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1.
Field experiments were conducted for 2 years to investigate the effects of various levels of nitrogen (N) and methods of cotton planting on yield, agronomic efficiency of N (AEN) and water use efficiency (WUE) in cotton irrigated through surface drip irrigation at Bathinda situated in semi-arid region of northwest India. Three levels of N (100, 75 and 50% of recommended N, 75 kg ha−1) were tested under drip irrigation in comparison to 75 kg of N ha−1 in check-basin. The three methods of planting tried were; normal sowing of cotton with row to row spacing of 67.5 cm (NS), normal paired row sowing with row to row spacing of 35 and 100 cm alternately (NP) and dense paired row sowing with row to row spacing of 35 and 55 cm alternately resulting in total number rows and plants to be 1.5 times (DP) than NS and NP. In NS there was one lateral along each row, but in paired sowings there was one lateral between each pair of rows. Consequently the number of laterals and quantity of water applied was 50 and 75% in NP and DP, respectively, as compared with NS in which irrigation water applied was equivalent to check-basin.Drip irrigation under NS resulted in an increase of 258 and 453 kg ha−1 seed cotton yield than check-basin during first and second year, respectively, when same quantity of water and N was applied. Drip irrigation under dense paired sowing (DP) in which the quantity of irrigation water applied was 75% as compared with NS, further increased the yield by 84 and 101 kg ha−1 than NS during first and second year, respectively. Drip irrigation under NP, in which the quantity of water applied and number of laterals used were 50% as compared with drip under NS, resulted in a reduction in seed cotton yield of 257 and 112 kg ha−1 than NS during first and second year, respectively. However, the yield obtained in NP under drip irrigation was equivalent to yield obtained in NS under check-basin during first year but 341 kg ha−1 higher yield was obtained during second year. The decrease in N applied, irrespective of methods of planting, caused a significant decline in seed cotton yield during both the years. Water use efficiency (WUE) under drip irrigation increased from 1.648 to 1.847 and from 0.983 to 1.615 kg ha−1 mm−1 during first and second year, respectively, when the same quantity of N and water was applied. The WUE further increased to 2.125 and 1.788 kg ha−1 mm−1 under DP during first and second year, respectively. The agronomic efficiency of nitrogen was higher in drip than check-basin during both the years when equal N was applied. The WUE decreased with decrease in the rate of N applied under fertigation but reverse was true for AEN. It is evident that DP under drip irrigation resulted in higher seed cotton yield, WUE and AEN than NS and also saved 25% irrigation water as well as cost of laterals.  相似文献   

2.
The experiment aimed at evaluating the yield and quality response of broccoli (Brassica oleracea L. var. italica) to applied irrigation water and nitrogen by drip irrigation method during the spring and autumn cultivation periods of 2007. Irrigation water was applied based on a ratio of Class A pan evaporation (kcp = 0.50, 0.75, 1.00 and 1.25) with 7 days interval. Also, the effect of four nitrogen levels (0 kg ha−1, 150 kg ha−1, 200 kg ha−1 and 250 kg ha−1) was compared with each treatment. The seasonal evapotranspiration in the treatments varied from 233 mm to 328 mm during the spring period and from 276 mm to 344 mm during the autumn period. The highest broccoli yield was obtained in the spring period as 11.02 t ha−1 and in the autumn period as 4.55 t ha−1. In general, there were statistical differences along nitrogen does with respect to yield and yield components while there were no statistically significant differences in the yield and yield components among irrigation regimes. Both yield and yield parameters in the spring period were found to be higher than that of the autumn period due to the low temperature and high rainy days in autumn. Irrigation water use efficiency (IWUE) ranged from 3.78 kg m−3 to 14.61 kg m−3 during the spring period and from 1.89 kg m−3 to 5.93 kg m−3 during the autumn period. On the other hand, nitrogen use efficiency (NUE) changed as 37.32-73.13% and 13.08-22.46% for spring and autumn season, respectively.  相似文献   

