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In order to alleviate the shortage of water in Xinjiang cotton fields, to ensure the sustainable development of the cotton industry in southern Xinjiang, it is necessary to determine a suitable "dry sowing and wet emergence" water quantity plan for cotton fields in southern Xinjiang to change the current situation. In this study, to explore the irrigation regime of "dry sowing and wet emergence" for cotton in Korla, Xinjiang, by combining field experiments and modeling simulations, the effects of different irrigation amounts on the water–heat–salt and seedling emergence characteristics of "dry sowing and wet emergence" cotton fields were investigated; the soil, water, and salt transport under different irrigation regimes was simulated by using HYDRUS-2D, and the seedling emergence rate of the cotton under different irrigation regimes was obtained through the establishment of a regression model. The results indicated that, in the field experiment, the soil water content of the 0−40 cm soil layer showed an overall trend of first increasing and then decreasing with time, while the soil salt content showed an overall trend of first decreasing and then increasing over time. The soil water content at the drip heads and cotton rows position, as well as on the 15th day, increased by an average of 5.58 cm3·cm−3 compared to before irrigation, and the soil salt content decreased by an average of 2.74 g/kg compared to before irrigation. In the irrigation water range of 675−825 m3/hm2, reducing the irrigation water amount increased the cotton emergence rate by 3.86% and the cotton vigor index by 70.53%. After the model simulation, it is recommended to choose the cotton "dry sowing and wet emergence" irrigation regime with a low to medium water amount (300−450 m3/hm2) at 14-day intervals or a low to medium water amount (300−375 m3/hm2) at 7-day intervals, which can obtain a higher seedling emergence rate. [ABSTRACT FROM AUTHOR]

In order to alleviate the shortage of water in Xinjiang cotton fields, to ensure the sustainable development of the cotton industry in southern Xinjiang, it is necessary to determine a suitable “dry sowing and wet emergence” water quantity plan for cotton fields in southern Xinjiang to change the current situation. In this study, to explore the irrigation regime of “dry sowing and wet emergence” for cotton in Korla, Xinjiang, by combining field experiments and modeling simulations, the effects of different irrigation amounts on the water–heat–salt and seedling emergence characteristics of “dry sowing and wet emergence” cotton fields were investigated; the soil, water, and salt transport under different irrigation regimes was simulated by using HYDRUS-2D, and the seedling emergence rate of the cotton under different irrigation regimes was obtained through the establishment of a regression model. The results indicated that, in the field experiment, the soil water content of the 0−40 cm soil layer showed an overall trend of first increasing and then decreasing with time, while the soil salt content showed an overall trend of first decreasing and then increasing over time. The soil water content at the drip heads and cotton rows position, as well as on the 15th day, increased by an average of 5.58 cm3·cm−3 compared to before irrigation, and the soil salt content decreased by an average of 2.74 g/kg compared to before irrigation. In the irrigation water range of 675−825 m3/hm2, reducing the irrigation water amount increased the cotton emergence rate by 3.86% and the cotton vigor index by 70.53%. After the model simulation, it is recommended to choose the cotton “dry sowing and wet emergence” irrigation regime with a low to medium water amount (300−450 m3/hm2) at 14-day intervals or a low to medium water amount (300−375 m3/hm2) at 7-day intervals, which can obtain a higher seedling emergence rate.

A meta-analysis was conducted with the aim of exploring the influence of irrigation on potato yield, evapotranspiration (ET), and water-use efficiency (WUE) in northern China, considering factors such as irrigation methods, growing region, irrigation water-use efficiency (IWUE), irrigation frequency, soil types, and nitrogen (N) fertilizer rate. Overall, irrigation significantly increased potato yield and ET by an average of 45 and 54% compared to non-irrigation, respectively, but did not significantly increase the WUE. The increase in potato yield under irrigation is the most evident in aeolian sandy soil in northeast China and northwest China. Drip irrigation demonstrated the highest positive impact on both yield and WUE. Optimal yields were achieved with an irrigation amount ranging from 100 to 200 mm, while the highest WUE was observed with an irrigation amount of 30–50 mm. When the amount of irrigation exceeded 100 mm, the irrigation significantly resulted in decreased WUE compared to non-irrigation. The relative increase in yield per unit of irrigation amount and IWUE gradually decreased and eventually stabilized when the irrigation amount exceeded 100 mm. Therefore, the yield and WUE perform best when the irrigation amount is below 100 mm and the irrigation frequency is less than three times for sprinkling and flood irrigation methods. The greatest increases in yield and WUE under irrigation were found under a moderate N rate (150–250 kg N ha−1). Additionally, the relative increase in yield per unit of irrigation amount decreases gradually as the organic matter content increases. These findings suggest that the optimal benefits from irrigation might be realized when the irrigation amount is below 100 mm, with a moderate nitrogen fertilizer application and an irrigation frequency of three times. However, it is essential to consider local environmental factors such as the growing region, soil types, and organic carbon content. [ABSTRACT FROM AUTHOR]

Optimizing irrigation strategies is crucial for sustaining cotton production in the face of growing water scarcity. The three-year experimental study (2020–2022) focused on the impact of varying irrigation amounts (320, 370, and 420 mm) and frequencies (4-, 8-, and 12-day intervals) on cotton growth, yield, yield components, and fiber quality in southern Xinjiang. Employing a completely randomized design with three replications, the results indicated higher irrigation amounts resulted in numerically 2.5–7.5% higher lint yields compared to those under medium and low irrigation amounts, notably significant in 2021. Boll density emerged as the primary yield component influencing yield loss due to irrigation amount, followed by seed cotton weight boll−1. Increased boll density was associated with a greater total number of fruiting sites. Additionally, the increased seed cotton weight boll−1 could be linked to an increased seed number boll−1 and a decreased boll fraction at the lower fruiting branches with lower seed cotton weight boll−1. Higher irrigation frequency improved lint yield by increasing boll density, though a significant effect was observed only in 2020. Increased irrigation amounts generally led to longer fiber lengths but lower micronaire values, while increased irrigation frequency resulted in longer, stronger fibers and reduced micronaire values. Furthermore, the highest yield stability was observed under the condition of high irrigation amount and high frequency. This study holds certain guiding significance for water resource management in cotton production in arid regions. [ABSTRACT FROM AUTHOR]

Biodegradable film (BF), as a superior substitute for traditional polyethylene film (PF), has experienced a consistent increase in China. However, a significant research gap persists regarding the utilization of BF in assessing farmland carbon balance. This experiment examined the responses of maize growth, yield, irrigation water productivity (IWP), CO2 emissions, and field net carbon sequestration (NCS) to two BF types (BF1, 100-day induction period, and BF2, 80-day induction period), and PF, and three irrigation amounts (I1, I2, I3: 5250, 5625, and 6000 m3 ha–1), by conducting a two-year (2019–2020) field trial in a typical arid and semi-arid region of China. The results indicated that biodegradable film mulching (BFM) negatively affected maize growth, resulting in reduced yield and IWP. Especially under the I1 irrigation level, the biodegradable film reduced maize yield by 6.26%–13.99% and IWP by 6.64–13.85%. Notably, in the I2 irrigation level, BF1 mulching had a comparable impact on maize yield and IWP to that of PF. Additionally, the increase in irrigation amounts exerted a more pronounced promoting effect on maize total biomass than on yield and IWP. Concerning carbon balance, short-term BF application resulted in reduced CO2 emissions (5.74–6.30% under BF1 and 9.27–12.37% under BF2), without any significant impact on NCS in cropland. Taking into account the economic value of maize and farmland ecology, we recommended utilizing irrigation amounts of 5625 m3 ha–1 for BF application in arid areas, while opting for a BF with a longer induction period whenever feasible.

