Physical and Chemical Properties of Soil at Southeastern Edge of Anabasis salsa in Junggar Basin北大核心CSCD

【Objective】Soil is heterogenous and its physical and chemical properties vary spatiotemporally. The purpose of this paper is to present the results of an experimental study on the physical and chemical properties of soil in Anabasis salsa in Gobi region at the southeastern edge of Junggar basin.【Method】We measured organic matter, total phosphorus, total nitrogen, electrical conductivity, pH and water content in soil at locations 5 cm and 10 cm from the center of shrubs, and 20 cm from the outer edge of shrubs.【Result】In horizonal direction, there was no significant difference in organic matter, total nitrogen, total phosphorus, electrical conductivity, pH and water content in the 0~50 cm soil at all locations. In vertical direction, the organic matter and total phosphorus in the proximity of the Anabasis salsa decreased monotonically along the soil profile, while the total nitrogen increased first with the depth followed by a decrease. Both electrical conductivity and pH increased with depth, and soil moisture peaked somewhere within the soil profile.【Conclusion】Our results showed that the physical and chemical properties of soil in Anabasis salsa did not show significant change in lateral direction but varied erratically in the vertical direction. © 2019 Authors. All rights reserved.     

Efficacy of Fertilization in Improving Soil Aggregation,Carbon and Nitrogen in Soil Reclaimed from Subsided Areas Caused by Coal Mining北大核心CSCD

【Objective】The objective of this paper is to present experimental results on efficacy of fertilization in improving aggregation and carbon and nitrogen accumulation in soil reclaimed from subsided areas caused by coal mining.【Method】The experiment was conducted under conventional irrigation with non-fertilization as the CK. We compared three treatments: applying organic fertilizer, inorganic fertilizer, and mixture of organic and inorganic fertilizer. For each treatment, we measured the size of soil aggregates, and carbon and nitrogen content in 0~20 cm and 20~40 cm soil in a coal mining-induced subsided area at Jincheng City in Shanxi Province.【Result】Compared to CK, organic fertilizer significantly increased the content of macro-aggregates sized >1 mm, and reduced the content of micro-aggregates sized < 0.25 mm. Inorganic fertilization enhanced formation of micro-aggregates, compared to organic fertilization. Applying organic fertilizer significantly increased the average weight diameter (MWD) and geometric mean diameter (GMD) of the aggregates, and reduced the fractal dimension D of the aggregates. The content of organic carbon and total nitrogen in soil under organic fertilization was the highest, followed by organic-inorganic fertilization. The content of carbon and total nitrogen in soil with a single application of inorganic fertilizer was much lower than that under organic fertilization. Majority of organic carbon and total nitrogen were found in aggregates > 0.2 mm, 1～2 mm and 0.25～1 mm, especially under organic and organic-inorganic fertilization. The C∶N ratio in all aggregates (except those in 0.053～0.25 mm) was much lower under organic and organic-inorganic fertilization than under CK, and C∶N ratio in CK and inorganic fertilization was comparable.【Conclusion】Fertilizations, especially organic fertilizer, can enhance macro-aggregation in reclaimed soil from subsided areas induced by coal mining. It also increased the content of organic carbon and total nitrogen in the aggregates. © 2019 Authors. All rights reserved.     

Experimental Study of the Suitable N-fertilizer Amount for Corn under Drip Irrigation in Aeolian Sandy Soil北大核心CSCD

【Objective】The purpose of this paper is to determine the suitable N-fertilizer amount for corn under drip Irrigation in Aeolian sandy soil. 【Method】The experiment was conducted in a field, and the amount of water and N-fertilizer were selected as experiment factors. Two levels of water amount (high and low) and three levels of N-fertilizer dosage (high, middle and low) were scheduled and thus six treatments were carried out. Effects of treatments on the growth and yield of corn were studied. 【Result】The results showed that, under low watering condition, increasing N-fertilizer amount was good for plant growth and had higher plant height and larger leaf area index, while under high watering condition, the positive effects were limited. Under both water condition, the fresh and dry weight of over ground part increased as N-fertilizer application increased, while its water contend, stem diameter and SPAD litter varied. Besides, higher N-fertilizer amount was beneficial to get longer ear, larger diameter, and more seeds, also was likely to got higher yield. The yield of high N-fertilizer amount under low and high watering condition were 13.0 and 13.7 t/hm2 respectively, 20.4% and 17.1% higher than the yield of low N-fertilizer amount treatments. 【Conclusion】In Aeolian sandy soil, higher N-fertilizer amount would be conducive plant growth and yield, especially when irrigation water was limited. Therefore, according to the experiment, N-fertilizer amount of 300 kg/hm2 was recommended in Aeolian sandy soil of northwest Liaoning. © 2019 Journal of Irrigation and Drainage. All rights reserved.     