3.
This paper reports the effects of irrigation amount and partial rootzone drying (PRD) on water relations, growth, yield and wine quality of Vitis vinifera cv. ‘Tempranillo’ during two consecutive years in a commercial vineyard with a deep, light-clay soil located in Requena, Valencia, Spain. Partial rootzone drying applied at two amounts (100% and 50% of the estimated crop evapotranspiration), was compared to conventional drip irrigation, and also to rainfed vines. Results showed that the effects of irrigation amount on yield and wine quality were different between years. In 2003 with low yield values (around 6.3 t ha−1) irrigation did neither affect grape production nor wine quality. However, in the following year, with much higher general yield (17 t ha−1), the high irrigation dose increased yield by 30% compared to rainfed vines and it also increased must total soluble solids and wine alcohol content. In both seasons, PRD did not significantly affect physiological parameters, nor growth, yield or fruit and wine quality, when compared to the same amount of water applied by conventional drip irrigation. Overall these results suggest that, under our experimental conditions, it was the irrigation amount rather than the system of application what affected vine performance, indicating the difficulties of successfully employing the PRD type of irrigation with a drip system in heavy and deep soils.  相似文献   

4.
Rapid urbanization and industrialization have increased the pressure on limited existing fresh water to meet the growing needs for food production. Two immediate responses to this challenge are the efficient use of irrigation technology and the use of alternative sources of water. Drip irrigation methods may play an important role in efficient use of water but there is still limited information on their use on sugar beet crops in arid countries such as Iran. An experiment was conducted to evaluate the effects of irrigation method and water quality on sugar beet yield, percentage of sugar content and irrigation water use efficiency (IWUE). The irrigation methods investigated were subsurface drip, surface drip and furrow irrigation. The two waters used were treated municipal effluent (EC = 1.52 dS m−1) and fresh water (EC = 0.509 dS m−1). The experiments used a split plot design and were undertaken over two consecutive growing seasons in Southern Iran. Statistical testing indicated that the irrigation method and water quality had a significant effect (at the 1% level) on sugar beet root yield, sugar yield, and IWUE. The highest root yield (79.7 Mg ha−1) was obtained using surface drip irrigation and effluent and the lowest root yield (41.4 Mg ha−1) was obtained using furrow irrigation and fresh water. The highest IWUE in root yield production (9 kg m−3) was obtained using surface drip irrigation with effluent and the lowest value (3.8 kg m−3) was obtained using furrow irrigation with fresh water. The highest IWUE of 1.26 kg m−3 for sugar was obtained using surface drip irrigation. The corresponding efficiency using effluent was 1.14 kg m−3. Irrigation with effluent led to an increase in the net sugar yield due to an increase in the sugar beet root yield. However, there was a slight reduction in the percentage sugar content in the plants. This study also showed that soil water and root depth monitoring can be used in irrigation scheduling to avoid water stress. Such monitoring techniques can also save considerable volumes of irrigation water and can increase yield.  相似文献   

5.
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   

6.
Cotton (Gossypium hirsutum L.) is the most important industrial and summer cash crop in Syria and many other countries in the arid areas but there are concerns about future production levels, given the high water requirements and the decline in water availability. Most farmers in Syria aim to maximize yield per unit of land regardless of the quantity of water applied. Water losses can be reduced and water productivity (yield per unit of water consumed) improved by applying deficit irrigation, but this requires a better understanding of crop response to various levels of water stress. This paper presents results from a 3-year study (2004-2006) conducted in northern Syria to quantify cotton yield response to different levels of water and fertilizer. The experiment included four irrigation levels and three levels of nitrogen (N) fertilizer under drip irrigation. The overall mean cotton (lint plus seed, or lintseed) yield was 2502 kg ha−1, ranging from 1520 kg ha−1 under 40% irrigation to 3460 kg ha−1 under 100% irrigation. Mean water productivity (WPET) was 0.36 kg lintseed per m3 of crop actual evapotranspiration (ETc), ranging from 0.32 kg m−3 under 40% irrigation to 0.39 kg m−3 under the 100% treatment. Results suggest that deficit irrigation does not improve biological water productivity of drip-irrigated cotton. Water and fertilizer levels (especially the former) have significant effects on yield, crop growth and WPET. Water, but not N level, has a highly significant effect on crop ETc. The study provides production functions relating cotton yield to ETc as well as soil water content at planting. These functions are useful for irrigation optimization and for forecasting the impact of water rationing and drought on regional water budgets and agricultural economies. The WPET values obtained in this study compare well with those reported from the southwestern USA, Argentina and other developed cotton producing regions. Most importantly, these WPET values are double the current values in Syria, suggesting that improved irrigation water and system management can improve WPET, and thus enhance conservation and sustainability in this water-scarce region.  相似文献   

