Traditional Flood Irrigation Research Articles

Nitrogen and phosphorus losses by surface runoff and soil microbial communities in a paddy field with different irrigation and fertilization managements.

Rice cultivation usually involves high water and fertilizer application rates leading to the nonpoint pollution of surface waters with phosphorus (P) and nitrogen (N). Here, a 10-year field experiment was conducted to investigate N and P losses and their impact factors under different irrigation and fertilization regimes. Results indicated that T2 (Chemical fertilizer of 240 kg N ha-1, 52 kg P ha-1, and 198 kg K ha-1 combined with shallow intermittent irrigation) decreased N loss by 48.9% compared with T1 (Chemical fertilizer of 273 kg N ha-1, 59 kg P ha-1, and 112 kg K ha-1 combined with traditional flooding irrigation). The loss ratio (total N loss loading/amount of applied N) of N was 9.24-15.90%, whereas that of P was 1.13-1.31% in all treatments. Nitrate N (NO3--N) loss was the major proportion accounting for 88.30-90.65% of dissolved inorganic N loss through surface runoff. Moreover, the N runoff loss was mainly due to high fertilizer input, soil NO3--N, and ammonium N (NH4+-N) contents. In addition, the N loss was accelerated by Bacteroidetes, Proteobacteria, Planotomycetes, Nitrospirae, Firmicutes bacteria and Ascomycota fungi, but decreased by Chytridiomycota fungi whose contribution to the N transformation process. Furthermore, T2 increased agronomic N use efficiency (AEN) and rice yield by 32.81% and 7.36%, respectively, in comparison with T1. These findings demonstrated that T2 might be an effective approach to ameliorate soil chemical properties, regulate microbial community structure, increase AEN and consequently reduce N losses as well as maintaining rice yields in the present study.

Mulched drip irrigation increases cotton yield and water use efficiency via improving fine root plasticity

The morphological characteristics of crop roots, especially the plasticity of fine roots, are directly related to the crop’s ability to obtain soil water. Mulched drip irrigation can effectively regulate soil water distribution to achieve high cotton yield with reduced water consumption. In the previous study, from the perspective of root-shoot coordination, we found that mulched drip irrigation reduced the growth redundancy of roots and improved the root productivity of cotton, thus achieving the goal of water-saving and increased yield. However, it is unclear if and how mulched drip irrigation enhances absorptive capacity of roots via regulating dry and wet soil areas and optimizing fine root morphology and distribution compared with traditional flood irrigation. To achieve this, the effects of fine root plasticity on the absorptive capacity of roots were studied in a two-year field experiment. Mulched drip irrigation (conventional drip irrigation and excessive drip irrigation) and traditional flood irrigation (reduced flood irrigation and conventional flood irrigation) were used, and soil water distribution and root distribution were determined. The results showed that compared with traditional flood irrigation, mulched drip irrigation significantly increased the soil water content (SWC) in the 0–60 cm soil layer and reduced the fluctuation amplitude of SWC at the flowering and boll stage of cotton. Mulched drip irrigation formed different dry and wet areas in the root zone, i.e., the SWC was higher in the shallow layer (0–40 cm) at 0–20 cm on both sides of the drip line, and most of the cotton roots were in the wet area. The higher SWC increased the distribution of fine roots in this area and shaped the shallow fine root system, which enhanced the cotton plant’s ability to absorb soil water. Statistical analysis showed that the higher fine root biomass in the 0–40 cm soil layer at the late full boll stage of cotton under mulched drip irrigation was beneficial to increase aboveground biomass, thus increasing total bolls and seed cotton yield. However, compared with the irrigation amount of field production (390 mm), an excessive amount of irrigation (600 mm) reduced the seed cotton yield of mulched drip irrigation, resulting in the decrease of irrigation water use efficiency (IWUE). Therefore, mulched drip irrigation optimizes the distribution of fine roots and enhances water uptake by effectively regulating the water–root relationship, and thus improves seed cotton yield and IWUE.

