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1.
Summary Irrigation at 35 and 70 mm of pan evaporation applied during the pre and/or post early podfilling stages increased pod yield of Spanish peanuts (100 day maturity) three fold compared to a dryland crop. There was no difference in pod yield in crops receiving 12 compared to 6 irrigations. Soil water sampling immediately after irrigations on selected treatments revealed that infiltration of irrigation water was probably restricted to less than ca. 20 cm, a response which resulted in poor soil water replenishment and low irrigation efficiency (Fig. 3). Even though roots extracted soil water below the compaction layer which was at 20 cm severe crop water deficits had developed by the end of irrigation cycles during later but not early stages of growth. The dryland crop, which received no rainfall during the season, presumably extracted significant amounts of soil water at depths to and below 1.2 m (Fig. 3). Despite producing ca. 2.9 t ha-1 of total dry matter yield, pod yield was extremely low (0.5 t ha-1) arising from low pod numbers and high percentage of empty pods.This research was funded by the Australian Centre for International Agricultural Research (ACIAR-Project 8419) in collaboration with the Agency for Agricultural Research and Development (AARD).  相似文献   

2.
In the North China Plain (NCP), while irrigation using groundwater has maintained a high-level crop productivity of the wheat-maize double cropping systems, it has resulted in rapid depletion of groundwater table. For more efficient and sustainable utilization of the limited water resources, improved understanding of how crop productivity and water balance components respond to climate variations and irrigation is essential. This paper investigates such responses using a modelling approach. The farming systems model APSIM (Agricultural Production Systems Simulator) was first calibrated and validated using 3 years of experimental data. The validated model was then applied to simulate crop yield and field water balance of the wheat-maize rotation in the NCP. Simulated dryland crop yield ranged from 0 to 4.5 t ha−1 for wheat and 0 to 5.0 t ha−1 for maize. Increasing irrigation amount led to increased crop yield, but irrigation required to obtain maximum water productivity (WP) was much less than that required to obtain maximum crop yield. To meet crop water demand, a wide range of irrigation water supply would be needed due to the inter-annual climate variations. The range was simulated to be 140-420 mm for wheat, and 0-170 mm for maize. Such levels of irrigation applications could potentially lead to about 1.5 m year−1 decline in groundwater table when other sources of groundwater recharge were not considered. To achieve maximum WP, one, two and three irrigations (i.e., 70, 150 and 200 mm season−1) were recommended for wheat in wet, medium and dry seasons, respectively. For maize, one irrigation and two irrigations (i.e., 60 and 110 mm season−1) were recommended in medium and dry seasons, while no irrigation was needed in wet season.  相似文献   

3.
Shrinking water resources in northwest India calls for diversification from a rice–wheat cropping system to low-water-requiring crops and development of water-efficient technologies in Punjab state. Chickpea, because of its lower water demand (evapotranspiration) and irrigation requirement has been identified as a suitable alternate crop to wheat. Simulations, averaged over 18 years, using the CROPMAN model indicated that the yield of chickpea on coarse- to medium-textured soils was higher in a rice–chickpea cropping system compared with maize–chickpea and mung–chickpea systems because of increased availability of water. Yield response of chickpea to irrigation depended upon soil texture, the timings and number of irrigations. The optimum yield (2 t ha−1) on coarse- to medium-textured soils after rice can be obtained with one heavy pre-plant and two post-plant irrigations, i.e., one in mid-February and one in mid-March synchronizing irrigations with flowering and grain development stages. Grain yield with irrigation water followed a quadratic function and linear with evapotranspiration. Water use efficiency and evapotranspiration was curvilinear. Grain yield was significantly sensitive to water stress during the pod setting to grain development period irrespective of soil texture.  相似文献   

