Effect of SRI methods on water use,NPS pollution discharge,and GHG emission in Korean trials

Paddy and Water Environment - A field experiment with a locally-bred Japonica rice cultivar was conducted in 2011 to measure the effect of paddy irrigation management in Korea on rice yield, water...     

Strategies and engineering adaptions to disseminate SRI methods in large-scale irrigation systems in Eastern Indonesia

The system of rice intensification (SRI) developed in Madagascar has been controversial in part because there have been no large-scale, long-term evaluations of the impact of its alternative methods. This paper summarizes experience with the dissemination of SRI practices across eight provinces in Eastern Indonesia over nine seasons from 2002 to 2006 under a major irrigation project. The Decentralized Irrigation System Improvement Project (DISIMP) was financed by the Japanese Government with project management by a Nippon Koei consultant team. SRI has been introduced in Indonesia via several organizations and in different parts of the country starting in 2000. The evaluation reported here, made by the DISIMP technical assistance team, is based on data from 12,133 on-farm comparison trials that covered a total area of 9,429 ha. Under SRI management, average paddy yield increase was 3.3 t/ha (78%). This was achieved with about 40% reduction in water use, 50% reduction in chemical fertilizer applications, and 20% lower costs of production. The farmers whom DISIMP was assisting to take up SRI were usually cultivating their paddy fields individually within irrigation systems where it was difficult to reduce water applications as recommended for SRI. Accordingly, innovations had to be made in soil and water management to create relatively aerobic soil conditions so that farmers could get the more productive rice phenotypes expected from SRI practice. This article describes the modifications made to adapt SRI concepts, pointing to the value of introducing in-field ditches, which was confirmed through paddy tract surveys. This experience and analysis showed how SRI methods could be utilized within irrigation systems where water management was not (yet) tailored to SRI production practices. Subsequently, modifications in irrigation system management are being made to be more supportive of SRI cultivation.     

Effect of surface cover on the reduction of runoff and agricultural NPS pollution from upland fields

In this study, two types of simulations were performed. First, indoor rainfall simulation revealed that runoff ratio (0–63.3 %) decreased dramatically with surface cover, compared with no surface cover condition (55–85.3 %), and sediment load and concentration also decreased. With additions of PAM, sawdust, and rice hull to rice straw mat, the runoff ratio decreased to 52.8, 36.6, and 53.2 %, compared with only rice straw mat condition (runoff ratio of 63.3 %). When gypsum was added, no runoff was observed in case of rainfall intensity of 30 mm/h. Under 60 mm/h rainfall condition, 50 % or more runoff reduction was observed. These could be explained in that surface cover reduces detachment of soil particles and keeps infiltration rate by reducing surface sealing with detached soil particle which could happen under non-surface cover condition. Second, when rice straw mat was applied to soybean field, no runoff was observed until rainfall intensity of 5.8 mm/h or greater, while runoff was observed with rainfall intensity of 1.5 mm/h at no surface covered soybean field. In addition, 89.7–99.4 % of pollutant reductions were observed with rice straw mat at the soybean field. When rice straw mat with additions of wood shaves was applied to Chinese cabbage and radish fields, 4.3–75.8 % of runoff reductions and 28–80.8 % of pollutant reductions were observed. In case of Chinese cabbage, 122.1 % yield increase was observed and 153.4 % yield increase in case of radish.     

SRI as a methodology for raising crop and water productivity: productive adaptations in rice agronomy and irrigation water management

The System of Rice Intensification (SRI), developed in Madagascar almost 30 years ago, modifies certain practices for managing plants, soil, water, and nutrients with the effect of raising the productivity of the land, labor, and capital devoted to rice production. Certain production inputs are reduced—seeds, inorganic fertilizer, water, and fuel where water is pumped—with increased yield as a result. This paper introduces the subject of SRI, which is then addressed variously in the articles that follow. SRI is gaining interest and application in over 40 countries around the world. Its practices make soil conditions more aerobic and promote greater root growth, as well as larger, more diverse communities of beneficial soil biota. These below-ground changes support more productive phenotypes above-ground for practically all rice genotypes (cultivars) tested so far, with supportive evidence accumulating both from scientific institutions and field applications. SRI methodology remains controversial in some circles, however, because of the transformational change it introductions into traditional lowland rice production systems. This issue of PAWE brings together the results of formal research on SRI in a number of countries (Part I) and also reports on initiatives by government agencies, NGOs, universities, or the private sector, bringing knowledge of SRI to farmers in a wide range of agroecological circumstances (Part II). This introduction presents the basic principles that underlie SRI and discusses the nature of this innovation as well as considers some of the issues in contention. SRI continues to evolve and expand, being a work in progress. Its concepts and methods are being extended also to upland (rainfed) rice production, as well to other crops. Accordingly, SRI should not be regarded or evaluated in conventional terms as if it were a typical component technology. It is understood more appropriately in terms of a paradigm shift for rice production. In particular, it calls into question the long-standing belief that rice is best produced under continuously flooded conditions.     

Experimental evaluation of irrigation methods for soil desalinization

Paddy and Water Environment - Soil salinization has provided a serious threat for global agriculture throughout human history. It is becoming ever more prevalent as human land use intensifies in...     

