Search Results (18)

This study investigated the effects of different water management practices on the growth, yield, and grain quality of rice grown under environmentally friendly farming methods in Apgok-Ri, Gungnyu-Myeon, Uiryeong-Gun, from 2022 to 2024. Treatments included mid-season drainage for 2, 3, or 4 weeks (2MD, 3MD, 4MD), followed by either low-level water management (MD-1) or alternate wetting and drying (MD-2), with continuous flooding (CF) as the control. The rice variety was machine-transplanted on 9–10 June, and organic fertilizer (90 kg N/ha) was applied as a basal dressing. Water treatments were initiated in mid-July each year. The highest yield was consistently recorded in the 2MD-2 treatment, with 5.85, 5.74, and 5.38 tons/ha from 2022 to 2024, representing 15.0%, 14.5%, and 7.8% increases over CF, respectively. On average, alternate irrigation (MD-2) resulted in higher yields than low-level water management (MD-1) by 1.19–5.90%. Grain quality was also highest in 2MD-2, showing the greatest percentage of ripened grains each year, whereas CF had the highest proportion of immature and unripe grains. Crude protein content in brown rice was lowest in 3MD-2 (6.12%), followed by 2MD-2 (7.51%). Incidences of major diseases such as sheath blight, rice blast, panicle blight, and bacterial grain blight were highest in the CF treatment. Rice leaf blight was not significantly different in 2022, but was most prevalent in CF in 2023 and 2024. There were no major differences in brown planthopper and false smut incidence, although false smut peaked in CF in 2024. These findings suggest that 2-week mid-season drainage followed by alternate irrigation (2MD-2) is an effective strategy to improve yield, grain quality, and disease resistance in sustainable rice farming systems. Full article

This study evaluated the growth characteristics and yield of rice under various water management strategies in an environmentally friendly paddy field in Korea from 2022 to 2024. The water management treatments included mid-season drainage (MD) lasting for 2, 3, or 4 weeks, followed by either low-level water management (maintaining a 4 cm water depth, denoted as “1”) or alternate wetting and drying irrigation (4 cm irrigation followed by drying, denoted as “2”) until harvest. The conventional treatment consisted of continuous flooding (CF). Treatments with poor yields (4MD1 and 4MD2) were discontinued in subsequent years. The rice cultivar Saecheongmu was transplanted in June, and water management began in July. Among the treatments, CF produced the highest number of mean panicles, whereas the 2MD2 treatment showed the most favorable yield components. The highest mean grain yield was recorded in 2MD2, with values of 5.85, 5.74-, and 5.38-tons ha⁻¹ over the three years—representing a 7.8–15.0% increase compared to CF. Across all treatments, MD1 consistently produced higher yields than MD2. Water use was lowest in 2MD2, achieving a 61.8% reduction compared to CF. Overall, the 2MD2 treatment emerged as the most promising strategy, effectively reducing water use by 61.8% while maintaining high yields comparable to those under continuous flooding. Full article

The rice-wheat rotation system is a major agricultural practice in China as well as an important source of greenhouse gas (GHG) emissions. In this study, the developed mid-infrared laser heterodyne radiometer (MIR-LHR) was used for the remote sensing of atmospheric CH₄ and N₂O concentrations above the rice-wheat rotation system. From April 2019 to May 2022, the atmospheric column concentrations of CH₄ and N₂O above the rice-wheat rotation system were continuously observed in Hefei, China. The peak values of the N₂O column concentration appeared 7~10 days after wheat seasonal fertilization, with additional peaks during the drainage period of rice cultivation. During the three-year rice-wheat crop rotation cycle, a consistent trend was observed in the CH₄ column concentrations, which increased during the rice-growing season and subsequently decreased during the wheat-growing season. The data reveal different seasonal patterns and the impact of agricultural activities on their emissions. During the observation period, the fluctuations in the CH₄ and N₂O column concentrations associated with the rice-wheat rotation system were about 40 ppbv and 6 ppbv, respectively. The MIR-LHR developed for this study shows great potential for analyzing fluctuations in atmospheric column concentrations caused by GHG emissions in the rice-wheat rotation system. Full article

