蓄水坑灌土壤水分分布特征研究

为了揭示蓄水坑灌条件下土壤水分分布特征,提高蓄水坑灌水分利用效率,本文利用TRIME-PICO IPH土壤水分测量系统,进行了蓄水坑灌与普通地面灌溉条件下果园土壤含水率分布对比试验,分析了不同灌溉方法下土壤含水率随垂向、径向的变化。结果表明：蓄水坑灌条件下,土壤水分主要分布在垂向40-160cm内,土壤含水率增量随深度呈先增大后减小的趋势,含水率增量最大值出现在坑底附近,且距离蓄水坑近处,含水率增量较大,然后沿坑两侧依次递减;地面灌溉条件下,土壤水分主要分布在垂向0-80cm内,土壤含水率增量随深度增大而减小,含水率增量最大值出现在地表,且沿各个径向距离增长幅度较为一致。研究结果将为蓄水坑灌法的田间推广提供科学依据。     

秸秆隔层及不同灌水上限对土壤水氮分布的影响

【目的】探究秸秆隔层以上适宜的灌水上限及其对土壤水分和氮素分布的影响。【方法】通过室内土柱入渗试验,研究了秸秆隔层埋深25cm时饱和含水率、田间持水率、80%田间持水率3个灌水上限情况下土壤水分入渗及水氮分布情况。【结果】①秸秆隔层能抑制水分入渗,显著增加0～25 cm土层的储水量和储水效率。在无蒸发条件下,当灌水上限不超过田间持水率时,6 d后0～25 cm土壤水的储存效率达89%～91%;②秸秆隔层能抑制硝态氮的深层渗漏,增加0～25cm土体硝态氮量。80%田间持水率灌水上限结合秸秆隔层处理对0～25cm土层硝态氮量高于其他处理。【结论】秸秆隔层以上适宜的灌水上限为80%田间持水率。     

浅层土壤水分特征曲线模拟与运移机理研究

土壤水分作为干旱环境下影响植物生长发育生存的关键因子,对植物正常生长起至关重要作用。为此,以不同性质土壤为研究对象,设置了4种类型土柱,研究不同类型土壤下的水分垂直分布变化规律,建立浅层与深层土壤水分含量的定量模型。结果表明:建立表层土壤与深层土壤的4种土壤含水率的回归模型,90cm土层深度的土壤含水率为田间持水率80%的二次曲线拟合的效果最好;低浓度盐水(0.2%)建立的浅层与深层土壤水分含量反演模型效果更优,为我国土壤水分监测研究提供了借鉴。     

蓄水坑灌不同坑深条件下土壤水分分布特征分析

蓄水坑灌是一种新型的果林节水灌溉方法,为了给合理确定蓄水坑坑深提供依据,在田间进行了不同坑深条件下蓄水坑灌土壤水分运动试验。试验设置2种不同蓄水坑深40cm和60cm,并对灌前和灌后土壤含水率增量在垂向和径向的分布特征进行分析研究。结果表明,在不同蓄水坑深40,60cm条件下,土壤含水率增量在垂向上的变化趋势一致,均是随着深度的增加,呈现先增大后减少的趋势,但随着坑深增大,土壤含水率增量的高值区的范围也越深;不同坑深条件下的土壤含水率增量在径向上的分布无明显的差异,均呈现以蓄水坑为中心,在蓄水坑附近的土壤含水率增量较大,距蓄水坑较远的地方,土壤含水率增量较低。通过对不同坑深条件下蓄水坑灌土壤水分运动的研究,可以为实际应用中,根据不同果树根系的水分吸收环境来选择坑深奠定理论依据。     

