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1.
Changes in the hydrologic balance in many irrigation areas, including those in the Murray Basin, Australia, have resulted in high watertables and salinity problems. However, where suitable aquifers exist, groundwater pumping and subsequent irrigation application after mixing with surface waters (referred to as conjunctive water use) can control salinity and watertable depth and improve productivity of degraded land. In order to assess where conjunctive water use will successfully control salinity, it is necessary to estimate the effects of pumped groundwater salinity on rootzone salinity. A simple steady rate model is derived for this purpose from mass conservation of salt and water. The model enables an estimate to be made of rootzone salinity for any particular salinity level of the groundwater being used in conjunction with surface water; this enables calculation of the required crop salt tolerance to prevent yield reductions. The most important input parameters for the model are groundwater salinity, the annual depth of class A pan evaporation, the annual depth of rainfall, the salinity of irrigation water, and a leaching parameter. For model parameters nominated in this paper, where groundwater salinity reaches 5 dS/m a crop threshold salt tolerance greater than 1.6 dS/m is required to avoid yield reductions. Where groundwater salinity approaches 10 dS/m, a crop threshold tolerance of 3 dS/m is required. Whilst the model derived indicates that rootzone salinity is sensitive to groundwater salinity, rootzone salinity is insensitive to leaching for leaching fractions commonly encountered (0.1 to 0.4). The insensitivity to leaching means that it could be expected that similar yields could be attained on heavy or light textured soils. This insensitivity also implies that there is no yield penalty from increasing the mass of pumped salt by pumping to achieve maximum watertable control in addition to leaching. The model developed is also used to estimate yield reductions expected under conjunctive use, for any particular levels of groundwater salinity and crop salt tolerance.  相似文献   

2.
Summary The salt tolerance of mature Santa Rosa plum trees was assessed on 20-year-old trees grown in the San Joaquin Valley of California. The experimental design consisted of six levels of irrigation water salinity (electrical conductivities of 0.3 to 8 dS/m) replicated five times with each replication consisting of ten trees. Salinity treatments imposed in March 1984 did not influence tree yields harvested in June 1984. In 1985, the second year of treatments, yield from the highest salt treatment (electrical conductivity of irrigation water, EC i , of 8 dS/m) was reduced by half; the number of fruit harvested was reduced 40%, and fruit size was reduced significantly. Foliar damage was so severe by the end of 1985 that nonsaline water was applied to the two highest salt treatments (EC i = 6 and 8 dS/m) in an attempt to restore tree vigor. In 1986 salt effects had become progressively worse on the continuing saline treatments. A linear piece-wise salt tolerance curve is presented for soil salinity values, expressed as the electrical conductivity of saturated extracts (EC e ) integrated to a soil depth of 1.2 m over a 2-year period. The salt tolerance threshold for relative yield (Y r ) based on 3 years of data was 2.6 dS/m and yield reduction at salinity levels beyond the threshold was 31% per dS/m (Y ir=100 – 31 [EC e – 2.6]j). Significant foliar damage occurred when leaf chloride concentrations surpassed 200 mmol/kg of leaf dry weight (0.7%). Sodium concentrations in the leaves remained below 10 mmol/kg (0.02%) until foliar damage became severe. This suggests that chloride was the dominant ion causing foliar damage.  相似文献   

3.
Salt tolerance of mature Williams Bon Cretien pear trees was assessed in a field trial on a duplex, slowly permeable clay loam. The trees were irrigated with a range of salinities; electrical conductivity of irrigation water (ECw) of 0.2 to 1.4 dS/m by flood for seven years or 0.2 to 2.1 dS/m by microjet sprinklers for nine years. Water-table levels were maintained below 3 m by a groundwater pump. Yield and leaf ion content were assessed during the treatment period. Aspects of growth and physiology were monitored in the 0.2 and 2.1 dS/m microjet treatments during the seventh irrigation season.Soil profile salinities varied between 3.0 and 4.3 dS/m for the most saline flood treatment and from 1.5 to 2.6 dS/m for the most saline microjet treatment. Soil sodicity (sodium absorption ratio) increased during the experiment, reaching a maximum of 9 in the most saline treatments. The salinity treatments caused reduced yields after seven years. In the most saline treatment (ECw = 2.1 dS/m, microjet-irrigated), yield decreased to about 60 and 50% of the control in the eighth and ninth years, respectively, and 40% of trees were dead in the ninth year. Leaf ion concentrations (in January) of the most saline treatment were at excess levels (>0.1% Cl and >0.02% Na) from 1982 to 1990. There were significant (P<0.01) negative linear relationships between yield in 1990 and leaf Na and Cl, measured both in 1990 and in 1989. During the seventh season of saline irrigation, lateral shoot growth was reduced, leaves and fruit were smaller and leaf fall was earlier in the 2.1 dS/m treatment compared with the control. Dawn and midday water potential and osmotic potential were not significantly affected by saline irrigation. Midday CO2-assimilation rates (A) and leaf conductance to water vapour diffusion (g) were similar for 2.1 dS/m irrigated and control trees, however there was a trend towards a reduction in A and g of these salt-treated trees late in the irrigation season when leaf Na and Cl had increased to 250 and 240 mM (tissue water basis) respectively.  相似文献   

