Characterization of rainfall - microrelief interactions with runoff using parameters derived from digital elevation models (DEMs)

The main objective of this study was to investigate how the interactions between rainfall energy and microrelief affect soil surface sealing and runoff. Furthermore, several roughness indices and geostatistical procedures were tested for their ability to characterize microrelief.Runoff boxes filled with soil from the plough layer of a silty Luvisol were subjected to simulated rainfall. Two types of microrelief (rough and fine) were tested at two rainfall intensities (30 and 60 mm/h). A photogrammetric technique was used to develop digital elevation models (DEMs) of the soil surface before and after rainfall with a resolution in height of 0.2 mm and a grid spacing of 2 mm.The random roughness coefficient according to Currence & Lovely (1970) was found to be sensitive to surface microrelief variations. Semivariograms of the data indicated that big clods were the main elements determining microrelief and the ratio of total surface are to map area. The observed variations in runoff as a function of microrelief were best explained by rainfall energy per total surface area and by the relative contribution of the effective normal component of kinetic energy with respect to the impact angle of raindrops. Microdepression storage was only 0.6 mm or less and was found to be negligible in terms of runoff.     

Changes in microrelief and their effects on infiltration and erosion during simulated rainfall

The erosivity of soils under a given rainfall energy appears to vary greatly among soil orders, probably reflecting differences in clay composition and organic matter content. This study was conducted to quantify microrelief, infiltration, and sediment yield changes during three consecutive simulated rain events on a Udic Haploboroll and a Typic Hapludalf from Minnesota, and a Mollic Kandiudalf, and Typic Palehumult from Uganda. Air dry aggregates (< 5 mm) were packed in 19 1 containers tilted to a 5% slope and were subjected to three consecutive high energy rain storms (63 mm h⁻¹) for a duration of 1 h. Runoff and sediment were continuously monitored during a storm. Infiltration was measured by continued weighing of the soil and containers. An automated non-contact laser relief meter was used to measure changes in soil roughness initially and after each storm. Soil surface roughness decreased during the rain events indicating that aggregate breakdown was the dominant process in seal formation. For example, random roughness decreased form 5.9 to 4.0 mm on Barnes loam and from 9.7 to 6.9 mm on Renova silt loam with cumulative rainfall of 0 and 126 mm. These infiltration rates indicated that the Barnes Loam (Haploboroll) and Kabanyolo clay (Kandiudalf) were unstable soils while Kachwekano clay (Palehumult) and Renova silt loam (Hapludalf) were quite stable. Final infiltration rates after 3 consecutive rainfalls on Kachwekano clay (15 mm h⁻¹) and Renova silt loam (13 mm h⁻¹) [the stable aggregate soils] were significantly higher than those of Barnes loam (4 mm h⁻¹) and Kabanyolo clay (3 mm h⁻¹). For the two stable soils a high infiltration rate on a rough surface was maintained until aggregate breakdown occurred and runoff began. Sediment yield from Barnes loam (29 kg m⁻²) and Kabanyolo clay (28 kg m⁻²) was significantly greater than soil loss from Kachwekano clay (0 kg m⁻²) and Renova silt loam (6 kg m⁻²). The microrelief method to quantify aggregate stability is an improvement over wet sieving and other related measurements because of its rapidity and because the statistical quantification can be linked to physical processes.     

Soil surface densification under simulated high intensity rainfall

The formation of surface crusts in agricultural soils has adverse effects on seedling emergence and infiltration and causes excessive water loss by runoff. Changes in soil surface characteristics of Zamora soil were examined under high intensity (76.2 mm/hr) simulated rainstorms A hard, dense, several-cm-thick, consolidated layer developed on the soil surface upon drying. The thickness and bulk density of this layer were strongly related to rainfall duration. A strong exponential function was found between the thickness of the consolidated layer and the soil wetted depth. Soil surface strength was strongly correlated with rainfall duration and with the initial bulk density of the soil despite the marked change in the density of the consolidated layer. The largest changes in both strength and bulk density occurred within the first 10 min of the rainstorm. Mechanisms known to be responsible for crusting appear to partly hold for the densification process, but they do not adequately explain the deeper consolidation. Particle reorganization and close-packing associated with settling under saturated or near-saturated conditions appear to provide more logical mechanisms. The relative change in bulk density was inversely correlated with the initial soil bulk density. Measurements of soil strength with a small penetrometer probe indicated an agreement between surface strength and the cohesion of the consolidated layer as determined by a triaxial shear test. Temperature of drying had slight, but mostly inconsistent effects on the strength and density of the consolidated layer. Soil densification was also found to markedly decrease the infiltration rate. The physical properties of both the consolidated layer and the subsoil, however, appeared to control the infiltration process.     

