Drip Tape Irrigation

[JackE]

Thanks Steve. Dunno what I'd do withoutcha.

Jack

[JackE]

Steve - if your still monitoring the thread -- or other knowledgeable individuals LOL.

Do you use vacuum relief valves to keep dirt particles from siphoning back into the system when it shuts off? If I bury the tape in this fine sand, I think that might be a problem. I found the valves at the Drip Store but not much instructions - just says install at "high points."
Do I need one at every row valve or just one at the highest point, which is the main supply line at the well?

Without the valves does it actually plug the emitters and ruin the tape for good, or will it blow the emitters clean when it starts-up again? In which case, I could just open the end of each row now and then and flush water through it? This is complicated by the fact that I made my main zone too big and the well doesn't keep-up. The pressure pump goes on and off frequently while the compressor catches-up - which would preclude a manually operated relief valve.


Jack

[Heritage]

Jack,

I don't understand the physics behind the reason for using a vacuum relief valve, but I do use one upstream of my fertilizer injector just because it said to, in the installation instructions - to keep fertilizer from flowing back into the house water supply. They also recommend them if you bury the tape.

I would guess you would need one wherever you use a valve to shut off the flow of water. But I have no clue why. I shut off my water at the injector, so only use one vacuum relief valve.

Sorry I can't be more help, let me know what you find out. I've always been curious as to how the tape can suck air (and dirt) when the valve is off.

Steve

[JackE]

I've always been curious as to how the tape can suck air (and dirt) when the valve is off.

Yeah - seems like there's no place for the air to go, I'll put one in the main supply line near the shut off valve just to be on the safe side. The 1/2" ball valves at every row in each zone won't need to ever be shut off (guess I didn't really need to put them in there!)

This well is completly separate from the house well so I don't have to worry about back-siphon - wouldn't hurt a thing.

Thanks again, Steve

Jack

[JackE]

We are now cultivating the greens planted along the new drip tape for the first time. It's not going too well. The tape is all curvy, which Steve has explained, making it very difficult, if not impossible, to keep the cultivator tines away from the tape.

We normally cultivate each side of the rows with a mini-tiller, followed by another person with a wheel hoe. It's a good system, but we're gonna have to find a way to keep that drip tape in place - in a straight line. Maybe bury it shallow REAL close to the row, so the cultivator operator knows exactly where it is at all times.

We're also going to have to be much more precise with the planter - use the row marker on the planter, run a string on the first row and keep it straight. I've never bothered with that - I thought is was just for looks!

If it would just RAIN, I wouldn't have to be fooling with any of this.

Jack

[Heritage]

Jack, for row flowers most of the growers here pull the drip tape to one side (like 2' away) and then lay it back after cultivation - it only takes about a minute per row. But, the cultivation here is by hand (hoe) so not sure that method would work for you. Usually, the second cultivation (when the plants are about 6" tall) buries the tape next to the plants in the process. Sometimes, depending on the crop, this burying is incorporated into the first cultivation.

I've never plugged plants into plastic mulch but for the larger plants (like tomatoes) this might be the answer to many of the drip tape idiosyncrasies.

Keep us updated,
Steve

[JackE]

Thanks again, Steve,
[I know that you already know all this stuff - I'm writing the following for other growers who may also be drip tape beginners]

One of our volunteer ladies did just that this morning - disconnected the tape at the valve and simply moved the tapes aside and, with one person at each end, quickly put them back when finished. The tapes are now lying right next to the little plants, within the 'lay-by" mounds created by the wheel hoe. The plants will soon be big enough to not be damaged by the contortions of the tape - there may be a little minor damage if the tape actually covers the seedlings, but I think think the cultivation problem is solved.

I have one zone of 400' of permanent trellis where we will plant Sugar Snap peas pretty soon. I had some pressure regulation problems there - blew it apart a few times trying to drop the pressure by opening valves in the other zones. I finally installed a 12# preset pressure regulator and that worked. I found that I shouldn't open more than one zone at a time, so I'm going to add more lines to the trellis zone to accomodate full flow from the well. The well tank is overflowing with only 400' of line running (we have a float valve on the pump but the compressor runs all the time).

