Today we live in a post-modern world. Post modernism is a worldview that completely rejects the status quo but offers nothing concrete in place of what it so soundly rejects. If that sounds like a bunch of gibberish consider two of its crowning achievements; political correctness and “globaloney warming.”
When post-modernism looks at today’s agriculture it quickly rejects toxic pesticides, GMO’s, food irradiation, implanted hormones, and other aspects of industrialized agriculture. I also find these toxic practices utterly repulsive to good stewardship. Unfortunately it is easy for zeal to outpace knowledge. When that happens non-toxic fertilizer are lumped in with the toxic practices listed above and compost takes on demigod status as a panacea for all that’s wrong with farming today.
As a point of reference my focus when dealing with backyard market gardens is the production of nutrient-dense foods—foods with the highest level of nutrition and the best taste. In other words my focus is on destination (nutrient-density) and not on the route I travel (organics vs. biological). My philosophy when making fertility recommendations is to create the right environment so plants can achieve their full genetic potential. The sweet spot to do this is to combine the best of both organic and biological products.
With that being said let's zoom in on compost by asking a foundational question. What is compost? Very simply compost is a tool to be used when needed. It is not the only tool but, when well made, it is a good tool. To be affective it must be part of an array of various tools. Let’s move on. What properties does compost have? This is an important question. Besides providing digested organic matter and microbial activity compost is a potent supplier of potassium and a fair source of Phosphorous. Before using compost ask yourself, Does my soil show a need for additional potassium? If not you may be better to avoid it. Why? Because compost has one glaring deficiency—it is chronically short on calcium and will imbalance the calcium to potassium ratio of soils in short order. To illustrate this point I need to tie two stories together.
Now You See it – Now You Don’t
International Ag Labs is a member of the Manure Analysis Proficiency Program (MAP) so naturally we test our fair share of manure. We also have a lot of customers who compost manure and so we also regularly test compost. It is interesting that when manure is tested for NPK the analysis, depending on the type of manure, averages somewhere around a 1-1-1. That is 1% Nitrogen, 1% phosphate, and 1% potash. When we test compost on average, we also find 1-1-1. This naturally leads me to an important question for which I have no answer. If manure starts out as a 1-1-1 analysis and it is composted somewhere between 50-60% of the volume of compost disappears during the composting process. If the resulting compost analyzes at 1-1-1 then where did all the P & K go?
It is easy to understand that a fair amount of the nitrogen can be lost to the atmosphere but what about the P and K? They don’t volatilize into the air and if the compost was not waterlogged and had some clay added at the beginning of the process very little would be lost through leaching. This is a puzzling question without a clear answer. Here is my speculation: The process of composting manure must radically change the intrinsic properties of compost such that an NPK (manure) analysis does not reflect the true P & K value of compost.
At the same time I was pondering this anomaly International Ag Labs had a dealer, Duane Headings, who was questioning the validity of a different lab’s potassium reading on their soil test. Consequently he began splitting soil samples and sending half to us. A lot of the soils he sampled were fields or gardens that had been receiving high levels of compost for several years. The other lab results were consistently coming back showing potassium on the high side of adequate but not excessive. Test results from International Ag Labs couldn’t be more striking: On the Morgan test the potassium levels were through the roof. In fact many samples showed more potassium available than calcium. This obvious discrepancy lead to a phone call from Duane and we began comparing notes.
The Bottom Line Is This
Compost, in spite of it’s seemingly low NPK analysis, is a very powerful supplier of potassium. We also learned that not all soil tests can pick up potassium equally—especially if it is being supplied through compost.
With this information in hand we began looking closely at gardens and market gardens that had high levels of compost applied over several years. We consistently found the same pattern: very high potassium, generally high levels of phosphorous and extremely low levels of available calcium. We then asked these same gardeners how their garden was doing. The answers were telling: A lot of bug pressure – It used to be much better – Really poor tasting food – Very low brix levels.
