Effect Of Water-saving Irrigation Research Articles

Direct-seeded rice reduces methane emissions by improving root physiological characteristics through affecting the water status of paddy fields

Both direct-seeded rice (DSR) and water-saving irrigation effectively reduce methane (CH4) emissions from paddy fields. However, little is known about the effects of water-saving irrigation with DSR on root growth and CH4 emissions in paddy fields. In this study, a field experiment was conducted with three treatments including transplanted flooded rice (TFR), direct-seeded flooded (DSF), and direct-seeded alternate wetting and drying (DSA), and root morphological and physiological traits and CH4 emissions were determined. Compared to TFR, DSR (DSF and DSA) significantly decreased CH4 emissions at all growth stages and reduced total CH4 emissions by 85.6–96.8%. Root morphological traits were significantly and positively correlated with total CH4 emissions, whereas root oxidation activity (ROA); root oxygen loss (ROL); and root organic acids malic acid (MA), succinic acid (SA) and citric acid (CA) were significantly and negatively correlated with total CH4 emissions. The flooding depth (FD), flooding period (FP), and total water input (TWI) were 34.1%, 17.8%, and 22.1% lower for DSF and 79.5%, 88.2%, and 53.7% lower for DSA, respectively, compared with those of TFR, which showed a significant positive correlation with CH4 emissions. These results suggest that DSF and DSA improve the root physiological traits of rice by regulating the water status of paddy fields, which in turn lead to CH4 reduction. The results of this study are essential for developing sustainable management practices for paddy soils and reducing greenhouse gas emissions.

Effects of Water-Saving Irrigation on Direct-Seeding Rice Yield and Greenhouse Gas Emissions in North China

Rice cultivation consumes more than half of the planet’s 70% freshwater supply used in agricultural production. Competing water uses and climate change globally are putting more pressure on the limited water resources. Therefore, water-saving irrigation (WSI) is recommended for rice production in water scares areas. The impact of WSI techniques on direct-seeding rice production and greenhouse gas emissions in North China is becoming increasingly important in the era of climate change. Therefore, we conducted a two-year field experiment on directly seeded rice to assess the impact of traditional flooding irrigation (CK) and three water saving irrigation (WSI) methods, including drip irrigation with an irrigation amount of 50 mm (DI1) and 35 mm (DI2) at each watering time and furrow wetting irrigation (FWI), on rice yield and greenhouse emissions. Generally, the WSI techniques decreased the number of rice panicles per m−2, spikelet per panicle, 1000-grain weight and rice yield compared to CK. Rice yield and yield components of (DI1) were significantly higher than (DI2). The adoption of either (DI1) or (FWI) showed insignificant variation in terms of rice yield and its yield components measured except for 1000-grain weight. The water productivity was 88.9, 16.4 and 11.4% higher in the FWI plot than the CK, DI1 and DI2 plots, respectively. The WSI decreased cumulative CH4 emission significantly by 73.0, 84.7 and 64.4% in DI1, DI2 and FWI, respectively, in comparison with CK. The usage of DI2 triggered 1.4 and 2.0-fold more cumulative N2O emission compared to DI1 and FWI, respectively. Area-scaled emission among the water-saving irrigation methods showed no significance. The yield-scaled emission in DI1 and DI2 and FWI were 101, 67.5 and 102%, respectively, significantly lower than CK. The adoption of FWI produced an acceptable rice yield with the lowest yield-scaled emission and highest water productivity among the irrigation practices. Our experiment demonstrates that dry direct-seeding with furrow irrigation can impact triple-wins of sustainable rice yield, high water-use efficiency and low GHG emissions in North China.