7.
Field experiment was carried out to investigate the effect of soil matric potential (SMP) on tomato yield, evapotranspiration (ET), water use efficiency (WUE) and irrigation water use efficiency (IWUE) under drip irrigation condition in North China Plain. The experiment included five treatments, which controlled SMP at 0.2 m depth immediately under drip emitter higher than −10 (S1), −20 (S2), −30 (S3), −40 (S4) and −50 kPa (S5), respectively, after tomato plant establishment. The results showed that different SMP affected irrigation amount and tomato ET. Irrigation amount decreased from 185 mm (S1) to 83.6 mm (S5) in 2004, and from 165 mm (S1) to 109 mm (S5) in 2005, respectively. The ET decreased from 270 mm (S1) to 202 mm (S5) in both years. However, it was found that SMP did not affect the tomato yield significantly, for the range of SMP investigated. Both WUE and IWUE increased as SMP decreased. The maximum WUE (253 and 217 kg/ha mm) and IWUE (620 and 406 kg/ha mm) were for S5 in 2 years, whereas the minimum WUE (178 and 155 kg/ha mm) and IWUE 261 and 259 kg/ha mm) were for S1 in 2004 and 2005. Based on the above results, therefore, it is recommended that if the tomatoes are well irrigated (SMP is higher than −20 kPa) during establishment, controlling SMP higher than −50 kPa at 0.2 m depth immediately under drip emitter can be used as an indicator for drip irrigation scheduling during following period of tomato growth in North China Plain.  相似文献   

8.
Tomato production systems in Florida are typically intensively managed with high inputs of fertilizer and irrigation and on sandy soils with low inherent water and nutrient retention capacities; potential nutrient leaching losses undermine the sustainability of such systems. The objectives of this 3-year field study were to evaluate the interaction between N-fertilizer rates and irrigation scheduling on crop N and P accumulation, N-fertilizer use efficiency (NUE) and NO3-N leaching of tomato cultivated in a plastic mulched/drip irrigated production system in sandy soils. Experimental treatments were a factorial combination of three irrigation scheduling regimes and three N-rates (176, 220, and 330 kg ha−1). Irrigation treatments included were: (1) surface drip irrigation (SUR) both the irrigation and fertigation line placed underneath the plastic mulch; (2) subsurface drip irrigation (SDI) where the irrigation drip was placed 0.15 m below the fertigation line which was located on top of the bed; and (3) TIME (conventional control) with the irrigation and fertigation lines placed as in SUR and irrigation applied once a day. Except for the TIME treatment all irrigation treatments were soil moisture sensor (SMS)-based with irrigation occurring at 10% volumetric water content. Five irrigation windows were scheduled daily and events were bypassed if the soil water content exceeded the established threshold. The use of SMS-based irrigation systems significantly reduced irrigation water use, volume percolated, and nitrate leaching. Based on soil electrical conductivity (EC) readings, there was no interaction between irrigation and N-rate treatments on the movement of fertilizer solutes. Total plant N accumulation for SUR and SDI was 12-37% higher than TIME. Plant P accumulation was not affected by either irrigation or N-rate treatments. The nitrogen use efficiency for SUR and SDI was on the order of 37-45%, 56-61%, and 61-68% for 2005, 2006 and 2007, respectively and significantly higher than for the conventional control system (TIME). Moreover, at the intermediate N-rate SUR and SDI systems reduced NO3-N leaching to 5 and 35 kg ha−1, while at the highest N-rate corresponding values were 7 and 56 kg N ha−1. Use of N application rates above 220 kg ha−1 did not result in fruit and/or shoot biomass nor N accumulation benefits, but substantially increased NO3-N leaching for the control treatment, as detected by EC monitoring and by the lysimeters. It is concluded that appropriate use of SDI and/or sensor-based irrigation systems can sustain high yields while reducing irrigation application as well as reducing NO3-N leaching in low water holding capacity soils.  相似文献   

