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1.
《Agricultural Water Management》1998,37(1):1-19
Knowledge of the spatial variability of soil–water properties is of primary importance for management of agricultural lands. This study was conducted to examine which spatial structure measure, the semi-variogram or the covariance variogram, is appropriate for inference of the spatial structure and performing interpolation of soil–water properties from sample data sets. Using the appropriate spatial structure measure, the spatial variability of these properties (saturated hydraulic conductivity, water table depth, groundwater salinity, and soil salinity and sodicity) as affected by subsurface drainage is also evaluated. The soil–water properties were sampled before and after the installation of subsurface drainage on a regular square grid of 500 m at 61 locations within 1470 ha in the Nile Delta of Egypt. The results showed that the covariance variogram reveals the character of spatial structure and that it is more appropriate for interpolation than the semi-variogram. Subsurface drainage has highly affected the spatial variability of soil–water properties. On average, the spatial correlation range increased by approximately 29%, whereas the ratio of structural heterogeneity to the total variation (relative structured heterogeneity) was doubled 4 years after drainage installation. Moreover, the nugget effect increased and was present for all soil–water properties with noticeably high values. Uneven spatial distributions were also observed. Further study of long-term spatial variation of soil–water properties as affected by subsurface drainage is suggested. 相似文献
2.
《Agricultural Water Management》2001,47(2):155-178
The method for verification of numerical solution of water flow towards a drain in homogeneous soil under steady rainfall or steady irrigation recharge is presented in the paper. In 1979, Zaradny and Feddes proved that the accuracy of the numerical result depended, among other things, on the size and pattern of discretization applied. Ibidem, a partly verification of numerical solution was presented. It was based on the Thiem–Dupuit well formula and on the hodograph solutions given by Van Deemter [Van Deemter, J.J., 1950. Versl. Landb. Onderz. 56 (7), 1–67] and Childs [Childs, E.C., 1959. J. Soil Sci. 10 (1), 83–100]. Up till now, there was no full verification of this solution. The proposed method which depends on replacement of the drain by horizontal ‘well’ in a confined aquifer of a constant thickness, the geometry of which in the x–z plane is compatible, in shape and size, with saturated zone in the numerical solution gives the possibility of such verification. For this problem groundwater flow can be described by the Laplace equation. The analytical solutions for the hydraulic head φ and the stream function ψ, specification of boundary conditions for the considered problem and the method of determination of the Fourier series constants are given in the paper. Presented results confirm the correctness of numerical solution given by Zaradny and Feddes [Zaradny, H., Feddes, R., 1979. Agric. Water Manage. 2, 37–53] and they also show that when verification with respect to observed and measured data is impossible, such tests should be performed. 相似文献
3.
Ibrahim Mubarak Rafael Angulo-Jaramillo Jean Claude Mailhol Mohammadreza Khaledian Michel Vauclin 《Agricultural Water Management》2010,97(10):1517-150
The management of irrigated agricultural fields requires reliable information about soil hydraulic properties and their spatio-temporal variability. The spatial variability of saturated hydraulic conductivity, Ks and the alpha-parameter αvG-2007 of the van Genuchten equation was reviewed on an agricultural loamy soil after a 17-year period of repeated conventional agricultural practices for tillage and planting. The Beerkan infiltration method and its algorithm BEST were used to characterize the soil through the van Genuchten and Brooks and Corey equations. Forty field measurements were made at each node of a 6 m × 7.5 m grid. The soil hydraulic properties and their spatial structure were compared to those recorded in 1990 on the same field soil, through the exponential form of the soil hydraulic conductivity given by the Gardner equation, using the Guelph Pressure Infiltrometer technique. No significant differences in the results obtained in 1990 and 2007 were observed for either particle-size distribution or dry bulk density. The mean value of αvG-2007 was found to be identical to that of αG-1990, while that of Ks-2007 was significantly smaller than that of Ks-1990. In contrast to the Gardner equation, the van Genuchten/Brooks and Corey expression was found to be more representative of a well-graded particle-size distribution of a loamy soil. The geostatistical analysis showed the two parameters, Ks and αvG-2007, were autocorrelated up to about 30 and 21 m, respectively, as well as spatially positively correlated within a range of 30 m. Despite the difference in the mean values of Ks between the two studies, the spatial structures were similar to those found in the 1990 experiment except for the covariance sign. The similarity in autocorrelation ranges indicate that the spatial analysis of soil hydraulic properties is independent of the infiltration methods (i.e., measurement of an infiltration flux) used in the two studies, while the difference in the covariance sign may be linked to the use of two different techniques of soil hydraulic parameterization. The covariance values found in the 2007 campaign indicates a positive relationship between the two parameters, Ks and αvG-2007. The spatial correlations of soil hydraulic parameters appear to be temporally stabilized, at least within the agro-pedo-climatic context of the study. This may be attributed to the soil textural properties which remain constant in time and to the structural properties which are constantly renewed by the cyclic agricultural practices. However, further experiments are needed to strengthen this result. 相似文献
4.
