Drip Irrigation Water Research Articles

Assessing governance of irrigation systems: A view from below

Attempts at irrigation development in Ghana, as in many other parts of sub-Saharan Africa, have been characterized by governance challenges at various levels. This paper aims to provide an empirical assessment of irrigation governance in 37 small-scale irrigation schemes in northern Ghana, derived from the perceptions of their users. We first distinguish six dimensions of governance based on the available literature to include participation, accountability, conflict management, transparency and cooperation, equity and fairness, and sustainable use. Next, we measure these irrigation governance dimensions using ratings provided by local water users. We then examine the relationship between these governance measures and some objective factors that possibly drive the assessments of users. The results indicate an overall good governance in the sampled schemes. Relatively, sustainable use had the lowest score and conflict management had the highest score. We further find that in schemes located in areas with relatively high annual precipitations, users report better irrigation governance. Within schemes, both users with plots at the head end and users with plots at the tail end are more critical about irrigation governance than other users. Remarkably, the number of users of a scheme has no significant effect on their overall assessment of its governance, although users in larger schemes are more positive on opportunities to participate in governance bodies and to keep these bodies accountable. To improve their sustainability, small-scale irrigation schemes (dams) may be better maintained for domestic and livestock watering. Promoting water-conserving irrigation techniques such as drip irrigation and ground water techniques is essential.

INNOVATIONS IN IRRIGATION SYSTEMS IN AFRICA†

INNOVATIONS IN IRRIGATION SYSTEMS IN AFRICA^†

Using phosphate fertilizer to reduce emitter clogging of drip fertigation systems with high salinity water

Phosphorous (P) fertigation with high salinity water (HSW) drip irrigation would be an effective measure to relieve soil and water pollution caused by the excessive application of P fertilizer, and achieve synergistic saving of both limited fresh water and non-renewable P resources. However, the emitter clogging issues of drip fertigation systems seriously restricts the utilization of this technology. This study proposes an approach to reduce emitter clogging in HSW drip fertigation systems by choosing the appropriate type and concentration of P fertilizer. The effects of two new types of P fertilizers (ammonium polyphosphate, APP; urea phosphate, UP), and a traditional P fertilizer (monopotassium phosphate, MKP), were assessed at three fertilization concentrations (0, 0.15, and 0.30 g/L) on the clogging behavior of four types flat emitters. The results indicated that the application of MKP aggravated the clogging of emitters in comparison with non-fertilization. While the addition of two new types of P fertilizers (APP and UP) effectively alleviated emitters clogging (the irrigation uniformity of systems increased by 26.2%–74.6%) by inhibiting the formation of carbonate, although precipitation of phosphate, silicate, and quartz increased. Moreover, under the equal application amount of P fertilizer, UP and APP were more effective in relieving clogged when applied at a low-concentration with long-term running and high-concentration with short-term running mode. The results could pave a way for reducing the pollution in agricultural production and conserving freshwater and non-renewable P resources.

Effect of different water quality parameters on acid requirement to lower the PH of water in drip irrigation

Drip irrigation system has been widely used as an efficient application method. But performance of a drip irrigation system using poor quality water is mainly limited by emitter clogging and this discourages farmers to use drip irrigation system as emitter clogging reduce irrigation efficiency. This paper gives the result of laboratory study conducted to determine the amount of acid required to lower pH of water to desired level to prevent emitter clogging. Three ground samples of different pH and chemical composition were used. Three acid HCL (36.5%conc) H2SO4 (98.08% conc.) and H3PO4 (88% conc.) were used to bring the pH to 4.0. Amount of acid required depends on strength of acid used, buffering capacity of irrigation water, pH of irrigation water and on target pH of water. Functional relationships are developed to determine the amount of different acids required per 1000 litre of water.