The water-saving potential of using micro-sprinkling irrigation for winter wheat production on the North China Plain

The shortage of groundwater resources is a considerable challenge for winter wheat production on the North China Plain. Water-saving technologies and procedures are thus urgently required. To determine the water-saving potential of using micro-sprinkling irrigation (MSI) for winter wheat production, field experiments were conducted from 2012 to 2015. Compared to traditional flooding irrigation (TFI), micro-sprinkling thrice with 90 mm water (MSI1) and micro-sprinkling four times with 120 mm water (MSI2) increased the water use efficiency by 22.5 and 16.2%, respectively, while reducing evapotranspiration by 17.6 and 10.8%. Regardless of the rainfall pattern, MSI (i.e., MSI1 or MSI2) either stabilized or significantly increased the grain yield, while reducing irrigation water volumes by 20–40%, compared to TFI. Applying the same volumes of irrigation water, MSI (i.e., MSI3, micro-sprinkling five times with 150 mm water) increased the grain yield and water use efficiency of winter wheat by 4.6 and 11.7%, respectively, compared to TFI. Because MSI could supply irrigation water more frequently in smaller amounts each time, it reduced soil layer compaction, and may have also resulted in a soil water deficit that promoted the spread of roots into the deep soil layer, which is beneficial to photosynthetic production in the critical period. In conclusion, MSI1 or MSI2 either stabilized or significantly increased grain yield while reducing irrigation water volumes by 20–40% compared to TFI, and should provide water-saving technological support in winter wheat production for smallholders on the North China Plain.

Sprinkler irrigation in the production of safe rice by soils heavily polluted by arsenic and cadmium

Among the factors affecting the bioaccumulation of As and Cd in rice, a key role is played by the irrigation methods. The sprinkler irrigation (SP), optimized for rice in Sardinia, Italy, applied to several rice genotypes over many years has produced no differences in yields in comparison to what observed using the traditional continuous flooding irrigation method (CF). Because all the previous SP trials have been performed just on one, unpolluted soil, the principal aim of this study is to ascertain the effectiveness of SP to simultaneously minimize the bioaccumulation of As and Cd in rice grain even in soils severely polluted by As and/or Cd. Hence, a Carnise rice genotype was cultivated in an open field in: i) an unpolluted soil; ii) a soil polluted with 55 mg kg−1 of As; iii) a soil polluted with 40 mg kg−1 of Cd; iv) a soil polluted with 50 mg kg−1 of As and 50 mg kg−1 of Cd. In the worst condition of pollution, the amounts of total As and Cd measured in the kernels using a fully validated ICP-MS method is 90 ± 10 μg kg−1 and 50 ± 20 μg kg−1, respectively, i.e. less than 50% and the 25% of the maximum concentration set for these elements in rice by the European Community (200 μg kg−1 for the inorganic As and the total amount of Cd, respectively). SP might represent a simple and valuable tool able to produce safe rice also from soils where the traditional irrigation might produce inedible rice only.

Parameterization and modeling of paddy rice (Oryza sativa L. ssp. japonica) growth and water use in cold regions: Yield and water-saving analysis

Rice is the high-water consumption crop that feeds more than half of the world population. The planting area of cold region rice is expanded rapidly in recent years due to the high market values, also resulting in increasing water shortages and eco-environmental problems on a regional scale. Pursuing high benefits and increasing water use efficiency become more significant both for stakeholders and managers. To understand the yield variation and water-saving potential, the specific rice model-ORYZA2000 was adopted to predict the responses of rice growth/yield and water use to the various climatic and irrigation conditions in a typical cold region of northeast China. Field experiments were conducted for the Japonica rice in cold regions (JRC) during 2018 and 2019, with detailed observations on rice growth and development. The ORYZA2000 was calibrated and validated using two-year experimental data. Simulated ponded water depth, various organ development and yield fitted well with field observations. A set of recommended values of crop parameters for JRC was obtained through the systematic parametrization, showing very specific and different characters from the varieties in warmer regions. The irrigation scheduling module was modified for adapting to the various irrigation regimes. After that, the scenario simulation with 30-year different climatic data (i.e. 1990–2019) and three different irrigation regimes (i.e. traditional flood irrigation (TFI), shallow-wet irrigation (SWI) and controlled irrigation (CTI)) were conducted using the calibrated model. Status evaluation and scenario analyses indicated that the crop yield of JRC varied significantly due to relatively large fluctuations of photothermal conditions in different years. The inter-annual potential yield varied from 6790 to 9516 kg ha−1, with an average of 8210 kg ha−1. Evaluation on water-saving scenarios indicated that adopting SWI and CTI regimes could averagely save up to 90 mm and 140 mm (20% and 30%) of irrigation water in dry years, respectively, compared with TFI regime. Overall, the obtained set of parameters for JRC could efficiently complement the parameter database for rice modeling in cold regions; meanwhile, the yield and water-saving evaluation could provide very useful information and the basis for supporting the future JRC production and water-saving management.

