Correlations between the modelled potato crop yield and the general atmospheric circulation

Biology-related indicators do not usually depend on just one meteorological element but on a combination of several weather indicators. One way to establish such integral indicators is to classify the general atmospheric circulation into a small number of circulation types. The aim of present study is to analyse connections between general atmospheric circulation and potato crop yield in Estonia. Meteorologically possible yield (MPY), calculated by the model POMOD, is used to characterise potato crop yield. Data of three meteorological stations and the biological parameters of two potato sorts were applied to the model, and 73 different classifications of atmospheric circulation from catalogue 1.2 of COST 733, domain 05 are used to qualify circulation conditions. Correlation analysis showed that there is at least one circulation type in each of the classifications with at least one statistically significant (99%) correlation with potato crop yield, whether in Kuressaare, Tallinn or Tartu. However, no classifications with circulation types correlating with MPY in all three stations at the same time were revealed. Circulation types inducing a decrease in the potato crop yield are more clearly represented. Clear differences occurred between the observed geographical locations as well as between the seasons: derived from the number of significant circulation types, summer and Kuressaare stand out. Of potato varieties, late 'Anti' is more influenced by circulation. Analysis of MSLP maps of circulation types revealed that the seaside stations (Tallinn, Kuressaare) suffer from negative effects of anti-cyclonic conditions (drought), while Tartu suffers from the cyclonic activity (excessive water).     

基于降水利用比较分析的四川省种植制度优化

比较分析四川8个农业生态区典型站点及其主要种植模式的降水盈亏产量降低率、产量降低率风险指数、降水利用效率和降水经济效率。结果表明:(1)四川省不同区域、不同种植模式、不同作物及其不同生育阶段基于降水盈亏的产量降低率多年均值差异较大。区域分布上,雅安最低,仅23％,攀西最高,达50％以上,其余地区30％-40％;种植制度上,麦-玉-苕等旱三熟低于麦-稻等水旱轮作两熟制;作物种类上,冬小麦、冬油菜、秋播马铃薯等作物普遍高于水稻、玉米、棉花、红薯和大豆作物;生育阶段上,冬小麦、冬油菜、秋播马铃薯作物开花前后普遍较高,各种作物生育末期较低。(2)基于自然降水,攀西地区遭遇旱灾的风险极大,麦-玉-苕等旱三熟的产量降低率风险指数相对较小;雅安等盆地内部多数区域由于阶段性降水过多引起湿害偏重,导致麦-稻等水旱轮作两熟制略优于旱三熟。基于降水利用效率和降水经济效率,各地比较一致,较优的种植制度首先是麦(油、薯)-稻两熟制,其次才是麦(油)-玉-苕(豆)旱三熟。(3)综合旱涝灾害风险、降水利用效率和降水经济效率,以及复杂地形等因素,有较好灌溉条件的农田应以麦(油、薯)-稻水旱轮作两熟制为主,而无水源保障的旱地则以麦(油)-玉-苕(豆)旱三熟为主。     

Water,nutrients and slope position in on-farm pearl millet cultivation in the Sahel

