Farming, irrigation

Three kilograms of 1,000 g/m atrazine pesticide is accidentally dumped down an old farm irrigation well, placed to pump water out of porous sandstone. Estimate the movement of the atrazine plume over time and the concentrations in the plume. (See Figure E6.12.1.)... 

Fig. 16.4 Nitrate (dots) and chloride (circles) in groundwater of a well (no. 7) in a nonirrigated area, and wells (nos. 8 and 9) located in an irrigated area, Hancock Experimental Farm. Irrigation caused an increase in nitrate and chloride, caused by nitrogen and potassium fertilizers, the latter containing Cl (KC1). The quality of water was restored because of a decrease in farming activities. (From Saffinga and Keeney, 1977.)...

Roe, H.B. (1950). Moisture requirements in agriculture Farm irrigation. McGraw-Hill New York. 

Early in the century the amount of energy output in the form of food was about equal to the commercial energy input to the crop and livestock. That was before electricity, natural gas, and petroleum products were available to the farm. Now at least 10 kcal of commercial energy is used for each kcal of food energy produced. This change has occurred as a result of mechanization, irrigation, and consumer demand for low fat foods and for precooked and prepared foods. 

With a growing scarcity of freshwater available for irrigation, other sources of lower quality like brackish water, saline water, and treated wastewater become more important as additional or substituting inputs for the agricultural sector. At the same time, it is clear that a sophisticated treatment like desalination or nanofiltration under current conditions is still far too expensive to be a major solution to future irrigation water needs. Hence adaptation of farming and irrigation practices to the particular water qualities constitutes a more viable approach. 

Another important test location factor is the availability of water for irrigation and for preparation of the spray solution. The use of culinary water sources (either private or public water sources intended for human consumption) or groundwater (from wells) is usually less problematic than using water from surface sources (rivers, lakes, or canals). If surface water is used for the study, care must be taken to ensure that farm production activities upstream from the plot area have not contaminated the water supply with pesticides that could contaminate the plot area. Careful site selection will help avoid problems from the water available at the site. 

Organic agriculture aims to eliminate residues from production systems, rather than meeting maximum permissible values. Owing to the risks of contamination being introduced onto farms from external sources (e.g. with feed, via air pollution and/or irrigation water) and with greater accuracy of pollution measurement/detection systems, this aim appears to be more and more difficult to achieve. 

Water used for field irrigation is then transported to littoral lagoons, like in the case of the Badia d Alfacs, where important mussel farms are located (see Fig. 12). 

The system design is based on two upflow anaerobic bioreactors (ABRs) followed by three horizontal sub-surface flow (HSSF) wetlands cells. The water flows by gravity through the cells. Once treated, the water is stored in a holding pond and subsequently used for irrigation of a tree farm. 

Keywords Cultivation Fertilization Indicators Integrated pest management Irrigation Land conservation Organic farming Pest control Sustainable agriculture... 

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