Did water-saving irrigation protect water resources over the past 40 years? A global analysis based on water accounting framework

Water-saving technologies have long been seen as an effective method to reduce irrigation water use and alleviate regional water shortage. However, growing reports of more severe water shortage and increasing application of water-saving technologies across the world have necessitated reassessment of agricultural water-saving. This study develops a simple method based on satellite-based ET partitions to estimate water withdrawal, water consumption and return flow from the 1980s to 2010s, and quantifies water-savings across globe and four hot-spot irrigated areas at both field and regional scales based on water accounting framework. The results show that global irrigation water flows keep increasing from the 1980s to 2010s, with over 50% increase from the expansion in irrigated lands. While water-saving technologies are found mainly applied in originally old irrigated lands, traditional flooding irrigation is still dominant in newly-developed irrigated lands. Non-beneficial water consumption (soil evaporation) is effectively reduced by water-saving technologies, but return flow has increased at the same time. At field scale, water-saving technologies fail to save water because the accumulated increased return flow is more than the accumulated decreased non-beneficial water consumption. At regional scale, however, water is saved because the return flow percolated to fresh aquifers is seen as beneficial rather than loss. At the same time, the accumulated increase of beneficial water consumption (crop transpiration) exceeds regional water savings, which explains the paradox between wide application of water-saving technologies and more severe regional water shortage. This study provides key new evidence for the paradox of irrigation efficiency and helps reconsidering water-saving technologies and their impacts on regional water resources.

Improving rice water productivity using alternative irrigation (case study: north of Iran)

Abstract Increasing population and the need for more food has made demands on water resources due to crop productions. One of the strategies for preventing the overuses of safe water resources for agriculture is to increase agricultural productivity by reducing the amount of irrigation water with a slight reduction or even maintaining the yields. Rice production in the northern region of Iran which is strategically and economically very important, requires irrigation management changing with traditional irrigation methods (flood irrigation). This study was conducted in the 2017–2018 crop season to investigate the effect of different irrigation management on water consumption, rice yield and water productivity in paddy field of Babolsar, Mazandaran, Iran. The experiment was performed in the field in a randomized complete block design with three replicates and four treatments in 12 plots. The treatments were TI (Traditional/flood Irrigation), and AI1, AI3 and AI5 (Alternative Irrigation one, three and five days after the disappearance of water from the soil surface, respectively). The number of yield components and the water productivity indexes were determined. The results of this study showed a significant difference (at 1% level) between irrigation treatments in terms of yield components including tiller number, Panicle length, filling percentage, and water productivity, but they did not have any significant effect on plant height and grain yield. The applied irrigation water for TI, AI1, AI3, and AI5 treatments was measured to be 7,940, 4,910, 4,090 and 3,290 m3/ha, respectively. The maximum yield (6.11 ton/ha) belonged to TI treatment and after that with the value of 6.02 ton/ha belonged to AI5 treatment with the least application of water. Rice water productivities for TI, AI1, AI3, and AI5 treatments were calculated to be 0.82, 1.05, 1.38 and 1.83 kg/m3, respectively. Therefore, alternate irrigation five days after the disappearance of surface water (AI5) was accepted to be the best irrigation practices among the other different irrigation management due to 56.07% reduction in water use and only 1.47% reduction in grain yield compared to control treatment.

Impact of participatory irrigation management on mulched drip irrigation technology adoption in rural Xinjiang, China

Abstract Reforms in irrigation management can make important contributions to reducing irrigation water scarcity. This paper attempts to examine the role of participatory irrigation management (PIM) in farmers’ mulched drip irrigation technology adoption decisions. It is based on a comparative analysis between government-promoted mulched drip irrigation technology (GMDIT) and localized self-governed mulched drip irrigation technology (LMDIT) in rural Xinjiang, China. Data from a survey conducted in 2017 across 739 households covering 1763 plots in Awati County in Xinjiang were used to estimate a nested logit model. The results indicate that PIM induces farmers to switch from traditional flood irrigation technology to GMDIT but does not promote the adoption of LMDIT. We conclude that promoting PIM can make an important contribution to more sustainable water use in this drought-prone area but that the self-governance of localized irrigation systems requires more attention by local governments.