In the soil column experiments, the irrigation amount varied from 4.8 to 12 L, and the nitrogen application rate was from 80 to 360 kg ha−1. Three fertigation strategies were tested. The results indicated that an increase in water input led to an increase in the area of pH decrease in the soil at 10 days after the irrigation ended for a given lateral depth of 10 cm. The measurement of nitrogen distribution showed that the nitrogen content in the soil was significantly increased with the nitrogen application rate. Fertigation strategies substantially affect the pH and nitrogen distributions in soil. The strategy of applying water at first for one-fourth of the total irrigation time (1/4W), then applying fertilizer solution for one-half of the total irrigation time (1/2N), followed by applying water for the remaining one-fourth of the total irrigation time (1/4W) made a minimal soil pH decreasing area and a homogeneous nitrate distribution at 0–20 cm depth. Therefore, to reduce NO3-N leaching and avoid deep soil acidification, a dripline depth of 10 cm with an irrigation amount of 4.8 L and a nitrogen application rate of 80 kg ha−1 through the 1/4W–1/2N–1/4W fertigation may be suggested. HIGHLIGHTS Minor water and nitrogen input with shallow lateral depth can be conducive to reduce nitrate leaching.; The NO3-N accumulation and pH decrease mainly appeared in surface soil through 1/4W–1/2N–1/4W fertigation.; Drip irrigation is feasible to mitigate soil acidification.; An ongoing field experiment confirms and improves the results of laboratory experiments without crops.;

Winter irrigation is widely carried out to alleviate soil salinization in Northwest China. In recent years, the effects of irrigation amount and irrigation schedule on soil water and salt distribution and water use efficiency (WUE) during crop growth periods have been extensively studied, but the effects of winter irrigation on water use efficiency have been generally ignored. This work was conducted from November 2018 to October 2020 in two kinds of saline-alkali farmlands (mild saline-alkali farmland and moderate saline-alkali farmland) with five winter irrigation amounts (0, 150, 225, 300 and 375 mm). The results indicated that, during the winter irrigation period, the maximum moisture content layer in the soil becomes more shallow with the increase in the winter irrigation amount and the salinity of the soil. The salt return process mainly occurs during the late thawing period. After two years, for a winter irrigation amount of 150 mm to 375 mm, the change rate of soil salt in mild saline-alkali farmland decreased from −2.50% to −15.38% in the 0–100 cm profile, and that value in moderate saline-alkali farmland decreased from 12.22% to −16.85%. Compared with the non-winter irrigation treatment, the sprouting rate, survival rate, morphological index and cotton yield in the coming year are greater under the winter irrigation treatment. For mild saline-alkali farmland and moderate saline-alkali farmland, to keep soil desalinated, enhance cotton growth and save water resources, the recommended winter irrigation amounts are 225 mm and 300 mm, respectively. The research methods and results are of great significance for rationally evaluating the sustainable winter irrigation amount for cotton fields under mulched drip irrigation in different saline-alkali farmlands. [ABSTRACT FROM AUTHOR]

Soil organic carbon is very important to increase crop yield. Understanding the composition changes and migration characteristics of SOC under different irrigation conditions in arid oasis areas is of great significance for the sustainable development of agro-ecosystem and the estimation of carbon balance of farmland ecosystem in arid areas. In this paper, classical statistics and geostatistics were used to study the leaching characteristics and migration laws of soil organic carbon under different irrigation conditions in Minqin Oasis, and the leaching amount and loss process and mechanism of SOC under different irrigation conditions were quantified. The research results showed that: (1) Irrigation increased the average 0–100 cm SOC content. After irrigation, SOC content decreased first and then increased with the increase in soil depth, with the maximum value of 8.56 g/kg and the minimum value of 1.82 g/kg. Compared with that before irrigation, SOC content in 0–30 cm surface layer was in leaching state, SOC content in 30–70 cm surface layer was accumulated, and SOC content in 70–100 cm surface layer had no obvious change. (2) Water was an important factor affecting soil carbon. The greater the irrigation amount, the higher the carbon leaching rate and the greater the migration amount. The SOC content in 0–30 cm soil layer was most significantly affected by irrigation, and the migration amount of SOC gradually decreased with the increase in soil depth. The maximum leaching rate of SOC was 36.8%, the minimum leaching rate was 13.5%, and its average leaching rate was 23.4%. (3) Due to the influence of soil infiltration rate under water, SOC content in different irrigation periods showed that the greatest SOC occurred in the 0–70 cm layer, and SOC content in soil was basically the same as that in non-irrigated areas on the fifth day after irrigation. (4) Precipitation, plastic film mulching, soil physical and chemical properties and other environmental factors were important factors affecting the migration and change in SOC content. [ABSTRACT FROM AUTHOR]

A two-year field experiment was conducted to evaluate the effect of irrigation and nitrogen amount on maize growth and water productivity for saline soil. The main treatments were four nitrogen levels 0 (N0), 215 (N1), 270 (N2), and 325 kg ha−1 (N3) and three irrigation levels 500 (W1), 400 (W2), and 300 mm (W3). The results demonstrated that all treatments were in salt leaching state in 2016 and in salt accumulation state in 2017. Soil salinity decreased with increasing nitrogen amount while nitrogen amount was lower than 270 kg ha−1 under W2, but increased with increasing nitrogen amount under W3. Compared with W1N2, the reduction in plant height and leaf area index of W2N2 was less than 7.0%. The total water consumption decreased with decreasing irrigation and nitrogen amount. Yield of W2N2 was only 5.0% less than W1N2 in 2016, but obtained the largest yield in 2017. Yield and water use efficiency were elevated while nitrogen amount increased from 0 to 270 kg ha−1, but were decreased while nitrogen amount exceeded 270 kg ha−1. Thus, irrigation amount 400 mm in combined with nitrogen amount 270 kg ha−1 could alleviate salt accumulation, promote maize growth, and ensure maize yield. [ABSTRACT FROM AUTHOR]

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A meta-analysis was conducted with the aim of exploring the influence of irrigation on potato yield, evapotranspiration (ET), and water-use efficiency (WUE) in northern China, considering factors such as irrigation methods, growing region, irrigation water-use efficiency (IWUE), irrigation frequency, soil types, and nitrogen (N) fertilizer rate. Overall, irrigation significantly increased potato yield and ET by an average of 45 and 54% compared to non-irrigation, respectively, but did not significantly increase the WUE. The increase in potato yield under irrigation is the most evident in aeolian sandy soil in northeast China and northwest China. Drip irrigation demonstrated the highest positive impact on both yield and WUE. Optimal yields were achieved with an irrigation amount ranging from 100 to 200 mm, while the highest WUE was observed with an irrigation amount of 30–50 mm. When the amount of irrigation exceeded 100 mm, the irrigation significantly resulted in decreased WUE compared to non-irrigation. The relative increase in yield per unit of irrigation amount and IWUE gradually decreased and eventually stabilized when the irrigation amount exceeded 100 mm. Therefore, the yield and WUE perform best when the irrigation amount is below 100 mm and the irrigation frequency is less than three times for sprinkling and flood irrigation methods. The greatest increases in yield and WUE under irrigation were found under a moderate N rate (150–250 kg N ha−1). Additionally, the relative increase in yield per unit of irrigation amount decreases gradually as the organic matter content increases. These findings suggest that the optimal benefits from irrigation might be realized when the irrigation amount is below 100 mm, with a moderate nitrogen fertilizer application and an irrigation frequency of three times. However, it is essential to consider local environmental factors such as the growing region, soil types, and organic carbon content.

Optimizing irrigation strategies is crucial for sustaining cotton production in the face of growing water scarcity. The three-year experimental study (2020–2022) focused on the impact of varying irrigation amounts (320, 370, and 420 mm) and frequencies (4-, 8-, and 12-day intervals) on cotton growth, yield, yield components, and fiber quality in southern Xinjiang. Employing a completely randomized design with three replications, the results indicated higher irrigation amounts resulted in numerically 2.5–7.5% higher lint yields compared to those under medium and low irrigation amounts, notably significant in 2021. Boll density emerged as the primary yield component influencing yield loss due to irrigation amount, followed by seed cotton weight boll−1. Increased boll density was associated with a greater total number of fruiting sites. Additionally, the increased seed cotton weight boll−1 could be linked to an increased seed number boll−1 and a decreased boll fraction at the lower fruiting branches with lower seed cotton weight boll−1. Higher irrigation frequency improved lint yield by increasing boll density, though a significant effect was observed only in 2020. Increased irrigation amounts generally led to longer fiber lengths but lower micronaire values, while increased irrigation frequency resulted in longer, stronger fibers and reduced micronaire values. Furthermore, the highest yield stability was observed under the condition of high irrigation amount and high frequency. This study holds certain guiding significance for water resource management in cotton production in arid regions.

