This is Aaron Nygren, your local agronomist with Nebraska Extension in Colfax, Cuming, and Stanton counties. This week, let’s talk about things to focus on as you start getting soil tests back from the labs. With margins tight again this year, most operations likely don’t have a lot of extra cash to invest in fertilizer this winter. However, that doesn’t mean that we still don’t have to try and fix fertility issues that are limiting profitability.
So, once you have your soil test in hand, where do you start? First off, always focus first on soil pH. Low soil pH has widespread effects on the availability of nutrients, so focus on spending available money on bringing up pH values to make as much of the nutrients you already have in your soil available to the crop. So how low of a pH can we tolerate? The answer depends on the most sensitive crop in your rotation. If you are growing corn on corn, lime may not be economical unless pH is below 5.5. However, if you grow soybeans or alfalfa, critical pH values range from 5.8 to 6.2.
Example Soil Test Results
Keep in mind that if your lime requirement comes back greater than 2 or 3 tons per acre, it is recommended to split the application over several years. This is especially true if you no-till and don’t incorporate the lime. In the end, if your pH is very low, spend whatever you can afford on lime, even if that isn’t enough to bring it up to the recommended level of 6.5.
For more information on lime, refer to NebGuide G1504
Many of you may also have high pH levels come back. While, high pH levels also affect nutrient availability, this is a much more challenging and expensive issue to correct, so we probably aren’t going to try in a year with limited funds.
If your pH levels are ok, next look at your major nutrients like phosphorus and potassium. For many soils in Nebraska, phosphorus is going to be the more likely of these two to need attention, as most Nebraska soils have high native amounts of potassium. However, we are starting to see some lower soil test K values, so application may still be needed in some situations. After these two nutrients, focus attention on sulfur, then zinc, followed by other micronutrients.
For UNL’s fertility recommendations for corn, refer to EC117
So in summary, I’d suggest looking at how much you have to spend and then invest those dollars in fertility that has the biggest potential return on investment. Remember, the priority of investment is correcting pH first, followed by other limiting nutrients.
To listen to this radio message again or to get more information, visit our local website at croptechcafe.org or give me a call at 352-3821. This is Aaron Nygren, your local agronomist for Nebraska Extension on KTIC radio.