水钾耦合对北疆机采棉水钾利用效率及产量的影响

【目的】探索不同土壤含水率区间与钾肥施用量之间的耦合效应,优化机采棉灌水和钾肥施用方案。【方法】以膜下滴灌棉花为研究对象,设计了3个土壤含水率(田间持水率的40%～60%、60%～80%和80%～100%,W1、W2、W3)和3个施钾水平(30、60和90 kg/hm~2,K1、K2、K3),研究了机采棉的株高、叶面积指数、生物量和产量。【结果】土壤含水率为田间持水率的60%～80%时,钾肥对棉花株高的增益效果更加明显;施钾量在30 kg/hm~2和60 kg/hm~2时,土壤含水率能显著提高株高的日增长量。叶面积指数随着施钾量和灌水量的增加而增加。土壤含水率为田间持水率的60%～80%且施钾量为90 kg/hm~2时,最有利于棉花生物量的形成。土壤含水率为田间持水率的60%～80%时,棉花单株有效铃数和籽棉产量最多,且籽棉产量和有效铃数随着施钾量的增加而增加,W2K3处理的籽棉产量最高(7 579.78 kg/hm~2),有效铃数最高(9.03个/株)。钾肥能促进棉花单铃质量的形成,但是单株有效铃数的增加会减缓钾肥对棉花单铃质量的促进作用。当灌水水平一致时,钾肥生产效率随着施钾量的增加而显著降低。在土壤含水率为田间持水率的80%～100%且施钾量为90 kg/hm~2时,棉花的水分利用效率最低。【结论】土壤含水率为田间持水率的60%～80%且施钾量为90 kg/hm~2为适宜的灌水施肥方案,有利于生物量向生殖生长倾斜,获得较高的水钾利用效率以及棉花籽棉产量。     

围垦年限和土壤容重对海涂土壤水分运动参数的影响

为探讨围垦年限和土壤容重双因素对海涂土壤水分运动参数的影响,在室内试验的基础上结合理论计算,对海涂4个年限围垦区土壤2个不同容重下土壤导水率、水分特征曲线和扩散率的变化进行了研究。结果表明:围垦年限对土壤颗粒组成、结构及钠盐含量等影响显著,土壤饱和导水率随围垦年限的增长而减小;持水能力、土壤水分扩散率随围垦年限的增长而增大。土壤饱和导水率、吸渗率、土壤水分扩散率及相同土壤吸力下的含水率均随容重的增大而减小,随着围垦年限的增长,土壤容重对水分运动参数的影响更明显。     

时域反射仪对水分非均匀分布土壤含水率的测定

为了评估时域反射仪测定水分非均匀分布土壤的含水率的性能，该研究在室内试验中将土柱纵向分为上下2层，设置土壤水分差为0.05、0.10和0.15 cm3/cm3 3种情况，进行不同含水率梯度下水分非均匀分布对该仪器测定土壤含水率的影响试验，并在田间试验中进行了实地测试。结果表明，在室内新型时域反射仪随着上下2层土壤含水率梯度差的增加，测定土壤含水率的均方根误差略有增大，在水分分布相对均匀的土壤中测定土壤含水率的均方根误差小于 0.028 cm3/cm3。在田间竖直埋设探头，上湿下干和上干下湿的土壤     

土壤水分调控对超级稻根系特征的影响

【目的】探究土壤中不同含水率对超级稻节水率以及节水条件下根系生长特征的影响。【方法】采用盆栽试验,通过设置不同的土壤含水率,以占田间持水率比例进行划分:A处理(90%~100%)、B处理(80%~90%)、C处理(70%~80%)、D处理(60%~70%),并以充分灌溉为对照(CK),测算了超级稻全生育期灌溉耗水量,并测试了超级稻不同生长阶段根系相关特征指标。【结果】土壤水分调控处理比CK节水15%~30%。土壤水分调控处理能够增加超级稻根系平均直径24.67%、总根体积4.80%。在超级稻生长阶段的颖花结实期和成熟期,土壤水分调控处理组根系活力高于CK。B处理根系生长优于其他土壤水分调控处理,另外B处理超级稻平均根系干物质积累量为92.36 g。【结论】土壤水分调控处理能减少超级稻灌溉水量,促进根系发育,提高耐旱性;土壤水分为田间持水率的80%~90%时,超级稻根系生长最佳。     

玉米光合指标与土壤水分的关系研究

在防雨棚内膜下滴灌条件下,通过小区试验研究玉米拔节期和抽雄期光合指标(蒸腾速率、光合速率、气孔导度)与土壤水分的关系。结果表明,在玉米拔节期,当土壤水分达到田间持水率的70%时,玉米光合强度最强;光合指标与土壤水分的典型相关系数为0.919,其相关性极显著(P0.01),在光合要素中,蒸腾速率的权重最大。在玉米抽雄期,当土壤水分达到田间持水率的85%时,玉米光合强度最强;且各光合指标均高于拔节期,此时其典型相关系数为0.742,相关性极显著,在光合要素中,则变为光合速率的权重最大,成为主要被影响因素。结合各时期产量,可以确定玉米在拔节期和抽雄期的最适宜土壤含水率分别为田间持水率的70%和田间持水率的85%。     