The environmental fate of phenanthrene in paddy field system and microbial responses in rhizosphere interface: Effect of water-saving patterns

The effects of water-saving patterns (Semi-dry water-saving, B; Shallow-wet control irrigation, Q; Traditional flooding irrigation, C; and Moistening irrigation, S) on the environmental fate of phenanthrene (Phe) and microbial responses in rhizosphere were investigated in paddy field system. Results showed the rice grain in Q treatment was more high production and safety with less Phe residue (up to 18%–49%) than other treatments, and the residual Phe in soil declined in the order: C (14.17%) > S (13.36%) > B (5.86%)>Q (2.70%), which proves the existence of optimal water conditions for PAHs degradation and rhizosphere effect during rice cultivation. Laccase (LAC) and dioxygenase (C23O) played important roles in Phe degradation, which were significantly positively correlated with Phe dissipation rate in soil (p < 0.01). Moreover, their activities in Q treatment, rhizosphere and subsoil were higher than those in C treatment, non-rhizoshere and upper layer soil. The introduction of Phe and rice into paddy field system decreased the microorganism diversity, and promoted the activities of enzymes and some PAHs degrading bacteria, such as Delftia, Serratia, Enterobacter, Pseudomonas, norank_f_Rhodospirillaceae, norank_f_Nitrosomonadaceae and so on. According to the cluster analysis, redundancy analysis and correlation analysis between bacterial community composition and environmental factors, water-saving patterns markedly impacted the relative abundance and bacterial community structure by the regulating and controlling on environmental conditions of paddy field. The dioxygenase activity, laccase activity, oxidation-reduction potential and conductivity were the main affecting factors on Phe dissipation during growth stage of rice.

Interannual Variations of Evapotranspiration and Water Use Efficiency over an Oasis Cropland in Arid Regions of North-Western China

The efficient use of limited water resources and improving the water use efficiency (WUE) of arid agricultural systems is becoming one of the greatest challenges in agriculture production and global food security because of the shortage of water resources and increasing demand for food in the world. In this study, we attempted to investigate the interannual trends of evapotranspiration and WUE and the responses of biophysical factors and water utilization strategies over a main cropland ecosystem (i.e., seeded maize, Zea mays L.) in arid regions of North-Western China based on continuous eddy-covariance measurements. This paper showed that ecosystem WUE and canopy WUE of the maize ecosystem were 1.90 ± 0.17 g C kg−1 H2O and 2.44 ± 0.21 g C kg−1 H2O over the observation period, respectively, with a clear variation due to a change of irrigation practice. Traditional flood irrigation generally results in over-irrigation, providing more water than actual crop requirements. Unlike flood irrigation, which can infiltrate into deep soil layers, drip irrigation can only influence the shallow soil moisture, which can lead to decreases of soil moisture of approximately 27–32% and 36–42% compared with flood irrigation for shallow and deep layers, respectively. Additionally, drip irrigation decreases evapotranspiration by 13% and transpiration by 11–14%, leading to increases in ecosystem and canopy WUE of 9–14% and 11%, respectively, compared to the traditional irrigation practice. Therefore, the drip irrigation strategy is an effective method to reduce irrigation water use and increase crop WUE in arid regions. Our study provides guidance to water-saving cultivation systems and has implications for sustainable water resources management and agriculture development in water-limited regions.