4.
Summary Experiments were conducted in lysimeters (1985) and field plots (1986) to evaluate changes in soil moisture and salinity status following irrigations with different blends of a saline water, SW (ECiw = 6.4 dS/m) and non-saline water, NSW (0.3 dS/m) and their effects on the growth and yield of Mungbean (Vigna radiata L. Wilczek). Normalised to the yield of the treatment receiving NSW (100%), relative seed yields (RY) declined to 73, 11 and 3%, respectively, for the treatments receiving SWNSW blends of 12 (2.5 dS/m), 21 (4.7 dS/m) and SW as such. RY increased to 64 and 74% when NSW was substituted for presowing irrigation and 21 SWNSW blend and SW, respectively were used for postsowing irrigations. Due to moderating effect of rainfall (9.8 cm) during the growing season of 1986, valus of RY obtained with 12 and 21 SWNSW blends were 81 and 42% and increased to 96 and 82% when these waters were applied after presowing irrigation with NSW. Irrigation at presowing with non-saline water leached the salts of shallow depths leading to better germination and initial growth. In addition, plants were able to extract greater amounts of water even from deeper soil layers. The RY of Mungbean was related to the weighted time averaged salinity of the 0–120 cm soil depth (ECe) by RY = 100-20.7 (ECe-1.8). The study indicated that applying NSW for presowing irrigation to Mungbean is more beneficial than using it after blending with saline water.  相似文献   

5.
In order to study the effects of drip irrigation with saline water on waxy maize, three years of field experiments were carried out in 2007-2009 in North China Plain. Five treatments with average salinity of irrigation water, 1.7, 4.0, 6.3, 8.6, and 10.9 dS/m were designed. Results indicated that the irrigation water with salinity <10.9 dS/m did not affect the emergence of waxy maize. As salinity of irrigation water increased, seedling biomass decreased, and the plant height, fresh and dry weight of waxy maize in the thinning time decreased by 2% for every 1 dS/m increase in salinity of irrigated water. The decreasing rate of the fresh ear yield for every 1 dS/m increase in salinity of irrigation water was about 0.4-3.3%. Irrigation water use efficiency (IWUE) increased with the increase in salinity of irrigation water when salinity was <10.9 dS/m. Precipitation during the growing period significantly lightened the negative impacts of irrigation-water salinity on the growth and yield. Soil salinity in depth of 0-120 cm increased in the beginning of irrigation with saline water, while it was relatively stable in the subsequent year when salinity of irrigation water was not higher than 4.0 dS/m and the soil matric potential (SMP) at 0.2 m directly underneath the drip emitter was controlled above −20 kPa.  相似文献   

6.
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   

7.
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   

8.
Summary Lucerne was irrigated for three years on a slowly permeable, duplex soil, with saline water up to 2.4 dS m–1 without significant yield decline. Irrigation water of 4.5 dS m–1 significantly reduced yield. Lucerne yield was most closely related to the soil ECe of the 0–15 cm depth, rather than the total rootzone, and was described by; Relative yield=100–6.5 (ECe-2.1). While lucerne roots reached depths of at least 150 cm, approximately 80% of total root length was located in the 0–60 cm depth.Increasing salinity increased the plant concentrations of sodium and chloride, however, these changes were not closely related to changes in yield.Soil salinity increased with increasing salinity of the applied water. However, during the irrigation season water penetration and the accumulation of salt within the profile was predominantly restricted to the 0–60 cm depth. No portion of the applied irrigation water was available as a leaching fraction. Any leaching of salts to the watertable, particularly below 120 cm, was due to winter rainfall rather than the application of summer irrigation water.Ripping the soil to a depth of 75 cm increased water infiltration and resulted in increased crop yields, but did not significantly affect the crop relative yield-soil ECe relationship.From the results it is proposed that on the slowly permeable duplex soils, when watertable depth is controlled, management strategies for lucerne irrigated with saline water should be based on controlling the salinity of the shallow soil depths, to 60 cm.  相似文献   