4.
In West Asia and North Africa (WANA) including northwest (NW) Iran irrigation is becoming increasingly available and investigation of the effect of limited irrigation (LI) is a research need. Only a few seasons of successful experimentation exist with LI effects. Thus, the objective of this simulation study was to examine potential long-term benefits of limited irrigation in NW Iran in terms of grain yield. To do this, a simple, mechanistic chickpea (Cicer arietinum L.) model and 16 years of weather data of Maragheh (NW Iran) were used. Three LI systems with one, two and three irrigations and each with three plant population densities (25, 38 and 50 plants m−2) were simulated. Results showed chickpea crop experiences terminal drought stress that is started at a time between flowering and beginning seed growth (BSG). This terminal drought stress severely reduces grain yield by 67%, from 2766 kg ha−1 under full-irrigated conditions to 909 kg ha−1 under rainfed conditions. Grain yield was significantly increased with LI compared to rainfed conditions. Grain yields were reached to 60, 75 and 90% of grain yield simulated under full-irrigated (generally requires five irrigations) conditions. In LI with one irrigation its application at BSG, and in LI with two and three irrigations, application of first irrigation at flowering and application of one or two other irrigations when fraction of transpirable soil water dropped to 0.5 in the root zone resulted in higher grain yield. Water use efficiency was, also, increased with LI by 28, 39 and 52% for one, two and three irrigations, respectively. In LI systems with two and three irrigations it was required to a higher plant density (38 or 50 plants m−2) to capture and to use applied water more efficiently.  相似文献   

5.
Agricultural growers need investment and cost guidelines for drip irrigation to evaluate the economics of getting crops into production as quickly as possible and to minimise economic losses from drought during the productive life of an olive orchard. The benefits of irrigation may include; better olive survival, earlier crop production, greater yields, efficient nutrient distribution, less plant stress, reduced yield variability and improved crop quality.This research was conducted to help olive growers make decisions regarding investments in drip irrigation systems. This analysis was aimed at the farm business level to provide an economic rationale for investing in drip irrigation systems.The net present value (NPV) criterion was used to determine the discounted break-even investment results from published responses to drip irrigation systems. Growers with typical drip irrigation systems can expect investments of US$ 2244 ha−1 with 1.6 ha blocks of olives. Analysis of survey findings indicate that net present value was US$ 3464 ha−1 after an initial investment of US$ 2244 ha−1.  相似文献   

6.
When subsurface irrigation sources are lacking in humid and subhumid regions, high yearly precipitation may allow for storage of surface water in farm ponds and lakes for irrigation. Irrigation at selected growth stages may avoid critical stress for crops with some drought tolerance, such as grain sorghum [Sorghum bicolor (L.) Moench]. Because grain sorghum is responsive to N, injecting fertilizer N through the irrigation system also may improve production. The objective of this study was to determine the effect of timing of limited-amount irrigation and N fertigation on grain sorghum yield; yield components; grain N content; and N uptake at the 9-leaf, boot, and soft dough stages. The experiment was conducted from 1984 to 1986 on a Parsons silt loam (fine, mixed, thermic, Mollic Albaqualf). The experiment was designed as a 6 × 2 factorial plus two reference treatments. Six timings for irrigation were targeted at the 9-leaf (9L), boot (B), soft dough (SD), 9L-B, 9L-SD, and B-SD growth stages. N application systems were either 112 kg N ha–1 surface-banded preplant or 56 kg N ha-1 preplant and 56 kg N ha–1 injected through the irrigation at a rate of 28 kg N ha–1 per 2.5 cm of irrigation. Two reference treatments included were one receiving N but no irrigation and one receiving neither N nor irrigation. In 1984, irrigation generally increased grain sorghum yield by nearly 1 Mg ha–1. However, yield was not affected by selection of irrigation timing, N application method, or the interaction of the two factors. This was partly because early irrigations increased kernels/head, whereas later irrigations increased kernel weight. Above average rainfall during the growing season, especially just prior to the 9-leaf, boot, and soft dough growth stages, resulted in no irrigations in 1985. In 1986, yield was increased by early (9-leaf) irrigations as compared to soft dough irrigations. Early irrigations resulted in higher kernels/head; however, rainfall after the soft dough irrigation may have masked any treatment effect on kernel weight. As in 1984, N application method did not affect grain sorghum yields, even though yield was reduced to less than 3 Mg ha–1 with no N nor irrigation. In both 1984 and 1986, N uptake at succeeding growth stages appeared to respond to irrigations made at previous growth stages. Injecting half of the fertilizer N through the irrigation system did not affect N uptake compared to applying all N preplant. The lack of response to fertigation may be related to the low leaching potential of the soil used in this study.Contribution No. 92-606-J, Kansas Agricultural Experiment Station  相似文献   

