Water-saving Irrigation Research Articles

Водосберегающие поливы кукурузы на мелиорированных землях Ростовской области

Purpose: to develop a water-saving regime for irrigating corn for grain, which guarantees sustainable productivity with a shortage of water resources on the basis of field research. Materials and methods. The studies were carried out in Rostov region according to generally accepted methods. The soil of the plot is ordinary chernozem. According to water-physical and agrochemical indicators, it is suitable for crop cultivation. The experiment scheme included three options: in option 1 (control), a previously developed irrigation regime was used; in options 2 and 3, from the beginning of the growing season to the phase of tasselling, irrigation rates were given out completely (as in option 1), and then decreased by 15 and 30 %, respectively. Results. The pre-irrigation soil moisture limit in the 0–60 cm layer was maintained at the level of 70–75 % of the minimum water capacity. The soil water regime influenced the plant growth and development. The differences in the onset of plant vegetation phases were observed from the phase of tasselling. The grain firm ripe stage occurred in variant 3 earlier, then in variant 2. The largest linear growth in the flowering phase (269 cm) was recorded in variant 1, which was 3.7 and 5.2 % higher than the indicators of the variants 1 and 2, respectively. The biological yield of corn in option 1 was 12.9 t/ha, which is 10.1 and 16.3 % higher than the water-saving options. According to the calculations of economic efficiency, with a decrease in irrigation rates by 15 %, the cultivation of corn for grain is profitable. Conclusions. As a result of the research, a water-saving irrigation regime for corn for grain was developed and recommended for agricultural production, which provides for nine vegetation irrigations: the first and second – 300 cubic meters/ha each, the third – 400 cubic meters/ha, from the fourth to the ninth ones, irrigation is carried out at a rate reduced by 15 % – 425 cubic meters/ha. Irrigation rate is 3550 cubic meters/ha.

Calculation of release time of water in soil layer

This article discusses the importance and principles of drainage system design in irrigated land. Weather and the type of cultivated crop are analyzed as the main factors for the drainage system. Also, since there is no single empirical formula for determining the duration of groundwater discharge through ditches for designing efficient and sustainable drainage systems in areas where water-saving irrigation technologies are introduced, a certain new method for determining this time is presented as a recommendation.

DIRECT SOWING IMPROVES CHLOROPHYLL CONTENT OF SILAGE MAIZE FULLY IRRIGATED WITH RECYCLED WASTE WATER BY INCREASING WATER RETENTION IN THE SOIL

Increasing fresh water shortage has revealed the use of waste water in agricultural irrigation, deficit irrigation approaches and integrated management of soil moisture with tillage-sowing practices. The crop productivity in the irrigated conditions is directly controlled by photosynthetic activities. Therefore, the effects of the irrigation with recycled domestic waste water at different irrigation water levels (100%, 67% and 33%), compared to full irrigated fresh water, on the chlorophyll content of silage maize and surface soil moisture in conventional tillage and direct sowing conditions were examined in the irrigation periods of two experimental years (2020 and 2021). The soil moisture was determined by 1.5% higher in direct sowing than in conventional tillage, and the chlorophyll content in full irrigation with waste water and the direct sowing was found by 4.9% and 1.9% higher than in full irrigation with fresh water and conventional tillage, respectively. However, chlorophyll content decreased by 20.7% and 34.0% at 33% and 67% deficit irrigation with waste water compared to full irrigation with waste water. The significant (p<0.01) linear correlation between the soil moisture and chlorophyll content showed that chlorophyll content can be managed with the soil moisture. It can have concluded that full irrigation with waste water in the direct sowing can be recommended with positive effects on the conservation of fresh water resources, effective managing soil moisture, thus saving irrigation water, increasing chlorophyll content and crop productivity.

