Farming land was generally linked to excessive nutrients of surface water . Residential land use exerts a major effect on nutrients as well as alkali metals owing to animal and human excreta and the use of table salts, disinfectants, and food additives in daily life. Intensified fish breeding ponds posed serious threat to the surface water quality since a large portion of biogenic elements in the fodder was not utilized by fish. In addition,agri-chemicals like quick lime, calcium hypochlorite and potassium permanganate were used as disinfectants to prevent fish disease, which led to high levels of major metal cations .Many studies focus on the cycling of nutrients in ponds , whereas much less attention is paid to alkali metal and alkaline earth metal cations such as Ca2+, Mg2+, Na+ and K+. These metal cations are necessary to maintain the normal function of living organisms. For example,ebb flow table the ions of Mg2+ is involved in some enzyme-catalyzed reactions in the human body and also essential to chlorophyll synthesis in plants .

However, excessive contents of these cations in water bodies would have adverse impact on human health and ecosystem.For example, high levels of Na+ in soil tend to displace Ca2+ and Mg2+,which would reduce the soil permeability and consequently affect the growth and yield of crops .Ponds and reservoirs are widely distributed across southern China due to its abundant precipitation and agricultural demand,such as fish farming and paddy planting . To explore the impacts of land use and fish farming on the geo-chemical behaviors of alkali metals, we determined the concentrations of alkali metals of water bodies from 103 ponds under the influence of different land use and/or used for fish farming in southern China.The suitability of pond water for irrigation was finally assessed to the help farmers and policy-makers make related management strategies to better play valuable role of ponds. The head water watershed of Jinjing was selected as the study area in a hilly subtropical region of the Hunan Province, China. The annual precipitation in the study area ranges from 1200 to 1500 mm, and the elevation ranges from 56 m to 434.8 m.

The land use in the study area is dominated by three major types, namely forest, paddy fields, and tea plantations, which account for 58.5%,31.6%, and 4.3% of the total area, respectively. 5.6% of the remaining areas are waters and residential ones. In areas like this, agricultural products and aquaculture are generally the main sources of income for farmers. In the study area,there are approximately 2010 ponds with a density of 20 ponds per km2, and more than 60% of these are used for aquaculture . In our study, 103 ponds and reservoirs were randomly selected to observe the alkali metal contents of the pond water bodies. Quick lime and salt are commonly used as disinfectants in fishponds to prevent fish disease. Moreover, the feeding stuff is thought to be a major contributor to increase in nitrogen and phosphorus of fishponds.These kinds of fishing practice might affect the geo-chemical behavior of alkali metals. To study the influence of fishing practices on alkali elements, the correlation of alkali elements and different N and P components was presented in the context of forest land use with fish farming ponds vs. natural ponds.Precision farming aims to manage production inputs over many small management zones rather than on largezones. It is difficult to manage inputs at extremely fine scales, especially in the case of the tea irrigation system.

However, in real sense we expect site-specific irrigation approach to potentially improve the overall water management in comparison to irrigated farms of hundreds of acres. A critical element of the irrigation scheduling and management is the accurate estimation of irrigation supplies and its proper allocation for the irrigation of structures based on the actual planted areas. All irrigation scheduling procedures consist of monitoring indicators that determine the need for irrigation. The final decision depends on the irrigation criterion, strategy and goal.The amount of water applied is determined by using a criterion to determine irrigation need and a strategy to prescribe how much water to apply in any situation. The right amount of daily irrigation supply and monitoring at the right time within the discrete irrigation unit is essential to improve the irrigation water management of a scheme .Many computerized tools have been used for scheduling irrigation deliveries and improving the irrigation project management. One such tool is a Geographical Information System.Its use in irrigation management with their large volumes of spatially and temporally distributed data is most beneficial. The GIS capability to integrate spatial data from different sources, with diverse formats, structures, projections or resolution levels,constitute the main characteristics of these systems, thus providing needed aid for those models that incorporate information in which spatial data has a relevant role. This explained about the capability of GIS for decision-making.