《Agricultural Water Management》2001,51(3):173-185
Study was undertaken to assess the water use, moisture extraction and water use efficiency (WUE) of irrigated wheat, when grown in association with boundary plantation of poplar, at different distances (0–3, 3–6, 6–9, 9–12, 12–15 and >15 m (control)) from poplar (Populus deltoides M.) tree line. Presence of 3-year old poplar plantation at the boundary of wheat field caused 7.5% higher water use than control (plots having no effect of tree line) up to 3 m distance from tree line which further intensified up to 12.7% and extended up to 6 m distance with 4-year old plantation. Similarly, maximum moisture extraction, both laterally and vertically, observed near the tree line. Contrary to this, WUE of wheat was reduced by 4.6% between 0 and 3 m distance from tree line with 3-year old plantation, decline intensified further to 18.6% with 4-year old plantation. However, wheat was benefited by boundary plantation of trees between 3 and 9 m distance from the base of the tree line which resulted in increased WUE of the wheat crop up to 9%. 相似文献
5.
《Agricultural Water Management》2001,51(1):53-78
Intensification of the agricultural sector and the increase in quantity and decrease in quality of municipal and industrial wastewater, in particular during the past decades, resulted in many industrial countries, such as Belgium, in a sharp degradation of surface water and groundwater. To control the current degree of contamination and reduce the environmental impact of the agricultural sector, the Flemish government recently introduced a number of regulations aiming at controlling the use of nitrogen fertilisers. To facilitate the implementation and the control of the new regulations, threshold values of allowable doses of organic and inorganic nitrogen fertilisers, and their spreading in time were made soil independent. As the soil physical, chemical and biological response depends on the geohydrology of the site and the past fertilisation practice, fertiliser standards applied on different soil–crop systems result in different leaching patterns.To assess the effect of the soil on the nitrogen leaching, a number of past experimental field trials were analysed using the WAVE model as modelling tool for the reconstruction of the nitrogen dynamics. As a first step in the study, the historic data of the field experiments were used to calibrate and validate the WAVE model. The deterministic calibration and validation of the WAVE model yielded a set of model parameters for the examined soil–crop–fertiliser practice conditions. The bottlenecks in the calibration were the nitrogen mineralisation parameters and the initialisation and subdivision of the soil organic matter over the different organic pools. The model validation, being the second step in the study, revealed the power of the WAVE model to predict the evolution and transformations of nitrogen in the soil profile and the leaching of nitrate at the bottom of the root zone. In a third step, the WAVE model was used in a scenario-analysis exercise to examine the factors effecting the amount of nitrate leached at the bottom of the root zone. This analysis revealed that the nitrate leached out of the soil profile is controlled by the fertiliser practice, the rainfall depth and its distribution, the soil texture, the soil mineralisation capacity and the past fertilisation practice. 相似文献
6.
A priori knowledge of the in situ soil field water capacity (FWC) and the soil-water retention curve for soils is important
for the effective irrigation management and scheduling of many crops. The primary objective of this study was to estimate
the in situ FWC using the soil-water retention curve developed from volumetric water content (θ), and water potential (ψ) data collected in the field by means of soil moisture sensors in two contrasting-textured soils.
The two study soils were Lihen sandy loam and Savage clay loam. Six metal frames 117 cm × 117 cm × 30 cm high were inserted
into the soil to a depth of 5–10 cm at approximately 40 m intervals on a 200 m transect. Two Time Domain Reflectrometry (TDR)
sensors were installed in the center of the frame and two Watermark (WM) sensors were installed in the SW corner at 15 and
30 cm depths to continuously monitor soil θ and ψ, respectively. A neutron probe (NP) access tube was installed in the NE corner of each frame to measure soil θ used
for TDR calibration. The upper 50–60 cm of soil inside each frame was saturated with intermittent application of approximately
18–20 cm of water. Frames were then covered with plastic tarps. The Campbell and Gardner equations best fit the soil–water
retention curves for sandy loam and clay loam soils, respectively. Based on the relationship between soil ψ and elapsed time
following cessation of infiltration, we calculated that the field capacity time (t
FWC) were reached at approximately 50 and 450 h, respectively, for sandy loam and clay loam soils. Soil-water retention curves
showed that θ values at FWC (θ
FWC) were approximately 0.228 and 0.344 m3 m−3, respectively, for sandy loam and clay loam soils. The estimated θ
FWC values were within the range of the measured θ
FWC values from the NP and gravimetric methods. The TDR and WM sensors provided accurate in situ soil–water retention data from
simultaneous soil θ and ψ measurements that can be used in soil-water processes, irrigation scheduling, modeling and chemical
transport. 相似文献
7.