Water‐saving cultivation plus super rice hybrid genotype improves water productivity and yield

AbstractLabor shortage, low water availability, and poor land use practice cause serious threats to rice (Oryza sativa L.) production around the world. Semiarid cultivation is a classical strategy for achieving high water productivity (WP) with lower labor inputs. However, it remains largely unknown whether the application of “super” or drought‐resistant hybrid rice could achieve higher economic benefits (WP and yield) under semiarid cultivation. This study attempted to combine three irrigation management systems (semiarid rice cultivation, traditional flood irrigation, and dryland cultivation) with two cultivars (Yangliangyou 6, YLY6, a super hybrid rice genotype; Hanyou 113, HY113, a drought‐resistant rice genotype), and evaluate their effects on the water‐saving ability and yield (the economic benefits). The two genotypes showed no significant differences in grain yield under the semiarid and flood irrigation, and both had a greater WP (13.8–51.8%) under semiarid cultivation than under flood irrigation. YLY6 produced more panicles (P &lt; .05), more spikelets per panicle (P &lt; .05), and higher grain yield (P &lt; .01) than HY113. Semiarid cultivation plus YLY6 showed higher stomatal conductance and net photosynthetic rate (P &lt; .05), resulting in higher biomass accumulation, grain yield, and WP compared with those under other treatments. YLY6 under semiarid cultivation had greater stem water content and leaf water potential, and thus showed improvement of leaf gas exchange characteristics. In conclusion, super hybrid rice has the potential to achieve greater WP and higher grain yield under semiarid irrigation, and this combination may be introduced for sustainable rice production.

Effect of irrigation methods on root growth, root-shoot ratio and yield components of cotton by regulating the growth redundancy of root and shoot

Mulched drip irrigation is a common water-saving irrigation technology that can improve water resource utilization efficiency in arid areas. The change of irrigation method affects the growth of crop root system and then regulates the growth of aboveground organs. However, there have been limited comparative studies on how mulched drip irrigation affects the cotton root growth and regulates the relationship between cotton root and shoot. The objective of this study was to determine whether mulched drip irrigation could achieve water-saving and high-yield cotton cultivation by regulating the growth redundancy of root and shoot. Under field conditions, mulched drip irrigation (conventional drip irrigation and excessive drip irrigation) and traditional flood irrigation (conventional flood irrigation and reduced flood irrigation) were used in this experiment. Traditional flood irrigation was used as the control group. The results showed that compared with the traditional flood irrigation, the higher soil water content under mulched drip irrigation increased the specific root length (SRL), which promoted the growth of fine root length and biomass at the full flowering stage and prophase full boll stage. The growth of fine roots increased the root-shoot ratio (R/S) of mulched drip irrigation, and then inhibited the excessive vegetative growth of the aboveground parts. When entering the late full boll stage and boll opening stage, the fine root biomass and fine root mass fraction decreased rapidly under the mulched drip irrigation, resulting in a lower R/S. The smaller R/S of mulched drip irrigation facilitated the distribution of photosynthetic products to reproductive organs, which increased the boll number per plant by 7.30 %–25.10 %, thus increasing the boll loading of fine root system and seed cotton yield. However, compared with conventional drip irrigation, over irrigation led to excessive vegetative growth of cotton under excessive drip irrigation, which resulted in the decrease of boll opening rate and seed cotton yield by 8.71 %–17.19 % and 14.14 %–24.27 %, respectively. Moreover, the smaller R/S at the late growth stage enabled conventional drip irrigation to achieve the maximum water use efficiency (WUE). Therefore, mulched drip irrigation promoted the root growth of cotton and inhibited the vigorous vegetative growth of shoot before the prophase full boll stage, and then reduced the growth redundancy of root and increased the productive capacity of the fine root system after the prophase full boll stage, which increased boll number per plant and yield. However, only under the appropriate irrigation amount (390 mm), mulched drip irrigation can increase both yield and WUE, thus achieving the goal of water-saving and high-yield cultivation.

Agronomic Growth Performance of Super Rice under Water-Saving Irrigation Methods with Different Water-Controlled Thresholds in Different Growth Stages

