黑河流域中游制种玉米农田土壤水分运移规律

基于2009年中国科学院临泽内陆河流域研究站绿洲农田小气候、土壤蒸发和土壤水分动态监测等多源观测试验数据,运用Hydrus-1D模型模拟大田制种玉米生长条件下,土壤水分运移过程和各水分通量,并对当前灌溉制度下农田水分利用率进行评估.结合相关监测数据对模拟结果进行评价,整个模拟期作物蒸腾量、土壤蒸发量、土壤蓄水变化量和渗漏量分别为316.4、100.3、45.5 mm和339.5 mm.玉米在初生阶段、发育阶段、中期阶段、后期阶段的蒸腾水量占灌溉水分的3.6％、10.6％、46.7％和49.6％,占蒸散量的7.2％、28％、82.7％和81.4％.农田系统各水分通量的变化规律及相对比例明显受作物生长和灌水事件影响,当前灌溉制度下农田水分利用率较低,在初生阶段减少土壤蒸发和中后期阶段增加灌溉频率、减少灌溉定额是提高干旱区灌溉水分利用效率的有效手段.     

宁夏南部山地易旱区农田水分生产潜力开发初探

本文探讨了农田水分的动态变化规律及其对作物生长发育的影响，分析了农田水分利用效率及潜力。通过试验，研究了水分利用效率与地力的关系，认为地力不足是影响农田水分利用效率的重要原因，并相应地提出了开发农田水分生产潜力的途径。     

作物冠层对喷灌水分分布影响的研究进展

喷灌水分到达冠层以后,经过冠层的截留和水分再分配过程,主要以两种方式到达地面,即穿过冠层直接落入土壤和通过叶片的集水,然后以茎秆为通道流入土壤.以不同方式进入土壤中的水量与作物的种类、冠层结构、种植密度,以及喷灌系统和喷灌时的农田小气候等因素有关.本文根据喷灌水分在农田的分布特点,把喷灌系统和作物结合起来,提出了喷灌有效灌水均匀系数的概念.该系数能综合反映灌溉水经过冠层再分配过程以后,田间水分的有效性.     

旱作农田水肥耦合研究进展

在查阅1970～2004年国内外大量旱作农田水肥耦合研究资料的基础上,重点对其中30篇进行了分析总结。综合评述了旱作农田水肥效应关系、水肥对作物生长和产量的影响、不同水肥条件对作物水分利用效率(WUE)的影响、施肥对农田生态环境的影响以及水肥耦合模型和研究方法等研究进展情况。指出今后水肥耦合研究应该加强施肥对农产品品质和生态环境的影响的研究,同时依据不同试验目的选用田间试验或模拟试验,注重构建通用性的水肥耦合模型。     

西南高原“旱三熟”地区不同覆盖栽培措施的土壤水分效应

在西南高原季节性旱区进行田间试验,研究不同覆盖栽培条件下"旱三熟"种植模式的农田土壤水分效应。研究表明,秸秆、地膜覆盖尤其是秸秆地膜二元覆盖有明显蓄集和保存土壤水的作用,土壤保蓄水度平均提高60.63%,覆盖能有效减少田间水分的无效蒸发,平均减少181.93 mm,使作物蒸腾系数和水分利用效率提高,平均提高19.84%和23.5%,而使作物耗水系数减小,平均减少18.26%,根区是作物耗水与土壤保蓄水的关键区域;农田水分变化沿土层可划分为3个层次,即0~30 cm土层为土壤水分变化活跃层和土壤贮水变化明显层、30~80cm土层为土壤水分变化次活跃层和土壤贮水变化显著层、80~100 cm土层为土壤水分变化相对稳定层和土壤贮水变化缓慢层。覆盖栽培可促进作物耗水量由田间无效蒸发耗水向有效的田间作物蒸腾耗水转化,使农田水分的有效性显著提升。     