Jiajie He Mark Dougherty Francisco J. Arriaga John P. Fulton Charles W. Wood Joey N. Shaw Clifford R. Lange 《Irrigation Science》2013,31(1):59-67
The Alabama Black Belt area is widespread of Vertisols that are generally unsuitable for conventional septic systems; nonetheless, systems of this type have been widely used in this region for decades. In order to explore alternatives for these conventional septic systems, a real-time soil moisture–controlled subsurface drip irrigation wastewater disposal system was integrated and field tested in a Houston Vertisol for 1 year. This automated disposal system effectively limited wastewater disposal during unfavorably wet drain field conditions. However, the resulting nutrient supply into the drain field was observed to be in surplus to crop growth requirements. Soil cores taken at the conclusion of the 1-year study indicated evidence of nitrate and phosphorus leaching. Available nitrates in the top 100 cm of soil showed a decreasing trend but were higher than all other parallel controls. Soil crop-available phosphorous in the soil increased below the drip line, as result that may be ascribed to soil cracking that was not properly controlled at the test site. Despite the demonstrated deficiencies, integrating timing of wastewater disposal with soil moisture conditions can supplement existing municipal or decentralized community wastewater treatment disposal systems. 相似文献
8.
Baozhong Zhang Yu Liu Di Xu Nana Zhao Bo Lei Ricardo D. Rosa Paula Paredes Teresa A. Paço Luis S. Pereira 《Irrigation Science》2013,31(6):1303-1316
An accurate estimation of crop evapotranspiration (ET c) is very useful for appropriate water management; hence, an accurate and user-friendly model is needed to support related irrigation decisions. In this view, a study was developed aimed at estimating the ET c of winter wheat–summer maize crop sequence in the North China through eddy covariance measurements, to calibrate and validate the SIMDualKc model, to estimate the basal crop coefficients (K cb) for both crops and to partition ET c into soil evaporation and crop transpiration. Two years of field experimentation of that crop sequence were used to calibrate and validate the SIMDualKc model and to derive K cb using eddy covariance measurements. Various indicators have shown the goodness of fit of the model, with estimated values very close to the observed ones and estimate errors close to 0.5 mm d?1. The initial, mid-season and end basal crop coefficients for wheat were 0.25, 1.15 and 0.30, respectively, and those for maize were 0.15, 1.15 and 0.45, thus close to those proposed in FAO56 guidelines. The soil evaporation represented near 80 % of ET c for the initial stages of winter wheat and summer maize and decreased to only 5–6 % during the mid-season period. Evaporation during the full crop season averaged 28 % for winter wheat and 40 % for summer maize. The importance of wetting frequency and crop ground coverage in controlling soil evaporation was evidenced. 相似文献
9.
《Agricultural Water Management》2001,50(1):41-52
New time-domain reflectometry (TDR) probes were developed for estimating moisture conditions near the soil surface. Two types of probes, knife-shaped (K) and surface (S) types, were devised, and their performance was investigated in comparison with conventional rod-type probes. The K-type probe consists of two parallel, knife-shaped electrodes that can move in the shallow soil-layer without drawing out. The S-type probe looks like a sled with two parallel edges (electrodes), and can slide smoothly over the soil surface. This probe uses only the lower half of the electromagnetic field around the electrodes, but the estimates of moisture contents were comparable to those by conventional rod-type probes. The new probes would expand the applications of TDR principle especially to “non-penetrating” or “on-the-move” measurements of moisture conditions near the soil surface. 相似文献
10.
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12.