9.
Summary The salt tolerance of guayule (Parthenium argentatum Gray cv. N565-II) was tested in small held plots (silty clay soil) in the Imperial Valley of California. Seedlings were transplanted in October 1981. Differential salination was begun in March 1982 and continued for 4 years by irrigating with waters salinized with NaCl and CaCl2 (1:1 by wt.) to obtain electrical conductivities of 0.8, 1.4, 3, 6, 9, and 12 dS/m. Dry matter, rubber, and resin yields were determined from pollarded plants in February 1984 and uprooted plants in February 1985 and 1986. Rubber concentrations in the woody branches in 1984 and 1985 averaged 6.1 and 7.3%, respectively on a dry weight basis and were not significantly affected by soil salinity. Resin concentrations averaged 8.6% and 7.3% for the two years. In 1986, both rubber and resin concentrations decreased with increased salinity. Rubber and resin concentrations in the root crowns were approximately one percentage point less than those of the shoot. Dry matter and resin yields were not affected by salinity until the time- and depth-averaged electrical conductivity of the saturated-soil extracts ( ) taken from the rootzone (0–90 cm) exceeded 8.7 dS/m. Above 8.7 dS/m, both yields decreased 11.6% per dS/m increase in . Rubber yields decreased 10.8% per dS/m above a threshold of 7.8 dS/m. Plant mortality rather than growth reduction at high levels of salinity appears to be the limiting factor for rubber production from irrigated guayule.  相似文献   

10.
Summary Corn production on the organic soils of the Sacramento-San Joaquin Delta of California was affected by the salinity of the irrigation water and the adequacy of salt leaching. Full production was achieved on soils that were saline the previous year, provided the electrical conductivity of the irrigation water (ECi) applied by sprinkling was less than about 2 dS/m and leaching was adequate from either winter rainfall or irrigation to reduce soil salinity (ECMSW) below the salt tolerance threshold for corn (3.7 dS/m). For subirrigation, an ECi up to 1.5 dS/m did not decrease yield if leaching had reduced ECMSW below the threshold. If leaching was not adequate, even nonsaline water did not permit full production. In agreement with previous results obtained in a greenhouse, surface irrigation with water of an electrical conductivity of up to 6 dS/m after mid-season (end of July) did not reduce yield below that of treatments where the salinity of the irrigation water was not increased at mid-season. Results also reconfirm the salt tolerance relationship established in the previous three years of the field trial. The earlier conclusion that the irrigation method (sprinkler or subirrigation) does not influence the salt tolerance relationship was also confirmed.This project was sponsored jointly by the California State Water Resource Control Board, the California Department of Water Resources, the University of California, and the Salinity Laboratory of the US Department of Agriculture  相似文献   

11.
In irrigated agriculture, the production of biomass and marketable yield depend largely on the quantity and salinity of the irrigation water. The sensitivity of field-grown muskmelon (Cucumis melo L. cv. Galia) to water deficit was compared, using non-saline (ECi= 1.2 dS m–1) and saline (ECi=6.3 dS m–1) water. Drip irrigation was applied at 2-day intervals at seven different water application rates for each water quality, including a late water-stress treatment. Neutron scattering measurements showed that the soil layers below the root zone remained dry throughout the experiment, indicating negligible deep percolation. Thus, the sum of the seasonal amount of applied water and the change in soil moisture approximated the cumulative evapotranspiration (ET). Gradual buildup of water and salt stresses resulted in small treatment effects on the size of the vegetative cover and large effects on leaf deterioration and fruit production. Crop responses to salinity may result from an osmotic component of the soil water potential or from other salt effects on the crop physiology. Relating plant data to cumulative ET allowed a distinction to be made between the effect on water availability and specific salinity effects. The relation between fruit fresh weight and ET was not sensitive to ECi. The slopes for fruit dry weights were also insensitive to ECi but the intercept was larger for saline treatments. At any given ET saline water increased fruit number, increased fruit dry matter content and decreased fruit netting, in comparison with non-saline water. The combination of salinity and soil-water deficit was detrimental to fruit quality. Saline soil-water deficit decreased the percentage of marketable (netted) fruit and caused an early end to the period of marketable fruit production. Non-saline soil-water deficit increased the percentage of marketable fruit and had no effect on the duration of the production period. Late non-saline water stress caused a pronounced increase in the percentage of marketable fruit.  相似文献   

