Drained Paddy Fields Research Articles

Effects of drainage intensity on water and nitrogen use efficiency and rice grain yield in a semi-arid marshland in Rwanda

ABSTRACT Drainage management is important in intensification of irrigated paddy rice production. This study assessed the effects of drainage intensity on water and nitrogen use efficiency and rice grain yield in a field experiment conducted during three seasons in Rwanda. The experiment comprised 12 plots with four blocks and three treatments: DS0.6 (0.6 m deep drain), DD11.2 (1.2 m deep drain, control structure open four times per week), and DD21.2 (1.2 m deep drain, control structure open two times per week). Outflow was calculated from water balance. Nitrogen (N) content in drainage water was determined weekly. Crop yield and N uptake were determined in grain and straw. In all seasons, grain yield was 61–131% higher, crop N uptake was 24–90% higher, harvest index (HI) was 24–65% higher and water use efficiency (WUE) was 50–150% higher in treatments DD11.2 and DD21.2 than in DS0.6. There was a decrease in soil carbon/nitrogen ratio at the end of Seasons 2 and 3. Recirculating straw to fields is thus necessary to replenish SOC for long-term soil fertility. A practical implication of the study is that managed deep drainage systems could enhance water use efficiency and rice grain yield in poorly drained paddy fields.

Chronic urban hotspots and agricultural drainage drive microbial pollution of karst water resources in rural developing regions

Contamination of surface and groundwater systems with human and animal faecal matter leads to exposure of reliant populations to disease causing micro-organisms. This exposure route remains a major cause of infection and mortality in developing countries, particularly rural regions. To meet the UN's sustainable development goal 6: Ensure availability and sustainable management of water and sanitation for all, we need to identify the key controls on faecal contamination across relevant settings. We conducted a high-resolution spatial study of E. coli concentration in catchment drainage waters over 6 months in a mixed land-use catchment in the extensive karst region extending across impoverished southwest China. Using a mixed effects modelling framework, we tested how land-use, karst hydrology, antecedent meteorological conditions, agricultural cycles, hydrochemistry, and position in the catchment system affected E. coli concentrations. Land-use was the best predictor of faecal contamination levels. Sites in urban areas were chronically highly contaminated, but water draining from agricultural land was also consistently contaminated and there was a catchment wide pulse of higher E. coli concentrations, turbidity, and discharge during paddy field drainage. E. coli concentration increased with increasing antecedent rainfall across all land-use types and compartments of the karst hydrological system (underground and surface waters), but decreased with increasing pH. This is interpreted to be a result of processes affecting pH, such as water residence time, rather than the direct effect of pH on E. coli survival. Improved containment and treatment of human waste in areas of higher population density would likely reduce contamination hotspots, and further research is needed to identify the nature and distribution of sources in agricultural land.

Modern Farming Practices in Paddy Fields Negatively Affect an Endemic Frog, Glandirana susurra, in Japan

Paddy fields play an important role as alternative habitats for various wetland-dependent species. Agricultural intensification in paddy fields, however, presents serious threats to these species. Here, we examined the environmental factors, including those related to modern farming practices, affecting the distribution of the Sado wrinkled frog (Glandirana susurra) in paddy fields on Sado Island, Japan. We recorded the abundance of frogs at 42 sites in early and late June 2014 and investigated the species’ responses to several local and landscape-scale variables. We found that frog abundances decreased sharply following the drainage of paddy fields in mid-June and were negatively associated with deep concrete irrigation ditches that surrounded the paddies. The addition of conservation ditches built into rice paddy fields, however, was shown to mitigate against the effects of the drainage. Our results suggest that conservation ditches serve as refuges for G. susurra. We propose that decreasing the depth of irrigation ditches or providing structures for frogs to use and traverse the ditches could be useful approaches that help conserve G. susurra. We also suggest the increased use of conservation ditches and implementation of aquatic biotopes in the surrounding landscape might serve to aid this species’ long-term conservation.

