基于土壤湿度参数的自动化节水灌溉装置在草坪绿地上的应用

草坪建植和养护需要消耗大量水资源，而我国人均淡水量仅有2 240 m3，是世界平均淡水拥有水平的1/4，因此，草坪业在我国发展缓慢，群众接受度较低。基于土壤湿度参数的绿地草坪自动化节水灌溉装置由控制器、传感器、电磁阀及中央控制器构成，理论核心是草坪调亏灌溉理论。装置通过在草坪土层中安装测定土壤持水量的传感器，采集土壤湿度信息，将数据反馈给控制终端，控制终端结合草坪草的性质及传感器反馈的信息，确定出该草坪所处的水分需求状态，从而通过控制电磁阀开闭来控制灌溉量，对灌溉进行有效调控。该装置具备数据采集、灌溉控制、参数设置和数据处理等功能，可以精准控制土壤湿度，减少草坪耗水量、提高水分利用率，并设置适当水分胁迫，使草坪在更低的耗水量下长势更优。该文论述了装置的组成及运行原理，并结合市场现有灌溉装置进行对比与分析。结果表明，该装置实现了对草坪需水程度的实时监测与智能调控，减少无效灌溉，提升灌溉效率，可以发展出以减少灌溉定额、提升草坪质量为目的的新型灌溉模式，降低草坪养护成本。      

水稻根茬-土壤复合体剪切特性试验

为了降低稻茬地少耕免耕过程中的阻力,提高作业质量,同时为破茬开沟装置提供设计依据,采用自制的剪切试验装置在万能材料试验机上对水稻根茬-土壤复合体进行了剪切试验,对根茬-土壤复合体含水率、土壤容重、根茬-土壤复合体的当量直径、剪切位置、剪切速度、切刃刃角、切刀刃口形状7个因素进行了单因素试验。在单因素试验的基础上选取根茬-土壤复合体含水率、剪切速度、切刃刃角3个因素进行了正交试验。单因素试验结果显示:极限剪切应力与复合体的含水率呈二次多项式函数关系,与土壤容重呈幂函数关系,与根茬-土壤复合体直径呈二次多项式函数关系,与剪切速度呈对数函数关系,剪切位置距离根茬中心越远极限剪应力越小,切刃刃角越小极限剪切应力也越小;在4种形状的刃口切刀中,凹圆弧切刃的极限剪切应力最小。正交试验结果表明:切割速度450 mm/min、含水率25%、切刃刃角15°时,极限剪切应力最小。     

Yield and nitrogen balance of broccoli at different soil moisture levels

The effect of watering up to approximately 100% of volumetric available soil water on total biomass, nitrogen (N) balance, and market yield of broccoli crops (Brassica oleracea L. convar. botrytis var. italica Plenck, cv. Emperor) was studied. The experiment was carried out in a microplot field installation on two soil types (alluvial loam and loessal loam) under spring and autumn cultivation and consisted of three soil water regimes: plants received 21 mm of water by irrigation until the soil moisture reached 75% of the available soil water (ASW), treatment 1; 42 mm after the soil moisture reached 55% ASW, treatment 2; and 63 mm after the soil moisture reached 35% ASW, treatment 3. The ASW of the three treatments was measured at a depth of 0.15 m. The total plant mass was significantly affected by the irrigation strategy on the loessal loam in spring and on the alluvial loam in autumn. The total mass and head mass were lowest when water was applied at 75% ASW in spring and autumn. Calculations of N-balances showed that N losses were large, i.e. more than 70 kg·ha^–1 in spring and 130 kg·ha^–1 in autumn on the alluvial loam in treatment 1, and were only slightly affected by the irrigation strategy on the loessal loam.Communicated by R. Evans     

Evaluation of capacitance probes for optimal irrigation of citrus through soil moisture monitoring in an entisol profile