花生复合系统土壤水分动态与平衡特征研究

花生复合系统是促进低丘红壤区农业水分资源综合利用的重要耕作方式,其在不同时段水分动态、水分平衡和利用过程差异值得进一步探索。土壤表层采用15 bar的先进负压计监测,结合定位法于2001—2003年监测收集了花生生长季花生复合系统、花生单作田间土壤水分、地表径流、降雨资料,分析了花生复合系统对土壤水分动态、降雨影响和水分平衡各要素的影响。分析表明,土壤10 cm与 60 cm水分单作花生地与复合系统在雨季无明显差异,但受降雨过程影响。旱季单作花生10 cm水势降到最低值-344.0 kPa,复合系统水势最低值为-50.6 kPa,60 cm单作花生地水势数值也低于复合系统花生地,旱季复合系统能减少土壤表层的蒸发。3年土壤水分周期动态可分为3个阶段,即水分盈余期、水分消耗期、水分稳定期。花生复合系统旱季表现出较强的耗水作用,2001年7月贮水量减少108.8 mm,2002年8月贮水量减少111.7 mm,2003年7月贮水量减少105.5 mm。花生复合系统平均渗漏量低于花生单作62.2 mm,平均贮水量变化低于花生单作41.8 mm。桔树与花生作物在旱季水分利用方面没有明显的竞争作用,花生复合系统系统的表土水分保持作用和生态效应明显。     

Polysaccharide and salt effects on infiltration and soil erosion. A rainfall simulation study

Seals forming at the soil surface during rainstorms reduce water penetration and increase runoff in many arid and semi-arid regions. The effect of surface application of an anionic polysaccharide (designated F-Ac), synthesized by the filamentous cyanobacterium Anabaenopsis circularis PCC 6720, on infiltration rate (IR), runoff and erosion of three soils during simulated rainstorms, was studied. The interaction between F-Ac and electrolyte concentration at the soil surface was studied by using distilled water (DW) or tap water (TW) or by spreading phosphogypsum (PG) on the soil surface. F-Ac added at the rate of 3.4 kg ha⁻¹ together with PG at the rate of 5 t ha⁻¹ was the most efficient treatment in improving infiltration and reducing runoff and erosion. This treatment reduced runoff, from the three soils studied, from 65–80% in the control to 14–24%. Soil loss was reduced from 3.6–4.5 Mg ha⁻¹ in the control to 0.5–1.3 Mg ha⁻¹ in the treated soils. DW treatment, singly and in combination with F-Ac, was quite inefficient in preventing seal formation and in reducing runoff and soil loss. Adding F-Ac with TW maintained final IR and runoff levels intermediate between those of F-Ac with PG and those of F-Ac with DW. Electrolytes in the soil surface which flocculated soil clay, enhanced the beneficial effect of F-Ac on aggregate stability and thus greatly reduced water and soil losses. The efficacy of F-Ac as a stabilizing agent (i.e., soil conditioner) wore out during three consecutive storms of 60 mm each.     

不同农田管理措施旱地玉米土壤水分特征分析

试验研究了不同农田管理措施下旱地玉米的土壤水分特征。结果表明,秸秆整秆全覆盖、微孔地膜覆盖较秸秆粉碎还田和常规种植能提高土壤水分,增加降水的入渗深度,减少土壤耗水量,其顺序为秸秆整秆全覆盖>微孔地膜覆盖>秸秆粉碎还田>常规种植。受基础土壤水分不同和降雨较少的影响,玉米生育前期不同农田管理措施土壤水分差异不大,8月份充足的降水后,各措施充分显示了其蓄水保墒的作用,其中,9月份秸秆整秆全覆盖0~120 cm土壤贮水量为248.2 mm,较常规种植增加32.1 mm;降水入渗深度为120 cm,较常规种植增加25 cm。     