The Yellow River Water Allocation Management Method was put into place in 1998 to decrease the Yellow River water amount used by upstream areas and provide more water to downstream regions. Rainfall and Yellow River's infiltration are the main groundwater supply in the downstream area of Yellow River. The groundwater table in the downstream area has continued to decrease since 1979, and the extracted groundwater for irrigation is the main reason for this. Whether the increased river water amount could improve the decreased groundwater level is uncertain. Therefore, we used remote sensing images, groundwater level observations, meteorological data, and unit mean irrigation rate to identify the irrigation events for river water and groundwater, estimate the annual river water irrigation amount and groundwater irrigation amount, and analyze the effects of river water allocation on the groundwater table. Our analysis showed that the area of double-irrigated farmland (farmland that could be irrigated by both groundwater and river water) tended to decrease, while well-irrigated farmland area (farmland that could only be irrigated by groundwater) remained unchanged during the study period. The number of annual irrigation events tended to increase, and the usage of river water remained consistent throughout this period. The increased number of well irrigation events caused annual groundwater usage for irrigation to increase. However, the usage of river water for irrigation remained stable. The increased usage of groundwater for irrigation led the groundwater table to continually decrease from 1998 to 2019. This indicates that there are shortcomings to the current water allocation policy, and that further improvements are needed to prevent continued decrease in groundwater levels. [ABSTRACT FROM AUTHOR]

Water and nitrogen are vital factors limiting dry matter accumulation (DMA) and yield formation of spring maize. Simulation of DMA in spring maize under different irrigation and nitrogen application levels is conducive to better field management. Logistic model is a simple and effective measure to simulate the DMA. However, the coupling effect of water amount and nitrogen rate on logistic model parameters for spring maize in Northwest China has received little attention thus far. In this study, regression equations between logistic model parameters, water amount (i.e. irrigation plus rainfall), and nitrogen application rate were established and validated using independent data sets from three experiment sites (Wuwei in Gansu Province, Guyuan in Ningxia Province and Bayannur in Inner Mongolia Autonomous Region). Similarly, the empirical model of harvest index was established and validated. The results showed that these regression equations can accurately predict the dry matter accumulation and yield of spring maize. Therefore, this study can provide an alternative simple method to predict DMA and yield of spring maize under various water and nitrogen treatment in this area. [ABSTRACT FROM AUTHOR]

Abstract Background Cotton production in China is challenged by high labor input including manual topping (MT). Recently, to replace MT in the Xinjiang cotton region of China, mepiquat chloride (MC) was applied once more than the traditional multiple-application; this was designated as chemical topping (CT), but it is unclear whether the amount of irrigation needs to be adjusted to accommodate CT. Results The main plots were assigned to three drip irrigation amounts [300 (I1), 480 (I2), and 660 (I3) mm], and the subplots were assigned to the CT treatments [450 (MC1), 750 (MC2), and 1 050 (MC3) mL·hm−2 25% MC] with MT as a control that was performed after early bloom. The optimum drip irrigation amount for CT was explored based on leaf photosynthesis, chlorophyll fluorescence, biomass accumulation, and yield. There were significant influences of drip irrigation, topping treatments and their interaction on chlorophyll fluorescence characteristics, gas exchange parameters and biomass accumulation characteristics as well as yield. The combination of I2 and MC2 (I2MC2) performed best. Compared with I2MT, the net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), and photochemical quenching coefficient (qP) of I2MC2 significantly increased by 4.0%∼7.2%, 6.8%∼17.1%, 5.2%∼17.6%, and 4.8%∼9.6%, respectively, from the peak flowering to boll opening stages. Moreover, I2MC2 showed fast reproductive organ biomass accumulation and the highest seed cotton yield; the latter was 6.6%∼12.8% higher than that of I2MT. Further analysis revealed that a 25% MC emulsion in water (MCEW) application resulted in yield improvement by increasing Pn, φPSII, and qP to promote biomass accumulation and transport to reproductive organs. Conclusion The results showed that the 480 mm drip irrigation combined with 750 mL·hm−2 MC increased the rate of dry matter accumulation in reproductive organs by increasing Pn, φPSII, and qP to improve photosynthetic performance, thus achieving higher yield.

Soil organic carbon is very important to increase crop yield. Understanding the composition changes and migration characteristics of SOC under different irrigation conditions in arid oasis areas is of great significance for the sustainable development of agro-ecosystem and the estimation of carbon balance of farmland ecosystem in arid areas. In this paper, classical statistics and geostatistics were used to study the leaching characteristics and migration laws of soil organic carbon under different irrigation conditions in Minqin Oasis, and the leaching amount and loss process and mechanism of SOC under different irrigation conditions were quantified. The research results showed that: (1) Irrigation increased the average 0–100 cm SOC content. After irrigation, SOC content decreased first and then increased with the increase in soil depth, with the maximum value of 8.56 g/kg and the minimum value of 1.82 g/kg. Compared with that before irrigation, SOC content in 0–30 cm surface layer was in leaching state, SOC content in 30–70 cm surface layer was accumulated, and SOC content in 70–100 cm surface layer had no obvious change. (2) Water was an important factor affecting soil carbon. The greater the irrigation amount, the higher the carbon leaching rate and the greater the migration amount. The SOC content in 0–30 cm soil layer was most significantly affected by irrigation, and the migration amount of SOC gradually decreased with the increase in soil depth. The maximum leaching rate of SOC was 36.8%, the minimum leaching rate was 13.5%, and its average leaching rate was 23.4%. (3) Due to the influence of soil infiltration rate under water, SOC content in different irrigation periods showed that the greatest SOC occurred in the 0–70 cm layer, and SOC content in soil was basically the same as that in non-irrigated areas on the fifth day after irrigation. (4) Precipitation, plastic film mulching, soil physical and chemical properties and other environmental factors were important factors affecting the migration and change in SOC content.

Water scarcity is a worldwide problem, and in order to obtain plenty of production, agricultural irrigation water accounts for a large portion. Many studies have shown that the interaction of root microorganisms and soil can promote crop growth. Developing ways to reduce irrigation to maintain soil fertility and ensure crop yield by regulating the root microenvironment is an important research goal. Here, we developed a reasonable irrigation plan for eggplant cultivation in a solar greenhouse. The maximum theoretical amount of water demand during eggplant planting obtained from a previous study was used as the control (CK), and the irrigation in the treatments was reduced by 10, 20 and 30% relative to this amount. The 10% irrigation reduction treatment (T1) significantly improved soil nutrients and increased soil catalase, urease and alkaline phosphatase activities (p < 0.05). Further analysis of rhizosphere microorganisms revealed the highest richness and diversity of the microbial community under the T1 treatment, with Bacilli as the most abundant bacteria and Aspergillaceae as the most abundant fungi and lower relative abundances of Chloroflexi and Acidobacteria (p < 0.05). Changes in microbial community structure under the influence of different irrigation treatments resulted in improvements in rhizosphere N cycling and nutrient catabolism. The plant– microbe interactions led to significant increases in eggplant plant height, root vigour, root surface area, leaf chlorophyll a, leaf net photosynthetic rate, water use efficiency, transpiration rate, and stomatal conductance under the T1 treatment compared to the CK treatment; soluble sugar, soluble protein and free amino acid contents in eggplant fruit increased by 10.8, 12.3 and 6.7%, respectively; and yield increased by 3.9%. Our research proved that the 10% irrigation reduction treatment (T1) could improve microbial community richness and fruit yield, which would improve irrigation efficiency and cost reduction in agriculture. [ABSTRACT FROM AUTHOR]

