Rain gun irrigation

Farm Questions
1

Sir
we were struggling to irrigate our sugarcane field because of water scarcity and also due to electricity related problems. I understood through my study from the internet that the best alternate tool for irrigation is the rain gun. Just a week back I purchased two rain guns and got them installed with our CRI open well pumps. I have used HDPE pipe (2" dia, 6kg/sqcm) with a tailor made stand to install the gun. Its performance is marvelous and it is saving water to a greater extent. I could irrigate 1 acre land within about 80 minutes. Now I am extending it for other possible crops like ground nut, beetroot, sweet potato etc. Please contact me if you want further help in this regard.
Jai kisan
R Vasudevan
jangalpur@yahoo.co.in
#09901515687

2

Dear Vasudevan,

Thanks for sharing this info. I think it would be most useful if you can provide more details on how you installed it, the field coverage, cost etc. Some pictures will be great too.

Regards,
Chandra

3

Dear Mr.Vasudevan,

Itis great and marvellous idea. You can give some more details to the benefits of the members.

K.SAINATHAN

4

Dear friends
I have attached some salient points about rain gun. Please go through it.

  1. What are all the crops in which Rain Gun can be used Sugarcane, Plantation crops such as coffee, tea, cardamom, etc., vegetables like Onion, cabbage, potato, cauliflower, carrot, beat root, tapioca, etc. and ground nut.
  2. What will be the time requirement for irrigating these crops
    It mainly depends on the effective root zone depth of the crops. For E.g. For sugarcane on an average a Rain Gun can irrigate nearly ½ acre in 1 to 1 ½ hours. Using Flood irrigation, farmers nearly take 4 hours to irrigate ½ acre of sugar cane. For onion and vegetable 45 minutes is enough to irrigate ½ acre.
  3. What is the H.P. required to operate our Rain Gun
    Minimum requirement is 5 HP. This even depends on the Kg/Sq. cm (KSC) the pump generates. Our standard minimum requirement is 2 KSC pressure. No motor/pump less than 5 HP will generate 2 KSC Pressure. So, our requirement is >5H.P upto 20 H.P. Better result can be obtained at KSC more than 2.75.
  4. What pressure will a 7.5 H.P. generate.
    It depends on many factors.
    a. The make of the pump, i.e. some pumps have low pressure but high discharge. This pump generates low pressure. Some Pumps generate high pressure with low discharge.
    b. Suction and delivery heads
    Suction head – distance from the pump to the foot valve.
    Delivery head – distance from the pump to the G.L.
    If the suction head is more than 40 feet, much of the energy of the pump is wasted in sucking water upto 40 feet. So this will reduce the outflow pressure of the water.
    Lesser the suction, higher will be the pressure. Open well submersible pumps have ‘O’ suction head. So, we may get high KSC pressure in these pumps.
    c. Conveying distance between the pump and the Rain Gun
    Larger the distance between the pump and the location of the Rain Gun, lesser will be the pressure due to frictional loss and conveyance loss.
  5. What types of pipes should be used for Rain Gun.
    The best choice would be HDPE, ‘QPC’ pipes, which can be assembled and dismantled easily. If the KSC of the pump is less than 2.75, Rain Gun can be operated in PVC pipelines of quality. If the pressure exceeds 2.75 HDPE pipes will be the only choice.
  6. What will be area covered by a Rain Gun.
    It again depends on the pump / motor. Higher the H.P., higher will be the KSC pressure. Higher the pressure, larger will be the throw distance.
    Larger the throw distance, larger will be area covered. For e.g. if the radius of the throw is say 80 feet,
    Area = 3.14 x 80 x 80 = 26,096 sq. ft.
    It is slightly more than ½ acre (1 acre = 45,600 sq. ft)
  7. How many Guns are required to irrigate say 10 acre of sugarcane.
    It depends on
    a. No. of water source the farmer has.
    If the farmer has 2 sources of water i.e. 2 wells or 2 bore wells, he can use 2 Rain Guns at different locations.
    b. H.P of the pump available
    If the farmer owns say a 10 or 15 HP motor, he can use 2 Rain Guns at a same time.
    c. Financial status of farmer.
    If the farmer is financially sound, he can purchase more than one i.e. he can install permanently one gun for ½ acre. So he need not shift each time after irrigating ½ acre.