Influence of precipitations and sunshine hours on yield of paddy field grown wheat (Triticum aestivum L.) in Northern Kyushu, Japan

ABSTRACTRelationships between wheat (Triticum æstivum L.) yield components and growing season weather conditions (e.g. temperature, precipitation, and sunshine duration) were investigated for a rice-wheat rotation paddy system situated in Northern Kyushu, Japan over a 17-year period (2000–2016). A 1.0 mm increase in precipitation from 21 to 32 days after sowing decreased wheat yield by about 27 kg ha−1 at early seedling stage with one to two leaves (Zadoks (Z) growth stage Z1.1–1.2). Number of tillers and spikes showed significant negative correlations to the amount of precipitation during the period. An hour increase in mean daily sunshine hours from 94 to 111 days after sowing resulted in an 328 kg ha−1 rise in grain yield at stem elongation stage with the first and second node detection (Z3.1–3.2). The grain number per square meter also showed strong positive correlations to sunshine hours during the same period. However, this positive effect of sunshine was negated when precipitation exceeded about 30 mm during the early seedling stage. Consequently, precipitations at early seedling stage and sunshine hours at stem elongation stage mostly determined wheat yield in Northern Kyushu paddy field. Increasing precipitations during the early seedling stage highlights the pressing need for effective paddy field drainage management from wheat sowing through harvest.Abbreviations: CP: Chikushi Plains; FARC: Fukuoka prefectural Agriculture and Forestry Research Center; SARC: Saga prefectural Agricultural Research Center; DAS: days after sowing

Feasibility of Controlled Drainage in Saline Vertisols of TBP Command Area of Karnataka, India

AbstractSubsurface drainage (SSD) improves crop productivity in canal command areas suffering from waterlogging and salinity problems. However, excessive drainage of paddy fields under conventional SSD is known to cause irrigation water shortage during critical growth stages of rice and also results in excessive leaching of nitrogenous fertilizers particularly at the tail end of the irrigation command. To overcome these problems farmers of the Tungabhadra Project (TBP) irrigation command used to block the outlets of lateral drains of the SSD system. In order to provide a lasting solution to this problem through a controlled drainage approach, a comparative field study was conducted on clay loam soil at the Agricultural Research Station (ARS), Gangavathi, over four seasons. In general, there was a reduction in drain discharge depth of 64% in the case of controlled drainage over conventional SSD, with an average irrigation water saving of about 17%. Average nitrogen loss was also reduced by 50.4% compared to conventional drainage. Paddy grain yield improvement was slightly higher (from 3.84 to 5.14 t ha−1) for conventional compared to controlled conditions (3.76–4.83 t ha−1). © 2019 John Wiley & Sons, Ltd. © 2019 John Wiley & Sons, Ltd.

Evaluating Drainmod‐s to Predict Drainage Water Salinity and Groundwater Table Depth During Winter Cropping in Heavy‐Textured Paddy Soils

AbstractSimulation models can quickly and cost‐effectively describe various aspects of management practices in newly reclaimed agricultural soils. In this research, the capability of the DRAINMOD‐S model was evaluated to predict the salinity of the subsurface drainage effluents in a newly subsurface drained paddy field during winter cropping. Measurements of groundwater table depths and drainage water salinity were taken in three conventional subsurface drainage systems at the Sari Agricultural Sciences and Natural Resources University, northern Iran, during three canola growing seasons (2011–2012, 2015–2016 and 2016–2017). The data were used to calibrate and validate the model. The model provided better predictions of groundwater table depths in shallower drainage systems. Measured and simulated drainage water salinities varied, respectively, from 620 to 1580 and 790–1430 mg l−1 in the calibration process and from 441 to 1640 and 656–1820 mg l−1 in the validation process. The differences between measured and simulated salt loads were in the range of 59–174 and 43–586 kg ha−1 in calibration and validation, respectively. The results indicated that DRAINMOD‐S can be used as a management tool to diminish environmental issues in heavy paddy soils from the viewpoint of salt load. © 2019 John Wiley & Sons, Ltd.