The mechanism of greenhouse tomato growth and yield under the integrated water and fertilizer of moistube irrigation (MI) is not clear. Thus, to fill the research gap, a completely randomized trial design was used to study the effects of different irrigation amounts (I; to realize different I, the tube working pressure was 1 (I1), 2 (I2), 3 (I3) m) and fertilizer amounts (F, N-P-K: 20%-20%-20%; the F at a single time was 100 (F1), 200 (F2) and 300 (F3) kg/ha) on growth and yield of tomato. The results showed that with an increase in I, the photosynthetic rate (Pn) of leaves and total dry matter mass (TDM) first increased and then decreased, while the nutrition and the flavor indexes of fruit decreased. With an increase in F, the Pn of leaves, the TDM of tomato and the fruit quality increased at first and then decreased. The effects of I on the yield of tomato was higher than that of F. With an increase in I, the partial fertilizer productivity (PFP) increased at first and then decreased, and the water use efficiency (WUE) decreased by 13.96%. With an increase in F, the WUE increased at first and then decreased, and the PFP decreased by 148.97%. The conclusion based on a spatial analysis was consistent with the comprehensive evaluation of yield and water use efficiency, which showed that I2F2 was the best. [ABSTRACT FROM AUTHOR]

Freshwater resources are in a shortage in arid regions worldwide, especially in extremely arid desert areas. To solve this problem, highly saline groundwater is used for drip irrigation of desert plants. Since more irrigation infiltrating into the deep soil cannot be absorbed and utilized by desert plants, it is crucial to determine optimal water-saving irrigation regimes. In this study, we examined the effects of irrigation regimes on the soil water dynamics of two typical woody halophyte species (Haloxylon and Calligonum), and quantified the irrigation intervals and periods based on a field test of precision irrigation control in the Taklimakan Desert Highway shelterbelt. Results showed that the change in soil moisture of two species in the shallow 0–60 cm layer could be divided into a rapid decline period (1–9 d), a slow decline period (9–19 d), and a relatively stable period (19–39 d) after irrigation. The decrease rate of soil moisture at the 0–60 cm depth was significantly higher than that at the 60–200 cm depth. The irrigation regime combining 35 mm irrigation with 10 days was beneficial to soil water storage and plant use with respect to Calligonum, while the irrigation regime combining 35 mm irrigation with 40 days was best for Haloxylon. Increasing the single irrigation amount and prolonging the irrigation period can further enable the more effective use of irrigation water. This study highlights that saline groundwater irrigation provides potential advantages for desert plants' survival under reasonable irrigation regimes. [ABSTRACT FROM AUTHOR]

Activated water irrigation has been widely investigated as an effective production increasing measure. However, the response of activated water irrigation in plant growth and water use efficiency (WUE) with the irrigation amount is not well understood. Here, a pot experiment was conducted to determine the effects of activated water irrigation on winter wheat growth, yield, and WUE under irrigation amount. Twelve treatments included four irrigation water types, (i) tap water (TW), (ii) tap water with magnetization (MW), (iii) tap water with oxygenation (OW), (iv) tap water with magnetization and oxygenation (M&OW), and three irrigation amounts, (1) 80% of the field capacity (FC), (2) 65%FC, and (3) 50%FC. The results indicated that activated water irrigation improved the plant height, leaf area, aboveground biomass, and photosynthetic characteristics at each growth stage of winter wheat. However, the yield and WUE varied with water type and irrigation amount. With 80%FC, the yield and WUE of MW were significantly greater by 35.7% and 53.9% than TW. The yield and WUE of OW were greater by 11.4% and 23.1% than TW. With 65%FC, the yield of MW, OW, and M&OW were greater by 43.9%, 46.3%, and 14.6% than TW, respectively. WUE of MW, OW, and M&OW were greater by 37.0%, 37.0%, and 11.1% than TW, respectively. With 50%FC, the yield of OW and M&OW were significantly greater by 77.3% and 122.7% than TW. WUE of OW and M&OW were significantly greater by 41.4% and 75.9% than TW (p < 0.05). Overall, the research provides clear evidence that OW is an effective way to increase yield and WUE, MW and M&OW should be applied in suitable soil water conditions. [ABSTRACT FROM AUTHOR]

Aims: This study was conducted under Hatay, Turkey ecological conditions in the second crop season and aimed to determine the effect of irrigation numbers and amounts on some quality characteristics of popcorn (Zea mays everta Sturt.) Methods and Results: Antcin 98 popcorn cultivar was cultivated in Hatay Mustafa Kemal University Research Area in the second crop season of 2015 under five irrigation managements as follows: (I1) 12 times (1757 mm), (I2) 8 times (1449 mm), (I3) 6 times (1148 mm), (I4) 5 times (989 mm) and (I5) 4 times (800 mm). After harvest, quality analysis were carried out with 4 repetitions for each irrigation treatment and kernel size, crude protein, crude oil and crude ash ratios were determined. It’s revealed that all the parameters investigated significantly affected by irrigation managements. According to the results; the lowest grain size (89.00 grains 10 g-1) and the highest crude protein ratio (10.59%) were obtained from the I5 treatment, while the highest crude ash (2.04%) and crude oil (5.74%) ratios were obtained from the I4 treatment. It was determined that as the number of irrigation decreased, the crude protein ratio increased, the crude ash and crude oil ratios increased to a certain level and then decreased. With the correlation analysis performed, significant and positive relationships were determined between kernel size and crude protein (r = 0.686) and between crude oil and crude ash (r = 0.852). Conclusions: The results showed that excessive irrigations cannot increase kernel size, which directly affects the popping volume, which is one of the most important quality criteria of popcorn, However, the nutritional values can be changed by applying different irrigation managements. It can be concluded that under similar growing and climatic conditions, popcorn can be produced with 5 irrigations and a total of 989 mm of irrigation water. Significance and Impact of the Study: The study revealed the effects of different irrigation numbers and amounts on some quality characteristics of popcorn grown under second crop season conditions. [ABSTRACT FROM AUTHOR]

Temperature in greenhouse is often elevated during tomato(Lycopersicon esculentum L.) plants growing season, which causes the change of crop water requirement. With the climate change, high temperature episodes will become much more common. Tomato seedlings were treated by 80% ETc (Evapotranspiration), 100% ETc and 120% ETc of irrigation amounts under elevated temperature in greenhouse. The influence of supplementary irrigation on photosynthesis and quality of seedlings were investigated. Results showed that both net photosynthetic rate (Pn) and PS II photochemical efficiency (Fv/Fm) in plants with 120% ETc irrigation were the highest, while the minimum fluorescence (Fo) was the lowest among treatments. With the decrease of Pn in treatments of 80% ETc and 100% ETc, the stomatal limitation values (Ls) increased significantly. Seedling health index and growth function showed the following trends: 120%ETc>100%ETc>80%ETc. There was a positive relationship between irrigation amount and physiological indexes in tomato seedlings exposed to elevated temperature. 80% ETc and 100% ETc worsened the effects of heat stress, while 120% ETc irrigation amount mitigated the stress and enabled plants to thrive under elevated temperature. [ABSTRACT FROM AUTHOR]

Biodegradable film (BF), as a superior substitute for traditional polyethylene film (PF), has experienced a consistent increase in China. However, a significant research gap persists regarding the utilization of BF in assessing farmland carbon balance. This experiment examined the responses of maize growth, yield, irrigation water productivity (IWP), CO 2 emissions, and field net carbon sequestration (NCS) to two BF types (BF 1 , 100-day induction period, and BF 2 , 80-day induction period), and PF, and three irrigation amounts (I 1 , I 2 , I 3 : 5250, 5625, and 6000 m3 ha–1), by conducting a two-year (2019–2020) field trial in a typical arid and semi-arid region of China. The results indicated that biodegradable film mulching (BFM) negatively affected maize growth, resulting in reduced yield and IWP. Especially under the I 1 irrigation level, the biodegradable film reduced maize yield by 6.26%–13.99% and IWP by 6.64–13.85%. Notably, in the I 2 irrigation level, BF 1 mulching had a comparable impact on maize yield and IWP to that of PF. Additionally, the increase in irrigation amounts exerted a more pronounced promoting effect on maize total biomass than on yield and IWP. Concerning carbon balance, short-term BF application resulted in reduced CO 2 emissions (5.74–6.30% under BF 1 and 9.27–12.37% under BF 2), without any significant impact on NCS in cropland. Taking into account the economic value of maize and farmland ecology, we recommended utilizing irrigation amounts of 5625 m3 ha–1 for BF application in arid areas, while opting for a BF with a longer induction period whenever feasible. • Biodegradable film mulching reduces maize yield and irrigation water productivity. • Biodegradable film mulching significantly decreases soil CO 2 emissions. • Increasing irrigation compensates for yield loss due to biodegradable film mulching. • Biodegradable film with a 100-day induction period is an ideal covering material. [ABSTRACT FROM AUTHOR]

