Paddy Plots Research Articles

Alteration of Paddy Plots in the Rain-fed Paddy Field and Their Influences on Rice Production in Don Daeng Village, Northeast Thailand

Alteration of Paddy Plots in the Rain-fed Paddy Field and Their Influences on Rice Production in Don Daeng Village, Northeast Thailand

Development of the HSPF-Paddy model to estimate watershed pollutant loads in paddy farming regions

The Hydrological Simulation Program-FORTRAN (HSPF) was modified to simulate watershed pollutant loads in paddy farming regions. Dike height and the Dirac delta function were added to a modified HSPF code (HSPF-Paddy) to incorporate the behavior of ponded water and nutrients in rice paddy fields. HSPF-Paddy was validated by examining its application to a rice paddy plot (3000 m 2) and a watershed (1803 km 2) that contained a significant proportion of rice paddy fields (30%). The model efficiency at the plot scale was very high showing 0.52, 0.93, and 0.93 for ponded water depth, and accumulation of total nitrogen, and total phosphorus, respectively, and simulated values and observed data were in close agreement. Model efficiency was somewhat lower at the watershed scale showing 0.82, 0.78, 0.44, 0.61, and 0.63 for stream flow, temperature, 5-day biochemical oxygen demand, total nitrogen, and total phosphorus, respectively. However, model performance was generally within expectations, and generally model efficiency greater than 0.5 is deemed acceptable considering the complexity of the watershed in terms of size and land use. This comprehensive, dynamic model is applicable to a wide range of scales, from plot to watershed, and can be used to simulate various paddy field and watershed environmental conditions, including loads from point and nonpoint source pollution. It may be a practical alternative to the unit-load method for estimates of watershed pollution loads, especially in paddy farming regions, where nonpoint source pollution loads may be poorly estimated because of highly site-specific conditions. The application of HSPF-Paddy is recommended for watershed management and best management practices (BMPs) evaluation in paddy farming regions.

Characteristics of indicator microorganisms in paddy rice plots after reclaimed water irrigation

A study was performed to examine the effects of reclaimed-water irrigation on microorganism concentration in the ponded-water of paddy rice plots. Several treatments were used and each one was triplicated to evaluate the change of indicator microorganisms (total coliforms (TC), faecal coliforms (FC), and E. coli) concentrations in 2003 and 2004 growing seasons. Their concentrations increased significantly after irrigation, but decreased by approximately 45% in 24 h. It implies that agricultural activities such as ploughing and fertilising need to be practiced one or two days after irrigation, considering health risks. Treatments with UV-disinfected water irrigation, demonstrated significantly lower concentrations than others, including control plots where natural water was irrigated. The monitoring result from actual paddy rice fields and experimental paddy plots showed that concentrations of indicator microorganisms ranged from 10(2) to 10(5) MPN/100 mL. The field scale water reuse research project is in progress and national guidelines for reclaimed-water irrigation are under preparation in Korea. A comprehensive assessment of existing agricultural practices and a thorough monitoring in the fields as well as treatment plots are recommended to make national guidelines more representative.

Exposure risk assessment and evaluation of the best management practice for controlling pesticide runoff from paddy fields. Part 1: Paddy watershed monitoring

Rice pesticide concentrations in surface water along with hydrological balance and water management conditions were investigated in a paddy watershed of about 100 ha at the Sakura river basin in Tsukuba, Japan, for 3 years from April 2002. Monitoring on different hydrological scales ranging from a paddy plot up to a watershed determined the importance of water management associated with rainfall events and the cyclic irrigation for reducing pesticide discharge into aquatic environments. Surface drainage significantly increased as a response to rainfall events greater than about 1.5 cm day(-1). A total of 16 herbicides were detected in the stream water and their peak concentrations mostly occurred from early to mid-May following the pesticide application period. Two water management factors influencing the pesticide runoff from paddy fields were defined: excess water storage capacity (EWSC) and water holding period (WHP). Uncertainty analyses of pesticide discharge from a paddy plot for dymron (daimuron) and imazosulfuron (IMS) were performed using Monte Carlo simulation (MCS) with prescribed probability of rainfall and water management practice from observations over a period of 3 years. Application of an intermittent irrigation scheme with shallow water depth practice and high drainage gate to maintain the EWSC > 2 cm and increasing WHP from the current Japanese Agricultural Chemicals Regulation law of 3-4 days to at least 10 days were recommended for reducing the pesticide runoff from paddy fields in a monsoon region such as in Japan. The combination of good water management in field plots and small-scale water cycling is the best management practice for controlling pesticide discharge from paddy watersheds.

