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Rainwater harvesting in greenhouses

February 29, 2008
I visited China and was struck by the intelligent use of rainwater in Poly houses. Persuading a student to repeat the experiment here was the hard part and harder still was getting a lousy Rs 25,000/- to help Anil Kumar set up this experiment. TIDE came forward and helped the student. It is to the credit of Svati Bhogle and Chandankeri of TIDE that they have persisted with the idea and set up at least 3 more poly houses with the same idea. The are very excited about it and have written up a proposal and got funds for setting up 10 more 200 square metre poly houses. Now imagine there is a potential to integrate the small and marginal farmer with value added agriculture and improve his income dramatically and THIS IS A RAINFED POLYHOUSE. No bore well, no energy,no carbon emissions and IMAGINE again if we make it completely organic and use ECOSAN as fertiliser. What a gain? But who will help take this idea forward?Suppose we set it up on a fluoride affected area. Villagers can grow fluoride free crops and also take back 20 litres of Fluoride free water to drink every day. The same in Arsenic affected area.Will we rise to the occasion? Poly-houses for rainwater harvesting, an Indian and Chinese experience
 
S VISHWANATH discovers how sustainable poly houses possess the potential to solve the ongoing water problem in Karnataka.

Rainwater harvesting is the process of collecting and storing rainwater for future productive use.

Its role and significance are seeing a revival today owing to the enormous pressures on our limited water resources, depleting ground water levels. Apart from providing water security, the role of rooftop rainwater harvesting can also be in providing food security and growing value added crops.

China, for example, has pioneered the low cost poly-house model with rain water harvesting and drip irrigation to grow crops in a hostile terrain. In the Chinese model, poly-houses are built using a mud wall, mostly bamboo structural roofs coupled with steel and a plastic sheet for the roof. Since sources of water such as surface and ground water are simply not available, rainwater falling on the roof is collected and brought inside the poly-house where it is stored in an underground cellar.

 
 
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The water is then pumped by using a manual or electrical pump and a gravity-based drip irrigation system has been adopted to water the plants inside the poly-house. Excellent results have been reported with many crops, vegetables and flowers.

The State of Karnataka is the second largest drought prone state next only to Rajasthan. India as a whole suffers from drought at regular intervals. In such a situation it is imperative that answers be found for food security for our rural agricultural sector where more than 70 per cent of our population resides. Steps ahead lie in the introduction of these poly-houses for the growth of value added plants in a safe, controlled environment devoid of pests, where crops/vegetables/flowers can be grown in carefully monitored conditions. The floriculture industry has already adopted the poly-house technology.

Economical poly houses

Poly-houses however should be made of more economical, easy for assembling and efficient, so that it can reach more and more farmers.

With the introduction of drip irrigation, it is possible to reduce the amount of water used for the same. Water availability however is still an issue because groundwater levels are falling and there is high content of salts in the groundwater in many places. One solution in Karnataka also could be the systematic collection of rainwater falling on the rooftop of the poly-houses, storing them and using the drip irrigation system for the plants inside.

Preliminary work has suggested that the total water requirement for vegetables such as capsicum or flowers such as anthurium can be met through poly-house rooftop rainwater harvesting. For example, the rough annual demand for a 175 square metre poly-house is of the order of 52,000 litres.

The semi-annual demand for a crop of duration six months is 26,000 litres of water. In a place with an annual rainfall of 400 mm, the rainwater falling on the roof of the poly-house is of the order of 70,000 litres.

Assuming a collection efficiency of 80 per cent, 56,000 litres of rainwater can be harvested, which is more than the annual demand.

In theory at least, the poly-house becomes self sufficient for its annual water and power requirement. With the annual rainfall as low as 200 mm, a semi-annual crop can be cultivated.

This methodology has the potential of creating a substantial armoury of drought proofing our agriculture. Further research is needed in developing efficient systems of collecting rainwater without losses and low cost storage systems.

A student of GKVK, Shri Anil Kumar T D, studying in II year M Tech (soil and water conservation engineering ), is currently carrying out a research titled – Studies on Techno-economic feasibility of roof water harvesting system with greenhouse. It is being carried out under the guidance of Dr S B Batagurki, Associate Professor in the U A S Hebbal Extension Unit with assistance from Shri Krishna Manohar and Shri T N Tulasidas.

Such and future research will establish the applicability of the technology of rooftop rainwater harvesting for poly-houses in the Karnataka context which show an exciting potential.


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13 comments

  1. Excellent idea. The poly house using rain water and human and animal excrta is now a days very common site in China. Wherever you go in the country side and recently in the periphery of cities also you will find these polyhouses.We need to have a good reserch in Indian conditions since this approach has potential to integtrate four component of ecosan and truly becomes the productive sanitation. Urine, faeces,rain water and solid waste.I undertstand the saving in water from conventional irrigation to poly house with rain water would be substantial. Looking forward for concerte recommendation for particular type of crops using polyhouse with rainwater and using urine and faeces as fertilizer. All the best to Anil.


    • this is ecusamurai, if ur looking for crops using rain water & harvesting black water(sewage) into botanical cells with no carbon foot print, check out my friend michael reynolds at airship.com


  2. I wanted to know details reg construction cost (rate/unit vol or area)for a lowest cost polyhouse along with rainwater harvesting system,in reference to hill area (alt-5500-6000ft)of uttaranchal.kindly also inform me about govt subsidy if available.


  3. Hi
    I am interested in the construction of such an unit-
    can you please direct me to an appripriate source.
    Thanks
    sudipt


  4. we hahe a 8000 sq meter green house and a 3 lack ltr capisity tank. Iam planing to go for a rain water collection for the rose crop, I need finantional help, i need to know if any organization in karnataka giving subsidy for that,


  5. Hi,

    I am also interested in knowing about this rain water harvesting and ploy houses in uttranchal, dehradun.. please suggest an appropriate contact.


    • U all can contact me. i have carried out this research work. this video is from my research site.


      • you should check out earthship.com. thanks for doing the research ecosamurai@yahoo.com


    • U all can contact me. i have carried out this research work. this video is from my research site.
      Anilkumar. T .Dandekar
      New Delhi


    • if ur interested in rain water harvesting check out earthship.com. ecosamurai


  6. anil2sing@hotmail.com


  7. It is a useful information about drip irrigation. I am a farmer and we have very large fields, before drip
    irrigation system was found it was a nightmare to irrigate all those fields because where i live is a place
    that does not rain so much. Now we use drip irrigation, saving so many water and it is a lot easier to irrigate
    the field with that. I am trying to read everything about drip irrigation and i recommend every farmer to use that
    technique, so i am grateful for everyone who gives information about it. I also found a very good guide about drip
    irrigation and it may be useful too for those who want to learn more information about that;

    http://agricultureguide.org/



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