Drained Paddy Fields Research Articles

수수의 고휴점파 본수에 따른 생육특성과 수량 변화

본 연구는 건강 기능성 농산물로 각광을 받고 있으면서 수요와 재배면적이 점차 확대되고 있는 수수의 생산량 증대와 자급률 향상을 위한 체계적인 재배기술을 확립하기 위한 기초자료를 얻고자 고휴점파 본수에 따른 생육 및 수량에 관한 연구를 수행하였다. 1. 파종본수에 따른 초장에서 파종본수가 증가할수록 길어지는 경향이 뚜렷이 나타났으며 엽수에서는 파종본수가 가장 적은 1본 처리구에서 8.0개로 많았으며 엽수가 가장 적게 나타난 5본 처리구와 연차간 각각 1.4, 1.5개의 차이가 나타났다. 경태에서도 파종본수가 증가할수록 얇아지는 경향이 나타났으며 1본 처리구 대비 72.6, 74.3%의 차이가 나타났다. 2. 수확기의 간장은 1, 2년차 모두 파종본수가 증가할수록 길어지는 뚜렷한 경향이 나타났으며 가장 길게 나타난 5본 처리구 183, 188 cm와 가장 짧게 나타난 1본 처리구간 각각 41, 29 cm 차이가 나타났다. 간경에서는 1본 처리구에서 가장 굵은 19.18, 20.13 mm로 나타났으며 파종본수가 증가할수록 얇아지는 경향으로 나타났다. 3. 수량구성요소를 보면 이삭장 및 이삭당 종실수, 천립중 모두 연차간 파종본수가 적을수록 길고 많거나 무거운 것으로 나타났으며 수량에서는 연차간 파종본수가 2본 처리구에서 수량구성요소에서 높은 값을 보인 1본 처리구 보다 111%, 116% 높은 것으로 나타났다. This study was conducted to evaluate effect of plants number per hill (PNH) on growth and yield of sorghum in drained paddy field for 2 years. Crop growth and development and yield in the field was examined to know the efficiency of proposed cropping system. At seeding after 40 days, leaf number and stem diameter were highest at 1 PNH plot, on the other hands, plant height was at 5 PNH plot the <TEX>$1^{st}$</TEX> and <TEX>$2^{nd}$</TEX>, respectively. The harvest stage, 5 PNH plot was highest culm length of 183, 188 cm the <TEX>$1^{st}$</TEX> and <TEX>$2^{nd}$</TEX>, however, culm diameter was lowest. Culm length of sorghum was highest by 183, 188 cm at 5 PNH plot also, culm diameter was thickest by 19.18, 20.13 mm at 1 PNH, respectively. Yield components of ear length, seed number per ear and 1000-seed weight were highest at 1 PNH the <TEX>$1^{st}$</TEX> and <TEX>$2^{nd}$</TEX>, respectively. As yield of sorghum was highest at 2 PNH plot <TEX>$344kg{\cdot}10a^{-1}$</TEX>, <TEX>$382kg{\cdot}10a^{-1}$</TEX> yearly, respectively that it were in order of 1 PNH plot > 3 PNH plot > 4 PNH plot > 5 PNH plot.

Influence of subsurface drainage on the productivity of poorly drained paddy fields

Because of the relatively flat topography of Northern Iran consolidated paddy fields and inadequate natural drainage facilities, these lands are usually confronted with waterlogging due to periodic excess of water from rainfall during the wet months. The productivity of these areas could be greatly increased if their drainage problems were solved by subsurface drainage. Subsurface drainage may also facilitate the mid-season drainage (MSD), one of the water management methods during the rice growing season. A drainage pilot consisting of surface and subsurface drainage with different drain depths and spacings was designed at Sari Agricultural Sciences and Natural Resources University, Iran, to explore the effect of different drainage systems on the productivity of paddy fields. Rice cultivation was carried out during two cropping seasons, 2011 and 2012. In 2011, after rice harvest, canola seed was cultivated in the subsurface drained area. For MSD, the fields were drained 25 days after rice transplanting and remained drained for 7 days. Randomized complete block design was used to find the effect of drainage on crops. The implementation of MSD through subsurface drainage, significantly increased yield, yield components and growth parameters of rice. Rice yield of the subsurface drained area was approximately 1.22–1.66 and 1.32–1.7 times higher than that of the surface drained area in 2011 and 2012, respectively. Subsurface drainage provided better condition for canola cropping while, because of waterlogging, it was not possible under surface drainage. An economic analysis showed that the cost of installing subsurface drainage systems was readily justified by annual increased rice and canola yields. Based on the results, the introduction of the subsurface drainage resulted in an increase in both crop yield and cropping intensity in the study area.