9.
A field experiment was conducted for 2 years to investigate the effects of deficit irrigation, nitrogen and plant growth minerals on seed cotton yield, water productivity and yield response factor. The treatment comprises six levels of deficit irrigation (Etc 1.0, 0.9, 0.8, 0.7, 0.6 and 0.5) and four levels of nitrogen (80, 120, 160 and 200 kg N ha−1). These were treatments superimposed with and without plant growth mineral spray. Furrow irrigation treatments were also kept. Cotton variety Ankur-651 Bt was grown during 2006 and 2007 cotton season. Drip irrigation at 1.0 Etc saved 26.9% water and produced 43.1% higher seed cotton yield over conventional furrow irrigation (1.0 Etc). Imposing irrigation deficit of 0.8 Etc caused significant reduction in seed cotton yield to the tune of 9.3% of the maximum yield. Further increase in deficit irrigation from 0.7 Etc to 0.5 Etc significantly decreased seed cotton yield over its subsequent higher irrigation level. Decline in the yield under deficit irrigation was associated with reduction in number of bolls plant−1 and boll weight. Nitrogen at 200 kg ha−1 significantly increased mean seed cotton yield by 36.3% over 80 kg N ha−1. Seed cotton yield tended to increase linearly up to 200 kg N ha−1 with drip Etc 0.8 to drip Etc 1.0. With drip Etc 0.6-0.5, N up to 160 kg ha−1 provided the highest yield, thereafter it had declined. Foliar spray of plant growth mineral (PGM) brought about significant improvement in seed cotton yield by 14.1% over control. The water productivity ranged from 0.331 to 0.491 kg m−3 at different irrigation and N levels. On pooled basis, crop yield response factor of 0.87 was calculated at 20% irrigation deficit.  相似文献   

10.
Expected yield losses as a function of quality and quantity of water applied for irrigation are required to formulate guidelines for the effective utilisation of marginal quality waters. In an experiment conducted during 2004-2006, double-line source sprinklers were used to determine the separate and interactive effects of saline and alkali irrigation waters on wheat (Triticum aestivum L.). The study included three water qualities: groundwater (GW; electrical conductivity of water, ECw 3.5 dS m−1; sodium adsorption ratio, SAR 9.8 mmol L−1; residual sodium carbonate, RSC, nil) available at the site, and two synthesized waters, saline (SW; ECw 9.4 dS m−1, SAR 10.3 mmol L−1; RSC nil) and alkali (AW; ECw 3.7 dS m−1, SAR 15.1 mmol L−1; RSC 9.6 meq. L−1). The depths of applied SW, AW, and GW per irrigation ranged from 0.7 to 3.5 cm; the depths of applied mixtures of GW with either SW (MSW) or AW (MAW) ranged from 3.2 to 5 cm. Thereby, the water applied for post-plant irrigations using either of GW, SW or AW ranged between 15.2 and 34.6 cm and 17.1 and 48.1 cm during 2004-2005 and 2005-2006, respectively and the range was 32.1-37.0 and 53.1-60.0 cm for MSW or MAW. Grain yields, when averaged for two years, ranged between 3.08 and 4.36 Mg ha−1, 2.57 and 3.70 Mg ha−1 and 2.73 and 3.74 Mg ha−1 with various quantities of water applied using GW, SW and AW, respectively, and between 3.47 and 3.75 Mg ha−1 and 3.63 and 3.77 Mg ha−1 for MSW and MAW, respectively. The water production functions developed for the two sets of water quality treatments could be represented as: RY = 0.528 + 0.843(WA/OPE) − 0.359(WA/OPE)2 − 0.027ECw + 0.44 × 10−2(WA/OPE) × ECw for SW (R2 = 0.63); RY = 0.446 + 0.816(OPE/WA) − 0.326(WA/OPE)2 − 0.0124RSC − 0.55 × 10−4(WA/OPE) × RSC for AW (R2 = 0.56). Here, RY, WA and OPE are the relative yields in reference to the maximum yield obtained with GW, water applied for pre- and post-plant irrigations (cm), and open pan evaporation, respectively. Crop yield increased with increasing amount of applied water for all of the irrigation waters but the maximum yields as obtained with GW, could not be attained even with increased quantities of SW and AW. Increased frequency of irrigation with sprinklers reduced the rate of yield decline with increasing salinity in irrigation water. The sodium contents of plants increased with salinity/alkalinity of sprinkled waters as also with their quantities. Simultaneous decrease in potassium contents resulted in remarkable increase in Na:K ratio.  相似文献   