Shahbaz Khan Tariq Rana Munir A. Hanjra John Zirilli 《Agricultural Water Management》2009,96(3):493-503
Agricultural water markets can facilitate adjustments to water scarcity and competition and enhance economic efficiency, but markets cannot automatically balance efficiency, equity and environmental sustainability goals. The consequences of water trading on soil salinity in irrigation areas are not yet fully understood, but recognized as an issue that needs to be analysed. This paper explores the nexus between water trading and groundwater-induced soil salinity in a selected irrigated area in the Murray-Darling Basin. Results show that minimum irrigation intensities must be met to flush salts out of the root zone especially in shallow water table/high salinity impact areas. Such minimum irrigation intensities are helpful but not necessarily in deep water table/low salinity impact areas. Should water markets lead to permanent water transfers out of mature irrigation areas, minimum irrigation intensity needs might not be met in high salinity impact areas, causing substantial negative impacts on resource quality and agricultural productivity. Water trading that adds to salinity cannot be economically viable in the long run. The tradeoffs between water trading and environmental and equity goals need to be determined. This work contributes to the wider debate on Australian water policy aimed at achieving water security through water trading in the Murray-Darling Basin. 相似文献
13.
The effect on productive and vegetative behavior and on the quality of oil from Olea europaea L. when applying two distinct irrigation techniques, full irrigation (FI) and regulated deficit irrigation (RDI), was studied. A total of five wet soil volumes (WSVs, 12, 24, 35, 47 and 59%) expressed in terms of the potential root exploration volume were established for each strategy. The experiment was performed on cv. ‘Arbequina’ in an olive grove in Tarragona (Spain). Results obtained suggest that a 20% reduction in the irrigation dose (RDI) had no significant effect either on olive fruit and oil production or on oil content. Likewise, no significant increase in irrigation water-use efficiency was observed for FI with respect to RDI. A tendency for olive and oil production per hectare to increase with increased WSV percentage was observed, although there were no significant differences between FI and RDI except for 59% WSV in the RDI strategy, producing the best response. 相似文献
14.
Capillary rise represents an often neglected fraction of the water budget that contributes to crop water demand in situations of shallow groundwater levels. Such a situation is typical in irrigated areas of Central Asia where water from capillary rise is exploited by farmers to meet production targets in Uzbekistan under uncertain water supply. This leads to higher water inputs than needed and creates a vicious cycle of salinization that ultimately degrades the agricultural land. In this study, capillary rise is quantified at different spatial scales in the Shomakhulum Water Users Association (WUA), situated in the southwest of Khorezm, Uzbekistan. The mathematical model HYDRUS-1D was used to compute the capillary rise at field level for three major crops (cotton, wheat and vegetables) on six different hydrological response units (HRUs). These six HRUs having homogenous groundwater levels (1–2 m beneath the soil surface) and soil texture were created using GIS and remote-sensing techniques. Capillary rise from these HRU was then up-scaled to WUA level using a simple aggregation approach. The groundwater levels simulated by FEFLOW-3D model for these HRUs in a parallel study under four improved irrigation efficiency scenarios (S-A: current irrigation efficiency or business-as-usual, S-B: improved conveyance efficiency, S-C: increased application efficiency and S-D: improved conveyance and application efficiency) were then introduced into HYDRUS-1D to quantify the impact of improved efficiencies on the capillary rise contribution. Results show that the HRUs with shallow groundwater-silt loam (S-SL), medium groundwater-silt loam (M-SL) and deep groundwater-silty clay loam (D-SCL) have capillary rise contribution of 28, 23 and 16 % of the cotton water requirements, 12, 5 and 0 % of the vegetable water requirements and 9, 6 and 0 % for the wheat water requirements, respectively. Results of the scenarios for the whole WUA show that the maximum capillary rise contribution (19 %) to the average of all crops in the WUA was for the S-A scenario, which reduced to 17, 11 and 9 % for S-B, S-C and S-D, respectively. Therefore, it is recommended that before any surface water intervention or drainage re-design, water managers should be informed about the impacts on groundwater hydrology and hence should adopt appropriate strategies. 相似文献
15.
《农业机械学报》1989,(1)
Luoyang Instituti of Technology (former Luoyang Agricultural Machinery Institute) is a high engineering institute under the command of the Ministry of Machine Manufacture and Electronics Industry It is located in Luoyang, the ancient capital of nine dynasties, which has strong in science and tech- 相似文献
16.
ressure Gauge 《农机使用与维修》2007,(3)
voirDu Jiying Gao Baoguo Yuan Mei Jin Pingxin(Hekou Oil Production Plant,Shengli Oilfield Branch Company,Dongying,Shandong,257200,China)According to characteristics of Boshen-6 buried hill reservoir,including deep depth,and high temperature(>170°),the capillary-steel-pipe pressure gauge system were introduced to well test the Boshen buried hill reservoir.The well test data were used to investigate the reservoir's geological characteristics,to determine the reservoir's type,to clarify the interwell connectivity and to provide the reliable basi 相似文献
17.