In the Sahel, short periods of intra-seasonal drought, caused by unfavourable rainfall distribution, often have stronger effect on crop growth than fluctuations in annual rainfall. The interactive effects of nutrient deficiency and water shortage (during panicle initiation, flowering and grain filling) on yield and yield components of pearl millet (Pennisetum glaucum (L.) R. Br.), were studied on-farm along a cultivated slope, during three years with close to average annual rainfall. Grain yield was correlated to plant nutrient availability but not to annual rainfall, which was explained by the capacity of the crop to compensate for damage caused by water shortage during early growth phases. The performance of each yield component was positively correlated to cumulative rainfall during the growth phase when it was formed. Leaf area index (LAI) was very low, and leaf development followed rainfall distribution. Water and nutrients interacted during each growth phase for all fertility levels. Fertilised millet suffered less during water shortage at panicle initiation and at grain filling compared to non-fertilised millet. However, compared to favourable soil water conditions yield components were systematically lower for all treatments, indicating the synergistic effect of water and nutrients. The results suggest that water availability plays an exclusive role during flowering. Grain number dropped significantly due to water shortage and was similar for all treatments. Despite extremely high spatial variability in yields (varying with a factor 46 within the field), a significant slope effect was observed, of progressively increasing yields when moving downslope. Spatial redistribution of surface runoff resulting in higher soil water availability on lower slope positions, contributed to the yield gradient, which was reinforced for fertilised millet. For each drought period, yield components suffered systematically more upslope than downslope. This slope effect was smoothed out for manured millet, which indicates that manure increased soil infiltrability on crusted zones upslope. The slope interaction observed here – indicating that downslope (i) the risk for crop failure during droughts is lower and (ii) the response to fertilisers is greater – suggests that farmers can benefit relatively more from fertilisers applied in lower parts of the watershed. Taking advantage of spatial soil and water variability is an interesting system of low technology precision farming, which combined with water harvesting systems to master droughts, can constitute options for increased crop yields in the Sahel.     

气候变化背景下中国南方地区季节性干旱特征与适应Ⅵ.防旱避灾种植模式优化布局

南方地区是我国重要的农业种植区,季节性干旱严重影响该地区的农业生产.本文基于南方地区不同干旱分区中选取的13个典型地区1981-2007年气象资料和作物生育期、产量等资料,依据各地逐年降水量将其分为干旱年、正常年和丰水年3种不同降水年型,利用作物水分临界期需水量与降水量的耦合度、气象产量、单位面积产值以及全生育期的水分利用效率和降水量5个指标,对典型地区种植模式的综合效益进行评价,得到南方不同区域不同降水年型下的优化种植模式.结果表明: 半干旱区在干旱年型下,宜采取2种抗旱种植模式：马铃-玉米-甘薯和冬小麦-中稻-甘薯.半湿润区在干旱年型下,种植模式以冬小麦-中稻-甘薯最优,油菜-中稻-甘薯次之.在温润区(即典型的季节性干旱区),江南地区在3种年型下均以马铃薯-双季稻最优;西南地区宜搭配抗旱作物进行三熟制种植,如冬小麦-中稻-甘薯、冬小麦-玉米-甘薯、马铃薯-双季稻等.从最大程度利用水热资源角度考虑,三熟种植模式最优,以水旱轮作为主,丰水年型宜搭配水稻.     

雨强对黄土坡面土壤水分入渗及再分布的影响

基于典型黄土的坡地人工降雨实验,对比研究了降雨、入渗及再分布规律;以雨强为主要影响因素,分析了降雨入渗及水分再分布过程中水土物质迁移的定量关系.结果表明,雨强变化对黄土坡面降雨入渗及土壤水分再分布的微观水分运动过程具有重要影响.雨强增大时,入渗和再分布湿润锋均随降雨历时延长而逐渐增加,但水分再分布过程的湿润锋增加速率比入渗慢得多;入渗湿润锋与时间关系可用幂函数表示,同时可表示为雨强的幂函数关系.再分布湿润锋与时间也存在定量关系.雨强越大,初始和稳定的土壤水分入渗率越高,累积入渗量随降雨时间增加得越快.此外,雨强越大,坡顶与坡脚湿润锋深度差异越小,坡面再分布过程的土壤含水量在各层的差异和递减趋势越明显.     

雨强对黄土坡面土壤水分入渗及再分布的影响

基于典型黄土的坡地人工降雨实验,对比研究了降雨、入渗及再分布规律;以雨强为主要影响因素,分析了降雨入渗及水分再分布过程中水土物质迁移的定量关系．结果表明,雨强变化对黄土坡面降雨入渗及土壤水分再分布的微观水分运动过程具有重要影响．雨强增大时,入渗和再分布湿润锋均随降雨历时延长而逐渐增加,但水分再分布过程的湿润锋增加速率比入渗慢得多;入渗湿润锋与时间关系可用幂函数表示,同时可表示为雨强的幂函数关系．再分布湿润锋与时间也存在定量关系．雨强越大,初始和稳定的土壤水分入渗率越高,累积入渗量随降雨时间增加得越快．此外,雨强越大,坡顶与坡脚湿润锋深度差异越小,坡面再分布过程的土壤含水量在各层的差异和递减趋势越明显．     