Characteristics of biochemical oxygen demand and chemical oxygen demand export from paddy fields during rainfall and non-rainfall periods

Rice growing in paddy fields equipped with irrigation and drainage systems is less affected by unfavorable weather patterns such as prolonged dry periods and severe storms, but for the same reason, the fields discharge water to maintain suitable water depths even between rainfall events. Studies have been done to examine the quality of water drained from rice paddy fields during or after rainfall events. However, it is not clear how drainage affects the water quality of downstream waterbodies, especially during non-rainfall periods. We investigated the water quality characteristics of rainfall and non-rainfall rice paddy drainage, which was characterized by biological oxygen demand (BOD) and chemical oxygen demand (COD). In this study, hydrological variables including water inflow/outflow rates, depth, BOD, and COD were monitored at a paddy field in Korea from 2008 to 2012. This study then quantified how BOD and COD loadings are controlled by irrigation and drainage management practices. Water quality measurements showed that rainfall events that resulted in rainfall depths greater than 50 mm are responsible for half of the overall BOD and COD loads discharged by rainfall events of the fields. On the other hand, a quarter of the total BOD and COD was attributed to events that provided rainfall depths less than 10 mm. The results suggested that the BOD and COD loads of rainfall events can be reduced by up to 25% if water at paddy fields is carefully managed in small rainfall events. Water samples taken during rainfall events had greater nutrient loads only by 6 kg BOD ha−1 (17 kg BOD ha−1 vs. 11 kg BOD ha−1) and 7 kg COD ha−1 (41 kg COD ha−1 vs. 34 kg COD ha−1) compared to those of the non-rainfall periods in the cropping season. Such a finding indicates the significant impacts of paddy field drainage practices on downstream water quality between rainfall events, particularly when considering a long period of non-rainfall. The monitoring data also showed that the standard unit load of 15.5 kg BOD ha−1 established for rice paddy fields by the Ministry of Environment, the environmental authority of Korea, is substantially different from the actual BOD load, because the non-rainfall BOD loads were not considered in the standard. Thus, this study suggests that non-rainfall BOD loads should be counted and managed for successful implementations of total maximum daily load programs.

Iron-Manganese (Oxyhydro)oxides, Rather than Oxidation of Sulfides, Determine Mobilization of Cd during Soil Drainage in Paddy Soil Systems.

The preharvest drainage of rice paddy fields during the grain filling stage can result in a substantial mobilization of Cd in soil and, consequently, elevated grain Cd concentration. However, the processes controlling the mobilization of Cd remains poorly understood. Using 12 field-contaminated paddy soils, we investigated the factors controlling the temporal changes in Cd solubility in paddy soils that were incubated anaerobically for 40 d followed by a 20 d oxidation period. Soluble and extractable Cd concentrations decreased rapidly upon flooding but increased during the oxidation phase, with Cd solubility (aqueous Cd/soil Cd) largely depending upon porewater pH. Furthermore, inhibiting sulfate reduction or inhibiting oxidation dissolution of Cd-sulfides had little or no effect on the mobilization of Cd in the subsequent oxidation phase. Both sequential extraction and X-ray absorption spectroscopy (XAS) analyses revealed that changes in Cd solubility were largely dependent upon the transformation of Cd between the Fe-Mn (oxyhydro)oxide fraction and exchangeable fraction. Mobilization of Cd upon soil drainage was caused by a decrease in soil pH resulting in the release of Cd from Fe-Mn (oxyhydro)oxides. Taken together, Fe-Mn (oxyhydro)oxides play a critical (and prevalent) role in controlling the mobilization of Cd upon soil drainage in paddy systems.

Study on nitrogen removal from rice paddy field drainage by interaction of plant species and hydraulic conditions in eco-ditches.