The effect of water-saving irrigation on the growth of local rice plants

The decline in the function of the watershed causes the increasing scarcity of water, while the competition for water use is increasing. A conventional method of rice cultivation (continuous inundation) is very wasteful in the use of irrigation water. Water-saving irrigation by regulating the water availability in rice fields is an effort to reduce water loss due to percolation, seepage, and runoff. The study’s purpose was to examine the effect of water availability in the field on the growth of local rice varieties. The study used 5 treatments of water availability in the field (GW < 50% AW, 50% AW < GW ≥ 60% AW, 60% AW< GW ≥ 70% AW, 70% AW < GW ≥ 80% AW, and saturated) with 3 replicates and the parameters observed were the height of plants and number of tillers. The results showed that the availability of water in the field did not affect the plant height but did affect the number of tillers. From the vegetative phase at the age of ±28 days after planting (DAP) to the beginning of the generative phase ±55 DAP, there was an addition of tillers. When the generative phase period from ± 55 DAP, the formation of the tillers stopped, and some of the tillers dried up or died.

Effect of water-saving irrigation on the N2O dynamics and the contribution of exogenous and endogenous nitrogen to N2O production in paddy soil using 15N tracing

Water-saving irrigation techniques can effectively mitigate methane emissions from rice fields but typically enhance nitrous oxide (N2O) emissions due to changes in soil moisture content. However, few studies have examined the effect of different water regimes on N2O production using different species of exogenous nitrogen (N) fertilizer application. Furthermore, the contributions of exogenous N fertilizer and endogenous N of soil for N2O productions have not been elucidated. Using a series of lysimeters, three types of water management were employed in rice cultivation in this study: conventional irrigation management (CIM), alternate wetting and drying (AWD), and dry cultivation management (DCM). Ammonium nitrate (NH4NO3) fertilizer was applied as base, tillering, and heading fertilizer, which was then separated into two groups labeled with 15N stable isotope (> 99 %) at two different N positions: 15NH4NO3 and NH415NO3.Higher peaks of N2O flux were observed following drainage of floodwater for AWD and DCM treatments. In addition, 15N2O fluxes were clearly separated into two different patterns between 15NO3– and 15NH4+ fertilizer application. Application of 15NO3− fertilizer rapidly released 15N2O but the 15N2O flux for 15NH4+ fertilizer application slowly increased with a hysteresis effect, suggesting denitrification was the main pathway for 15N2O production in paddy soil with 15NO3− fertilizer added in a flooded situation. Conversely, 15NH4+ may need to be converted into 15NO3– through nitrification, then denitrified and finally released as 15N2O. Furthermore, N2O production was likely enhanced by nitrification–denitrification processes due to the water level alternating near the ground surface for AWD treatment. Consequently, the total N2O emission over the rice growing period was the highest from the AWD soils, at 2.4 times that for CIM treatments. The high proportion of N2O-N derived from soil endogenous N sources (81 % of total N2O emission) in the AWD treatment indicates that the alternating wetting–drying of soil stimulated N2O production using endogenous N mineralized from soil organic matter. Furthermore, water management of paddy soil affected N uptake by rice plants. The total N uptake by rice plants was significantly higher for CIM than for AWD and DCM treatments.

Does water-saving irrigation improve the quality of fruits and vegetables? Evidence from meta-analysis

Water productivity has become a key requirement in sustainable crop production and environmental management. Deficit irrigation (DI) and partial root-zone drying irrigation (PRDI) are two strategies that have been exploited to maximize crop production per unit water, with attendant effect on the quality attributes of harvest index. We employed meta-analysis to synthesize evidence for the relative performance of full irrigation (FI), DI and PRDI for three quality attributes of fruits and vegetables, namely, total soluble solids (TSS), titratable acidity (TA) and pH. Overall, TSS, TA and pH of crops under DI and PRDI do not differ significantly. However, TSS in crops under DI and PRDI are significantly larger than that of crops under FI. DI and PRDI improve TSS by 4.1 ± 1.8% and 5.0 ± 2.0%, respectively, relative to FI. Crops under the three irrigation techniques do not differ significantly in TA and pH. The differences in TSS of crops are contextual, depending on type of crop, soil texture and irrigation frequency. The effect of water-saving irrigation on the selected crop quality attributes may, therefore, have the add-on effects of crop, system and/or site characteristics. Therefore, in terms of quality attributes, water-saving irrigation techniques are superior to FI when considering improvement in TSS without significantly altering TA or pH of fruits and vegetables.