High temperatures in summer can prevent people from using urban green spaces. Irrigating urban green spaces is a promising strategy to reduce temperatures. In this study, we aimed to a) identify the proportional contribution of different irrigation cooling mechanisms and b) quantify the impacts of different irrigation amounts (from 2 to 30 mm d−1) on the cooling effect of irrigating turfgrass in Melbourne, Australia. We first used a field experiment in Melbourne to provide empirical data to calibrate and verify the performance of an urban ecohydrological model, UT&C. Then, we used UT&C to predict the impacts of irrigating turfgrass on evapotranspiration, the energy balance and microclimate. UT&C predicted that irrigating turfgrass 4 mm d−1 would increase the evaporation from grass canopy and soil surface by 0.2 and 0.6 mm d−1, respectively, whereas it would reduce transpiration by 0.6 mm d−1 due to intercepted water covering part of the grass canopy following the irrigation. UT&C predicted that daytime (10:00–16:59) mean air temperature reductions would increase from 0.2 to 0.4 °C when the irrigation amount increased from 2 to 4 mm d−1. However, increasing the irrigation amount beyond 4 mm d−1 would not increase the cooling benefits. [Display omitted] • We measured the cooling effects of irrigating urban green spaces. • We used a model to identify cooling mechanisms and optimal ideal irrigation amount. • Irrigating grass increased evaporation from soil surface and canopy interception. • Increasing irrigation amount beyond 4 mm d−1 would not strengthen cooling effect. • Irrigating grass 4 mm d−1 significantly reduced daytime air temperature by 0.4 °C. [ABSTRACT FROM AUTHOR]

The mechanism of greenhouse tomato growth and yield under the integrated water and fertilizer of moistube irrigation (MI) is not clear. Thus, to fill the research gap, a completely randomized trial design was used to study the effects of different irrigation amounts (I; to realize different I, the tube working pressure was 1 (I1), 2 (I2), 3 (I3) m) and fertilizer amounts (F, N-P-K: 20%-20%-20%; the F at a single time was 100 (F1), 200 (F2) and 300 (F3) kg/ha) on growth and yield of tomato. The results showed that with an increase in I, the photosynthetic rate (Pn) of leaves and total dry matter mass (TDM) first increased and then decreased, while the nutrition and the flavor indexes of fruit decreased. With an increase in F, the Pn of leaves, the TDM of tomato and the fruit quality increased at first and then decreased. The effects of I on the yield of tomato was higher than that of F. With an increase in I, the partial fertilizer productivity (PFP) increased at first and then decreased, and the water use efficiency (WUE) decreased by 13.96%. With an increase in F, the WUE increased at first and then decreased, and the PFP decreased by 148.97%. The conclusion based on a spatial analysis was consistent with the comprehensive evaluation of yield and water use efficiency, which showed that I2F2 was the best.

This experiment aimed to determine the crop evapotranspiration (ETc) and groundwater input in total water used by wheat (Triticum aestivum) crop and to use the CROPWAT model to predict the crop ETc. To estimate the on-field ETc and groundwater contribution, the combining lysimeter technique was used. The water levels below the soil surface were kept at 1.60, 2.20, and 2.80 m and each water table depth was replicated three times. A field experiment was conducted under silt loam (SL) and silty-clay loam (SCL) soil conditions. The climatic parameters and water balance components were recorded accordingly. The on-field ETc was compared with the predicted ETc by CROPWAT model. Under SL soil, the observed ETc was 442, 427 and 401 mm and under SCL soil conditions it was observed as 419, 402 and 389 mm at the water table depth of 1.60, 2.20, and 2.80 m, respectively. The ETc was reduced with an increase in water level below the surface. The groundwater contribution under SL and SCL soil was observed as 50%, 41%, and 30% and 43%, 34%, and 24%, at 1.60, 2.20 and 2.80 m water table depth, respectively. The predicted ETc by CROPWAT model for SL and SCL soil conditions was 428.8 and 410.7 mm, respectively. The projected ETc was equal to the average ETc observed under lysimeter experiment. Thus, the use of CROPWAT model is recommended to overcome waterlogging and salinity problems and to conserve water resources. Considering lysimeter results, the irrigation applications must be revised for shallow water table levels due to adequate contribution of groundwater. [ABSTRACT FROM AUTHOR]

The development of irrigated agriculture in northwest China is restricted by shortages of fresh water and groundwater salinization. Saline water irrigation may cause salt accumulation in the soil, which results in salt stress to roots. The effects of water salinity and irrigation amount on wheat root distribution and yield, as well as soil salt distribution, were evaluated in field experiments conducted in 2014 and 2015 at the Shiyanghe Experimental Station of the China Agricultural University (102°52'E, 37°52'N), located in the Liangzhou District, in the city of Wuwei in northwest China. A total of 12 treatments including 4 levels of irrigation water salinity as indicated by electrical conductivity (0.65, 3.2, 5.2, and 7.1 dSm-1) and 3 levels of irrigation amount (205, 280, and 355 mm), were established using a randomized block design. Freshwater with an electrical conductivity of 0.65 dSm-1 and an irrigation amount of 355 mm was used as the control for salinity and irrigation level. The results showed that the influence of irrigation amount and water salinity on root distribution was mainly in the top 40-cm. Irrigation amount had no statistically significant (p > 0.05) effects on the average root length density (RLD) in the 2-year experiment. A decrease in irrigation amount reduced root biomass (RB) at maturity when water salinity ranged from 0.65 to 5.2 dSm-1. Water salinity less than 3.2 dSm-1 stimulated root growth in the soil layers 10-40-cm at the heading stage without obvious yield reduction or salt accumulation. However, water salinities of 5.2 and 7.1 dSm-1 led to decreases in RLD in the 0-10-cm layer and RB at the maturity stage, and a significant decrease in yield (p < 0.05) in both years. The interaction effects of irrigation amount and water salinity had no statistically significant (p > 0.05) effects on root parameters and yield. In the absence of rainfall, a regime with irrigation amounts between 205 and 355 mm and water salinity between 0.65 and 5.2 dSm-1 can ensure a 70% yield. [ABSTRACT FROM AUTHOR]

Activated water irrigation has been widely investigated as an effective production increasing measure. However, the response of activated water irrigation in plant growth and water use efficiency (WUE) with the irrigation amount is not well understood. Here, a pot experiment was conducted to determine the effects of activated water irrigation on winter wheat growth, yield, and WUE under irrigation amount. Twelve treatments included four irrigation water types, (i) tap water (TW), (ii) tap water with magnetization (MW), (iii) tap water with oxygenation (OW), (iv) tap water with magnetization and oxygenation (M&OW), and three irrigation amounts, (1) 80% of the field capacity (FC), (2) 65%FC, and (3) 50%FC. The results indicated that activated water irrigation improved the plant height, leaf area, aboveground biomass, and photosynthetic characteristics at each growth stage of winter wheat. However, the yield and WUE varied with water type and irrigation amount. With 80%FC, the yield and WUE of MW were significantly greater by 35.7% and 53.9% than TW. The yield and WUE of OW were greater by 11.4% and 23.1% than TW. With 65%FC, the yield of MW, OW, and M&OW were greater by 43.9%, 46.3%, and 14.6% than TW, respectively. WUE of MW, OW, and M&OW were greater by 37.0%, 37.0%, and 11.1% than TW, respectively. With 50%FC, the yield of OW and M&OW were significantly greater by 77.3% and 122.7% than TW. WUE of OW and M&OW were significantly greater by 41.4% and 75.9% than TW (p < 0.05). Overall, the research provides clear evidence that OW is an effective way to increase yield and WUE, MW and M&OW should be applied in suitable soil water conditions.