The characteristics of certain varieties of potato with special reference to their suitability for drying

There is considerable varietal variation in the characteristics of the potato. The characteristics of any one variety of potato may be very greatly modified by environmental conditions. Rainfall and percentage dry matter may be inversely correlated, as may rainfall and yield in localities with a medium or high precipitation. There is an apparent correlation between time of maturity, percentage dry matter, and texture when cooked, late varieties having a higher percentage dry matter and a more floury texture than early varieties. It is a fundamental requirement of potatoes for drying purposes that they should not discolour on cooking. In addition the texture of the cooked potato should be suitable for the method of drying employed, and for the type of reconstituted product desired, and the percentage dry matter should be as high as is compatible with the foregoing conditions.     

Decreased precipitation exacerbates the effects of sea level on coastal dune ecosystems in open ocean islands

The alteration of fresh and marine water cycling is likely to occur in coastal ecosystems as climate change causes the global redistribution of precipitation while simultaneously driving sea‐level rise at a rate of 2–3 mm yr^?1. Here, we examined how precipitation alters the ecological effects of ocean water intrusion to coastal dunes on two oceanic carbonate islands in the Bahamas. The approach was to compare sites that receive high and low annual rainfall and are also characterized by seasonal distribution (wet and dry season) of precipitation. The spatial and temporal variations in precipitation serve as a proxy for conditions of altered precipitation which may occur via climate change. We used the natural abundances of stable isotopes to identify water sources (e.g., precipitation, groundwater and ocean water) in the soil–plant continuum and modeled the depth of plant water uptake. Results indicated that decreased rainfall caused the shallow freshwater table on the dune ecosystem to sink and contract towards the inland, the lower freshwater head allowed ocean water to penetrate into the deeper soils, while shallow soils became exceedingly dry. Plants at the drier site that lived nearest to the ocean responded by taking up water from the deeper and consistently moist soil layers where ocean water intruded. Towards the inland, decreased rainfall caused the water table to sink to a depth that precluded both recharge to the upper soil layers and access by plants. Consequently, plants captured water in more shallow soils recharged by infrequent rainfall events. The results demonstrate dune ecosystems on oceanic islands are more susceptible to ocean water intrusion when annual precipitation decreases. Periods of diminished precipitation caused drought conditions, increased exposure to saline marine water and altered water‐harvesting strategies. Quantifying species tolerances to ocean water intrusion and drought are necessary to determine a threshold of community sustainability.     

基于GIS的黄土丘陵沟壑区作物生产潜力模拟研究

从YIELD模型的来源、输入文件及基本参数,模型中作物生产力计算各个子模型以及计算流程4个方面作了简单的叙述,以黄土丘陵沟壑区典型小流域晋西狼窝沟为例,在地理信息系统（GIS）技术十,应用YILD模型对该流域的作物生产潜力进行了模拟,并从作物类型,地类,耕作措施及气候条件4个方面对影响该流域作物产量的因素进行了分析。结果表明,该模型对不同作物的模拟产量在总体上与实体产量基本相符合,表明模型可以应用于黄土丘陵沟壑区的作物产量模拟之中,对于不同地类来说,坝地的土壤水分和以力条件明显高于梯田和坡耕地,因而坝地的模拟产量地高于梯田和坡地,但三者之间的差距没有实测产量显著,耕作措施是提高作物生产力的有效途径,对地膜覆盖,梯田以及施肥等耕作措施的模拟产量表明,这3种耕作措施均能有效的物生产力;其产量提高率均平均在85％以上,其中以施肥对作物的增产作用最大,增产率高达95％,,这与实测产量资料基本一致;气候条件是影响作物生产的直接因素,模拟结果表明模型对降水量和温度等气候条件十分敏感,不同年份降水量和温度的差异将直接导致作物生产力的显著不同。对YIELD模型的模拟结果分析表明,该模型可以有效地应用于黄土丘陵沟壑区的作物生产潜力研究。     