短節間カボチャ ‘TC2A’ の水田転換畑での栽培における窒素施肥量および施肥回数の検討

短節間カボチャ ‘TC2A’ の栽培における窒素施肥量と施肥回数（1回の全量基肥もしくは基肥と雄花開花前の2回に分けての分施）について，北海道の水田転換畑での栽培を対象に生育，果実収量および品質の面から解析した．牛ふん麦わら堆肥 1 t/10a を施用した淡色黒ボク土の転換初年度の畑での栽培において，窒素施肥量が 8 kg/10a までは窒素施肥量が多くなるほど果実収量が高くなり，果実乾物率やデンプン含量が高くなることにより果実品質が向上する傾向を示した．窒素施肥量を 12 kg/10a としても果実収量や品質の向上は認められなかった．また，窒素施肥量が 8 kg/ 10a であっても，基肥 4 kg/10a と追肥 4 kg/10a の 2回に分施することで，基肥のみで施肥した場合と比較して，収穫時の茎葉の生体重が増加し，日焼け・腐敗果率が有意に低くなった．以上より，北海道の転換初年目の水田転換畑において，牛ふん堆肥 1 t/10a を施用した淡色黒ボク土での短節間カボチャ ‘TC2A’ 栽培では，窒素 8 kg/10a を上記のように分施することが適していると判断した．

Effects of Timing of Paddy Field Drainage for Foliage Treatment Herbicide Spraying and Nitrogen Top-dressing on the Growth and Yield of Dry Direct Seeded Rice in Hokkaido, Japan

Effects of Timing of Paddy Field Drainage for Foliage Treatment Herbicide Spraying and Nitrogen Top-dressing on the Growth and Yield of Dry Direct Seeded Rice in Hokkaido, Japan

Response of Millet and Sorghum to Water Stress in Converted Poorly Drained Paddy Soil

Millet and sorghum are major dryland cereal crops, however their growth and productivity is limited by soil water stress with varying intensity. The major objective of this study was to evaluate water stress of millet and sorghum yield under drainage classes of poorly drained soil and to test the effect of the installed pipe drainage in poorly drained paddy soil to minimize crop stress. The research was carried out in poorly drained paddy fields located at alluvial slopping area resulting in non-uniform water content distribution by the inflow of ground water from the upper part of the field. Stress Day Index (SDI) was determined from a stress day factor (SD) and a crop susceptibility factor (CS). SD is a degree of measurement by calculating the daily sum of excess water in the profile above 30cm soil depth (<TEX>$SEW_{30}$</TEX>). CS depends on a given excess water on crop stage. The results showed that sum of excess water day (<TEX>$SWD_{30}$</TEX>) used to represent the moisture stress index was lower on somewhat poorly drained soil compared with poorly drained soil on 117 days. CS values for sorghum were 57% on <TEX>$3^{rd}$</TEX> leaf stage, 44% on <TEX>$5^{th}$</TEX> leaf stage, 37% on panicle initiation, 23% on boot stage, and 16% on soft dough stage. For proso millet CS values were 84% on <TEX>$3^{rd}$</TEX> leaf stage, 70% on <TEX>$5^{th}$</TEX> leaf Stage, 65% on panicle initiation, 53% on boot stage, and 28% on soft dough stage. And for foxtail millet the values were 73% on <TEX>$3^{rd}$</TEX> leaf stage, 61% on <TEX>$5^{th}$</TEX> leaf stage, 50% on panicle initiation, 29% on boot stage, and 15% on soft dough stage. SDI of sorghum and millet was more susceptible to excess soil water during panicle initation stage more poorly drained soil than somewhat poorly drained soil. Grain yield was reduced especially in proso millet and Foxtail millet compared to Sorghum.