Effects of Straw Return with Nitrogen Fertilizer Reduction on Rice (Oryza sativa L.) Morphology, Photosynthetic Capacity, Yield and Water–Nitrogen Use Efficiency Traits under Different Water Regimes

The sustainability of rice (Oryza sativa L.) cultivation has been threatened by water deficit and nitrogen (N)-fertilizer abuse. Straw return combined with N-fertilizer reduction could be an effective agronomic practice to improve N-use efficiency in rice production, but the interaction with water-saving irrigation regimes remains largely unknown. Here, a 2-year paddy field experiment was conducted to elucidate the effects of irrigation regime (continuously flooded, CF; controlled irrigation and drainage, CID) and straw return with N reduction (conventional farmers’ fertilization practice of 300 kg N ha−1 without straw return, N300; straw return with 25% N reduction, SN225; straw return with 50% N reduction, SN150) on rice growth dynamics, grain yield and water–nitrogen utilization. The results showed that CID significantly affected photosynthesis and fluorescence indicators, and increased grain yield and water productivity of rice. Straw return with N reduction reduced most rice growth traits, exhibiting lower plant height, tillers, leaf photosynthesis, chlorophyll fluorescence and dry matter accumulation, especially in vegetative growth under CF. In contrast, SN225 under CID showed compensatory effects on photosynthetic and fluorescence traits, thus improving N uptake during the reproductive growth stage. Despite a 6.6–7.1% yield reduction in SN225, 25% of N-fertilizer input was saved, with a corresponding increase in internal N-use efficiency and N-partial factor productivity. Overall, the present study indicates that straw return combined with moderate N deficiency might be a more eco-friendly and sustainable agronomic practice in water-saving irrigated rice fields.

Peningkatan Produktivitas Melalui Perbaikan Sistem Budidaya Padi Sawah Di Tengah Ancaman Perubahan Iklim

The demand for food is increasing at the same rate as the population. The government continues its efforts to increase the availability of staple foods, particularly rice, despite the threat of climate anomalies and the shrinking of paddy fields. Adaptive rice cultivation technology innovations are strongly encouraged to continue to be developed on a large scale. Application of the jajar legowo planting system in conjunction with other technological components, such as the use of varieties that are flood-tolerant, drought-tolerant, and early maturing, as well as water-saving irrigation technology, can increase rice yield. The increased productivity resulting from the implementation of jajar legowo varies between 14.7% and 21.3% across regions. Improved climate-change-adapted varieties can boost yield by up to 28%. Some efforts to eliminate the negative impacts of climate change in the agricultural sector are; i) utilizing climate change information and planting calendar information to determine planting time and the commodities; ii) selecting and developing plant species and varieties that are adaptive to climate change, including varieties that are drought tolerant, inundated tolerant, and tolerant of salinity, as well as early-aged varieties to develop climate-adaptive cropping patterns; iii) applying water-saving technologies such as intermittent irrigation systems; iv) developing soil and plant management technologies to increase plant adaptabilities such as adding organic material and biochar application; v) developing crop-livestock systems to reduce risk and optimize the use of land resources; and vi) utilizing farm protection facilities such as farming insurance (Asuransi Usaha Tani Padi/AUTP) as part of mitigation efforts.

Comparative experiment of various irrigation technologies in maize (Zea mays L.)

Development of domestic maize cultivation largely depends on the applied agrotechnics. In keeping the increase in crop increases, the goal is to minimize crop fluctuations, and there is also an important role in the proper water supply. In our country, the yield of maize is a good water supply. The yield of maize can be significantly increased by improving the water supply of the plant. In many areas there are only very few water available for professional irrigation, so it is increasingly need to focus on modern, most water-saving irrigation technologies. In our experiment, we compare two irrigation techniques. The rain-like watering with console and the solenoid valve-controlled tape drip irrigation. Our examinations extend to mapping the properties of maize that can cause changes in the effect of irrigation and, of course, to develop crop quantities available by various irrigation technologies, since these results provide the proper income for the producer. The research was carried in Szarvas, at the school experimental field of the Hungarian University of Agriculture and Life Sciences, Department of Irrigation and Melioration, in 2020.