控制性交替灌溉：一种新的农田节水调控思路

根据作物光合作用，蒸腾失水与叶片气孔开度的关系以及由土壤水分亏缺产生的作物水分胁迫信号对作物水分利用效率影响的机理，提出了控制性交替灌溉这样一种新的农田节水调控思路，阐述了这种节水调控方法的概念，原理和推广实施的方式。     

水泥硬壳覆盖对春玉米蒸腾与水分利用效率的影响

水泥硬壳覆盖对春玉米蒸腾，棵间土壤蒸发，作物生长发育状况，产量有水分利用效率的影响研究结果表明，水泥硬壳覆盖农田能减少土壤无效蒸发，提高玉米蒸腾效率，促进春播作物苗全苗壮，提高作物产量和水分利用效率。     

秸秆覆盖农田的小气候特征和增产机理研究

利用2000～2002年的试验资料和2002～2003年的示范推广资料,对秸秆覆盖的农田小气候和增产机理进行分析.结果表明:秸秆覆盖对农田近地层气温、空气湿度和地温均产生明显影响,但对风速的影响不明显;秸秆覆盖可使地表层显热通量增大,潜热通量和土壤热通量减小,从而使土壤蒸发受限;由于覆盖抑制土壤表面蒸发,使土壤水分无效消耗减少,增加前期土壤水分积累,有利于植株后期蒸腾,使水分消耗从物理过程向生理过程转化,从无效消耗向有效消耗转化,从而增加作物产量,提高水分利用效率.秸秆覆盖可使冬小麦增产8.08%～10.71%,水分利用效率提高3.5%～8.4%;夏玉米增产6.08%～11.97%,水分利用效率提高7.8%～14.4%.     

黄土高原半湿润区旱地一年两熟复种模式土壤水分效应

以冬小麦—夏闲种植模式为对照,比较了不同作物种植模式的土壤水分动态、作物耗水量及作物产量等指标。研究了旱地"一年两熟"种植模式的农田土壤水分动态及耗水规律,揭示了不同种植模式对土壤水分的影响机理。结果表明:旱地一年两熟种植模式具有较好的水分利用效率和经济效益,4种一年两熟种植模式的水分利用效率和经济效益较对照分别高48.4%~107.5%和62.3%~119.2%;发展旱地复种对土壤水分的影响程度有限,各复种处理与对照相比,水分差异主要存在于1 m以下的深层土壤;冬小麦—芝麻、冬小麦—大豆、冬小麦—玉米3种作物模式的全季度耗水强度仅较对照分别高0.05、0.07和0.09 mm/d。综合经济效益及土壤水分可利用性分析,冬小麦—玉米模式的经济产量、收益最佳,冬小麦—大豆则为水分生产效益次佳,但显著降低了对土壤水分的消耗。     

水稻旱作对其生长量和经济产量的影响

1998～1999年，研究了水稻旱作条件下，不同生育时期受水分胁迫后对作物生长量的影响。结果表明：不同指标对水分胁迫时期的敏感性不一，植株高度对抽穗期水分胁迫最敏感；单株绿叶面积和单株地上部干重对幼穗分化后期水分胁迫最敏感；根系干重和根冠比对幼穗分化前期水分胁迫最敏感；幼穗分化后期水分胁迫对经济产量影响程度最大，无效分蘖期水分胁迫对产量影响程度最小。     

Water deficit and corn productivity during the post-socialist period. Case study: Southern Oltenia drylands,Romania

Water deficit (WD) typically associated with drylands and poor land use currently represent a major limiting factor for agricultural systems in numerous regions of the world. The present study aims to analyze the relationship between water deficit and corn (Zea mays L) crop yields in southern Oltenia drylands. The study includes the post-1990 period, which is representative for Romania in terms of ample climate changes and poor land planning decisions affecting water resources. This analysis targeted the vegetation period of corn (April–September), the reference period covering a 14-year interval, from 1990 to 2003. The entire analysis was based on spatialized WD data (mm), obtained by interpolation methods used on climate data provided by regional weather stations, and agricultural yield data (tons/hectare/year), recorded in 113 administrative territorial units. Both data sets were analyzed in terms of interannual statistical relationships, established in compact climate zones delineated by Thiessen-Voronoi polygons. The results showed a clear statistical relationship between the two variables, with an average dependence of corn yields on water of approximately 65%. The range was from 55 to 78%, depending on region. The results showed an average yield decrease of 16.5 kg/ha/year for each mm rise of the WD, or loss of 1.65 t/ha/year when considering a deficit rise of 100 mm. Therefore, in the context of increasing future WD, urgent action is needed in order to reintroduce irrigation systems.     