Effect of subsurface drainage on water balance and water table in poorly drained paddy fields

The hydrological effects of different drainage systems were investigated as a pilot study in 4.5ha of paddy fields of Sari Agricultural Sciences and Natural Resources University, located at Mazandaran province, Northern Iran (36.3°N, 53.04°E), during two successive growing seasons of rice and canola from July 2011 to May 2012. Experimental treatments were: three conventional subsurface drainage systems including drainage system with drain depth of 0.9m and drain spacing of 30m (D0.9L30), drain depth of 0.65m and drain spacing of 30m (D0.65L30), and drain depth of 0.65m and drain spacing of 15m (D0.65L15); a bi-level subsurface drainage system with drain spacing of 15m and drain depths of 0.65 and 0.9m as alternate depths (Bilevel), and surface drainage system (Control). Water balance components were determined in both rice and canola crop seasons. Measurements of water table depth and subsurface drainage discharge were made daily during drainage periods. In the rice season, the total water supply was 754.6mm, of which 61.7% was lost by evapotranspiration and 16.2–19.1% was lost by deep percolation (DP). In the canola season, the treatments of D0.9L30, Bilevel, D0.65L30 and D0.65L15 were discharged, respectively, 44%, 51.5%, 43% and 60.5% of the total rainfall from the soil profile. Shallow drains were more effective in controlling water table compared with deep drains so that, average of measured water table depths in the representative observation wells of D0.9L30, Bilevel, D0.65L30, and D0.65L15 were 2.1, 15, 24.1, and 32.4cm, respectively. Also, values of SEW30 (sum of excess water) were 3461, 1498, 1038 and 450cm for D0.9L30, Bilevel, D0.65L30 and D0.65L15, respectively. Based on the results, water management through a subsurface drainage system could provide winter cropping condition in the study area.

복합영농 관개지구의 배수량 모의 모형의 개발

The objectives of this study were to develop a hydrologic simulation model to estimate surface drainage for irrigation districts consisting of paddy and protected cultivation, and to evaluate the applicability of the developed model. The model consists of three sub-models; agricultural supply, paddy block drainage, and protected cultivation runoff. The model simulates daily total drainage as the sum of paddy field drainage, irrigation canal drainage, and protected cultivation runoff at the outlets of the irrigation districts. The agricultural supply sub-model was formulated considering crop water requirement for growing seasons and agricultural water management loss. Agricultural supply was calculated for use as input data for the paddy block sub-model. The paddy block drainage sub-model simulates paddy field drainage based on water balance, and irrigation canal drainage as a fraction of agricultural supply. Protected cultivation runoff is calculated based on NRCS (Natural Resources Conservation Service) curve number method. The Idong reservoir irrigation district was selected for surface drainage monitoring and model verification. The parameters of model were calibrated using a trial and error technique, and validated with the measured data from the study site. The model can be a useful tool to estimate surface drainage for irrigated districts consisting of paddy and protected cultivation.

Quality and Yield Characteristics of Potato (Solanum tuberosum L.) Grown at Paddy Field in Spring Season