7.
A study was carried out in Malawi to compare agronomic and socio-economic aspects of different water management practices for two advanced bean lines. Four irrigation technologies and one control were studied in Chingale Area Development Program in Zomba District in southern Malawi. The technologies encompassed motorized pumps (MP), treadle pumps (TP), water cans, gravity-fed surface irrigation (GR) and a non-irrigated practice that used residual moisture. The study found that technologies that used <2 labour hours m?3 were appropriate for such small-scale irrigation systems. The aggregated bean production labour cost and labourday thresholds were $893 ha?1 and 2,978 LD ha?1, respectively. An irrigation supply in the range of 7,000–10,000 m3 ha?1 for the TP, MP and GR would be adequate. Assuming 20 irrigations season?1, 400–600 m3 irrigation?1 would be adequate, supplying 40–60 mm every 5–7 days. The study found that poor small-scale farmers in Malawi, particularly those using MPs, need fuel subsidies in order to offset operational costs. Basing on the findings in the study, we recommend further research on several bean lines in different agro-ecologies of Malawi using technologies that showed high yields, low labour efficiency and high water use productivity.  相似文献   

8.
Soil moisture availability is the main limiting factor for growing second crops in rainfed rice fallows of eastern India. Only rainfed rice is grown with traditional practices during the rainy season (June–October) with large areas (13 m ha−1) remaining fallow during the subsequent dry season (November–March) inspite of annual rainfall of the order 1000–2000 mm. In this study an attempt was made to improve productivity of rainfed rice during rainy season and to grow second crops in rice fallow during dry (winter) season with supplemental irrigation from harvested rainwater. Rice was grown as first crop with improved as well as traditional farmers’ management practices to compare the productivity between these two treatments. Study revealed that 87.1–95.6% higher yield of rice was obtained with improved management over farmers’ practices. Five crops viz., maize, groundnut, sunflower, wheat and potato were grown in rice fallow during dry (winter) season with two, three and four supplemental irrigations and improved management. Sufficient amount of excess rainwater (runoff) was available (381 mm at 75% probability level) to store and recycle for supplementary irrigation to second crops grown after rice. Study revealed that supplemental irrigation had significant effect (P < 0.001) on grain yield of dry season crops and with two irrigation mean yields of 1845, 785, 905, 1420, 8050 kg ha−1 were obtained with maize (grain), groundnut, sunflower, wheat and potato (tuber), respectively. With four irrigations 214, 89, 78, 81, 54% yield was enhanced over two irrigations in respective five crops. Water use efficiency (WUE) of 13.8, 3.35, 3.39, 5.85 and 28.7 kg ha−1 was obtained in maize, groundnut, sunflower, wheat, potato (tuber), respectively with four irrigations. The different plant growth parameters like maximum above ground biomass, leaf area index and root length were also recorded with different levels of supplemental irrigation. The study amply revealed that there was scope to improve productivity of rainfed rice during rainy season and to grow another profitable crops during winter/dry season in rice fallow with supplemental irrigation from harvested rainwater of rainy season.  相似文献   