Eco-ditches (ecological ditches) not only drain water from rice paddies, but also facilitate the removal of nitrogen (N). We established an experiment with both static and flowing water in 2017 to observe N removal from rice paddy drainage by eco-ditches containing three different types of monoculture vegetation: Zizania aquatica, Canna indica L., and Pontederia cordata. Results showed that ammonia volatilization and plant uptake contributed little to N removal. Harvest of Z. aquatica from the eco-ditch during the late growing season had an appreciable effect on N removal. However, harvest of C. indica L. and P. cordata had negligible effects. During static test, the concentration of total N (TN) and ammonium N (NH4+-N) and the pH all decreased from the surface to the bottom of water. The concentration of nitrate N (NO3--N) did not exhibit stratification. In a flowing water experiment, ditches with Z. aquatica, C. indica L., and P. cordata had the following average removal rates: TN 15.8%, 11.6%, and 27.9%; NO3--N 4.2%, 8.4%, and 17.8%; NH4+-N 22.8%, 16.4%, and 37.5%, respectively. The removal rates of TN and NH4+-N decreased with the increase of water level, while that of NO3--N increased significantly. Nitrogen removal rates decreased with the increase of influent TN concentration or flow rate. Nitrogen removal rate of P. cordata ditch was highly dependent on the influent TN concentration, but the flow rate was not as important due to the great drag caused by its large density. While the contrary was observed in the C. indica L. ditch. For Z. aquatica ditch, both the flow rate and the TN concentration had a strong negative correlation with the N removal rate.

Improvement and testing of SWAT for multi-source irrigation systems with paddy rice

According to the hydrological characteristics of a multi-source irrigation system with paddy rice, the Soil and Water Assessment Tool (SWAT) is improved to develop a distributed hydro-agronomic model. A technique with three critical depths is incorporated to control the irrigation and drainage of paddy fields. In addition, the evapotranspiration (ET) of a paddy field is estimated based on two types of water storage conditions within SWAT. Specifically, we propose a multi-source auto-irrigation framework for SWAT to estimate agricultural irrigation water consumptions (AIWCs) from different water sources. Furthermore, we apply the improved SWAT to the Yangshudang (YSD) basin, located in the Zhanghe Irrigation System (ZIS) of southern China, and the simulation results are compared with the observed data as well as with those of the original SWAT. The results indicate that compared with the original SWAT, the Nash-Sutcliffe efficiency (NSE) of daily discharge increases from 0.48 to 0.80 in the calibration period and from 0.68 to 0.84 in the validation period; in addition, the NSE of the daily ET increases from −0.09 to 0.90, and other evaluation metrics also increase. Moreover, the percent bias (PBIAS) between the total AIWC simulated by the improved SWAT and the observed value is 2.75%, and that is −48.59% for the original SWAT. In particular, the improved SWAT estimates AIWCs from local water sources (ponds and rivers) and the main Zhanghe Reservoir, and the simulated AIWCs approximate the observed values. Therefore, the improved SWAT is more effective and suitable for the simulation of hydrological processes than the original SWAT in the multi-source irrigation systems with paddy rice, and it can estimate the AIWCs from different water sources, which can provide irrigation management decision support for irrigation managers.

Yield and dry matter dynamics of vegetative and reproductive organs in Japanese and US soybean cultivars