The WINDS (Water-Use, Irrigation, Nitrogen, Drainage, and Salinity) model uses the FAO56 dual crop coefficient and a daily time-step soil–water balance to simulate evapotranspiration and water content in the soil profile. This research calibrated the WINDS model for simulation of guayule under full irrigation. Using data from a furrow irrigated two-season guayule experiment in Arizona, this research developed segmented curves for guayule basal crop coefficient, canopy cover, crop height and root growth. The two-season guayule basal crop coefficient (K_cb) curve included first and second season development, midseason, late-season and end-season growth stages. For a fully irrigated guayule crop, the year one midseason K_cb was 1.14. The second year K_cb development phase began after the crop was semi-dormant during the first winter. The second year K_cb value was 1.23. The two-season root growth curve included a growth phase during the first season, no growth during winter, and a second growth phase during the second winter. A table allocated fractions of total transpiration to soil layers as a function of root depth. With the calibrated tables and curves, the WINDS model simulated soil moisture content with a root mean squared error (RMSE) of 1- to 3-% volumetric water content in seven soil layers compared with neutron probe water contents during the two-year growth cycle. Thus, this research developed growth curves and accurately simulated evapotranspiration and water content for a two-season guayule crop. Full article

The occurrence of extreme warm events in the Arctic has been increasing in recent years in terms of their frequency and intensity. The assessment of the impact of these episodes on the snow season requires further observation capabilities, where spatial and temporal resolutions are key constraints. This study targeted the snow season of 2022 when a winter rain-on-snow event occurred at Ny-Ålesund in mid-March. The selected methodology was based on a multi-scale and multi-platform approach, combining ground-based observations with satellite remote sensing. The ground-based observation portfolio included meteorological measurements, nivological information, and the optical description of the surface in terms of spectral reflectance and snow-cover extent. The satellite data were obtained by the Sentinel-2 platforms, which provided ten multi-spectral acquisitions from March to July. The proposed strategy supported the impact assessment of heat waves in a periglacial environment, describing the relation and the timing between rain-on-snow events and the surface water drainage system. The integration between a wide range of spectral, time, and spatial resolutions enhanced the capacity to monitor the evolution of the surface water drainage system, detecting two water discharge pulsations, different in terms of duration and effects. This preliminary study aims to improve the description of the snow dynamics during those extreme events and to assess the impact of the produced break during the snow accumulation period. Full article

Mid−season drainage (MSD) is a widely used water management practice in rice (Oryza sativa L.) cultivation. However, the timing of the initiation and termination of MSD is highly arbitrary and subjective, and a quantitative indicator is lacking in precision agronomic practice. In this study, datasets (91 cases) from previous field experiments were obtained and used to fit adjusted exponential growth models, incorporating rice canopy light interception (CLI) and tillering development dynamics. Different criteria for initiating and terminating MSD were developed based on CLI indicators. The results showed that the CLI indicator at 80% of the projected panicle could be used to predict the initiation of MSD; however, it was highly variable, depending on the growing season and rice cultivated variety. The values for Indica rice were 0.26 to 0.31 and 0.31 to 0.42 in the late and single seasons, respectively, while the values for Japonica rice were 0.15 to 0.29 and 0.23 to 0.33, respectively. In addition, the CLI values at 7 to 10 days prior to panicle initiation (PI) ranged from 0.77 to 0.87 and from 0.56 to 0.83 for the Indica and Japonica varieties, respectively, and were calculated to determine MSD termination. The CLI indicators for MSD were greatly dependent on the cultivated variety, growing season, and planting method. The results of the correlation study and principal component analysis (PCA) indicated that the differences in CLI values attributed to rice type and growing season were driven by the tillering and canopy characteristic traits, respectively. Therefore, the current parameters could provide a reference for subsequent field applications in specific areas, but further optimization is needed to increase their robustness. To evaluate the usefulness of the CLI indicator for determining MSD initiation and termination, a set of devices for monitoring canopy light interception and water level was developed, and an on-farm trial was carried out in the middle and lower reaches of the Yangtze River in China in 2022. The field application demonstrated that MSD could be scheduled automatically based on the current system, and that the effect was consistent in practice. Full article

The increase in the frequency and intensity of hazardous hydrometeorological phenomena is one of the most dangerous consequences of climate instability. In this study, we summarize the data on severe weather phenomena using the data from 23 meteorological stations in Crimea from 1976 to 2020. Particular attention was paid to the precipitation phenomena descriptions. For the last 45 years, a significant positive trend of interannual variability of the annual occurrence of severe weather phenomena was estimated to be +2.7 cases per decade. The trend for severe precipitation phenomena was estimated to be +1.3 cases per decade. The probable maximum annual daily precipitation as a quantitative indicator of hazardous events was estimated for each station by using both the stationary and the non-stationary GEV models. For at least half of the meteorological stations, a non-stationary GEV model was more appropriate for the estimation of the precipitation extremes. An analysis of the main synoptic processes that drive severe weather phenomena of precipitation was carried out. The greatest contribution to the formation of severe precipitation was made by Mediterranean–Black Sea cyclones. At the same time, half of all of the cases of extreme precipitation were caused by cyclones generated over the Black Sea only, in all seasons apart from winter. In the mid-troposphere, four types of meridional circulation were identified depending on the location of troughs and ridges, with respect to the Black Sea region. More than 42% of severe precipitation phenomena were accompanied by an isolated high-altitude cyclone in the mid-troposphere over the Black Sea region. The main recommendation that can be drawn from this study is that long-term climatic non-stationarity should be taken into account whenever the risk assessment or hazard analysis is to be carried out. The results can also favor the designing of drainage and sewerage systems in urban areas. The findings of atmospheric patterns can be used for the improvement of extreme precipitation forecasts. Full article