9.
The DSSAT-CSM-CERES-Wheat V4.0 model was calibrated for yield and irrigation scheduling of wheat with 2004–2005 data and validated with 13 independent data sets from experiments conducted during 2002–2006 at the Punjab Agricultural University (PAU) farm, Ludhiana, and in a farmer's field near PAU at Phillaur, Punjab, India. Subsequently, the validated model was used to estimate long-term mean and variability of potential yield (Yp), drainage, runoff, evapo-transpiration (ET), crop water productivity (CWP), and irrigation water productivity (IWP) of wheat cv. PBW343 using 36 years (1970–1971 to 2005–2006) of historical weather data from Ludhiana. Seven sowing dates in fortnightly intervals, ranging from early October to early January, and three irrigation scheduling methods [soil water deficit (SWD)-based, growth stage-based, and ET-based] were evaluated. For the SWD-based scheduling, irrigation management depth was set to 75 cm with irrigation scheduled when SWD reached 50% to replace 100% of the deficit. For growth stage-based scheduling, irrigation was applied either only once at one of the key growth stages [crown root initiation (CRI), booting, flowering, and grain filling], twice (two stages in various combinations), thrice (three stages in various combinations), or four times (all four stages). For ET-driven irrigation, irrigations were scheduled based on cumulative net ETo (ETo-rain) since the previous irrigation, for a range of net ETo (25, 75, 125, 150, and 175 mm). Five main irrigation schedules (SWD-based, ET-driven with irrigation applied after accumulation of either 75 or 125 mm of ETo, i.e., ET75 or ET125, and growth stage-based with irrigation applied at CRI plus booting, or at CRI plus booting plus flowering stage) were chosen for detailed analysis of yield, water balance, and CWP and IWP. Nitrogen was non-limiting in all the simulations.Mean Yp across 36 years ranged from 5.2 t ha−1 (10 October sowing) to 6.4 t ha−1 (10 November sowing), with yield variations due to seasonal weather greater than variations across sowing dates. Yields under different irrigation scheduling, CWP and IWP were highest for 10 November sowing. Yields and CWP were higher for SWD and ET75-based irrigations on both soils, but IWP was higher for ET75-based irrigation on sandy loam and for ET150-based irrigation on loam. Simulation results suggest that yields, CWP, and IWP of PBW343 would be highest for sowing between late October and mid-November in the Indian Punjab. It is recommended that sowing be done within this planting period and that irrigation be applied based on the atmospheric demand and soil water status and not on the growth stage. Despite the potential limitations recognised with simulation results, we can conclude that DSSAT-CSM-CERES-Wheat V4.0 is a useful decision support system to help farmers to optimally schedule and manage irrigation in wheat grown in coarse-textured soils under declining groundwater table situations of the Indian Punjab. Further, the validated model and the simulation results can also be extrapolated to other areas with similar climatic and soil environments in Asia where crop, soil, weather, and management data are available.  相似文献   

10.
Estimates of the effects of alternative discrete irrigation water scheduling options on consumptive use or evapotranspiration and on crop yield are developed for a northeastern Colorado case study. The analysis proceeds from the premise that farmers, rather than considering irrigation water as a continuously variable input, tend to treat irrigations as discrete events, and make scheduling decisions as choices among numbers of irrigations of approximately equal volume. The van Genuchten-Hanks model is employed to develop a transient-state water-crop production function model. Results for two crops – corn grain and edible dry beans – are presented here. Findings are that the effect of the number of irrigations on evapotranspiration and yield per hectare varies widely, depending upon the timing of applications. When farmers can choose the optimal timing of irrigations, a reduced number of irrigations has a relatively limited adverse effect on crop production until irrigations are reduced to less than four per season. However, there are many situations in which an inability to apply water can result in a very large reduction from potential maximum yield, particularly if water is withheld early in the season and/or during the rapid growth period of the crops. In many contexts of irrigation water management, water policy analysts will wish to consider the more realistic discrete-input simulation model for policy evaluation. Received: 1 November 1996  相似文献   