12.
A model was developed to predict rootzone salinity under different irrigation practices on different soil types, with similar rainfall but different monthly distributions. A rootzone daily water and salt balance was performed using eight scenarios: two soil types (coarse textured vs. fine textured), two multi-year series of actual rainfall data and two irrigation practices (surface with fixed number of irrigations and ET-based sprinkler irrigation). All factors influenced the mean electrical conductivity (EC) of the rootzone in the growing season (ECeS): (i) Surface irrigation led to lower ECeS than sprinkler irrigation; (ii) Winter-concentrated rainfall caused lower ECeS than rainfall distributed uniformly throughout the year; and (iii) Coarser-textured soil usually resulted in lower ECeS than the finer textured. The ECeS was related to the total precipitation of the hydrologic year and to the annual leaching fraction (LF) but surprisingly not to the seasonal LF. In most cases, the model predicted lower ECeS than the FAO steady-state approach. Therefore, considering these site-specific features could lead to lower leaching requirements and the safe use of higher salinity water.  相似文献   

13.
The field experiments were carried out in 2007 and 2008 to study the effects and strategies of drip irrigation with saline water for oleic sunflower. Five treatments of irrigation water with average salinity levels of 1.6, 3.9, 6.3, 8.6, and 10.9 dS/m were designed. For each treatment, 7 mm water was applied when the soil matric potential (SMP) 0.2 m directly underneath the drip emitters was below −20 kPa, except during the seedling stage. To ensure the seedling survival, 28 mm water was applied after sowing during the seedling stage. Results indicate that amount of applied water decreases as salinity level of irrigation water increases. The emergence will be delayed when the salinity level of irrigation water is higher than 6.3 dS/m, but these differences will be alleviated if there is rainfall during emergence period. The final emergence percentage is not changed when salinity level of irrigation is less than 6.3 dS/m, and the percentage decreases by 2.0% for every 1 dS/m increase when the salinity level of irrigation water is above 6.3 dS/m, but the decreasing rate will be reduced if there is rainfall. The plant height and yield decrease with the increase of salinity of irrigation water. The height of plants decreases by 0.6-1.0% for every 1 dS/m increase in salinity level of irrigation water. The yield decreases by 1.8% for every 1 dS/m increase in salinity level of irrigation water, and irrigation water use efficiency (IWUE) increases with increase in salinity of irrigation water. The soil salinity increases as the salinity of irrigation water increasing after drip irrigation with saline water in the beginning, but the soil salinity in soil profile from 0 to 120 cm depths can be maintained in a stable level in subsequent year irrigation with saline water. From the view points of yield and soil salt balance, it can be recognized even as the salinity level of irrigation water is as high as 10.9 dS/m, saline water can be applied to irrigate oleic sunflower using drip irrigation when the soil matric potential 0.2 m directly under drip emitter is kept above −20 kPa and the beds are mulched in semi-humid area.  相似文献   

14.
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   

15.
Supplemental irrigation of wheat with saline water   总被引：3，自引：0，他引：3  
In arid and semi-arid regions, both rainfall and surface irrigation water supplies are unreliable and inadequate to meet crop water requirement. Groundwater in these regions is mainly marginally saline (2-6 dS/m) to saline (>6 dS/m) and could be exploited to meet crop water requirement if no adverse effects on crops and land resource occur. The fear of adverse effects has often restricted the exploitation of naturally occurring saline water. The results reveal that substituting a part or all except pre-sowing irrigation with saline water having an electrical conductivity (ECiw) of 8 dS/m is possible for cultivation of wheat. Similarly, saline water with ECiw ranging between 8 and 12 dS/m could be used to supplement at least two irrigations to obtain 90% or more of the optimum yield. In low rainfall years, the use of such waters for all irrigations, except pre-sowing, produced more yield than skipping irrigations. Apparently, even at this level of osmotic salt stress, matric stress is more harmful. Thus, it would be interesting to use such waters for wheat production in monsoon climatic regions.  相似文献   