Many water-saving techniques have been developed for rice production in response to irrigation water scarcity. The selection of the water-saving methods and the optimum thresholds for obtaining maximum benefits of these regimes are largely site-specific depending mainly on soil type, soil texture, and the environment. A two-year (2017 and 2018) experiment was conducted to evaluate the response of the agronomic growth performance, yield, and water use of super rice varieties under different irrigation regimes in Jiangsu Province, China. The irrigation regimes were comprised of different water-controlled thresholds, in different growth stages. Treatments included traditional flooding irrigation (FI, as the control) and the following four water-saving irrigation (WSI) regimes: shallow adjusting irrigation (WSI1), rainwater-catching and controlled irrigation (WSI2), controlled irrigation (WSI3), and drought planting with straw mulching (WSI4). The results showed that WSI treatments significantly increased the irrigation water use efficiency by 20.60% to 56.92% as compared with FI. The WSI treatments significantly decreased the crop evapotranspiration during the rice growth period. The grain yields of WSI1, WSI2, and WSI3 were significantly increased (6.62%~7.20% for WSI1, 8.21%~12.39% for WSI2, and 8.30%~12.91% for WSI3) as compared with that of the control, whereas WSI4 decreased the rice yield by 11.69%~18.10%. This research implies that WSI2 and WSI3 have the greatest potential for promotion in the lower reaches of the Yangtze River. An optimization of the irrigation threshold of WSI1 and WSI4 should be considered to guarantee the overall benefit.

Study on the Suitable Irrigation Amount of Microporous Membrane Water-Fertilizer Integration of Tomato in Spring in Plastic Greenhouse

Water-saving irrigation is an important measure to alleviate the shortage of water resources in China. In this study, the growth, nutrient distribution, quality and yield of Tomato under different irrigation treatments are studied by using microporous membrane water-fertilizer integrated technology and the optimal irrigation water quantity under the condition of microporous membrane water-fertilizer integration was determined. The results show that the stem diameter and the fresh and dry weight of tomato increased under the treatment of microporous membrane irrigation, among which the irrigation of 84 m3.667 m-2 was the best, comparing with the traditional flooding irrigation. Microporous membrane irrigation promotes the accumulation of N, P and K in tomato plants. The organic acid content of tomato fruit was the highest under the treatment of 108 m3.667 m-2 and the lycopene content is the highest under the treatment of 96 m3.667 m-2. However, soluble protein, soluble solids, VC content and sugar acid ratio are the highest under the treatment of 84 m3.667 m-2 and the yield and water use efficiency of tomato are the highest under this treatment. Generally, the optimal irrigation amount of tomato under the condition of microporous membrane water-fertilizer integration is 84 m3.667 m-2. The experiment clarifies the crop water demand characteristics and provides a certain theoretical basis for the application of water-saving irrigation technology and high-yield cultivation.

Effects of micro-sprinkling with different irrigation amount on grain yield and water use efficiency of winter wheat in the North China Plain

It’s very important to guarantee the wheat production and improve water productivity in the North China Plain (NCP). In order to reduce irrigation and ensure the crop production in the NCP, a two-year field experiment of winter wheat was conducted in 2016–2018 using micro-sprinkling irrigation including different irrigation amount treatments (60 mm, MI60; 90 mm, MI90; 120 mm, MI120; and 150 mm, MI150), and the local traditional water-saving and productive flooding irrigation method (TI120) was as a control. The grain yield (GY), dry matter accumulation (DM), root system distribution and water utilization were investigated. The results showed that, the GY of MI60 decreased by 5.1–13.4% compared with TI120; GY of MI90 was comparable with TI120, while that of MI120 and MI150 increased significantly. The higher GY in micro-sprinkling treatments was mainly due to the significant increase of 1,000-grain weight (TGW), which was the result of the significant delay of the senescence in flag leaves during grain filling and then the increase in the post-anthesis DM. In addition, the roots mainly distributed in the 0−60 cm soil profile, and micro-sprinkling ensured the soil water supply in this areas at the critical growth stages; what’s more, micro-sprinkling with reducing irrigation treatments significantly promoted the growth of root system to the deep soil layer, which improved the absorption and utilization of moisture stored in soil. Compared with TI120, the same irrigation amount treatment under micro-sprinkling (MI120) significantly increased water use efficiency (WUE) due to higher GY and lower seasonal evapotranspiration (ET); the 125% irrigation amount treatment (MI150) increased WUE due to higher GY and comparable ET; the 75% irrigation amount treatment (MI90) obtained the similar WUE to TI120; the 50% irrigation amount treatment (MI60) got similar or lower WUE to TI120. Overall, suitable reduction of irrigation amount under micro-sprinkling (MI90) can ensure the grain yield of winter wheat and efficient utilization of irrigation water in the NCP.