 Continuous monitoring of soil moisture content within and below the rooting zone can facilitate optimal irrigation scheduling aimed at minimizing both the effects of water stress on the plants, and also the leaching of water below the root zone, which can have adverse environmental effects. The use of Sentek capacitance probes (EnviroSCAN RT5) in scheduling citrus irrigation was evaluated using 3-year-old Hamlin orange trees [Citrus sinensis (L.) Osb.] on Swingle citrumelo rootstock [Citrus paradisi Macf. × Poncirus trifoliata (L.) Raf.] grown in a Candler fine sand (hyperthermic, uncoated, Typic Quartzipsamments). Available soil moisture calculated according to capacitance probe readings of soil moisture agreed well with that calculated using soil water release curves determined in the laboratory. A utility program was developed to process the data collected by the capacitance probe into a spreadsheet format. Processed data were used to calculate soil water storage within and below the citrus root zone at desired time intervals. Irrigation set points (i.e., full point equivalent to maximum desirable water storage and refill points I and II) were defined based on field capacity determined both in the field and in the laboratory and permanent wilting point. It was possible to maintain the water content in the root zone between the full and refill points I and II during most of the growing season. Although soil water content in the root zone exceeded the full point during periods of high irrigation, it drained rapidly within 24–48 h after the end of such irrigation events. Using soil moisture depletion in the root zone during periods of low water application to estimate citrus evapotranspiration (ET), the calculated daily average ET during 10-day period in November was 1.33 mm day⁻¹. Received: 11 August 1998     

Effect of soil moisture regimes on the yield and water use of lentil (Lens culinaris Medic)

Summary The effect of soil moisture regimes on the grain and straw yield, consumptive water use (Cu) and its relation with evaporation from free water surface (Eo), water use efficiency and soil moisture extraction pattern of lentil was studied in a field experiment conducted at the Indian Agricultural Research Institute, New Delhi during the fall-spring season of the crop years 1979–1980 and 1980–1981. The grain and straw yield, consumptive water use rate, Cu/Eo ratio and water use efficiency increased with an increase in irrigation frequency. Consumptive water use rate increased as the crop season advanced and reached its peak value during flowering and grain filling stage. The Cu/Eo ratio attained its minimum values 35 and 105 days after sowing at branching and grain filling stages. Depletion of soil moisture was most from the top 0–30 cm soil layer followed by 30–60 cm soil layer and was least from 90–120 cm soil layer. The pattern of soil moisture depletion was also influenced by soil moisture regime. During the vegetative and flowering stage the percent contribution from the top 0–30 cm soil layer decreased and that from the lower soil layers (30–60, 60–90, and 90–120 cm) increased with an increase in the soil moisture tension, however, the actual amount of moisture depleted from all the soil layers was always higher under low soil moisture tension regime than under high soil moisture tension regime. During the grain development stage the soil moisture treatment had no significant effect on the relative contribution from different soil layers under low and high soil moisture tension as the crop was irrigated at the same time under both these treatments. However, with no irrigation, the percent contribution from top soil layer continued to decrease, and from lower soil layers continued to increase, as the crop advanced from flowering stage to grain development stage.     

Canopy temperature as a measure of salinity stress on sorghum

Summary A complete understanding of plant response to combined water and salinity stress is desirable. Previous growth chamber and greenhouse experiments with sorghum and maize indicate that soil salinity, by negatively affecting growth processes, may reduce consumptive water use, thus prolonging the supply of available soil moisture. In the present field experiment, canopy temperature measurements were used to examine the effect of soil salinity on the plant-soil water relations of sorghum (Sorghum bicolor L. cv. Northrup King 1580). An infrared thermometer was used to measure canopy temperature during a 9-day period including two irrigations in plots of various salinities. The salinity treatments were created by a dual line-source sprinkler irrigation system, which applied waters of different quality. Excess irrigation allowed soil moisture to be uniform across the salinity treatments at the beginning of the measurement period. Consumptive water use and soil salinity were measured to quantify the salinity and water treatments. Grain and dry matter yields provided measures of plant response. Canopy temperature measurements were sensitive enough to detect differences across the salinity treatments when soil moisture was uniform for several days following irrigation. However, over the 9-day measurement period, plants in the low-salt plots used more water than plants in the high-salt plots. This differential water use eventually offset the salinity-induced stress, with the result that temperature differences were eliminated. Differences in temperature were observed again following irrigation. The results demonstrate that canopy temperature can be used as a tool to detect salinity stress on sorghum. Timing of measurements with regard to irrigation is identified as a key factor in detecting temperature differences that can be attributed to the presence of soil salinity.     

