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1.
The effects of supplemental irrigation and irrigation practices on soil water storage and barley crop yield were studied for a crust-forming soil at the University of Jordan Research Station near Al-Muwaqqar village during the 1996/97 growing season. An amount of 0.0, 48.9, 73.3, 122.2 and 167 mm supplemental irrigation water were applied. The 48.9, 73.3 and 122.2 mm applications were applied through surface irrigation into furrows with blocked ends, and the 0.0 and 167 mm applications via sprinkler irrigation. The greatest water infiltration and subsequent soil storage was achieved with the 122.2 mm application followed by the 73.3 mm irrigation, both surface applied. Application efficiency (the fraction of applied water that infiltrated into the soil and stored in the 600 mm soil profile) and soil water storage associated with supplemental blocked furrow irrigation was significantly greater than with supplemental sprinkler irrigation. For arid zone soil, which has little or no structural stability, application of supplemental irrigation water via short, blocked-end furrows prevents runoff and increases the opportunity time for infiltration, thereby increasing the amount of applied water that is infiltrated into the soil and stored in the soil profile. Supplemental irrigation, applied by a low-rate sprinkler system, was not as effective because of the low infiltration rates that resulted from the development of a surface throttle due to dispersion of soil aggregates at the soil surface. The differences in stored water had a significant effect on grain and straw yields of barley. Without supplemental irrigation, barley grain and straw yields were zero in natural rainfall cultivation with a total rainfall of 136.5 mm. Barley yields in the control treatment, with a 167 mm supplemental sprinkler irrigation were low being 0.19 and 1.09 ton/ha of barley grain and straw, respectively. Supplemental irrigation through blocked-end furrows increased barley grain and straw yields significantly compared with supplemental sprinkler irrigation to a maximum of 0.59 and 1.8 ton/ha, respectively. The improvement coming from the increased water storage associated with furrows. Since irrigation water is very limited if available, farmers are encouraged to form such furrows for reducing runoff from rainfall thereby increasing the amount of water available for forage and field crop production.  相似文献   

2.
The effects of irrigation methods, application rates and initial moisture content on soil water storage and surface runoff were studied in soils liable to surface crust formation during 1995–1996 at the University of Jordan Research Station near Al-Muwaqqar village. Four irrigation methods were tested (sprinkler, furrow, basin and trickle) and four application rates (6.2, 14.4, 24.4 and 28.4 mm/h). Two runs were performed (soil initially dry and soil initially wet). Basin irrigation provided the highest application efficiency followed by trickle, sprinkler and furrow irrigation methods. Entrapping water by the basin borders increased soil water storage by allowing more water to infiltrate through the surface crust. Decreasing the application rate from 28.4 to 6.2 mm/h increased soil water storage significantly in all 150 mm layers to a depth of 600 mm. If the soil was already wet, soil moisture storage decreased owing to siltation during the prewetting and formation of a surface crust and low soil water storage capacity. A sedimentary crust formed at the bottom of the furrows in the furrow irrigation treatment, which reduced soil water storage and increased surface runoff significantly owing to the reduction in infiltration. Increasing the application rate from 6.2 to 28.4 mm/h in the furrow surface irrigation treatment increased the runoff discharge 10-fold. Even with the lowest application rate the runoff coefficient under sprinkler irrigation was 20.3% indicating high susceptibility of Al-Muwaqqar soils to surface crust formation.  相似文献   

3.
Water conservation strategies for center pivot and furrow irrigation in the Central Platte Valley of Nebraska were evaluated using computer simulation. Irrigation requirements, grain yield, return flow and net depletion (gross irrigation minus return flow) of groundwater were simulated for a period of 29 years for Hord and Wood River silt loam soils. Grain yields were simulated for a typical corn variety for non-limiting water supplies (maximum attainable yield), for two levels of deficit irrigation (irrigation limited to certain growing periods), and for dryland conditions. Additional simulations were performed for a short-season corn, grain sorghum, and soybeans. The impacts of tillage practices on water conservation were also investigated.Center pivot irrigation on the Hord silt loam required 75–125 mm/year less water application than furrow irrigation. For the Wood River silt loam, water applications were the same for both irrigation systems. Applied water depths were reduced by an additional 75–125 mm using deficit irrigation with only a small reduction in yield. Return flow to the groundwater was small for well-managed pivots but high for some furrow irrigation systems based on the assumption that all deep percolation returns to the aquifer in the Central Platte Valley. Net depletion (gross irrigation minus return flow) of the groundwater for a center pivot with LEPA was 50 mm (17%) less than a center pivot with impact sprinklers. Ridge till had a net depletion 50 mm (25%) less than conventional tillage (double disk, plant) for furrow systems.  相似文献   