水稻控制灌溉下华东稻麦轮作农田N2O排放模拟

基于田间小区试验,利用DNDC模型模拟了水稻控制灌溉下的华东稻麦轮作农田N_2O排放情况,分析了DNDC模型在该地区以及水稻控制灌溉条件下的适用性。结果表明,DNDC模型能较好地模拟控制灌溉稻田N_2O排放规律,模拟值与实测值的相关系数为0.79(n=39,p0.001);同时能较好地模拟控制灌溉稻田N_2O排放通量与土壤水分调控及施肥的关系。但模型对土壤脱水程度的响应不够敏感,导致部分峰值出现时间稍有滞后。后茬麦田N_2O排放通量的模拟值多低于实测,模拟主峰值较实测值增大了14.96%(p0.05),模拟次峰值比实测值减小了18.10%(p0.05)。稻季、麦季及稻麦轮作期的N_2O排放总量的模拟值与实测值的相对误差分别为5.86%、-20.17%(p0.05)和-4.97%,可见,DNDC模型能较好地模拟控制灌溉稻田N_2O排放总量,但明显低估了后茬冬小麦田的N_2O排放总量,稻麦轮作农田N_2O排放总量的模拟值和实测值总量相差不大。因此,DNDC模型可以用来模拟华东地区控制灌溉稻田N_2O排放,但不能准确地模拟后茬冬小麦田的N_2O排放。     

Overland water and salt flows in a set of rice paddies

Cultivation of paddy rice in semiarid areas of the world faces problems related to water scarcity. This paper aims at characterizing water use in a set of paddies located in the central Ebro basin of Spain using experimentation and computer simulation. A commercial field with six interconnected paddies, with a total area of 5.31 ha, was instrumented to measure discharge and water quality at the inflow and at the runoff outlet. The soil was classified as a Typic Calcixerept, and was characterized by a mild salinity (2.5 dS m⁻¹) and an infiltration rate of 5.8 mm day⁻¹. The evolution of flow depth at all paddies was recorded. Data from the 2002 rice-growing season was elaborated using a mass balance approach to estimate the infiltration rate and the evolution of discharge between paddies. Seasonal crop evapotranspiration, estimated with the surface renewal method, was 731 mm (5.1 mm day⁻¹), very similar to that of other summer cereals grown in the area, like corn. The irrigation input was 1874 mm, deep percolation was 830 mm and surface runoff was 372 mm. Irrigation efficiency was estimated as 41%. The quality of surface runoff water was slightly degraded due to evapoconcentration and to the contact with the soil. During the period 2001–2003, the electrical conductivity of surface runoff water was 54% higher than that of irrigation water. However, the runoff water was suitable for irrigation. A mechanistic mass balance model of inter-paddy water flow permitted to conclude that improvements in irrigation efficiency cannot be easily obtained in the experimental conditions. Since deep percolation losses more than double surface runoff losses, a reduction in irrigation discharge would not have much room for efficiency improvement. Simulations also showed that rice irrigation performance was not negatively affected by the fluctuating inflow hydrograph. These hydrographs are typical of turnouts located at the tail end of tertiary irrigation ditches. In fact, these are the sites where rice has been historically cultivated in the study area, since local soils are often saline-sodic and can only grow paddy rice taking advantage of the low salinity of the irrigation water. The low infiltration rate characteristic of these saline-sodic soils (an experimental value of 3.2 mm day⁻¹ was obtained) combined with a reduced irrigation discharge resulted in a simulated irrigation efficiency of 60%. Paddy rice irrigation efficiency can attain reasonable values in the local saline-sodic soils, where the infiltration rate is clearly smaller than the average daily rice evapotranspiration.     

