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ที่มา:วิทยาสารเกษตรศาสตร์ สาขา วิทยาศาสตร์

หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Sewage Irrigated Vegetable Production Systems around Hubli-Dharwad, Karnataka, India)

ผู้เขียน:ImgC.S.Hunshal, ImgS.R.Salakinkop, ImgR.M.Brook



Hubli-Dharwad twin city is the second largest urban area in Karnataka State, with a population of 800,000. Around 60 million litres of waste water are produced per day, none is treated. The waste water flows into natural courses, and along their routes farmers exploit this resource for irrigation of vegetables. The climate of Hubli-Dharwad is semi-arid (800 mm p.a.), so dry season cultivation of vegetables is a profitable enterprise. Apart from sewage water irrigation, dry season vegetable cultivation in this area is restricted to farms with borewells. However, these are expensive to install and the water table is subject to fluctuations in depth. The content of heavy metals in waste water in Hubli-Dharwad is minimal, due to the absence of heavy industry. Total suspended solids (110 mg/1) and solutes (780 mg/1) are high. Total N is 12.1 mg/1. The site studied consists of 40 ha irrigated by sewage. This is usually raised from the water course by electric pump to the head of the field, from where it is distributed through channels by gravity. Vegetable plots on individual holdings tend to be small, typically 0.6 to 0.8 ha, but intensive, with four or five crops being raised each year. In order of preference, main vegetables cultivated are Cauliflower (Brassica oleraceae var. botrytis), cucumber (Cucumis sativus), beetroot (Beta vulgaris), spinach beet (B. vulgaris var. bengalensis) and amaranthus (Amaranthus tricolor). Advantages for the farmer are increases of 25 to 50% in yield compared to crops grown with borewell irrigation, lower fertilizer inputs, protection from erratic rainfall conditions, and being able to take advantage of the three to five fold increases in vegetable market prices in the off-season. Disadvantages are increased prevalence of conjunctivitis and dermatological conditions, and greatly increased incidence of weeds and pests. The most problematic weeds are Portulaca oleraceae and Cyperus rotundus, which are removed by cultivation and hand pulling. The most serious pests are diamond back moth on brassicas and fruit borer (Helicoverpa armigera) on numerous crops. The pests exhibit resistance to a wide range of insecticides, and in serious years may render entire crops unsuitable for sale. Spraying with systemic organo-phosphates every week is often practiced, the farmer wearing no protective clothing. It is unlikely that this method of cultivation can be eradicated until full sewage treatment is installed. The challenge is how to minimise the most deleterious effects of this cropping system. For the consumer these include potential contamination by coliform bacteria and high pesticide residues. In addition the farmer faces high risk of pesticide poisoning. Potential ways forward are discussed.

Article Info
Agriculture and Natural Resources -- formerly Kasetsart Journal (Natural Science), Volume 032, Issue 5, Jan 98 - Dec 98, Page 1 - 8 |  PDF |  Page