Instead of putting more on, balance your ratios
Addition through subtraction sounds like something the baseball player Yogi Berra would say — this year’s new pitch clock, which has shortened games by 30 minutes and thus made games more exciting, is surely an example of that!
In agriculture, though, we fall in love with the same applications year after year, not knowing what we might be creating. When we continue to do this, we create excesses, thus creating antagonisms. To add another analogy, we enjoy and stay longer at parties if we can eliminate any antagonistic people — so let’s create some good diversity without a domineering environment so we can all have fun!
Our propensity to add more than what we need (more-on theory) creates self-inflicted antagonistic excesses. That is why I am so adamant about getting good, accurate, soil reports so we can accurately assess how to properly amend our soils.
Thinking in Terms of Ratios
As I have emphasized before, ratios are extremely important, and we must try to maintain them as best we can. Sometimes we can’t get the perfect ratios, but we can create an atmosphere that can buffer these interactions to improve nutrient uptake.
The best buffer in our soils is going to be carbon, and we should try to get our organic matter in the 3 to 6 percent range. In poor soils, I like to incorporate biology primarily for that reason alone. It’s going to take time to properly amend a poor soil, but in the meantime you can create productivity by adding biology and other carbon inputs.
Another problem I see in general in agronomy is an obsession with wanting to correct pH first. Yes, pH is important, but by buffering the soil with carbon we can give ourselves some more leeway. I have found that as you balance your soils, the pH finds a way to correct itself. I have yet to find a balanced soil that has a pH that is out of line. In Northern California, we have mostly high-magnesium soils, but we also see calcareous soils. They both create their challenges. High magnesium creates antagonism with potassium and nitrogen, so if we can shift that to a more desirable ratio, we will start lowering N and K inputs. A calcareous soil will antagonize trace elements, with iron and manganese being the most severe. Both soils can have a high pH.
So, what do we do if we have a high-magnesium soil with a high pH? The typical answer is an application of gypsum, which in most cases can suffice, but we must investigate the percentages a bit closer before we make an informed decision.
Let’s say we have a calcium percentage of only 55 percent and magnesium at 35 percent, with a pH of 8 and a CEC of 24. In this case, gypsum would be a poor choice. Why? Well, to correct this would take multiple tons to get our Ca:Mg even close to the desired 7:1 ratio. One ton of gypsum will add 360 pounds of sulfur — 180 ppm of S (one acre equals two million pounds of soil). Overapplication of gypsum can easily skew your desired S:P ratio of 1:1, thus creating a phosphorus antagonism.
Another ratio to consider regarding sulfur is the carbon-to-sulfur ratio, which should fall between 200:1 and 400:1. When the percentage of Ca is below 60 percent, limestone is the best choice to get levels up.
I feel that adding limestone with elemental S, or a blend of limestone with gypsum, is a better route for a couple of reasons. First, limestone has a higher Ca percentage. Second, you can customize your blend to make sure you do not create any excess sulfur that could impact your phosphorus availability. As we replace Mg with Ca, we will see the pH self-correct. According to Graeme Sait, magnesium has a higher influence on high pH than calcium by a factor of 1.4:1. As Carey Reams has stated, “pH is an effect, not a cause.”
To finish fixing this soil I would add amendments of soft rock phosphate mixed with humic and a small amount of sulfur, which is useful to break the bond between calcium and phosphorus ions. Once Ca and P are separated, the humic will help chelate them to maintain their availability. Finally, a two-ton application of compost will help build soil carbon by enhancing biology.
Addresses other Excesses
Let’s talk more about some other excesses. Sodium is one bad dude! First, it has a strong affinity for water, and the negative pressure generated from evapotranspiration is not enough for roots to pull the water from the sodium. The plant has no choice but to absorb the sodium to draw in the water, which then leads to toxic levels of sodium in the tissue. Another problem we have with sodium is direct competition for the uptake of potassium. If levels of sodium are higher than potassium, then you are sure to have potassium uptake problems.
So, what can we do to remediate sodium? We can amend our soils with other cations, depending on what our ratios are telling us. Though most sodic soils are also high-pH soils, I often see the application of sulfur to try to fix pH — instead of addressing the real problem of displacing the sodium. Yes, sulfate can help remove sodium by forming Na2SO4 so it can leach out, but is it really helping with the physical nature of our soil? We can do better by displacing the excess sodium like we do in a high-magnesium soil: with additional calcium, provided the soil reports calcium as low. Two birds with one stone.