山西暴雨的天气气候学分析

利用1957—2009年NCEP常规气象资料,从暴雨时空分布特征等角度,结合天气动力学、统计学等方法,对山西暴雨进行天气气候的分析研究。结果表明：（1）从气候学上讲,中条山东部是山西暴雨的极值中心,降水极值中心强度到达94 mm。发生暴雨频次最多的地方主要位于太行山南麓延伸至中条山东部的晋东南和晋南地区。另一个出现暴雨次数比较多的地区位于五台山附近,显示出山西特殊地形对山西暴雨的增幅作用。（2）50多年来,山西暴雨次数有着显著的年代际变化特征,1957—1982年,山西暴雨处于发生次数较多阶段,1983—2002年,山西暴雨处于次数较少阶段;2003年以后,山西又处于暴雨明显增加阶段。（3）形成山西暴雨的暖湿气团可能是南亚季风向北伸进的结果,暴雨发生日,320 K等墒面上,在山西附近形成一个高位涡中心,其和来自低纬度的暖湿空气,在山西附近相交绥,导致山西暴雨的产生。     

团粒结构对黄绵土溅蚀速率和结皮形成的影响研究

为弄清团粒结构在土壤结皮形成过程所起的作用,笔者通过人工模拟降雨溅蚀试验,测定土壤溅蚀速率,同时采样制作土壤切片,分析不同直径团粒对黄绵土溅蚀速率和结皮形成的影响。结果表明：0.15 mm≤D＜2.0 mm和D＜0.038 mm的团粒土壤较易形成结皮,在降雨历时5 min时,土壤表面有结皮形成,随着降雨的继续,土壤表面结皮形成趋于完善;而中度直径0.038 mm≤D＜0.15 mm的团粒土壤不易形成结皮,在降雨历时5 min时,土壤表面都没有结皮形成。在团粒直径范围是0.105 mm≤D＜0.22 mm,随着土壤团粒直径的减小,土壤的溅蚀速率逐渐增加,直径位于0.096~0.15 mm之间的团粒结构土壤的溅蚀速率达到最大,随后,随着土壤团粒直径的减小,土壤溅蚀速率逐渐降低。     

不同施肥模式对砂姜黑土团聚体特征及有机碳的影响

采集32年砂姜黑土长期定位试验不施肥(CK)、单施化肥(NPK)、单施有机肥(M)、有机肥与化肥配施(MNPK)和高量氮肥下有机肥与化肥配施(HMNPK)处理耕层土壤,研究砂姜黑土区麦玉轮作系统中总有机碳、团聚体组成及不同粒径团聚体中有机碳含量对长期不同施肥模式的响应。结果表明,长期不同施肥方式显著影响土壤不同粒径团聚体分布及其有机碳含量。有机肥施用对表层土(0—10 cm)1—0. 5 mm、0.5—0.25 mm干筛团聚体和< 0.25 mm微团聚体含量的提高有促进作用。耕层土壤水稳性团聚体主要分布在1—0.5 mm、0.5—0.25 mm和<0.25 mm粒径中,施肥处理对各粒级水稳性团聚体含量没有显著影响。长期施肥显著提高了表层土1—0.5 mm和0.5—0.25 mm干筛中团聚体有机碳含量,HMNPK的增幅最高。施用有机肥对提高土壤水稳性团聚体有机碳含量有积极作用,尤其对1—0.5 mm、0.5—0.25 mm和<0.25 mm粒径水稳性团聚体有机碳含量的提高有显著影响,且均为M处理提高幅度最大。砂姜黑土区麦玉轮作条件下,长期有机肥施用可提高砂姜黑土土壤总有机碳含量、中团聚体数量以及有机碳含量,有利于改善土壤物理性状、提升地力。     

近44年福建省暴雨的时空分布及对农业生产的影响

通过对福建省66个站近44年的历年降水资料分析,阐述暴雨、大暴雨、特大暴雨的时空分布特点及对农业生产的影响。结果表明福建各类型暴雨主要发生在雨季和夏季,雨季为暴雨的第一高峰期;夏季为大暴雨和特大暴雨第一高峰期;秋冬季和春雨季的各类暴雨出现频率较小;暴雨的地理分布相对均衡,而大、特大暴雨的高发区在沿海地区。各类型暴雨以暴雨为主,但给农业生产造成严重损失的通常是大、特大暴雨。     

Development of an irrigation regime for winter wheat to save water resources by avoiding irrigation at anthesis stage