Spatial Variability of Soil Moisture at Different Scales in Sandy Loam in Northern Henan Province北大核心CSCD

[Objective]Soil moisture plays an important role in ecosystem function and hydrological processes. This paper investigated the hieratical distribution of soil moisture at different scales over a maize field.[Method] The studied site was a 50 m×50 m plot at the Experiment Station of Chinese Academy of Agricultural Sciences in Xinxiang, Henan province. We measured soil moisture in 0~100 cm soil from 36 locations at 10 m×10 m and 2 m×2 m scale, respectively.[Result]Geostatistical analysis revealed that the soil moisture was normally distributed and its confidence level at every scale was higher than that of logarithmic normal distribution. The value of the confidence level decreased as the sampling scale increased, and the difference between average soil moisture content at fine scale and moderate scale was smaller than the difference between moderate scale and large scale. In general, the confidence interval, standard deviation and coefficient of variation of the soil moisture increased with sampling scale. At large scale, the semi-variance function increased with lag distance, while at small and moderate scale, the variation function appeared to be independent of the lag distance. To achieve the same confidence level and accuracy in estimating soil moisture, the number of samples needed to be taken from the field increased with sampling scale. We also found that in estimating soil moisture, the number of samples needed to be taken depended on the required accuracy more than on the confidence level.[Conclusion]The probabilistic distribution and statistical characteristics of soil moisture in the field was scale-dependent. In estimating soil moisture, the number of sampled taken from the field needs to consider the scales to which the measured data will be applied. © The Author(s) 2019.     

Multi-factor Analysis of the Effective Precipitation for Crops in Semi-arid Region北大核心CSCD

【Objective】The purpose of this paper is to present a method to estimate the effective precipitation for crops in arid region.【Method】The model considered precipitation, soil and crop, and it was based on four modules: canopy interception, soil water tolerance, surface runoff, precipitation and deep percolation. The results calculated by the model were compared to those calculated from water balance using the data measured from the field. We applied the model to calculate spatiotemporal distribution of the effective precipitation for crops in five counties in Hebei plain.【Result】①The coefficient of determination (R2) and Nash-Sutcliffe efficiency (NSE) in all results were above 0.85, proving the reliability of the model. ②The effective precipitation for growing season of the wheat-maize in the five counties was 400.03 mm, and the infiltration coefficient of precipitation was 0.84. In wet, normal and dry year, the effective precipitation for crops was 419, 454 and 355 mm respectively, and infiltration coefficient of precipitation was 0.76, 0.86 and 0.83 respectively. The effective precipitation for crops in Luancheng and Yuanshi was higher than that for other counties.【Conclusion】The proposed model was reliable for estimating effective precipitation for crops at large scale in semi-arid region. © 2019 Authors. All rights reserved.     

Effects of Waterlogging on Morphology and Chlorophyll Fluorescence Characteristics of Cherry Tomato at Seedling Stage北大核心CSCD

【Objective】The aim of this study was to investigate the responses of cherry tomato to waterlogging at seedling stage, and to provide reference for waterlogging resistance cultivation of off-season cherry tomato in the tropical area.【Method】Five different varieties of cherry tomatoes were used as materials in pot culture experiment, with soil waterlogging treatment and normal moisture treatment as the control (CK). The morphological characteristics indexes of shoot and root and chlorophyll fluorescence parameters in leaves of cherry tomato were measured in different days of waterlogging. And the effects of waterlogging on morphological characteristics and chlorophyll fluorescence parameters at seedling stage of cherry tomato were analyzed.【Result】Results showed that waterlogging significantly decreased the plant height, stem diameter, leaf area, leaf number and SPAD value of cherry tomato, but had no significant effect on leaf thickness. The root diameter of cherry tomato had no significant affects, but the root volume was significantly increased in HongFei 6 and TaiwanZanMei during waterlogging. Compared with CK, the root length and root surface area of HongFei 6 increased significantly, while that of QianXi decreased significantly during waterlogging. Additionally, waterlogging increased the initial fluorescence (Fo) and non-photochemical quenching coefficient (NPQ), and significantly decreased the maximum photochemical efficiency (Fv/Fm), apparent electron transfer rate (ETR) and photochemical quenching coefficient (qP) of cherry tomato leaves, besides HongFei 6.【Conclusion】The results above indicated that during waterlogging the growth and development and chlorophyll fluorescence in leaves of cherry tomato were seriously affected, but there had different effects among five different varieties . Among five varieties of cherry tomatoes, the strongest waterlogging resistance was HongFei 6, while the weakest waterlogging resistance was QianXi. © 2019 Journal of Irrigation and Drainage. All rights reserved.     