Effect of irrigation and fertilization regimes on grain yield, water and nitrogen productivity of mulching cultivated maize (Zea mays L.) in the Hetao Irrigation District of China

Irrigation and fertilizer management are essential for sustainable development of agriculture in the arid and semiarid regions. In order to obtain high yield production, over irrigation and fertilization are frequently conducted by the farmer which results in a series of environmental problems in particular in the shallow groundwater areas. In this paper, two-year field experiments were conducted to investigate the effect of irrigation and fertilization regimes on grain yield, water and nitrogen productivity of mulching cultivated maize (Zea mays L.) in the Hetao Irrigation District of China. Two irrigation methods, i.e., drip and border irrigation, with different schedules were manipulated in silt loam soil. The border irrigation included two/three different water levels and drip irrigation was triggered by a tensiometer located at a depth of 25 cm with different matric potentials (−15, −25 and −35 kPa). Three different nitrogen fertilization levels (350, 250 and 150 kg ha−1) were applied under drip irrigation controlled by the matric potential of −25 kPa. Soil water storage variation indicated that the active root zone concentrated at a depth of 35−60 cm in the border irrigated plots and 25−45 cm in the drip irrigated plots. Around 16 % of irrigated water (71 out of 450 mm) and 18 % of supplied nitrogen fertilizer (64 out of 350 kg ha−1) were percolated into deeper zone for the farmer’s irrigation and fertilization schedules. Border irrigation water reduced from 450 to 315 mm could decrease the deep percolation without yield reduction. Almost no deep percolation was detected in drip irrigation for three different matric potential controls. The highest yield, water and nitrogen productivity obtained from the drip irrigated plots triggered by matric potential of −15 kPa. Considering yield, water and nitrogen productivity, environmental factors and farmer’s net-profit, drip irrigation at the matric potential of −15 kPa with 250 kg ha−1 nitrogen fertilizer or border irrigation of 315 mm is recommended for mulching cultivated maize in silt loam soil in the Hetao Irrigation District. The nitrogen fertilizer schedule in border irrigation is desirable for optimal application.

Effect of Buried Straw Layer Coupled with Fertigation on Florescence and Yield Parameters of Chinese Cabbage Under Greenhouse Environment

Inefficient and over usage of chemical fertilizer and irrigation water have been a severe worry with an adversative environmental and economic effects in China. The experiments were conducted on Chinese cabbage for two consecutive seasons to investigate the effects of coupling fertigation with buried straw layer on crop florescence and yield parameters of Chinese cabbage (Brassica rapa L. chinensis) under greenhouse environment. The three factors randomized complete block design was applied having two levels each: (straw layer: S−, no straw; and S+, having buried straw layer, fertilizer: NH, 120 kg ha−1; and NL, 80 kg ha−1; and drip irrigation water: W50, 50%; and W30, 30% of evapotranspiration (ETO) with irrigation frequency of two days). The three-way ANOVA indicated that T4 (S+NLW30) and T5 (S−NHW50) gave higher values of maximum quantum yield (Fv/Fm), maximum electron transport rate (ETRmax), and chlorophyll content (Chl) which ultimately affected the fresh crop yield positively under these treatments when compared with all other treatments. The maximum values of plant dry biomass and roots dry biomass were also achieved under T4 (S+NLW30) and T5 (S−NHW50) treatments when compared with the other treatments. Although T4 and T5 have no significant difference in florescence and yield parameters but T4 saved 14–23% water and 33% nitrogen fertilizer. Therefore, T4 could be adopted as a strategy to manage water and nitrogen fertilizer for optimum growth of Chinese cabbage.

Modeling the transfer of potassium monophosphate with irrigation water in drip irrigation and sprinkling

Fertigation practically always allows us to simultaneously solve a wide range of problems of supplying plants with mineral substances. It is due to the possibility to localize the application area in accordance with the structural features of the root system of the plant. A review of the studies on modeling and calculating the transfer of nutrients shows that spatial inhomogeneity of nutrients distribution may lead to their excess in wrong soil areas. Time intervals and volumes of applying dissolved fertilizers determine the not yet completely studied dynamics of concentration of the nutrition elements in the root area. Formation of the root system is under a strong influence of the boundaries of the wetting contour, since after the irrigation and soil drying nutrients tend to concentrate in this particular area. The results of transfer modeling showed significant differences in the final distribution of potassium monophosphate in soil depending on the initial distribution of moisture there. This can be pre-estimated and calculated. The designed software programme for modeling nutrients transfer with irrigation water allows the user to set various initial wetting gradients depending on the depth, the intervals between the drippers, the intensity and duration of watering. The calculations are made considering the basic hydrophysical soil characteristic and hydraulic conductivity function. The software is equipped with an interactive graphic interface for primary data processing, soil profile discretization and graphic representation of the results.