加筋率和含水率对木纤维红黏土边坡稳定性的影响

为了研究木纤维在不同含水率下对红黏土边坡稳定性的影响,采用直剪试验和边坡稳定性模拟分析方法,对加筋率为0（素土）、0.5%、2.5%和5.0%共4个处理在5个不同含水率水平下的木纤维加筋红黏土试样测定土体黏聚力和内摩擦角,分析边坡土体的最小安全系数。结果表明:加筋率越高,土体内摩擦角越小,黏聚力越大,木纤维主要以提高黏聚力来增强土体稳定性;木纤维红黏土在含水率＜25%时,木纤维能增强抗剪强度,提高边坡最小安全系数,且加筋率越高,抗剪强度和最小安全系数越大,边坡稳定性越好。      

Effects of irrigation regimes on the yield and water use of strawberry

Summary Strawberry plants (Fragaria x annanasa D. cv Chandler) were grown in field plots and in drainage lysimeters under controlled soil moisture regimes. Four irrigation treatments were established by watering the plants when soil water potential reached -0.01, -0.03,-0.05 and -0.07 MPa. The maximum yield was attained at -0.01 MPa soil water potential. Differences in yield were caused by both changes in the number of fruits per plant and in the fresh weight per fruit. Yield reductions were associated with reductions in total assimilation rate resulting from the decreased assimilatory surface area in plants irrigated at lower soil water potentials. The crop water production function calculated on a fruit fresh weight basis resulted in a yield response factor (K _y) of 1.01.     

油菜直播地表土壤物理机械特性参数测量装置研究

针对油菜直播地表农田土壤物理机械特性参数室内测量费时费力、田间测量仪器功能单一等问题,设计了一种油菜直播地表土壤物理机械特性参数测量装置,实现集成测量土壤含水率、坚实度、粘聚力和内摩擦角4种土壤物理机械特性参数且测量结果可以通过手机APP实时储存显示。装置基于自走式移动平台实现行走控制,以STM32单片机为核心控制器,利用FDR传感器获取土壤含水率,通过圆锥贯入部件测量土壤坚实度和抗剪切强度参数(包括粘聚力和内摩擦角)。分析了装置的圆锥贯入部件和土壤含水率检测部件测量原理,设计了装置测量控制系统硬件电路及软件,开展了传感器标定试验,确定了柱式压力传感器、薄膜压力传感器和土壤水分传感器的输入输出响应关系。选取71个土壤样本,融合土壤含水率和基于圆锥受力平衡关系获取的摩擦因数,运用最小二乘法建立了土壤粘聚力和内摩擦角数学测量模型,模型决定系数R²分别为0.932和0.956。开展了装置田间测量试验,对土壤含水率、坚实度、粘聚力和内摩擦角进行集成测量,结果表明：相较于AYD-2型土壤坚实度仪、干燥箱干燥法和ZJ-D型直剪仪测量结果,油菜直播地表土壤物理机械特性参数测量装...     

双针结构土壤水分传感器探针最优长度分析与试验

在两针平行式探针结构的阻抗模型的基础上,进一步理论推导了终端开路式和终端短路式两种类型土壤水分传感器探针长度与阻抗特性的关系.借助高频分析软件HFSS确定了两针平行式土壤水分传感器的最佳探针结构,并采用有机溶液模拟土壤体积含水率进行了试验,试验结果表明:终端开路式和终端短路式土壤水分传感器探针长度在0 ～8.3 cm时,其土壤体积含水率测量范围达到0～100％.     

Effect of irrigation methods,management and salinity of irrigation water on tomato yield,soil moisture and salinity distribution