This study was conducted to determine the characteristics of quality and yield in potatoes grown at paddy field before rice transplantation during the spring season. Three potato cultivars ('Jowon', 'Haryeong', and 'Goun') were grown in Gangneung (asl 5 m) and Seocheon (asl 20 m). In both locations, weather condition belonged to the fourth zone (spring cropping) in potato production location's distribution of Korea. Daily mean soil temperature in both the locations was <TEX>$0.2-0.6^{\circ}C$</TEX> lower than air temperature, while soil moisture was adequate level to potato growth in spite of spring drought. TR ratio was not affected by location, but by cultivar. Specific gravity, starch content, dry matter rate, and yield were significantly influenced by location and by cultivar. There was no difference in total tuber number by location, however there was a large gap in marketable tuber yield according to locations and cultivars. There were high negative relationships between yield and main qualities such as dry matter rate and starch content, while high positive correlation was observed between main qualities. It was possible to produce potato before rice transplanting at drained paddy fields located in representative two locations of potato spring cropping and their characteristics in growth and quality were similar to those generally well known in upland cultivation. Paddy field was thought to be more favorable than upland in terms of available soil moisture supply against spring drought. Further research, however, was needed to increase soil temperature and also preliminary review on proper cultivar according to location seemed to be needed for high yield.

Effects of Different Paddy Field Drainage Degrees and Panicle Nitrogen Fertilizer Managements on Photosynthetic Productivity and Nitrogen Utilization of Rice under Triangle-Planted System of Rice Intensification

The effects of different paddy field drainage degrees including three soil water content levels(0-20 cm soil relative water content was controlled at 80%±5%,60%±5%,and 40%±5%,named W 1,W 2,and W 3 respectively) and three panicle nitrogen fertilizer managements(the first panicle nitrogen fertilizer was applied on the 1st,8th,and 15th days after rewatering,named S 1,S 2,and S 3,respectively) on photosynthetic productivity during filling stage and nitrogen utilization of rice were investigated using medium hybrid rice Ⅱ you 498 under triangle-planted system of rice intensification(TSRI).The results showed that there was an obvious interaction to photosynthetic productivity,dry matter accumulation and nitrogen uptake,translocation and utilization between paddy field drainage degree and panicle nitrogen fertilizer management.Paddy field drainage had the most significant effect compared with panicle nitrogen fertilizer management.Canopy apparent photosynthetic rate at 15 days and 30 days and effective panicle number were decreased,under the treatment of applying the first panicle nitrogen fertilizer on the 1st day after rewatering,and canopy apparent photosynthetic rate at 15 days and 30 days after heading,harvest index and N production efficiency were increased under the treatment of applying the first panicle nitrogen fertilizer on the 8th or 15th day after rewatering in lower paddy field drainage condition(W 1).The treatment with higher paddy field drainage condition(W 2,W 3) applying the first panicle nitrogen fertilizer on the 1st or 8th days after rewatering was favorable to improve flag leaf photosynthetic rate at booting and full heading stages,canopy apparent photosynthetic rate at 15 days and 30 days after heading,dry matter accumulation,grain yield and its components,and nitrogen accumulation and utilization.From the comprehensive analysis and comparison,W 2 S 1 is the optimum combination for moderate paddy field drainage degree and panicle nitrogen fertilizer management under theTSRI,and its grain yield reached 10.96 t ha-1.

A new framework for study of irrigated paddy rice and upland crops rotation farming and its relation to soil and plant nutrition science : 2. Expectations of integrated manuring technology for productive soybean cultivation on drained paddy fields

A new framework for study of irrigated paddy rice and upland crops rotation farming and its relation to soil and plant nutrition science : 2. Expectations of integrated manuring technology for productive soybean cultivation on drained paddy fields

A new framework for study of irrigated paddy rice and upland crops rotation farming and its relation to soil and plant nutrition science : 4. The declines of soil fertility of drained paddy fields under crops rotation and its fertility management

A new framework for study of irrigated paddy rice and upland crops rotation farming and its relation to soil and plant nutrition science : 4. The declines of soil fertility of drained paddy fields under crops rotation and its fertility management

Nitrogen accumulation in soybean [Glycine max (L.) Merr.] is increased by manure compost application in drained paddy fields as a result of increased soil nitrogen mineralization