Evaluation of on-farm irrigation scheduling methods for potatoes

The neutron probe, infrared thermometry and crop water stress index (CWSI), and a computer-assisted irrigation scheduling method were evaluated in terms of their effect on tuber yield, tuber quality, and water use. The experiment was conducted during 1990 and 1991 near Othello, central Washington, using Russet Burbank potatoes grown in a silt loam soil. Irrigation treatments did not commence until after tuber initiation. In general, no differences in total number of tubers and total tuber yield resulted from the different scheduling methods. However, the canopy temperature method showed reduction in the yield of number one tubers in 1990. The least total irrigation water was applied during the growing season with the neutron probe method. Using CWSI values above 0.5 to 1.0 (scale 0 to 10) for two consecutive days as a threshold to schedule irrigations appeared to be adequate for potatoes grown in silt loam soils. However, shortcomings of infrared thermometry suggested that this method may not be practical for scheduling irrigation of potatoes.     

The assessment of rill irrigation and perforated pipes for Lowland paddy rice under the system of rice intensification (SRI)

Paddy and Water Environment - Irrigated paddy rice needs new strategies and tools to improve water use efficiency and productivity by applying just enough to sustain production with huge savings on...     

Quantitative risk assessment for reclaimed wastewater irrigation on paddy rice field in Korea

Water shortage has become an important issue for Korean agriculture. Korea suffers from a limited agricultural water supply, and wastewater reuse has been recommended as an alternative solution. This study examined the concentrations of toxic heavy metals and Escherichia coli in a paddy rice field irrigated with reclaimed wastewater to evaluate the risk to farmers. Most epidemiological studies have been based on upland fields, and therefore may not be directly applicable to paddy fields. In this study, a Beta-Poisson model was used to estimate the microbial risk of pathogen ingestion. The risk value increased significantly after irrigation and precipitation. The results of the microbial risk assessment showed that risk values of groundwater and reclaimed wastewater irrigation were lower than the values of effluent directly from wastewater treatment plants. The monitoring results of heavy metals for each irrigated paddy fields did not show specific tendency. A risk assessment for toxic heavy metals was performed according to various exposure pathways; however, the results of the carcinogenic and noncarcinogenic risk estimation showed that the risk from reclaimed wastewater-irrigated paddy fields was the lowest.     

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.     

SRI技术本土化研究

水稻强化栽培技术体系(System of Rice Intensification,简称SRI)被认为是一种能够帮助水稻品种真正发挥其生物学潜力、遗传学潜力进而增产并节约生产成本,保障粮食安全,保护生态环境的一种栽培丁之术体系。但在我国不同生态地区应用有一个技术本土化的过程,以筛选适宜超级杂交稻组合为突破口,研究适宜栽插密度与方式、控制无效分蘖提高成穗率、人工除草与化除相结合、覆盖“旱润”高效节水灌溉、有机肥与无机肥结合的关键技术,并与不同季节茬口的适宜耕作技术有机结合,形成我国特色的水稻强化栽培技术体系．     

National risk assessment of irrigation on farmland near wastewater treatment plants in Korea

There are more than 130 agricultural water sources that are located near wastewater treatment plants (WWTPS) in Korea. The majority of the stream flow in these farmlands is dependent on effluent from the WWTPS during the dry season. This explains the indirect or direct reuse of effluent from WWTPs. Most of the farm workers use the effluent without any additional treatment because they have a lack of knowledge regarding water reuse. In addition, insufficient consideration is given to health and hygiene safety. This study reviewed the safety issues in these farmlands. A total of 53 farmlands located near WWTPs were investigated to determine if farm workers used effluent as irrigation water on their paddy rice fields. Total coliform, fecal coliform, Escherichia coli (E. coli), and the concentration of some heavy metals in paddy water and soils were measured. Quantitative microbial and toxic risk assessment methods were used to review the safety of wastewater irrigation. E. coli concentrations were used to estimate the microbial risk of enteric disease in the paddy fields. The microbial risk was 5.9 × 10^?4, which did not satisfy the minimum safety standards. Carcinogenic risk was 3.99 × 10^?5 and non-carcinogenic risk was 6.34 × 10^?1. These values were too high to be considered safe, even though the measurements of E. coli and some toxic metals were of short duration.     

仙居县水稻强化栽培技术（SRI）试验示范结果初报

水稻强化栽培技术是一种高产高效栽培方法。为探索SRI在仙居县的适用性和增产潜力,2003年我们在横溪镇下陈村建立了一个面积为6．67hm^2的杂交籼稻粤优938 SRI示范方,并在该示范方内和白塔镇高迁村设置了水稻强化栽培秧龄、移栽密度、氮化肥用量及品种对比等4项试验。示范方前作以绿肥为主。     

