Healthy Soil - You Must First Measure It Before You Can Manage It. (Part Two)
New Year’s Day 2020, our daughter wished me a Happy New Year and then asked me, “Dad, did you know that 2050 is as far away from us, as 1990 is behind us?” She nailed me. It was a solid reality check reminding me how quickly time passes and with it technology too.
Thinking back on the nineties, do you remember the advent of the World Wide Web, DVDs, TiVO, PDAs or PDFs? How about MP3 players, USB flash drives, SMS text messaging, Photoshop and pagers?
All of this technology was introduced into the mainstream during the 1990s. Some are no longer used, while others have become a significant part of our daily lives. How about in your farming operation? What technology have you embraced and abandoned? Why?
Technology advances whether we like it or not, it is here to stay. Keeping the “tried-and-true” is good, but not at the cost of better productivity and profitability. You aren’t still getting paged and returning calls from a land line, are you?
In terms of improving and maintaining soil health and productivity, there are some important tools to employ that can help you better measure and thereby manage your greatest asset; the soil.
Base Saturation Cation Percentage:
Not all Ag labs run a complete Base Saturation Percent Analysis [see Table 1; Green box]. This takes time to complete and some labs, for the sake of time savings, will instead run an estimated Base Saturation Analysis or not run one at all. This speeds lab turnaround time, in order to get the results back to the grower quicker. For the amount of effort and resources expended in collecting soil samples, would you prefer to have estimated or calculated measurements, when it comes to your soil nutrient inventory? After all, if you can’t measure it accurately, how can you manage it effectively?
Table 1
Acidified Paste:
With soil paste analysis, ammonium acetate extraction is considered the "gold standard" for soil measurement. It provides you with a good “estimate” of what nutrients you can expect to release in the next growing season. Typically this is shown in parts per million (ppm) and percentage. While this is good information, it doesn’t tell you when these nutrients will be released nor does it tell you in what amounts they will release. This is critical information for certain stages of development and the nutrients needed for those stages to complete successfully.
Think about early season canopy development and how much magnesium is needed for chlorophyll production? Consider the phosphorus required for cell division, early calcium demand for building pectin for strong cell walls and micronutrients needed like manganese for proper seed development, boron to improve internal fruit quality or copper for efficient nitrogen conversion. In each of these early season instances, nutrients are essential and at adequate levels in a timely manner or the plant and crop goes without. It does not matter if the soil cations are imbalanced, there is inadequate soil microbial activity, or fertilizer applications were late, to the plant it all looks the same; deficient. Regardless of the reason or your noble intent, when there are deficiencies present, quality and production potential are limited.
Water Extraction:
Knowing your soil nutrient inventory is a good start, but as you can see, the acidified paste extraction has some limitations. That doesn’t mean don’t do it. Rather, realize that it is a useful tool for measuring soil nutrient content, but it’s not the only tool. Combining it with a neutralized water extraction takes a little more time for lab processing, but provides nutrient release measurements gathered from Field Saturation Capacity irrigation conditions, based on the soil Cation Exchange Capacity. It tells you quite accurately, what is releasing and available from the soil "right now" for plant uptake and crop benefit. This useful extraction method complements the acidified paste extraction and you should be using it.
One other critical detail needs mentioning with regards to water extraction. The purpose of sampling is to get controlled, accurate soil information. In order to do this effectively, variables must be controlled. That is why laboratories use standardized extraction solvents and methods to get precise results. There are some ag labs that perform soil water extraction with growers’ own irrigation water. On the surface this sounds like a good idea because it is “what the plant roots see,” but in reality this skews the results because it introduces a non-standardized extraction medium with the water. The soil is changing and that means so is the soil sample. It is the one unknown variable to be analyzed. Adding the irrigation water into the extraction process places a second variable into the same sample. When blended together, there is no way to accurately determine whether it was the soil or the water that stimulated nutrient release, in the extraction process. Well water is not standardized for extraction and its contents can vary widely throughout the growing season; i.e. rainy winter, heavy pumping, drought conditions, etc. The water quality will change throughout the season based on aquifer activity. This is why the extraction results are flawed because multiple variables are involved.
I have found sampling soil and water separately are much more dependable and usable information. Amending and fertilizing are expensive. Applying incorrectly or unnecessarily due to inaccurate data is costly. When you have individual results, you can much more precisely determine whether you need to address a soil nutrient imbalance, water quality issue or somewhere in between and without guessing.
When neutralized water is used for extraction, you get a much more accurate measurement of specific cation release, whether it be calcium, potassium, magnesium or sodium. Each of the cations have a different effect on the final pH value. When you know which cations are “releasing,” you know which cations are available and also directly affecting the soil pH.
Table 2
Dirty, greasy bolts example:
On your farm, a tractor breaks down. Getting it disassembled, repaired and back to work is critical. Once you have disassembled the broken parts, the dirty bolts and nuts need to be cleaned for reassembly. These parts are caked with dirt and oily, greasy buildup. All of these dirty pieces go into a parts bath, which is filled with a detergent-like solvent. The solvent cleans the grease, grime and dirt off the bolts and parts to a pretty clean finish.
Water is also a solvent, but it is only a weak solution. If you put the same dirty, greasy parts into a bucket of water for cleaning and left them for a few hours soaking, some of the loose dirt would release, but not much of the sticky, greasy and oily residues would come off the parts.
This represents the difference between an acidified paste extraction versus a neutralized water extraction with the dirty parts representing the soil particles. In both examples, there is a certain amount of “release” from the parts (much like cations) dependent upon the strength of the extraction solution. The tighter or stickier the bond to the parts, the stronger the solvent needs to be, in order for release into solution. In that kind of “sticky” circumstance, water extraction won’t release much off of the parts into the solution. But it accurately represents the differences in soil cation release and what you “want” to happen versus what “is actually” happening in your soil. This distinction is vital.
In growing crops, you need reliable tools to deliver the expected results. This is true of fertility and nutrient options, as well as in your soil analysis results. Here’s the challenge, while you want analysis data gathered accurately from a controlled environment of the soil inventory, it’s often not the reality plant roots experience. Crops are not grown in a controlled setting, far from it. They are grown in “real-world” conditions, which can and do regularly change. The better your ability to adapt, adjust and weave together the lab results, production goals and nutrient management plans during the growing season, the better your likelihood of success. This is the “art” of growing quality crops consistently. You cannot control your growing conditions, but you can control your response to them. The information extracted to measure what you have to work with, needs to be as accurate as possible.
In the next SoilMatters, we will discuss Soil Cation Exchange Capacity and Respiration Rate. These are both important analytical tools to more accurately measure soil health, in order to manage its productivity and improvement.
You may already be working with a lab that performs these types of analyses. If not, they are readily available and affordable. Please allow me to show you how to incorporate this technology into your operation and improve your soil health and productivity.
Visit me at www.soilmatters.net and direct message me with Soil Sampling Help in the subject line. I have some information to share with you that will help you get started.
Here’s to your crops’ success!