Simulation of Water and Salt Transport in Soil under Pipe Drainage and Drip Irrigation Conditions in Xinjiang

With the popularization and development of drip irrigation under film, the problem of secondary soil salinization in Xinjiang is becoming more and more serious. To explore water and salt transport in drip irrigation under mulch and drainpipe drainage, drainage tests of drainage ditches in saline-alkali soil in the Xinjiang 112 group were used to monitor soil salinity changes by controlling field irrigation. Then, a HYDRUS (PC-Progress, Prague, Czech Republic) numerical model was used to simulate and analyze the changes in salinity during cotton growth and the autumn salt return stage in saline-alkali soil under drainage conditions. The agreement between the simulated and measured values was high, and the model parameters were reliable. During the growth period of cotton, the salinity continued to decrease, and the salt began to return after the harvest. Compared with before planting, in the 0–80 cm soil layer, the average desalinization rate reached 43.52% under the mulching films, and the average desalinization rate reached 13.83% under and between the mulching films. After the cotton was harvested, salt returned to the upper layer of soil. However, it still showed a decrease compared with the level before sowing. The average salt content of 0–80 cm soil decreased by 5.14%, and the average salt content of 0–200 cm decreased by 2.60%. This shows that the total salt content in soil will continue to decrease after long-term use of drip irrigation and underground pipe drainage.

Straw Mulching under a Drip Irrigation System Improves Maize Grain Yield and Water Use Efficiency

ABSTRACTReasonable use of water is required for the sustainable development of maize production in the North China Plain (NCP). In this study, straw mulching (SM) was evaluated in a 2‐yr field experiment to determine whether its effect on maize (Zea mays L.) yield and water use efficiency (WUE) differed under different irrigation systems. Compared with no mulching (NM) treatment, SM increased maize yield by 10.6 and 12.5% under a drip irrigation system in 2016 and 2017, respectively, which was mainly attributed to an 11.7 and 13.5% increase in total dry matter (DM). The increased soil water content in the 0‐ to 40‐cm layer at the six‐leaf (V6), silking (R1), and maturity (R6) stages for SM improved the soil mineral N content (Nmin) in that layer and then increased the N accumulation from V6 to R1 and post‐silking by 7.6 and 21.1% averaged over 2 yr compared with NM, respectively. The enhanced N accumulation for SM increased the leaf area index and DM accumulation rate, which increased the DM accumulation from V12 to R1 and post‐silking by 16.2 and 16.4% averaged over 2 yr compared with NM, respectively, and then the grain number and grain weight. Straw mulching also improved the WUE under the drip irrigation system due to the greater grain yield and 6.1% lower water consumption. This demonstrated that SM combined with the drip irrigation system effectively improved the yield and WUE of maize due to improved DM and N accumulation promoted by the increased water content and Nmin in the upper soil layers.

Toothpick method to evaluate soil antagonism against the white root rot fungus, Rosellinia necatrix

A method was developed to evaluate soil antagonism against the white root rot fungus, Rosellinia necatrix. Toothpicks colonized by the fungus were immersed into hot water to produce an extinction zone (EZ) of the fungus and then inserted into soil from different orchards. The EZ differed to various extents in unsterile soils; however, when soil was sterilized, the EZ disappeared. Using this method, we investigated the mechanism of the hot water drip irrigation method devised to control white root rot. The results showed the involvement of synergism between hot water and soil antagonists in the control measure against R. necatrix.

Synergistic responses of drip-irrigated wheat crop to chitosan and/or silicon under different irrigation regimes