Desertification control is an important issue that must be considered in modern society. In order to effectively improve the accuracy and practicability of the evaluation algorithm of desertification control effect, the Alhagi sparsifolia index under different irrigation amount was taken as the research object, and the evaluation algorithm of desertification control effect was proposed. In the "vegetation-sandstorm-soil" index system, a number of indexes were selected according to the core environmental parameters of Alhagi sparsifolia and grassland desertification. And the analytic hierarchy process, remote sensing, geographic information system, and landscape technology were used to assign index weights of desertification control capacity, which were calculated by multiple discriminant matrices. Finally, the data regression analysis was performed based on remote sensing and computer image information screening and processing to determine the final evaluation results. The experimental data show that the true positive rate of the algorithm in this paper is between 160 and 200, which is within a large range of advantages, indicating that the overall evaluation accuracy of the algorithm is high and the evaluation effect is perfect. [ABSTRACT FROM AUTHOR]

Water and nitrogen (N) are two of the most important inputs for high maize yields. An experiment was carried out in random group design to study the effects of irrigation amount and frequency on NO3--N distribution and crop water use efficiency in maize field under film-hole irrigation in 2012 and 2013 and compare and analyze water consumption between film-hole and border irrigation. There were three irrigation amount treatments, which were 37.48mm, 52.47mm and 67.47mm, and three irrigation frequency, which were 3,4,5 frequencies during the planting period under film-hole irrigation. In addition, there was also a border irrigation treatment with 67.47mm and 5 irrigation frequencies as control group. The research results showed that, NO3--N concentration in 80-100cm soil layers increased with irrigation water increase especially in maize jointing and heading stage under the same irrigation frequency. And NO3--N concentration peak of 5 irrigation frequencies appeared at 50cm soil layers, however, that of 3 and 4 irrigation frequencies appeared at 40cm soil layers. Moreover, film-hole irrigation can transform soil ineffective evaporation into effective crops transpiration and improve crop production efficiency as compared with border irrigation. To summarize, taking maize yield, crop water use efficiency and economic benefit of water using into consideration, one-time irrigation amount of 52.47mm and 4 irrigation frequencies are recommended to be used in film-hole irrigation. [ABSTRACT FROM AUTHOR]

The characteristics of the growth of winter wheat are the basis for determining a reasonable amount of irrigation water, regulating wheat growth, improving environmental conditions and increasing yield. Plant height, leaf area index (LAI), dry-matter accumulation (DMA) and harvest index (HI) are commonly used as indices of the growth of winter wheat, and growing degree days (GDD) is an important meteorological factor affecting these indices. The characteristics of plant height, LAI and dry-matter accumulation of winter wheat in 50 regions of China were analyzed based on qualitative analyses and quantitative calculations. Normalized logistic models were used to analyze the growth indices based on GDD, and we discuss the relationships between maximum LAI, HI and irrigation amount. The rate of increase in the height of winter wheat increased with GDD and was low in the early stages, high in the intermediate stages and low in the late stages. Plant height was highest when GDD increased to about 1200 °C. LAI first increased and then decreased, and the trends of change of LAI were similar among the regions. LAI was highest when GDD increased to about 1200 °C. LAI was near its maximum when plant height was near its maximum, but dry-matter accumulation still increased with GDD. The rate of dry-matter accumulation was highest when GDD was about 1200 °C. Plant height and LAI were near their maxima, but nutrients were mainly supplied to the booting and filling stages, which maintained the accumulation of dry matter. A quadratic polynomial function could describe the relationship between HI and maximum LAI. The optimal HI was 0.45 when maximum LAI was 6.5. The relationship between the maximum LAI and irrigation amount was also described by a quadratic polynomial function. Maximum LAI was 6.45 when irrigation amount throughout the growth period was 466.4 mm, when HI was approximately optimal. The growth of winter wheat in China could be simulated by GDD and a normalized logistic model, and maximum LAI and irrigation amount for the optimal HI could be obtained. This study provides a theoretical basis and an available method for predicting the yield of winter wheat and improving other models of crop growth. [ABSTRACT FROM AUTHOR]

Achieving optimal balance between maize yield and water use efficiency is an important challenge for irrigation maize production in arid areas. In this study, we conducted an experiment in Xinjiang China in 2016 and 2017 to quantify the response of maize yield and water use to plant density and irrigation schedules. The treatments included four irrigation levels: 360 (W1), 480 (W2), 600 (W3), and 720 mm (W4), and five plant densities: 7.5 (D1), 9.0 (D2), 10.5 (D3), 12.0 (D4), and 13.5 plants m−2 (D5). The results showed that increasing the plant density and the irrigation level could both significantly increase the leaf area index (LAI). However, LAI expansion significantly increased evapotranspiration (ETa) under irrigation. The combination of irrigation level 600 mm (W3) and plant density 12.0 plants m−2 (D4) produced the highest maize yield (21.0–21.2 t ha−1), ETa (784.1–797.8 mm), and water use efficiency (WUE) (2.64–2.70 kg m−3), with an LAI of 8.5–8.7 at the silking stage. The relationship between LAI and grain yield and evapotranspiration were quantified, and, based on this, the relationship between water use and maize productivity was analyzed. Moreover, the optimal LAI was established to determine the reasonable irrigation level and coordinate the relationship between the increase in grain yield and the decrease in water use efficiency.

The characteristics of the growth of winter wheat are the basis for determining a reasonable amount of irrigation water, regulating wheat growth, improving environmental conditions and increasing yield. Plant height, leaf area index (LAI), dry-matter accumulation (DMA) and harvest index (HI) are commonly used as indices of the growth of winter wheat, and growing degree days (GDD) is an important meteorological factor affecting these indices. The characteristics of plant height, LAI and dry-matter accumulation of winter wheat in 50 regions of China were analyzed based on qualitative analyses and quantitative calculations. Normalized logistic models were used to analyze the growth indices based on GDD, and we discuss the relationships between maximum LAI, HI and irrigation amount. The rate of increase in the height of winter wheat increased with GDD and was low in the early stages, high in the intermediate stages and low in the late stages. Plant height was highest when GDD increased to about 1200 °C. LAI first increased and then decreased, and the trends of change of LAI were similar among the regions. LAI was highest when GDD increased to about 1200 °C. LAI was near its maximum when plant height was near its maximum, but dry-matter accumulation still increased with GDD. The rate of dry-matter accumulation was highest when GDD was about 1200 °C. Plant height and LAI were near their maxima, but nutrients were mainly supplied to the booting and filling stages, which maintained the accumulation of dry matter. A quadratic polynomial function could describe the relationship between HI and maximum LAI. The optimal HI was 0.45 when maximum LAI was 6.5. The relationship between the maximum LAI and irrigation amount was also described by a quadratic polynomial function. Maximum LAI was 6.45 when irrigation amount throughout the growth period was 466.4 mm, when HI was approximately optimal. The growth of winter wheat in China could be simulated by GDD and a normalized logistic model, and maximum LAI and irrigation amount for the optimal HI could be obtained. This study provides a theoretical basis and an available method for predicting the yield of winter wheat and improving other models of crop growth. [ABSTRACT FROM AUTHOR]

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Although numerous studies have investigated the individual effects of salinity, irrigation and fertilization on soil microbial communities, relatively less attention has been paid to their combined influences, especially using molecular techniques. Based on the field of orthogonal designed test and deoxyribonucleic acid sequencing technology, the effects of saline water irrigation amount, salinity level of irrigation water and nitrogen (N) fertilizer rate on soil bacterial community structure were investigated. The results showed that the irrigation amount was the most dominant factor in determining the bacterial richness and diversity, followed by the irrigation water salinity and N fertilizer rate. The values of Chao1 estimator, abundance-based coverage estimator and Shannon indices decreased with an increase in irrigation amount while increased and then decreased with an increase in irrigation water salinity and N fertilizer rate. The highest soil bacterial richness and diversity were obtained under the least irrigation amount (25 mm), medium irrigation water salinity (4.75 dS/m) and medium N fertilizer rate (350 kg/ha). However, different bacterial phyla were found to respond distinctively to these three factors: irrigation amount significantly affected the relative abundances of Proteobacteria and Chloroflexi; irrigation water salinity mostly affected the members of Actinobacteria, Gemmatimonadetes and Acidobacteria; and N fertilizer rate mainly influenced the Bacteroidetes' abundance. The results presented here revealed that the assessment of soil microbial processes under combined irrigation and fertilization treatments needed to be more careful as more variable consequences would be established by comparing with the influences based on an individual factor, such as irrigation amount or N fertilizer rate. [ABSTRACT FROM AUTHOR]

