End of Year Irrigation


It’s here: the last month. 2020 is winding down; pray for rain. In my humble opinion, it couldn’t end quickly enough. I’m ready to forget 2020 faster than I forgot where I put my keys. For nut farmers, we hope the worst is behind us with low prices and stalled markets; yet, we trudge on. We catch our breath, fix any equipment we wore out this year, service our systems, clean our irrigation lines, apply our soil amendments and fill our soil profile with water. “Wait, what?”, you ask. “I’m tired, I’m done, and I don’t have any water left to be delivered!” I hate to be the bearer of bad news, but I’m about to be. It was dry through October. “Thanks Nostradamus, tell me something I didn’t just live through.” Turn your wells on; the soil needs it. This tale has a happy ending if we do things right.


Flush Those Soils

Nothing draws water down better than water. It’s not light, and gravity helps it do its thing. Many of my clients get worried that putting bad water on now will be detrimental to the roots. With root flushes winding down, we don’t run the risk of affecting that significant occurrence as much in December. The heavier salts and higher EC’s are never a good thing if you can avoid them unless we have a dry fall. Solubilizing the beneficial cations — Ca, Mg and K — will help unlock the sodium attached to the soil colloids. With cleaner water coming thanks to Mother Nature, we want to make the most of it to clean up our ground. If cleaner, more acidic rain water hits very dry soil, it goes more lateral than vertical unless you are growing trees on sand. Any salts we have pushed to the edge of our wetting patterns get pushed back in with lateral movement once the rain comes and saturates our orchard rows’ centers. We don’t want that. The farther away and down we can get the salinity ball, the better chance we have to clean it up. With an already-saturated soil, rain water will push the bad water down and dilute it further.

To exacerbate that, it has become a good practice for many of my clients to acidify the water being applied now as we fill that profile. Decreasing your pH with your injection system can go a long way to breaking up carbonates and bicarbonates. You’ll be able to clean up your irrigation lines, breaking up the accumulated lime scale. Solubilizing Ca and K should also increase the amount of sodium pushed below the root zone. Bulk applications of sulfur, Tiger 90, banded sulfuric acid, Acidifier and hydronium acid have played major roles in freeing up a lot of earth metals and micronutrients on progressive soil tests the last few years. Prove it to yourself; take a before and after soil test to make sure you are applying ample amounts of the chosen product to achieve the desired results. We need to stop guessing as farmers and have our consultants show us the actual results. Know you are applying the products correctly.

There is a good way to get a feel for the ratio of what should be in the soil solution to what is actually in the soil solution. Look at the meq/l in the saturation paste extract section of your soil test. Multiply the cation times its atomic weight/charge. Ca weighs 40 atomic units, but has a charge of 2. So, multiply it by 20. If you divide that number by the parts per million shown in the soil test, you’ll have a better idea of what is actually soluble in your soil water compared to what should be based off the parts per million in the acetate extraction. That ratio will put things into perspective. Sodium is 23 atomic units, but only has a single charge. Multiply the meq/l times 23. Then divide by its ppm in the soil. You’ll find the ratio is significantly higher with sodium than the other cations. It’s very soluble and occupies a large percentage of your soil solution. That’s what the trees are drinking every day. Here’s more bad news. Those tests are run in the lab with distilled water; thus, those numbers are worse in actuality when the water we are applying is of the low quality we are often applying. Yep, I said it, it’s worse in reality. So, be proactive. This is not the time to “hope for change”.


Proactiveness is Key

Turn the pumps on a few days before the rain is coming. More if you need to run a few short sets to get the water into sealed and tight soil. Get the ground wet. Acidify your water. Add some soluble Ca or K if those nutrients are low and/or sodium is very high. Check the water at the end of your system. Open the farthest line from the system and make sure the pH is adjusted properly. Don’t guess. It’s very hard to get your pH too low for these winter wetting applications. I have clients who have been worried they would drop the pH too low. Remember, you’re not doing this all season, and even vinegar is 3 pH. You can drink vinegar, and the soil is a much better buffer than your gut. We have slugged in our Acidifier, taking the water to a pH of 1 at the end of our lines and turned the water off. After sitting in the lines for a day, turn the system on and open up the ends of your lines. You’ll clear all kinds of sludge and scale. The secondary rinse of any unreacted acid in the lines will help bust those salts apart. Be proactive. Clean your soil. Break up the salts, free up the sodium, and let Mother Nature do the heavy lifting. Here’s the happy ending. Next spring, bloom, new growth, leaf expansion and crop yield should be better for you. Good management now trumps hoping Mother Nature will do it all for you. Then, pray for rain.