Carbon is another great tool to alleviate sodium. Carbon in the humus form is best since it will have the best cation exchange capacity. This is where the application of humic, biochar or leonardite can help.
Another consideration would be implementing a source of plant-available silica. Silica implementation has been shown to boost plant growth and nutrient uptake and to provide improved tolerance to abiotic stresses, such as drought, salinity and heavy-metal toxicity. I have used dry magnesium silica or dry calcium silica to help in my battle with sodium. Silica is associated with plant cell structure, and when used in conjunction with calcium and boron you have the perfect trifecta to create a strong cellular structure that resists disease and insect pressure. Silica has other superpowers besides helping with cell wall strength. I have noticed that when I combine it with a humate, my sodium levels lower, giving rise to increased potassium numbers in my plant tissues. I will discuss silica in more detail in a later article when I talk about my big five nutrients.
Another excess that is quite common in our area is chloride. This excess has become increasingly prevalent, especially after our three-year drought and the subsequent reliance on groundwater. Chloride will compete with phosphorus, sulphur, and nitrate nitrogen. It is essential at low levels but is toxic at high concentrations. I have seen excessive chloride choke off phosphorus in the tissues. Another observation is that web-spinning spider mites love high chloride levels. I have used injectable and foliar carbon to neutralize chloride, lowering levels in my tissues while also allowing my phosphorus numbers to rise and controlling web-spinning mites without a spray.
Aluminum is another element that can be very detrimental to plant growth and its ability to fight disease (even in soil pH of 6.5 I have had unacceptable levels). There are documented ties to aluminum and human health concerning dementia diseases, such as Alzheimer’s. I feel aluminum is doing the same in our crops by not allowing the plant to communicate with our soil biome, thus giving it a weak immune response. Aluminum has been correlated with decreased chlorophyll content and inhibited photosynthesis. It also interferes with enzyme activities, cell division in root apices and DNA replication. The main physical symptoms of aluminum toxicity are inhibited taproot extension and lateral root development. This poor root structure makes the plant susceptible to drought stress and reduced nutrient uptake, especially calcium, magnesium, and phosphorus.
The addition of calcium, magnesium, phosphorus, and silica will alleviate aluminum’s inhibition of root elongation. I have seen good results using aragonite, calcium silica and soft rock to minimize aluminum toxicity. Tissues on treated vs. untreated have shown half the aluminum. Organic acids such as citric, oxalic, malic, succinic and fulvic ameliorate Al phytotoxicity. Even some mycorrhizae help protect the plant from the phytotoxic effects of aluminum.
Other excesses we must watch for are self-inflicted sulfur and potassium over-applications. Reductionists are attempting to hammer down soil pH with substantial amounts of gypsum and sulfuric acid, which will lead to additional salt problems. Over-application of manure has created high potassium and sodic conditions.
Over-application of copper (especially in organic systems) is a frequent problem I find. The zinc-to-copper ratio needs to be 2:1, and it’s often backward where the over-application of copper has occurred. Another problem with high copper is the antagonism of bacterial endophytes. James White talks about this in his rhizophagy cycle research.
So, when we see a crop respond to an application, let’s proceed with caution and not fall into the more-on approach. Make sure you know the analysis of the product you are applying and pay attention to ratios to prevent subtraction through addition. When proper ratios occur, we will find it’s so much easier for the crop to get the nutrition it needs. It is surprising to see that you can increase the levels of phosphorus when you lower chloride or sulfur excess — potassium when you lower sodium — calcium when you lower magnesium, potassium, or sodium — nitrogen when you lower magnesium — and so on.
Dr. William Albrecht and Dr. Carey Reams created guidelines for proper ratios; though they may differ slightly, they are surprisingly similar. Again, I will refer to the Ideal Soil v2.0 handbook as a good place to start.
So, as Yogi Bera might say … when you come to a fork in your agronomic road and have to decide between balancing soil ratios or putting more on — take it.
Jim Pingrey is an agronomic consultant in northern California’s Sacramento Valley.