Concentration Profile of Nitrogen and Phosphorus in Leachate of a Paddy Plot during the Rice Cultivation Period in Southern Korea

The relationships between nitrogen (N) and phosphorus (P) concentrations in surface flooding water and those in the leachate of various soil depths were monitored, and temporal variation of leaching losses of N and P from a paddy plot during rice cultivation was estimated under the conditions of southern Korea. Even flooded conditions nitrification in subsurface soil was identified, but nitrate concentrations in leachate were less than 10 mg/L, the standard drinking water nitrate concentration set by the World Health Organization (WHO). The NO3‐N and ortho‐P concentrations in the leachate were generally higher than those in the surface flooding water. Field data implied that leaching losses would not be accurately estimated under the flooded conditions of the paddy field when using the N and P concentrations of surface flooding water and infiltration depth. The leaching losses of NO3‐N from paddy fields were high immediately after fertilization. The study results suggested that proper fertilization and irrigation strategies are required to reduce leaching losses of NO3‐N from paddy fields.

관개기 시험구 논에서의 오염물질의 농도특성

The pollutant concentrations at experimental paddy plots with three (excessive, standard, reduced) different fertilization rates were investigated during 2001-2002 irrigation seasons. Mean concentrations of pollutants in ponded water were not significantly different among three experimental plots, but the T-N concentrations in percolated water significantly depended on fertilization rates. The T-N, T-P and , concentrations in ponded water during early irrigation season (late May to mid-June) were much higher than those during later irrigation season likely due to fertilization and low uptake by young rice crops. The T-N concentrations decreased but the concentrations of T-P and , increased three days after tillering fertilization. The removal rates of T-N by paddy plots were for an excessive fertilization plot, for a standard fertilization plot, and for a reduced fertilization plot three days after tillering fertilization. On the other hand, T-P and , were released three days after tillering fertilization.

Evaluation of the management practice for controlling herbicide runoff from paddy fields using intermittent and spillover-irrigation schemes

Two water management practices, an intermittent irrigation scheme using automatic irrigation system (AI) and a spillover-irrigation scheme (SI), were compared for the fate and transport of commonly used herbicides, mefenacet (MF) and bensulfuron-methyl (BSM) in experimental paddy plots. Maximum mefenacet concentrations in paddy water were 660 and 540 μg L−1 for AI and SI plot, respectively. The corresponding values for bensulfuron-methyl were 46.0 and 42.0 μg L−1. Dissipation of the herbicides in paddy water appeared to follow the first-order kinetics with half-lives (DT50) of 1.9–4.5 days and DT90 (90% mass dissipation) of 7.8–11.3 days. The AI plot had no surface drainage, hence no herbicide was lost through paddy-water discharge. However, SI plot lost about 38 and 49% of applied mefenacet and bensulfuron-methyl, respectively. The intermittent irrigation scheme using automatic irrigation system with a high drainage gate was recommended to be a best management practice for controlling the herbicide losses from paddy fields. The paddy field managed by spillover-irrigation scheme may cause significant water and herbicide losses depending on the volume of irrigation and precipitation. The water holding period after herbicide application was suggested to be at least 10 days according to the DT90 index.