Zeolite reduces N leaching and runoff loss while increasing rice yields under alternate wetting and drying irrigation regime

Emerging studies provide promising evidence that applying zeolite combined with water-saving irrigation could effectively retain soil nutrients and increase rice yields. However, the effects of this water-nitrogen management strategy on soil nitrogen (N) loss through leaching and runoff are unclear under field conditions. Herein, we explored the dynamics of N concentrations, quantified soil N losses through leachate and runoff, and investigated the response of reducing N loss on rice yield. A three-year field experiment (2018−2020) was conducted in Donggang city of Liaoning Province in northeast China. The field experiment used a split-plot design, including two irrigation regimes [continuously flooded irrigation (CF) and alternate wetting and drying irrigation (AWD)] as main plots, and two zeolite applications (Z0, no zeolite; Z10, 10 t ha−1 zeolite) as sub-plots, so as to quantify their effects on TN, NH4+-N, NO3−-N loss, and rice yield. Averaged across 3 years, our results showed that AWD reduced the volume of irrigation, leachate, and runoff by 22.2%, 20.8%, and 18.9%, respectively, compared with CF. AWD also decreased the losses of total N (TN), NH4+-N, and NO3−-N by 25.5%, 17.5%, and 11.1% in leachate and by 22.9%, 18.3%, and 26.3% in runoff, respectively, compared with CF. Compared to Z0, Z10 reduced the losses of TN, NH4+-N, and NO3−-N by 16.0%, 16.9%, and 19.4% in leachate and by 10.0%, 14.0%, and 5.9% in runoff, respectively. N output through leaching and runoff under AWD and Z10 was decreased by 2.1% and 2.2%, respectively, compared with CF and Z0. No significant difference was found in rice yield between CF and AWD, whereas rice yields increased 3.3% under Z10 compared with Z0. Altogether, our results highlight that the combination of zeolite and AWD can simultaneously produce more rice yield and reduce soil N losses.

INFLUENCE OF IRRIGATION SYSTEMS AND COVER CROP ON WATER PRODUCTIVITY, AND MAIZE GROWTH

A field experiment was carried out to assess the effect of different irrigation systems, which included surface drip irrigation, sub-surface drip irrigation, surface irrigation in basins and cover crop on water productivity, growth and yield of maize in a silty clay loam soil in the Nile sub-district of Babil Governorate, in the fall season 2020. The experiment was designed using the split plot arrangement according to a complete randomized block design (RCBD) with three replications. The experiment treatments included two factors: cover crop (C) includes cover crop (C1) and without the cover crop (C0), and irrigation systems (I): includes surface drip irrigation (I1) subsurface drip irrigation (I2) and surface irrigation in basins (I3). Scheduling Irrigation was applied after 50% depletion of the plant available water. The water balance equation was used to determine the water consumption of maize. The results showed that C1I3 treatment was highest mean of plant height 235 cm, grain yield 11236 kg ha-1, leaf area 6076 cm2 plant-1, and leaf area index 4.05. Whereas, C0I1 was the lowest values for the previous traits, 183 cm, 5200 kg ha-1, 3997 cm2 plants-1, and 2.67 respectively. Treatment C1I2 was superior in the value of field water use efficiency and crop water use efficiency, which reached 3.49 kg m-3 and 3.05 kg m-3, respectively. Whereas, treatment C0I1 gave the lowest value for field and crop water use efficiency, which was 1.11 kg m-3 and 1.05 kg m-3, respectively. The highest water consumption of maize was 709 mm season-1 was for treatment C0I3, and the lowest water consumption was 362 mm season-1 for the treatment C1I2. It is clear that surface drip irrigation in the presence of cover crop contributed to saving irrigation water by reducing water consumption of maize.