4.
A 3-year project compared the operation of a subsurface drip irrigation (SDI) and a furrow irrigation system in the presence of shallow saline ground water. We evaluated five types of drip irrigation tubing installed at a depth of 0.4 m with lateral spacings of 1.6 and 2 m on 2.4 ha plots of both cotton and tomato. Approximately 40% of the cotton water requirement and 10% of the tomato water requirement were obtained from shallow (<2 m) saline (5 dS/m) ground water. Yields of the drip-irrigated cotton improved during the 3-year study, while that of the furrow-irrigated cotton remained constant. Tomato yields were greater under drip than under furrow in both the years in which tomatoes were grown. Salt accumulation in the soil profile was managed through rainfall and pre-plant irrigation. Both drip tape and hard hose drip tubing are suitable for use in our subsurface drip system. Maximum shallow ground water use for cotton was obtained when the crop was irrigated only after a leaf water potential (LWP) of −1.4 MPa was reached. Drip irrigation was controlled automatically with a maximum application frequency of twice daily. Furrow irrigation was controlled by the calendar.  相似文献   

5.
Deep percolation and nitrate leaching are important considerations in the design of sprinkler systems. Field experiments were therefore conducted to investigate the influence of nonuniformity of sprinkler irrigation on deep percolation and spatial distributions of nitrogen and crop yield during the growing season of winter wheat at an experiment station in Beijing, China. Three experimental plots of a sandy clay loam soil in the 0–40 cm depth interval and a loamy clay soil below 40 cm were irrigated with a sprinkler irrigation system that had a seasonal averaged Christiansen irrigation uniformity coefficient (CU) varying from 72 to 84%. Except for the fertilizer applied before planting, fertilizer was applied with the sprinkler irrigation system. The corresponding seasonal averaged CU for fertigation varied from 71 to 85%. Daily observation of matrix water potentials in the root zone showed that little deep percolation occurred. Consequently, the effect of sprinkler uniformity on deep percolation was minor during the irrigation season for the soil tested. Intensive gravimetric soil core samplings were conducted several times during the irrigation season in a grid of 5 m × 5 m for each plot to determine the spatial and temporal variation of NH4-N and NO3-N contents. Soil NH4-N and NO3-N exhibited high spatial variability in depth and time during the irrigation season with CU values ranging from 23 to 97% and the coefficient of variation ranging from 0.04 to 1.06. A higher uniformity of sprinkler fertigation produced a more uniform distribution of NH4-N, but the distribution of NO3-N was not related to fertigation. Rather it was related to the spatial variability of NO3-N before fertigation began. At harvest, the distribution of dry matter above ground, nitrogen uptake, and yield were measured and the results indicated that sprinkler fertigation uniformity had insignificant effects on the parameters mentioned above. Field experimental results obtained from this study suggest that sprinkler irrigation if properly managed can be used as an efficient and environment-friendly method of applying water and fertilizers.  相似文献   

6.
A field experiment was conducted in 1995 and 1996 to examine the effects of different irrigation methods on yields and Phytophthora root rot disease of chile plants (Capsicum annum New Mexico `6–4'). Three irrigation methods, daily drip, 3-day drip, and alternate row furrow irrigation, were applied to plots infested with P. capsici and uninfested plots. For both years, the drip irrigation (either daily or 3-day) created higher marketable green chile yields than the alternate row furrow irrigation (p < 0.05), and the yields between the daily and 3-day drip irrigation were statistically similar. The effect of irrigation on marketable combined yields was similar to that on green chile yields. In 1995, root rot disease incidence in the infested plots was significantly higher under alternate row furrow irrigation than for daily and 3-day drip irrigation. There was no disease development in the uninfested plots regardless of the irrigation method. The disease decreased green chile yield by 55% (p < 0.1), and combined yield (green + red chile) by 36% (p < 0.1) in 1995 compared to that in uninfested plots in alternate row furrow irrigation. In 1996, however, no disease occurred in any treatment. The results suggested that drip irrigation increases chile yield through providing either favorable soil moisture conditions or unfavorable conditions for Phytophthora propagation.  相似文献   