The application of manure compost is an effective way to increase soybean [Glycine max (L.) Merr.] yield and nitrogen (N) fertility in drained paddy fields. We investigated changes in soil N mineralization during soybean cultivation using reaction kinetics analysis to determine the contribution of increased N mineralization after manure compost application (at a rate of 0 to 6 kg m−2) on N accumulation and seed yield of soybean under drained paddy field conditions. The seed yield and N accumulation decreased markedly in the second and third year of the experiment, but soil N mineralization increased in both years. No decrease in soil N mineralization occurred even after two soybean crops. Soil N availability was not the main cause of decreased soybean yield in the second and third years. The differences in plant aboveground N content between plots with and without manure compost was similar to the increase in N mineralization caused by manure compost application in the second and third years. The application of 6 kg m−2 of manure compost increased the amount of ureide-N and nitrate-N in soybean in the third year. Our results suggest that manure compost application increases soil N mineralization and soybean N2 fixation, resulting in increased N accumulation and seed yield. However, the soybean yield remained less than 300 g m−2 in the second and third years (i.e., below the yield in the first year) at all levels of manure compost application due to the remarkable decrease of N accumulation in the second and the third crops.

배수불량 경사지 논 토양의 배수방법에 따른 토양 물리성 변화

경사지 배수불량 논에서 밭작물의 안정적인 재배를 위한 배수개선 방법을 개발하기 위하여 논둑아래 기저부에 1열로 명거 (겉도랑 배수), 비닐차단막, 암거 (속도랑 배수), 관다발 등 네 가지 종류의 배수시설을 설치하여 배수개선 방법에 따른 토양의 물리적 특성변화를 비교 분석한 결과 다음과 같은 결론을 얻었다. 배수방법별 토양의 용적밀도는 배수방법 간에 큰 차이가 없었으나 집적층 (B층)의 투수력은 암거배수구가 <TEX>$2.67cm\;hr^{-1}$</TEX>로 가장 높았고 다음은 관다발배수 <TEX>$1.53cm\;hr^{-1}$</TEX>이었으며, 명거배수, 비닐차단막은 <TEX>$0.8cm\;hr^{-1}$</TEX>내외로 낮은 경향을 보였다. 경작층 (Ap)의 액상은 명거배수, 비닐차단막 처리구가 35% 내외로 높은 경향을 보였으나 암거배수구에서는 수분함량이 크게 감소되었다. 또한 암거배수구의 기상은 32 ~ 35% 내외로 명거배수, 비닐차단막, 관다발 처리구 17 ~ 20% 보다 상대적으로 높아 공극률이 증가하는 것으로 나타났다. 명거배수 처리구의 토색은 수분과다와 높은 지하수위로 환원작용이 일어나 회색을 보인 반면 암거배수구에서는 투수성 및 통기성이 증가하여 회색층의 토색이 명갈색을 변화되었고 환원층의 출현 깊이가 깊어지고 점차 층위분화가 진행됨을 확인할 수 있었다. 강우 후 토양 깊이별 수분함량 변화를 분석한 결과 명거배수 처리구의 표토에서는 7일이 경과하여야 토양수분이 30 mm이하로 감소되었으나 20 cm 이하의 깊이에서는 항상 수분이 과잉된 상태로 지속되는 경향을 보였다. 반면 암거 배수 처리구에서는 강우 후 5 일이 경과 후에 토양 30 cm 깊이까지 수분함량이 30 mm 이하로 감소되어 배수개선 효과가 가장 높았다. 따라서 "배수불량"인 경사지 논에서 논둑 밑 1열의 암거배수 시설 설치가 명거배수, 비닐차단막, 관다발 배수방법에 비해 토양의 물리성 개선효과가 높아 밭작물의 안정적인 생산과 농지자원의 이용전환 즉 논을 밭으로 이용해야 하는 범용농지 기반 조성을 위한 저비용의 실용적인 배수개선 방법으로 이용성이 높은 것으로 판단되었다. The lower portion of sloping paddy fields normally contains excessive moisture and the higher water table caused by the inflow of ground water from the upper part of the field resulting in non-uniform water content distribution. Four drainage methods namely Open Ditch, Vinyl Barrier, Pipe Drainage and Tube Bundle for multiple land use were installed within 1-m position from the lower edge of the upper embankment of sloping alluvial paddy fields. This study was conducted to evaluate soil physical characteristics by drainage improvement in poorly drained sloping paddy field. The results showed that subsurface drainage by Pipe Drainage improves the productivity of poorly drained soils by lowering the water table and improving root zone soil layer condition. In an Pipe drainage plot, soil moisture drained faster as compared to the other drainage methods. Infiltration rate showed high tendency to Piper Drainage method about <TEX>$20.87mm\;hr^{-1}$</TEX> than in Open Ditch method <TEX>$0.15mm\;hr^{-1}$</TEX>. And Similarly soil water and degree of hardness and shear strength phase of soil profile showed a tendency to decrease. From the above results, we found that when an subsurface drainage was established with at 1m position from the lower edge paddy levee of the upper field in sloping poorly drained paddy fields Pipe Drainage was the most effective drainage system for multiple land use.