The trellis zone is is a long way, and slightly uphill, from the well and I can't have the pump turning on and off, because, despite a check valve in the 2" supply line, the water leaks out and when the pump restarts it takes too long to fill the line again. I guess the check valve is leaking. On that zone, I need to get just the right amount of water flow to keep the pump going without overflowing the tank (wasted electricity).

I also added vacuum relief valves at all zones. Thinking about our conversation re the physics of siphoning, I removed the top of one valve after I shut off the water and it was indeed "sucking air" just like they warn. So I guess it would suck dirt too.

I'm really impressed on how much we can actually irrigate with this little well, using drip tape! Seems like I can theoretically have enough zones to do the whole three acres just by changing valves every couple of hours. If it ever rains and our pond refills, I will pump the lake water into the well storage tank, install a larger pump and have unlimited water ( the lake pump delivers 60GPM - which we needed with our primitive system of sprinklers and flooding).

Jack

[JackE]

Re: Plasticulture

This is a step we should take, to be sure - especially with tomatoes. We tried laying it by hand once and I don't want to do that again - I want it hilled-up and stretched tight! We've been talking about a mulch layer for some time and would probably have bought one by now were it not for the drought. We have had almost no revenues this year - just a meager tom harvest in May. I'm doing all this irrigation work out of my own pocket (it's fixed infrastructure on my property), but I'll let the Gardeners for Jesus project buy the mulch layer.

Jack

[Heritage]

Jack,

That is interesting - you have more variables to deal with than I do, since I'm on a set pressure and unlimited (except for pipe size) flow. I think coordinating a storage tank, pump, and compressor to supply water would be an interesting challenge - but one I'm happy to do without.

With your 400' foot trellis it must nice to have TOO much water for a change - probably not something anyone in Texas has had a problem with recently.

Steve

[JackE]

Where I live, the nearest community water source is 8 miles away in Woodville - but I don't envy them. They pay outrageous prices for it - so high that a lot of folks in town can't afford to water a garden. The only utility service we have is electricity and phone (old copper wires from the 1950's that won't carry the internet - we have to use satellite internet - and no bars for the cell phone. We can walk 1/2 mile out to the county road and get two bars. No tv cable either. Satellites have been a real blessing for us.)

Jack

[JackE]

We've been doing some experimentation today with burying the tape directly beneath the crop row in order to facilitate cultivation/weed control. A review of the literature indicates that subsurface placement in-row, with the depth determined by soil conditions and the crop itself, is widely practiced.

First we made sure we had a perfectly flat and clean seed bed. We then ran a string between stakes at each end of the 100' row and carefully drew a line with the hoe handle directly under the string for guidance, removed the string and made a 4" furrow with a narrow blade on the wheel hoe. We then layed the tape flat and straight in the furrow with each end lined-up with the stakes, and covered it by hand with a hoe. We ran the string again to make sure we were directly over the tape, made another line in the soil to guide the front wheel on the Earthway planter, and planted the row with turnip greens.

We'll water this row by hand until the seed germinates. If we didn't mess-up, the seedling line should be precisely over the tape and hopefully we can cultivate with the tiller as usual without hitting the tape. We had a long discussion over whether to bury the tape at 2" or 4". I wanted to bury it at 4" and, since I'm the boss, that's what we did.


The chief climatologist at TX A&M says that this drought will last for several years - that another La Nin~a is already forming in the Pacific, which assures a repeat of this horrible year! There was a bad drought here in the late fifties and he says that present oceanic patterns are almost indentical to that time with, he added, considerably higher carbon content in the atmosphere (read: global warming) which is an aggravating factor.

Jack

[moon1234]

Don't believe the global warming hype. One volcano erupting is the equivalent of 100 years of mans attempt to do anything.

As for drip, I would suggest dealing with Irrigation Mart in LA (The state). They are cheaper than almost everyone else and will help you properly design a system.

I inject 80% of my fertilizer. I grow melons in WI and I get by with less than half of the conventional recommendations. I use a cheaper injector called an EZ-FLO injector. It is nowhere near as accurate as a dosatron, but the plus side is I just dump in a whole bag of dry, pilled fertilizer and it continuously adds water. This works because only so much fertilizer will dissolve in water. Once that saturation point is reached you max the max concentration. As water flows into and out of the tank this mix is kept at a fairly consistent rate until the tank is near empty.