Effects of water-saving irrigation on the residues and risk of polycyclic aromatic hydrocarbon in paddy field

The effects of different water-saving modes on PAHs residue and risk, field environment conditions and enzyme activities in paddy field were investigated in a field experiment plot in Laoyaba, Nanjing, China. Results showed that (1) water-saving treatment affected greatly the ΣPAHs in water and soil. The order of ΣPAHs residue in surface water and groundwater in farmland is as follows: dry fields<water-saving paddy field<flooding irrigation paddy field. The ΣPAHs in water during rice tillering stage were obviously higher than that in rice booting stage and milky stage, and the percentage of high-ring PAHs gradually reduced in water. (2) The residue of ΣPAHs in soil in flooding irrigation paddy field (534.4±186.7ng/g) were more than water-saving irrigation (454.3±128.1ng/g) and dry cultivation paddy field (430.2±143.4ng/g), and the ΣPAHs in dry field gradually decreased with the increase of water furrow number in farm. (3) When compared with flooding irrigation (337.87ng/g), water-saving (228.39ng/g) and dry cultivation (206.62ng/g) could obviously decrease the residue of ΣPAHs in rice tissues (35%–55%), generally the concentration of ΣPAHs in leaf>root>stem>rice grain. (4) Water-saving irrigation evidently decreased soil ecological risk (up to 55%–73%) and rice carcinogenic risk (up to 30%–45%) caused by PAHs compared with flooding irrigation. Water-saving irrigation could also reduce the Total Toxic Equivalency Concentration of PAHs in rice grain up to 50% relative to flooding irrigation. (5) The significant negative correlations were observed between the residual PAHs and the activities of laccase and dioxygenase (p<0.019), and the physical and chemical indexes (temperature, redox potential and dissolved oxygen of field, p<0.041). The changes of field environment conditions and enzyme activities induced by moisture control may be the main key factors affecting PAHs residue in water, soil and rice.

Effects of Water-Saving Irrigation on Emissions of Greenhouse Gases and Prokaryotic Communities in Rice Paddy Soil

The effects of water-saving irrigation on emissions of greenhouse gases and soil prokaryotic communities were investigated in an experimental rice field. The water layer was kept at 1-2 cm in the water-saving (WS) irrigation treatment and at 6 cm in the continuous flooding (CF) irrigation treatment. WS irrigation decreased CH(4) emissions by 78 % and increased N(2)O emissions by 533 %, resulting in 78 % reduction of global warming potential compared to the CF irrigation. WS irrigation did not affect the abundance or phylogenetic distribution of bacterial/archaeal 16S rRNA genes and the abundance of bacterial/archaeal 16S rRNAs. The transcript abundance of CH(4) emission-related genes generally followed CH(4) emission patterns, but the difference in abundance between mcrA transcripts and amoA/pmoA transcripts best described the differences in CH(4) emissions between the two irrigation practices. WS irrigation increased the relative abundance of 16S rRNAs and functional gene transcripts associated with Anaeromyxobacter and Methylocystis spp., suggesting that their activities might be important in emissions of the greenhouse gases. The N(2)O emission patterns were not reflected in the abundance of N(2)O emission-related genes and transcripts. We showed that the alternative irrigation practice was effective for mitigating greenhouse gas emissions from rice fields and that it did not affect the overall size and structure of the soil prokaryotic community but did affect the activity of some groups.