• Drip irrigation frequency, amount and fertilizer rate effects on potato were studied. • Irrigation frequency had extremely significant effects on potato growth, yield and quality. • Full irrigation 1.0 ET c obtained the highest yield, quality and partial factor productivity. • Yield and WUE increased as the amount of fertilizer increased. • The best combination of three factors for multi-objective optimization was put forward. 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 (D 4), once every 8 days (D 8) and once every 10 days (D 10). The irrigation levels consisted of full irrigation (1.0 ET c , ET c is the crop evapotranspiration), medium irrigation (0.8 ET c) and low irrigation (0.6 ET c). The fertilizer (N-P 2 O 5 -K 2 O) levels included low fertilization (F 1, 100-40-150 kg ha−1), medium fertilization (F 2 , 150-60-225 kg ha−1) and high fertilization (F 3 , 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 ET c). 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 D 8 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 (D 8), full irrigation(1.0 ET c and high fertilizer (N-P 2 O 5 -K 2 O) rate (F 3 , 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. [ABSTRACT FROM AUTHOR]

In water-scarce regions, alternate-furrow irrigation (AFI)—alternately wetting half of the plant roots—has proven to be an effective water-saving approach without compromising yield. However, the extent to which AFI with wastewater affects N cycling genes remains poorly studied. We aimed to investigate changes in main N transformation processes, bacterial and fungal community composition, as well as relative abundance of N cycle-associated genes in soil receiving AFI with swine wastewater. The experimental plan included three irrigation rates, irrigating pepper plants with 50%, 65%, and 80% of the amount of water required under conventional furrow irrigation to prevent the crop suffering water stress. Each treatment had a groundwater irrigation control. We measured edaphic factors, microbial community composition, and relative abundance of genes in rhizosphere and bulk soils. Altering water use in AFI did not exert a significant effect on bacterial and fungal communities. By increasing the irrigation rate of wastewater, relative abundances of nifH, bacterial and archaeal amoA and nosZ genes decreased, whereas those of nirK and nirS genes increased in the rhizosphere soil; nitrification rate did not decrease and the denitrification rate remained unchanged in both rhizosphere and bulk soil, implying that appropriate increase of wastewater use by AFI can improve N use efficiency. [ABSTRACT FROM AUTHOR]

Highlights • The interactions between soil water and groundwater in a paddy field-bund landscape were quantified using HYDRUS-2D. • The groundwater capillary rise contributed 26.1%–31.2% of rice ET with a shallow groundwater table. • Lateral seepage (LS) was the main pathway for water loss through the bund. • The increasing irrigation quota linearly increased percolation while hardly influenced LS. • The most decisive soil saturated hydraulic conductivities for percolation and LS were identified by sensitivity analysis. Abstract Percolation in farmland increasingly is needed to be quantified to improve water use efficiency and mitigate accompanying nutrient loss. Experiments were conducted to measure the soil properties and moisture in a consolidated paddy field-bund landscape during the rice growing season in 2014–2015. The HYDRUS-2D model simulated soil water movement in the landscape with an excellent performance. In the study, the soil properties of the bund were similar to those of the paddy field after land consolidation. Modelling results showed that most percolation in the paddy field occurred along with water input (rainfall and irrigation). Groundwater capillary rise was detected in the coupled conditions of low soil moisture in the root zone and the shallow groundwater table. Percolation accounted for 23.2%–31.3% of water input, and groundwater capillary rise contributed 26.1%–31.2% to rice evapotranspiration. The variation of the soil water content of the bund indicated that lateral infiltration from the paddy field to the bund primarily occurred in the upper bund adjacent to the field, while the lateral seepage was only found in the lower bund below the groundwater level. Vertical percolation and lateral seepage accounted for 10.5%–14.8% of water input lost through the bund, in which the lateral seepage contributed 77.6%–88.4%. Scenario simulation with the calibrated model investigated the impacts of saturated hydraulic conductivity (K s) and the irrigation amount on the percolation and lateral seepage in the landscape. The results implied that percolation increased with the increasing K s of soil. The percolation in the paddy-bund landscape and lateral seepage were most influenced by the illuvial horizon layer of the paddy field. Furthermore, a higher irrigation amount decreased the groundwater capillary rise and aggravated percolation linearly, while it had few effects on lateral seepage. The research suggests a potential adjustment in making irrigation schedules and conducting land consolidation in the rice-planting areas with shallow groundwater depths. [ABSTRACT FROM AUTHOR]

In this study, a field experiment was conducted to investigate the soil water dynamics and water percolation through the deep vadose zone. A calibrated HYDRUS‐1D model was used to simulate the process of soil water movement and the water budget. Based on the measured volumetric soil water contents, the model was well calibrated and validated. Then, we conducted scenario analyses to determine the combined effects of irrigation amount (IA), antecedent soil moisture (AM), crop evapotranspiration, and deep percolation (DP) in an irrigation event. Four IAs (5, 10, 15, and 20 cm) and three AM conditions (AM‐1, AM‐2, and AM‐3) were controlled in the scenario analyses. The results indicate that according to the Se's (effective saturation) values status and the observed or simulated depth, there could be different conclusions on the influence of DP. Under different IAs in dry (AM‐1) and medium (AM‐2) AM status, DP changed slightly; it was 0.39 and 2.47 cm in AM‐1 and 0.40 and 2.48 cm in AM‐2 for the summer maize and winter wheat crop, respectively; the AM had a crucial contribution to DP. While under the condition of wet AM (AM‐3) or small observation depth, the water inputs could have a significant effect on DP. According to increasing irrigation intensity, the higher values of Se (>0.6) in the whole profile were only displayed between 70 and 300 cm at AM‐1, 70–500 cm at AM‐2, and 70‐below 600 cm at AM‐3, which were gradually extended and moved down with increasing AM. Hence, the IA significantly affected the water percolation at a depth of 200 cm, whereas there was a weak influence at 600 cm except in AM‐3. Furthermore, in the higher values of the Se (>0.65) domain, the correlation between IA and DP was an exponential function and significantly under P < 0.05. In addition, DP began to occur when the soil water content was equal to or greater than 0.75 times that of the field water capacity or the Se > 0.65. When the coarse silt layer became embedded in the silt clay soil profile, it lagged the process of water transport but did not affect permeability in the end. [ABSTRACT FROM AUTHOR]

Abstract Livestock wastewater is rich in nutrients but may contain antibiotics and antibiotic resistance genes (ARGs). Their discharge to watercourses or soil may result in proliferation of ARGs. Irrigation with wastewater appears to be the most feasible option of disposing of it. One efficient irrigation technology used in arid regions is alternate-furrow irrigation (AFI) by alternately drying part of the plant roots for a prolonged period to physiologically reduce transpiration without compromising yield. However, the extent to which AFI with wastewater influences the concentration of antibiotics and spread of ARGs in soil is poorly understood. The purpose of this paper is to investigate how AFI using swine wastewater alters antibiotic kinetics and ARGs abundance under different irrigation rates, using pepper as the model plant. We examined three AFI treatments using 50%, 65% and 80% of the amount of water employed in sufficient conventional furrow irrigation. Each treatment had a groundwater irrigation control. The results showed that antibiotic concentrations and relative ARGs abundance in the top 20 cm of soil did not increase with the irrigation amount, although they were higher than those in the groundwater-irrigated soils. The relative ARGs abundance in the soil was modulated by irrigation amount and reducing the irrigation amount in AFI reduced ARGs dispersion only in rhizosphere. When the soil moisture was close to field capacity, ARGs were more abundant in rhizosphere than in non-rhizosphere, possibly because the rhizosphere is rich in microbes and increasing antibiotic concentrations due to an increase in irrigation rate favors antibiotic-resistant microbiome in competing for substrates. These, however, were not mirrored in the relative ARGs abundance in the roots. These results have important implications as it revealed that reducing the input of antibiotics and ARGs into soil with AFI does not necessarily reduce ARGs proliferation. Graphical abstract Unlabelled Image Highlights • First study of alternate-furrow irrigation effects on ARGs in soil • Rhizosphere was more sensitive to water source than non-rhizosphere soil. • Cd had greater influence on ARGs distribution than antibiotics. • Sulfonomides had a greater influence on ARGs distribution than tetracyclines. • Reducing irrigation amount with AFI reduced ARGs dispersion only in rhizosphere [ABSTRACT FROM AUTHOR]