Efficiency of Subsurface Drip Irrigation for Potato Production Under Different Dry Stress Conditions

Efficient water delivery systems such as drip irrigation can contribute towards increasing crop yield potential, improving crop water and fertilizer use efficiency. However, critical management considerations such as subsurface drip irrigation are necessary to attain improved irrigation efficiencies and production benefits particularly under arid regions. The objective of this study was to determine the effect of two irrigation methods, surface and subsurface drip irrigation combined with four irrigation levels, 100, 80, 60 and 40% of crop evapotranspiration on yield and yield components of potato grown on sandy soil. The field experiments were conducted in the years 2008 and 2009. In terms of soil water availability to plants, subsurface drip provided more favorable growth conditions for plant growth and maintained higher soil water content at the root zone, which resulted in a significant higher potato yield compared to surface drip irrigation. The difference between the two irrigation methods on yield components was concentrated on the mean tuber weight per plant, while no significant difference was found on the tuber number per plant. Reducing the amounts of applied water significantly decreased total potato yield and its components. Under subsurface drip irrigation, reducing amounts of applied water to 80% ETc gave comparable yield and yield components to surface drip at full irrigation supply, indicating that 20% irrigation water can be saved without affecting the potato yield. At all irrigation levels, subsurface drip recorded higher water use efficiency (WUE) over surface drip. Maximum value was observed at 40% ETc. Fertilizer use efficiency (FUE) was also higher under subsurface drip and reduced significantly under both irrigation methods with increasing water deficit. These results suggested that subsurface drip offers the potential of better water management with respect to saving and distribution of water in the root zone and to obtain maximum yield accompanied by highest water and FUE.     

基于改进的SEBS模型的作物需水量研究

为了探讨以蒸散发为基础的作物需水量情况,便于为农业生产提供数据支持,利用风云三号、风云二号气象卫星数据,结合自动站气象数据,基于改进的SEBS模型对山西省进行作物需水量研究。结果表明:通过与实测数据对比验证发现模型结果精度较高。山西省2012年3—9月全省日均作物需水量最大值出现在春季的5月份,为1.27 mm,其中,以单季作物为代表的晋东北和中西部日均作物需水量最大值均出现在5月,分别为1.05 mm和1.38 mm;以双季作物为代表的晋东南日均作物需水量最大值出现在5月和7月,分别为1.28 mm和1.23 mm。可见山西省作物需水量普遍以春季最大,其中尤以中西部突出,晋东北则相对最低。     

基于春玉米微咸水灌溉的水盐生产函数研究

在石羊河流域开展微咸水灌溉试验,综合考虑水分与盐分因素对春玉米生长的影响,以国际上通用的水分生产函数Blank模型和Jensen模型为基础进行作物水盐模型的构建,通过引入盐分胁迫因子,将水分生产函数转变为水盐生产函数。通过2009年和2010年春玉米不同矿化度微咸水灌溉试验,结合函数求解,探求春玉米各生育阶段的盐分敏感指数,得出春玉米的盐分敏感程度顺序为苗期>拔节期>抽雄灌浆期>成熟期。同时以交替灌溉试验进行验证,结果表明微咸水安排在盐分敏感程度小的生育阶段更有利于作物的生长。     