北方旱作区沟垄二元覆盖技术研究进展

北方旱作区降水稀少,水分不足是限制作物生长的主要因素,沟垄二元覆盖技术可进一步提高降水的利用效率和作物生产水平,在国内外已备受关注.为深刻理解中国北方旱作区沟垄二元覆盖技术模式及研究进展,本文就沟垄二元覆盖技术的概念、研究现状、配套农机具、技术模式及其土壤生态与作物效应进行了综述;在总结现有研究的基础上,归纳了典型旱作区沟垄二元覆盖技术模式的类型、作业操作及应用效果;科学评价不同沟垄二元覆盖技术下土壤与作物的生态效应;指出了目前沟垄二元覆盖技术研究中所存在的问题,并提出相应的建议.综合国内外沟垄集雨栽培技术的研究进展,提出沟垄二元覆盖模式及技术体系今后的重点研究方向:1)建立适合北方不同旱作类型区及不同作物的垄沟比;2)重视土壤水分与温度、肥力等其他因子耦合性研究;3)探索最佳环保型覆盖材料;4)加强沟垄二元覆盖模式及体系的技术评价、技术推广与配套机具设计等方面的研究.     

辽西褐土施肥及养分循环再利用中长期试验Ⅴ.不同降水年景作物产量对施肥的反应和水肥交互作用

通过比较平水年 ( 1996年 ,作物生长期降水 4 5 6mm)和丰水年 ( 1998年 ,作物生长期降水 5 98mm)作物对施肥的增产反应 ,初步估算了辽西半湿润 半干旱地区水肥交互作用对作物增产的贡献 .结果表明 ,施氮肥并增加水分供给 (降水增加 ) ,作物增产 (玉米、大豆 ) 30 5 6kg·hm-2 ,其中 1996kg·hm-2 来自水肥交互作用 ,占 6 5 .3% .施NP和堆肥并增加水分供给 ,作物增产 4 70 3kg·hm-2 ,其中 15 5 4kg·hm-2 来自水肥交互作用 ,占 33% .     

陇东黄土旱塬作物组合系统农田耗水规律研究

本文根据１９８８－１９９１年陇东黄土旱塬作物组合模式（即作物轮作与复种模式）田间试验土壤水分测定资料,对作物组合系统中主要组分作物田间耗水量及其构成特征、变异规律及农田土壤水分的利用程度进行了研究,并探讨了不同作物组合系统的田间耗水量及其构成特征。结果表明,不同作物组合系统的田间耗水量及其构成特征存在明显差异;作物田间耗水量是一个动态变量,因作物种类、降水年型等不同而异,并与生育期有效降水量呈显著正相关;来自播前土壤有效储水的土壤供水量对秋播作物冬小麦和冬油菜生育期水分不足有重要补偿作用,是维持其较高的生产稳定性的关键原因;无论丰水年还是欠水年,冬小麦、玉米、谷子和马铃薯４种主要作物在农田水分利用程度上均存在一定差异。     

南方丘陵区不同坡地利用方式土壤水分动态

土壤水分异质性的存在对各种水文过程和土壤形成过程均有显著的影响,了解土壤水分的异质性对理解和预测土壤水分过程具有重要意义.应用时域反射仪(TDR)土壤水分定位监测方法,研究了南方丘陵区不同坡地利用方式土壤水分动态及其影响因子.结果表明:3种坡地利用方式土壤水分变化具有明显的季节特征,杜仲人工林土壤蓄水量最高,荒山草坡次之,坡耕地最低.植物非生长季节土壤含水量均值高于生长季节,生长季节土壤水分消耗大于补给,非生长季节土壤水分补给大于消耗;干季和湿季两个时段3种坡地利用方式土壤含水量垂直变化趋势具有相似性,其土壤含水量差异不显著.3种坡地利用方式土壤蓄水量与太阳辐射量和大气温度表现为负相关性,与降雨量、大气相对湿度和饱和水气压差表现为正相关性,降雨量是其最直接的影响因子,其次是温度.雨季单次降雨后土壤蓄水量与雨后干旱天数存在显著的线性负相关性(P<0.05),土壤水分损失率与干旱天数存在双曲函数关系(P<0.05), 随着干旱天数的增加,土壤水分损失率趋于平缓.雨季单次降雨后持续干旱条件下3种坡地利用方式土壤剖面含水量呈递减的变化趋势,杜仲人工林土壤水分损失率系数最高,荒山草坡次之,坡耕地最低.     