Water scarcity is considered as a key restriction for food production worldwide. Chitosan (Chi) and silicon (Si) play a crucial role in plants metabolic processes under normal or stress conditions. Field experiments were done at the Res. Station, Nat. Res. Cen., El-Nubaria Province, Egypt, in 2014/15 and 2015/16 seasons in a split-plot based on randomized complete block design with three replications, for assessing the defensive role of Chi and/or Si on wheat growth, yield, some physio-anatomical attributes and water use efficiency under different irrigation regimes. The experimental treatments included three irrigation water regimes (100, 70, and 40% of drip irrigation water requirement "IWR") as the main factor, as well as Chi and/or Si (water, 125 mg L−1 Si, 250 mg L−1 Chi, and 125 mg L−1 Si+250 mg L−1 Chi) as the sub-factor.Water deficit significantly decreases plant growth, yield, photosynthetic pigment, and relative water content; whereas significantly induced noticeable changes in leaf and stem anatomy as well as organelle's ultrastructure. Application of Chi + Si gave the highest plant growth and yield attributes, maintaining plant water status, along with improved physiological trials under irrigation regimes. Additionally, the application of Chi + Si under severe drought showed an ameliorative effect on cell ultrastructure compared with drought-affected plants only including well-developed chloroplasts, increased plastoglobules and maintained nucleus and mitochondria structure.Overall, this investigation proposes that the application of 125 mg L−1 Si plus 250 mg L−1 Chi twice at 50 and 70 days from sowing had potential to mitigate the water deficit effects, improving water use efficiency as well as increasing the wheat yield and its quality.

Effects of mixing Yellow River water with brackish water on the emitter’s clogging substance and solid particles in drip irrigation

The water shortage and soil salinization have become a great challenge for the Yellow River irrigation area. Mixing Yellow River water with brackish water for drip irrigation can be an effective solution because of the mixed water contents less sediment and salinity. However, the mixed water can still cause emitter’s clogging and significantly reduce drip irrigation system performance. In order to find out a proper method of relieving the emitter’s clogging in drip irrigation and increase the efficiency of irrigation water utilization, three different types of water including the Yellow River water, brackish water, and mixed water of Yellow River water and brackish water at the mixing ratio of 1:1 were used to cultivate the emitter’s clogging substance. The results showed that the clogging substance growth is a “S-curve.” The mixing of Yellow River water (YR) and brackish water (BW) can mitigate the formation of the clogging substance as the dry weight on mixed water was 6.07 mg/cm2, which was 47.38–65.71% less than YR and 26.53–47.40% less than BW. Moreover, the Si deposit had significant effect on the clogging substance in the condition of YR and the Ca/Mg deposit had significant effect on the clogging substance in the condition of BW. There was no deposit that had significant effect on the clogging substance in the mixed water. The contents of sediment and ions were reduced significantly after mixing Yellow River water and brackish water. The result can be helpful to facilitate utilization of brackish water in Yellow River irrigation area.

EFFECT OF IRRIGATION WATER SALINITY ON SWEET PEPPER YIELD AND ITS WATER PRODUCTIVITY UNDER DRIP IRRIGATION

Availability of fresh surface water for irrigation is declining in Egypt and saline ground water is increasingly used for irrigation. A field experiment was carried out on a sandy soil at Dokki protected cultivation experimental site, Agriculture Research Center (ARC), Ministry of Agriculture and Land Reclamation during summer and winter season of 2017-2018, to evaluate the effect of water quality and drip irrigation management on sweet pepper ( Capsicum annuum L. cv. Top star) plants under surface drip irrigation. The experiment consists of three treatments of water salinity (EC) with and without adding the needed leaching requirements (LR). The water salinity treatments were the control (Sc) where EC = 0.4ds/m, (S3ds/m) where EC = 3ds/m and (S5ds/m) where EC = 5ds/m, leaching requirement (LR) was applied after 2 months from transplanting. LR treatments were ScLR; S3LR and S5LR. It was found that irrigation with different salinity levels and Leaching requirement both affected the growth characteristics, yield and irrigation water productivity of sweet pepper plant. It was concluded that more salt accumulation in the root zone could lead to higher potential yield losses of sensitive and moderately sensitive crops, such as sweet peppers. Also, it was found that the higher the salinity in the irrigation water the less the plant height, the roots fresh weight, and the number of fruits per plant. As well as the higher the salinity in the irrigation water the more concentration of Na, cl, TSS and proline in fruits. It was observed that the highest peppers yield (2.89 Kg/m2) and the best irrigation water productivity (1.04 Kg/m3 water) were obtained from the fresh water treatment with LR management (ScLR). While, irrigation by saline water with LR S3LR and S5LR treatments reduced peppers yield by 19% and 66% compared with Sc respectively.