The increasing demand for irrigation water to secure food for growing populations with limited water supply suggests re-thinking the use of non-conventional water resources. The latter includes saline drainage water, brackish groundwater and treated waste water. The effects of using saline drainage water (electrical conductivity of 4.2–4.8 dS m⁻¹) to irrigate field-grown tomato (Lycopersicon esculentum Mill cv Floradade) using drip and furrow irrigation systems were evaluated, together with the distribution of soil moisture and salt. The saline water was either diluted to different salinity levels using fresh water (blended) or used cyclically with fresh water. The results of two seasons of study (2001 and 2002) showed that increasing salinity resulted in decreased leaf area index, plant dry weight, fruit total yield and individual fruit weight. In all cases, the growth parameters and yield as well as the water use efficiency were greater for drip irrigated tomato plants than furrow-irrigated plants. However, furrow irrigation produced higher individual fruit weight. The electrical conductivity of the soil solution (extracted 48 h after irrigation) showed greater fluctuations when cyclic water management was used compared to those plots irrigated with blended water. In both drip and furrow irrigation, measurements of soil moisture one day after irrigation, showed that soil moisture was higher at the top 20 cm layer and at the location of the irrigation water source; soil moisture was at a minimum in the root zone (20–40 cm layer), but showed a gradual increase at 40–60 and 60–90 cm and was stable at 90–120 cm depth. Soil water content decreased gradually as the distance from the irrigation water source increased. In addition, a few days after irrigation, the soil moisture content decreased, but the deficit was most pronounced in the surface layer. Soil salinity at the irrigation source was lower at a depth of 15 cm (surface layer) than that at 30 and 60 cm, and was minimal in deeper layers (i.e. 90 cm). Salinity increased as the distance from the irrigation source increased particularly in the surface layer. The results indicated that the salinity followed the water front. We concluded that the careful and efficient management of irrigation with saline water can leave the groundwater salinity levels unaffected and recommended the use of drip irrigation as the fruit yield per unit of water used was on average one-third higher than when using furrow irrigation.     

不同含水量下工具材料切向土壤黏附特性（摘选）

为了提高越野车辆性能和建筑、农业领域机械工作效率,就需要了解土壤黏附机理。该试验旨在找到不同工具材料的土壤切向黏附与含水率之间的关系,探讨土壤切向黏附对土壤剪切力学性能的影响。试验对橡胶（RUB）、钢（SS400）和树脂（PEEK）3种材料进行了直剪试验。结果表明,土壤和材料之间的切向黏附随着土壤含水量的增加而增加至最大值后降低。土壤切向黏附最大值的排序是钢（SS400）,其次是橡胶（RUB）,最后是树脂（PEEK）。结果还表明,3种材料道具与测试土壤间的外摩擦角随着土壤含水率的增加先降低后增加,当发生剪切的时候,随着剪切的发生,土壤含水量导致切向黏附的变化进而直接影响剪切应力和外摩擦角。      

Cotton root and shoot responses to subsurface drip irrigation and partial wetting of the upper soil profile

The ability of cotton roots to grow downwards through a partially-wetted soil (Calcic Haploxeralf) profile toward a water source located beneath them was investigated. Plants were grown in 60-cm-high soil columms (diameter 10 cm), the bottom 15 cm of which was kept wet by frequent drip irrigation, while the upper 45 cm was wetted three times per week up to 20, 40, 60, 80 or 100% of pot capacity. Pot capacity was defined as the water content which gave uniform distribution within the pot and was at a soil matric potential ( _m ) of –0.01 MPa. Plants were harvested 42 and 70 days after emergence (DAE). Root length density was reduced by decreased soil moisture content. At 42 DAE, density was reduced in the soil profile down to 36 cm. The density in the middle segment of the cylinder (24–36 cm) increased at the second harvest, from 0.1 to 0.35 cm · cm^–3 at 40% and from 0.2 to 0.5 cm · cm^–1 at 60% of pot capacity, respectively. A significant rise in root length density was found at all moisture contents above 20% in the two deepest soil segments. It was most marked at 40% where the rise was from 0.2 to 0.8 cm · cm^–3, due to the development of secondary roots at the wetted bottom of the column. When only 20% of pot capacity was maintained in the top 45 cm of the profile, almost no roots reached the wetted soil volume, and root length density was very low. Hydrotropism, namely root growth through dry soil layers toward a wet soil layer was thus not apparent. Root dry weight per unit length decreased with increasing depth in the column at all moisture levels. However, the only significant decrease was, found between the top and the second soil segments and was due to thicker primary roots in the top segment. There was no clear relationship between length and dry weight of roots. Total plant dry weight and transpiration were reduced significantly only at 20% of pot capacity. Dry matter production by roots was less severely inhibited than that by shoots, under decreased moisture content in the soil profile. Leaf water potential decreased when the soil moisture content of the top 45 cm of the profile was reduced below 60% of pot capacity. It was concluded that even at soil moisture content equivalent to a _m of 0.1 MPa, the rate of root growth was sufficient to reach a wetted soil layer at the bottom of the soil column, where the plant roots then proliferated. This implies that as long as the soil above the subsurface dripper is not very dry there is no real need for early surface irrigation.     