Spatio-Temporal Evolution of the Ecological Environment in a Typical Semi-Arid Region of Northeast China

Increasing trends of groundwater and soil salinization, as well as desertification, is characteristic of many arid and semi-arid regions under climatic and anthropogenic influences. This has led to the implementation of management strategies to protect the ecological environment. Changling County in Northeast China is a typical semi-arid area that has experienced these changes. Thus, management strategies such as the “Three North Shelterbelt Project” which involves planting trees to reduce wind speed and halt desertification, and the Changling local alkaline land restoration project, from the year 2000, involving fencing of grasslands have been implemented in the area. Premised on the dynamic nature of the ecological environmental problems, this study was undertaken to assess the spatio-temporal evolution of the ecological environment using hydro-geochemical, spatial, remote sensing, and statistical techniques from the year 2001 to 2019. It was found that groundwater salinity was stable within the period due to groundwater exploitation that declined depth to groundwater table (DWT) thus reducing the impact of evaporation concentration of salts in groundwater. Salinized land area increased by about 6706 ha at a rate of 0.06%/year as a result of the reduction in the size of water bodies and swampland as the declining water table exposed shallow water to more evaporation. The effect of the conversion of water bodies and swamplands to salinized land is believed to overshadow the climatic influence of decreased evaporation-precipitation ratio that normally decreases soil salinization. Most of the study area was stable in terms of desertification (98.22%, 56,3497 ha) as significantly degraded lands covered only 0.03% (148 ha) of the area while 1.67% (9556 ha) had significantly increased vegetation, respectively. Precipitation had an insignificant relationship with desertification with irrigation believed to be the main driver of significant vegetation improvement. Water-saving irrigation practices and the growing of salt-tolerant or semi-tolerant crop species are recommended to maximize food production while stemming the environmental degradation trend due to declining DWT.

Hydro-agro-economic optimization for irrigated farming in an arid region: The Hetao Irrigation District, Inner Mongolia

Water shortage and soil salinization are the key limiting factors in agricultural production of arid and semi-arid regions. Located in western Inner Mongolia of China, the Hetao Irrigation District (HID) is one of the top three largest irrigation districts in China. Irrigation water overuse and high level of soil salinity have curbed the agricultural productivity, adversely affected farmers’ revenues, and threatened long-term sustainability of irrigated farming in the HID. Nevertheless, opportunities still exist to improve the situation. Irrigation water allocation, salt accumulation and leaching, crop productivity and farming decisions are intrinsically connected and thus require taking a holistic approach to investigate into the interactions among all those factors and devise appropriate technological, management and policy interventions. Towards this goal, we develop an integrated hydro-agro-economic optimization model to reconcile agricultural net revenue, irrigation practices, and environmental sustainability in the HID. Positive Mathematical Programming is used for model calibration to ensure the model can replicate the base year observations of crop acreage, making the model suitable for evaluating alternative scenarios. Scenario analyses are conducted to analyze the effects of water supply reduction, reducing winter irrigation, water-saving irrigation, and crop commodity price change on optimal agricultural water management practices. Results show that water supply reduction without complementary measures increases land fallow, exacerbates soil salinization, and reduces net benefits. Winter irrigation can conserve soil moisture and increase the net salt leaching in the root zone, and a reduction in winter irrigation will incur a benefit loss to the HID. Water-saving irrigation can stabilize planting areas under water shortage but exacerbate soil salinization. Price increase of a cash crop, if it has a large area share, tends to “crowd out” grain crops growing in the same season. These results provide a holistic perspective and useful insights for water management and policy in the HID.

Drip irrigation improves spring wheat water productivity by reducing leaf area while increasing yield