Bacterial and fungal diseases in the major potato-growing areas of Tunisia

In a two year survey of Tunisian rustic potato stores, the losses were nearly equally distributed between dry rots induced by Fusarium solani and watery wound rot or leak caused by Pythium aphanidermatum and P. ultimum. Symptoms of leak were different from those normally induced by Pythium spp. Surveys of the growing potato crop confirmed the prevalence of these pathogens, which caused wilt and internal vascular stem necrosis. Most rotted progeny tubers also exhibited leak symptoms caused by P. aphanidermatum. Hardly any Erwinia diseases were found in Tunisia. The incidence of diseased plants was significantly higher in fields with successive cultivation of solanaceous crops, which may be attributed to a high rate of soil infestation by wilt-inducing pathogens such as Pythium spp., F. solani and Verticillium dahliae. The health of seed potatoes also played a significant role, affecting the incidence of rot in potato stores as well as in the soil before plant emergence. Therefore, Tunisian integrated management programmes for potato diseases should focus on soil disinfestation with appropriate crop rotation as well as seed quality and treatments.     

砾石覆盖量对夏玉米作物系数及水分利用效率的影响

为评价半湿润易旱地区砾石覆盖对土壤贮水量、作物生长与产量及水分利用效率的影响,利用杨凌地区夏玉米2014年实测数据及气象数据,基于Penman-Monteith公式计算了砾石不同覆盖量下全生育期内参考作物蒸发蒸腾量,并根据FAO推荐的分段单值平均法,计算夏玉米各生育期作物系数,以及砾石不同覆盖量下作物水分利用效率。结果表明:砾石覆盖的保水效果主要体现在作物生长初期,拔节期最大砾石覆盖处理0~200 cm土壤贮水量较对照增大12.8%,后期由于冠层覆盖影响其效果减弱;夏玉米全生育期作物系数与覆盖量呈线性关系;覆盖量越大,不同生育阶段的作物系数也相应增加;叶面积和株高与作物系数有着较好的回归关系,可以对生育期内的玉米蒸散量进行预报;砾石覆盖可以缩短夏玉米生育期的天数,最大可缩短19 d;砾石覆盖能促进作物生长,提高作物产量,且在该试验覆盖量范围内,覆盖量越大,增产增效越明显,随覆盖量增加,各处理分别较对照提高4.65%~38.17%;作物水分利用效率随覆盖量的增大分别较对照提高2.94%~32.99%。     

基于FY-3D/MERSI数据的东北地区干旱监测方法研究

干旱是影响东北地区粮食安全的主要农业气象灾害之一，遥感技术是一种可便捷进行大范围干旱监测的手段。针对目前遥感干旱指数在作物生长发育过程中监测干旱的局限性和适用性等问题，以东北地区玉米和大豆等主要大田作物发育期为切入点，基于FY-3D/MERSI卫星遥感数据和地面土壤相对湿度实测数据，开展不同作物发育阶段干旱监测指数适用性分析，结合径向基神经网络方法，构建全时期和分时期土壤相对湿度反演模型，利用实测土壤相对湿度数据开展精度验证与对比分析。结果表明：风云三号MERSI传感器数据在干旱监测中具有可行性，表观热惯量(ATI)在低植被覆盖或裸土时效果较好，适用于作物冻土期、裸土期和播种～拔节期；水分指数(WI)适用于播种～拔节期、拔节～抽雄期和成熟期等植被生长时期；分时期土壤相对湿度反演模型精度高于全时期土壤相对湿度反演模型，前者监测精度在80.0%以上，比全时期模型精度提高了10%～25%,尤其在冻土期(3月),分时期模型反演精度达到了92.6%。基于作物生长时期和形态差异，选择最适宜遥感干旱指数建立分时期土壤相对湿度反演模型，提高了干旱监测的准确性和可靠性。     