11.
Research on crop response to deficit irrigation is important to reduce agricultural water use in areas where water is a limited resource. Two field experiments were conducted on a loam soil in northeast Spain to characterize the response of maize (Zea mays L.) to deficit irrigation under surface irrigation. The growing season was divided into three phases: vegetative, flowering and grain filling. The irrigation treatments consisted of all possible combinations of full irrigation or limited irrigation in the three phases. Limited irrigation was applied by increasing the interval between irrigations. Soil water status, crop growth, above-ground biomass, yield and its components were measured. Results showed that flowering was the most sensitive stage to water deficit, with reductions in biomass, yield and harvest index. Average grain yield of treatments with deficit irrigation around flowering (691 g m−2) was significantly lower than that of the well-irrigated treatments (1069 g m(2). Yield reduction was mainly due to a lower number of grains per square metre. Deficit irrigation or higher interval between irrigations during the grain filling phase did not significantly affect crop growth and yield. It was possible to maintain relatively high yields in maize if small water deficits caused by increasing the interval between irrigations were limited to periods other than the flowering stage. Irrigation water use efficiency (IWUE) was higher in treatments fully irrigated around flowering.  相似文献   

12.
A field study was conducted at North Platte, Nebraska in 2007–2009, imposing eight irrigation treatments, ranging from dryland to fully irrigated. Four of the eight treatments allowed for various degrees of water stress only after tasseling and silking. In 2007, corn yield ranged from 8.9 Mg ha?1 with a season total of 41 mm of irrigation water to 11.5 Mg ha?1 for the fully irrigated treatment (264 mm of irrigation water). The treatment with the greatest reduction in irrigation water after tasseling and silking (158 mm) had a mean yield of 10.9 Mg ha?1, only 0.6 Mg ha?1 less than the fully irrigated treatment. In 2009, yields ranged from 12.6 to 13.5 Mg ha?1. There were no significant yield differences between the irrigation treatments for several possible reasons: more in-season precipitation and cooler weather required less irrigation water; much of the irrigation water was applied after the most water-stress sensitive stages of tasseling and silking; and lower atmospheric demand allowed for soil water contents well below 50 % management allowed depletion (MAD) not to cause any yield losses.  相似文献   

13.
Camelina sativa (L.) Crantz is a promising, biodiesel-producing oilseed that could potentially be implemented as a low-input alternative crop for production in the arid southwestern USA. However, little is known about camelina’s water use, irrigation management, and agronomic characteristics in this arid environment. Camelina experiments were conducted for 2 years (January to May in 2008 and 2010) in Maricopa, Arizona, to evaluate the effectiveness of previously developed heat unit and remote sensing basal crop coefficient (K cb ) methods for predicting camelina crop evapotranspiration (ET) and irrigation scheduling. Besides K cb methods, additional treatment factors included two different irrigation scheduling soil water depletion (SWD) levels (45 and 65 %) and two levels of seasonal N applications within a randomized complete block design with 4 blocks. Soil water content measurements taken in all treatment plots and applied in soil water balance calculations were used to evaluate the predicted ET. The heat-unit K cb method was updated and validated during the second experiment to predict ET to within 12–13 % of the ET calculated by the soil water balance. The remote sensing K cb method predicted ET within 7–10 % of the soil water balance. Seasonal ET from the soil water balance was significantly greater for the remote sensing than heat-unit K cb method and significantly greater for the 45 than 65 % SWD level. However, final seed yield means, which varied from 1,500 to 1,640 kg ha?1 for treatments, were not significantly different between treatments or years. Seed oil contents averaged 45 % in both years. Seed yield was found to be linearly related to seasonal ET with maximum yield occurring at about 470–490 mm of seasonal ET. Differences in camelina seed yields due to seasonal N applications (69–144 kg N ha?1 over the 2 years) were not significant. Further investigations are needed to characterize camelina yield response over a wider range of irrigation and N inputs.  相似文献   