Why don't I care about being real accurate? I inject a weeks worth of fertilizer in one irrigation cycle. This means that it is more concentrated over the whole field at the beginning and less concentrated at the end. As long as you push out the whole amount in one irrigation cycle, you won't have inconsistent fertilization.

EZ-Flo's are really cheap as well. $80 for a 3 gallon. $250 bucks for one that holds a 25lb bag, etc. You don't need to premix in a 50 gallon drum, etc. I like just taking the cap off, dumping in the whole bag, putting the cap back on and i'm done until next week. Been working a treat for me for the last few years.

Keep in mind that if you need to irrigate a larger area, you can go with lower flow tape, you just need to run your cycles for a longer amount of time. We do a full acre of melons at a time on a 1" LDPE header line. We are putting in a 2" line this coming year.

You mentioned a mulch layer. I have the rain-flo 345, which is a flat bed layer. Got it on craigslist for $500. It lays the drip tape and mulch in one shot. It is a HUGE time saver. Keep in mind you need to REMOVE the mulch and tape at season's end. I used BioTelo this year. It is Biodegradable mulch. I just pull up the drip tape and wind it on a spool. The mulch is disced in and then the field plowed. You won't be able to find any trace of the mulch by next spring. Costs about three times what normal plastic mulch does, but well worth it.

You should ALWAYS have a pressure regulator and at least 150 mesh (200 is better) screen filter installed. They will NOT slow down water flow or pressure if properly installed. Sand can clog the emitters on the drip tape and you won't know it is a problem until it is too late.

Here are some youtube videos that will be visual aids:
http://www.youtube.com/watch?v=ER5EnuUYe-s

http://www.youtube.com/watch?NR=1&v=h2vUKbmZQHU

Here is how MOST people transplant through plastic:
http://www.youtube.com/watch?v=tWXrDLe6z8k

Grab Toro's Ag Drip Irrigation owners manual:
http://www.toro.com/en-us/Agricultur...rs-manual.aspx

That should tell you 90% of what you need to know.

And finally, here is irrigation mart:
http://www.irrigation-mart.com/html/products.html

Ask for Robin. He is the agronomist there and knows more than you will ever need to know about drip and designing a system.

IF you do drip correctly with fertilization, you can MORE than double your yield. This year I pulled 2000lbs of cherry tomatoes off of 90 plants. Yes you read that correctly. No one believed me until I showed them.

I also sold around $4000 dollars of melons off a little over 1/3 of an acre. Yes you read that correctly.

Just remember that header lines and sub mains should be sized properly. The longer the distance to the well the larger the diameter of the pipe or you will have friction loss and it can add up quickly in small diameter hoses.

Pressure regulators should be right near the sub-mains (the lines your drip tape hooks up to). 12 PSI is what I use for my regulators.

The ends of your sub mains should also have auto-flush caps on them as well. These are special caps that have a valve in them that opens when the water pressure drops to about 2psi. This allows the water to flush out the ends, along with any sediment. It also allows air in so that any water that is at a lower elevation and is draining does not cause sand or dirt to get sucked into drip tape higher up in elevation.

ALWAYS put in a vacuum breaker on your supply line if you are injecting fertilizer. If you don't have proper venting on your drip system it is possible to suck fertilizer back into your house if the pressure in your house drops while you are irrigating or if there is vacuum in the drip system. These costs a few bucks and are well worth the investment.

[JackE]

I can't thank you enough for all that invaluable info! It answers most of the questions I still have - but my feeble brain is still coudy on how the injector regulates the fertilizer.

I didn't know about the flush caps - I'll get some. I do have the vacuum release valves, one for each zone, and 12# pressure regulators as well. I have a large 200 micron filter on the main supply line at the well, but right now I have the element removed - it is a disc type filter and I didn't feel it was letting enough water through . I'll put the element back and try it again.

The well is completely isolated from our house well, so feedback is not an issue. The water is very clean except for sand. I have a sand trap at the tank itself, along with a flush valve, and it seems to be catching all the sand - I haven't seen any sand in the bottom of the filter cannister.

