How do we increase yield potential in 2016? Part 2: pH and Nutrient Imbalances

With the downward trend in commodity prices, our on-farm yield levels must be raised in order to be profitable. The best way to do this is by eliminating yield limiting factors, because once we start letting our yield slip backwards there is no method to recover what has been lost.

The best way to think about yield is in terms of “subtraction” and not “addition”. Every seed, in every crop, in today’s marketplace has the genetic potential to produce well above our common established on-farm averages. So why are we not producing 100+ bushel soybeans and 300+ bushel corn? The answer is simple: yield limiting factors.

They exist in every facet of production, from: weed control, nutrient imbalances or deficiencies, disease problems, insect damage, environmental stress, pH imbalances, and even the use of chemicals that plants can not properly synthesize.

Over the coming weeks, I will touch on each of these issues in a hopes of arming you with some knowledge of how to take your on-farm yields to higher levels.

Last week, we discussed weed control strategies. In today’s blog entry, I am going to discuss pH and nutrient imbalances and how they affect yield.

soil_ph_nutrient_availabilityThe chart above demonstrates how pH range affects nutrient availability. I am sure all of us have heard or been told that the proper pH range for row crop production is 6.5 to 7.5, but I am willing to bet that none of us truly understand why.

As you can see in the above chart, that range allows the most nutrient availability to occur. However, even that range is generally too broad if we want to raise our on-farm yield levels. If we can maintain a pH level between 6.5 to 7.0, then we are going to have an even better chance of making nutrients available to the crop. The only problem with that is, it takes very intense management to keep soil levels within that pH range. This can be very costly. That is why the standard recommendation has always been 6.5 to 7.5 pH.

So, if maintaining a smaller pH window is too costly, then how do we get higher yields without as much expense? Easy, we manage the plant. Once we have a an established pH base line within the recommended parameters, we put together a system of tissue sampling our crops to maintain proper nutrient balances.

Every high yielding, record setting producer out there (i.e. Randy Dowdy, David Hula, Kip Cullers, etc) are already tissue sampling their crops and have been for a while now.

By tissue sampling a crop, at the correct growth stages, we can figure out any imbalances that we may have within the plant before critical yield stages are reached and correct them. Tissue sampling also allows us to be able to apply the specific nutrients needed at the specific rates required. We no longer are relegated to buying a “silver bullet” micro-nutrient solution from the local retailer. While those products have their uses, they do not help us solve nutrient deficiencies, as many times we are looking for just one nutrient and need it to be applied in greater amounts than that compound is offering. Also, each crop is different and requires different nutrients for it’s production needs.

Below, you will find a link to a publication that Mississippi State Extension puts out that details how and when to take tissue samples of your crops. This is a good general reference to use but needs to be fine tuned for yield purposes.

Plant Analysis Sampling Instructions

While the above publication does list when to sample, it does not necessarily specify the best time frame in terms of yield management. For example, on corn it says to sample the plant when it is less than 12 inches tall OR before tasseling. That is a pretty broad range. In actuality, if we are tissue testing for yield, we should be testing corn from V2-V4 time frame, then again just as the tassels are starting to emerge. A V6-V7 sample can be pulled, but it is more often reserved for emergency applications in the event the plant is showing signs of a deficiency and we want to keep yield from slipping further backwards.

Mississippi State also runs a lab for tissue sample analysis, among other things, and I would be happy to send off any samples you need analyzed. There are also other labs nearby capable of running your samples. (A&L Analytical Laboratory in Memphis and Southern Soils Laboratory in Yazoo City)

All samples will come with a general recommendation in the event there are nutrient deficiencies. These recommendations are made based on each labs base line of what each crop needs to produce a certain yield level. Many times we will receive a sample back with more than one nutrient showing that it is limiting. We can usually identify that one nutrient is way more limiting than the others though and by correcting it, we can raise the levels of the other nutrients as well. For example, a sample shows that Nitrogen and Zinc are both limiting on a corn sample sent in, when really it could just be that the Zinc level is deficient to the point that the plant can not adequately use the Nitrogen that is already present in the soil profile.

I know a lot of this information can be a bit confusing, since many of you are new to this approach of production agriculture. If anyone is unsure about timing or would like me to help them put together a strategy for pulling samples, or would even like for me to pull these samples for you, I will be more than happy too. That’s part of my job as a Mississippi State Extension Agent.

As always, if anyone has any questions or would like to sit down and talk further about ways to mitigate risk and raise on-farm production levels, give me a call at the office (662) 326-8939, email me at, or just pop your head in anytime your near.






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