14.
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   

15.
Water use efficiency and yield of barley were determined in a field experiment using different irrigation waters with and without nitrogen fertilizer on a sandy to loamy sand soil during 1994–1995 and 1995–1996. Depending upon different fertilizer treatments, the overall mean crop yield ranges for two crop seasons were: greenmatter from 19.48–55.0 Mg ha−1 (well water) and 21.92–66.5 Mg ha−1 (aquaculture effluent); drymatter from 6.86–20.69 Mg ha−1 (well water) and 7.87–20.90 Mg ha−1 (aquaculture effluent); biomass from 4.12–21.31 Mg ha−1 (well water) and 8.10–19.94 Mg ha−1 (aquaculture effluent) and grain yield from 2.12–5.50 Mg ha−1 (well water) and 3.25–7.25 Mg ha−1 (aquaculture effluent). The WUE for grain yield was 3.37–8.74 kg ha−1 mm−1 (well water) and 5.17–11.53 kg ha−1 mm−1 (aquaculture effluent). The WUE for total biomass ranged between 6.55–33.88 kg−1 ha−1 mm−1 (well water) and 12.88–31.70 kg ha−1 mm−1 (aquaculture effluent). The WUE for drymatter was 10.91–32.90 kg ha−1 mm−1 (well water) and 12.51–33.22 kg ha−1 mm−1 (aquaculture effluent). It was found that grain yield and WUE obtained in T-4 and T-5 irrigated with well water and receiving 75 and 100% nitrogen requirements were comparable with T-4 and T-5 irrigated with aquaculture effluent and receiving 0 and 25% nitrogen requirements. In conclusion, application of 100 to 150 kg N ha−1 for well water and up to 50 kg N ha−1 for aquaculture effluent irrigation containing 40 Mg N l−1 would be sufficient to obtain optimum grain yield and higher WUE of barley in Saudi Arabia.  相似文献   

16.
Camelina sativa (L.) Crantz is an oilseed crop touted as being suitable for production in the arid southwestern USA. However, because any significant development of the crop has been limited to cooler, rain-fed climate-areas, information and guidance for managing irrigated-camelina are lacking. This study measured the crop water use of a November-through-April camelina crop in Arizona using frequent measurements of soil water contents. The crop was grown under surface irrigation using five treatment levels of soil water depletion. The seed yields of treatments averaged 1,142 kg ha−1 (8.0% seed moisture) and were generally comparable with camelina yields reported in other parts of the USA. Varying total irrigation water amounts to treatments (295–330 mm) did not significantly affect yield, whereas total crop evapotranspiration (ETc) was increased for the most frequently irrigated treatment. However, total ETc for the camelina treatments (332–371 mm) was markedly less than that typically needed by grain and vegetable crops (600–655 mm), which are commonly grown during the same timeframe in Arizona. The camelina water-use data were used to develop crop coefficients based on days past planting, growing degree days, and canopy spectral reflectance. The crop coefficient curves, along with information presented on camelina soil water depletion and root zone water extraction characteristics will provide camelina growers in arid regions with practical tools for managing irrigations.  相似文献   

17.
Irrigation scheduling results from the irrigator's integration of meteorological, environmental and crop information. In this paper, the irrigation scheduling patterns of a group of irrigators in the Candasnos Water Users Association (WUA), located in north-eastern Spain, were analysed. Scheduling sprinkler and drip irrigation in this WUA shows additional complications due to the sharing of a collective pressurized irrigation network and to the need to file water orders two days in advance of its foreseen use. The database created by a remote surveillance and control system was mined to obtain the time evolution of hydrant operation time during the 2004–2008 irrigation seasons. Records were selected for clearly identified crops and irrigation systems, and for verified water allocations. Hydrant operation showed a relationship with meteorology (precipitation, wind speed, relative humidity and air temperature), although this relationship was often not evident when hydrants were individually analysed. Statistical analyses were run to classify irrigator's scheduling practices, leading to the establishment of ten different groups. The adopted classification criteria included the average number of weekly irrigations, the SD of the number of weekly irrigations and the modal range of the irrigation starting time. The irrigation pattern was determined by the irrigator (56%), the irrigation system (33%), and the crop (11%). Only in a fraction of the cases (22%) the time change in the scheduling pattern responded to a clear time trend; in 39% of the cases, changes in time appeared random. Further, 45% of the irrigators used the same irrigation pattern in at least half of their hydrant-years, independently of the crop. Only 14% of the irrigators applied different irrigation scheduling patterns to different crops. Our results suggest that irrigators do not find value or do not have the capacity to develop irrigation patterns more consistent and adapted to the local environment, the crops and the irrigation systems.  相似文献   

