跳至主要内容

Characteristics of Drainage Water Quality and Loading from Paddy Field under Cyclic Irrigation and Its Management Options

In Japan, the cyclic irrigation system is encouraged through the national subsidy for system installation and pump operation and has been practiced for reducing pollutant outflow loadings from paddy fields. The cyclic irrigation pumps drainage water and reuses it as irrigation water to the farmland. Quantification and assessment of the effects of the cyclic irrigation are needed to identify management options for maximizing the benefits of cyclic irrigation. The study was aimed at assessing loading characteristics from paddy field area under the cyclic irrigation and developing a model for simulating water and material flow in paddy field area that can be used as a management tool.

The study was carried out in a paddy field in the Asagoi District, Oumihatiman city in Shiga Prefecture, Japan. The field data were collected from April 2010 to September 2012. And during the monitoring period, four sampling points were set up; three in the main drainage canal and one at the Biwa Lake Pumping Station. The automatic water level sensors were installed at each sampling point in main drainage canal. And during the normal irrigation period, water samplings and flow measurements were conducted once every two weeks; during the land preparation period, samplings and measurements were carried out every day owing to the high amount of drainage loadings and variations of water quality/quantity. The concentrations of total nitrogen (T-N) and total phosphorus (T-P) were analyzed by using the Absorption Spectrophotometry method. In addition, cyclic irrigation model was developed using System Dynamics Model (Vensim Professional).

The result indicated a higher nutrient absorption rate in the cyclic irrigation site than that in the non-cyclic irrigation site. The developed cyclic irrigation model showed good agreements between observed and simulated drainage volumes and nitrogen loadings. The scenario analysis by application of the model showed a potential of reducing the loading amount by increasing the cyclic irrigation ratio and reducing the amount of fertilizer application without affecting the rice yield.

Article by Nobumasa Hatcho, et al, from Japan.

Full access: http://mrw.so/1OLPQv
Image by Prakash Shankaran, from Flickr-cc.

评论

发表评论

此博客中的热门博文

Incorporation of High-Altitude Balloon Experiment in High School Science Classrooms

High-altitude balloon is a balloon, filled usually with helium or hydrogen that ascends into an area called “near space” or stratosphere. The most common type of high-altitude balloons are weather balloons. Other purposes include use as a platform for experiments in the upper atmosphere. Modern balloons generally contain electronic equipment such as radio transmitters, cameras, or satellite navigation systems, such as GPS receivers. The mission of the High-Altitude Balloon Experiment (HABE) is to acquire supporting data, validate enabling technologies, and resolve critical acquisition, tracking, and pointing (ATP) and fire control issues in support of future space-based precision pointing experiments. The use of high-altitude balloons offers a relatively low-cost, low-vibration test platform, a recoverable and reusable payload, worldwide launch capability, and a 'near- space' emulation of the future space systems operational scenarios. More recently, several university...
1 条评论
阅读全文

Effects of Karate Training on Basic Motor Abilities of Primary School Children

“You never attack first in karate” might be the best conclusion of karate, which is a martial art practiced typically without weapons. It’s reported that karate has a long history for several hundred years, but the modern karate was spread to the whole Japan from Okinawa in the early part of 20th century. Now it has become one of the most widely practiced martial art forms in the world. Usually, it’s divided into Kihon, Kata and Kumite. As for the beginners, Kihon is more suitable for them because it involves basic techniques. Due to karate consists of dynamic offensive and defensive techniques using all parts of the body to their maximum advantage, the best understanding of true karate practice is the perfection of oneself through the perfection of the art. It not only develops coordination, quickens reflexes, and builds stamina, but also develops composure, a clearer thought process, deeper insight into one’s mental capabilities, and more self-confidence. So many researchers stu...
发表评论
阅读全文

Electron Spin and Proton Spin in the Hydrogen and Hydrogen-Like Atomic Systems

Read full paper at: http://www.scirp.org/journal/PaperInformation.aspx?PaperID=52202#.VIj7tMnQrzE Author(s) Stanisław Olszewski * Affiliation(s) Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland . ABSTRACT The mechanical angular momentum and magnetic moment of the electron and proton spin have been calculated semiclassically with the aid of the uncertainty principle for energy and time. The spin effects of both kinds of the elementary particles can be expressed in terms of similar formulae. The quantization of the spin motion has been done on the basis of the old quantum theory. It gives a quantum number n = 1/2 as the index of the spin state acceptable for both the electron and proton ...
发表评论
阅读全文