共查询到20条相似文献，搜索用时 250 毫秒
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设计了可以定位、快速、同步测量农田土壤含水率和坚实度的采集仪.在探讨该仪器测量原理和软硬件设计的基础上,对其测量的准确性进行了试验分析.某苗圃地,选定5 m × 5 m的30个采样点,用农田信息采集仪和烘干法分别测量各点的土壤含水率,并对测量值进行简单相关分析,其相关系数为0.917 9,达到极显著性相关.以同样的方式,采用农田信息采集仪和SC900型数字土壤坚实度仪,分别测量30个采样点10 cm和20 cm深度处的土壤坚实度值,并对两种方法在两个深度时的测量值进行相关性分析,其相关系数分别为0.826 7和0.924 5,达到极显著性相关.试验结果表明,该采集仪对农田土壤含水率和坚实度测量的准确性可满足农业生产要求. 相似文献
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农田土壤含水率和坚实度采集仪设计与试验 总被引：1，自引：0，他引：1
设计了可以定位、快速、同步测量农田土壤含水率和坚实度的采集仪。在探讨该仪器测量原理和软硬件设计的基础上,对其测量的准确性进行了试验分析。某苗圃地,选定5m×5m的30个采样点,用农田信息采集仪和烘干法分别测量各点的土壤含水率,并对测量值进行简单相关分析,其相关系数为0.9179,达到极显著性相关。以同样的方式,采用农田信息采集仪和SC900型数字土壤坚实度仪,分别测量30个采样点10cm和20cm深度处的土壤坚实度值,并对两种方法在两个深度时的测量值进行相关性分析,其相关系数分别为0.8267和0.9245,达到极显著性相关。试验结果表明,该采集仪对农田土壤含水率和坚实度测量的准确性可满足农业生产要求。 相似文献
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根区阻抗谱技术可以很好地展现根区水分、生物量等动态变化。针对相邻激励策略下的基质根区100 Hz～2 MHz范围内阻抗谱测量中出现的问题,进行总结、分析,并提出了解决方法。进行了延长通道对测量的影响实验,分析对比了单端口网络和双端口网络补偿策略,实验结果表明,纯基质的测量,单端口网络补偿方法是最佳选择,其步骤简洁且补偿效果显著。通过延长电极长度,使自然条件下阻抗谱可被准确测量的含水率变化范围增大,电极由3 mm增长至8 mm时,适用的含水率范围从8. 35%增大至11. 27%,是原有含水率范围的1. 35倍,有效地减弱了含水率下降时对电极与基质耦合的影响。分析了不同电极长度下的数据差异以及电极几何参数的影响,结果表明,电极长度变化并未对数据的整体趋势变化造成显著影响。同时,对测量中高频时出现负电阻数据的原因进行了分析探讨。 相似文献
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测量土壤水分特征曲线的复合传感器设 总被引：2，自引：1，他引：1
为了直接获取土壤水特征曲线,在一种商品化微型张力计的基础上,设计了一种同步测量土壤水吸力与容积含水率的复合传感器.将张力计中的一段金属保护套管作为天线,利用其辐射阻抗随着土壤含水率变化的规律来测量土壤容积含水率.在实验室环境下,利用3种不同质地土样(砂土、砂壤土、粘壤土)对复合传感器进行了试验,并与经典土壤水特征曲线测量方法(压力锅法结合砂箱法)获得的数据进行了比较.结果表明,复合传感器在3种土壤样品上获得的水分特征曲线的均方根误差均小于0.05,与标准方法所获得的结果具有较好的一致性. 相似文献
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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... 相似文献
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《农业装备与车辆工程》2015,(8)
研究利用土槽试验台车对不同厂家的两种型号旋耕机的动力输入能耗进行对比试验。在对土槽土壤进行调整后,统计测量了表征土壤状态的含水率和坚实度参数以确定旋耕前土壤状态一致性,旋耕后分别测量耕深、耕后土层厚,测算不同机具作业后的膨松度、单位幅宽和耕深截面的功率消耗数据,对两型旋耕机能耗进行对比,指出了将能耗参数纳入旋耕机质量检验与评价的必要性。 相似文献
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基于含水率与温度补偿的土壤pH值在线实时检测系统 总被引：1，自引：0，他引：1
针对目前常用土壤pH值传感器在测量过程中受土壤含水率和温度影响较大的问题,设计了带有温度、含水率补偿模型的锑电极土壤pH值在线实时检测系统。利用最小二乘法对pH值和测量结果进行线性分析,补偿土壤pH值测量误差。试验结果表明,经过补偿之后,由温度和含水率变化导致的pH值测量误差至少可降低84. 5%,pH值测量值随温度和含水率的变化幅度不超过±0. 1。与市场产品ZD-18型土壤酸度计、HYSWR-ARC-12V型土壤含水率传感器、水银温度计对比研究得出,3项指标线性拟合决定系数均达到0. 99以上。为了确保自然环境下土壤pH值测量的适用性,探索了系统在使用过程中土壤含水率的阈值与测量精度,表明在土壤体积含水率大于5%的情况下均可有效测量。试验表明,在pH值3. 06～10. 36范围之内,本系统可有效测量,检测误差为-1. 53%～3. 51%,满足土壤pH值实时在线测量要求。 相似文献
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Xiao-Ling Wang Guo-Jun Sun Feng-Min Li Jin-Zhang Xu 《Agricultural Water Management》2008,95(3):190-198
The alfalfa pastureland in the semiarid Loess Plateau region of Northwest China usually has dry soil layers. A field experiment was conducted from October 2000 to October 2004 to examine soil water recovery and crop productivity on a 9-year-old alfalfa pasture. This experiment included six treatments: alfalfa pasture for 10-14 years, a conventional farming system without prior alfalfa planting, and four alfalfa-crop rotation treatments. For the rotation treatments, after 9 years of alfalfa selected crops were planted from 2001 to 2004 in the following sequence: (1) millet, spring wheat, potatoes, peas; (2) millet, corn, corn, spring wheat; (3) millet, potatoes, spring wheat, corn; (4) millet, fallow, peas, potatoes. The results