7.
Furrow irrigation events conducted under usual farmer management were analysed to determine the irrigation application efficiencies being attained, and the magnitude of the irrigation contribution to deep drainage under surface irrigated cotton in Queensland. Application efficiencies were shown to vary widely from 17 to 100% and on average were a low 48%. Losses to deep drainage were substantial, averaging 42.5 mm per irrigation. This has the potential for significant environmental harm and also represents an annual loss of up to 2500 m3/ha (2.5 Ml/ha) of water that could be beneficially used to grow more cotton. Simulations of each event using the simulation model SIRMOD illustrated simple ‘recipe’ strategies that would lead to gains in efficiency and reductions in the deep drainage losses. Additional simulations of selected events showed that further significant improvements in performance can be achieved by the application of more advanced irrigation management practices, involving in-field evaluation and optimisation of the flow rate and irrigation time to suit the individual soil conditions and furrow characteristics. Application efficiencies in the range 85–95% are achievable in all but the most adverse conditions. The dependency between deep drainage and irrigation management was demonstrated, confirming that substantial reductions in deep drainage are possible by ensuring that irrigation applications do not exceed the soil moisture deficit.  相似文献   

8.
Because of the spatial and temporal variabilities of the advance infiltration process, furrow irrigation investigations should not be limited to a single furrow irrigation event when using a modelling approach. The paper deals with the development and application of simulation of furrow irrigation practices (SOFIP), a model used to analyse furrow irrigation practices that take into account spatial and temporal variabilities of the advance infiltration process. SOFIP can be used to compare alternative furrow irrigation management strategies and find options that mitigate local deep-percolation risks while ensuring a crop yield level that is acceptable to the farmer. The model is comprised of three distinct modelling elements. The first element is RAIEOPT, a hydraulic model that predicts the advance infiltration process. Infiltration prediction in RAIEOPT depends on a soil moisture deficit parameter. PILOTE, a crop model, which is designed to simulate soil water balance and predict yield values, updates the soil moisture parameter. This parameter is an input of a parameter generator (PG), the third model component, which in turn provides RAIEOPT with the data required to simulate irrigation at the scale of an N-furrow set. The study of sources of variability and their impact on irrigation advance, based on field observations, allowed us to build a robust PG. Model applications show that irrigation practices must account for inter-furrow advance variability when optimising furrow irrigation systems. The impact of advance variability on deep percolation and crop yield losses depends on both climatic conditions and irrigation practices.  相似文献   

9.
A validated agro-hydrological model soil water atmosphere plant (SWAP) was applied to formulate guidelines for irrigation planning in cotton–wheat crop rotation using saline ground water as such and in alternation with canal water for sustainable crop production. Six ground water qualities (4, 6, 8, 10, 12 and 14 dS/m), four irrigation schedules with different irrigation depths (4, 6, 8 and 10  cm) and two soil types (sandy loam and loamy sand) were considered for each simulation. The impact of the each irrigation scenario on crop performance, and salinization/desalinisation processes occurring in the soil profile (0–2 m) was evaluated through Water Management Response Indicators (WMRIs). The criterion adopted for sustainable crop production was a minimum of pre-specified values of ETrel (≥0.75 and ≥0.65 for wheat and cotton, respectively) at the end of the 5th year of simulation corresponding to minimum deep percolation loss of applied water. The extended simulation study revealed that it was possible to use the saline water upto 14 dS/m alternatively with canal water for cotton–wheat rotation in both sandy loam and loamy sand soils. In all situations pre-sown irrigation must be accomplished with canal water (0.3–0.4 dS/m). Also when the quality of ground water deteriorates beyond 10 dS/m, it was suggested to use groundwater for post-sown irrigations alternately with canal water. Generally, percolation losses increased with the increase in level of salinity of ground water to account for leaching and thus maintain a favourable salt balance in the root zone to achieve pre-specified values of ETrel.  相似文献   