Using Biogas Slurry to Regulate Growth,Field and Fruit Quality of Greenhouse Tomato and Nitrogen Dynamics in Root Zone北大核心CSCD

【Objective】The physiological development of tomato is affected by a number of integrative abiotic and biotic factors and the purpose of this paper is to investigate how irrigation with biogas slurry alerts the yield and fruit quality of greenhouse tomato.【Method】The experiment was conducted in a greenhouse from autumn in 2017 to spring in 2018 by irrigating the tomato with a mixture of fresh water and biogas slurry at volumetric ratio of 1∶8, 1∶6 and 1∶4 at flowering stage and fruit-elongation stage respectively. In each treatment, we measured growth, yield, and fruit quality of the tomato, as well as the dynamics of total nitrogen in the root zone. 【Result】The tomato growth was positively related to the biogas slurry ratio at significant level, and the 1∶6 and 1∶4 ratio gave the highest total dry matter at the flowering stage and the fruit expansion stage respectively. The 1∶6 treatment gave the best return, and compared to CK (without biogas slurry), it increased the return by 12.93% in autumn and 12.31% in spring respectively. Irrigating with 1∶4 ratio at fruit elongation stage gave the highest yield, and compared to CK, it increased the yield by 26.59% in autumn and 27.71% in spring respectively. The 1∶4 treatment gave 4.32% increase in yield compared to chemical fertilizer application in spring. T5 and T6 treatments improved soluble sugar and solid, as well as and sugar-acid ratio, while T2 and T3 treatments increased titratable acid and vitamin C content.【Conclusion】Irrigation by mixing biogas slurry and freshwater at 1∶6 and 1∶4 volumetric ratio at flowering-fruiting stage and fruit expansion stage can considerably improve yield and quality of tomato. © 2019 Authors. All rights reserved.     

Effect of Irrigation Frequency on Water Use Efficiency and Yield of Cotton after Loosening the Deep Soil北大核心CSCD

[Objective]The objective of this paper is to experimentally investigate the responsive change in yield and water use efficiency of cotton to irrigation frequency after soil loosening.[Method]The experiment was conducted from 2016 to 2017 after deeply loosening soil. By keeping the irrigation amount the same, we compared three irrigation frequencies: Irrigating once in each 4 day (D4), 7 days (D7) and 10 days (D10) respectively. The associated irrigation times were 17, 10 and 7 respectively. In each treatment, we measured soil moisture, dry matter accumulation, water consumption, water use efficiency and the yield of the crop.[Result]After deep loosening, keeping irrigation frequency at a moderate level (D7) significantly enhanced water-holding capacity of the 0~ 20 cm soil, thereby facilitating distribution of dry matter to different organs in the bud and boll and consequently improving the water use efficiency (WUE). Compared to D4 and D10, D7 increased WUE by 15.5% and 10.5% in 2016 and 16.5% and 9.2% in 2017, respectively. Increasing irrigation frequency promoted vegetative growth and reduced distribution of the dry matter to organs in the bud and boll. In contrast, reducing irrigation frequency reduced the accumulation of total dry matter, storage of water in the top soil and water consumption. Compared to D4 and D10, D7 increased the yield by 13.8% and 7.0% in 2016, and 17.3% and 6.1% in 2017. The main mechanism underlying in yield increase in D7 was the increase in boll number and average weight of the bolls in each plant. [Conclusion]Irrigating once after each 7 days, together with deep soil loosening, can effectively promote vegetative growth and organ production from dry matter, thereby facilitating the conversion of dry matter to organs and improving cotton yield and its water use efficiency. © 2019 TEST-ZL Publishing, LLC. All rights reserved.     

