Experience with gravity watering of fruit trees - using drippers and mini sprinklers

[dinga]

We are trying to resuscitate a small (about 3 rai) neglected orchard comprising a total of some 125 trees - growing in basically two discrete areas of 42 trees and 83 trees respectively.

 

The water will be supplied from a pond estimated to contain a useable quantity of about 1,000.000 litres.  It seems very unlikely that 1,000 cu metres of water will be sufficient for these trees if we used the usual watering method & equipment used in the orchards around us here in Rayong - hence I'm wondering about using alternate options for the 42 trees. 

 

I'm wondering about the viability of putting a tank at the top of the plot, pumping water from the pond into the tank (using a 2HP pump with a 2" outflow and a capacity of 36,000 litres per hour to an elevation of some 11 metres) and distributing the water to the 42 trees by gravity feed to drippers and mini sprinklers. 

 

Appreciate thoughts & experience of this idea which is aimed at being able to extend the available water supply for use over the whole dry season  -  in particular:

 

1.   It seems an 11 metre elevation will result in a gravity water pressure of over 15psi (1 Bar) - would that be sufficient for a sole main-line feeding all 42 trees or are two main lines (each for some 20 odd trees) likely required?

 

2.  Understand drippers and mini sprinklers are prone to clogging up - with water borne <deleted> and/or the like of ants/bugs etc.  Is this a real problem?  Does the frequency and/or extent of blocking make these a non viable option?

 

3.  Assume filtering the pond water at the pump is a must -- and likely at least filtered again on outflow from the tank.  Any suggestions about what filters should be used (is 120 mesh OK - I have one 3/4" one), how many and where should they be positioned? 

 

Greatly appreciate responses and suggestions to these and any other relevant matters.  

[carlyai]

I know a guy drip feeding his trees, but he's over in the UK at present and not on this forum.

Can you PM me and I'll try and give you his contact details?

[Elkski]

It seems you are aware of most of the issues.  I looked into this for the Thai family.  One concern by bro in law was having to clean silt out of the tank.  Most tanks don't have a hatch or big flushing drain so this becomes an ugly job at the minimum.  Filtering would help.  But even with them these spinner types wear out and you need replacement heads. 

 I don't understand how using a tank will extend your water capacity of the pond?

Some ponds are below the water table and fill in that way.  

Some micro spinner heads have a pretty big orifice so 120 mesh would work. But maybe their fkowrate is to high for 15 psi. It depends on what the local supplier keeps in stock and is used in your area.   Different spinners  don't last as long.    As for separating the trees into groups that may be needed depending on the flow rate and size and distance of the main line and number of trees.  Usually 2 heads per tree from what I saw being used on the durian trees. 

Some people use a solar panel and floating submersible pump to fill the tank and then gravity drip.  

Some design inputs needed are how much water will these trees need, how often is watering needed, and soil permability.  How dirty is the water?  You don't want to water to fast  for soil type or You get runoff away from the tree. To slow if a point dripper and you may not water the outlying roots.  

Also How far from the hammock is this? Having to open and close valves to water smaller groups of trees will be tedious and require more time onsite. Changing and cleaning filters, running the pump to keep the tank full. 

The main line can have distribution valves near the tree groups or multiple runs of the main line.  I think it's best to have the filter located where it gets more pressure so not just below the tank. 

Overall it's a complicated system, undependable and prone to problems and requires understanding of fluid dynamics.  

I tossed in the towel and we took the gas pump to the repair shop.  We also didn't have 11 meters without a tower. 

 

[dinga]

Thanks Elkski - interesting observations (yeah, I do wonder if all the implications just make it just too darn difficult).

 

As for the comment "don't understand how using a tank will extend your water capacity of the pond".  I will be raising the pond capacity by around 10% by increasing the height of the lowest bank (the geography prevents much else) but the thinking behind the gravity feed is to use less water than the typical butterfly sprinklers would on the smaller plot (while continuing to use them on the larger plot).  ie.  less water use for 33% of the trees should mean the pond supply will last for the whole Dry Season. 

 

Tks    

[farmerjo]

Who will be looking after it.