16.
Saline groundwater is often found at shallow depth in irrigated areas of arid and semi-arid regions and is associated with problems of soil salinisation and land degradation. The conventional solution is to maintain a deeper water-table through provision of engineered drainage disposal systems, but the sustainability of such systems is disputed. This shallow groundwater should, however, be seen as a valuable resource, which can be utilised via capillary rise (i.e. sub-irrigation). In this way, it is possible to meet part of the crop water requirement, even where the groundwater is saline, thus decreasing the need for irrigation water and simultaneously alleviating the problem of disposing of saline drainage effluent. Management of conditions within the root zone can be achieved by means of a controlled drainage system.A series of lysimeter experiments have permitted a detailed investigation of capillary upward flow from a water-table controlled at shallow depth (1.0 m) under conditions of moderately high (5 mm/day) evaporative demand and with different levels of salinity. Experiments were conducted on a wheat crop grown in a sandy loam soil. Groundwater salinity was held at values from 2 to 8 dS/m while supplementary (deficit) irrigation was applied at the surface with salinity in the range 1-4 dS/m.Our experiments show that increased salinity decreased total water uptake by the crop, but in most treatments wheat still extracted 40% of its requirement from the groundwater, similar to the proportion reported for non-saline conditions. Yield depression was limited to 30% of maximum when the irrigation water was of relatively good quality (1 and 2 dS/m) even with saline groundwater (up to 6 dS/m). Crop water productivity (grain yield basis) was around 0.35 kg/m3 over a wide range of salinity conditions when calculated conventionally on the basis of total water use, but was generally above 1.0 kg/m3 if calculated on the basis of irrigation input only.  相似文献   

17.
The effects of multiple irrigation regimes on the relationships among tree water status, vegetative growth and productivity within a super-high-density (SHD) “Arbequina” olive grove (1950 tree/ha) were studied for three seasons (2008–2010). Five different irrigation levels calculated as percentage of crop irrigation requirement using FAO procedures (Allen et al. in Crop evapotranspiration. Guidelines for computing crop water requirements. Irrigation and drainage paper 56. FAO, Rome, 1998) were imposed during the growing season. Periodically during the growing season, daytime stem water potential (Ψ STEM), inflorescences per branch, fruits per inflorescence and shoot absolute growth rate were measured. Crop yield, fruit average fresh weight and oil polyphenol content were measured after harvest. The midday Ψ STEM ranged from ?7 to ?1.5 MPa and correlated well enough with yield efficiency, crop density and fruit fresh weight to demonstrate its utility as a precise method for determining water status in SHD olive orchards. The relationships between midday Ψ STEM and the horticultural parameters suggest maintaining Ψ STEM values between ?3.5 and ?2.5 MPa is optimal for moderate annual yields of good quality oil. Values below ?3.5 MPa reduced current season productivity, while values over ?2.5 MPa were less effective in increasing productivity, reduced oil quality and produced excessive crop set that strongly affected vegetative growth and fruit production the following season. On the basis of the result given here, irrigation scheduling in the new SHD orchards should be planned on a 2-year basis and corrected annually based on crop load. Collectively, these results suggest that deficit irrigation management is a viable strategy for SHD olive orchards.  相似文献   

18.
Drip irrigation of cotton with saline-sodic water   总被引：3，自引：0，他引：3  
Summary A two-year study was conducted in the Negev region of Israel, using the drip method, to determine the effect of four levels of water quality (EC =1.0, 3.2, 5.4 and 7.3 dS/m) in combination with three soil amendment treatments (gypsum spread on the soil surface along the drip laterals after planting, injection of H2SO4 into the water during each irrigation, and a control) on plant response, salt distribution in the soil profile, and soil sodification processes. Salinity did not reduce yields even at the highest level, in spite of sodium and chloride accumulation. The highest seed cotton yield (6.4 t/ha) was obtained with the local well water (EC =3.2 dS/m), indicating an optimal response to salinity. The addition of soil amendments during the irrigation season, although reducing exchangeable sodium accumulation near the emitter, endangers the next crop by increasing sodium accumulation under the plant row. It is therefore, recommended that the amendment be applied only before the winter.Contribution from the Agricultural Research Organization, Israel. No. 1131-E, 1984 series  相似文献   