Uncertainty in future availability of irrigation water and regulation of nutrient amount, management strategies for irrigation and nitrogen (N) are essential to maximize the crop productivity. To study the response of irrigation and N on water productivity and economic return of maize (Zea mays L.) grain yield, an experiment was conducted at Water Management Research Center, University of Agriculture Faisalabad, Pakistan in 2015 and 2016. Treatments included of full and three reduced levels of irrigation, with four rates of N fertilization. An empirical model was developed using observed grain yield for irrigation and N levels. Results from model and economic analysis showed that the N rates of 235, 229, 233, and 210 kg ha−1 were the most economical optimum N rates to achieve the economic yield of 9321, 8937, 5748, and 3493 kg ha−1 at 100%, 80%, 60%, and 40% irrigation levels, respectively. Economic optimum N rates were further explored to find out the optimum level of irrigation as a function of the total water applied using a quadratic equation. The results showed that 520 mm is the optimum level of irrigation for the entire growing season in 2015 and 2016. Results also revealed that yield is not significantly affected by reducing the irrigation from full irrigation to 80% of full irrigation. It is concluded from the study that the relationship between irrigation and N can be used for efficient management of irrigation and N and to reduce the losses of N to avoid the economic loss and environmental hazards. The empirical equation can help farmers to optimize irrigation and N to obtain maximum economic return in semi-arid regions with sandy loam soils. [ABSTRACT FROM AUTHOR]

A sustainable agricultural system depends on good soil quality and crop performance. However, information is limited about the influence of long-term irrigation schedules on soil properties and crop performance on fields without crop residue incorporation or machine tillage. In this study, we investigated the changes of soil bulk density (BD), saturated hydraulic conductivity (Ksat), water-stable aggregate, soil organic matter (SOM), and total nitrogen (TN) at the depths of 0 to 5, 5 to 10, 10 to 20, and 20 to 40 cm relative to different irrigation amounts based on a 17-year-long experiment in a double-cropping system with crop residue removed and manual tillage in the North China Plain. Results showed that BD increased as the irrigation amount increased. Saturated hydraulic conductivity reached a maximum level at a moderate irrigation level. Irrigation timing also affected soil BD and Ksat. Water-stable aggregates did not show consistent trends. Soil organic matter and TN showed similar decreasing trends with increased irrigation amount. No significant relationships were found between soil physical properties and grain yield. However, SOM did affect crop production significantly. Overall, results indicated that continuous irrigation without crop residue return negatively affected soil properties and crop performance. Soil quality and crop production may benefit from a reasonable irrigation strategy and the return of crop residue to the field. [ABSTRACT FROM AUTHOR]

Based on loam soil in different design density 1.4 g/cm3, 1.5 g/cm3, 1.6 g/cm3, we had done the test of the changes relationship between the soil containing water and the soil water potential, and analyzed the soil water potential trends of the loam soil in the design of different bulk density. The results show that the value of loam soil water potential is in the range of 57 to 140 kpa under the same soil containing water (gravimetric water content 12.5%) and the design of three soil bulk density, and present that the greater the soil bulk density, the smaller the soil water potential. The changing range of them is in trend of decreasing. All of these experimental studies will be benefit to choose the suitable discharge of the dripper for drip irrigation system, and make full use of the natural energy of the soil water potential, using it as the control index of irrigation system. At the same time, these results can provides a theoretical basis further for researching on the crop root zone soil moisture migration regularity and determining the optimal soil moisture environment. [ABSTRACT FROM AUTHOR]

This study aimed to determine the effect of irrigation amount and irrigation frequency on drip-irrigated flue-cured tobacco evapotranspiration (ETa), yield, and water use efficiency. Four irrigation treatment levels were imposed: 100% IRT (fully irrigated treatment, no stress), 85% IRT, 70% IRT, RFT (rainfed treatment), and high, medium, and low irrigation frequencies were set. The relationship between irrigation volume and yield is a quadratic curve. The evapotranspiration had a positive relationship with the irrigation amount. The yield of flue-cured tobacco was the highest in 2016 (wet year), and the corresponding ETa was the smallest. The irrigation water use efficiency (IWUE) in the driest year, 2017, was lower than IWUE in the wet years 2015 and 2016, and the crop water use efficiency (CWUE) had similar results for the three years. IWUE increased with irrigation amount. The effect of irrigation frequency on CWUE was not significant. The CWUE had a positive relationship with yield. No significant differences due to irrigation frequency were found for yield.

Understanding soil water percolation in paddy fields is helpful to optimize irrigation schedule for rice production and improve water use efficiency under various irrigation practices and groundwater depths. Calibrated HYDRUS-1D model was used to simulate soil water movement and water balance in this study. We conducted scenario analyses based on the model to evaluate the combined effects of irrigation amount in an irrigation event (irrigation amount), irrigation duration, antecedent soil moisture, and groundwater depth on deep percolation (DP) in paddy fields. Results showed that during an irrigation event, there would be higher DP in paddy fields with higher antecedent soil moisture (≥−10 kPa), larger irrigation amount (7 cm) and/or free drainage in the bottom of rice root zones. We also used a classification and regression tree model to analyze the relative contribution of different factors to DP. Results indicated that antecedent soil moisture was the primary factor that contributed 46.3% of DP variation. Groundwater depth contributed 32.5% of DP variation, while irrigation amount (18.7%) and irrigation duration (2.5%) contributed least for DP variation. Furthermore, effects of these factors on DP interacted with each other. In scenario analysis, the contribution of antecedent soil moisture increased from 16.1% to 65.2% as the groundwater depth increased. When irrigation amount rose from 1 cm to 5 cm, the contributions of antecedent soil moisture increased to 77.6% from 57.1%; when irrigation amount was 7 cm, the contributions of antecedent soil moisture decreased to 46.4%. The contribution of irrigation amount rose to 55.7% from 28.4% with the increase of antecedent soil moisture, while the contributions of groundwater depth to DP showed opposite variation to irrigation amount as antecedent soil moisture altered. Based on relative contribution of these factors, optimal combinations of irrigation practices, antecedent soil moisture and groundwater depth were screened out to control DP for promoting rice growth and improving water use efficiency. [ABSTRACT FROM AUTHOR]

Under field conditions, this study investigated the influence of the irrigation amount on olive root morphology and spatial distribution. Soil samples were taken with an auger at distances of 30, 60, and 90 cm from the tree trunks in four directions. The roots were analyzed using an Epson Twain Pro root scanning system. The results indicated that under different irrigation treatments, the indicators of root morphology of different varieties showed different responses to the irrigation amount. The root length density (RLD), root surface area (RSA), and root volume (RV) of Arbosana first increased with increasing irrigation amount but then decreased; however, those of Arbequina monotonically increased with increasing irrigation amount. The root average diameter of the two varieties was inversely proportional to the irrigation amount. In the vertical dimension, the RLD and RSA of each treatment decreased with increasing soil depth and were mainly distributed in the surface soil (0-20 cm in depth). The RLD and RSA in the vertical direction (VD) of the drip irrigation belt were higher than those of the belt in the parallel direction (PD), and the range was 12% to 86%. Compared with the roots of the 0- to 20-cm soil layer, the roots of the 20- to 40-cm and 40- to 60-cm soil layers were more influenced by the irrigation amount. Horizontally, the RLD and RSA decreased with increasing radial distance. The 30-cm radial area contained most roots, the proportion of roots in this region increased with increasing irrigation capacity. The influence of irrigation quantity in the PD of the drip irrigation belt was greater than that in the VD. The results suggest that irrigation does not change the root spatial distribution pattern but does promote root growth. The two varieties had different responses to irrigation. In terms of soil moisture levels after irrigation, 75% of field capacity is appropriate for 'Arbosana', whereas 100% is advisable for 'Arbequina'. To improve water use efficiency, moisture should be irrigated within the 30-cm radial distance from the trunk, and irrigation depth is not easy to more than 20 cm. This study provides a scientific basis for the efficient water management of olive trees. [ABSTRACT FROM AUTHOR]