showed that dry soil layers occurred in alfalfa pasture. We then plowed the alfalfa pasture and planted different crops. The soil water gradually increased during crop growth in the experimental period. The degree of soil water recovery in the four alfalfa-crop rotation treatments was derived from comparison with the soil water in the conventional system. After 4 years, the soil water recovery from the alfalfa-crop rotation systems at 0-500 cm soil depth was 90.5%, 89.8%, 92.2% and 96.7%, respectively. Soil total N content and soil respiration rate were high in the alfalfa-crop rotation systems. The yields of spring wheat in 2002, peas in 2003 and potatoes in 2004 in the alfalfa-crop rotation systems were not significantly different from yields in the conventional system. In the alfalfa-crop rotation systems, the yields of spring wheat and peas were greatly influenced by rainfall and were lowest in the dry year of 2004; the yields of corn and potatoes had a direct relationship with water use and were lowest in 2003. In summary, soil water in dry soil layers can recover, and crop yields in the alfalfa-crop systems were equal to those of the conventional system. 相似文献
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The Richards equation has been widely used for simulating soil water movement. However, the take-up of agro-hydrological models using the basic theory of soil water flow for optimizing irrigation, fertilizer and pesticide practices is still low. This is partly due to the difficulties in obtaining accurate values for soil hydraulic properties at a field scale. Here, we use an inverse technique to deduce the effective soil hydraulic properties, based on measuring the changes in the distribution of soil water with depth in a fallow field over a long period, subject to natural rainfall and evaporation using a robust micro Genetic Algorithm. A new optimized function was constructed from the soil water contents at different depths, and the soil water at field capacity. The deduced soil water retention curve was approximately parallel but higher than that derived from published pedo-tranfer functions for a given soil pressure head. The water contents calculated from the deduced soil hydraulic properties were in good agreement with the measured values. The reliability of the deduced soil hydraulic properties was tested in reproducing data measured from an independent experiment on the same soil cropped with leek. The calculation of root water uptake took account for both soil water potential and root density distribution. Results show that the predictions of soil water contents at various depths agree fairly well with the measurements, indicating that the inverse analysis is an effective and reliable approach to estimate soil hydraulic properties, and thus permits the simulation of soil water dynamics in both cropped and fallow soils in the field accurately. 相似文献
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An index of soil drought intensity and degree: An application on corn and a comparison with CWSI 总被引：2，自引：0，他引：2