Vertical migration and distribution of added dissolved iron in Carex lasiocarpa marsh soil

Irrigating rice paddy fields with groundwater containing iron is standard practice for dry croplands replanted to rice in northeast China. To assess the impact of paddy field drainage on the receiving natural wetlands, vertical migration and distribution of dissolved iron in the soil–plant system with acidic dissolved iron addition were investigated in the Carex lasiocarpa marsh soil columns (diameter 35cm, height 65cm) of the Sanjiang Plain. The experiment was designed as four sequential stages: (1) iron-free leaching, (2) neutral iron addition using FeSO4 (100mgL−1 of iron concentration), (3) acidic iron addition using FeSO4 and HCl (200mgL−1 of iron concentration, pH adjusted to 3.56) and (4) iron-free leaching. After the experiment, the iron distribution within a natural wetland ecosystem was quantitatively observed. The results showed that pH and Eh in the soil columns were affected more by water table fluctuations than acidic addition. Effects of iron addition on the dissolved iron in soil solutions decreased with increasing soil depth, and the vertical migration rates in 20–30cm layer (AG horizon) and 30–50cm layer (G horizon) were 0.58 and 0.56mmmin−1, respectively. Doubling the iron addition did not increase the iron in soil solutions significantly. Only a small part of added iron (5.7%) drained out, while the majority was retained in soil (69.4%) and plant biomass (24.8%). Soil manganese and nitrogen were positively affected by acidic iron addition, while the effects on carbon and phosphorus were not significant.

Eco-Remediation of Branch River in Plain River-Net at Estuary Area

As an important pollution control unit in the downriver of Liaohe river, there are developing river-net in the estuary area with the horizontal radiatiform geomorphology. The surface water system poses the typical plain river-net characteristics. Under the complex hydraulic effect, the industrial wastewater, streamflow and paddy field drainage flow into the main stream of Liaohe river through various grade branch rivers or ditches. These can threat the offshore water quality of Liaodong bay seriously. In this study, a kind of combined technology composed of floating baffling bio-reactor (FBBR), multiple plant floating-bed and denitrify ecological aquatic weed (Aqu-Mat), was researched using scale and field experiments according to the pollution characteristics and spatial structure of the river-net. And then the suitable technological parameters were obtained. The main results can supply an optional method for the eco-remediation of Branch River in Plain River-net at Estuary Area.

Soil CO 2 fluxes from direct seeding rice fields under two tillage practices in central China

