安徽省旱涝灾害及其对农作物产量影响

通过对建国以来安徽省多种农业气象资料分析，采用Z指数方法建立安徽省旱涝灾害气候判别指标，分析安徽省旱涝灾害发生规律。结果表明:1961—2000年安徽省有13年偏涝、13年偏旱；分区域看，淮北旱多于涝，沿淮、江淮、江南旱涝相当，沿江、大别山区涝多于旱。通过水稻（一季稻）、小麦典型旱涝年灾损率与发育期间气象条件、旱涝程度的对比统计分析，建立了分区水稻、小麦旱涝灾害损失评估模型和指标。春季涝渍灾害是影响安徽省冬小麦产量的主要灾害，其对冬小麦产量的危害程度远大于干旱，尤以4—5月发生的涝渍影响最严重，极重涝渍灾害的减产损失可达4成以上。同时重点研究了春季渍害对冬小麦产量的影响，提出改进的涝渍强度指标Qw，并进一步综合分析作物的敏感性和区域脆弱性对灾损率的影响。对1961—2000年冬小麦灾损率进行的敏感性和脆弱性订正表明，订正后拟合误差平均值和差异变率都明显降低，灾损评估精度得到提高。     

The economic impact of climate change on Kenyan crop agriculture: A Ricardian approach

This paper measures the economic impact of climate on crops in Kenya. We use cross-sectional data on climate, hydrological, soil and household level data for a sample of 816 households. We estimate a seasonal Ricardian model to assess the impact of climate on net crop revenue per acre. The results show that climate affects crop productivity. There is a non-linear relationship between temperature and revenue on one hand and between precipitation and revenue on the other. Estimated marginal impacts suggest that global warming is harmful for crop productivity. Predictions from global circulation models confirm that global warming will have a substantial impact on net crop revenue in Kenya. The results also show that the temperature component of global warming is much more important than precipitation. Findings call for monitoring of climate change and dissemination of information to farmers to encourage adaptations to climate change. Improved management and conservation of available water resources, water harvesting and recycling of wastewater could generate water for irrigation purposes especially in the arid and semi-arid areas.     

Estimation of seasonal crop water consumption in a vineyard using Bowen ratio‐energy balance method

Information about seasonal crop water consumption is useful to develop the appropriate irrigation scheme. Measurements of energy balance components using the Bowen ratio method were made for a complete growing season at a vineyard in the arid region of northwest China. Vine in the experiment was furrow‐irrigated using a trellis system. The measured evapotranspiration was compared with estimates using the soil water balance method. It is shown that the Bowen ratio method provided accurate estimates of evapotranspiration from the vineyard and this requires that the Bowen ratio system is appropriately installed. The energy balance components showed typical diurnal pattern with peaks that occurred around the midday, except for the ground heat flux which delayed its peak by 2–3 h. The sensible heat flux was greater than the latent heat flux and followed the net radiation closely. The ratio of the latent heat flux to net radiation was low in the early growing season and increased over time. Under the limited irrigation experienced in the vineyard, the latent heat flux was controlled by available soil moisture and the total evapotranspiration in the growing season was 253 mm. The seasonal progression of the crop coefficient is similar to that reported in the literature, with the maximum occurring during the month of September. The crop coefficient can be estimated as a non‐linear function of day of year (DOY) and used to estimate evapotranspiration from vineyards in the region. Copyright © 2007 John Wiley & Sons, Ltd.     

农作物长势遥感监测业务化应用与研究进展

农作物长势监测可为田间管理提供及时的决策支持信息和早期估产提供依据。为了更好地研究作物生长过程中不同遥感监测作物长势方法的适用性,从多光谱遥感数据、高光谱遥感数据和微波遥感数据的应用及遥感监测指标与模型模拟方面综述了国内外农作物长势遥感监测研究及业务化应用的最新进展,指出了未来拟重点加强的研究任务,包括高时空分辨率和高光谱分辨率遥感数据的业务化技术、多遥感反演参数协同监测作物长势技术研发、基于遥感信息与作物过程模型的集合预报技术研究、全球尺度作物长势监测业务运行系统研发。     

冬小麦农田裸温与气温差异分析及其应用

以矮秆代表作物冬小麦为研究对象,利用郑州农业气象试验站2010年10月15日—2011年6月2日农田小气候观测的各层裸温、气温、总辐射和覆盖度资料,采用对比差值、温度垂直梯度等方法统计分析,并对温度对比差值和总辐射曝辐量相关关系和温度的垂直梯度分布特征进行了研究,结果表明:25cm、150cm和300cm高度的日平均裸温和气温变化趋势基本一致,其对比差值呈由小变大趋势;各层裸温和气温的日分布符合温度日变化分布的一般规律,垂直梯度变化比较明显;各层对比差值呈单峰分布,峰值出现在正午12时左右;裸温和气温的对比差值与总辐射曝辐量呈线性相关。裸温与气温的垂直梯度变化有很好的一致性,可利用裸温不同层次间垂直梯度变化特征确定气温传感器合理的安装高度;根据麦田裸温垂直梯度变化特征,考虑到温度防辐射罩高度限制,矮秆作物田间小气候气温应在距离地表面25cm、50cm和150cm高度附近分别设置观测层次。     

