农业技术条件区划,进行了农业区划理论与方法的研究;对农业发展战略与我国人口、资源与环境的国情研究;为促进农业生产稳定发展,以因地制宜为原则进行农业各部门生产布局研究;1/100万土地利用图与土地资源开发、利用和保护的研究。上述研究是持续而广泛的,在理论上和实践上都取得了很大进展。     

空间信息技术在农业保险中的应用研究

中国是农业灾害发生频繁且灾情严重的国家之一。农业保险已成为农民灾后恢复生产和灾区重建的重要资金来源,风险保障和经济补偿作用日益凸显。但是,农业保险面临着信息不对称和经营成本高等问题。而利用3S等空间信息技术,可将保险标的空间化,建立承保标的空间数据库,为承保和理赔工作提供空间数据和分析管理支持,实现＂按图承保＂和＂按图理赔＂,以空间信息技术支持的农业保险创新应用促进了农业保险模式的转变,从而有效地解决农业保险存在的信息不对称和经营成本高等问题,充分发挥农业保险支农惠农的社会管理职能,提升农业保险的风险管理水平,以更好地服务＂三农＂。     

Catchment area‐based evaluation of the AMC‐dependent SCS‐CN‐based rainfall–runoff models

Using a large set of rainfall–runoff data from 234 watersheds in the USA, a catchment area‐based evaluation of the modified version of the Mishra and Singh (2002a) model was performed. The model is based on the Soil Conservation Service Curve Number (SCS‐CN) methodology and incorporates the antecedent moisture in computation of direct surface runoff. Comparison with the existing SCS‐CN method showed that the modified version performed better than did the existing one on the data of all seven area‐based groups of watersheds ranging from 0·01 to 310·3 km². Copyright © 2005 John Wiley & Sons, Ltd.     

Agricultural water poverty: Using Q-methodology to understand stakeholders' perceptions

The aim of this Q methodology study was to identify perceptions of farmers and agricultural specialists toward agricultural water poverty concept and its causes in Marvdasht County, Iran. Seventy five participants completed the Q sort procedure. Data analysis identified seven types of perceptions toward agricultural water poverty: Management-adherents, Adaptive-adherents, Fatalists, Support-seekers, Farmer blamer Pessimists, Technocratic Realists and Optimists. The first four types of perceptions were dominated by farmers and the last three by agricultural specialists. These different perspectives indicated that various individuals think differently about the nature, causes, effects and permanency of agricultural water poverty. Understanding the multiple meaning systems of agricultural water poverty for decision and policy makers will be critical as they may provide the basis for the development of more appropriate strategies to mitigate water poverty in agricultural sector.     

The Role of Local Knowledge in the Risk Management of Extreme Climates in Local Communities: A Case Study in a Nomadic NIAHS Site

In the context of climate change, research on extreme climates and disaster risk management has become a crucial component of climate change adaptation. Local communities, which have been facing extreme climates for a long time in their production and daily life, have developed some locally applicable traditional knowledge that has played an important role in their adaptation to extreme climate and disaster risk management. Therefore, this research aims to link Local knowledge (LK) to community extreme climate disaster risk management in order to construct a conceptual model. It then takes the extreme climate adaptation strategy of traditional nomads in a temperate grassland of China as an example to analyze the role of LK in extreme climate adaptation using the proposed theoretical framework. The main research objectives of this study are: (1) To construct a conceptual model to illustrate the relations among extreme climate events, risk management, LK, and farmers' adaptation strategies; (2) To apply the theoretical framework to a field case to reveal context-specific extreme climate adaptation mechanisms with LK as a critical component; (3) To test the framework and provide suggestions for the extreme climates adaptation, and the conservation of LK related to climate change adaptation. The results show that from the perspective of disaster risk management, local communities could manage extreme climates as a disaster risk through adaptation strategies formed from LK, because as a knowledge system, LK contains relevant knowledge covering the whole process of disaster risk management.     

Modeling N2O Emissions from Agricultural Fields in Southeast China

DNDC, a rainfall-driven and process-oriented model of soil carbon and nitrogen biogeochemistry, is applied to simulate the nitrous oxide emissions from agricultural ecosystem in Southeast China. We simulated the soil N₂O emission during a whole rice-wheat rotation cycle (from Nov. 1, 1996 to Oct. 31, 1997) under three different conditions, which are A) no fertilizer, B) both chemical fertilizer and manure and, C) chemical fertilizer only. The processes of N₂O emission were discussed in detail by comparing the model outputs with the results from field measurement. The comparison shows that the model is good at simulating most of the N₂O emission pulses and trends. Although the simulated N₂O emission fluxes are generally less than the measured ones, the model outputs during the dryland period, especially during the wheat reviving and maturing stages in spring, are much better than those during the paddy field period. Some sensitive experiments were made by simulating the N₂O emissions in spring, when there is a smallest gap between the simulated fluxes and the measured ones. Meanwhile, the effects of some important regulating factors, such as the rainfall, N deposition by rainfall, temperature, tillage, nitrogen fertilizer and manure application on N₂O emission during this period were analyzed. From the analysis, we draw a conclusion that soil moisture and fertilization are the most important regulating factors while the N₂O emission is sensitive to some other factors, such as temperature, manure, tillage and the wet deposition of atmospheric nitrate.     

The Effect of Farmland Fragmentation on the Intensity of Farmland in Different Utilization Ways

The agricultural development of mountainous areas in China is undergoing the transformation from the traditional agricultural land use mode dominated by single and inefficient grain production to the new agricultural land use mode such as high-yield and efficient horticultural crops. The research on the impact of farmland fragmentation on the agricultural land intensity degree is the basis of agricultural modernization and land remediation in mountainous areas. Based on the UAV high-resolution remote sensing image data of two typical villages in Guizhou Province and the questionnaire survey data of farmers, using the road accessibility index of farmers' plot, the area index and the shape index to measure the degree of farmland fragmentation, we analyzed the impact of different degrees of farmland fragmentation on the traditional and new types of farmland use intensification. The research showed that the farmland fragmentation had a significant negative impact on the intensive degree of agricultural land, but the impact on the intensive degree of agricultural land in different ways of use was different. With the intensification of the degree of farmland fragmentation, the impact on the input and output of horticultural crops and other new-type agricultural land utilization was less than that of grain crops and other traditional agricultural land utilization. Adjusting agricultural structure and transformation of farmland utilization greatly alleviated the negative impact of farmland fragmentation on farmland intensity in mountainous areas.