Smartcherry spoke with Andrés Arias and Diego Kirberg, partners at the consulting firm Regenerative Soil Management, who delved into the relationship between nutritional levels and cherry size, firmness, and post-harvest condition, adjustments to nutritional programs in new orchards, and the impact of new technologies on improving nutritional diagnosis in this tree, among other interesting topics.
What are the most common nutritional excesses and what problems do they cause?
– Andrés Arias: First, we need to differentiate between toxicity and excess. One of the most common toxicities we see is when too much potassium chloride or muriate is used, and you can see some leaf toxicity. That’s more than just a nutritional excess. It’s the over-toxification or excessive use of an element that isn’t intrinsically essential for the plant’s nutrition. But then there are other nutrients, like nitrogen, and we often see nutritional excesses with nitrogen, especially regarding ammonium compounds, which can affect fruit quality.
There’s a relationship after harvesting the fruit: how much nitrogen versus how much potassium or calcium was present. And obviously, the higher the nitrogen content in the fruit and the lower the cation content, the worse the fruit’s condition. So it’s important to emphasize that while nitrogen is an essential element, an excess can lead to fruit quality problems that are obviously very serious in commercial terms. Another excess we tend to see, rather than an excess per se, is applying several cations together at phenologically incorrect times. For example, magnesium and potassium are antagonistic. If I apply both in high quantities, I’m not actually benefiting the system as a whole, but rather creating competition for absorption at the soil level. Therefore, there are specific phenological stages for each nutrient. This can obviously affect the firmness, size, and color of the fruit. These are the kinds of excesses we see, in short. We usually see excesses associated with nitrogen or with the misuse of cations, which are applied indiscriminately in combinations.
Analyzing this aspect, which is a key factor when exporting cherries, how are nutritional levels related to size, firmness, and overall condition of the cherry tree? Thinking specifically about post-harvest.
– Diego Kirberg: As Andrés mentioned, the fundamental nutrients for fruit quality are, most importantly, calcium, and we must always consider the optimal times for calcium application. In other words, this is generally applied quite early because it’s necessary to target cell division, that is, from the beginning of flowering until the fruit has just set at 3.5 mm. Often, there’s a problem in some areas with the timing of application because they haven’t started irrigating yet. So, it will also depend on whether those timings need to be addressed, choosing the most appropriate times depending on the production areas. And then, clearly, potassium is fundamental for fruit size and condition, and that’s during the second stage of fruit growth. If you have good levels of potassium in the soil, it’s a nutrient that can’t be missing from fertilization to achieve good production and yield.
How does nutrition impact floral induction and also production, thinking ahead to the next season?
– Andrés Arias: In general, nutrition is obviously going to be fundamental because, in the long run, this is still somewhat guided by the law of the minimum. If we have any nutritional limitations at the time of floral induction, or when we’re building up reserves, it can create a problem in the future. It’s very important not only from a nutritional standpoint, but also to identify the limiting factor that might be affecting future results. In this respect, regarding floral induction, reserves, and so on, it’s crucial for us to emphasize that the soil must contain nutrients, not only in terms of quantity, but also in terms of availability and timeframe. For example, when we talk about calcium and say, “Well, I need more available calcium,” the amount of calcium in the soil is one thing; the ability to solubilize it is another, and then there’s the question of how long it remains soluble in the soil for the plant to absorb. Regarding the question of ‘how does nutrition impact floral induction and the production of the following season’, it has a total impact, since it will be one of the limiting factors in the formation of assimilates from the reserves, which will generate all the budding in the following season.
Currently, analyses of reserves are being conducted, for example, at the root level, such as those related to starch or amino acids, particularly arginine. It’s important to emphasize that it’s not a matter of one or the other, but rather being prepared for both. Starch, in a way, will be the plant’s energy reserve, which can later lead to flowering, or rather, new growth in the following season. But if the corresponding amino acid content is insufficient, if arginine levels are inadequate, one might see good bud break, but then a high rate of fruit drop, because ultimately, while the plant had the energy, it lacked the structural components, the building blocks to construct new proteins and cells. Therefore, it’s crucial that nutrition guides the storage of reserves, obviously ensuring that the plant performs photosynthesis and that we have favorable weather conditions.
How can nutritional programs be adjusted for young orchards versus those that are not so young?
– Andrés Arias: One of the common mistakes we tend to see is that when the orchard is new, not much is applied. People say, “Well, I’ll just apply a little nitrogen for growth, but I’ll leave out potassium because I don’t have any fruit yet.” Young orchards are crucial for us, as this is the time when we have the opportunity to improve the soil without later, when we already have production, paying the price for not having fertilized earlier, which can affect yield or fruit quality.
The first few years, when we don’t have productive results, are a very good time to address certain soil problems. For example, if liming was needed, the lime has to be applied physically because the amount is very high; it can’t be applied through irrigation. But in the case of potassium, we have three or four seasons to reach our target or desired potassium level in the soil. We often see the mistake farmers make of not fertilizing in the early seasons, even when potassium levels are low. Then, when the harvest arrives, they have to apply very high amounts or simply don’t fertilize at all.