Study on the Variation Characteristics of Rising Capillary Water of Layered Soil under Variation of Sand Layer and Thickness北大核心CSCD

【Objective】The purpose of this paper is to solve secondary salinization of soil in Northwest China. 【Method】the capillary water rising movement characteristics of layered soil has been analyzed through indoor test. And the variation characteristics of capillary water movement under the influence of common change of layer and thickness of sand layer has been considered in this paper, and functional relationship between groundwater recharge and height of capillary water rising with time changing has been built. Furthermore, contour distribution of groundwater recharge and capillary water rising height has been also comparative analyzed.【Result】There was a very significant positive correlation between the horizon and the volume constant and the height constant （P<0.01）. And there was a significant negative correlation between the horizon and the stable recharge rate of groundwater and the rate of steady increase of capillary water （P<0.05）. There was a significant negative correlation between the thickness of sand layer and stable recharge rate and steady rising rate（P<0.05）. When the duration of the capillary water height was rising was 0~4 days, the sandy layer was 30~50 cm, the thickness of sand layer was 0~15 cm, which has a significant effect on the change of groundwater recharge and height of capillary water. When the duration of the capillary water height was rising was 4~12 days, the sand layer is distributed in 15~30 cm, the thickness of sand layer was 15~30 cm, which has a significant effect on the change of groundwater recharge and height of capillary water. To summarize, the results of this study were of great significance for the study of water salt movement and soil salinization in layered soils.【Conclusion】The fitting parameters of the function including volume constant (v), stable recharge rate (q*), groundwater recharge time constant (τQ), capillary water rising height (υ), steady rising rate (μ*) and rising height time constant (τh) were determined by the variation of capillary groundwater recharge and capillary water height with time changing respectively. © 2019 Journal of Irrigation and Drainage. All rights reserved.     

Retrieving Soil Moisture Using Spectral Mixture Analysis of Landsat8 and the Moderate Resolution Imaging Spectroradiometer北大核心CSCD

【Objective】Soil moisture plays a critical role in many hydrological and ecological processes and understanding its spatiotemporal changes is imperative to ecosystem management and irrigation design. This paper presents and tests a method to estimate soil moisture distribution using satellite technologies.【Method】We took Guangli Irrigation District at Jiaozuo in Henan Province as our study area. The Landsat-8 and MODIS imageries from the area were used to retrieve soil moisture with the apparent thermal inertia and vegetation water supply index, respectively. Using the abundance of vegetation and soil moisture decomposed by the spectral mixture analysis as weighting factors, we retrieved the soil moisture distribution in the area using the two methods.【Result】The correlation coefficient between the measured soil moisture and the retrieved using the vegetation water supply index method and the apparent thermal inertia method was 0.47 and 0.51 respectively. We found that combining the two methods could improve the correlation coefficient between the measured and retrieved soil moisture to 0.73. 【Conclusion】Our results showed that the proposed method is reliable and can adequately estimate soil moisture in irrigation district grown with a diverse of crops. © 2019 Authors. All rights reserved.     

Evaluation and Driving Force of Water Resources Carrying Capacity in Dianchi Basin北大核心CSCD

【Objective】The purpose of this paper to explore the coordination relationship between the water resources carrying capacity of the Dianchi Lake Basin and the socio-economic development and environment of the basin. 【Method】Select the water resources, social economy and environment-related indicators to construct a comprehensive evaluation model for the water resources carrying capacity of the Dianchi Lake Basin. The trend of pressure index, bearing capacity index, coordination index and water resources carrying capacity index of the basin from 2011 to 2015 was calculated and analyzed. The factor analysis method was used to further evaluate the water resources carrying capacity of the basin, and the main factors extracted were used. The driving force model of water resources carrying capacity was constructed to identify the main driving forces that affect the water resources carrying capacity of the Dianchi Lake Basin. 【Result】The water resources carrying capacity index of Dianchi Lake Basin showed an upward trend from 2011 to 2015; The main driving forces of water resources carrying capacity in Dianchi Basin were human activity factors and natural factors, including urbanization rate, economic development factors and annual average temperature and annual. Precipitation. GDP per capita and annual precipitation wrer positive drivers, and urbanization rates and annual average temperatures are negative drivers. 【Conclusion】Based on the sustainable development of social economy and the coordinated development of water resources system, the construction of water transfer project from the outer basin to Dianchi Lake Basin should be increased to form a multi-water source combined water transfer pattern, and the population quantity should be controlled on the basis of ensuring vigorous economic development. Establish a sound water resource efficient allocation and unified scheduling scheme for multi-source water supply in the basin water resources system. © 2019 Office of Journal of Irrigation and Drainage, Farmland Irrigation Research Institute, Chinese Academy of Agricultural Sciences. All rights reserved.     

