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1.
The effect of saline irrigation was investigated on germination and growth parameters of six barley (Hordeum vulgare L.) cultivars in a pot experiment. The crop germination decreased between 24–35% with irrigation water having EC of 9.26 dS m−1, 28–47% with water EC of 13.4 dS m−1 and 30–53% with water EC of 16.28 dS m−1 among various cultivars. The sequence of reduction in germination was Hassawi > Gusto > Madini > M. Khariji > Qassimi. Plant height and total number of plant tillers decreased significantly with increasing irrigation-water salinity. Plant height ranged between 39.43 cm (Qassimi cultivar) with water EC of 3.00 dS m−1 to 1.97 cm (Gusto) with water EC of 16.28 dS m−1 whereas the range for total number of plant tillers per pot was 77.00 (Qassimi) with irrigation EC of 3.00 dS m−1 to 9.67 (Gusto) with irrigation EC of 16.28 dS m−1. The trend of reduction in plant height for different cultivars was Gusto > Qassimi > Hassawi > Madini > M. Khariji whereas for plant tillers, the sequence was Gusto < Hassawi < M. Khariji < Qassimi < Madini. Greenmatter and drymatter yield decreased significantly with increasing irrigation water salinity. The greenmatter yield ranged between 138.67 g per pot (Madini) with water EC of 3.00 dS m−1 to 11.40 g per pot (Gusto) with water EC of 16.28 dS m−1. A similar trend was found for drymatter yield. The trend of reduction in yield among various cultivars (both greenmatter and drymatter) was Gusto > Hassawi > M. Khariji > Qassimi > Madini. Overall sequence of salt tolerance for different barley cultivars was Madini > Qassimi > M. Khariji > Hassawi > Gusto. A comparison of cultivars indicated that irrigation waters with EC 13.40 dS m−1 and above reduced crop germination and greenmatter production to a significant level. In conclusion, there exists a lot of potential for a reasonable production of barley as forage crop with irrigation water having salinity up to 9.26 dS m−1 provided 15% extra water above crop-water requirement is applied as leaching requirements to control soil salinity.  相似文献   

2.
A simulation model has been prepared for assessing water quality to judge its suitability for irrigation. When water is classified as poor quality water (saline/sodic/saline-sodic) utilizing standard norms for Indian agro-climatic conditions, the model determines the potential of the water for direct application. Further, it also evaluates management strategies based on conjunctive use of fresh and saline waters. For this purpose, the model requires water quality data, crop data, soil data and rules established in the expert system rule-base. Data are compiled in data files which can be updated. For conjunctive use of saline and fresh waters, an irrigation scheduling sub-model has been modified to include a soil salinization-desalinization module based on layer-wise equilibrium theory. The module was independently tested using field data. The model SWAM has been successfully tested using data from a number of field experiments. Sodic waters of 16.2 meq l−1 residual sodium carbonate would require 2.73 t ha−1 of gypsum for each 20 cm of water applied to the soil. Field observations usually attest to this requirement. Likewise, saline water of 16 dS m−1, when applied to a wheat crop in conjunction with fresh water of 0.5 dS m−1, would yield optimally in case two saline water irrigations are followed by one fresh water irrigation in a normal rainfall year with an initial soil salinity of 2.98 dS m−1. Some more useful data sets are analyzed and compared with results from field experiments. In our opinion, the model which is based upon recent guidelines can be applied to the classification of waters and their management. The minor changes necessary to apply the model to other conditions can be easily carried out.  相似文献   