COMPARING TECHNICAL EFFICIENCY OF TRADITIONAL FLOODING AND DRIP IRRIGATION TECHNIQUES IN WATERMELON PRODUCTION IN TRA VINH PROVINCE

This article aims to compare the technical efficiency between two irrigation systems: traditional flooding and drip irrigation in watermelon production in Tra Vinh province, thereby recommending a more efficient farming model. This paper uses descriptive statistics, SFA and multivariable regression based on primary datacollected from 160 farmers applying these two irrigation models in Cau Ngang and Duyen Hai districts. The study found that the cost of plant variety, the amount of phosphorus, costs for post-harvesting, labor and irrigation affected the productivity of watermelon in the traditional flooding irrigation model; whereas the amount of potassium, the amount of phosphorus and cost of plant variety were factors affecting the productivity of watermelon in the drip irrigation model. Theresults also showed that producers applying the drip irrigation model achieved higher technical efficiency. The average efficiency levels achieved were 79,47% and 86,03% in the traditional flooding irrigation and drip irrigation respectively. In addition, the factors affecting the income of farmers in the traditional flooding irrigation model included household labor, loans, the amount of phosphorus, the amount of potassium, and cost of pesticides and irrigation. Meanwhile, the income of farmers in the drip irrigation model was affected by education, training, costs for post-harvesting and loans.

Response of Vertical Migration and Leaching of Nitrogen in Percolation Water of Paddy Fields under Water-Saving Irrigation and Straw Return Conditions

The use of water-saving irrigation techniques has been encouraged in rice fields in response to irrigation water scarcity. Straw return is an important means of straw reuse. However, the environmental impact of this technology, e.g., nitrogen leaching loss, must be further explored. A two-year (2017–2018) experiment was conducted to investigate the vertical migration and leaching of nitrogen in paddy fields under water-saving and straw return conditions. Treatments included traditional flood irrigation (FI) and two water-saving irrigation regimes: rain-catching and controlled irrigation (RC-CI) and drought planting with straw mulching (DP-SM). RC-CI and DP-SM both significantly decreased the irrigation input compared with FI. RC-CI increased the rice yield by 8.23%~12.26%, while DP-SM decreased it by 8.98%~15.24% compared with FI. NH4+-N was the main form of the nitrogen leaching loss in percolation water, occupying 49.06%~50.97% of TN leaching losses. The NH4+-N and TN concentration showed a decreasing trend from top to bottom in soil water of 0~54 cm depth, while the concentration of NO3−-N presented the opposite behavior. The TN and NH4+-N concentrations in percolation water of RC-CI during most of the rice growth stage were the highest among treatments in both years, and DP-SM showed a trend of decreasing TN and NH4+-N concentrations. The NO3−-N concentrations in percolation water showed a regular pattern of DP-SM &gt; RC-CI &gt; FI during most of the rice growth stage. RC-CI and DP-SM remarkably reduced the amount of N leaching losses compared to FI as a result of the significant decrease of percolation water volumes. The tillering and jointing-booting stages were the two critical periods of N leaching (accounted for 74.85%~86.26% of N leaching losses). Great promotion potential of RC-CI and DP-SM exists in the lower reaches of the Yangtze River, China, and DP-SM needs to be further optimized.

Drip irrigation and nitrogen management for improving crop yields, nitrogen use efficiency and water productivity of maize-wheat system on permanent beds in north-west India

The traditional flood irrigation system has led to overexploitation of ground water and low nitrogen (N) use efficiency. In north-western India, maize-based systems with lower irrigation requirement are being advocated as an alternate to rice-based systems to address the issues of declining water table. Bed planting of crops, straw mulching and drip irrigation are known to save precious irrigation water, and improve N use efficiency and grain yields. To this effect a two-year field experiment was conducted with annual wheat-maize rotation on permanent bed system to evaluate the effect of surface drip irrigation, residue management, and N application on crop and water productivity. Maize and wheat under drip irrigation with residue retention system showed significant grain yield increase of 13.7% and 23.1% compared to furrow irrigation with no residue, respectively. Surface drip irrigation with residue retention saved 88 mm and 168 mm of water and increased water productivity by 66% and 259% in wheat and maize on permanent beds compared to the conventional furrow irrigation system with residue removal, respectively. Similarly, fertigation at 10-day interval with five splits in wheat and seven splits in maize under drip irrigation system increased the mean N recovery efficiency by 16.5% and 29% compared to furrow irrigation in wheat and maize, respectively.