Agricultural practices affect the production and emission of carbon dioxide (CO 2) from paddy soils. It is crucial to understand the effects of tillage and N fertilization on soil CO 2 flux and its influencing factors for a better comprehension of carbon dynamics in subtropical paddy ecosystems. A 2-yr field study was conducted to assess the effects of tillage (conventional tillage [CT] and no-tillage [NT]) and N fertilization (0 and 210 kg N ha −1) on soil CO 2 fluxes during the 2008 and 2009 rice growing seasons in central China. Treatments were established following a split-plot design of a randomized complete block with tillage practices as the main plot and N fertilizer level as the split-plot treatment. The soil CO 2 fluxes were measured 24 times in 2008 and 17 times in 2009. N fertilization did not affect soil CO 2 emissions while tillage affected soil CO 2 emissions, where NT had similar soil CO 2 emissions to CT in 2008, but in 2009, NT significantly increased soil CO 2 emissions. Cumulative CO 2 emissions were 2079–2245 kg CO 2–C ha −1 from NT treatments, and 2084–2141 kg CO 2–C ha −1 from CT treatments in 2008, and were 1257–1401 kg CO 2–C ha −1 from NT treatments, and 1003–1034 kg CO 2–C ha −1 from CT treatments in 2009, respectively. Cumulative CO 2 emissions were significantly related to aboveground biomass and soil organic C. Before drainage of paddy fields, soil CO 2 fluxes were significantly related to soil temperature with correlation coefficients ( R) of 0.67–0.87 in 2008 and 0.69–0.85 in 2009; moreover, the Q 10 values ranged from 1.28 to 1.55 and from 2.10 to 5.21 in 2009, respectively. Our results suggested that NT rice production system appeared to be ineffective in decreasing carbon emission, which suggested that CO 2 emissions from integrated rice-based system should be taken into account to assess effects of tillage.

Optimum System of the Mechanization for Job's tears Production in Drained Paddy Field

Optimum System of the Mechanization for Job's tears Production in Drained Paddy Field

Growth Parameters and Seed Yield Compenets by Seeding Time and Seed Density of Non-/Few Branching Soybean Cultivars in Drained Paddy Field

Growth Parameters and Seed Yield Compenets by Seeding Time and Seed Density of Non-/Few Branching Soybean Cultivars in Drained Paddy Field

Irrigation ponds: Possibility and potentials for the treatment of drainage water from paddy fields in Zhanghe Irrigation System

Excessive application of fertilizers and pesticides as well as discharge of undecontaminated and unrecycled waste of livestock and poultry into farmland has caused serious non-point source pollution (NSP) of farmland in China. With the traditional mode of irrigation and drainage in rice-based irrigation systems, the pollution of farmland drainage water has become more and more serious. Traditional irrigation and drainage systems only focus on issues concerning water quantity, i.e. the capacity of irrigation in drought and drainage in waterlogging period, yet have no requirement on water quality improvement. how to clean the water quality of farmland drainage through remodeling the existing irrigation and drainage systems has a very important realistic meaning. Pond is an important irrigation facility in rice-based irrigation systems in southern China, which has the functions of not only a storage of water from canals but also collections of surface runoffs and farmland drainage for recycling use. Such water storage features of pond provide the possibility and potential capacity for drainage water treatment by managing such features as treatment basins as the growth of aquatic plants as well as living of fishes, batrachia and microorganisms in pond forms a soil-plant-microorganism ecological system. To explore the potential capacity of pond for drainage water nutrient reduction, the Zhanghe Irrigation System of Hubei, a typical “melon-on-the-vine” system in southern China is selected as the research site. The results of pond survey and field experiments demonstrate that plenty of ponds are suitable for collecting and cleaning paddy field drainage, and the ponds are favorable in reducing N, P nutrients in the drainage water. Other issues, e.g. how to maximize such capacity and what strategies should be sought to make existing treatment basins hydraulically more efficient, are also discussed.

Removal of Nutrients, Organic Matter and Heavy Metals from Paddy Field Drainage by Charcoal

This study examined the ability of charcoal to remove organic matter, nutrients and heavy metals from agricultural drainage. Water treatment equipment containing wood charcoal was installed in a test paddy field. Concentrations of total organic carbon (TOC), total nitrogen (TN), total phosphorus (TP) and heavy metals (Cr, Fe, Zn and Pb) in water samples taken before and after passing through the equipment were analyzed. The equipment was installed simply at the outlet in the test field and removed environmental load substances during a contact time of more than one hour. The reduction rates of TOC and TN ranged from 20 % to 40 %. The reduction rate of TP ranged from 20 % to 90 %. The reduction rates of metals (Cr, Fe, Pb) ranged from 23 % to 62 %. These results suggest that charcoal can be used in water treatment equipment to treat paddy field drainage water.