Effects of Water Management Methods on CH4and N2O Emission From Rice Paddy Field

The effects of water-saving irrigation on the emissions of greenhouse gases and the prokaryotic communities in rice paddy soils were investigated through a field experiment. In the Water-Saving (WS) irrigation, the water layer was kept at 2~3 cm while it was kept at 6 cm in the Continuousiy Flooding (CF) irrigation. A plot was treated with Intermittently Drainage (ID) that is drained as fine cracks on the floor were seen after transplanting. GHGs emission amounts from WS plots were reduced by 78.1% compared to that from CF plot and by 70.7% compared to that from ID plot, meaning that WS could help contribute to mitigation of the greenhouse gas accumulation in the atmosphere.

Study on Plant Water Stress Based on Ultrasonic Acoustic Emissions

The soil water deficit and strong transpiration can give rise to the phenomenon of plant water stress. Because of the water stress produces the fracture of the water column in conduits, and the fracture is the reflection of energy release which can be detected by the ultrasonic acoustic emissions (UAEs) technology. In order to avoid background noise interference, the UAEs detecting frequency is between 100K Hz and 1 MHz. The PCI-2 data acquisition (DAQ) card and R15 sensors are used to improve the precision of UAEs detection. When the water stress and dehydration gets heavier, the UAEs get higher. Use the tomato plant data with the empirical deduction under the modern greenhouse conditions, the relationships among UAEs, transpiration and UAEs signal strength is described by curve. The UAEs signals occur generally from 5:00~7:00 am, and stop after 20:00 at night. In the daytime, when the plant body water storage is few, and transpiration is strong, the UAEs occur two peaks, called the “Twin Peaks Area” (TPA). In the different conditions of soil water content status and environmental factors, the TPA occur time will be advance or lag, which is generally in the range of 8:00~15:00. An acoustic emission event maybe produces several UAEs counts, while the UAEs counts have a correspondence with the UAEs signal strength. It is better to use UAEs technique to diagnose the plant water status and carry out automatic and precise irrigation for the plant and to improve the effect of Water-saving irrigation.

Study on Irrigation Model Based on Plant Ultrasonic Acoustic Emissions

Produced by cohesion between water molecules or adhesion to the conduit wall, the plant cavitation is accompanied by the vessel walls vibration which is the indicator of the water stress. The ultrasonic acoustic emissions (UAEs) are used to detect the plant cavitation events which are the transmission of vibration. The UAEs could be detected in ultrasonic frequencies between 100K Hz and 1 MHz. The PCI-2 data acquisition (DAQ) equipment and R15 sensors are used to improve the precision of cavitation detection. When the water stress and dehydration gets heavier, the UAEs rate gets higher. Use the tomato practice data with the empirical deduction under the modern greenhouse conditions, the UAEs and Transpiration Index (UAETI) and the UAEs Irrigation Index (UAEII) irrigation model are draw from the relationship between transpiration and UAEs. UAETI can be used to analysis the transpiration, and UAEII can be used to analysis the irrigation time. It is better to use UAEs technique to carry out automatic and precise irrigation for the plant and to improve the effect of Water-saving irrigation.

Effects of water-saving irrigation and groundwater depth on direct seeding rice growth, yield, and water use in a semi-arid region

In Iran, rice is grown in areas where the groundwater depth (GD) is low. Therefore, water-saving irrigation (WSI) can be used instead of continuous flood irrigation (CFI) in order to use the groundwater. The objectives of this study were to investigate the interaction effects of irrigation regimes and GDs on growth and yield of rice and groundwater contribution (GC) to crop evapotranspiration (ET) in cylindrical greenhouse lysimeters. Irrigation regimes were CFI and intermittent flood irrigation (IFI) with 4- and 8-day intervals (IFI-4 and IFI-8, respectively), and GDs were 0.3, 0.45, and 0.60 m. Results indicated that in a climate condition similar to experimental environment in greenhouse, using IFI-4 at a GD of 0.3 m produced grain yield and straw and root dry matter (DM) similar to those obtained when using CFI, with 53% reduction in irrigation water use. However, straw and root DM increased in CFI with increasing soil column length. Maximum GC/ET (41%) was observed when using IFI-4 at a GD of 0.3 m. A multiple regression equation was presented to estimate GC/ET as a function of GD and soil moisture deficit (SMD). This equation indicates that at a given GD with extension of irrigation intervals and increased SMD GC/ET reached a maximum value followed by a decrease afterwards. Maximum values of GC/ET were obtained at SMD values of 0.47, 0.40, and 0.33 at GDs of 0.3, 0.45, and 0.6 m, respectively.