You mention we.

A 1000 litre IBC on a trailer(iron buffalo) and water can may work out more practical.

Stagger the watering.

Some trees might require more water than others.

 

[drtreelove]

I had a similar situation in Chiang Mai where my wife and I took over the 10 rai farm of a deceased horticulturist friend, with 3 rai of mature fruit trees,  73 longan and  55 mango.  We refurbished a bore well and tank tower, as well as pond pump water supply.  I went with bunds and flood irrigation where possible and hand held 1" hose watering where needed. 

 

I can't comment on the drip system you are asking about.  I am not in favor of drip emitters for trees.  As a tree care professional for over 50 years (mostly trees in landscapes and home orchards). And I grew up watching my father manage citrus orchards in the Arizona desert, with a very successful system of flood irrigation every 10 days. 

 

I have found that drip systems can keep trees alive, but is unnatural and not adequate for full absorbing root zone saturation, tree health and metabolic processes. One exception is well designed Netafim-type smart-drip soaker tubing systems. 

 

Infrequent deep watering is preferred. https://www.thespruce.com/watering-deeply-1402418

 

A lot can be done to improve and enhance soil moisture retention and water usage efficiency .  Soil aggregate structure is the key factor. This comes with building soil organic matter content, beneficial soil biology cultivation, especially AMF (arbuscular micorrhizal fungus) that produces glomalin which binds soil crumb structure and extends the absorbing capacity of tree root systems .  This is best achieved with Redox principles (reduction vs oxidation factors, including minimal tillage and avoidance of harsh chemical fertilizers, herbicides and pesticides) and photosynthate root exudates from mixed species cover cropping. Plus bio-inoculants. 

 

Matt Powers with Dr Olivier Husson on Redox

https://www.youtube.com/watch?v=LMACAg0ANCA

 

[Grafting Ken]

Hi as mentioned above Netafim do a great 8mm micro drip line and we used it for many years now both in our garden and now in our orchard. 
the dripline goes around the tree so gives a really good deep watering way better than any sprinkler. But we only grow a small variety of tree not huge fruit trees.

Pumping water from a pond into a tank I’m unsure if the water would eventually clog the drip line up.

think maybe disc filters rather than mesh or a mix of both would be better. 
you can contact Netafim direct on Facebook but I’ve found Plume also on Facebook have all the Netafim products and it’s all good quality gear much better than most you buy here… just on a note we water over 500 trees on our small orchard using the Netafim micro drip line.. it costs around 250 baht per month to water all.

[Elkski]

I began using netafim 17 years ago in my garden. I have used the 17mm with emitters every 12".  There are now other brands of 17mm and 12mm and emitter spacings of 6" and 18".  I  now use the 6" spacing because I have very sandy soil.  I grow raspberries with I think it is 6 rows of 12 mm spaced 6" apart so an emitter every 6" for a row 3' wide.   Water every day for about 25 mins. I have seen it used in circles around trees using a closed ring around the tree of maybe 4' diameter.  But mature trees would need a 2nd larger ring.    I have a 20 year old pinyon and juniper (40 survivors from 50) Forrest planted from seedlings that I supplied using 800' of 17mm netafim distribution tubing and then used 1/4" drip tubing with emitters every 12" .  The netafim warranty is only 10 years and I started having ruptured after 15 so  I removed it all 2 years ago. I did hand water the 4-6' tall trees 2 years ago 2 times but none this past summer.  I am hoping they are established as they are arid plants.   Totally different climate.  15 " rain / year.   I was using culinary water so no clogging issues.    

It you inherited trees it's hard to amend the soil.  You can put lots of mulch dressing which I have done.  I just used fertilizer spikes this past summer.  I rarely used any fertilizer before.  I probably should have.   

I say talk to many people.   Use the list of inputs, measure the water needs of your soil to get the penetration and spread you need.  Flooding the entire field may be ok when the trees are mature but wasting much water if they are young and spaced properly.   On other parts of my garden I am using 17mm distribution line and 1/4"  drip lines which I guess is 6mm.  I like the 6" spacing for my row crops.