Currently in the drought evaluation, which is a supplier-oriented standard that applies storage rates of reservoirs, evaluation for users that use agricultural water is not done. Therefore, this study established drought evaluation items for drought evaluation based on farmers' judgement, conducted a survey on farmers and experts, compared and analyzed weighted value between two groups, and then classified the evaluation standards per each evaluation item. The agricultural drought evaluation items are 5 major items of water supply lapse rate, agricultural weather, agricultural irrigation facility, crop and soil, and 12 subsections for regional characteristics and opinions of consumers that use water to be reflected. The result of analyzing weighted value of farmers and experts' major items shows that farmers is agricultural irrigation facility(0.219), water supply lapse rate(0.211), agricultural weather(0.204), crop(0.183) and soil(0.183). Experts is agricultural weather(0.297), agricultural irrigation facility(0.202), water supply lapse rate(0.189), crop(0.162) and soil(0.150), which displays difference between the two groups. The agricultural drought criteria standards are established based on precedent studies and cases, and grades of evaluation items are 1st grade(extreme stage), 2nd grade(warning stage), 3rd grade(alert stage) and 4th grade(attention stage). The above analysis per each consumer-oriented agricultural drought evaluation item and the analysis on the standards of evaluation grades are expected to be used as a basic resource for establishing agriculture drought policy and selecting drought area in the future.
Salted-affected soil is a major environmental constraint with severe negative impacts on agricultural productivity and sustainability in reclaimed tidelands. This review focuses on the phytoremediation of reclaimed tidelands. We address the process of phytoremediation of these soils, comparison of phytoremediation with other amelioration approaches, driving forces contributing to the process, selection of phytoremediation crops, and the role of cropping in securing environmental integrity under salt-affected soils.
Accumulation of excessive salt in Reclaimed coastal tidelands can reduce crop yields, reduce the effectiveness of irrigation, degradation of soil structure, and affect other soil properties. These salts has shown to cause specific ions in the plant over a period of time leads to ion toxicity or ion imbalance and a continuous osmotic phase that prevents water uptake by plants due to osmotic pressure of saline soil solution. This review focuses on the characteristics of salt-affected soils, mechanisms of salt-tolerance plants, desalinization technology, and soil management to maintain sustainable agro-ecosystem in salt-affected soils.
It is the purpose of this study to investigate the change of stream water quality in upper stream of Dongjin river, and to give the basic information for the conservation of water quality. Water samples were taken periodically at 9 sampling sites during 8 months from March to October in 2002. The results of this study were as follows : 1. The water temperature and pH of stream water were ranged 9.0~29.4℃, 6.48~9.33, respectively. The COD values of stream water was ranged from 0.60 to 19.06. The contents of T-N and T-P mainly affected by the livestock wastes, and agricultural activity were 1.88~6.74 mg/L, ND(not deleted)~0.50 mg/L, respectively. 2. The SS, DO and BOD values of stream water were ranged 0.4mg/L~274.0mg/L, 0.5~6.0 mg/L, and 7.3~13.7 mg/L respectively. 3. The cation is one of the important components in analysis of stream water quality. The contents of analysis, Ca++, Mg++, Na+ and K+ were ranged 1.96~11.08 mg/L, 1.21~6.16 mg/L, 3.38~18.44 mg/L, 1.12~7.96 mg/L, respectively. SAR was ranged 0.31~1.63 below 2.0. The contents of cation showed in the order Na++>Ca++>K+>Mg+. 4. The contents of heavy metal Zn, Cu, and Pb were ND~0.071 mg/L, ND~0.012 mg/L, and ND~0.043 mg/L, respectively. Cd was not detected in all samples. 5. As a result of these researches showed water quality in upper stream watershed of Dongjin river more affected by livestock wastes and living sewage than agricultural activity.
The PTDRT model as prediction techniques for desalinization in reclaimed tidelands was developed and verified whether it is applicable to reclaimed tidelands at the beginning stage. The changes of salt concentration during desalinization, the water requirements and period required for desalinization, were simulated according to soil properties and desalinization methods by repression analyses. The program was also designed to systematize input data and analysis data associated with desalinization, and to confirm the results by a graphic form. All input data and the results can be printed after the form of a typical report.