Rice is an important economic crop in Thailand. However, paddy rice fields are one of the largest anthropogenic sources of methane (CH₄) emissions. Therefore, suitable crop management practice is necessary to reduce CH₄ emissions while rice grain yield is maintained. This study aimed to evaluate appropriate options of fertilizer and water management practices for Thai rice cultivation with regards to improving rice grain yield and reducing CH₄ emissions. The Denitrification–Decomposition (DNDC) model was used to simulate grain yield and the emission of CH₄ under the three fertilizer options (chemical fertilizer (F), manure (M) and chemical fertilizer + manure (F + M)) with three water management options (continuous flooding (CF), mid-season drainage (MD) and alternate wet and dry (AWD)) during the years 2011–2050. Rain-fed and irrigated rice cropping systems were used. A total of 24 sites distributed in 22 provinces were studied. The data sets of daily climate, soil properties, and rice management practices were required as inputs in the model. Model validation with observation data in a field experiment indicated that simulated grain yields (R² = 0.83, slope = 0.98, NRMES = 0.30) and cumulative seasonal CH₄ emissions (R² = 0.83, slope = 0.74, NRMES = 0.43) were significantly and positively correlated with the observation. At the end of the simulation period (2046–2050), fertilizer management options of F and F + M gave more grain yield than the M management option by 1–44% in rain-fed rice cropping and 104–190% in irrigated rice cropping system, respectively. Among options, the lower CH₄ emissions were found in AWD water management options. The appropriate options with regard to maintaining grain yield and reducing CH₄ emissions in the long term were suggested to be F + M with AWD for the rain-fed rice, and F with AWD for the irrigated rice cropping systems. Full article

Although rice paddy fields are one of the world’s largest anthropogenic sources of methane CH₄, the budget of ecosystem CH₄ and its’ controls in rice paddies remain unclear. Here, we analyze seasonal dynamics of direct ecosystem-scale measurements of CH₄ flux in a rice-wheat rotation agroecosystem over 3 consecutive years. Results showed that the averaged CO₂ uptakes and CH₄ emissions in rice seasons were 2.2 and 20.9 folds of the wheat seasons, respectively. In sum, the wheat-rice rotation agroecosystem acted as a large net C sink (averaged 460.79 g C m⁻²) and a GHG (averaged 174.38 g CO₂eq m⁻²) source except for a GHG sink in one year (2016) with a very high rice seeding density. While the linear correlation between daily CH₄ fluxes and gross ecosystem productivity (GEP) was not significant for the whole rice season, daily CH₄ fluxes were significantly correlated to daily GEP both before (R²: 0.52–0.83) and after the mid-season drainage (R²: 0.71–0.79). Furthermore, the F partial test showed that GEP was much greater than that of any other variable including soil temperature for the rice season in each year. Meanwhile, the parameters of the best-fit functions between daily CH₄ fluxes and GEP shifted between rice growth stages. This study highlights that GEP is a good predictor of daily CH₄ fluxes in rice paddies. Full article