18.
Summary The effect of the soil water potential on pod yield of snap beans grown with a series of irrigation frequencies was studied over two seasons. The treatments were to furrow-irrigate either weekly or fortnightly during the preflowering period, and each treatment then received weekly or fortnightly irrigations to harvest. These treatments were compared with trickle irrigation applied daily in the first season and every second day in the second season. The irrigation frequencies during the pre-flowering period did not influence the pod yield. However, in the second season plants given the trickle irrigation treatment produced more early flowers and set pods earlier than those in the other treatments. Consequently the pods were harvested three days earlier from plants on this treatment.Pod yield was determined by the irrigation treatments applied after flowering. The highest yield was similar in each season (16.7 t ha–1) and was produced under trickle irrigation. Fortnightly irrigations during the pod-fill phase reduced yield by 56% in the first season and 41% in the second season when compared with trickle irrigation. The pod yield was reduced by 0.5 t ha–1 each day the soil water potential at 30 cm depth was less than –50 kPa. This relationship accounted for about 77% of the variation in pod yield.  相似文献   

19.
With the availability of irrigation water, supplemental irrigation in winter-grown crops, such as lentil, wheat, and barley, has been intensely practiced to prevent crop yield losses due to the incidence of intermittent drought stress. In the crop growing seasons of 2006-2007 and 2008-2009, a study was conducted to determine the effect of supplemental irrigations on Canola (Brassica napus L. cv. Elvis F1) under the semiarid climatic conditions of the Harran plain, Sanliurfa, Turkey. A sprinkler irrigation system was used to irrigate the study plots. The irrigation treatments included 0.0, 0.25, 0.50, 0.75, and 1.0 (full irrigation) of Class-A pan evaporation amounts. The full irrigation treatment during both years consisted of 250 and 225 mm, respectively. In turn, crop water use values during the same years and treatments were 462 and 449 mm. In general, plant height and 1000 seed weight ranged from 140 to 165 cm and from 2.5 to 3.3 g, respectively, and these variables significantly differed among irrigation treatments (p < 0.05). Crop yield and above ground biomass measurements were affected by irrigation treatments and varied from 1094 to 3943 kg ha−1 and from 6746 to 18,311 kg ha−1, respectively (p < 0.05). Similarly, harvest index values were affected (p < 0.05) and ranged from 0.16 to 0.23 on average. The water use efficiency obtained in the different treatments indicated a strong positive relationship between crop yield and irrigation. Overall, our results indicate that supplemental irrigation substantially increased canola yield; however, for an optimum yield, full irrigation is suggested.  相似文献   

20.
The worldwide need to improve water use efficiency within irrigated agriculture has been recognised in response to environmental concerns and conflicts in resource use. Within the Australian cotton industry, the imperative to reduce water use and optimise irrigation management through the understanding of risk, using information generated by computerised decision aids was identified and subsequently developed into the HydroLOGIC irrigation management software. This paper summarises the attributes of the HydroLOGIC irrigation management software, with particular emphasis on functionality and its application to irrigation decisions within the Australian cotton industry. The software development process is documented to provide direction for future software application initiatives, with particular emphasis on a process of user feedback, evaluation and support requirements providing direction to software development. On-farm experiments throughout the development period allowed the validation of internal software logic, irrigator decision processes, and the OZCOT cotton growth model. The software demonstrated the ability to improve yield and water use efficiency by optimising strategic and tactical irrigation decisions in the Australian furrow irrigation cotton production system. In 7 of the 11 on-farm experiments conducted, the use of HydroLOGIC helped improve overall field water use efficiency by optimising the timing of irrigation events or by indicating further irrigations would not provide yield or maturity benefits. The paper also presents useful insights into the development of software targeted for irrigation utilising in-field measurements of soil water, crop growth and a crop growth simulation model.  相似文献   

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