3.
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   

4.
Yield and nitrogen use efficiency (NUE) of wheat was investigated under field conditions using two types of irrigation waters with and without nitrogen on a sandy-loam to loamy-sand soil during 1992–1993 and 1993–1994. Depending upon different nitrogen treatments, the mean crop yield ranges in 1992–1993 were: grain yield 6.19–6.87 Mg ha− and biomass 15.41–16.34 Mg ha−1 receiving treated effluent. The mean crop yield ranges in 1993–1994 were: grain yield 0.46–3.23 Mg ha−1 (well water) and 5.20–6.54 Mg ha−1 (treated effluent); and biomass 1.84–10.80 Mg ha−1 (well water), and 16.00–19.29 Mg ha−1 (treated effluent). The NUE for grain yield in 1992–1993 was between 16.70–50.23 kg kg−1 N (well water) and 20.65–91.56 kg kg−1 N (treated effluent). Whereas the NUE in 1993-94, varied between 10.49–32.13 kg grain kg−1 N (well water) and 21.30–72.93 kg grain kg−1 N (treated effluent). The NUE for total biomass in 1992–1993 varied between 46.54–130.32 kg kg−1 N (well water) and 53.66–158.77 kg kg−1 N (treated effluent). Similarly, the NUE in 1993–1994 varied between 35.99–102.1 kg biomass kg−1 N (well water) and 59.27–161.89 kg biomass kg−1 N (treated effluent). A significant decrease in NUE was observed with increasing nitrogen application both for grain and biomass production. In conclusion, a higher grain yield and NUE of wheat crop can be achieved with low application rates of nitrogen if the crop is irrigated with treated effluent containing nitrogen in the range of 20 mg L−1 and above.  相似文献   

5.
In arid and semi-arid regions, effluent from sub-surface drainage systems is often saline and during the dry season its disposal poses an environmental problem. A field experiment was conducted from 1989 to 1992 using saline drainage water (EC=10.5–15.0 dS/m) together with fresh canal water (EC=0.4 dS/m) for irrigation during the dry winter season. The aim was to find if crop production would still be feasible and soil salinity would not be increased unacceptably by this practice. The experimental crops were a winter crop, wheat, and pearl-millet and sorghum, the rainy season crops, grown on a sandy loam soil. All crops were given a pre-plant irrigation with fresh canal water. Subsequently, the wheat crop was irrigated four times with different sequences of saline drainage water and canal water. The rainy season crops received no further irrigation as they were rainfed. Taking the wheat yield obtained with fresh canal water as the potential value (100%), the mean relative yield of wheat irrigated with only saline drainage water was 74%. Substitution of canal water at first post-plant irrigation and applying thereafter only saline drainage water, increased the yield to 84%. Cyclic irrigations with canal and drainage water in different treatments resulted in yields of 88% to 94% of the potential. Pearl-millet and sorghum yields decreased significantly where 3 or 4 post-plant irrigations were applied with saline drainage water to previous wheat crop, but cyclic irrigations did not cause yield reduction. The high salinity and sodicity of the drainage water increased the soil salinity and sodicity in the soil profile during the winter season, but these hazards were eliminated by the sub-surface drainage system during the ensuing monsoon periods. The results obtained provide a promising option for the use of poor quality drainage water in conjunction with fresh canal water without undue yield reduction and soil degradation. This will save the scarce canal water, reduce the drainage water disposal needs and associated environmental problems.  相似文献   

6.
A field experiment was carried out to determine the effect of irrigation and nitrogen on two cultivars of oilseed crops (Brassica napus L. cv. canola and Brassica campestris L. cv rapeseed) on a sandy-clay-loam soil during 1993–1994. The mean plant height ranges for canola were: 1.20–1.40 m (well water) and 1.40–1.57 m (aquaculture effluent); and for rapeseed from 1.281.52 m (well water) and 1.41–1.58 m (aquaculture effluent) in different fertilizer treatments. Mean biomass yield for canola ranged between 14.60–17.84 Mg ha−1 (well water) and 14.09–19.51 Mg ha−1 (aquaculture effluent); and for rapeseed from 16.67–19.51 Mg ha−1 (well water) and 12.70–20.74 Mg ha−1 (aquaculture effluent). The mean seed yield for canola varied from 2.65–3.44 Mg ha−1 (well water) and 3.02–3.74 Mg ha−1 (aquaculture effluent): and for rapeseed from 2.73–3.26 Mg ha−1 (well water) and from 2.62–3.29 Mg ha−1 (aquaculture effluent). The mean straw yield ranges for canola were: 12.01–14.39 Mg ha−1 (well water) and 13.65–15.93 Mg ha−1 (aquaculture effluent); and for rapeseed from 11.67–13.28 Mg ha−1 (well water) and 9.83–17.45 Mg ha−1 (aquaculture effluent). The mean oil contents for canola were 30.92–36.12% (aquaculture effluent) and 32.47–35.78% (well water); and for rapeseed from 30.15–34.53% (aquaculture effluent) and 33.50–35.96% (aquaculture effluent). The mean protein contents of straw were 5.42–6.44% (canola) and 3.78–4.37% (rapeseed) in different fertilizer treatments. Application of 175 kg N ha−1 with 50 kg P ha−1 showed significant effect on crop yield under both types of irrigation water. Based on the results of this study, it appears that cultivars of rapeseed recently introduced from Canada have an excellent potential as oilseed crops in Saudi Arabia.  相似文献   