CONCLUSION : A farmer with just one Rain Gun can irrigate upto 20 acres by shifting the Rain Gun periodically after irrigating ½ acre. For this the farmer has to install a main pipeline (PVC/H.D.P.E) with deliver provision per ½ acre. In this delivery provision he can install the Rain Gun periodically.
8. How will you irrigate the corner of the fields with Rain Gun
By installing the Rain Gun in one corner and by using the locking
system, we can irrigate the corners
9. What is the required height of the stand.
It depends on the type of crop. For Sugarcane and cardamom, 5’ height stand is required. For other vegetables, tea, coffee, ground nut, etc., 3’ to 4’ height stand is enough.
10.What is the advantage of Rain Gun over flood irrigation.
a. It saves more than 50% of the water used by flood irrigation.
b. It saves labour.
c. It saves electricity. In future if farm motors come under unit rating, Rain Gun will save nearly 75% of the electricity. Increases life of motor / pump.
d. As ½ acre could be irrigated within 1 ½ hours, the total extend of area irrigated per day nearly doubles. So, if a farmer cultivates 5 acre sugarcane with his available water and pump in flood irrigation, he can cultivate 10 acres of land by using Rain Gun with the very same availability of water and pump.
e. In flood irrigation, more than 75% of the water goes as percolation loss (say 25% of water is available at E.R.D). In any agriculture, the top soil is more fertile (for this only we apply fertilizers and manures). In flood irrigation, the fertility in top soil is washed away and goes as percolation loss i.e. the top soil is leached away. In Rain Gun irrigation as we irrigate only upto the E.R.D, there is no percolation loss or leaching.
f. Rain Gun Irrigation plays the role of Nitrogen fixation.
One of the major nutrient plant requires is Nitrogen. Atmospheric air contains 78% of nitrogen. As our Rain Gun resembles Rain, the water dissolves the nitrogen from air and gives it to soil, thereby adding nutritive value to soil. This is one of the reasons for increase in yield.
g. Reduces pest and insects attack:
Pests and insects get washed away during Rain Gun irrigation.
h. Uniformity in irrigation.
In flood irrigation, farmers usually open the delivery at one corner of the field and it goes to the next corner and entire field by gravity. In well-grown sugarcane fields, farmers are unable to go and inspect if the entire field gets uniformity in irrigation. If there is any undulation in the topography of the land, water may not reach to that part, where as in Rain Gun irrigation, the uniformity of the entire field is ensured.
i. Easier application of fertilizer and pesticides.
In well grown sugarcane, farmer feel very hard to spray in the interior field. In our Rain Gun, with a help of a fertilizer tank and a venture assembly, fertilizers and pesticides can be sprayed easily without any labour.
11.Advantages of Rain Gun over Drip Irrigation.
a. Less Cost
For one acre of Sugarcane installation of drip cost around Rs.24,000/-, whereas by using Rain Gun System, the cost comes round Rs.14,000/- only. If a farmer owns 10 acres of sugarcane if he is interested in drip, he has to install drip for the whole 10 acres at a cost of Rs.2,40,000/- where as if he use Rain gun, with a single Rain Gun he can irrigate 10 acres of land by shifting the gun properly. Drip irrigation cannot be shifted.
b. Clogging problem
In drip, the water oozes out through a small hole less than 1 mm, which gets clogged by the calcium carbonate and other chemicals available in water. So, after a period of one year most of the drippers get clogged. In Rain Gun, there is no clogging problem irrespective of the quality of water.
c. Easy intercultural operation
An intercultural operation in a drip field is a task, whereas it is easy in Rain Gun irrigation.
d. Less Maintenance.
raingun.doc (32 KB)

5

Thats very well said.