11.
Tieguanyin Oolong tea (Camellia sinensis (L.) O. Kuntze) is a name brand important commodity for Anxi county, Fujian province in China. Four-year-old tea plants at a tea plantation in Anxi were subjected to six different irrigation treatments (i.e. 5, 10, 15, 20, and 25 d irrigation intervals for T1 to T5 with a rate of 3.5 kg water per plant, plus a non-irrigated control). After 50 d of irrigation treatments, leaf water potential was −1.70, −2.34, −2.48, −2.89, −3.55, and −4.92 MPa for treatment T1, T2, T3, T4, T5, and control, respectively. Leaf biomass yield increased by 32.8%, 21.9%, and 21.3% for T1, T2, and T3, respectively, compared to control. The net photosynthesis (Pn), stomatal conductance (gs) and transpiration (E) decreased with irrigation interval increasing. Tea polyphenol (TP) and free amino acid (AA) decreased when the irrigation intervals were increased, but caffeine (CA) content apparently increased as the irrigation intervals were increased. To balance irrigation water demand and tea yield and quality, it is recommended that the irrigation interval should be set at 10 d with a rate of 3.5 kg water per plant for the optimal production in Anxi, Fujian province of China.  相似文献   

12.
Field experiments were carried out to investigate water and salt management and its effects on Leymus chinensis growth under drip irrigation on saline-sodic soils of the Songnen Plain, China. The ECe of the experiment soil here is 15.2 dS/m and SARe is 14.6 (mmolc L−1)1/2. The threshold of soil matric potential (SMP) was preset in different treatments (−5, −10, −15, −20 and −25 kPa) to control the timing of the irrigation cycle using vacuum tensiometers buried at 0.2 m depth immediately under drip emitters. Drip irrigation frequency and soil matric potential significantly influenced water and salt distributions and L. chinensis growth. In the root zone, the soil water content increased with the SMP, but at deeper layers there were no significant differences in soil water content due to the effect of groundwater. Electrical conductivity showed that there was a low-salt zone near the emitters and that drip irrigation inhibited the buildup of salts in the root zone. There was more leaching of salts for −5 and −10 kPa treatments than for the −15, −20 and −25 kPa treatments. After two years of drip irrigation, the surface salts were well leached, and had moved down with the water to depths below 40 cm. The pH of each treatment was a little decreased and the soil nutrient of S1-S5 were all increased after reclamation, but there were no obvious differences of the five treatments. The best growth was achieved with soil matric potentials of −5 and −10 kPa: the plant height, number and length of spikes, number of tillers, coverage and aboveground biomass all attained their maximum values during the growth periods of L. chinensis, with no significant differences between those two treatments. Thus, in the Songnen Plain, drip irrigation can be used on transplanted L. chinensis for restoration of saline-sodic soils. The results provide theoretical and technological guidance for sustainable reclamation salt-affected soil and the quick restoration and reconstruction of saline-sodic grassland.  相似文献   

13.
Irrigation performance assessments are required for hydrological planning and as a first step to improve water management. The objective of this work was to assess seasonal on-farm irrigation performance in the Ebro basin of Spain (0.8 million ha of irrigated land). The study was designed to address the differences between crops and irrigation systems using irrigation district data. Information was only available in districts located in large irrigation projects, accounting for 58% of the irrigated area in the basin. A total of 1617 records of plot water application (covering 10,475 ha) were obtained in the basin. Average net irrigation requirements (IRn) ranged from 2683 m3 ha−1 in regulated deficit irrigation (RDI) vineyards to 9517 m3 ha−1 in rice. Average irrigation water application ranged from 1491 m3 ha−1 in vineyards to 11,404 m3 ha−1 in rice. The annual relative irrigation supply index (ARIS) showed an overall average of 1.08. Variability in ARIS was large, with an overall standard deviation of 0.40. Crop ARIS ranged between 0.46 and 1.30. Regarding irrigation systems, surface, solid-set sprinkler and drip irrigated plots presented average ARIS values of 1.41, 1.16 and 0.65, respectively. Technical and economic water productivities were determined for the main crops and irrigation systems in the Aragón region. Rice and sunflower showed the lowest productivities. Under the local technological and economic constraints, farmers use water cautiously and obtain reasonable (yet very variable) productivities.  相似文献   