Our recommendation is always to start preparing the soil early on so that when the orchards become productive, the soil, or “the bank account,” as we say, is already full and ready for the plants to thrive and produce good results. We urge you not to think that just because the orchard isn’t producing, you don’t have to do anything, that you only need to apply Buria or Nitrogen and nothing more. Quite the opposite. Soil preparation in the early stages is extremely important. Another example of this is when we have very vigorous growth; insufficient calcium can impact cell formation, leading to problems such as wood rot and sun damage, which obviously allows diseases and other issues to take hold.
It’s not just about adding nitrogen and saying, “Well, I won’t do anything for the first three or four seasons.” No, quite the opposite, you have to build a good structure for when the tree is already producing. And regarding mature, older orchards, I would say that in general, once you have the soil in good condition, the plan afterward is simply to replenish what you remove. But what is very important, and what we always emphasize in mature orchards, is that having a full bank account is not the same as having access to it. In that respect, we are much more concerned later on, rather than applying fertilizer—which we believe is necessary in the first few seasons when you should bring the soil to a chemical equilibrium—we are much more concerned later on with what Diego mentioned: maintaining the physical and biological condition of the soil. Why? To have access to the nutrient source, to water, and to keep the soil in good condition. In general, one tends to see that one of the most common problems in older orchards is not so much related to nutrition, because we have applied fertilizer, but rather to soil compaction. For us, it is much more important to maintain it through other means than just focusing on fertilizers in mature orchards.
Looking at the technologies available in this field, what new technologies or methodologies are improving nutritional diagnosis in cherry orchards?
– Andrés Arias: First, we always encourage farmers who aren’t taking action to start doing something. It’s never too late; the sooner we start, the better. But I can tell you that we, as a company, currently have new technologies. One of them is soil mapping using infrared spectroscopy, which allows us to perform monitoring that is faster, less expensive, and more precise, providing a higher level of detail in the map so we can make more timely decisions. These new technologies are precisely what they aim for today. It’s not that laboratories are currently insufficient in their results, but we know that we often miss the deadline for getting results, and when we finally get them, the lab is overwhelmed or experiencing high demand, and by the time we receive the results, it’s too late to take appropriate action. So, in that respect, we want to convey that today there are new technologies that allow us to create maps faster than those produced by laboratories, ultimately enabling us to have a much more rapid response. In that sense, we also have measurements that are not only chemical, but also physical and biological, which can now be monitored and are important to track. These technologies, which were once exclusive, are now more common.
– Diego Kirberg: Right. We always focus on and consider the various chemical, physical, and biological limitations, and we believe it’s fundamental because, as Andrés mentioned, it’s not enough to simply have soil nutrition or achieve that nutrition through management practices. It’s also key to enhance the soil microbiology through products that make that nutrition available and usable. That’s why it’s also essential to evaluate the impacts of the management practices we’re implementing.
We also take measurements, for example, of soil microbial mass, soil respiration, and the fungal-bacteria ratio, which will give us parameters and indicators of the soil’s biological activity. On the chemical side, as Andrés mentioned, we’re working on the spectrometry of these maps, and on the physical side, we’re measuring penetration resistance. These days, we’re not just checking compaction in test pits, but we’re also creating maps across large areas by measuring vertical penetration resistance. So, we’re gathering information, and we also regularly measure soil characteristic curves to understand the pore distribution in the soil. This helps address what Andrés pointed out at the beginning about the differences between soil textures and how we can modify storage capacity through management practices, perhaps in a sandier soil or in a more clayey soil. Therefore, I think farmers are much more open to taking more measurements these days because it ultimately allows them to make data-driven decisions, which is what we always try to offer in our consulting services, and to quantify the management practices implemented over time.
– Andrés Arias: What Diego says is very true regarding aggregate stability and all of this. Ultimately, what does this mean for the farmer? The logical question is always, “Okay, I implement a management practice, but how will that practice translate into economic results?” Tracking and quantifying results allows us to quantify them, because these days, the big issue is not identifying your soil limitations. So, for example, someone might say, “Hey, what should I spend my money on today? A rooting hormone, umic acid, more fertilizer?”—a list of things. If I know I have compacted soil, great, maybe I can skip the rooting hormone today and apply a dose of umic acid, a soil decompactor, that helps more with the physical aspect. Once I’ve resolved that, perfect, we can move on to something else, or the complete opposite. Perhaps I’m working with sandy soil, there’s no compaction at all, it’s very poor soil, and I need to add more fertilizer. But if I don’t have a comprehensive measurement, if I don’t understand that soil isn’t just about nutrition, but about life, biology, physics, chemistry, oxygen, and temperature, then understanding where that limiting factor lies is what allows us to make good use of resources, and that good use of resources is ultimately what leads to results. Today’s technologies are largely focused on that: finding the limiting factor, resolving it, but always by quantifying and assigning numbers to it.