Lasting effects of controlled irrigation during rice-growing season on nitrous oxide emissions from winter wheat croplands in Southeast China

Nitrous oxide (N2O) emission from croplands in China is a serious environmental concern. Water management is an important factor in regulating N2O emissions from croplands. In China, controlled irrigation (CI) is one mode of the water-saving irrigation for rice and is widely used. This study aims to assess the lasting effects of CI on N2O emissions from winter wheat croplands in Southeast China, with traditional irrigation (TI) as the control. CI performed during the rice-growing season had obvious lasting effects on N2O emissions of the subsequent winter wheat-growing season. Compared with TI, CI significantly increased the cumulative N2O emission by 129.1 % during the rice-growing season (p 0.05). The results suggest that CI does not significantly increase the cumulative N2O emission from the rice–winter wheat rotation systems while insuring rice and wheat yields. This study focuses on the lasting effects of water-saving irrigation mode during rice-growing season on N2O emissions during the following wheat-growing season. Thus, it is a development and complement of the previous researches on the effects of water-saving irrigation on N2O emissions from rice–winter wheat rotation croplands.

The Effect of Water Saving Irrigation and Nitrogen Fertilizer on Rice Production in Paddy Fields of Iran

Rice production in Iran needs to increase to feed a growing population whereas water for irrigation is getting scarce. There are 230000 ha paddy fields in Guilan province in north of Iran. About 73% of paddy fields irrigated by Sepeedrood dam. Shortage of water for rice production will be a problem in near future. In order to investigate the best irrigation regime and nitrogen level an experiment was conducted in split plot based on completely randomized block design with 3 replications at the rice research institute of Iran in 2008. Four levels of nitrogen (N1= 0, N2 = 90, N3 = 120 and N4 = 150 kg ha-1) w ere splited on 4 different irrigation managements (I1= con tinuous submergence (CS), I2 = 5, I3 = 8 and I4 = 11 days interval). The results clearly indicate that nitrogen levels and irrigation management in most of studied characteristics had very significant differences. Not only grain yield was statistically the same under CS and 8 days interval but also water consumption decreased 18%. Thus, concluded that water limited irrigation can lead to reduce water consumption in paddy fields and minimum 150 million m3 water of Sepeedrood dam saved annually.

Effect of Water-Saving Irrigation on CH&lt;sub&gt;4&lt;/sub&gt; Emissions from Rice Fields

Although water saving irrigation (WSI) has been widely used in China, there is limited understanding on the effect of such a practice on the CH4 emission in rice fields. Consequently it is difficult to estimate the regionSubscript textal distribution of CH4 emissions in space and time from rice fields across China. Two water treatments (controlled irrigation (CI), a routine WSI practice in China, and a traditional continuous flooded irrigation (FI)) were used to examine diurnal and seasonal variations of CH4 emissions in field experiments in Kunshan, east China. The heavy loams in the site have organic matter content of 30.3 g/kg while percolation rates in the shallow groundwater range from 2 to 10 mm per day. Gas samples were collected and analyzed using a static chamber technique and a Gas Chromatograph system respectively. The results show that under WSI conditions, the diurnal variation of CH4 emissions presented regular afternoon-maximum mode during the initial and middle tillering stage, which mainly depends on air temperature. Only one peak of CH4 emission occurred in initial/middle tillering growth stage of rice season under CI conditions, which is mainly regulated by drainage or water layer receding. For CI, seasonal CH4 emission is 2.4 g•m-2~24.5g•m-2, and the seasonal average flux is 0.8 mg•m-2•h-1~8.15 mg•m-2•h-1, which is 39-85% lower than that for FI. CI has more mitigation potential than midseason drainage. Furthermore, CI significantly reduces irrigation water use while maintains rice yields, even increases yields under atrocious weather conditions. A hydrologic characterization and spatial distribution of rice field in China is needed to assess the extent and magnitude of potential emission reduction in the region.