Nitrogen Removal in an Experimental Paddy Plot with Gravity Flow

Nitrogen Removal in an Experimental Paddy Plot with Gravity Flow

Analysis of Water Requirement Rate in Tilled and No-puddled Paddy Plots under Direct Seeding Culture

Analysis of Water Requirement Rate in Tilled and No-puddled Paddy Plots under Direct Seeding Culture

Land Consolidation Project for Huge Rice Paddy Plots in Case of the Community Farming System

Land Consolidation Project for Huge Rice Paddy Plots in Case of the Community Farming System

재처리수 관개후 지표미생물의 농도변화 조사

A study was performed to examine the effects of reclaimed-water irrigation on microorganism con-centration in ponded-water of paddy rice plots. Several treatments were used and each one was triplicated to evaluate the change of indicator microorganisms (total coliforms (TC), fecal coliforms FC), and E. coli) concentrations in 2003 and 2004 growing seasons. Their concentrations increased significantly right after irrigation, but decreased about <TEX>$45\%$</TEX> in 24 hours. It implies that agricultural activities such as plowing and fertilizing should be practiced one or two days after irrigation considering health-risks. Treatments with UV-disinfected water irrigation demonstrated significantly lower concentrations than others including control plots where natural surface water was irrigated. The monitoring results from actual paddy rice fields and experimental paddy plots showed that concentrations of indicator microorganisms ranged from <TEX>$10^2\;to\;10^5$</TEX> MPN/100mL. A comprehensive assessment of existing agricultural practices and a thorough monitoring in the field as well as treatment-plots are recommended to make more realistic national guidelines more applicable. UV-disinfected water irrigation reduced microorganism concentrations in paddy fields down to below the concentration of conventional paddy rice culture, and is thought to be an effective and feasible measure fur agricultural reuse of secondary effluent.

Delivery management water requirement for irrigation ditches associated with large-sized paddy plots in Korea

Delivery management water requirement (DMWR) is the use of bypass water in paddy field irrigation to help maintain desired water levels in irrigation canals and to distribute water to paddy plots in a uniform manner. Diverted irrigation water (DIW), DMWR, and the DMWR/DIW ratio were investigated for concrete lined irrigation ditches with large-sized paddy plots (100 m×100 m) during irrigation periods (May to mid-September). DIW and DMWR were measured at 5- to 10-day intervals at the inlets and outlets of irrigation ditches on stable water supply days. The mean DMWR/DIW ratios in irrigation ditches L1 and L2 over 3 years were 36 and 34%, respectively. The mean DMWR/DIW ratios displayed month-to-month and year-to-year variation. The monthly mean DMWR/DIW ratios were highest (55 and 71%) in June and lowest (<20%) in August and September. The annual mean DMWR/DIW ratios during a dry year markedly decreased to 11%, compared with 42% in other years. The decrease was due to the small DIW and farmers’ water management to maximize capture of limited irrigation water during the drought. The DMWRs in May and June were significantly (p<0.01) correlated with the DIWs, indicating that high DMWR in May and June are attributed to excessive DIW.

Agrochemical-Free, Direct-Sowing Culture of a Paddy with Non-Woven Fabric Mulch – Effect of Nitrogen Fertilizer –

The purpose of this study was to determine the effect of the amount of basal nitrogen fertilizer and topdressing with non-woven fabric mulch on a rice production system. Such characteristics as growth, dry matter production, nitrogen uptake, and grain yield were studied. During 2003, Koshihikari was grown in a field with this new method. Growth parameters such as leaf area index and crop growth rate were found to be higher for paddy plots that received topdressing treatments. Total top dry weight was slightly higher in topdressed plots, when compared to the plot with basal application. Nitrogen absorption was found to be higher in top dressing treated plots at heading time, and the nitrogen content in brown rice increased with this treatment. However, the topdressing treatment did not have an effect on leaf nitrogen percentages. In addition, we found no adverse effect (lodging) with the application of topdressing. We found that, as a result of the application of fertilizer amount and topdressing, grain yield remarkably increased. This increase occurred because such treatment produced higher values of these three features: leaf area index, crop growth rate, and number of grains. These results suggested that topdressing with non-woven fabric mulch for a direct-sowing rice production system produced effective results.