To mitigate the climate change-induced water shortage and realize the sustainable development of agriculture, drip irrigation, a more efficient water-saving irrigation method, has been intensively implemented in most arid agricultural regions in the world. However, compared to traditional border irrigation, how drip irrigation affects the biophysical conditions in the cropland and how crops physiologically respond to changes in biophysical conditions in terms of water, heat and carbon exchange remain largely unknown. In view of the above situation, to reveal the mechanism of drip irrigation in improving spring wheat water productivity, paired field experiments based on drip irrigation and border irrigation were conducted to extensively monitor water and heat fluxes at a typical spring wheat field (Triticum aestivum L.) in Northwest China during 2017–2020. The results showed that drip irrigation improved yield by 10.3 % and crop water productivity (i.e., yield-to-evapotranspiration-ratio) by 15.6 %, but reduced LAI by 16.9 % in contrast with border irrigation. Under drip irrigation, the lateral development of spring wheat roots was promoted by higher soil temperature combined with frequent dry-wet alternation in the shallow soil layer (0–20 cm), which was the basis for efficient absorption of water and fertilizer, as well as efficient formation of photosynthate. Meanwhile, drip irrigation increased net radiation and decreased latent heat flux by inhibiting leaf growth, thereby increased sensible heat, causing a higher soil temperature (+1.10 ℃) and canopy temperature (+1.11 ℃). Further analysis proved that soil temperature was the key factor affecting yield formation. Based on the above conditions, the decrease in leaf distribution coefficient (−0.030) led to the decrease in evapotranspiration (−5.7 %) and the increase in ear distribution coefficient (+0.029). Therefore, drip irrigation emphasized the role of soil moisture in the soil-plant-atmosphere continuum, enhanced crop activity by increasing field temperature, especially soil temperature, and finally improved yield and water productivity via carbon reallocation. The study revealed the mechanism of drip irrigation for improving spring wheat yield, and would contribute to improving Earth system models in representing agricultural cropland ecosystems with drip irrigation and predicting the subsequent biophysical and biogeochemical feedbacks to climate change.

Effects of micro-sprinkling with different irrigation levels on winter wheat grain yield and greenhouse gas emissions in the North China Plain

Increasing scarcity of irrigation water is threatening global wheat production and sustainability. Accordingly, the water-saving irrigation regime has been strongly advocated to reduce irrigation water consumption. However, studies about greenhouse gas (GHG) emissions from the winter wheat cropping system with water-saving irrigation are rare. In this study, five irrigation regimes, wherein the supplementary irrigation brought soil water content in the 0–40 cm profile to 65% (K65) field water capacity (FC), 70% (K70) FC, 75% (K75) FC, 80% (K80) FC, and 85% (K85) FC at the joining and anthesis stages in 2019–2022. K75 improved the leaf area index at the grain-filling stage and dry matter remobilization pre-anthesis and dry matter assimilation post-anthesis. Correspondingly, 5.48–23.96% increases in grain yield were observed for K75 compared with K65, K70, and K85 treatments, mainly attributable to increased number of kernels and 1000-kernel weight. Compared with the K80 and K85 treatments, K75 treatment had the most prominent effect on the instability of soil carbon, nitrogen, and moisture content, as reflected in decreased cumulative emissions of soil N2O (5.15–15.65%) and CH4 (6.07–44.07%). It also decreased the global warming potential (6.17–19.53%). However, there were no significant differences among K65, K70, and K75 treatments. In addition, the K75 treatment decreased greenhouse gas intensity (GHGI) by 5.04–25.25% compared with K65, K70, K80 and K85 treatments. Collectively, based on the combined effects of grain yield and greenhouse gas emissions improvement, we recommend K75 as a sustainable irrigation regime that can improve grain yield and decrease greenhouse gas emissions.

Assessment of Restoration Technology in Typical Ecological Degradation Regions

In the face of increasingly severe ecological degradation in the typical fragile ecological regions around the world, many different ecological technologies (ET) have been developed. However, there is still a lack of any comprehensive analysis of these technologies and the effects of their implementation on regional ecological systems, and this largely limits the promotion of the excellent technologies and their applications. Based on the Web of Science core online database and specific literature screening criteria, 3409 papers were selected to summarize and analyze the development trends, research hotspots and regional comparisons of ecological technology effect research. Furthermore, 19 publications from 14 regions were selected to compare and analyze the effects of eight commonly applied ET: shelterbelt, artificial afforestation, water-saving irrigation, terrace, stereo-agriculture, contour tillage, ban/rest/rotational grazing and fallow/no tillage/minimum tillage. The results show four key features: (1) The research on the effect of ecological technology is still in the period of continuous development. (2) “Erosion” is the largest node in the keyword co-occurrence map of ecological technologies effect research, followed by “management”. (3) Most countries pay attention to the studies of “erosion” and “runoff”, although there are differences in research on the effects of ecological technologies in different countries. (4) The same technology could be applied to different regions but the effects varied, and the ecological technologies that have been implemented have generally achieved good restoration effects; however, the improper use of ecological technologies may bring negative consequences. This study provides important support for ecosystem restoration and improvement in the ecologically degraded areas in China and around the world, and it provides a reference for the export and introduction of excellent technologies.