Mr Thorat
Engineer
Vedant Rainguns.

6

Thanks Vasudevan. I understand you have collected the information from here: servalsgroup.blogspot.com/2008/1 … l-and.html

In addition, it would be most interesting to post your practical considerations, how you went about it and some pics, of course.

Regards,
Chandra

7

Advantages:

Up to 2 acres coverage from one position - various model.
Convenient - No need to shift many small sprinkler.
Lesser length of supply pipes - saves cost & labour.
Micro climate through turbo drive - helps in best flowering.
Saves fertilisers and application cost - by foliar applications.
Can run on Tractor - Using much less Power.

Thanks
Thorat
Vedant Raingun

8

That’s right. I have purchased the rain guns From Servals. I thought the information may be useful to the society, that is why I have copied and pasted here. However I will furnish shortly the photographs depicting how it is being used in my farm.
Vasudevan R

9

Thanks for that. Yes, your practical info will be very interesting!

10

hi,
first i would like know whether with a disel pump[5hp] it is possible to irrigate with rain gun,second got a farm pond & the maximum distance will be around 100 mtr what will be chance if electric motor of 5 hp open well submersible is installed,thirdly if the stand hight is increased is it possible to irrigate a mango orchard of 1.5 acre,further i would like to know the cost of the rain gun & other accessories excluding the pipes. thanks susant panigrahi

11

Hello Mr Panigrahi
sub immersible pumps with 5HP capacity can have a thrust of minimum 2kg per cm sq; they have zero sucking head.
Diesel and open well pump of 5 HP can not support this. However, your pond well pump may support. Better to use 2" HDPE pipe. I paid Rs 6500 per rain gun. HDPE pipe costs about Rs105 per metre (I have used 6kg per cm sq). The stand may cost about Rs 1000, if you locally fabricate. Yes, mango grove also can be irrigated.
Regards
R Vasudevan

12

Hi All,

I’m a new member here. I liked the rain gun concept and would be willing to explore on a POC level.Are there are any rain gun delears in and around Hyderabad/Guntur, if so please let me know.

Thanks,

13

I have about 8 acres of land where I plan to plant Mango’s this year. I was hoping I could also grow groundnut.
Does rain gun damage young mango saplings ? What do you advice ?

14

No. But it may damage small crops.
Better use sprinkler to avoid heavy force and for better results.

15

Dear friends
I have been using two rain guns for my two 5 HP pumps. Rain gun irrigation is viable for sweet potato, sugarcane, groundnut etc. However for millets rain gun can be used prior to flowering stage. Yes, it is OK for mango plantation also. Water droplets from the rain gun is very small and gentle, they certainly do not harm the plants physically. If you adjust the flow and select the orifice properly that is enough. In fact I enjoy drenching whole day in it along with the crops. You please try sir.
R Vasudevan

16

What about intercropped plantations?For eg Mango with papaya or banana, how will you adjust the water requirements for different crops? I am planning tp plant mango(3 year old Alphonso with intercrop of short term crops like banana,papaya etc so will the raingun be a good choice for such a combination.What are the adjustments required for tree crops?
Regards,
Yaj.

17

Still Iam Advocating for sprinkler system to address all your requirements or crop patterns.

18

Can rain guns be used for irrigating maize crops. Are there any limitations in using rain guns like use before flowering etc.,

19

Dear Chandra, Just one small clrification: How much land levelling we need to do for irrigation with rain gun. I am intending to purchase farm land with gently rolling, undulating terrain.
Regards,
C. Siva Sankara Reddy

20

Hi Siva SAnkar,

Sorry I don’t know and will let vasudevan or any others respond.
My hunch however is that levelling would not be essential.

Chandra