14.
The increasing cost and scarcity of water for irrigation is placing pressure on Australian dairy farmers to utilize water more efficiently, and as result, water use efficiency (WUE) of forages is becoming an important criterion for sustainable dairy production. This study was conducted to identify more water use efficient forage species than the dominant dairy forage, perennial ryegrass (Lolium perenne L.). Seventeen annual forage species were investigated under optimum irrigation (I1) and two deficit irrigation treatments (nominally 66 and 33% of irrigation water applied to the optimal level), over 3 years at Camden, NSW, on a brown Dermsol in a warm temperate climate. Forages with the highest yield generally had the highest WUEt (total yield/evapotranspiration). Under optimal irrigation, there was a three-fold difference in mean annual WUEt between forages, with maize (Zea mays L.) having the highest (42.9 kg ha−1 mm−1) and cowpea (Vigna unguiculata (L.) Walp.) the lowest (13.5 kg ha−1 mm−1), with 11 of the forage species having a greater WUEt than perennial ryegrass. The ‘harvested’ forages maize, wheat, triticale (Triticosecale rimpaui Wittm.) and maple pea (Pisum sativium L.) generally had higher mean WUEt (26.7-42.9 kg ha−1 mm−1) than the remaining forages which were defoliated multiple times to simulate grazing (13.5-30.1 kg ha−1 mm−1). The reduction in annual WUEt in response to deficit irrigation was greatest for the warm season forages with up to 30% reduction for maize, while most of the cool season annuals were not significantly affected by deficit irrigation at the levels imposed. In order to maximize WUEt of any forage, it is necessary to maximize yield, as there is a strong positive relationship between yield and WUEt. However, while WUEt is an important criterion for choosing dairy forages, it is only one factor in a complex system. Choice of forages must be considered on a whole farm basis and include consideration of yield, nutritive value, cost of production and risk.  相似文献   

15.
The development of different tools to evaluate the performance of Water Users Associations (WUAs) is an important practice for improving water and energy management, together with other production costs. One of these tools is the Benchmarking technique, which is based on the comparison between different WUAs to determine the best practices in each of them.In this paper, a Benchmarking process is applied to seven WUAs located in Castilla-La Mancha (Spain) during three irrigation seasons (2006-2008). The performance indicators developed by the International Programme for Technology and Research in Irrigation and Drainage (IPTRID) are used, while new indicators dealing with production and energy are proposed. The goals of this paper are to group WUAs with the same characteristics, using performance and energy indicators, and to reduce the set of indicators using statistical methods. The most important indicators, easy to obtain and yielding result in maximum information are retained for further use.Three proposals reducing the initial number of indicators were proposed, with an aim of being useful for future applications based on characterizing WUAs. Indicators results highlighted that irrigable areas can be grouped based on the application of drip irrigation systems and those with sprinkler irrigation systems. When using groundwater resources, no significant differences were observed for energy consumption between these irrigation systems. This can be explained by the indicator energy load index (ICE, m), which had similar values in all WUAs analyzed. According to annual irrigation water supply per unit irrigated area (VTSr, m3 ha−1), the highest values (between 5200 m3 ha−1 and 6800 m3 ha−1) were obtained in WUAs with sprinkler irrigation systems, which contained crops characterized by high water requirements, compared to the VTSr (less than 1800 m3 ha−1) of WUAs with drip irrigation systems, with crops that required less volume of irrigation water. Regarding production efficiency indicators, in drip irrigation systems the high presence of vineyards, almond and olive trees, crops with low water requirements, explained high values of gross margin per unit irrigation delivery (MBVs, € m−3)(close to 0.82 € m−3) in comparison with sprinkler irrigation systems (close to 0.36 € m−3).  相似文献   

16.
Decreasing in water availability for cotton production has forced researchers to focus on increasing water use efficiency by improving either new drought-tolerant cotton varieties or water management. A field trial was conducted to observe the effects of different drip irrigation regimes on water use efficiencies (WUE) and fiber quality parameters produced from N-84 cotton variety in the Aegean region of Turkey during 2004 and 2005. Treatments were designated as full irrigation (T100, which received 100% of the soil water depletion) and those that received 75, 50 and 25% of the amount received by treatment T100 on the same day (treatments T75; T50 and T25, respectively). The average seasonal water use values ranged from 265 to 753 mm and the average seed cotton yield varied from 2550 to 5760 kg ha−1. Largest average cotton yield was obtained from the full irrigation treatment (T100). WUE ranged from 0.77 kg m−3 in the T100 to 0.98 kg m−3 in the T25 in 2004 growing season and ranged from 0.76 kg m−3 in the T100 to 0.94 kg m−3 in the T25 in 2005 growing season. The largest irrigation water use efficiency (IWUE) was observed in the T25 (1.46 kg m−3), and the smallest IWUE was in the T100 treatment (0.81 kg m−3) in the experimental years. A yield response factor (ky) value of 0.78 was determined based on averages of two years. Leaf area index (LAI) and dry matter yields (DM) increased with increasing water use for treatments. Fiber qualities were influenced by drip irrigation levels in both years. The results revealed that well-irrigated treatments (T100) could be used for the semi-arid climatic conditions under no water shortage. Moreover, the results also demonstrated that irrigation of cotton with drip irrigation method at 75% level (T75) had significant benefits in terms of saved irrigation water and large WUE indicating a definitive advantage of deficit irrigation under limited water supply conditions. In an economic viewpoint, 25.0% saving in irrigation water (T75) resulted in 34.0% reduction in the net income. However, the net income of the T100 treatment is found to be reasonable in areas with no water shortage.  相似文献   