Socio-economic factors influencing the adoption of low carbon technologies under rice production systems in China.

Rice (Oryza sativa L.) production, such as farmers' livelihood and the soil quality, has been identified to be strong influenced by climate change in China. However, the benefits of low carbon technologies (LCTs) are still debatable in rice production for farmers, which have been identified to tackle agricultural challenges. The choice of potential LCTs relevant to the case study is based on a literature review of previous empirical studies. Thus, the objectives of the study were to (1) investigate the public perception and preferences of LCTs in rice production of China, and (2) analyze the influences of the factors on farmer's decision in adopting LCTs in rice production. There were 555 farmer surveys from eight representative rice production counties in HP province of southern China, both the Poisson estimators and multivariate probit (MVP) approach were applied in the study. Our results show that water-saving irrigation, integrated pest management techniques and planting green manure crops in winter season were the three major LCTs adapted by farmers in rice production. The intensity and probability of LCTs adoptions were influenced by the main factors including farmers' education level, climate change awareness, machinery ownership, technical support and subsidies. There is a significant correlation among the LCTs, and the adoption of the technologies is interdependent, depicting either complementarities or substitutabilities between the practices. This study suggests that policies enhance the integration of LCTs would be central to farmers' knowledge, environmental concerns, technical service and financial support in rice production systems in China.

Combination of Water-Saving Irrigation and Nitrogen Fertilization Regulates Greenhouse Gas Emissions and Increases Rice Yields in High-Cold Regions, Northeast China.

Increased rice production, which benefitted from cropping areas expansion and continuous N applications, resulted in severe increases in greenhouse gases (GHG) emissions from 1983 to 2019 in Heilongjiang Province, China. Therefore, field trials were performed in the high-cold Harbin region, Northeast China, to determine the efficiency of incorporating water regimes with N fertilization in minimizing the impact of rice production on GHG emissions. Two water-saving irrigation strategies, intermittent irrigation (W1) and control irrigation (W2), were used relative to continuous flooding (W0), and we combined them with six fertilized treatments. Our results demonstrated that W1 and W2 significantly decreased seasonal CH4 emissions by 19.7-30.0% and 11.4-29.9%, enhanced seasonal N2O emissions by 77.0-127.0% and 16.2-42.4%, and increased significantly yields by 5.9-12.7% and 0-4.7%, respectively, compared with W0. Although trade-offs occurred between CH4 and N2O emissions, W1 and W2 resulted in significant reductions in global warming potential (GWP). Moreover, low N rates (<120 kg N ha-1) performed better in GWP than high N rates. N fertilization and irrigation regimes had remarkable effects on rice yields and GWP. In conclusion, the incorporation of W1 and a N application under 120 kg N ha-1 could simultaneously mitigate GWP while enhancing production in black soils in high-cold Northeast China.

An environmental and economic assessment of sustained cleaner production for double rice from the combination of controlled-released urea and water-saving irrigation

