By Darren Hefty
Some areas of the country like Nebraska, southern South Dakota, Kansas, etc. are pretty dry going into this spring. Other areas are blessed with good soil moisture levels. No matter which of these situations you find your farm in, that situation can change in a hurry this time of year. Either way, you still need to be careful when you’re applying fertilizer in the furrow this spring. Here are some ideas you may consider.
We classify fertilizer put in the furrow as “pop-up” fertilizer. When you hear the term “starter fertilizer,” that could be an in-furrow treatment; but it more likely refers to a placement outside the furrow, such as a 2 X 2 (2 inches below and 2 inches to the side of the seed). A 2 X 2 placement offers a degree of safety by keeping a barrier of soil between the seed and the fertilizer. This is important because while fertilizer contains the plant food that your crop is looking for, it also contains a level of salt that could potentially be dangerous or even deadly for your young plants. Here’s how that works.
Salt attracts water. When there is plentiful moisture in the soil, having a little salt in the furrow, especially in corn, is not a big deal. There’s enough water present that the salt can pull some away from the seed while still leaving enough to get the seed to germinate and begin growing. When soil conditions are dry and/or when your soil has a light texture (sandy) and a low CEC (not much organic matter or clay content), you are at a much greater risk of having issues with salt causing injury or even death to your seed or young seedlings.
Our general rule of thumb for corn in 30-inch rows is to use no more than five pounds of salt in the furrow. This translates to roughly three gallons of 10-34-0. Soybean plants can’t stand nearly as much salt; one gallon of 10-34-0 would be about it. Even then, we would really like to see that fertilizer NOT directly on the seed. A better alternative, especially if you need to apply more fertility than this, is to use Pro-Germinator for phosphorus and Sure-K for potassium. Both of these products have exceptionally low salt index ratings (i.e., low salt content) and have performed very well on our farm. While I wouldn’t recommend using rates this high, I have personally used up to 20 gallons total between these fertilizers in-furrow on my corn without noticing injury to the plants. Another farmer in the area accidently applied about 40 gallons per acre thanks to an equipment malfunction and did not hurt his stand. Again, these are not rates I’d recommend; and I wouldn’t expect an economic return applying such heavy doses of fertilizer. I’m simply saying that Pro-Germinator and Sure-K are very safe products.
In summary, pop-up fertilizer can be a great thing; but be careful how much fertilizer you apply in the furrow each year. If your soils are light and/or dry, be especially conscious of the amount of salt your fertilizer contains. Salt can pull water away from your seed and potentially cause injury or death.