Principles of Natural Regeneration of Tropical Dry Forests for Restoration

Tropical dry forests are the most threatened tropical terrestrial ecosystem. However, few studies have been conducted on the natural regeneration necessary to restore these forests. We reviewed the ecology of regeneration of tropical dry forests as a tool to restore disturbed lands. Dry forests are characterized by a relatively high number of tree species with small, dry, wind‐dispersed seeds. Over small scales, wind‐dispersed seeds are better able to colonize degraded areas than vertebrate‐dispersed plants. Small seeds and those with low water content are less susceptible to desiccation, which is a major barrier for establishment in open areas. Seeds are available in the soil in the early rainy season to maximize the time to grow. However, highly variable precipitation and frequent dry spells are important sources of mortality in seeds and seedlings. Collecting seeds at the end of the dry season and planting them when soil has sufficient moisture may increase seedling establishment and reduce the time they are exposed to seed predators. Germination and early establishment in the field are favored in shaded sites, which have milder environment and moister soil than open sites during low rainfall periods. Growth of established seedlings, however, is favored in open areas. Therefore, clipping plants around established seedlings may be a good management option to improve growth and survival. Although dry forests have species either resistant to fire or that benefit from it, frequent fires simplify community species composition. Resprouting ability is a noticeable mechanism of regeneration in dry forests and must be considered for restoration. The approach to dry‐forest restoration should be tailored to this ecosystem instead of merely following approaches developed for moister forests.     

陕北黄土区大气降水同位素特征及其水汽来源

为探究陕北黄土区大气降水氢氧稳定同位素特征及其水汽来源,以陕西省定边县为研究区,于2018—2020年共收集107次降水事件样品,分析了该区降水中δ¹⁸O和δ²H组成特征,并探讨了不同季节的水汽来源。结果表明: 定边氢氧稳定同位素存在明显的季节变化,湿季(6—9月)偏贫化,干季(4—5月、10—11月)偏富集;氘盈余呈现干季高湿季低的特点。当地大气降水线方程为δ²H=7.35δ¹⁸O+4.19 (R²=0.96, P<0.01),斜率和截距均小于全球大气降水线,表明该区域降水受到一定程度的蒸发分馏影响。全年降水同位素组成表现出温度效应,而湿季和干季差异较大,仅干季存在温度效应,湿季降水同位素组成可能受温度和降水量的共同影响。HYSPLIT气团轨迹模型表明,干季水汽主要来自大西洋和极地北冰洋地区,而湿季降水主要来自印度洋和太平洋,同时受到西风带的影响。     

漓江上游典型森林植被对降水径流的调节作用

利用野外同步长期定位观测林外降雨、地表径流和河川径流的方法,对漓江上游典型森林植被的生态水文过程进行观测研究。结果表明:1)流域降水年内分配极不均匀,50a年降雨量总体变化趋势不明显。林冠截留受林外降雨特征的影响,也与植被类型密切相关。2)地表径流平均滞后时间为70 min。在连续降雨的情况下,降雨滞后效应不再明显,甚至出现地表径流与降雨同步的现象,小降雨可能产生大的地表径流,从而加大流域在雨季发生洪灾的风险。3)湿季径流系数略大于旱季,干季降水量减少,且森林植被消耗大量水分,减少了枯水期径流的产生,增大发生旱灾的风险。森林植被延长河川径流持续时间,使一次持续18 d的降水过程形成的径流,在降水停止后能延续24 d。降雨后退水持续时间与前期降水及后期降水叠加有关。目的为揭示漓江上游森林植被对降水径流的调节作用,客观评估漓江上游水资源潜力、加强流域水资源管理和森林经营提供科学依据。     