A variety of indices have been used to measure soil and crop drought for irrigation scheduling. However, simple indices with physiological mechanisms from soil water content are still expected. Based on the water flow and supply in a soil-plant continuum, we examined the concepts of soil drought intensity and drought degree and found an empirical correlation between soil water storage and depletion in a given layer. Accordingly, an index of soil drought intensity (I) and degree (D) was established using the soil water data obtained from a field experiment conducted in Xianning, Hubei, China. Corn plants (Zea mays L., Yedan 13) were grown at field plots under a movable rain shelter. From the V6 stage to R1 stage, the corn plants were grown under seven soil water deficit levels, by no irrigation applied for 0-36 days in 2005 and 0-32 days in 2006. At the end of the irrigation withholding period, it was found that soil water below 70 cm still remained at high level, but the soil water was not easily transported to the root zone in the upper layer. The daily values of I in different soil layers reflected the soil water depletion rates in the drying course. The values of D in different soil layers, which were calculated from I, increased with the progressive soil drying course. The D index in different soil layers not only revealed the drought severity of the layer, but it was also inversely correlated with corn yields when D was less than the threshold values. When D went beyond the thresholds, for example 0.68 in 2005 (soil dried 25 days) and 0.70 in 2006 (soil dried 17 days) in the 0-10 cm soil layer, the corn yield was reduced significantly. Based on soil water changes, index D is the comprehensive result of antecedent soil water condition, crop growth and root development, soil properties, and potential atmospheric evaporation. It is also comparable to the development of drought hazard on a crop. The results suggest that soil drought degree D, together with I, can be an index for monitoring and evaluating soil-crop drought, as well as complementing the crop water stress index (CWSI) in irrigation scheduling. 相似文献
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Managing natural resources of watersheds in the semi-arid tropics for improved soil and water quality: A review 总被引：1，自引：0，他引：1
Soil, water and production systems constitute the most important natural resources of a watershed in the rainfed agro-ecosystem; and for sustainability of the production systems they need to be in harmony with the environment. To learn from the past research, a review is made of literature on the impact of natural resource management practices on soil and water quality in the semi-arid tropical regions of India. The results from long-term on station field experiments show that an integrated use of soil and water conservation practices with balanced plant nutrition can not only sustain increased productivity but also maintain soil quality at the watershed or catchment level. Natural resource management practices that conserve soil and water also help to maintain surface and groundwater quality. The changes in soil and water quality, as impacted by natural resource management practices, need to be monitored and assessed on a continuing basis as the outcome of such research offers valuable opportunity for the implementation of corrective management practices, as and when needed. 相似文献