Controlled-released urea (CRU) and water-saving irrigation are being extensively used to obtain higher rice (Oryza sativa) yields with lower greenhouse gas emissions. However, the environmental impact potential of their combined impacts is still unknown. Two-factor experiments, nitrogen practices with urea and CRU while irrigation practices with conventional irrigation (CI) and alternate wetting-drying water-saving irrigation (AWD), were used to clarify the potential impacts in the Jianghan Plain in China. Life cycle assessment (LCA) methodology was used to examine seven environmental impact categories, including non-renewable energy depletion, global warming potential (GWP), acidification potential, eutrophication potential (EP), human toxicity potential, freshwater toxicity potential (FTP) and soil toxicity potential in addition to an economic assessment. The largest contribution allocated to the comprehensive environmental impact indices included the GWP, EP (>26.28%) and FTP (>62.14%), while the other four indices contributed little, and CRU + AWD had the lowest weighting value (0.7981). The EP was affected by N fertilizer off and on the farm (7% and 68%–71%), nitrous oxide emissions from the planting season and winter fallow (7%–12% and 8%–12%) and the FTP differed slightly among the four treatments. Net ecosystem economic benefits (NEEB) (approximately 15,541 CNY ha−1) and benefit-cost ratio (52%) of CRU + AWD was similar to those of CRU + CI, and were increased by 18%–47% and 11%–41% compared with U + CI and U + AWD, respectively. Trade-off results found the combination of CRU and AWD had the lowest environmental load with a high grain yield, economic benefits and soil organic carbon storage to enable the sustainable production of rice.

Effect of Drip Irrigation Under Mulch on Nitrogen Transport in Deep Soil Layers in an Agricultural Region of the Xiliao River Plain, China

In the agricultural region of the Xiliao River Plain, drip irrigation under mulch has been widely implemented. It not only saves irrigation water, but also changes the structure of the underlying surface of agricultural land, which affects the local hydrological cycle to a certain extent, and makes the process of nitrogen transportation in soil with new characteristics. This study analyzed the distribution of NH4-N, NO3-N, and NO2-N in different soil depths during the whole growth period under three underlying surface conditions, including drip irrigation under mulch, border irrigation, and bare area through field in-situ observation experiment, and analyzed the influence of drip irrigation under mulch on nitrogen transport in deep soil layers. The results showed that under the soil properties of the experimental area, drip irrigation under mulch creates more water to enter the deep soil layers, which was beneficial to alleviate the downward trend of local groundwater level to a certain extent. The average content of NH4-N and NO3-N under drip irrigation under mulch was higher than that under border irrigation. The average content of NH4-N under drip irrigation under mulch was 1.24 mg.kg-1 in soil depths of 80-300 cm, and 0.97 mg.kg-1 under border irrigation. The average content of NO3-N under drip irrigation under mulch was 2.73 mg.kg-1 in soil depths of 80-300 cm, and 1.99 mg.kg-1 under border irrigation. The increment of NH4-N and NO3-N distribution in deep soil layers under drip irrigation under mulch was greater than that under border irrigation, and the increment of NO3-N content is significantly greater than that under border irrigation. Soil water content has a significant impact on the contents of NH4-N and NO3-N. It indicated that compared with traditional border irrigation, drip irrigation under mulch was beneficial to alleviate the downward trend of local groundwater, but it would increase the risk of nitrogen pollution in local groundwater.

The response of agroecosystem water use efficiency to cropland change in northwest China’s Hexi Corridor

China’s rapid population growth has inevitably led to a need for cropland expansion to meet food security challenges. In arid regions such an expansion is restricted by limited water resources, and an increase in productivity per cropland area must be achieved while still limiting water use. However, the response of agroecosystem Water Use Efficiency (WUEa.e.) to alterations in cropland use in Northwest China’s Hexi Corridor has not been documented in any great detail. This has limited our understanding of the region’s water-carbon interactions and, in particular, how effective cropland management and efficient water utilization protocols might be applied there. The response of the region’s WUEa.e. to different potential shifts in cropland was evaluated by drawing on growing season (2003–2020), Gross Primary Productivity (GPP) and actual evapotranspiration (ETcact) data. Over this period net cropland area increased, with 12.3 % of total cropland transferred in, but only 2.5 % of cropland transferred out. The trend in growing season WUEa.e. was greatest in cropland regions transferred in (p < 0.05), and lowest in the cropland transferred out, indicating irrigation and field management in cropland could ensure that WUEa.e. could be maintained at a higher level. Among the different cropland transformation types, the impact of cropland change on WUEa.e. was essentially determined by shifting correlations between GPP and ETcact. This correlation was weakened when the water supply increased, heightening the negative impact of ETcact on WUEa.e., while weakening the positive impact of GPP on WUEa.e.. There was a tradeoff point for the level of irrigation between improving WUEa.e. and crop yield. Suitable water-saving irrigation is crucial to maintaining a relatively high level of WUEa.e., yet not decreasing crop yield. Water-saving irrigation in the Shiyang River basin was deemed to have limited potential, whereas in the Shule River and Heihe River basins there remains some potential for such irrigation. The present study’s results can potentially inform agricultural water and land management in the region, and provide the basis for efficient water resources utilization.