ABSTRACTRecently, US soybean cultivars have exhibited higher yields than Japanese soybean cultivars. To identify the determinants for this yield difference in reference to dry matter dynamics, recently developed US cultivars and Japanese commercial cultivars were cultivated in drained paddy fields in 2012 and 2013. The total dry matter (TDM) of each cultivar was measured at the initial seed-filling stage (R5), at 30 d after R5, and at maturity (R8). From R5 to R8, the DM of abscised leaves and petioles were measured. The actual HI (with abscised leaves and petioles) and apparent HI (without abscised leaves and petioles) were determined at R8. US soybean cultivars showed higher yields and apparent TDM (without abscised leaves and petioles) than did Japanese cultivars at R8. However, the difference in actual TDM (with abscised leaves and petioles) production was not significant between US and Japanese cultivars at R8. On the other hand, the actual HI was higher in US cultivars than in Japanese cultivars. US cultivars exhibited a higher TDM distribution to the pod before R5 and a higher pod growth rate from R5 to 30 d after R5. US cultivars tended to show greater crop growth rates (CGRs) from R5 to 30 d after R5. The higher yield in US cultivars was associated with the higher actual HI, which was considered attributable to a greater TDM productivity during the seed-filling period and higher DM distribution in the pod before R5.

Integrating Irrigation and Drainage Management to Sustain Agriculture in Northern Iran

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.

Reviewing classical studies in soil physics Two pioneer studies on surface and subsurface drainage of clayey paddy fields

Reviewing classical studies in soil physics Two pioneer studies on surface and subsurface drainage of clayey paddy fields

暖地型マメ科Aeschynomene americana L.の生育に伴う乾物消化率及び窒素含有率の推移

暖地型マメ科Aeschynomene americana L.の生育に伴う乾物消化率及び窒素含有率の推移

Nitrogen Losses in Paddy Field Drainage Modified by Different Water Level Regulations

Nitrogen Losses in Paddy Field Drainage Modified by Different Water Level Regulations

水田・里山放牧の展開と推進課題( 構造再編下の日本農業)

水田・里山放牧の展開と推進課題( 構造再編下の日本農業)

Effect of liming using a partial mixing technique on reductions in the seed cadmium levels for soybeans (Glycine max (L.) Merr.) under field conditions

ABSTRACTTo reduce the availability of soil cadmium (Cd) to soybeans (Glycine max (L.) Merr.), we employed a liming by partial mixing (PM) technique in two drained paddy fields on Gray Lowland soils, which had 0.1 mol L–1 hydrochloric acid-extractable Cd concentrations as high as 1.08 and 1.40 mg kg–1. Among the different application methods tested, PM application (PM2) using a width of 20 cm and a depth of 20 cm was found to be most appropriate for reducing the seed Cd concentration and to obtain the optimum yield at Site A. Under PM2, a liming rate of 38% of that for broadcast incorporated into the surface 15 cm layer (Bc) was suitable to reduce the seed Cd concentration at Site A, whereas the lime rate with PM2 was set at 50% of that for Bc (PM2-50) at Site B due to the higher availability of soil Cd. The root system was limited within the range of lime and fertilizer application for PM2 as well as PM2-50; thus, the lime and fertilizer were supplied successfully to the rooting zone. The soil pH value was lower under PM2 at Site A and PM2-50 at Site B compared with Bc, whereas the seed Cd concentration was lower for PM2 and PM2-50. This may be explained by the intensive uptake of calcium and magnesium with PM2 as well as PM2-50. The seed Cd concentration in the cultivar “Ryuhou” at the target pH of 6.5 was approximately 30% lower with PM2-50 than Bc at Site B. In addition, the average seed Cd concentrations in one cultivar and two lines, characterized by the lower Cd uptake with higher retention in roots and higher accumulation in leaves, were approximately 40% lower compared with “Ryuhou.” Thus, the combination of liming with PM2-50 at the target pH of 6.5 and a low-Cd cultivar (or lines) minimized the seed Cd concentration. The highest seed Cd concentration was found in the first year of soybean cultivation, which was considered to be caused by the release of Cd from organic nitrogen compounds during the nitrogen mineralization process.