Automatic drip irrigation scheduling effects on yield and water productivity of banana

Water scarcity is one of the major factors affecting the productivity of banana. Drip irrigation (DI) has been found as a water saving technique in banana cultivation. Further, sensor-based automated DI which has been considered as a smart and real time water application technique might increase the water savings and enhance yield of banana. With this hypothesis, a field experiment was conducted to study the performance of automated DI in banana (cv. Grand Naine) at Bhubaneswar, India during 2016–2017. Five automated DI schedules: (i) soil water sensor-based irrigation (I1) and timer based irrigation (ii) at 1 h interval 3 times daily at 80% crop evapotranspiration (ETc) (I2), (iii) at 2 h interval 2 times daily at 80% ETc (I3), (iv) at 1 h interval 3 times daily at 60% ETc (I4) and (v) at 2 h interval 2 times daily at 60% ETc (I5) were compared with manually operated DI at 100% ETc (I6) in the crop. The highest vegetative growth of plants (plant height, canopy diameter, stem girth) was observed with manually operated DI. However, sensor-based DI produced 15% higher fruit yield with 20% water saving, resulting in 40% higher water productivity (yield per unit quantity of water) compared with manually operated DI (water used, 820 mm; yield, 60.5 t ha−1; water productivity, 6.2 kg m−3) in the crop. The fruit qualities (total soluble solids and acidity) of sensor-based irrigated plants were superior to manually irrigated plants. The volumetric soil water content under manual DI was marginally higher (11–15%) than that under sensor-based DI (21.2–24.8%). The soil available nutrients (N, P and K) and leaf nutrients content of the plants followed the similar trend of soil water content under different treatments. The yield forecasting based on leaf-N, leaf-K, leaf water content and radiation interception using ‘Principal component analysis’ performed well with reasonably accuracy (R2 = 0.82). Overall, these results reveal that soil water sensor-based automated DI is a productive and water saving technique which may be adopted in banana cultivation in eastern India and anywhere else with similar agro-climates of the study site.

Health evaluation on migration and distribution of heavy metal Cd after reclaimed water drip irrigation.

The utilization of reclaimed water is one of the effective measures to save water resources. The study of reclaimed water irrigation and the analysis of how heavy metals migrate in the soil, especially their movement laws, have important theoretical and practical significance. It helps to predict the risk of heavy metals in foods, which protects our health and safety. In this paper, we studied the accumulation and distribution of heavy metal Cd in soils with reclaimed water drip irrigation in greenhouses during growing season, comparing the effects with groundwater drip irrigation. The results show that the Cd concentration in the surface soil is the highest on the second day after drip irrigation. It will be the highest on the fourth day in the depth of 100cm, and then, it will decrease slightly. During the period of the sixth day to the eighth day, the Cd concentrations are similar in each depth, and it is the highest in the depth of 0-40cm and 80-120cm, but the Cd concentration decreases with the lower depth below 120cm. By utilizing proper ways of reclaimed water drip irrigation, the Cd concentration in the deep soil will not violate the standard limits of GB15618-1995, which will not cause Cd pollution.

Biomass Production and Carbon Sequestration by Cultivation of Trees under Hyperarid Conditions using Desalinated Seawater (Sewage Water)

As growing economies – in particular in the Gulf region – use extreme and growing amounts of desalinated seawater for municipal purposes the use of produced waste waters is in the focus of science. The fixation of atmospheric carbon-dioxide by a safe cultivation of trees using this slightly salty water sources is of increased importance in times of ongoing climate change. Unfortunately, existing research relies on irrigation of trees in arid lands using ground water, any kind of precipitation, seasonal events like river flooding or a mix of them. To date no data support the biomass or tree production in total absence of natural precipitation and complete lack of ground water. In this study, seven timber and fuelwood tree species, namely, Eucalyptus occidentalis En., Eucalyptus tereticornis Smith, Eucalyptus camaldulensis Dehnh., Eucalyptus gomphocephala DC., Eucalyptus grandis Hybr. Hill ex Maid, Tamarix aphylla (L.) Karst., Tamarix nilotica (Ehrenb.) Bunge were tested for carbon sequestration and biomass-production. Above-soil and sub-soil parts were determined under two levels of drip-irrigation water supply: 25% and 50% of Evapotranspiration (ETo) over a period of two years and four months from planting to harvest. The trees were cultivated under hyper-arid climatic conditions using brackish irrigation water (3.5 dS m-1) on a research and development station in Arava, Israel. Purified waste water from a seawater desalination plant (reverse osmosis) was applied after municipal use. Eucalyptus gomphocephala DC. delivered the highest yields and had the highest water use efficiency, producing 70 t of Dry Matter (DM) /ha/a under the higher irrigation level. Compared with the other species, E. gomphocephala DC. showed a 32% to 65% superior performance . Whereas, lower amounts of saline irrigation water were favoured by E. camaldulensis and T. aphylla – both producing more than 50 t of DM/ha/a. Nevertheless, Tamarix, as a halophyte specialist plant, needed 30 % less water for this growth. Both Eucalyptus varieties mentioned before form a closed tree stand and reached a height of almost 10 m, two years after planting. Regardless of the particular use of the produced timber, about 15 – 25% of the trees’ total DM, approximately equal to the carbon-content, remains in the soil as long-term carbon-storage after harvesting the above ground biomass. Fast growing fuelwood tree species ensure a safe long-term biological fixation of carbon Irrigated with small amounts of saline waste water.