瓦房店市水果生产标准化发展研究

瓦房店市是我国重要的水果生产基地,在国内水果生产领域占有重要地位。随着水果市场化的不断深入,如何满足和适应国内外市场需求成为瓦房店市水果生产的关键问题。从瓦房店市水果生产实际出发,阐述了实施水果生产标准化的必要性,提出了发展水果生产标准化的具体措施。     

金谷子耐旱TG118引种试种及推广应用

对引进的谷子新品种金谷子耐旱TG118进行品种比较试验和多点试种。结果表明：该品种抗旱、耐瘠、适应性强,稳产、高产、抗病抗风抗倒伏强,品质优良,粮草兼用,种植简单,省工易管;一般产量在6000kg/hm2以上,比当地主栽品种增产20%以上。最高产量达9450kg/hm2,适于在辽西北地区推广应用。     

对《种子法》存在问题的探讨

《种子法》是我国种植业第一部法律。自实施以来,为依法加强种子管理提供了有力的法律支撑,促进我国种子产业发生翻天覆地的变化。但随着依法管理工作的深入和种子产业的快速发展,《种子法》及配套规章的一些问题逐步显现出来。对《种子法》及配套规章存在的问题进行深入分析,对需要进一步补充的章节以及需要调整的内容进行深入探讨,以求更加完善和明确。     

Review of the Egyptian experience in implementing land drainage projects

About 30 years have passed since the Government of Egypt embarked on implementing a series of large scale drainage projects. At present, about 3.8 million acres have been provided with drainage systems on the basis of systematic pre-drainage investigations and designs. The target is to provide drains in approximately 6.4 million acres in the Nile Valley and Delta.The implementation of the subsurface drainage system is carried out by the public sector and private contractors under direct supervision of governmental regional departments. The implementation process depends on many factors related to the drainage material, machinery, manpower, site requirements, farmers and organizations involved. Problems and constraints are sometimes challenging, however, the annual rate of implementation has gradually increased to 170,000 acre/year.This paper discusses the different aspects involved in the implementation process of drainage systems. The development in materials, machinery and construction technologies will be reviewed. Institutional and management factors are going to be also considered.     

和谐社会理论建设的几点哲学思考

在新世纪,面对机遇和挑战,党的十六大把“社会更加和谐”作为全面建设更高水平的小康社会的一个重要目标。中国人素有社会和谐的理想;西方人自古也向往社会和谐;借鉴东西方两种和谐社会思想的经验、教训,构建社会主义和谐社会理论。     

A European irrigation map for spatially distributed agricultural modelling

We present a pan-European irrigation map based on regional European statistics, a European land use map and a global irrigation map. The map provides spatial information on the distribution of irrigated areas per crop type which allows determining irrigated areas at the level of spatial modelling units. The map is a requirement for a European scale assessment of the impacts of irrigated agriculture on water resources based on spatially distributed modelling of crop growth and water balance. The irrigation map was compiled in a two step procedure. First, irrigated areas were distributed to potentially irrigated crops at a regional level (European statistical regions NUTS3), combining Farm Structure Survey (FSS) data on irrigated area, crop-specific irrigated area for crops whenever available, and total crop area. Second, crop-specific irrigated area was distributed within each statistical region based on the crop distribution given in our land use map. A global map of irrigated areas with a 5′ resolution was used to further constrain the distribution within each NUTS3 based on the density of irrigated areas. The constrained distribution of irrigated areas as taken from statistics to a high resolution dataset enables us to estimate irrigated areas for various spatial entities, including administrative, natural and artificial units, providing a reasonable input scenario for large-scale distributed modelling applications. The dataset bridges a gap between global datasets and detailed regional data on the distribution of irrigated areas and provides information for various assessments and modelling applications.     

粉质仪和拉伸仪在面粉生产中的应用

在介绍粉质仪和拉伸仪结构和原理的基础上,探讨了粉质曲线中吸水率、形成时间、稳定时间、弱化度和评价值等指标与面粉品质的关系,以及如何根据拉伸曲线中面团最大拉伸阻力、延伸度和拉伸曲线面积等指标来评价面团品质,并结合生产实际,概述了粉质仪和拉伸仪在面粉生产中的作用。     

农村信息化服务的现状及建设措施

分析当前我国农村信息化服务的现状,提出加强农村信息化服务的新举措。     

车辆ABS控制算法的研究及探讨

对现代汽车的ABS控制算法作了一些简单的介绍,同时指出了它们的一些缺陷,相应地提出了几种对ABS的其它控制方法并加以探讨,其中着重论述了ABS门限值控制算法中参考车速的确定方法和基于附着系数的控制算法。