I still haven't bought an injector - still applying the fertilizer(Peters 20-10-20 liquid in 25# bags) with the sprayer. I fertilize weekly at the rate of 1# per 400 ft of row for row crops and 1# per 100 plants for tomatoes. I also add calcium nitrate every other week to keep the pH up.

I'm still not very clear on the injection operation, but I'm learning from study. If I buy that larger EZ-Flow, and dump a 25# bag of fertilizer in it, how do I know how much is getting to the plants? Wouldn't it dump a very strong mixture at first and then get weaker and weaker? I don't understand how to control the rate of application. I'm going to study your links - maybe I can get it into my head how this works! I'll hold-off installing one until I understand how to use it.

You made a great deal on that mulch layer. We're looking for one. But used ones are always so far away!

Thanks again. What's your first name?

Jack

[JackE]

Moon --

I called Irrigation Mart once to get some silver plastic when we had TSWV problems with the tomatoes (the reflected light was supposed to deter the thrip). Frankly, I didn't find them all that helpful. They were very busy and real short and curt with me. I got the impresion they aren't much interested in small growers like us. I'm dealing with Dripworks in Calif on this project.

I waded through the Toro instructions (very hi-tech). Is the following right?

The injector installs in the main line on the garden side of the 12# regulator (NOT the high pressure side, right?)

Clear tubing will show me if fertilizer is flowing. It will be blue color in the line out of the injector. When it flows clear, the fertilizer will be done? With the sprayer, I mix 100 gals at a time and have complete control over how much I'm applying per foot of row by regulating tractor speed. But that injector would save us a lot of labor and $4 diesel fuel.

So, if I want to apply 1/4# of soluble fertilizer to each of 12 100' lines in a zone, I put 3# of dry 20-10-20 in the injector tank and run the water until it flows clear. There appears to be settings on the injector - what setting would I use?

I guess what's baffling me on this is how to make sure it's going on the crop uniformly. My wife uses a hose end, suction-type applicator to fertilize her flowers. She puts a pound of Miracle-Gro in it and it comes-out way too strong (real DARK blue) at first and then gradually weakens - no uniformity at all! I'm worried this injector is going to behave like that thing!

Jack

PS - Do you have problems with the soluble fertilizer getting real hard in the bag? We buy a large order once a year to get a good price and within a few months it's hard as a rock - we have to put it in a big tub and beat it with a sledge hammer! This is a very humid climate. We used to use Peters 20-20-20 and it didn't harden as quickly as the 20-10-20 does. We switched to the lower P formula because it was $10 a bag cheaper. There is a worldwide shortage of Phosphorous and it's gone through the roof.

[moon1234]

I have never had a problem with irrigation mart. I do spend around $800 a year with them though. Still don't think that is very much.

Every University trial I have seen says the reflective much does nothing to repel any bugs. Waste of money, environmentally irresponsible and the reflections ohh my.

I install my injector right after the valve and before the screen filter. It would be the High Pressure side. Toro has their own idea. Both are valid. I fertigate everything at the same rate so it doesn't matter to me.

Clear tubing is fine to use. Many water soluable fertilizers don't have a colorant. The stuff I use is just white. I just look in the tank if I need to. When I did use colored fert I could see it in the clear tube.

The settings on the injector control mix ratio. 3000:1, 5000:1, 1000:1. This means 3000 gallons of water to 1 gallon of fertilizer mix, etc. Each fertilizer has a maximum amount that can be dissolved in water at any one point.

Have you ever poured salt into water? It will keep dissolving until eventually no more salt will dissolve. Then the salt just sits on the bottom of the glass until more water is added, then more salt will dissolve. The same is true with fertilizer and this is how the ez-flo works. It keeps adding water to the tank and sucking the concentrate off the bottom of the tank.

For your purpose you just want to get it out there as quickly as possible so you set it on the fast rate. There is a chart for the ez-flo to help you get an idea of the flo rate, etc.

http://www.ezfloinjection.com/3-9.asp

How it works:
http://www.ezfloinjection.com/2-4.asp

Fert only gets hard in the bag when exposed to moisture. I usually dump a half to a whole bag in the tank at once so it is less of an issue for me. Clumping seems to happen more with crystalized vs prilled fertilizer. Prilled looks like little BBs. It dissolves slower, but has less clumping and dust issues. I prefer prilled.