Don't forget about PH this fall!!

October 30, 2013, Submitted by Robert Corzatt of Harvest-Max Partners

As fall harvest winds down, it’s a great time to take care of the most fundamental soil amendment that is critical to next year’s cropping plan success. A lot of growers miss the opportunity to get the most “bang” for their fertilizer, herbicide and seed $$$ next year by letting their soil PH’s slip by under the radar screen. It does little good to spend big $$$$ on nitrogen, phosphorus and potassium, while letting soil PH’s go unadjusted to proper ranges.  If PH’s are low, you could be losing 50% of your fertilizer efficiency on the $$$$ you are spending!! With fertilizer costs being a major part of the cost of producing a crop, that has to be taken seriously to get the highest ROI on the $$ we are spending.

Some of the benefits of adjusting PH to proper levels:

  • Improving the physical, biological properties of the soil.
  • Enhances the effectiveness of some herbicides.
  • Supplies calcium, magnesium and other minerals to the soil.
  • Better nitrogen fixation by legume crops.
  • Increases nutrient availability to plants.

Think about how all of this plays together. If we can’t get all of the good out of the fertilizer (N,P, K and micros) that we are putting out and spending big $$$ on, how do we expect to get full return on our herbicide as well as seed $$$$$ spent??

So how do we go about determining “if” we need to adjust PH? Start with a good soil test that was taken in the last 3 to 4 years. We like grid soil sampling on 2.5 or 4.4 acre grids with several plugs taken to form the sample per grid. If your field hasn’t been sampled in that time frame have someone sample it this fall. Don’t guess. There can be huge variability across a field. You don’t want to add Ag Lime to an area that has a PH level above 7.0 or calcium base saturation level of 75%. There is an area a lot of folks also miss. Make sure that you have included on your tests the base saturation level for calcium, magnesium, potassium and hydrogen and in some area’s - soluble salts. If you don’t have those on your tests today ask for them in the future. Most testing companies don’t run them on their reports but they are available. This is some of the most important information on the soil test.

When looking at liming sources make sure to get a good quality sample of the lime to have it tested. There are a lot of sources of lime from Ag Lime from a quarry to water treatment plants and all things in between. You want to know what you are spreading so have it tested. The last thing you want to do is spread a lime source that is high in magnesium on a soil that is already high in magnesium. If you are using water treatment lime, for example, have it tested by a quality lab to determine if there are any other things in it that are harmful to the soil. The other need for testing is to make sure you know what the ECCE or CCE values are to make a proper recommendation of how much lime to spread on the low testing area’s in your fields.

Once you have your soil test and a good lime source test then you can make a proper recommendation on “if” you need to adjust PH and how much lime you might need to spread. Again, most crops like corn, soybeans, wheat and alfalfa like to be in a general PH range of 6.4 to 6.8.  Anything below that range needs to be adjusted. If you are unsure with what you are dealing with, seek help! There are a lot of folks with good software programs that write variable rate prescriptions to take care of low testing spots within a field.  For years, some growers took the approach of spreading 2 tons of Ag Lime every so many years whether they needed it or not, while others didn’t worry about spreading anything. We have seen all kinds of scenarios over the years, from fields that are really low from no PH adjustments to high from just spreading because it was the way dad or grandpa did it.

In closing, PH is the most important soil amendment. It is basic and fundamental to row crop production in so many ways but probably the most ignored by a lot of producers. It needs to be monitored and watched with care because if it’s too high it is a problem but left too low it’s a huge problem and you are leaving money on the table! If resources are limited, I would rather see a grower spend money to adjust PH than spend it on P and K for a year. I see growers spend $20 to $30/ac all the time on “snake” oil or “spoof” juice that promises a 10 or 15 bushel gain in corn or 5 bushel gain in soybeans. More often than not, they don’t work. Those same growers that spend money on the “quickfix”, won’t spend those same dollars on adjusting PH when it’s proven that it does work in so many ways!  Think about it and give it some thought. Have a safe and great fall harvest season.

If you need more information or have questions, please let us know!