Potential impact of future climate change on crop yield in northeastern China

We evaluated the potential impact of future climate change on spring maize and single-crop rice in northeastern China(NEC) by employing climate and crop models. Based on historical data, diurnal temperature change exhibited a distinct negative relationship with maize yield, whereas minimum temperature correlated positively to rice yield. Corresponding to the evaluated climate change derived from coupled climate models included in the Coupled Model Intercomparison Project Phase 5(CMIP5) under the Representative Concentration Pathway 4.5 scenario(RCP4.5), the projected maize yield changes for three future periods [2010–39(period 1), 2040–69(period 2), and 2070–99(period 3)] relative to the mean yield in the baseline period(1976–2005) were 2.92%, 3.11% and 2.63%, respectively. By contrast, the evaluated rice yields showed slightly larger increases of 7.19%, 12.39%, and 14.83%, respectively. The uncertainties in the crop response are discussed by considering the uncertainties obtained from both the climate and the crop models. The range of impact of the uncertainty became markedly wider when integrating these two sources of uncertainty. The probabilistic assessments of the evaluated change showed maize yield to be relatively stable from period 1 to period 3, while the rice yield showed an increasing trend over time. The results presented in this paper suggest a tendency of the yields of maize and rice in NEC to increase(but with great uncertainty) against the background of global warming, which may offer some valuable guidance to government policymakers.     

Angstrom公式参数对ET0的影响及FAO建议值适用性评价

作为计算太阳总辐射(R_s)的主要公式,Angstrom公式参数(a、b)的合理取值是计算参照腾发量(ET₀)的重要前提。针对FAO所提出的a、b建议值(a=0.25、b=0.5)在中国无辐射观测资料地区被大量使用,而其合理性尚未得到系统评价的情况,基于中国104个地面站的观测数据,在逐月时间尺度上,讨论了a、b变化对ET₀的影响,分析了a、b的地区分布规律,评价了FAO建议值所导致的ET₀计算误差,进而阐明了该建议值在中国7个区域的适用性。提出了无辐射资料情况下a、b的地区综合取值方法。主要研究结论是:①参数a、b偏差对ET₀的计算有重要影响,在中国无资料地区采用FAO建议值将导致较大的太阳总辐射(R_s)和ET₀计算误差。②大多数站点,a的率定值较FAO建议值明显偏小,而b的率定值明显偏大。新疆地区和华南地区a、b率定值分布比较集中,而在其它区域比较分散。③FAO建议参数值在东北、西北和新疆3个区域计算ET₀的适用性较好,而在西南和华南两个区域的适用性很差,计算的ET₀偏高较大。④提出的地区综合取值方法,能使R_s和ET₀的计算精度较FAO建议值显著提高。     

Improving the simulation of fine-resolution landscape changes by coupling top-down and bottom-up land use and cover changes rules

Modelling land use and cover changes (LUCC) at local and landscape scales simultaneously, in terms of composition and configuration, remains today highly challenging. Agricultural landscapes offer an illustrative context for this purpose. This article presents a modelling platform (DYPAL) able to simulate LUCC at both local (agricultural parcel, farm) and landscape levels by combining LUCC processes with an optimization algorithm. The efficiency of this approach is assessed by comparing it with an approach applying the same LUCC processes without optimization. Simulations have been developed for two representative case studies of temperate intensive agricultural mosaics: (1) neutral landscapes with simple and theoretical rules and (2) observed landscapes with realistic crop successions rules. Results show that this modelling platform improves the simulation of LUCC achieved at fine resolution, although not systematically. Improvements are observed when compared to theoretical farming practices. But, when compared with an observed landscape, it is true for one type of (arable) farms only. Several hypotheses are discussed, such as the fact that farmers possibly do not follow optimized rules. Finally, this study illustrates that the use of several indices is crucial to assess whether a simulated landscape is realistic or not, because it does not rely to the assessment of the predictive power of the model.     

遥感信息与作物模型结合在冬小麦区域模拟中的应用

遥感数据与作物模型结合是当前农业信息技术应用研究的重要内容和发展趋势之一,能够解决单独利用遥感或作物模型无法解决的问题。为了开展大范围、区域性作物生长过程的模拟和产量预测,首先对作物模型WOFOST进行了订正和验证,使得调整后的模型适于模拟河南新乡县冬小麦生长;根据实际生产分三类情形模拟新乡县2002—2003年度冬小麦的生长发育状况;利用全生育期内能获取的Landsat-7 ETM+数据反演叶面积指数,结合WOFOST模型的模拟情况,确定每个像元对应的冬小麦的生长状况,从而在像元上实现了WOFOST模型对冬小麦生长的模拟;最后对照比较本研究方法的结果与当年新乡县冬小麦的统计情况,结果相近,验证了本文研究方法的技术可行性。     

Evaluating the effect of non-uniform and deficient irrigation—Part I

A method for evaluating the effect of non-uniform and deficient irrigation is presented. The method is based on a deterministic mathematical model that evaluates the effect of the soil water fluctuation in the root zone during the irrigation season on the crop yield.The problem is viewed in conjunction with the management strategy of irrigation water application under the assumption that only shortage of water causes a reduction in yield. The parameters describing the deficit zone of the application pattern, the soil-crop-atmosphere system and the crop response are incorporated in the model. Crop yield predictions are made through the relative water use and a multiplicative and an additive yield functions.A numerical example is used to illustrate the use of the model in sprinkler irrigation practice. The results agree well with those derived from the mathematical model evaluating the irrigation regime and the yield on each square of the irrigated area separately.