Latest published information is limited on agronomic responses of winter wheat to irrigation quantity and the necessity of irrigation at the anthesis stage. This study was conducted to (1) evaluate winter wheat yield, water use, assimilate redistribution and economic benefit with respect to water input and (2) quantify relationship between water input and yield to develop a standard for withholding irrigation at anthesis. A 4-year long field experiment was conducted to evaluate winter wheat water use, yield formation pathway and farmers' income under three irrigation regimes: rainfed, irrigation at sowing and jointing (SJ-W) and irrigation at sowing, jointing and anthesis (SJA-W). The yield formation pathway was correlated with the water-induced variation in assimilate redistribution and accumulation. Throughout the experimental period, wheat yield was 19–38% lower in rainfed than that under other irrigation treatments. Moreover, SJ-W treatment substantially increased biomass accumulation at anthesis, accelerated assimilate redistribution in vegetative organs and eventually resulted in a similar wheat yield to that of SJA-W. Simultaneously, the SJ-W treatment had lower irrigation water, reduced additional irrigation cost, suppressed yield loss and obtained a similar farmer's net income to the SJA-W treatment. Water-induced variations in yield were determined by irrigation, rainfall and soil water storage. SJ-W plots receiving 204–331 mm water input (rainfall + irrigation) before anthesis and holding 549–587 mm soil water during anthesis stage achieved higher irrigation water use efficiency and yield relative to the rainfed and SJA-W plots. In contrast, water input under rainfed plots exceeded 200 mm before anthesis, limiting yield substantially even when seasonal soil water consumption exceeded 160 mm. Developing a standard for withholding irrigation at the anthesis stage should incorporate 204–331 mm of water input (rainfall + irrigation) before anthesis and 549–587 mm soil water storage at anthesis, which could achieve a high wheat yield and save water resources.     

渗水地膜研制及其应用

根据旱地农业生态系统特征, 提出了小雨资源有效化是旱地农业增产的突破口; 同时提出了“微孔自调节原理”和“线性小孔(不)扩散原理”组成的“单向渗水原理”, 并研究发明了“渗水地膜”。 通过在山西省以及北京、 河北、 宁夏、 甘肃等不同生态区渗水地膜覆盖试验, 结果表明： 渗水地膜具有渗水、 保水、 调温、 微通气     

不同降水年型旱地小麦休闲期耕作的蓄水增产效应

为明确旱地小麦通过休闲期耕作实现蓄水增产的技术途径, 2009-2012年连续3个小麦生长季, 在山西闻喜县进行了休闲期深翻、深松或无耕作的田间试验, 以明确不同耕作措施对土壤水分变化、小麦产量形成的影响。结果表明, 深翻和深松处理播种期0~300 cm土壤蓄水量增加, 枯水年增加63~91 mm, 平水年增加41~70 mm, 丰水年增加54~74 mm, 尤其在枯水年和丰水年生育后期蓄水效果仍显著, 休闲期土壤蓄水效率显著提高, 枯水年提高147%~205%。深翻和深松处理在枯水年和丰水年可促进小麦生育后期吸收300 cm土层土壤水分, 使产量和产量构成因素显著提高, 尤其在枯水年产量提高34%~45%。在平水年, 穗数、穗粒数和产量显著提高, 且在平水年和丰水年深翻和深松处理对产量构成因素中的穗数影响最大。深翻和深松处理后降水生产效率和水分利用效率显著提高。不同降水年型休闲期耕作条件下, 穗数与播种至拔节期120~180 cm、拔节至开花期60~120 cm土层土壤贮水减少量关系密切, 穗粒数与播种至拔节期60~120 cm土层关系密切, 产量与拔节至开花期60~120 cm、开花至成熟期 120~180 cm土层关系密切。总之, 在本研究条件下, 旱地小麦休闲期深翻或深松耕作有利于蓄积休闲期降水, 改善底墒, 尤其枯水年的效果更为明显; 有利于增加土壤水分, 促进小麦向深层吸收土壤水分, 优化产量构成, 实现增产。在枯水年和平水年, 以休闲期深翻效果较好, 在丰水年以休闲期深松效果较好。     

近50年菏泽市暴雨气候特征

为了揭示菏泽市暴雨气候特征,笔者利用菏泽市9个气象站50年的暴雨资料进行了研究。选取1960—2009年历年3—11月菏泽市9个站的逐日（20:00—20:00）降水资料,采用多种统计方法分析菏泽市多年暴雨气候规律。结果表明：菏泽市暴雨年际变化及年代际变化离差较大,60年代暴雨较多,之后较少,2000年之后又呈增长趋势。并且在1974年和2003年发生明显突变。1974年以前和2003年以来暴雨发生次数较多,1975—2002年期间暴雨发生次数较少。暴雨发生有明显的区域性,区域分布呈东南向西北递减的趋势,并且南北易受不同系统影响。本研究对做好暴雨预报,开拓气象服务,防灾减灾有一定参考作用。     