基于水足迹的民勤县农作物耗水当量与气候响应评估

在阐述水足迹、水资源压力指数的基础上,计算了1991—2013年民勤县8种主要农作物(玉米、小麦、棉花、葵花、苹果、瓜类、蔬菜)蓝水需水量、总耗水当量和单位作物耗水当量,研究了这些作物在23年内总耗水当量和单位耗水当量的时间序列变化规律,并对比三种经济技术耗水分离模型,分离出4种典型作物(小麦、玉米、棉花、瓜类)单位气候耗水当量,最后选择逐步回归分析法探讨了作物气候耗水当量与相关气候因子之间的关系。结果表明:(1)民勤总耗水当量逐年增加,粮食作物总耗水当量变化最大,蔬菜、油料作物(葵花)次之,单位作物耗水当量在震荡中逐年递减;(2)HP滤波法为最优气候耗水当量分离模型,单位作物气候耗水当量趋势性不明显,序列期内震荡显著,且不同作物差异较大;(3)显著影响单位作物气候耗水当量的主要气候因子为5、6月份总降水量和7月份相对湿度,与生长期内气温要素相关性不强。可见,不同作物耗水变化的气候响应模式差异较大,整体受降水和温度的影响显著,但对全球气候变暖大趋势的响应机制尚不明确。     

Mapping the drivers of parasitic weed abundance at a national scale: a new approach applied to Striga asiatica in the mid-west of Madagascar

The parasitic weed genus Striga causes huge losses to crop production in sub-Saharan Africa, estimated to be in excess of $7 billion per year. There is a paucity of reliable distribution data for Striga; however, such data are urgently needed to understand current drivers, better target control efforts, as well as to predict future risks. To address this, we developed a methodology to enable rapid, large-scale monitoring of Striga populations. We used this approach to uncover the factors that currently drive the abundance and distribution of Striga asiatica in Madagascar. Two long-distance transects were established across the middle-west region of Madagascar in which S. asiatica abundance in fields adjacent to the road was estimated. Management, crop structure and soil data were also collected. Analysis of the data suggests that crop variety, companion crop and previous crop were correlated with Striga density. A positive relationship between within-field Striga density and the density of the nearest neighbouring fields indicates that spatial configuration and connectivity of suitable habitats is also important in determining Striga spread. Our results demonstrate that we are able to capture distribution and management data for Striga density at a landscape scale and use this to understand the ecological and agronomic drivers of abundance. The importance of crop varieties and cropping patterns is significant, as these are key socio-economic elements of Malagasy cropping practices. Therefore, they have the potential to be promoted as readily available control options, rather than novel technologies requiring introduction.     

The effect of total carbon on microscopic soil properties and implications for crop production

Soil structure is a dynamic property affected by physical, chemical, and microbiological processes. Addition of organic matter to soils and the use of different management practices have been reported to impact soil structure and crop production. Moderation in soil temperature and increases in microbial activity and soil water retention are often suggested as reasons for the rise in crop yield when organic matter is added to the soil. Less is known about the direct effect of changes in soil structure on crop production. A field experiment was conducted to study the effect of summer cover crop and in-season management system on soil structure. The experiment was a nested design with summer cover crop as the main plot and management system as the subplot. Summer cover crop treatments included cowpea (Vigna unguiculata L. Walp.) incorporated into the soil in the fall (CI), cowpea used as mulch in the fall (CM), sudangrass (Sorghum vulgare) incorporated into the soil in the fall (S), and dry fallow or bare ground (B). Management systems were organic (ORG) and conventional (CNV) systems. Lettuce (Lactuca sativa L.) and cantaloupes (Cucumis melo L.) were cultivated in rotation in the plots for three consecutive years using the same cover crops and management systems for each plot. Disturbed and undisturbed soil cores were collected at the end of the third year and used for laboratory experiments to measure physical, chemical, and hydraulic properties. Image analysis was used to quantify soil structure properties using a scanning electron microscope on thin sections prepared from the undisturbed soil cores. We found that total soil carbon was correlated with porosity, saturation percentage, and pore roughness. Pore roughness was correlated with crop production in general and with marketable production in particular. We found that the higher the complexity of the pore space, the more water retained in the soil, which may increase soil water residence and reduce plant water stress.