淮北平原汉王实验站土壤水资源特征试验研究

为了充分认识土壤水及其水资源特性,在淮北平原汉王水文水资源实验站对0.5～3.5 m地下水位控制条件下和秸秆、地膜、无覆盖三种条件下的土壤水分、包气带储水量、潜水蒸发、土壤蒸发、降雨入渗等要素进行了连续4年的观测,并结合水量平衡方程,对土壤水资源的要素特征进行了实验研究.结果表明：同一深度的土壤含水量大小顺序为秸秆覆盖〉地膜覆盖〉无覆盖;覆盖条件下土壤含水量变化相对稳定;土壤包气带有类似于土壤水库的作用,可调节水量可观,土壤水可作为一种重要的水资源;随土壤包气带厚度加大,潜水蒸发和降水下渗逐步减少,土壤蒸发表现突出.研究认为,充分认识土壤水资源特征,对指导土壤水资源开发利用、农业生产等有重要意义.     

Investigating water availability for introducing an additional crop yield in dry season on hill land at Rubirizi, Rwanda

The study explores the potential of introducing an additional crop during dry season in Rwanda, comparing the efficiency of in situ soil moisture conservation techniques to sustain rain-fed agriculture. Comparative study of in situ soil moisture conservation techniques in bench terraces and unterraced field with maize crop had been conducted from June 2007 to October 2007. Bench terrace increased the average soil moisture content in 90 cm soil depth by more than 50% than that of unterraced land. Within the bench terraced field compartment bund and ridges and furrows increased soil moisture by 19.5% and 27.9% higher than plain bed. In terms of efficiency of moisture conservation, ridges and furrows performed well with 85.8% followed by compartment bund with 75.9% in terraced field. Unterraced field conserved moisture very poorly with 13.9% efficiency inferring importance of bench terraces for soil moisture conservation. No maize grain yield was recorded in all the techniques because soil water depleted to 60% and above from the beginning of the cropping period inferring the need of supplementary irrigation. Analysis of rainfall, crop water demand and in situ moisture conservation reveals exciting opportunities for water productivity enhancements by integrating components of water management within the context of rain-fed farming through water harvesting and supplemental or microirrigation for dry spell mitigation. Detailed analysis is needed for feasibility of lift irrigation with different crops under different altitudes to derive suitable policy for hill land irrigation.     

免耕播种机镇压力精准调控研究

针对目前玉米免耕播种机镇压效果差、镇压强度施加不精准的问题,设计一种免耕播种机镇压力精准调节装置。该装置主要由柔性传力装置、镇压强度调节机构和镇压轮组成。对柔性传力装置进行力学分析,确定柔性传力装置的力学性能;对镇压轮进行受力分析,确定镇压轮工作过程,寻求土壤含水率、橡胶扭转角度、作业速度与土壤紧实度、作业阻力的关系。利用有限元法结合workbench软件对柔性传力装置进行仿真分析,得到扭矩与扭转角度的关系。并进行田间性能试验,采用正交试验考察土壤含水率、橡胶扭转角度、作业速度对镇压装置作业性能的影响,得到各因素的主次顺序为橡胶扭转角度、土壤含水率、作业速度,最优组合为土壤含水率17.093%、作业速度5.655 km/h、橡胶扭转角度15°,此时土壤紧实度为56.8 kPa,作业阻力为109.6 N。试验表明免耕播种机镇压力精准调节装置能够满足农艺要求。     

Can carbon isotope discrimination and ash content predict grain yield and water use efficiency in wheat?