Response in Growth,Quality and Water Consumption of Greenhouse Tomato to Change in Matric Potential at 20 cm below the Emitter of Drip Irrigation北大核心CSCD

[Objective]Irrigation schedule needs to know the spatiotemporal dynamics of soil moisture in root zone. The objective of this paper is to investigate the feasibility of using matric potential measured at 20 cm below the drip emitter as a proxy for soil moisture in the root zone to schedule irrigation.[Method]The experiment was conducted in a greenhouse and the model plant was tomato. We compared seven matric potential (SMP) thresholds in that whenever the measured soil matric potential dropped below them, drip irrigation was resumed. The values of the SMP thresholds varied from flowering and fruit-setting stage to fruiting stage, and the seven combinations (flowering and fruit-setting stage/fruiting stage) were -15 kPa/-15 kPa (S1), -15 kPa/-30 kPa (S2), -15 kPa/-45 kPa (S3), -25 kPa/-25 kPa (S4), -30 kPa/-15 kPa (S5), -30 kPa/-30 kPa (S6), and -30 kPa/-45 kPa (S7). In each treatment, we measured growth, fruit quality, water consumption and water use efficiency of the tomato.[Result]Stem diameter increased with SMP threshold at both flowering and fruit-setting stage and fruiting stage, whereas the plant height was only responsive to SMP at flowing and fruit-setting stage. The relative chlorophyll content in leaf (SPAD) did not show significant difference between treatments at flowering and fruit-setting stage but inversely increased with the SMP threshold at fruit setting stage. Decreasing the SMP threshold at flowering and fruit-setting stage could reduce the percentage of defective fruits and increase soluble solids content. Yield increased inversely with SMP threshold at fruit setting stage, peaking when SMP was -45 kPa. Lowering the SMP threshold increased irrigation amount and hence water consumption, thereby decreasing water use efficiency. [Conclusion]Our experimental results suggest that setting the SMP at -30 kPa at the flowering and fruit-setting stage and -45 kPa at the fruiting period appears to be optimal to best balance yield, fruit quality, irrigation water use efficiency and water use efficiency for winter-spring tomato grown in solar greenhouse in North China. © The Author(s) 2019.     

The Use of Brackish and Reclaimed Waste Water in Agriculture: A Review北大核心CSCD

Due to poor water resources management and appropriate water treatment technologies, freshwater resources depletion and water quality deterioration has made reclaimed waste water, brackish water and rainwater, called unconventional water, an important complementary resource for irrigation. However, due to its unique chemical quality, irrigating with unconventional water might lead to some detrimental impact on environment and impose health risks, which has attracted increased attention in both scientific and public community. This paper reviews the current situation of the usage of unconventional water resources for irrigation in both China and beyond, and summarized the potentially ecological risks of unconventional water, as well the national standards for regulating unconventional water irrigation. We also put forwards suggestions to improve safe and sustainable use of unconventional water resources for irrigation. © 2019 Authors. All rights reserved.     

Sensitivity Analysis of the Reference Evapotranspiration in Ebinur Lake Oasis北大核心CSCD

【Objective】The evapotranspiration of crop depends on many factors and this paper analyzed its sensitivity to various meteorological factors in Ebinur lake oasis.【Method】Monthly ET0 in Ebinur lake oasis was calculated using the Penman-Monteith formula based on meteorological data measured from 1962 to 2016 at four meteorological stations in the region. The sensitivity of ET0 to the highest and lowest temperature, relative humidity, sunshine duration and wind speed was calculated using sensitivity analysis; and the possible existence of any trends in the ET0 was analyzed using the MK trend test. We also calculated the variation of the sensitivity coefficient for each site.【Result】The MK trend test revealed that the evapotranspiration, sunshine duration and wind speed in the region have been in decline, while the highest and lowest temperature and the relative humidity have been in rise. Analysis found that the ET0 was sensitive to meteorological factor in an order of relative humidity > the highest temperature > wind speed > the lowest temperature > sunshine duration. The sensitivity coefficient of ET0 to different meteorological factors varies spatially, with the coefficients for the highest and lowest temperature, wind speed and relative humidity being high at Alashan pass-way in northern Ebinur lake, and low at Wenquan station. Wenquan station had longer sunshine duration than Alashan pass-way.【Conclusion】ET0 is most sensitive to relative humidity in Ebinur lake oasis, and least sensitive to sunshine duration. © 2019 Authors. All rights reserved.     