10.
The ridge and furrow rainfall harvesting (RFRH) system with mulches is being promoted to increase water availability for crops for higher and stable agricultural production in many areas of the Loess Plateau in northwest China. In the system, plastic-covered ridges serve as rainfall-harvesting zones and stone-, straw- or film-mulched furrows serve as planting zones. To adopt this system more effectively, a field study (using corn as an indicator crop) was conducted to determine the effects of different ridge:furrow ratios and supplemental irrigation on crop yield and water use efficiency (WUE) in the RFRH system with mulches during the growing seasons of 1998 and 1999.The results indicated that the ridge:furrow ratios had a significant effect on crop yield and yield components. The 120:60 cm ridge and furrow (120 cm wide ridge and 60 cm wide furrow) system increased yield by 27.9%, seed weight per head by 14.8%, seed number per head by 7.4% and 1000-seed weight by 4.7%, compared with the 60:60 cm ridge and furrow (60 cm wide ridge and 60 cm wide furrow) system. No differences in WUE were found between the two ratio systems. For corn and winter wheat, the optimum ridge:furrow ratio seems to be 1:1 in the 300-mm rainfall area, 1:2 in the 400-mm rainfall area and 1:4 in the 500-mm rainfall area. The optimum ridge:furrow ratio seems to be 1:3 for millet in the 300-mm rainfall area, although it is unnecessary to adopt RFRH practice in regions with more than 400 mm rainfall. The most effective ridge size for crop production seems 60 cm in the Loess Plateau. Implementing supplemental irrigation in the RFRH system is also a useful way to deal with the temporal problem of moisture deficits. In the case of corn, supplemental irrigation at its critical growth stage can increase both grain yield and WUE by 20%. The combination of in situ RFRH system with supplemental irrigation practice will make the RFRH system more attractive.  相似文献   

11.
In the Mesilla Valley of southern New Mexico, furrow irrigation is the primary source of water for growing onions. As the demand for water increases, there will be increasing competition for this limited resource. Water management will become an essential practice used by farmers. Irrigation efficiency (IE) is an important factor into improving water management but so is economic return. Therefore, our objectives were to determine the irrigation efficiency, irrigation water use efficiency (IWUE) and water use efficiency (WUE), under sprinkler, furrow, and drip irrigated onions for different yield potential levels and to determine the IE associated with the amount of water application for a sprinkler and drip irrigation systems that had the highest economic return.Maximum IE (100%) and economic return were obtained with a sprinkler system at New Mexico State University’s Agriculture Science Center at Farmington, NM. This IE compared with the 54–80% obtained with the sprinkler irrigation used by the farmers. The IEs obtained for onion fields irrigated with subsurface drip irrigation methods ranged from 45 to 77%. The 45% represents the nonstressed treatments, in which an extra amount of irrigation above the evapotranspiration (Et) requirement was applied to keep the base of the onion plates wet. The irrigation water that was not used for Et went to deep drainage water. The return on the investment cost to install a drip system operated at a IE of 45 was 29%. Operating the drip system at a IE of 79% resulted in a yield similar to surface irrigated onions and consequently, it was not economical to install a drip system. The IEs at the furrow-irrigated onion fields ranged from 79 to 82%. However, the IEs at the furrow-irrigated onion fields were high because farmers have limited water resources. Consequently, they used the concept of deficit irrigation to irrigate their onion crops, resulting in lower yields. The maximum IWUE (0.084 t ha−1 mm−1 of water applied) was obtained using the sprinkler system, in which water applied to the field was limited to the amount needed to replace the onions’ Et requirements. The maximum IWUE values for onions using the subsurface drip was 0.059 and 0.046 t ha−1 mm−1 of water applied for furrow-irrigated onions. The lower IWUE values obtained under subsurface drip and furrow irrigation systems compared with sprinkler irrigation was due to excessive irrigation under subsurface drip and higher evaporation rates from fields using furrow irrigation. The maximum WUE for onions was 0.009 t ha−1 mm−1 of Et. In addition, WUE values are reduced by allowing the onions to suffer from water stress.  相似文献   

12.
This study compares surge flow with conventional steady flow irrigation in 130–160 m field lengths in order to analyze the potential of the former for reducing deep percolation and tailwater runoff together with the improvement of irrigation efficiency. The field experiment comprises of four surge treatments with two inflow rates of 0.0498 and 0.12 m3/min (Q1 and Q2), and two cycle ratios of 0.33 and 0.50 (CR1 and CR2), respectively, with 30 min on-times, along with two steady flow treatments with the same inflow rates. Surge flow irrigation of the level furrows was successfully managed under the field conditions with decreases in the total water applications (2–22%) and the water intake (14–25%), except in the treatments of surge S11 (Q1 CR1) with 9% increase in the latter together with 21–38% decrease in the tailwater runoff and 19–70% decrease in the calculated deep percolation below the root zone of 1.20 m depending on inflow rates and cycle ratios of the permeable Harran soils. Surge flow reduced the water intake of a surface soil loosened by tillage by 13–23% as compared to continuous flow, thus manifesting an incomparable advantage to the level furrow systems.  相似文献   