7.
The analysis of irrigation and drainage management and their effects on the loading of salts is important for the control of on-site and off-site salinity effects of irrigated agriculture in semi-arid areas. We evaluated the irrigation management and performed the hydrosalinity balance in the D-XI hydrological basin of the Monegros II system (Aragón, Spain) by measuring or estimating the volume, salt concentration and salt mass in the water inputs (irrigation, precipitation and Canal seepage) and outputs (evapotranspiration and drainage) during the period June 1997–September 1998. This area is irrigated by solid-set sprinklers and center pivots, and corn and alfalfa account for 90% of the 470 ha irrigated land. The soils are low in salts (only 10% of the irrigated land is salt-affected), but shallow (<2 m) and impervious lutites high in salts (average ECe=10.8 dS m−1) and sodium (average SARe=20 (meq l−1)0.5) are present in about 30% of the study area.The global irrigation efficiency was high (Seasonal Irrigation Performance Index=92%), although the precipitation events were not sufficiently incorporated in the scheduling of irrigation and the low irrigation efficiencies (60%) obtained at the beginning of the irrigated season could be improved by minimising the large post-planting irrigation depths given to corn to promote its emergence. The salinity of the irrigation water was low (EC=0.36 dS m−1), but the drainage waters were saline (EC=7.5 dS m−1) and sodic (SAR=10.3 (meq l−1)0.5) (average values for the 1998 hydrological year) due to the dissolution and transport of the salts present in the lutites. The discharge salt loading was linearly correlated (P<0.001) with the volume of drainage. The slope of the daily mass of salts in the drainage waters versus the daily volume of drainage increased at a rate 25% higher in 1997 (7.6 kg m−3) than in 1998 (6.1 kg m−3) due to the higher precipitation in 1997 and the subsequent rising of the saline watertables in equilibrium with the saline lutites. Drainage volumes depended (P<0.001) on irrigation volumes and were very low (194 mm for the 1998 hydrological year), whereas the salt loading was moderate (13.5 Mg ha−1 for the 1998 hydrological year) taking into account the vast amount of salts stored within the lutites. We concluded that the efficient irrigation and the low salinity of the irrigation water in the study area allowed for a reasonable control of the salt loading conveyed by the irrigation return flows without compromising the salinization of the soil’s root-zone.  相似文献   

8.
A 2-year experiment was carried out to investigate the effects of different drip irrigation regimes on distribution and dynamics of soil water and salt in north Xinjiang, China. Five treatments—F7 (0.24 dS m?1 + Once every 7 days), B7 (4.68 dS m?1 + Once every 7 days), S7 (7.42 dS m?1 + Once every 7 days), F10 (0.24 dS m?1 + Once every 10 days) and F3 (0.24 dS m?1 + Once every 3 days)—were designed. For all treatments, additional 150-mm fresh water was applied on 10th November in 2009 (winter irrigation) to leach the accumulated salt. The results revealed that irrigation frequency and water quality had significant effects on the spatial distribution and change of soil water content, soil salt and the crop water consumption rate, but had a limited impact on the seasonal accumulative water consumption, and the cotton yield decreased with the decrease in irrigation frequency and water quality on the whole. During the cotton growing season, results showed that the salt mainly accumulated in the 0- to 60-cm soil layer, while the soil salt in 60- to 100-cm layer changed slightly, indicating that the drip irrigation could not leach the soil salt out of the root zone under the irrigation regimes. Therefore, salt leaching was necessary to maintain the soil water–salt balance and to prevent excessive salt accumulation in the root zone. After the 150-mm winter irrigation and subsequent thawing, soil salts were leached into the deeper layers (below 60 cm), and the soil salt content (SSC) (EC1:5) in root zone in the next year was about 0.2 dS m?1. Moreover, compared to 2009 season, the SSC within the root zone did not increase even the EC of the irrigation water was up to 7.42 dS m?1. Additionally, it is important to note that the results were concluded based on the data of the 2-year experiment; further studies are need to optimize winter irrigation amount and assess the sustainability of saline water irrigation since long-term utilization of saline water may lead to soil degradation.  相似文献   