Phosphorus balance and risk assessment in the rice–canola cropping system under different drainage strategies

ABSTRACTThis research was conducted to quantify total phosphorus (TP) losses in poorly drained-consolidated paddy fields equipped with different surface and shallow subsurface drainage systems including drain depth of 0.9 m and drain spacing of 30 m (D0.9L30), drain depth of 0.65 m and drain spacing of 30 m (D0.65L30), drain depth of 0.65 m and drain spacing of 15 m (D0.65L15), drain spacing of 15 m and drain depths of 0.65 and 0.9 m as alternate depths (Bilevel). Typical surface drainage system of consolidated paddy fields was also considered as conventional practice of the study area (control). The subsurface drained fields were under year-round crop production of rice-canola, while the surface drained fields experienced only rice cropping once a year. During three rice-canola-rice growing seasons, TP losses through drainage and leaching in the D0.9L30, Bilevel, D0.65L30, D0.65L15 and control treatments were respectively, 1.12, 0.98, 1.44, 1.53 and 24.48 kg ha−1, equivalent to about 3.9%, 3.4%, 5.1%, 5.3% and 85.7% of applied triple superphosphate fertilizer. In the rice growing seasons, TP losses through surface runoff were higher than those through subsurface drainage effluents. Shallow subsurface drainage systems were promising for the study area compared surface drainage as phosphorus risks were reduced by 79%, 77%, 64% and 57% through D0.9L30, Bilevel, D0.65L30 and D0.65L15, respectively. These results demonstrated that, by providing suitable condition for winter cropping, subsurface drainage systems can diminish concerns related to phosphorus losses from poorly drained paddy fields in the north of Iran.

Improvement of seedling establishment under flood condition by seed coating with molybdenum compounds for wheat and barley

Wheat and barley are often cultivated also in paddy fields in winter in Japan. The drainage of paddy fields is often poor. The seedling establishment of wheat and barley is more prone to become poor if it rains heavily after sowing. The flooding damage on seedling establishment is thought to be caused by many factors. The generation of sulfide ions in flooded and reduced soil is thought to be one factor of the flooding damage. In this study, the effect of seed coating with molybdenum compounds, which suppress the generation of sulfide ions, on the flooding damage of wheat and barley seedling establishment. Two poorly soluble molybdenum compounds were coated on wheat or barley seeds at different amounts. Coated seeds were sown in soil and soon flooded for 2 d at 20 °C. When seeds were not coated with molybdenum compounds, rates of seedling establishment were no more than 32%. However, when any molybdenum compounds of .05–.5 mol-Mo kg−1 were coated, seedling establishment was significantly improved and rates of seedling establishment were no less than 54%. However, when sown seed were not flooded, the establishment rates of the seeds, which were coated with a molybdenum compound of no less than .1 or .2 mol-Mo kg-1, were significantly decreased. Accordingly, coating of molybdenum compounds could improve the seedling establishment of coated seeds under flooded condition, but might impair the seedling establishment of coated seeds under unflooded condition.

Effects of Polyethylene Film Mulching and Planting Densities on Growth and Yield of Proso Millet (Panicum miliaceum L.)

ABSTRACT This study was conducted to evaluate effects of planting densities (60×10 cm, 60×15 cm, 60×20 cm) and PE mulching (polyethylene film mulching, non-mulching) on growth and yield of proso millet in drained paddy field for 2 years. In PE plots, culm length, culm diameter and fresh weight were higher than non-mulching plot. Additionally, spike length and seed weight per hill were also higher in PE plot but thousand seed weight was weightier in non-mulching plot. The yield of proso millet were increased with 10.0% and 15.5% at PE plot in 1st and 2nd, respectively. Culm diameter was thickest at 60×20 cm plot with 8.43 mm in 2nd however, culm length was longest at 60×10 cm plot with 130, 142 cm in 1st and 2nd, respectively. Plant height was higher by the increase of planting density. As plant density decreased, that spike length and seed weight per hill were increased. Yield of planting density were highest at 60×15 cm plot 265 kg․10a -1 , 253 kg․10a -1 yearly, respectively that it were in order of 60×15 cm plot > 60×10 cm plot > 60×20 cm plot.