13.
土壤入渗特性和田面糙率的变异性对沟灌性能的影响   总被引：2，自引：0，他引：2  
以杨凌区粘壤土和砂壤土区域进行的大田沟灌试验为基础,在假定各灌水沟内部土壤入渗特性和糙率均一的条件下,重点分析各灌水沟之间土壤入渗参数和田面糙率的不同组合对沟灌水流运动过程和灌水质量的影响,结果表明土壤入渗特性的变异性对沟灌水流推进过程和灌水质量指标影响较大,在模拟时必须充分考虑;而田面糙率的变异性对沟灌水流推进过程和灌水质量指标影响较小,可采用田块糙率均值代替各灌水沟的糙率。经实例验证,水流推进过程相对误差为7.28%,灌水效率、灌水均匀度和储水效率模拟值与实测值误差分别为5.74%、6.18%和4.07%,结果表明其模拟效果较好。  相似文献   

14.
Optimizing irrigation scheduling for winter wheat in the North China Plain   总被引：1，自引：0，他引：1  
In the North China Plain (NCP), more than 70% of irrigation water resources are used for winter wheat (Triticum aestivum L.). A crucial target of groundwater conservation and sustainable crop production is to develop water-saving agriculture, particularly for winter wheat. The purpose of this study was to optimize irrigation scheduling for high wheat yield and water use efficiency (WUE). Field experiments were conducted for three growing seasons at the Wuqiao Experiment Station of China Agriculture University. Eleven, four and six irrigation treatments, consisting of frequency of irrigation (zero to four times) and timing (at raising, jointing, booting, flowering and milking stage), were employed for 1994/95, 1995/96 and 1996/97 seasons, respectively. Available water content (AWC), rain events, soil water use (SWU), evapotranspiration (ET) and grain yield were recorded, and water use efficiency (WUE) and irrigation water use efficiency (IWUE) were calculated.The results showed that after a 75-mm pre-sowing irrigation, soil water content and AWC in the root zone of a 2-m soil profile during sowing were 31.1% (or 90.7% of field capacity) and 16.1%, respectively. Rainfall events were variable and showed a limited impact on AWC. The AWC decreased significantly with the growth of wheat. At the jointing stage no water deficits occurred for all treatments, at the flowering stage water deficits were found only in the rain-fed treatment, and at harvest all treatments had moderate to severe soil water deficits. The SWU in the 2-m soil profile was negatively related to the irrigation water volume, i.e. applying 75 mm irrigation reduced SWU by 28.2 mm. Regression analyses showed that relationships between ET and grain yield or WUE could be described by quadratic functions. Grain yield and WUE reached their maximum values of 7423 kg/ha and 1.645 kg/m3 at the ET rate of 509 and 382 mm, respectively. IWUE was negatively correlated with irrigated water volume. From the above results, three irrigation schedules: (1) pre-sowing irrigation only, (2) pre-sowing irrigation + irrigation at jointing or booting stage, and (3) pre-sowing irrigation + irrigations at jointing and flowering stages were identified and recommended for practical winter wheat production in the NCP.  相似文献   