Assesment of water productivity using different drip irrigation systems for cotton

The aim of this study is to evaluate water productivity (WP), economic water productivity (EWP) and land economic productivity (LEP) using different amount of irrigation water and different drip irrigation (surface drip irrigation, SDI) and subsurface drip irrigation, SSDI) for cotton. For that, the results of the experiment carried out in cotton growing season of 2016 and 2017 were evaluated. The maximum WPIrrig (0.84 kg m−3) occurred in the SSDI system at the lateral pipe depth of 40 cm. However, the net LEP (US$1109.9 ha−1) was in which the irrigation application (551.3 mm) had a calculated crop water requirement of 1.00 times using Penman-Monteith method. The maximum EWP (US$0.19 m−3) occurred also in the SSDI system with the lateral pipe depth of 40 cm. SSDI under the depth of 40 cm resulted in reducing water use and greater water productivity using an amount of irrigation water based on 1.0xCrop water requirement. Thus, this treatment was found to be more applicable in terms of farmer practices. WPIng, WP, EWP and LEP should be considered jointly for an optimization of water productivity and water saving in terms of farmers and irrigation schemes.

Multi-objective optimization of water and fertilizer management for potato production in sandy areas of northern China based on TOPSIS

Sandy areas in the northern China are the primary regions for potato production, but limited water resources and low water/fertilizer use efficiency limit the sustainable development of agriculture. Field experiments were conducted during 2016–2017 to investigate the effects of different drip irrigation frequencies, water amounts and fertilizer rates on the yield, quality, water and fertilizer productivity of potato in the sandy areas of northern China. The water and fertilizer treatments were evaluated using the TOPSIS method to obtain the optimal combination of irrigation frequency, water amount and fertilizer rate for multi-objective optimization. The irrigation frequency included once every 4 days (D4), once every 8 days (D8) and once every 10 days (D10). The irrigation levels consisted of full irrigation (1.0 ETc, ETc is the crop evapotranspiration), medium irrigation (0.8 ETc) and low irrigation (0.6 ETc). The fertilizer (N-P2O5-K2O) levels included low fertilization (F1, 100-40-150 kg ha−1), medium fertilization (F2, 150-60-225 kg ha−1) and high fertilization (F3, 200-80-300 kg ha−1). The results showed that there were significant effects of the irrigation frequency (IF), irrigation level (IL) and fertilization level (FL) on potato growth, yield, quality, water and fertilizer productivity. Using the same irrigation frequency and fertilization level, the highest tuber yield, starch content, vitamin C and partial factor productivity (PFP) were obtained under the full irrigation (1.0 ETc). However, the irrigation water use efficiency (IWUE) decreased as the water supply increased. In addition, these indicators under deficit irrigation increased with the increase in irrigation frequency at the same fertilization level, but the indicators of D8 were the highest under the full irrigation. Under the same irrigation frequency and irrigation level, the tuber yield and IWUE increased as the fertilization rate increased. However, the PFP decreased as the fertilizer rate increased. The trends in plant height, LAI, dry matter accumulation, plant yield and commodity tubers were similar to that in tuber yield. The starch content and vitamin C under deficit irrigation increased with the amount of fertilizer applied, but they increased first and then decreased with the increase in fertilizer rate under the full irrigation. The change in the content of reducing sugars was opposite to that of the starch. Based on the TOPSIS method, the multi-target optimum scheduling of potato was attained with the irrigation frequency of once every 8 days (D8), full irrigation(1.0 ETc and high fertilizer (N-P2O5-K2O) rate (F3, 200-80-300 kg ha−1). The obtained optimum combination of water and fertilizers can provide a scientific basis for irrigation and fertilization optimization and management in the sandy areas of northern China and in other regions with similar environments.