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Water uptake by plant roots is an important process in the hydrological cycle, not only for plant growth but also for the role it plays in shaping microbial community and bringing in physical and biochemical changes to soils. The ability of roots to extract water is determined by combined soil and plant characteristics, and how to model it has been of interest for many years. Most macroscopic models for water uptake operate at soil profile scale under the assumption that the uptake rate depends on root density and soil moisture. Whilst proved appropriate, these models need spatio-temporal root density distributions, which is tedious to measure in situ and prone to uncertainty because of the complexity of root architecture hidden in the opaque soils. As a result, developing alternative methods that do not explicitly need the root density to estimate the root water uptake is practically useful but has not yet been addressed. This paper presents and tests such an approach. The method is based on a neural network model, estimating the water uptake using different types of data that are easy to measure in the field. Sunflower grown in a sandy loam subjected to water stress and salinity was taken as a demonstrating example. The inputs to the neural network model included soil moisture, electrical conductivity of the soil solution, height and diameter of plant shoot, potential evapotranspiration, atmospheric humidity and air temperature. The outputs were the root water uptake rate at different depths in the soil profile. To train and test the model, the root water uptake rate was directly measured based on mass balance and Darcy's law assessed from the measured soil moisture content and soil water matric potential in profiles from the soil surface to a depth of 100 cm. The ‘measured’ root water uptake agreed well with that predicted by the neural network model. The successful performance of the model provides an alternative and more practical way to estimate the root water uptake at field scale. 相似文献
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干旱区滴灌均匀系数对土壤水氮分布影响模拟 总被引：1，自引：0，他引：1
基于HYDRUS-2D软件建立了棉花膜下滴灌水氮运移模型,利用干旱区棉花膜下滴灌试验数据对模型进行了参数率定和验证。将灌水器流量沿毛管的变化离散为依次逐段减小,并假设土壤水分在各段之间不存在交换,利用验证后的数学模型研究了干旱区不同滴灌均匀系数时土壤水氮分布特征,评估了土壤空间变异对水氮分布均匀性的影响。模拟结果表明,随着灌水的进行,滴灌均匀系数Cu为0.60和0.80时,土壤含水率和NO-3-N质量浓度均匀系数均呈下降趋势,而Cu=0.95时变化较平稳;滴灌均匀系数越低,灌水后土壤含水率和NO-3-N质量浓度均匀系数降低的幅度越大;土壤NO-3-N质量浓度均匀系数的变化范围为0.35~1.00,低于土壤含水率均匀系数。田间试验存在的土壤空间变异在一定程度上增加了土壤水氮分布不均匀性。 相似文献
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不同沟灌方式下夏玉米棵间蒸发试验 总被引：5，自引：0，他引：5
采用常规沟灌和交替隔沟灌技术,研究了不同水分处理(水分控制下限为田间持水率的80%、70%、60%)夏玉米的棵间蒸发。结果表明:常规沟灌的灌后蒸发和全生育期棵间蒸发量均大于交替隔沟灌,灌水后短期内由于表层土壤含水率较高,土壤蒸发较大;在满足作物蒸腾耗水的基础上,交替隔沟灌减小了灌溉湿润面积而减小无效蒸发耗水;不同沟灌方式下土壤蒸发与表层土壤含水率呈明显的脉冲波动变化,而深层土壤含水率波动较弱;表层土壤含水率和叶面积指数对棵间蒸发影响明显,二者与相对土面蒸发强度均有良好的指数函数关系。水分下限控制合适,交替隔沟灌棵间蒸发与蒸腾耗水明显降低,是夏玉米适宜的灌水方式。 相似文献
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覆膜滴灌条件下土壤改良剂对土壤导气率的影响 总被引：4，自引：0，他引：4
为研究覆膜条件下土壤改良剂对土壤导气率的影响,进行田间对照试验分析。结果表明:施加改良剂对土壤颗粒机械组成没有明显改变,但使土壤容重明显减小、饱和含水率升高、田间持水率升高;覆膜条件有保水保墒作用,但阻碍了土壤空气与外界气体的交换,使土壤导气率降低;改良剂的施加改善了土壤结构和土壤物理性状,促进了土壤孔隙内气体流通,使土壤导气率增大;石膏对导气率的改善效果最显著,聚丙烯酰胺(PAM)次之,旱地龙的改善效果最低;PAM和旱地龙的中、高施量比低施量改善效果更显著,石膏的中、低施量对导气率的改善效果相近,高施量处理下导气率为低施量处理的1.12倍。说明土壤改良剂对土壤导气率有较好的改善效果。 相似文献
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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. 相似文献