15.
In this work we tested the influence of different solutions of a hydrophobic polymer named Guilspare®, applied to the soil surface to reduce soil evaporation, on the soil water status, soil temperature, crop performance and weed emergence. Two tests were carried out on a farm of the Guadalquivir river valley, southwest Spain, one with a maize crop and the other with bare soil. In the test with maize, we evaluated the effect of applying a solution of 2% v/v of Guilspare® in water, at the rate of 3 l m−2, on the crop performance and weed emergence. On both the treated and the untreated control plots, three rates of irrigation were applied, namely 100, 75 and 50% of the locally determined optimal irrigation depth to cover the crop needs for an optimum development and yield. For the case of 50% of the irrigation dose, the performance of the crop treated with the polymer (T50) was much better than that of the untreated control plot (C50). The crop height and green leaf area index for T50 were nearly as good as for the C100 control plants receiving 100% of the irrigation dose. The T50 crop was 73% of the yield of the treated and fully irrigated T100 crop, while the C50 yield was only 38% of the C100 yield. The treated crop reached the different phenological stages quicker than the untreated crop. The polymer was effective in reducing weed emergence. In the test with bare soil, 0.8% v/v of Guilspare® in water, at the rate of 1 l m−2, kept levels of water content in the soil as high as other solutions with greater amounts both of polymer and water. The average soil water content during the irrigation period in this lower treatment was 34 and 53% higher at depths of 0.15 and 0.25 m, respectively, than in the untreated plots. No influence of the polymer on soil temperature was observed. Results from additional measurements on weed emergence and hydraulic conductivity of the soil surface showed that the polymer was still effective 7 months after application. In fact, the hydraulic conductivity in the range near saturation was 44% greater in the treated plots than in the untreated ones, and the number of weeds was 27% lower.  相似文献   

16.
Frequent fertigation of crops is often advocated in the technical and popular literature, but there is limited evidence of the benefits of high-frequency fertigation. Field experiments were conducted on an Indo-American Hybrid var., Creole Red, of onion crop during three winter seasons of 1999–2000 through 2001–2002 in coarse-textured soil of Delhi under the semi-arid region of India. Three irrigation levels of 60, 80 and 100% of the crop evapotranspiration (ET) and four fertigation frequencies of daily, alternate day, weekly and monthly comprised the fertigation treatment. Analysis of soil samples indicated considerable influence of fertigation frequency on NO3-N distribution in soil profile. NO3-N in lower soil profiles (30.0–60.0 cm soil depth) was marginally affected in daily, alternate day and weekly fertigation. However, fluctuations of NO3-N content in 0.0–15.0, 15.0–30.0, 30.0–45.0 and 45.0–60.0 cm soil depth was more in monthly fertigation frequency. The level of soil NO3-N after the crop season shows that more NO3-N leached through the soil profile in monthly fertigation frequency. Amounts of irrigation water applied in three irrigation treatments proved to be too small to cause significant differences in the content of NO3-N leached beyond rooting depth of onion. Yield of onion was not significantly affected in daily, alternate day and weekly fertigation, though there was a trend of lower yields with monthly fertigation. The highest yield was recorded in daily fertigation (28.74 t ha−1) followed by alternate day fertigation (28.4 t ha−1). Lowest yield was recorded in monthly fertigation frequency (21.4 t ha−1). Application of 56.4 cm irrigation water and 3.4 kg ha−1 urea per fertigation (daily) resulted in highest yield of onion with less leaching of NO3-N.  相似文献   

17.
Water research studies in Saudi Arabia clearly showed sever depletion of groundwater. Therefore, the scientifically applied research program related to water saving and conservation in agriculture is essential, where agricultural activities account for more than 85% of the total water consumed. This study aims to investigate the effect of four irrigation levels, two irrigation methods and three clay deposits on water-use efficiency (WUE) of squash and the distributions of salts and roots in sandy calcareous soils. A field experiment was conducted at the college experimental station in 2002 and 2003. It consists of three clay deposits, three rates (CO = 0, C2 = 1.0 and C3 = 2.0%), four irrigation levels (T1 = 60, T2 = 80, T3 = 100 and T4 = 120% of Eto) using surface (IM1) and subsurface (IM2) drip irrigation.Results indicated that squash fruit yield was significantly increased with the increase in irrigation water level for each season. Generally, WUE values were increased as linearly with applied irrigation water and decreased at the highest irrigation level. Types of clay deposits significantly affected fruit yields compared with the control. The yield increase was 12.8, 8.35 and 6.4% for Khulays, Dhruma and Rawdat clay deposits, respectively. The differences between surface and subsurface drip on fruit yields and WUE were also significant. Results indicated that moisture content of subsurface-treated layer increased dramatically, while salts were accumulated at the surface and away from the emitters in subsurface drip irrigation. Intensive root proliferation is observed in the clay-amended subsurface layer compared with non-amended soil. The advantages of subsurface drip irrigation were related to the relative decrease in salt accumulation in the root zone area where the plant roots were active and water content was relatively higher.  相似文献   