Applying hydraulic lift in an agroecosystem: forage plants with shoots removed supply water to neighboring vegetable crops

When a plant encounters spatially heterogeneous soil moisture within its root system, usually drier surface and moister subsurface soils, water can move between these layers through the root system, a plant process known as hydraulic lift or redistribution. The water thus transferred is available not only for the plant itself but also for its neighbors. We examined application of this process as a possible biological irrigation tool. As ??donors??, we used perennial forage plants with their shoots removed to minimize the effect of light-interception by them on the ??receiver?? plants growing alongside them. In a horizontally split-root experiment, where an upper container was filled with sand and a lower one with water, superior donor species could maintain the upper sand in a fully hydrated condition for several weeks, increasing stomatal conductance in the receivers. The effects were also confirmed in a water-limited agricultural field, as significant differences were found in canopy temperature and yield in neighboring crop plants in the presence or absence of donor root systems. These results suggest that deep-rooting associate plants with their shoots removed function as an irrigation tool and improve crop production in water-scarce environments.     

基于卫星降水产品的华北北纬38°带降水氢氧同位素时空特征及水汽来源

降水氢氧同位素的变化程度对反演降水水汽来源和认识蒸发作用的强弱有重要作用;结合高时间分辨率的卫星降水产品能够提高反演水汽来源的准确性,更清晰地说明水汽团的运移路径.本研究以位于华北北纬38°带的中国科学院太行山站(山区)、栾城站(山前平原)和南皮站(滨海低平原)2015-2018年降水氢氧同位素为对象,分析该区域降水水...     

江西红壤坡地柑橘园生态水文特征及水土保持效益

在江西省水土保持生态科技园对标准柑橘试验小区生态水文特征进行9年的定位观测,设置7个处理,研究柑橘园生态水文特征及水土保持效益.结果表明： 7个处理的平均减流率和减沙率分别为78.5%和77.2%,其中,林下百喜草(Paspalum natatu)带状覆盖、百喜草全园覆盖和水平梯田+梯壁植草减流率较高,分别为94.8%、94.3%和92.5%;柑橘清耕地减流率较低,为33.1%;林下套种黄豆和萝卜减流率居中,为66.0%和77.5%,且横坡耕作优于纵坡耕作.对2009-2010年发生的43场平均降雨量为20.07 mm的雨水柑橘林冠再分配格局进行观测,穿透降〖JP2〗雨量平均为9.15 mm,树干茎流量平均为4.72 mm,林冠截留量平均为620 mm,分别占林外降雨量的44.7%、25.7%和29.6%.随着林外降雨量的增大,林冠层的穿透雨量、茎流量呈递增趋势.当降雨量<10 mm时,树冠截留率与林外降雨之间呈显著的线性负相关;当降雨量>10 mm时,二者之间的相关性不明显.柑橘枯落物的持水率与浸水时间呈对数回归关系,最大持水率达326%.合理的林下植被配置对柑橘果园的水土保持具有重要作用.     

次降雨条件下坡度对坡面产流产沙的影响

以野外径流小区的次降雨产流产沙数据为基础,对不同次降雨条件下坡面产流产沙随坡度的变化规律进行研究.结果表明:降雨性质的差异对坡面产流随坡度而变化的影响较小,在研究区的6场次降雨中,坡面产流量随坡度的变化规律基本一致,坡面径流量均随坡度增大而增大,但坡面径流量随坡度增加而增加的趋势较弱,这主要由降雨量与入渗量之间的转化程度所决定;次降雨性质对不同坡度的坡面产沙规律有重要影响,一般情况下存在临界侵蚀坡度,但临界坡度不是唯一值,而是随着降雨特性的不同而不同,临界侵蚀坡度随径流量的增大而增大,临界坡度较大时,坡面产沙量随坡度变化而变化的趋势也往往较大.