LI Zhongjie FEI Liangjun HAO Kun LIU Teng CHEN Nanshu ZHANG Quanju HUANG Deliang 《排灌机械工程学报》2020,38(7):713-719
Six-year old apple trees were selected for field experiment. The objective of this study was to obtain the reasonable arrangement of surge-root irrigation emitters in apple orchards. There were three factors: the buried depth H( 25,40,55 cm),the horizontal distance L( 30,40,60 cm) between the emitters and the trunk of the experimental tree,and the number of the irrigation emitters N( 1,2,4). The effect of the arrangement of surge-root irrigation emitters on the growth,yield and irrigation water use efficiency( IWUE) of apple trees were studied in Northern Shaanxi where the irrigation quota takes 60%-75% of the field water capacity. The results showed that the arrangement of emitters for surge-root irrigation had a significant effect on apple tree yield and IWUE,especially,the yield and IWUE reached 28 388. 17 kg/hm2 and 16. 83 kg/m3 in treatment T3,respectively. At the same L and N levels( T1,T2,and T3),the yield and IWUE in treatment T3 were the highest,and the yields in treatments T1 and T2 were decreased by 26.22% and 31.48%,while IWUE is reduced by14.02% and 18.12% compared with T3,respectively. At the same H and N levels( T3,T4,and T5),the yield and IWUE of apple trees were decreased with increasing L level. Especially,when L was 30 cm( T3),the yield and IWUE were the highest. The same L and H levels( T3,T6,and T7) could promote the growth of apple trees when N was 2( T3). Compared with treatment T3,it was found that the increment of new shoots was decreased by 8.07%-18.71%,and the fruit diameter was decreased by 5.41%-9.11%. Therefore,two emitters should be arranged symmetrically on both sides of an apple tree,each was buried at a 40 cm depth and 30 cm away from the trunk of the tree to effectively improve the yield and IWUE of the apple tree in mountainous areas in Northern Shaanxi. 相似文献
18.
《农业机械学报》2003,(4)
The discipline of Agricultural Mechanization Engineering in Shandong University of Technology is thefirst one in the history of the University with its own superiority and characteristics in the development ofdiscipline and professional training.About 40 0 0 undergraduate students have graduated from the disci-pline,34graduate students have enrolled M.Sc.program and1 1 students have enrolled joint- training Ph Dprogram with other universities in the area of agricultural mechanization engin… 相似文献
19.
Wang L.Li S.Wang Y.Wang X. 《灌溉排水学报》2019,(11):65-73
【Objective】In order to obtain the irrigation infiltration recharge coefficient in the lower reaches of Aksu river and improve the numerical simulation accuracy of groundwater in the study area,the influencing factors of the irrigation infiltration recharge coefficient in this area were analyzed. 【Method】In this paper,field sampling and indoor irrigation experiments were carried out by selecting representative points under different irrigation schemes,vadose zone thickness and soil structure in the lower Aksu area,and numerical simulation of vadose zone flow was carried out in combination with Hydrus-1d. Hydrus-1d model was used to calculate irrigation inflow under this soil structure by changing irrigation schemes and vadose zone thickness. Change of seepage recharge coefficient. On the basis of the calculation results of the model,the relationship between irrigation schedule,aeration zone thickness and irrigation infiltration recharge coefficient is analyzed firstly,and then the main factors affecting irrigation infiltration recharge coefficient in soil structure are analyzed with the method of model calculation and mathematical statistics. 【Result】The results showed that the irrigation infiltration recharge coefficient ranged from 0.320 to 0.474 under drip irrigation and from 0.408 to 0.561 under border irrigation. The irrigation infiltration recharge coefficient varied under different irrigation schemes,while the irrigation infiltration recharge coefficient decreased with the increase of aeration zone thickness. The main factors affecting irrigation infiltration recharge are soil permeability coefficient,soil bulk density and initial soil water content. 【Conclusion】According to indoor experiment combined with numerical model to calculate the irrigation infiltration coefficient under different irrigation system range, it is concluded that the influence factors of irrigation infiltration coefficient of irrigation system, the thickness of the vadose zone and reflects soil permeability coefficient of soil structure, soil quality and soil initial moisture content, volume for the downstream area irrigation infiltration coefficient selection in arid areas and provides the theory basis for further research. © 2019 Journal of Irrigation and Drainage. All rights reserved. 相似文献
20.
Ian Moorhouse 《Irrigation and Drainage Systems》1999,13(2):165-187
This paper presents a case study of Goulburn-Murray Water's approach to the development and implementation of its asset management program for irrigation infrastructure. The success and effectiveness of asset management is not a matter of technical aspects only, rather it depends on an integrated package of institutional, organisational, technical and financial aspects. 相似文献