18.
地面灌溉水流特性及水分利用率的数学模拟   总被引：10，自引：0，他引：10  
在内蒙古风沙区一种砂土和壤质砂土的春小麦生育期内进行了畦田规格和灌水技术要素对水流推进和消退过程、田间水利用系数、灌水效率及灌水均匀系数影响的田间试验。并用SRFR406软件对畦灌条件下的水流特性及水分利用率进行了数学模拟。结果表明,运用SRFR模型能较好地模拟地面灌溉的水流推进及消退过程,尤其是推进过程模拟求得的结果与实测结果基本吻合。畦田的微地形对灌水效率的影响较大,尤其是畦田尾部反坡对灌水效率及水流推进与消退都有较大影响。为提高灌水效率,应加强耕作管理,消除反坡。畦田规格对灌水效率也有一定的影响,从获得较高灌水效率的角度来说,以畦宽2～3m、畦长50～60m较为适宜。  相似文献   

19.
In general, cotton is irrigated by surface methods in Turkey although sprinkler and drip irrigation have been suggested as a means of supplying most types of crops with frequent and uniform applications of water, adaptable over a wide range of topographic and soil conditions. Recently, sprinkler irrigation systems have been introduced for cotton as a result of increased pressure to develop new irrigation technology suited to limited water supply as well as to specific topographic and soil conditions. In this study, the effects of three different irrigation methods (furrow, sprinkler and drip) on seed-cotton yield, shedding ratio and certain yield components are presented. The research was carried out in The Southeastern Anatolia Region (GAP) of Turkey from 1991 to 1994. The maximum cotton yields were 4380, 3630 and 3380 kg/ha for drip, furrow and sprinkler irrigation, respectively. Drip irrigation produced 21% more seed-cotton than the furrow method and 30% more than the sprinkler method. Water use efficiencies (WUE) proved to be 4.87, 3.87 and 2.36 kg/ha/mm for drip, furrow and sprinkler, respectively. Shedding ratios ranged from 50.8 to 59.0% (furrow), 52.9 to 64.8% (sprinkler), 50.8 to 56.8% (drip), depending on the amount of water applied. The shedding ratio for sprinkler irrigation was significantly higher than that of either furrow (P=0.10) or drip irrigation (P=0.05), resulting in lower seed-cotton yield for sprinkler irrigation. For all methods, a quadratic relationship was found between the amount of water applied and shedding ratios, with the least shedding occurring between 1000 and 1500 mm of water. Both limited and over-irrigation increased the shedding ratio for all methods. Accordingly, a lower boll number per plant and a lower seed-cotton yield were obtained from sprinkler-irrigated cotton; a significantly decreasing linear relationship between the shedding ratio and the total cotton yield and boll number per plant.  相似文献   

20.
Vast rainfed rice area (12 million ha) of eastern India remains fallow after rainy season rice due to lack of appropriate water and crop management strategies inspite of having favourable natural resources, human labourers and good market prospects. In this study, a short duration crop, maize, was tried as test crop with different levels of irrigation during winter season after rainy season rice to increase productivity and cropping intensity of rainfed rice area of the region. Maize hybrid of 120 days duration was grown with phenology based irrigation scheduling viz., one irrigation at early vegetative stage, one irrigation at tassel initiation, two irrigation at tassel initiation + grain filling, three irrigation at early vegetative + tassel initiation + grain filling and four irrigation at early vegetative + tassel initiation + silking + grain-filling stages. Study revealed that one irrigation at tassel initiation stage was more beneficial than that of at early vegetative stage. Upto three irrigation, water use efficiency (WUE) was increased linearly with increased number of irrigation. With four irrigations, the yield was higher, but WUE was lower than that of three irrigations, which might be due to increased water application resulted in increase crop water use without a corresponding increase of yield for the crop with four irrigations. The crop coefficients (Kc) at different stages of the crop were derived after computing actual water use using field water balance approach. The crop coefficients of 0.42–0.47, 0.90–0.97, 1.25–1.33, and 0.58–0.61 were derived at initial, development, mid and late season, respectively with three to four irrigation. Study showed that leaf area index (LAI) was significantly correlated with Kc values with the R2 values of 0.93. When LAI exceeded 3.0, the Kc value was 1. Study revealed that the Kc values for the development and mid season stage were slightly higher to that obtained by the procedure proposed by FAO, which might be due to local advection.  相似文献   

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