Effect of Rainfall Collecting with Ridge and Furrow on Soil Moisture and Root Growth of Corn in Semiarid Northwest China

A plastic‐covered ridge and furrow farming of rainfall collecting (RC) system were designed to increase water availability to corn for improving and stabilizing agricultural production in the semiarid Loess region of northwest China. This system comprised two elements: the ridge mulched by plastic film that acts as a rainfall harvesting zone and the furrow as a planting zone. To adopt this system for large‐scale use in the semiarid region and bring it into full play, it is necessary to test the appropriate rainfall range for RC farming. A field study (using corn as an indicator crop) combined with rainfall simulation was conducted to determine the effect of RC on soil moisture, root characteristic parameters and the yield of corn under three different rainfall levels (230, 340 and 440 mm) during the growing seasons of 2006 and 2007. The results indicated that with the rainfalls ranging within 230–440 mm, the soil moisture at 0–100 cm depth for RC system in furrows was significantly higher (P < 0.05) than that of conventional flat (CF for control) practice. At 100–200 cm soil depth, there was no significant difference (P > 0.05) between soil moisture in the RC₂₃₀ plots and in the CF₂₃₀ plots during the corn growing seasons, while the soil moisture both in the RC₃₄₀ and RC₄₄₀ plots were significantly higher (P < 0.05) than those in the CF₃₄₀ and CF₄₄₀ plots. The root length, root surface area, root volume and root dry weight for RC₂₃₀ and RC₃₄₀ plots all significantly increased (P < 0.05) compared with CF₂₃₀ and CF₃₄₀ plots, but these root characteristic parameters at 440 mm rainfall slightly decreased compared with those of CF practice. Compared with the CF_230–440 pattern, the increasing amplitude of grain yield under the RC_230–440 pattern diminished with the rainfall increase and there was no obvious yield‐incrementing effect (P > 0.05) between two patterns at 440 mm rainfall in 2006. In comparison with these two farming practices, the RC system not only improved soil moisture of dry farmland, but also promoted the development of corn root systems when the rainfall ranged between 230 and 440 mm. Thus, it could be concluded that the optimal upper rainfall limit for the RC system is below 440 mm in the experiment. For corn, the adoption of the RC practice in the 230–440 mm rainfall area will make the system more effective during the whole growth period and offer a sound opportunity for sustainable farming in semiarid areas.     

黑龙江省夏季降雨量及暴雨时空分布特征研究

利用黑龙江省80个气象站夏季(6-8月)逐日降水资料,分析近55年(1961-2015年)黑龙江省夏季降雨量和暴雨的变化特征,为粮食生产提供科学依据。[方法]从夏季降雨量、降雨量变化趋势、暴雨次数、暴雨变化趋势等方面,利用趋势系数等统计方法和GIS空间插值技术,分析黑龙江省夏季降雨量和暴雨的时空分布特征。[结果]结果表明黑龙江省夏季降雨量在中部的小兴安岭和张广才岭西部地区最高,在360mm以上,东部三江平原和西部松嫩平原地区最低,在300-320mm之间。夏季降雨量在松嫩平原和大兴安岭地区呈增加趋势,小兴安岭和三江平原地区呈减少趋势。全省夏季平均降雨量呈减少趋势,平均每10年减少2mm,20世纪70年代平均降雨量最低,80年代最高。小兴安岭西南部和张广才岭西部地区平均暴雨日数最多,其次为三江平原和松嫩平原地区,大兴安岭地区最少。暴雨发生站次呈明显升高趋势,每10年增加2.3站次,20世纪70年代暴雨发生站次最少,2010年以后最多。最大日降雨量基本上从西南向东北部递减,西南部地区绝大部分地区最大日降雨量都在120mm以上,东北部地区都在120mm以下。     