17.
The increasing scarcity of water for irrigation is becoming the most important problem for producing forage in all arid and semi-arid regions. Pearl millet is a key crop in these regions which needs relatively less water than other crops. In this research, a field study was conducted to identify the best combination of irrigation and nitrogen (N) management to achieve acceptable pearl millet forage both in quantity and quality aspects. Pearl millet was subjected to four irrigation treatments with interaction of N fertilizer (0, 75, 150 and 225 kg ha−1). The irrigation treatments were 40%, 60%, 80% and 100% of total available soil water (I40, I60, I80 and I100, respectively). The results showed that increasing moisture stress (from I40 to I100) resulted in progressively less total dry matter (TDM), leaf area index (LAI), and nitrogen utilization efficiency (NUzE), while water use efficiency (WUE) and the percentage of crude protein (CP%) increased. The highest TDM and LAI were found to be 21.45 t ha−1 and 8.65, in I40 treatment, respectively. TDM, WUE, CP% and profit responses to N rates were positive. The maximum WUE of 4.19 kg DM/m3 was achieved at I100 with 150 kg N ha−1. The results of this research indicate that the maximum profit of forage production was obtained in plots which were fully irrigated (I40) and received 225 kg N ha−1. However, in the situation which water is often limited and not available, application of 150 kg N ha−1 can produce high forage quality and guaranty acceptable benefits for farmers.  相似文献   

18.
A field study on cotton (Gossypium hirsutum L., cv.) was carried out from 2005 to 2008 in the Çukurova Region, Eastern Mediterranean, Turkey. Treatments were designated as I100 full irrigation; DI70, DI50 and DI00 which received 70, 50, and 0% of the irrigation water amount applied in the I100 treatment. The irrigation water amount to be applied to the plots was calculated using cumulative pan evaporation that occurred during the irrigation intervals. The effect of water deficit or water stress on crop yield and some plant growth parameters such as yield response, water use efficiencies, dry matter yield (DM), leaf area index (LAI) as well as on lint quality components was evaluated. The average seasonal evapotranspiration ranged from 287 ± 15 (DI00) to 584 ± 80 mm (I100). Deficit irrigation significantly affected crop yield and all yield components considered in this study. The average seed cotton yield varied from 1369 ± 197 (DI00) to 3397 ± 508 kg ha−1 (I100). The average water use efficiency (WUEET) ranged from 6.0 ± 1.6 (I100) to 4.8 ± 0.9 kg ha−1 mm−1 (DI00), while average irrigation water use efficiency (WUEI) was between 9.4 ± 3.0 (I100) and 14.4 ± 4.8 kg ha−1 mm−1 (DI50). Deficit irrigation increased the harvest index (HI) values from 0.26 ± 0.054 (I100) to 0.32 ± 0.052 kg kg−1 (DI50). Yield response factor (Ky) was determined to be 0.98 based on four-year average. Leaf area index (LAI) and dry matter yields (DM) increased with increasing water use. This study demonstrated that the full irrigated treatment (I100) should be used for semiarid conditions with no water shortage. However, DI70 treatment needs to be considered as a viable alternative for the development of reduced irrigation strategies in semiarid regions where irrigation water supplies are limited.  相似文献   

