Comparison of efficiencies and costs of different weed control methods in paddy production in Iran

Using of efficient and inexpensive method for weed control has an important role in increasing efficiency and reducing costs of production.In this study,field experiments were carried out to evaluate the efficiency and costs of several weed control methods in paddy production during summer in Mazandaran,the north province of Iran in 2011.Seven weed control treatments(T1 to T7)were applied at three stages of rice growth(20 and 35 days after transplanting and grain harvesting time).Weed density,weed dry weight,labor used and economical comparison were determined in the basis of a complete randomized block design with three replications.Results showed that there were no significant differences among efficiencies of six treatments(except for weedy check method(T6)treatment).The minimum weed density and dry weight were obtained at herbicide+hand weeding once(T5)and herbicide application once(T7)treatments during all three stages.The costs of weed control were different among the treatments.Selection of control method has an important role in reducing labor.Hand weeding twice method(T1),because of its high weeding cost,hard work and worker restriction in the required time,is not useful.Powered weeding twice method(T2),due to its zero environment pollution,reducing costs of weed control and high benefit/cost,is the best and most appropriate treatment.Amount of weed damage in weedy check method(T6)varied between 30.5%and 45.3%.

Climate Change Impact and Its Contribution Share to Paddy Rice Production in Jiangxi, China

In the study, an improved approach was proposed to identify the contribution shares of three group factors that are climate, technology and input, social economic factors by which the grain production is shaped. In order to calibrate the method, Jiangxi Province, one of the main paddy rice producers in China was taken as an example. Based on 50 years （1961-2010） meteorological and statistic data, using GIS and statistical analysis tools, the three group factors that in certain extent impact China＇s paddy rice production have been analyzed quantitatively. The individual and interactive contribution shares of each factor group have been identiifed via eta square （η2）. In the paper, two group ordinary leasr square （OLS） models, paddy models and climate models, have been constructed for further analysis. Each model group consists of seven models, one full model and six partial models. The results of paddy models show that climate factors individually and interactively contribute 11.42-15.25%explanatory power to the variation of paddy rice production in the studied province. Technology and input factors contribute 16.17%individually and another 8.46%interactively together with climate factors, totally contributing about 25%. Social economic factors contribute about 7%of which 4.65%is individual contribution and 2.49%is interactive contribution together with climate factors. The three factor groups individually contribute about 23%and interactively contribute additional 41%to paddy rice production. In addition every two of the three factor groups also function interactively and contribute about 22%. Among the three factor groups, technology and input are the most important factors to paddy rice production. The results of climate models support the results of paddy models, and display that solar radiation （indicated by sunshine hour variable） is the dominate climate factor for paddy rice production.

Multiple cropping and soil fertility in sustainable production of paddy fields

Multiple cropping has been popularized on morethan two thirds of the total area of paddy fields inSouth China.It demands more nutrients due tohigher cropping index.Therefore,how to keepmoderately higher yields of multiple crops and to

Changes in Organic Carbon and Nutrient Contents of Highly Productive Paddy Soils in Yujiang County of Jiangxi Province,China and Their Environmental Application

Paddy field is an important land use in subtropical China. Development of high soil fertility and productivity is the management goal of paddy field, Fertilization and management practices have not only influenced the status of organic matter and nutrients in the soil but also affected the environmental quality. This article investigates the contents of organic carbon and the nutrients, and the change over the last 20 years in highly productive paddy soils and their environmental application. Field soils were sampled and the analytical results were compared with the corresponding values in the Second Soil Survey in Yujiang County of Jiangxi Province, China. The results showed that surface soils at a depth of 0-10 cm in highly productive paddy fields in Yujiang County of Jiangxi Province had contents of organic carbon （20.2 ±3.88） g kg^-1, total nitrogen （2.09±0.55） g kg^-1, and available phosphorus （42.7 ±32.7） mg kg^-1, respectively, which were all at very rich levels. Over the last 20 years, the organic carbon pool of the highly productive paddy soils reached a steady state. Total N and available P significantly increased, whereas available K changed a little. The amount and percentage of P immobilization in the surface soil （0-10 cm） of highly productive paddy fields were （142.7 ~ 41.1） mg kg-~ and （36.2~ 10.4）% of added P, and CEC （7.93 ~ 1.32） cmol kg-~. These two parameters were not higher than the mean values of paddy soils and upland red soils in the areas. Results also showed that fertilizer P in highly productive paddy soils had a high mobility and was prone to move toward a water body, which is the main source of nutrients causing eutrophication. Because of a weak K-fixing capacity, the available K content was not high in highly productive paddy soils. This suggests that attention should be paid to the K balance and the increase of soil K pool.

WebPIPA （Web Based Paddy Irrigation Productivity Assessment）： An Online Irrigation Water Supply Management for Tanjung Karang Rice Irrigation Scheme （TAKRIS）

Irrigation water management has significant economic implications in developing countries like Malaysia. As in many countries, Malaysia is also espousing internet as a platform of new possibilities for information access and sharing. Thus web based decision tools are pertinent in managing water, which is becoming a source of conflict between domestic, industry and agricultural use in this emerging technological and information age. Decision Support System （DSS） created in the past was theoretically acceptable but practically not effective in the transfer of scientific knowledge from research labs to the end-users to support them in decision making. The Web Based Paddy Irrigation Productivity Assessment （WebPIPA） is an example of DSS created to provide an effective conduit for the transfer of scientific knowledge from research labs to the end-users to support them in decision making. WebPIPA serves as an innovative, user friendly and efficient management tool for run-of-river rice irrigation system. It is a web based program that requires users to login through user name and password WebPIPA is developed using Net framework and ASP. Net Programming Languages of Microsoft. Net 2003 environment. A 3-tier architecture framework was carefully studied and was implemented to create the WebP1PA model. Mathematical model developed for aiding irrigation decisions must be oriented towards addressing various issues in addition to the scientific ones for better acceptability. All government and private agencies, researchers, station users, farmers, investors and buyers related to this study area will be able to access and share the database through the internet. By strengthening the involvement of government departments, the database can be very effectively used by all stakeholders at the same time narrowing the gap between the urban and rural communities in the development of country.