Effects of Water-Saving Irrigation and Nitrogen Fertilization on Yield and Yield Components of Rice (Oryza sativa L.)

The effects of nitrogen (N) application (32, 72 and 112 kg N ha-1 in 2000, and 32, 92 and 152 kg N ha-1 in 2001) and water-saving irrigation and their interaction on grain yield and yield components of the rice cultivar Champa-Kamphiroozi, which is a local cultivar in a semi-arid area in the south of Islamic Republic (I.R.) of Iran, were investigated. The plants were cultivated under sprinkler irrigation (1.0 ETp and 1.5 ETp), intermittent flooding (1-day and 2-day intervals) and continuous flooding (control). The experiments were conducted on a clay loam-clay soil under a semi-arid environment using four replications in a split plot design with irrigation method as main plots and N levels as subplots. The results indicated that intermittent flooding irrigation at 2-day intervals was as effective as continuous flooding for grain yield, showing high water-use efficiency (WUE). The soil moisture tension in the root zone before each irrigation under this condition was –300 to –400 cm. Sprinkler irrigation and intermittent flooding increased WUE by 20 to 60%, compared with continuous flooding, and the increase in N application rate to 112-152 kg ha-1 increased grain yield under any irrigation condition. Under sprinkler irrigation, grain yield was low and percentage of unfilled grain was high, although WUE was high. However, by adopting sprinkler irrigation, the amount of nitrogen fertilizer application necessary for cultivation was reduced. Furthermore, when nitrogen application must be limited due to groundwater pollution, the amount of nitrogen fertilizer necessary for cultivation can be reduced.

Effect of water-saving irrigation on rice yield and water use in typical lowland conditions in Asia

With decreasing water availability for agriculture and increasing demand for rice, water use in rice production systems has to be reduced and water productivity increased. Alternately submerged–nonsubmerged (ASNS) systems save water compared with continuous submergence (CS). However, the reported effect on yield varies widely and detailed characterizations of the hydrological conditions of ASNS experiments are often lacking so that generalizations are difficult to make. We compared the effects of ASNS and CS on crop performance and water use, at different levels of N input, in field experiments in China and the Philippines, while recording in detail the hydrological dynamics during the experiment. The experiments were conducted in irrigated lowlands and followed ASNS practices as recommended to farmers in China. The sites had silty clay loam soils, shallow groundwater tables and percolation rates of 1–4.5 mm per day. Grain yields were 4.1–5.0 t ha −1 with 0 kg N ha −1 and 6.8–9.2 t ha −1 with 180 kg N ha −1. Biomass and yield did not significantly differ between ASNS and CS, but water productivity was significantly higher under ASNS than under CS in two out of three experiments. There was no significant water×N interaction on yield, biomass, and water productivity. Combined rainfall plus irrigation water inputs were 600–960 mm under CS, and 6–14% lower under ASNS. Irrigation water input was 15–18% lower under ASNS than under CS, but only significantly so in one experiment. Under ASNS, the soils had no ponded water for 40–60% of the total time of crop growth. During the nonsubmerged periods, ponded water depths or shallow groundwater tables never went deeper than −35 cm and remained most of the time within the rooted depth of the soil. Soil water potentials did not drop below −10 kPa. We argue that our results are typical for poorly-drained irrigated lowlands in Asia, and that ASNS can reduce water use up to 15% without affecting yield when the shallow groundwater stays within about 0–30 cm. A hydrological characterization and mapping of Asia’s rice area is needed to assess the extent and magnitude of potential water savings.