9.
In 2006 a comprehensive sampling program was undertaken in two pre-selected peri-urban villages in Faisalabad, Pakistan to evaluate the soil and agronomic impacts of long-term (25–30 years) untreated wastewater re-use on wheat grain and straw yields and attributes of wheat straw fodder quality. Soil SAR, ESP, RSC and ECe were 63%, 37%, 31%, and 50% higher under wastewater (WW) as compared with canal water (CW) irrigated plots. Further, 2.7 and 6.65 fold increases in soil NO 3 ? + NO 2 ? - N and Olsen-P were observed in WW as compared with CW irrigated plots. However, no significant differences in grain yield, wheat straw biomass, or fodder quality attributes were observed between WW and CW irrigated plots. In addition, for both CW and WW irrigated plots wheat straw, Cd and Pb concentrations were orders of magnitude below the EC Maximum permissible levels for Pb and Cd in feed materials and thus pose no threat to the fodder-livestock food chain. Further, elevated soil N associated with WW irrigated plots has a significant (p?<?0.01) positive influence on fodder quality by increasing the N content. Factorial ANOVA with covariance indicates that effective management of the elevated soil ECe in WW irrigated plots would increase grain yield and wheat straw biomass by 853 kg ha?1 (19.5%) and 819 kg ha?1 (18.6%) respectively as compared with CW irrigated plots. In Faisalabad, if managed appropriately to address emerging salinity issues the contribution of wastewater irrigation to the achievement of MDGs 1 and 7 could be significant if adverse impacts remain as marginal as found in this study.  相似文献   

10.
Coal bed natural gas (CBNG) extraction in the Powder River (PR) Basin of Wyoming and Montana produces modestly saline-sodic wastewater, which may have electrical conductivity (EC) and sodium adsorption ratios (SAR) exceeding accepted thresholds for irrigation (EC = 3 dS m−1, SAR = 12 (mmolc l−1)1/2. As an approach to managing large volumes of CBNG-produced water, treatment processes have been developed to adjust produced water salinity and sodicity to published irrigation guidelines and legislated in-stream standards. The objective of this laboratory study was to assess acute and chronic soil solution EC and SAR responses to various wetting regimes simulating repeated flood irrigation with treated CBNG product water, followed by single rainfall events. Fifty-four soil samples from irrigated fields in southeast Montana were subjected to simulated PR water or CBNG water treated to EC and SAR values accepted as thresholds for designation of saline × sodic water, in a single wetting event, five wetting–drying events, or five wetting–drying events, followed by leaching with distilled water. Resultant saturated paste extract EC (ECe) and SAR of soils having <33% clay did not differ from one another, but resulting ECe and SAR were all less than those for soil having >33% clay. Repeated wetting with PR water having EC of 1.56 dS m−1 and SAR of 4.54 led to SAR <12, but brought ECe near 3 dS m−1. Repeated wetting with water having salinity = 3.12 dS m−1 and SAR = 13.09 led to ECe >3 dS m−1 and SAR near 12. Subsequent inundation and drainage with distilled water, simulating rainfall-quality leaching, reduced ECe and SAR more often in coarse-textured, high salt content soils than in finer-textured, lower salt content soils. Decreases in ECe upon leaching with distilled water were of greater magnitude than corresponding decreases in SAR, reinforcing supposition of sodium-induced dispersion of fine-textured soils as a consequence of rainfall following irrigation with water having salinity and sodicity levels equal to previously published thresholds.  相似文献   