19.
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   

20.
Salinity sensitivity of sorghum at three growth stages   总被引：1，自引：0，他引：1  
Summary The relative salt tolerance of two sorghum cultivars [Sorghum bicolor (L.) Moench., cvs. Northrup King 265 and Asgrow Double TX] at three different stages of growth was determined in a greenhouse experiment. Plants were grown in sand cultures irrigated four times daily with modified Hoagland's solution. A nonsaline solution and six solutions salinized with NaCl and CaCl2 (2: 1 molar ratio) provided treatments with osmotic potentials (s) ranging from –0.05 to –1.05 MPa. The saline treatments were imposed for 30 days beginning at either Stage 1, 4, or 7 as defined by Vanderlip and Reeves (Agron J. 64:13, 1972). The 30-day stages are referred to here as the vegetative, reproductive and maturation stages although the first stage may have included initial panicle differentiation. Both cultivars were most sensitive to salinity during the vegetative stage and least sensitive during maturation. Based on a nonlinear least-squares analysis, grain yield reductions of 50% were predicted at s=–0.68, –1.02, and –1.14 MPa for NK265 and at –0.62, –1.00, and –1.10 MPa for Double TX when salinized during the vegetative, reproductive, and maturation stages, respectively. Although salinity had no significant effect on mean kernel weights, significant growth stage effects and interaction indicated that kernels were heaviest for plants salinized during the vegetative stage. Stover yields were significantly reduced by salination during the vegetative stage but were unaffected when plants were salinized during the maturation stage. Salination during the reproductive stage also decreased stover yield of Double TX but the effect was smaller than that during the first stage. Stover yield of NK265 was unaffected by salinity at this stage.Mineral analysis of the first leaf below the flag leaf at harvest indicated that both cultivars tended to exclude Na from the upper leaves. Ca and Cl concentrations increased with increased salinity in plants salinized during the maturation stage but salination in earlier stages decreased Ca concentration of this upper leaf at harvest and had no effect on the final Cl concentration. Phosphate and K concentrations decreased when plants were salinized during the third stage but increased when plants were salinized during the vegetative and reproductive stages. Mg was unaffected by salinization during the first and last stage but decreased when plants were salinized,during the reproductive stage. An extensive data base now exists which describes the salt tolerances of many different crops (Maas and Hoffman 1977; Maas 1986). These data express yield responses as a function of the average salt concentration in the rootzone. Generally, these data apply only if salinity is fairly uniform from the seedling stage to maturity. Except for germination, little information exists on the tolerances of crops at different stages of growth. Such information could be invaluable to optimize the use of limited water resources. Knowledge that crops are more tolerant during some stages of growth will improve new strategies for utilizing saline drainage waters (Rhoades 1984).Several studies indicate that tolerances do change as the crop develops and matures, but none of these studies completely separated the effects of duration of treatment from the stage of growth that the crop was treated (Ayers et al. 1952; Kaddah and Ghowail 1964; Kovalskaia 1958; Lunin et al. 1961 a, 1961 b; Maas et al. 1983; Ogo and Sasai 1955; Piruzyan 1959; Verma and Bains 1974). Comparisons of sensitivity during specific phenological stages are confounded when treatment periods are of unequal duration.This study was initiated to determine the sensitivity of grain sorghum [Sorghum bicolor (L.) Moench] to salinity during three 30-day periods of growth. Francois et al. (1984) recently reported that sorghum is a moderately salt-tolerant crop. In field plot tests, grain yields of two cultivars decreased 16% per unit increase in salinity (electrical conductivity of saturated soil extracts from the rootzone) above 6.8 dS/m. They further reported that both cultivars were significantly more tolerant at germination than at later stages of growth. Soil water salinities above 8.2 dS/m delayed germination but full germination occurred within 10 days at salinities up to 22 dS/m. Treatments in the present study were designed to assess plant growth and yield responses to 30-day exposures to salinity beginning at either the 2-leaf stage, at the beginning of rapid culm elongation, or after anthesis.  相似文献   

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