Cover crop management during the fallow season may play a relevant role in improving crop productivity and soil quality, by increasing nitrogen (N) and soil organic carbon (SOC) accumulation, but has the possibility of increasing greenhouse gas (GHG) emissions from the soil. A year-long consistency experiment was conducted to examine the effects of various winter covering crops on annual nitrous oxide (N₂O) together with methane (CH₄) emissions in the mono-rice planting system, including direct emissions in the cover crop period and the effects of incorporating these crops on gaseous emissions during the forthcoming rice (Oryza Sativa L.) growing period, to improve the development of winter fallow paddy field with covering crops and to assess rice cultivation patterns. The experiment included three treatments: Chinese milk vetch-rice (Astragalus sinicus L.) with cover crop residue returned (T1), ryegrass (Lolium multiflorum L.)-rice with cover crop residue returned (T2), and rice with winter fallow (CK). Compared with CK, the two winter cover crop treatments significantly increased rice yield, soil organic carbon (SOC) and total nitrogen (TN) by 6.9–14.5%, 0.8–2.1% and 3.4–5.4%, respectively. In all cases, the fluxes of CH₄ and N₂O could increase with the incorporation of N fertilizer application and cover crop residues. Short-term peaks of these two gas fluxes were monitored after all crop residues were incorporated in the soil preparation period, the early vegetative growth period and the midseason drainage period. The winter cover crop residue application greatly enhanced CH₄ and N₂O cumulative emissions compared with CK (by 193.6–226.5% and 37.5–43.7%, respectively) during rice growing season and intercropping period. Meanwhile, the mean values of global warming potentials (GWPs) from paddy fields with different cropping crops were T2 > T1 > CK. Considering the advantages of crop productivity together with environmental safety and soil quality, Chinese milk vetch-rice with cover crop residue returned would be the most practicable and sustainable cultivation pattern for the mono-rice cropping systems. Full article

Green manure application helps maintain soil fertility, reduce chemical fertilizer use, and carbon sequestration in the soil. Nevertheless, the application of organic matter in paddy fields induces CH₄ and N₂O emissions. Prolonging mid-season drainage reduces CH₄ emissions in paddy fields. Therefore, the combined effects of green manure application and mid-season drainage prolongation on net greenhouse gas emission (NGHGE) were investigated. Four experimental treatments were set up over a 2-year period: conventional mid-season drainage with (CMG) and without (CM) green manure and prolonged (4 or 7 days) mid-season drainage with (PMG) and without (PM) green manure. Astragalus sinicus L. seeds were sown in autumn and incorporated before rice cultivation. No significant difference in annual CH₄ and N₂O emissions, heterotrophic respiration, and NGHGE between treatments were observed, indicating that green manure application and mid-season drainage prolongation did not influence NGHGE. CH₄ flux decreased drastically in PM and PMG during mid-season drainage under the hot and dry weather conditions. However, increasing applied carbon increases NGHGE because of increased CH₄ and Rh. Consequently, combination practice of mid-season drainage prolongation and green manure utilization can be acceptable without changing NGHGE while maintaining grain yield in rice paddy fields under organically managed rice paddy fields. Full article

Knowledge of baseline water use for irrigated crops in the U.S. Southwest is important for understanding how much water is consumed under normal farm management and to help manage scarce resources. Remote sensing of evapotranspiration (ET) is an effective way to gain that knowledge: multispectral data can provide synoptic and time-repetitive estimates of crop-specific water use, and could be especially useful for this arid region because of dominantly clear skies and minimal precipitation. Although multiple remote sensing ET approaches have been developed and tested, there is not consensus on which of them should be preferred because there are still few intercomparison studies within this environment. To help build the experience needed to gain consensus, a remote sensing study using three ET models was conducted over the Central Arizona Irrigation and Drainage District (CAIDD). Aggregated ET was assessed for 137 wheat plots (winter/spring crop), 183 cotton plots (summer crop), and 225 alfalfa plots (year-round). The employed models were the Satellite-Based Energy Balance for Mapping Evapotranspiration with Internalized Calibration (METRIC), the Two Source Energy Balance (TSEB), and Vegetation Index ET for the US Southwest (VISW). Remote sensing data were principally Landsat 5, supplemented by Landsat 7, MODIS Terra, MODIS Aqua, and ASTER. Using district-wide model averages, seasonal use (excluding surface evaporation) was 742 mm for wheat, 983 mm for cotton, and 1427 mm for alfalfa. All three models produced similar daily ET for wheat, with 6–8 mm/day mid-season. Model estimates diverged for cotton and alfalfa sites. Considering ET over cotton, TSEB estimates were 9.5 mm/day, METRIC 6 mm/day, and VISW 8 mm/day. For alfalfa, the ET values from TSEB were 8.0 mm/day, METRIC 5 mm/day, and VISW 6 mm/day. Lack of local validation information unfortunately made it impossible to rank model performance. However, by averaging results from all of them, ET model outliers could be identified. They ranged from −10% to +18%, values that represent expected ET modeling discrepancies. Relative to the model average, standardized ET-estimators—potential ET (ET ${}_{\circ }$ ), FAO-56 ET, and USDA-SW gravimetric-ET— showed still greater deviations, up to 35% of annual crop water use for summer and year-round crops, suggesting that remote sensing of actual ET could lead to significantly improved estimates of crop water use. Results from this study highlight the need for conducting multi-model experiments during summer-months over sites with independent ground validation. Full article