19.
This study compares the effects of different irrigation regimes on seed yield and oil yield quality and water productivity of sprinkler and drip irrigated sunflower (Helianthus annus L.) on silty-clay-loam soils in 2006 and 2007 in the Mediterranean region of Turkey. In sprinkler irrigation a line-source system was used in order to create gradually varying irrigation levels. Irrigation regimes consisted of full irrigation (I1) and three deficit irrigation treatments (I2, I3 and I4), and rain-fed treatment (I5). In the drip system, irrigation regimes included full irrigation (FI-100), three deficit irrigation treatments (DI-25, DI-50, DI-75), partial root zone drying (PRD-50) and rain-fed treatment (RF). Irrigations were scheduled at weekly intervals both in sprinkler and drip irrigation, based on soil water depletion within a 0.90 m root zone in FI-100 and I1 plots. Irrigation treatments influenced significantly (P < 0.01) sunflower seed and oil yields, and oil quality both with sprinkler and drip systems. Seed yields decreased with increasing water stress levels under drip and sprinkler irrigation in both experimental years. Seed yield response to irrigation varied considerably due to differences in soil water contents and spring rainfall distribution in the experimental years. Although PRD-50 received about 36% less irrigation water as compared to FI-100, sunflower yield was reduced by an average of 15%. PRD-50 produced greater seed and oil yields than DI-50 in the drip irrigation system. Yield reduction was mainly due to less number of seeds per head and lower seed mass. Soil water deficits significantly reduced crop evapotranspiration (ET), which mainly depends on irrigation amounts. Significant linear relationships (R2 = 0.96) between ET and oil yield (Y) were obtained in each season. The seed yield response factors (kyseed) were 1.24 and 0.86 for the sprinkler and 1.19 and 1.06 for the drip system in 2006 and 2007, respectively. The oil yield response factor (kyoil) for sunflower was found to be 1.08 and 1.49 for both growing seasons for the sprinkler and 1.36 and 1.25 for the drip systems, respectively. Oil content decreased with decreasing irrigation amount. Consistently greater values of oil content were obtained from the full irrigation treatment plots. The saturated (palmitic and stearic acid) and unsaturated (oleic and linoleic acid) fatty acid contents were significantly affected by water stress. Water stress caused an increase in oleic acid with a decrease in linoleic acid contents. The palmitic and stearic acid concentrations decreased under drought conditions. Water productivity (WP) values were significantly affected by irrigation amounts and ranged from 0.40 to 0.71 kg m−3 in 2006, and from 0.69 to 0.91 kg m−3 in 2007. The PRD-50 treatment resulted in the greatest WP (1.0 kg m−3) and irrigation water productivity (IWP) (1.4 kg m−3) in both growing seasons. The results revealed that under water scarcity situation, PRD-50 in drip and I2 in sprinkler system provide acceptable irrigation strategies to increase sunflower yield and quality.  相似文献   

20.
Florida is the largest producer of fresh-market tomatoes in the United States. Production areas are typically intensively managed with high inputs of fertilizer and irrigation. The objectives of this 3-year field study were to evaluate the interaction between N-fertilizer rates and irrigation scheduling on yield, irrigation water use efficiency (iWUE) and root distribution of tomato cultivated in a plastic mulched/drip irrigated production systems. Experimental treatments included three irrigation scheduling regimes and three N-rates (176, 220 and 230 kg ha−1). Irrigation treatments included were: (1) SUR (surface drip irrigation) both irrigation and fertigation line placed right underneath the plastic mulch; (2) SDI (subsurface drip irrigation) where the irrigation line was placed 0.15 m below the fertigation line which was located on top of the bed; and (3) TIME (conventional control) with irrigation and fertigation lines placed as in SUR and irrigation being applied once a day. Except for the “TIME” treatment all irrigation treatments were controlled by soil moisture sensor (SMS)-based irrigation set at 10% volumetric water content which was allotted five irrigation windows daily and bypassed events if the soil water content exceeded the established threshold. Average marketable fruit yields were 28, 56 and 79 Mg ha−1 for years 1-3, respectively. The SUR treatment required 15-51% less irrigation water when compared to TIME treatments, while the reductions in irrigation water use for SDI were 7-29%. Tomato yield was 11-80% higher for the SUR and SDI treatments than TIME where as N-rate did not affect yield. Root concentration was greatest in the vicinity of the irrigation and fertigation drip lines for all irrigation treatments. At the beginning of reproductive phase about 70-75% of the total root length density (RLD) was concentrated in the 0-15 cm soil layer while 15-20% of the roots were found in the 15-30 cm layer. Corresponding RLD distribution values during the reproductive phase were 68% and 22%, respectively. Root distribution in the soil profile thus appears to be mainly driven by development stage, soil moisture and nutrient availability. It is concluded that use of SDI and SMS-based systems consistently increased tomato yields while greatly improving irrigation water use efficiency and thereby reduced both irrigation water use and potential N leaching.  相似文献   

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