By Brian Hefty
If you want to learn more about this topic, please join us at the free Ag PhD Field Day, July 25th. We hope to have several farmers and researchers speaking who have been using tile lines to both remove excess water AND irrigate
Having good drainage is an absolute must if you want top yields. Even in traditionally “dry” areas like the Dakotas, almost every year there are periods of excess moisture and high water tables. By simply having a water table too high for a week or two, it is quite common to see yield losses of 25% or more. Putting that in dollars and cents, if you have $5 corn times a 160 bushel yield, that’s $800 per acre. Multiplying that by 25% is a loss of $200 per acre. Since you can often “spot tile” for $200 per acre or pattern tile for $500 to $1000 per acre, tiling is usually a great investment.
Of course in “dry country”, we are also concerned about the opposite end of the spectrum. If the weather remains dry and hot for an extended period, many farmers have asked if they could use those same tile lines to pump water back into a field. Yes, this can be done.
The only first-hand experience we have with this so far is where we have tile lines running from a heavy area of a field of ours into a sandy area. We have successfully pulled excess moisture from the previously poorly drained acres and moved that water into the sandy areas, increasing yield in both. In order to make this even better, I could certainly add some more lines in the sandy areas or install some sub-surface drip tape there; but for now, we’re happy with the results.
If you want to irrigate through your tile lines, you will likely need 3 things:
- Tile lines closer together than normal. Instead of 40 or 50 foot spacings, you may want 10 to 20 foot spacings
- Control structures to shut off the flow of water out of your lines. These work better in flatter fields, unless you want to put a lot of control structures in.
- A well or some other source of water to pump back into your lines.
The good news with pumping water in below ground is that efficiency is very high compared to pivot irrigation. I have been told that it usually takes half the amount of water to do the same job, but that obviously varies a lot depending on environmental conditions.
The bad news with this is it will cost additional dollars compared to just tiling to improve drainage. However, adding an irrigation system always costs money – you just have to pencil it out. Will it always be worth it? I doubt it. But could it pay in a lot of situations? Probably. We will likely be putting something in to start testing this on our farm; but in the meantime, we plan to be talking more to farmers who have done this in the past. As I said at the beginning of this article, we should have some of those farmers at our Field Day July 25th on our farm near Baltic, SD, so please join us!