11.
A 3-year column lysimeter experiment was conducted with cotton (Gossypium hirsutum L.) to determine the influence of shallow groundwater salinity on groundwater uptake. Nonsaline (0.3 dS m−1) irrigation water was applied at 7-day intervals throughout the growing season, with the cotton allowed to use stored soil water and groundwater as root water uptake permitted. Groundwater salinities ranging from 0.3 dS m−1 electrical conductivity (ECw) to 30.8 dS m−1 were evaluated. Water for leaching was applied following harvest each year in amounts adequate to produce a nonsaline soil profile at the beginning of each year. Equations were developed to describe relationships between day of year, growth stage or growing degree days and shallow groundwater uptake. Groundwater contributed about 30 to 42% of seasonal total evapotranspiration (ET) in treatments with groundwater salinity ≤ 20 dS m−1 but declined to 12 to 19% of total ET at higher salinity levels.  相似文献   

12.
Based on a field study on the semi-arid Loess Plateau of China, the strategies of limited irrigation in farmland in dry-period of normal-precipitation years are studied, and the effects on water use and grain yield of spring wheat of dry-period irrigation and fertilizer application when sowing are examined. The study includes four treatments: (1) with 90 mm dry-period irrigation but without fertilizer application (W); (2) with fertilizer application but without dry-period irrigation (F); (3) with 90 mm dry-period irrigation plus fertilizer application (WF); (4) without dry-period irrigation and fertilizer application (CK). The results indicate that dry-period irrigation resulted in larger and deeper root systems and larger leaf area index (LAI) compared with the non-irrigated treatments. The root/shoot ratio (R/S) in the irrigated treatments was significantly higher than in the non-irrigated treatments. The grain yields in F, W and WF are 1509, 2712 and 3291 kg ha−1, respectively, which are 13.7, 104.3 and 147.9% higher than that (1328 kg ha−1) of CK, and at the same time the grain yields in W and WF are also significantly higher than in F. Water use efficiencies (WUE) in terms of grain yield are 5.70 and 6.91 kg ha−1 mm−1 in W and WF, respectively, being 65.7 and 101.1% higher than that (3.44 kg ha−1 mm−1) of CK. The highest WUE and grain yield consistently occurred in WF, suggesting that the combination of dry-period irrigation and fertilizer application has a beneficial effect on improving WUE and grain yield of spring wheat.  相似文献   

13.
The physiological behavior and yield response of maize under irrigation with saline water was studied in the laboratory and in the field. In the laboratory, the germination rate decreased only when the electrical conductivity (EC) of the substrate solution was above 17 dS/m. The osmotic potential of germinating maize seedlings decreased in proportion to the decrease in osmotic potential of the substrate.In the field, two maize cultivars (a field maize and a sweet maize) were irrigated alternately with saline (11 days from sowing), fresh (21 days from emergence), and saline (from day 33 to harvest) water and compared with maize irrigated with saline water continuously throughout the season. Four levels of irrigation water salinity were used (ECi = 1.2, 4.5, 7.0 and 10.5 dS/m).In the field no osmotic adjustment by the leaf sheaths of plants in response to salinity was observed. The osmotic potential of corn leaf sheaths (π) decreased with ontogeny in all treatments. The midday leaf water potential (ψL) in maize irrigated with 10.5 dS/m water was 0.75 MPa lower than in plants irrigated with 1.2 dS/m water.In the continuous treatment grain yield was reduced significantly with each increase in salt concentration, and the relationship between relative yield (y) and ECi could be expressed as y = 100?8.7 (ECi-0.84). With alternating irrigation and 7.0 dS/m treatment the grain yield was the same as in the low EC treatment (6.98 kg/m2).  相似文献   