水稻强化栽培（SRI）对农业的增产增效和对环境的改善作用

水稻强化栽培是一种新型的栽培技术,具有明显增加产量和减少投入的作用．其推广应用对传统的农业生产产生了重要的影响。     

SRI及其在浙江的应用前景

一、SRI的基本含义与特征SRI,即水稻强化栽培体系 (SystemofRiceIntensifi cation),是1983年由Henridelaulanie神父在马达加斯加提出的一种水稻高产高效栽培法。SRI的基本观点是 :为使稻株产量更高 ,每株必须有更多的分蘖、更多的有效穗 ,每穗有更多的粒数、更大的籽粒。为了使     

寒地水稻不同灌溉方式下的群体素质比较试验

通过不同灌溉方式对比试验,研究寒地水稻群体素质变化。结果表明,采用间歇灌溉方式,水稻根系发育良好,可促进水稻分蘖及各生育期的叶片干重、地上部干重、千粒重等指标均在增长,提高稻谷产量6.4%。     

水稻强化栽培增产机理及其关键技术

2003—2004年在温州市开展了水稻强化栽培多点试验示范,强化栽培平均比常规栽培增产10.8%。早发优势明显、植株生长强健、每穗粒数多是强化栽培增产的基础。据此提出了强化栽培的主要技术措施。     

A review on microbial and toxic risk analysis procedure for reclaimed wastewater irrigation on paddy rice field proposed for South Korea

Water shortage has become a major agricultural concern, and “The Sustainable Water Resources Research Program” in Korea is currently addressing this problem through the development of treatment systems for reclaiming wastewater and the assessment of human health risks associated with its reuse. Through this program, started in 2001, many studies have examined various water resources. Reclaiming wastewater is one way to alleviate water-shortage pressures, and one of the major potential uses of reclaimed water is irrigation. However, the main concern with reusing reclaimed wastewater is the increased likelihood of human contact that might result in exposure to pathogens and increased health risks. Relatively few studies have examined the toxic risks using reclaimed wastewater for irrigation in rice paddy fields. This study provides an overview of methods for quantitative microbial risk assessment and toxic risk assessment of heavy metal concentrations developed in the previous studies that can be applied to the evaluation of rice paddy fields irrigated with reclaimed wastewater in South Korea.     

Effect on water quality in irrigation reservoir due to application reduction of nitrogen fertilizer

Until 1997, tea farmers in the Makinohara district of Shizuoka Prefecture, Japan, applied around 1.2 ton/ha of nitrogen fertilizer per year to their tea fields. In general, uptake amount of nitrogen by tea plants is around 300–350 kg/ha. Then some part of the remainder of nitrogen fertilizer leach into ground water and flow out into the river. The other part of remainder of nitrogen fertilizer is accumulated in the soil layer. Following a recommendation by the local government, this amount was then gradually decreased to 660 kg/ha in 1999 and 540 kg/ha in 2000. Although nitrate nitrogen concentrations in local ground and river water have decreased, they remain high today. The river water runs off from a watershed in the Makinohara area and enters a small irrigation reservoir called Tanno Reservoir, where it has caused deterioration of the water quality, that is, acidification of the reservoir. In Japan, environmental standard for nitrate nitrogen is 10 mg/L in public water body and ground water. Here, the author developed the Water Quality Tank Model, and applied this model to investigate the nitrate nitrogen concentrations in the rivers and an irrigation reservoir called Tanno. The author applies these findings to demonstrate that nitrogen concentrations continue to remain high due to nitrogen accumulation in the soil layer, and that the amount accumulated would be reduced by a reduction in application. The simulation results demonstrate a small decrease in accumulation in the soil layer, and thus that the present high nitrate nitrogen concentrations will continue in ground, river and reservoir water will decrease only gradually.     

不同耕灌方式对棉花出苗的影响

选取秋翻冬灌、冬灌春耕、春耕3种耕灌方式的条田进行棉花干播湿出试验,对其出苗、苗期长势、生长状况进行研究.结果表明,秋翻冬灌方式下干播湿出方式更有利于棉花出苗及生长,出苗率、株高、棉苗干物质质量积累量、大苗数显著高于其他2种方式.     

Comparative energy and economic analyses of conventional and System of Rice Intensification (SRI) methods of rice production in Thai Nguyen Province,Vietnam

The consumption of energy inputs in agricultural production has been increasing rapidly during the past decades. However, given the limitations and costs of non-renewable energy, increasing production while using the least energy possible has become a major concern of most nations. Prompted by this concern, we conducted a face-to-face survey of 90 farming households in Thai Nguyen Province, Vietnam, to find out how energy is being used in agriculture and, specifically, in their rice production. Through analysis of energy input–output balances, combined with economic efficiency analysis, a comparison was made of conventional and SRI methods of rice production. The study found that applying the SRI method can save around 23% of energy inputs, while increasing energy outputs by 11%. Economic benefits per hectare also rise by more than 8 million dong (USD 364) compared to those under the conventional cultivation system. The study also showed conflicts between the energy and economic balances for manual compared with machine ploughing operations. This study contributes to providing an overview of energy consumption in rice cultivation at the household level. Its findings can help stakeholders to assess current policies and make better decisions on the uses of energy in agricultural production. In addition, the comprehensive approach taken here to analysing energy use and efficiency could expand the analysis and comparison of energy uses at sectoral or activity level—still a new field in Vietnam and many other countries.