오리 순치방법이 논 방사후 행동과 벼 수량에 미치는 영향

오리농법에 있어서 논 방사 직후의 새끼오리는 물을 포함한 논 환경에 충분히 적응하지 못하고 폐사하거나 사람에 대한 도피행동에 의해 벼를 밟아 넘어뜨리는 등의 피해가 발생하고 있다. 또한 방사종료 후 오리포획에 있어서도 많은 시간과 노력이 소요되고 있다. 본 시험에서는 이와 같은 문제를 오리 육추시 특정의 사육관리를 통한 행동학적 측면에서 해결하고자, 논 방사할 오리에 대해 각인학습과 길들이기 등 온순한 관리를 행한 순치구, 거칠고 난폭하게 관리하면서 공포심을 부여한 조폭구 및 각인학습이나 길들이기, 공포심 등 사람과의 접촉경험이 거의 없는 대조구의 3 처리구로 구분하고, 오리의 행동유형, 성장 및 벼 수량성에 대하여 검토하였다. 오리의 행동유형에 있어서 논 방사직후의 채식과 이동행동은 조폭구 및 대조구에 비해 순치구에서 가장 많았고, 방사 2주 후의 채식과 이동행동에서는 순치구 및 조폭구보다 대조구에서 증가하는 경향을 나타내었다. 사람에 대한 도피반응거리에 있어서는 순치구에서 전혀 도피반응을 보이지 않았고, 조폭구보다 대조구에서 유의적으로 길게 나타났다. 오리 포획시간은 순치구에서 가장 짧았고, 다음으로 대조구, 조폭구의 순으로 나타났으며, 오리 순치방법에 따른 증체량에서는 처리구간에 큰 차이가 없었다. 벼 결주발생율은 대조구에 비해 순치구에서 유의적으로 적었고, 수량성에 대해서는 처리구간에 유의적인 차이는 인정되지 않았다. 이상의 시험결과를 종합해 볼 때, 오리 육추시 및 논 방사시의 각인학습과 온순한 관리는 벼의 결주 발생을 경감시키고, 오리가 사람에게 쉽게 순화되어 포획하는데 소요되는 시간과 노력이 현저하게 감소되는 것을 알 수 있었다. 그러나 논에서 오리의 노동행동과 벼 수량성에는 큰 영향을 미치지 않는 것으로 나타났다. Early introducing the ducks into the paddy field involves a variety of environmental changes such as new surroundings and contact with water, so that some free-ranged ducks show behavioral and physiological changes indicative of stress or die from not adapted for new circumstances. Moreover, the free-ranged ducks was tread on the rice plant, and required a great deal of labor and time for captured the ducks after finishing the introducing. The aim of the present study was to examine the effect of accustoming and imprinting of duckling on behavior patterns, body weight gain and yield of the rice plant in paddy fields. Three paddy plots were used as control (no imprinting and no contact with people), taming (imprinting and regular handling) and roughness (handling roughly and strike terror to ducks) plots. Right after introducing the ducks into the paddy field, eating and moving behaviour of taming plot ducks tended to be longer time spend than that of other treatments. However, eating and moving time tended to be longer in the control than that of other two treatments on the 2 weeks after. Flighting distance was not showed in the free-ranging period taming plot, but the control plot was significantly (P<0.05) longer than the roughness plot. The captured time of free-ranged ducks tended to be shorter in the order of taming, control and roughness plots. Body weight gains was not significant. The number of rice plants damaged by free-ranging ducks in the taming plot were significantly (P<0.05) less than that in the control plot, but the yield and yield components of the rice plant were not differ among 3 treatments. These results indicated that the imprinting or regular handling and related treatments of duckling was reducing badly damage of rice plants, captured time and labor of free-ranged ducks in paddy field, although the working behavior of ducks and yield ability of the rice plants were not affected.

Simulation model of rainfed rice production on sloping land in northeast Thailand

In northeast Thailand, the rapid expansion of rainfed paddy fields has decreased the stability of rice production. This paper describes a model that computes rice production on the basis of the hydrologic conditions of rainfed paddy fields on hill slopes. The model well expressed the hydrologic processes, rice yield, and production at the study site. We simulated rice production as uphill paddy plots are abandoned, increasing catchment area, under various rainfall conditions. The simulation showed that rice yield and stability increase as uphill plots are abandoned, although the total rice production decreases. Thus, the effect of catchment size on rice production in each plot was quantified. The model proved to be useful for analyzing rainfed rice production under various land and water conditions.