14.
Rice (Oryza sativa L.) cultivation under non-flooded (NF) condition is a new alternative to the conventional flooded (CF) rice cultivation system in the regions where rainfall and fresh water resources are limited. Non-flooded rice cultivation may mediate rice growth performance and mulching may be good practice to reduce evapotranspiration and increase water use efficiency (WUE). The research objectives of this study were to investigate the effects of non-flooded cultivation with straw mulching on the rice agronomic traits and water use efficiency of the second rice cropping season (late rice). The treatments were conventional flooded rice cultivation, non-flooded rice cultivations without (NF-ZM) and with rice straw mulching (NF-SM). Irrigation water was 19950 m3 ha−1 in 2003 and 15,850 m3 ha−1 in 2004 in the CF treatments and 7200 m3 ha−1 in 2003 and 5045 m3 ha−1 in 2004 in the non-flooded rice fields (NF-ZM and NF-SM treatments).The field measurements showed that water seepage was 13,442 m3 ha−1 in the CF treatment, 5510 m3 ha−1 in the NF-ZM treatment and 5424 m3 ha−1 in the NF-SM treatment. Rice straw mulching decreased evapotranspiration by 33% and 63% (in 2003), 36.5% and 57.1% (in 2004) to the NF-ZM treatment and CF treatment, respectively. Compared with the NF-ZM treatment, mulch application significantly increased the leaf area per plant, main root length, tap root length and root dry weight per plant of crop. The yield of the NF-SM treatment (2003: 6489 kg/hm2; 2004: 8574.8 kg/hm2) was similar with the value of the CF treatment (2003: 6811.5; 2004: 8630.5 kg/hm2), and much higher than the NF-ZM treatment (2003: 4716; 2004: 6394.8 kg/hm2). The order of irrigation water use efficiency (IWUE) and water use efficiency were as follows: NF-SM > NF-ZM > CF.  相似文献   

15.
A field experiment was conducted for 3 years to evaluate the effect of deficit irrigation under different soil management practices on biomass production, grain yield, yield components and water productivity of spring wheat (Triticum estivum L.). Soil management practices consisted of tillage (conventional and deep tillage) and Farmyard manure (0 and 10 t ha?1 FYM). Line source sprinkler laterals were used to generate one full- (ETm) and four deficit irrigation treatments that were 88, 75, 62 and 46 % of ETm, and designated as ETd1, ETd2, ETd3, and ETd4. Deep tillage significantly enhanced grain yield (14–18 %) and water productivity (1.27–1.34 kg m?3) over conventional tillage. Similarly, application of FYM at 10 t ha?1 significantly improved grain yield (10–13 %) and water productivity (1.25–1.31 kg m?3) in comparison with no FYM. Grain yield response to irrigation varied significantly (5,281–2,704 kg ha?1) due to differences in soil water contents. Water productivity varied from 1.05 to 1.34 kg m?3, among the treatments in 3 years. The interactive effect of irrigation × tillage practices and irrigation × FYM on grain yield was significant. Yield performance proved that deficit irrigation (ETd2) subjected to 75 % soil water deficit had the smallest yield decline with significant water saving would be the most appropriate irrigation level for wheat production in arid regions.  相似文献   

16.
The wheat- (Triticum aestivum L.) and corn- (Zea mays L.) rotation system is important for food security in Northwest China. Grain yield and water-use efficiency [WUE: grain yield/estimated evapotranspiration (ET)] were recorded during a 24-year fertilization trial in Pingliang (Gansu, China). Mean yields of wheat for the 16 years, starting in 1981, ranged from 1.29 Mg ha−1 for unfertilized plots (CK) to 4.71 Mg ha−1 for plots that received manure (M) annually with nitrogen (N) and phosphorus (P) fertilizers (MNP). Corn yields for the 6 years, starting in 1979, averaged 2.29 and 5.61 Mg ha−1 for the same respective treatments. Whether the years were dry, normal or wet, average grain yields and WUEs for both crops were consistently highest in the MNP and lowest in the CK treatment, and were always lower in the N than in the M treatment and in all others treatments that received N along with P fertilizers. More importantly, WUEs for MNP and for straw along with N annually and P every second year (SNP) were always higher than the other fertilized treatments in dry years. Compared to yield data, coefficients of variance (CV) for WUEs were consistently low for all treatments, suggesting that WUEs were relatively stable from year to year. Yields and WUEs declined over time, except in the CK and MNP treatments for wheat. Declined yields of wheat for the N and M treatments were comparable, and the decline for the NP treatment was similar to that for the SNP treatment. Likewise, corn yields and WUEs declined for all treatments. Grain yields were significantly correlated with ET, with slopes ranging from 0.5 to 1.27 kg m−3 for wheat and from 1.15 to 2.03 kg m−3 for corn. Balanced fertilization and long-term addition of organic material to soil should be encouraged in this region to maximize the use of stored soil water, arrest grain yields decline, and ensure sustainable productivity using this intensive cereal cropping system.  相似文献   

