John Kempf (speaker) discusses regenerative agriculture practices and the challenge of accessing soil nutrient reserves to reduce fertilizer inputs. He explains that total digestion analyses measure soil reserves (P, K, Ca, Mg, etc.) that typical soil tests miss, and that cover crops can mobilize these reserves but may take 3–5 years to rebuild microbiomes and may be suppressed on soils with heavy pesticide/glyphosate history. Kempf recounts that an older product, Rejuvenate, markedly increased nutrient availability (examples given), but rising input costs made it expensive; he introduces a lower-cost successor, Revenant, now registered in multiple states, which aims to deliver similar nutrient-release and soil-aggregation benefits, especially when applied in the fall to maximize winter microbial activity. He recommends side-by-side soil analyses to evaluate effects.
Questions this video answers
As much as 40% (reported).
Reported increases of about 20–30%.
Example reported: from 60–70 ppm up to about 150 ppm.
Reported as "registered in a number of states" (no specific states named).
In the fall (to allow winter microbial activity and post-thaw release); fall application yields a significantly greater response than spring application).
Chapters
One of the ideas that's strongly promoted by many advocates of a regenerative agriculture approach is that of tapping into your soil reserve minerals and reducing your input costs, reducing fertilizer costs. And this is a very important conversation for us to have in the present difficult macroeconomic conditions. We understand that many soils, not all, but very sandy soils, are a particular case in point of being an exception. And there are others as well. You can measure this with, you can measure a soil's total nutrient reserves with what is called a total digestion analysis. It's run by a number of different laboratories. And the total digestion analysis can show you the reserves of phosphorus and potassium and calcium, magnesium and other elements that are held in the soil reserves that typically do not show up on a typical soil analysis and that may be accessible by biology. So the, the historical, the proposal commonly has been that to reduce input costs, to reduce fertilizer applications, we will plant cover crops and have those cover crops, the microbiome of those cover crops, absorb nutrients, solubilize nutrients, and transport, transfer those nutrition, those nutrients into the crop biomass. And then that as that cover crop biomass gets cycled, we now have an increased availability of nutrients, particularly phosphorus and potassium and other elements as well, for the benefit of the following crop. And this is, this is generally accurate, but there are a couple of potential challenges with it. One is that the amount of phosphorus and potassium released may not be adequate for the following crop that you're wanting to produce. And the other possibility is that in many cases, when soils have a history of strong pesticide use, a lot of historical glyphosate use in particular, there is a suppression, even when you grow a cover crop, there isn't the dramatic immediate release of these nutrients that occurs if you grow cover crops over time. And so there is this understanding that there is this, this trajectory, this upward trajectory, that we get better and better nutrient release over a three to a five year period as a result of continued cover crop applications. And that is in large part due to the recovery of the soil microbiome. So, and of course, in today's macroeconomic conditions, putting out a cover crop is, is still a lot less expensive than a fertilizer application in many cases. But putting out cover crops is, also has its own set of challenges from a planting and timing perspective. And I'm a very strong advocate for using cover crops. Just for the record, just to be clear, but the question that we should ask ourselves is what can we do to produce this similar type of response even in very difficult conditions? And when we want to experiment and try this approach on new soils that don't have a history of COVID crop applications, but where we need a strong fertilizer and nutrient response immediately in this coming year, what is it that we can do quickly that has very strong economic benefits. And so to, to replicate what a cover crop can do with root exudates in, in releasing these soil nutrients. Years ago, we developed a product called Rejuvenate that was developed initially the the initial purpose for developing it was as a residue digester to speed up residue decomposition for corn residue in particular. And we discovered to our surprise, that rejuvenate had a marked effect on increasing nutrient availability to such a degree. We have a number of soil analysis of treated and untreated side by side split field applications where available calcium levels would jump by, in extreme cases as much as 40%, available phosphorus and potassium levels would jump by 20 to 30%. You might take a soil from 60 or 70 parts per million, all the way up to 150 parts per million, the potassium. So there's these tremendous increases in nutrient availability that showed up in soil as nutrients were extracted and were released from the soil mineral matrix. But the challenge with rejuvenate, as time has gone by, the materials that go into it have inflated in cost, as has everything else. And rejuvenate, 15 years ago, when we first developed it was a very inexpensive material to apply. And today it's no longer as inexpensive as it was. So Rejuvenate had a lot of horsepower in the context of releasing nutrients. So much so that we had a group of growers in the New England states and in various areas where they had very challenging soils and challenging fall conditions for establishing a cover crop. And their nickname for rejuvenate became a cover crop in a jug because they saw the same types of soil aggregation benefits, the same types of nutrient release benefits, the same types of benefits that they were getting from a cover crop, but just resulting from a single application to the soil. So we've been working for the last couple of years on how do we develop a version of Rejuvenate that has these same types of characteristics from a nutrient release perspective, but without the significant costs. And we've developed a new product that is called Revenant. Revenant has now been registered in a number of states. It's not universally available everywhere yet at this point, but Revenant has similar effects to, from a nutrient release perspective and from a soil aggregation soil quality perspective, as Rejuvenate did, but at a fraction of the price. And so this is something that I'm quite excited to talk about because in this particular context, in this economic environment, this can be a replacement for if, if we don't get cover crops planted in a timely manner, if we want to see significant nutrient release from fall until spring, this can be a significant input reduction force multiplier. All of a sudden you get much greater levels of nutrient release and your nutritional requirements the following spring for next year's crop in terms of potash requirements and phosphorus requirements can be just a fraction of, of what they what might be necessary without a revenant application. So the key what occurred with Rejuvenate is Rejuvenate was so impactful and so successful as a product that it was originally intended and designed for fall applications on crop residue to speed up residue digestion. And then we got all these nutrient absorption or nutrient release benefits. And the, the results were so remarkable that growers started applying Rejuvenate not just in the fall, but also in the spring in furrow as part of a starter solution or as a side dress solution. And it was also very effective there. But the key is that if you really want to use it for input reduction costs, for reducing input costs and reducing the amount of nutrients required, you are going to get the greatest response and the greatest nutrient release when it's applied in the fall, so that you have the entire winter period for microbial activity to increase your nutrient availability. If you wait to put it on the spring, you get only a fraction of the response. And the reality is that microbial activity in soil never stops during the winter. Even if the soil is frozen solid, it slows down, but it doesn't stop entirely. And your greatest periods, the periods of greatest nutrient release are going to be in the fall, before freeze up, and then immediately after freeze up after the soil thaws out. If you do have frozen soil, so the response from a fall application is going to be significantly greater than a spring application. And you should expect to see some very nice responses from a soil aggregation soil quality perspective as well as a nutrient release perspective. And I would strongly suggest actually measuring, measuring, using soil analysis, measuring nutrient release before and after or not before and after, because there's going to be natural seasonal variation before and after. But doing side by side evaluations, I think you'll be very pleasantly surprised and impressed with the results that you get from a revenant application.