Evaluation of Suitable Amount of Water and Fertilizer for Mature Grapes in Drip Irrigation in Extreme Arid Regions

Low water and fertilizer use efficiency have become important factors restricting the sustainable development of agriculture in extreme arid areas, typically like Xinjiang in China. In order to optimize the water and fertilizer management system of grape drip irrigation in the region, field experiments were carried out to study the effects of different water and fertilizer treatments on the physiological growth, yield, and quality of grapes. Meanwhile, principal component analysis, grey correlation analysis, and regression analysis were used to quantify the relative optimal amount of water and fertilizer. The results showed that the effects of water and fertilizer interaction on the photosynthetic index and fluorescence index of grape leaves, in different growth periods, ng reached extremely significant levels (p < 0.01). The physiological indicators showed regular changes with the increase and decrease of water and fertilizer use and the appropriate amount of water and fertilizer could maintain the index at a superior level. Meanwhile, there are differences in the index of different growth stages and regular changes with the growth period. The effects of water and fertilizer interaction on the yield, water use efficiency, and quality of drip irrigation reached a very significant level (p < 0.01). The yield reached the maximum in W3F2 treatment and the yield increased by 29.76% compared with the minimum yield of W1F1. The quality index reached a superior level in W3F2 treatment. The results of principal component analysis and grey correlation analysis showed that the optimal water and fertilizer dosage was W3F2 (irrigation 750 mm, fertilization 750 kg ha−1), of which N (300 kg ha−1)-P2O5 (150 kg ha−1)-K2O (300 kg ha−1), and multiple regression analysis was employed to determine the optimal range of water and fertilizer use is the following: Irrigation volume 725–825 mm and fertilization amount 684–889 kg ha−1, of which N (273.6–355.6 kg ha−1) - P2O5 (136.8–177.8 kg ha−1) - K2O (273.6–355.6 kg ha−1). The research results can provide a scientific basis for the water and fertilizer management and drip irrigation technology of drip irrigation in seedless white grape fields in extremely arid areas and it is of great significance for the efficient use of regional water and fertilizer resources and the realization of sustainable socio-economic development in the region.

Salt leaching and response of Dianthus chinensis L. to saline water drip-irrigation in two coastal saline soils

Using of saline water is becoming an important approach to reclaim and utilize salt-affected soil for landscaping and agricultural purposes. A three-year field experiment was conducted in Hebei Province, North China to cultivate a perennial flower, Dianthus chinensis L., on two coastal saline soils of different textures, silt (27.79 dS·m−1) and sandy loam (27.33 dS·m−1), using the drip irrigation at five levels of water salinity (ECi = 0.8, 3.1, 4.7, 6.3 and 7.8 dS·m−1). Effect of water salinity on salt distribution in soil profile and plant growth and physiological response were investigated. The irrigation water salinity tolerance threshold of D. chinensis in terms of shoot dry weight was also evaluated. Results shown that, after three growing seasons, the highly saline soils reclaimed to < 8 dS·m−1 for silt soil and < 3 dS·m−1 for sandy loam soil under ECi < 7.8 dS·m−1. The soil salinity decreased with year and increased with increasing ECi. Better salt leaching effect occurred in sandy loam soil compared with silt soil. Plant height, clump diameter, and shoot dry weight as well as survival rate declined in response to increasing ECi, and survival rate of > 80% retained for all treatments in the third year. The decline of shoot K+ concentration, excessive accumulation of Na+, and concomitant reduction of K+/Na+ ratio were observed with increasing ECi. The irrigation water salinity thresholds of D. chinensis, aimed at biological production, are 3.17 dS·m−1 for silt soil and 1.62 dS·m−1 for sandy loam soil; for landscaping purpose, the corresponding values are 5.65 and 6.98 dS·m−1.