17.
A great challenge for the agricultural sector is to produce more food from less water, particularly in arid and semi-arid regions which suffer from water scarcity. A study was conducted to evaluate the effect of three irrigation methods, using effluent versus fresh water, on water savings, yields and irrigation water use efficiency (IWUE). The irrigation scheduling was based on soil moisture and rooting depth monitoring. The experimental design was a split plot with three main treatments, namely subsurface drip (SSD), surface drip (SD) and furrow irrigation (FI) and two sub-treatments effluent and fresh water, which were applied with three replications. The experiment was conducted at the Marvdasht city (Southern Iran) wastewater treatment plant during 2005 and 2006. The experimental results indicated that the average water applied in the irrigation treatments with monitoring was much less than that using the conventional irrigation method (using furrows but based on a constant irrigation interval, without moisture monitoring). The maximum water saving was obtained using SSD with 5907 m3 ha−1 water applied, and the minimum water saving was obtained using FI with 6822 m3 ha−1. The predicted irrigation water requirements using the Penman-Monteith equation (considering 85% irrigation efficiency for the FI method) was 10,743 m3 ha−1. The pressure irrigation systems (SSD and SD) led to a greater yield compared to the surface method (FI). The highest yield (12.11 × 103 kg ha−1) was obtained with SSD and the lowest was obtained with the FI method (9.75 × 103 kg ha−1). The irrigation methods indicated a highly significant difference in irrigation water use efficiency. The maximum IWUE was obtained with the SSD (2.12 kg m−3) and the minimum was obtained with the FI method (1.43 kg m−3). Irrigation with effluent led to a greater IWUE compared to fresh water, but the difference was not statistically significant.  相似文献   

18.
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   

19.
Summary An irrigation experiment with water of different salinities (2.8, 7.6 and 12.7 mol Cl m–3) was carried out from 1982 to 1988 in a mature Shamouti orange grove in the coastal plain of Israel. Seasonal accumulation of salts in the soil solution of the root zone (EC of more than 4.0 dS m–1 at the end of the irrigation season) was almost totally leached during the winter. The average annual rainfall of 550 mm reduced EC values below 1.0 dS m–1. Tree growth, as measured by the increase in cross sectional area of main branches, was retarded by saline irrigation water (123, 107 and 99 cm2 growth per tree during six years for the 2.8, 7.6 and 12.7 mol Cl m–3 treatments, respectively). Potassium fertilization (360 kg K2O ha–1) increased yield at all salinity levels during the last three years of the experiment, mainly by increasing fruit size. Saline irrigation water slightly increased sucrose and C1 concentrations in the fruit juice. Salinity decreased transpiration, increased soil water potential before irrigation and decreased leaf water potential. However, the changes in leaf water potential were small. Leaf Cl and Na concentrations increased gradually during the experimental period, but did not reach toxic levels up to the end of the experiment (4.4 g Cl kg–1 dry matter in the high salt treatment vs. 1.7 in the control). Relatively more leaf shedding occurred in the salinized trees as compared to the control. The sour orange root-stock apparently provided an effective barrier to NaCl uptake; therefore, the main effect of salinity was probably osmotic in nature. No interactions were found between N or K fertilization and salinity. Additional N fertilization (160 kg N ha–1 over and above the 200 kg in the control) did not reduce Cl absorption nor did it affect yield or fruit quality. Additional K had no effect on Na absorption but yield and fruit size were increased at all salinity levels. No significant differences were obtained between partial and complete soil surface wetting (30% and 90% of the total soil area resp.) with the same amounts of irrigation water. The effect of salinity on yield over the six years of the experiment was relatively small and occurred only after some years. But, in the last three years salinity significantly reduced average yields to 74.6, 67.1, and 64.2 Mg ha–1 for the three levels of salinity, respectively.These results suggest that saline waters of up to 13 mol Cl m–3 primarily influence the tree water uptake and growth response of Shamouti orange trees, whereas yield was only slightly reduced during six years.  相似文献   

20.
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   

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