Optimized micro-sprinkling irrigation scheduling improves grain yield by increasing the uptake and utilization of water and nitrogen during grain filling in winter wheat

The North China Plain (NCP) is the main wheat production area in China; however, irrigation water and nitrogen fertilizer use in this area is relatively inefficient, and must be optimized to attain higher yield and resource use efficiency for winter wheat. In this study, a four-year field experiment was conducted during the 2012–2016 growing seasons. Under quota irrigation conditions, an experiment with various micro-sprinkling frequencies (S2, irrigation at jointing and anthesis; S3, irrigation at jointing, booting and filling; and S4, irrigation at jointing, booting, anthesis and filling) was conducted in 2012–2014. In 2014–2016, different nitrogen application rates (150, 195, and 240 kg N ha−1; denoted as S4N1, S4N2, and S4N3, respectively) under the S4 condition were tested. The local traditional flood irrigation pattern was designated as the control (CK) in 2012–2016. The grain yield, leaf area index of the population (LAI), flag leaf senescence during gain filling, accumulation and distribution of dry matter and nitrogen, and water and nitrogen use characteristics were investigated. The results showed that, no significant difference was observed in grain yield between the CK and S2, whereas S4 and S3 showed increased grain yields of 5.7–22.2% and 4.6–19.1%, respectively, compared with the CK. The increase of yield in micro-sprinkling treatments was mainly due to a significant increase in the 1000-grain weight. With increasing irrigation frequency, the LAI at the filling stage improved significantly; the flag leaf chlorophyll content decreased slowly; and the total dry matter accumulation, dry matter after anthesis, and its contribution to grain yield increased significantly. Meanwhile, the total water consumption of S4 (N2) decreased significantly, and the water use efficiency increased by 10.0–27.8% compared with the CK. In addition, micro-sprinkling irrigation with frequent application of a small amount of water with optimized nitrogen application (S4N2) yielded the highest nitrogen fertilizer use efficiency. Water consumption and nitrogen accumulation during grain filling were significantly increased in S4, which could explain the higher yield and resource use efficiency of S4. Overall, a suitable micro-sprinkling irrigation frequency (S4) and nitrogen application (195 kg N ha−1) can achieve higher grain yields and resource use efficiencies in the NCP.

Micro-irrigation improves grain yield and resource use efficiency by co-locating the roots and N-fertilizer distribution of winter wheat in the North China Plain

Water use efficiency (WUE) and nitrogen fertilizer use efficiency (NUE) of winter wheat are urgently needed to further improve in the North China Plain (NCP). In this study, a 3-year field experiment was conducted during the 2014–2017 growing seasons to clarify the effect of traditional flood irrigation (TI), surface drip irrigation (DI), and micro-sprinkling irrigation (MSI) on grain yield, WUE, and NUE of winter wheat. Across the 3 years, grain yield of DI and MSI improved by 9.79% and 14.1%, WUE of DI and MSI increased by 12.3% and 17.7%, and NUE of DI and MSI increased by 9.77% and 14.0%, respectively compared with those of TI. Wheat subjected to the micro-irrigation treatments (DI and MSI) had higher chlorophyll content in flag leaves 10 days post-anthesis; this postponed senescence of the flag leaves, which increased dry matter accumulation post-anthesis, and increased 1000-grain weight and grain yield. The micro-irrigation treatments reduced pre-anthesis water consumption but increased post-anthesis water consumption and ensured the water supply in the top soil layer at the critical stage, thus increasing WUE. Root length density (RLD) of TI in the 0–80-cm soil layer was significantly higher than that of micro-irrigation, whereas micro-irrigation had higher RLD than TI below the 80-cm soil layer, which promoted the absorption and utilization of water and nitrogen in deep soil. The micro-irrigation treatments increased total nitrogen accumulation of the plants, reduced soil nitrate nitrogen (NO3−-N) content at maturity, ensured the nitrogen supply in the top soil layer, thus increasing NUE. Overall, micro-irrigation with water and fertilizer as an integrated pattern significantly improved grain yield, WUE, and NUE of winter wheat in the NCP by co-locating the root, water, and N-fertilizer distribution and reducing NO3−-N accumulation in deep soil. The best treatment was micro-sprinkling irrigation.