환경농업 시범마을 논에서 시비에 따른 무척추동물 개체 수 변화

This study was conducted to survey and identify kinds and population of the freshwater invertebrate fauna according to the managements of paddy rice fields at Ok-Chun and Yang-Pyung. The experiment was conducted in 4 paddy plots; conventional fertilization plot (CF), fertilization by prescription with soil testing with (ST+A) or without soil amendment (ST), and no fertilization as the control. In addition, the freshwater invertebrate fauna was also surveyed at 3 sections of as upper, intermediate and down, in both Jitan and Bungsan stream. The total number of the freshwater invertebrates was higher in the order of ST>CF>ST+A>C and ST>ST+A>CF>C at Ok-Chun and Yang-Pyung, respectively. The population density of aquatic insects was higher in plots fertilized by prescription with soil testing than in the other plots at both demonstration villages. The freshwater invertebrates collected in Jitan and Bungsan stream were identified and classified into 59 families and 90 species, and their population density was highest in the downstream among.

N and P losses from a paddy field plot in central Korea

The study was carried out to investigate the water balance and runoff and infiltration losses of nutrients in a paddy field plot located in southern Korea. Field monitoring was carried out during the cropping season from May 1, 1999 to September 30, 2000. The soil of the experimental paddy field belonged to the Jisan series (SiL; fine loam, mixed, mesic Fluventic Haplaquepts) covering on area of 5,000 m2 (100 m × 50 m). The measured input quantities of N and P into the paddy field were as follows: 122 and 140 kg N ha−1 and 29 and 30 kg P2O5 kg ha−1 from chemical fertilizer, 20 and 28 kg N ha−1 and 0.35 and 0.36 kg P ha−1 from precipitation, and 26 and 35 kg N ha−1 and 0.57 and 0.72 kg P ha−1 from irrigation water, respectively. The measured outputs of N and P during the study period were as follows: 48 and 52 kg N ha−1 and 1.1 and 1.6 kg P ha−1 from runoff water, and 9 and 12 kg N ha−1 and 0.04 and 0.05 kg P ha−1 from infiltration. The runoff loading was the highest in June, presumably because of the higher concentrations of chemical components associated with chemical fertilizer application. The runoff losses of nutrients were compared to the amounts of nutrients supplied by chemical fertilizers. It was found that the losses of N accounted for 34.3 and 42.6% of the chemical fertilizer applied, while those of P accounted for 3.8 and 5.3%. The ratio between nutrient losses by infiltration and the chemical fertilizer applied was 6.4 and 9.8% for N and 0.1 and 0.2% for P, respectively.

Adjustment of Tenanted Farmland to Consolidate Large-sized Paddy Plots

Adjustment of Tenanted Farmland to Consolidate Large-sized Paddy Plots

Consolidation of Large-sized Paddy Plots by Consolidation of Land Owners' Substitute Lots

Consolidation of Large-sized Paddy Plots by Consolidation of Land Owners' Substitute Lots

Impacts of agrochemical fertilizer on the aquatic environment of paddy fields in Vietnam

To evaluate the impacts of agrochemical fertilizer application on the aquatic environment of paddy fields in tropical regions, 7.04 ha of paddy field situated in northern Vietnam were selected as a study area. The fate of nutrient constituents was surveyed through a questionnaire as well as analytical observation. Taking the major environmental components of the paddy field into account, a mass-balance flow regarding fertilizing constituents such as nitrogen and phosphate was built up and used to estimate the contribution of fertilizer to paddy field water pollution. In the mass-flow analysis, the randomness of fertilizer used by local farmers is incorporated within the conventional input-output model. For the control volume of soil in 0-40 cm below paddy plot surface, the estimated average concentrations in soil were 1.8 ppm for inorganic nitrogen and 1.3 ppm for inorganic phosphate on the assumption of 50% non-excessive probability. From the reasonable consistency of the deduced concentrations of nutrients with observed ones, not only the mass balance of fertilizing substances but also the impacts of fertilizer on the paddy field aquatic environment in Vietnam could be understood. On the results from nutrient mass-balance analysis, it was found that 11.3-13.3 kg N/ha would percolate into the underground aquifer that is linked to surface channel flow in the vicinity of the paddy plots and affect the irrigation water quality. The nutrient portion in the materials harvested as grain and straw occupied 58% of total dosed nitrogen and 75.6% of total supplied phosphorous.