Drought is the main factor affecting crop grain yield. Increasing grain yield under drought and crop water use efficiency (WUE) is essential for enhancing world crop production and food availability. The objective of this study, carried out in India on 20 durum wheat cultivars, under three water regimes (full irrigation, limited irrigation and residual soil moisture) and during two seasons, was to investigate the potential use of plant traits (particularly carbon isotope discrimination, Δ, and ash content, m_a) to predict grain yield and WUE in wheat. WUE components were estimated using a soil water balance model (Budget) allowing comparison of environments in data scarce situations. A highly significant correlation was noted between grain yield and grain Δ across water regimes. However, the associations between grain yield, Δ and m_a were found to depend highly on the water regime and environmental conditions. The association between grain yield and grain Δ was significant under full irrigation in season 1 and under residual soil moisture in season 2. Significant positive correlations were noted in both seasons between grain yield and leaf Δ under residual soil moisture and between grain yield and leaf ash content at anthesis under limited irrigation. A significant correlation was found across environments between grain and leaf Δ and T, the quantity of water transpired during the growth cycle, as estimated by the soil water balance model. T also significantly correlated to grain and leaf m_a. Variation in WUE across environments was driven more by runoff, drainage and soil evaporation than by harvest index and transpiration. The associations between WUE and transpiration, runoff and Δ were negative but not significant. WUE was significantly correlated with leaf and grain m_a at maturity. The study indicates that Δ and m_a can be used as indirect selection criteria for grain yield and suggests that m_a is a good predictor of transpiration, grain yield and WUE across environments. The use of mechanistic models that allows differentiating between cultivars should permit in a next future to analyze the relationships between WUE, Δ and m_a across cultivars and evaluate the possibility to use these traits as predictors of WUE in wheat breeding programs.     

四川盆地丘陵区土壤水分的动态及其随机模拟

土壤水分动态的研究是定量理解植被对水分胁迫响应、土壤养分循环的水文控制、植物水分竞争等生态系统动态的关键,是目前国内外的研究热点。利用2004年-2007年每天的土壤水分监测数据,结合laio土壤水分动态随机模型,研究了四川盆地丘陵区(重庆铜梁虎峰)土壤水分的动态特征及其laio模型在亚热带气候条件推求土壤随机动态特征的适用性。结果表明：监测年内各层土壤水分无论在枯水年还是平水年均差异显著,其中连续平水年土壤水分的含量和变异系数均高于枯水年,枯水年后的平水年低于枯水年;土壤水分的季节变化可分为稳定期、消耗期、波动期;土壤水分的垂直变化来看,土壤水分含量并非完全随着土壤深度的增加而增加。用laio概率随机模型导出的土壤水分概率密度图表明：各层土壤水分的峰度出现在=0.5左右,变化幅度较宽。用laio模型导出的土壤水分峰度和变幅与观测的概率密度函数结果基本一致,相对误差在5%,laio模型可用于分析亚热带气候下土壤水分动态随机特征。     

降雨灌溉蒸发条件下苹果园土壤水分运动数值模拟

根据土壤水动力学原理和果树根区土壤水分运动特点,建立了降雨灌溉蒸发条件下含根系吸水项的二维土壤水分运动数学模型,采用有限元法求解,对降雨灌溉蒸发条件下的地表边界条件进行处理.在田间进行了灌溉蒸发条件下果园土壤水分运动验证试验,采用田间实测土壤含水率分布资料对模型进行验证,结果表明模拟值与实测值吻合较好,所建的根区土壤水分运动模型是正确的,采用有限元法求解是可行的,该模型可用于预测果园田间土壤水分运动.     

不同施肥土壤水分特征曲线空间变异

为了探讨长期施肥土壤水分特征曲线空间变异性及其影响因素,依托中国科学院黄土高原长武农业生态实验站中的长期定位实验,采用高速离心机法测定长期施肥条件下不同吸力的土壤含水率,并利用Van Gennuchten数学模型对水分特征曲线进行拟合,对比研究了不同施肥土壤水分特征曲线、持水性、供水性及土壤水分的有效性。结果表明:由于长期不同施肥使其土壤结构发生差异,导致土壤水分特征曲线存在明显的差异。化肥处理(N、NP)破坏了土壤结构,降低了土壤持水性能;有机肥(M、NPM)的施入增加了土壤有机质的含量,改善了土壤结构,提高了土壤持水性能。有机肥处理(M、NPM)土壤水分的有效性明显高于其他处理,N、NP、CK处理之间无明显差异。土壤供水能力由强到弱为N、CK、NP、NPM、M。