水氮组合模式对双季稻生长和产量的影响

为双季稻栽培提供最优水肥组合模式,通过大田小区试验设置了淹水灌溉和间歇灌溉2种灌溉方式,结合4种施氮水平,研究了不同水肥条件下水稻生长及其产量差异。结果表明,在相同施氮水平下,间歇灌溉水稻植株干物质积累量明显大于淹水灌溉;不同水肥组合下水稻干物质在植株各器官中的分配表现从大到小为籽粒、茎、叶和根;水稻生育后期叶面积指数以间歇灌溉施中氮最高,茎基伤流量以施中氮最高,相同施氮条件下间歇灌溉高于淹水灌溉;早稻光合速率差异不显著,相同施氮水平下间歇灌溉略高于淹水灌溉,水分利用率存在显著差异,以间歇灌溉施中氮最高;晚稻不同处理的光合速率、水分利用率存在显著差异,相同施氮水平下间歇灌溉高于淹水灌溉,以间歇灌溉施中氮最高;早稻产量以淹水灌溉施高氮最高,比间歇灌溉不施氮高出46.0%,差异显著,但比其他施氮处理增幅仅为0.3%~7.1%,差异不显著;晚稻产量处理间差异显著,间歇灌溉高于淹水灌溉,以间歇灌溉施中氮最高,比间歇灌溉不施氮高出49.3%,比其他施氮处理增幅为1.7%~8.6%,差异显著。因此,早稻在雨水充足的前提下淹水灌溉施高氮可获得高产,晚稻以间歇灌溉施中氮为宜。     

Influence of Soil Moisture on Growth, Water Use and Yield of Mustard

A field experiment was conducted to study the influence of soil moisture on growth, water use and yield of mustard ( Brassica juncea L. cv. Rai 5 ). Two soil moisture regimes were rainfed and irrigated at 10 days interval throughout the growing season. The total amount of water received as irrigation was 110 mm and as rainfall was 15 mm. Total dry matter per unit ground area, leaf area index (LAI), crop growth rate (CGR) and net assimilation rate (NAR) were increased and leaf area ratio (LAR) and specific leaf area (SLA) were decreased by irrigation. Chlorophyll content and relative leaf water content (RLWC) were increased by irrigation, but proline content was greater in the rainfed crop at both the flowering and pod-filling stages. Time taken to first flowering, duration of flowering, number of seeds/pod and harvest index were unaffected by irrigation. Plant height at harvest, number of pods/plant, seed yield and oil content of seeds were increased and 1000-seed weight was decreased by irrigation. The consumptive use of water increased with an increase in water supply, but the water use efficiency (WUE) was decreased.     

高产小麦耗水特性及干物质的积累与分配

在2005—2006年和2006—2007年小麦生长季降水量分别为128.0 mm和246.4 mm条件下, 采用不同灌水量处理, 研究了高产条件下冬小麦的耗水特性和小麦干物质的积累与分配。结果表明, 底水和拔节水分别灌溉60 mm处理(W2)在两个生长季获得了最高的籽粒产量, 2005—2006年生长季其水分利用效率和灌溉水的利用效率均显著高于其他灌水处理; 2006—2007年生长季, 其水分利用效率较高, 降水量、灌水量和土壤供水量分别占农田耗水量的47.32%、23.04%和29.64%; 与不灌水处理(W0)相比, 灌水处理显著提高开花后干物质的积累量和开花后干物质积累量对籽粒的贡献率, 以W2处理最高, 分别达8 241.59 kg hm-2和84.18%。灌水量过多显著减少光合产物向籽粒的分配, 使产量降低。随灌水量增加, 小麦全生育期耗水量显著增大, 灌水量占农田耗水量的比例增加, 降水量和土壤供水量占农田耗水量的比例均降低, 以土壤供水量所占比例降低最大。综合考虑小麦的籽粒产量和水分利用效率, 在本试验条件下, 以底水和拔节水各60 mm的灌溉量为最优。在小麦生长季降雨量为246.4 mm条件下, 仅灌60 mm底水亦可获得较高的籽粒产量, 其土壤供水量占农田耗水量的比例和灌溉水的利用效率高于底水和拔节水处理。     

Water use by soybean in two soils with and without irrigation

Water use and seed yield of soybeans (Glycine max. L.), grown on two soils with and without irrigation were investigated. Seed yield, in each soil type, was significantly correlated to water use. Most of the differences in water use, between the irregated versus dryland treatments, in each soil type, occurred during the podfill growth stage. The podfill growth stage water use, in the irrigated treatment of each soil type, was almost twice that in the corresponding dryland. The podfill growth stage water use, irrespective of the treatments, varied with the soil type. This was attributed to the differences in the contribution of preplant profile stored water between the soil types. The contribution of preplant profile storage, in one soil type, to podfill growth stage water use was similar to the rainfall received during this growth stage in this soil type. However, in the second soil type the corresponding contribution was almost three times that of the rainfall. The results indicated soybean seed yield benefitted most from irrigation during the podfill growth stage. The results suggests the information in preplant profile storage, availability and use, in conjunction with rainfall is useful in developing appropriate soil water management practices.