Subsurface irrigation with ceramic emitters: Optimal working water head improves yield, fruit quality and water productivity of greenhouse tomato

Greenhouses are widely used in Northwest China, especially for tomato, which is the dominant crop. Subsurface irrigation with ceramic emitters (SICE) is a new water-saving technology for continuous low-rate water supply at constant soil moisture. However, a lack of knowledge still existed to define the suitable working water head for SICE to decrease water loss and promote tomato production, fruit quality, and water productivity. In this study, a greenhouse experiment was conducted during spring and autumn cultivation periods under SICE for five working water heads of 0.1 m to 0.5 m with intervals of 0.1 m and subsurface drip irrigation (SDI). The verified HYDRUS-2D model evaluated water balance components and water productivity. A structural equation model (SEM) was developed to determine interactive impacts of SICE and meteorological conditions in greenhouse on tomato yield, fruit quality, and water productivity. The results showed that SICE with a working water head of 0.4 m could be recommended, which created a suitable soil water content of the root zone within 70%–80% of field capacity (FC), resulting in a reduction of water loss from actual evaporation (Ea) and deep percolation (DP) by 12.32% and 21.88% respectively relative to SDI. Fruit weight, yield, water use efficiency (WUE), and irrigation water use efficiency (IWUE) were increased by 8.96%, 8.03%, 19.44%, and 16.05% respectively compared to SDI. Moreover, soluble sugar, organic acid, lycopene, vitamin C, and sugar acid ratio were enhanced by 2.41%, 12.19%, 14.40%, and 2.67% under SICE with the suggested working water head respectively compared with SDI. We recommended that supplemental lighting combined with SICE in autumn cultivation was necessary to ensure tomato production and fruit quality. This study provides an alternative water-saving irrigation method for greenhouse growers to maintain tomato yield and fruit quality in Northwest China.

Transcriptome analysis reveals key drought-stress-responsive genes in soybean.

Drought is the most common environmental stress and has had dramatic impacts on soybean (Glycine max L.) growth and yield worldwide. Therefore, to investigate the response mechanism underlying soybean resistance to drought stress, the drought-sensitive cultivar "Liaodou 15" was exposed to 7 (mild drought stress, LD), 17 (moderate drought stress, MD) and 27 (severe drought stress, SD) days of drought stress at the flowering stage followed by rehydration until harvest. A total of 2214, 3684 and 2985 differentially expressed genes (DEGs) in LD/CK1, MD/CK2, and SD/CK3, respectively, were identified by RNA-seq. Weighted gene co-expression network analysis (WGCNA) revealed the drought-response TFs such as WRKY (Glyma.15G021900, Glyma.15G006800), MYB (Glyma.15G190100, Glyma.15G237900), and bZIP (Glyma.15G114800), which may be regulated soybean drought resistance. Second, Glyma.08G176300 (NCED1), Glyma.03G222600 (SDR), Glyma.02G048400 (F3H), Glyma.14G221200 (CAD), Glyma.14G205200 (C4H), Glyma.19G105100 (CHS), Glyma.07G266200 (VTC) and Glyma.15G251500 (GST), which are involved in ABA and flavonoid biosynthesis and ascorbic acid and glutathione metabolism, were identified, suggesting that these metabolic pathways play key roles in the soybean response to drought. Finally, the soybean yield after rehydration was reduced by 50% under severe drought stress. Collectively, our study deepens the understanding of soybean drought resistance mechanisms and provides a theoretical basis for the soybean drought resistance molecular breeding and effectively adjusts water-saving irrigation for soybean under field production.