In Iran, as in the rest of the world, land and water for agricultural production is under pressure. Integrating irrigation and drainage management may help sustain intensified agriculture in irrigated paddy fields. This study was aimed to investigate the long-term effects of such management strategies in a newly subsurface drained paddy field in a pilot area in Mazandaran Province, northern Iran. Three strategies for managing subsurface drainage systems were tested, i.e., free drainage (FD), midseason drainage (MSD), and alternate wetting and drying (AWD). The pilot area consisted of subsurface drainage systems, with different combinations of drain depth (0.65 and 0.90 m) and spacing (15 and 30 m). The traditional surface drainage of the region’s consolidated paddy fields was the control. From 2011 to 2017, water table depth, subsurface drainage system outflow and nitrate, total phosphorous, and salinity levels of the drainage effluent were monitored during four rice- and five canola-growing seasons. Yield data was also collected. MSD and AWD resulted in significantly lower drainage rates, salt loads, and N losses compared to FD, with MSD having the lowest rates. Phosphorus losses were low for all three practices. However, AWD resulted in 36% higher rice yields than MSD. Subsurface drainage resulted in a steady increase in canola yield, from 0.89 ton ha⁻¹ in 2011–2012 to 2.94 ton ha⁻¹ in 2016–2017. Overall, it can be concluded that managed subsurface drainage can increase both water productivity and crop yield in poorly drained paddy fields, and at the same time reduce or minimize negative environmental effects, especially the reduction of salt and nutrient loads in the drainage effluent. Based on the results, shallow subsurface drainage combined with appropriate irrigation and drainage management can enable sustained agricultural production in northern Iran’s paddy fields. Full article

Environmental and socio-economic evaluations that imply techniques for mitigating greenhouse gas (GHG) emissions from rice cultivation are a challenging and controversial issue. This study was designed to investigate the potential use of mitigation techniques for rice cultivation. Mid-season drainage (MD), using ammonium sulfate instead of urea (AS), and site-specific nutrient management (SSNM) were chosen as mitigation techniques. Data were collected using field surveys and structured questionnaires at the same 156 farms, covering four crop years. The GHG emissions were evaluated based on the concept of the life cycle assessment of the GHG emissions of products. The farmers’ assessments of mitigation techniques, with multiple criteria evaluation, were obtained by face-to-face interviews. Opinions on all mitigation techniques were requested two times covering four years with the same 156 farm owners. The multinomial logistic regression model was used to examine the factors influencing the farmers’ decisions. The results show that SSNM was evaluated as the highest abatement potential (363.52 kgCO₂eq ha⁻¹), the negative value of abatement cost (−2565 THB ha⁻¹), and the negative value of the average abatement cost (−14 THB kgCO₂eq⁻¹). Among the different techniques, SSNM was perceived as the most suitable one, followed by MD and AS. Highly significant factors influencing decision making consisted of planted area, land size, farmer liability, farmer perception of yield, and GHG emissions. Subsidies or cost-sharing measures to convince farmers to adopt new techniques can enhance their practices, and more support for the development of water systems can increase their availability. Full article

Appropriate agricultural practices for carbon sequestration and emission mitigation have a significant influence on global climate change. However, various agricultural practices on farmland carbon sequestration usually have a major impact on greenhouse gas (GHG) emissions. It is very important to accurately quantify the effect of agricultural practices. This study developed a platform—the Denitrification Decomposition (DNDC) online model—for simulating and evaluating the agricultural carbon sequestration and emission mitigation based on the scientific process of the DNDC model, which is widely used in the simulation of soil carbon and nitrogen dynamics. After testing the adaptability of the platform on two sampling fields, it turned out that the simulated values matched the measured values well for crop yields and GHG emissions. We used the platform to estimate the effect of three carbon sequestration practices in a sampling field: nitrogen fertilization reduction, straw residue and midseason drainage. The results indicated the following: (1) moderate decrement of the nitrogen fertilization in the sampling field was able to decrease the N₂O emission while maintaining the paddy rice yield; (2) ground straw residue had almost no influence on paddy rice yield, but the CH₄ emission and the surface SOC concentration increased along with the quantity of the straw residue; (3) compared to continuous flooding, midseason drainage would not decrease the paddy rice yield and could lead to a drop in CH₄ emission. Thus, this study established the DNDC online model, which is able to serve as a reference and support for the study and evaluation of the effects of agricultural practices on agricultural carbon sequestration and GHG emissions mitigation in China. Full article