Calculation of Irrigation Infiltration Recharge Coefficient and Analysis of Influencing Factors in the Lower Reaches of Aksu River北大核心CSCD

【Objective】In order to obtain the irrigation infiltration recharge coefficient in the lower reaches of Aksu river and improve the numerical simulation accuracy of groundwater in the study area,the influencing factors of the irrigation infiltration recharge coefficient in this area were analyzed. 【Method】In this paper,field sampling and indoor irrigation experiments were carried out by selecting representative points under different irrigation schemes,vadose zone thickness and soil structure in the lower Aksu area,and numerical simulation of vadose zone flow was carried out in combination with Hydrus-1d. Hydrus-1d model was used to calculate irrigation inflow under this soil structure by changing irrigation schemes and vadose zone thickness. Change of seepage recharge coefficient. On the basis of the calculation results of the model,the relationship between irrigation schedule,aeration zone thickness and irrigation infiltration recharge coefficient is analyzed firstly,and then the main factors affecting irrigation infiltration recharge coefficient in soil structure are analyzed with the method of model calculation and mathematical statistics. 【Result】The results showed that the irrigation infiltration recharge coefficient ranged from 0.320 to 0.474 under drip irrigation and from 0.408 to 0.561 under border irrigation. The irrigation infiltration recharge coefficient varied under different irrigation schemes,while the irrigation infiltration recharge coefficient decreased with the increase of aeration zone thickness. The main factors affecting irrigation infiltration recharge are soil permeability coefficient,soil bulk density and initial soil water content. 【Conclusion】According to indoor experiment combined with numerical model to calculate the irrigation infiltration coefficient under different irrigation system range, it is concluded that the influence factors of irrigation infiltration coefficient of irrigation system, the thickness of the vadose zone and reflects soil permeability coefficient of soil structure, soil quality and soil initial moisture content, volume for the downstream area irrigation infiltration coefficient selection in arid areas and provides the theory basis for further research. © 2019 Journal of Irrigation and Drainage. All rights reserved.     

Analysis of Drought Characteristics and Short-term Prediction in Ji’an Area during 1960―2018北大核心CSCD

【Objective】The purpose of this paper is to further explore the drought condition of Ji’an area in terms of spatial and temporal distribution characteristics, evolution tendency and future situation of drought. 【Method】The result of this paper was concluded based on the different time scale SPI values of precipitation during 1960―2018 among the 13 districts and counties of Ji’an city. The inverse distance weight method was adopted to interpolate the drought frequency. And the spatial distribution characteristics of annual and seasonal drought were analyzed in the research. Moreover, the trends, occurrence timing characteristics, impact range and severity of drought were analyzed by Linear regression method, Mann-Kendall trend test, drought station sub-ratio and run of theory; Precipitation status was also predicted by weighted Markov Model. 【Result】The frequency and range of drought in Ji’an area decreased on the annual scale in terms of the light drought and extreme drought conditions. Droughts in Autumn and winter were more severe because the occurrence frequency was about 30%. However, drought in summer varied greatly on regional distribution. Overall, the spring drought had a tendency to increase in many places; while the summer drought was weakening. The whole basin drought events tended to occur intensively in a short period of time, and the drought area has been reduced obviously in a 20-year cycle, the severity of drought also have been reduced. In conclusion, it was predicted that 6 to 8 regions will be in the low level water condition in 2019 and 2020. 【Conclusion】Ji’an area should focus on drought prevention work in the autumn and winter seasons, and pay attention to the large-scale drought events that may occur in the early 2020s. © 2019 Office of Journal of Irrigation and Drainage, Farmland Irrigation Research Institute, Chinese Academy of Agricultural Sciences. All rights reserved.     

Effects of canopy size and water stress over the crop coefficient of a “Tempranillo” vineyard in south-western Spain

This paper describes the assessment of the crop coefficient of an irrigated Tempranillo vineyard measured in a weighing lysimeter during 5?years in south-western Spain. During the first year of the study (2006), young vines displayed a different canopy growth compared to the subsequent years. From 2007 to 2010, vines experienced 2?years with no restriction in water supply, and two other years with short periods of crop water stress. Basal crop coefficient (K _cb) started from 0.2 at bud-break until 1.0 at full development in every year, being this maximum management-dependent. K _cb showed a good correlation with canopy size indices, which allows to interpolate these results to a wide range of commercial vine systems that are usually managed with lower vegetation size. Moreover, a simple linear model of crop evapotranspiration reduction with relative water content is presented, allowing the estimation of consumptive water use under deficit irrigation conditions.     

Simulations on direct and cyclic use of saline waters for sustaining cotton–wheat in a semi-arid area of north-west India

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 ET_rel (≥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 ET_rel.