This research lead International Ag Labs to promulgate two new quality indicators based off our soil tests: the calcium-potassium ratio and the calcium-phosphorous ratio. Both should be around 18:1. I have found that if the calcium to potassium ratio is narrow, say at 3:1 or less it is a sure indicator that the garden will not be producing high brix foods until the ratio is widened. Gardens with narrow ratios can still produce abundantly but the food will not be nutrient-dense and the flavor will leave a lot to be desired. While Dr. Reams did not specifically give this ratio he did teach the principle and it is from his desired levels that these ratios are derived.
Interestingly, Dr. Albrecht was quite familiar with this concept and wrote about it. His insight can be found in volume 3 of the Albrecht Papers on page 20. I quote:
"The significant truth that brings soil fertility into control of the composition of our food, and therefore our health, comes out of the facts that in soils under construction by the limited climatic forces, or those with a wide calcium-potassium ratio, proteinaceous and mineral-rich crops and foods as well as carbonaceous ones are possible, and that in soils under destruction by excessive climate forces, or those with a narrow calcium-potassium ratio, protein production is not so common while production mainly of carbohydrates by crops is almost universal."
In the paragraphs following Dr. Albrecht goes on to show that soils with a richer supply of calcium also produce foods with greater minerals, more proteins, and ultimately much better health to the consumers.
Compost is a big word that covers a lot of ground. It is quite evocative and consequently there are so many voices and “experts” that its use and application can be downright confusing. Misconceptions abound and as a result I feel compelled to put compost in its place. As a prime example I would like to quote from The Rodale Book of Composting – Easy Methods for Every Gardener. Copyright 1992. On page 218 it says:
"Apply at least ½ inch to 3 inches of well-finished compost over your garden each year. There is little danger of burning due to overuse, as is the case with chemical fertilizers."
And on page 219 I quote:
"Your garden will thrive if you give it liberal amounts of compost."
Remember my earlier rant about compost taking on demigod status in the land of post modernism? Well here it is.
In defense of the book I find it to be a great primer on small scale composting and it is filled with valuable information and encouragement to be proactive. It is not my intent to denigrate the—rather, I take issue only with the rates of application and the “more is generally better” philosophy of compost use. With that being said let's look at several misconceptions people have regarding compost and a counterbalancing truth.
Misconceptions and Counterbalancing Truth Regarding Compost
Truth: Compost is a very potent supplier of potassium and can very quickly imbalance a soils’ calcium to potassium ratio resulting in a decline of nutrient density.
Truth: Compost should be applied when the soil needs it.
Truth: Soil needs what it needs—not just what compost supplies.
Truth: Compost is a specific tool for a specific job. Other tools are also required to bring a soil to full remineralization.
Since my focus is on producing foods of the highest nutrient density i.e. destination, and not on the route I take i.e. being organic, I have been accused of being against compost. I am not. I am for the use of compost but only when it is needed. I would like to finish this article with a few applications of compost where its use really excels.
What’s Good About Compost?
- Compost recycles nutrients back into the carbon cycle and food chain.
- Compost is excellent when combined with rock powders because it assists in digesting them.
- Compost can be used as a valuable source of P & K to replace the need to purchase expensive commercial fertilizers. I suggest using 3-4 tons per acre if this is the goal.
- Compost is extremely valuable for jumpstarting a poor soil when combined with other needed minerals.
Too Much Compost in the Garden!
Steven and Julie See live in Beggs Oklahoma. Two years ago they wanted to grow a garden producing nutrient-dense foods for their family of seven so they selected 1,000 square feet for a new garden spot. A local neighbor, Joe Esposito, strongly suggested that before they apply anything they should get their soil tested by International Ag Labs and follow the recommendations, which is what they did.
The results came back pretty dismal; very low Humus, pH, calcium to magnesium ratio, and nitrogen; extremely low calcium, phosphorous and soil conductivity; soil tending toward anaerobic; even the potassium was low. This is typical Oklahoma poverty soil. They were rather discouraged by the lab results until I told them “This is the perfect soil to grow a high brix garden because there are no extremes—all we have to do is put back what is missing and the soil will respond extremely well. You will be amazed.” We had a custom blender put together the exact recipe and ship it to them. For 1,000 square feet they needed 128 lbs. of product to be broadcast over their garden composed of soft rock phosphate, limestone, selective commercial fertilizers, microbial inoculants, and trace minerals. They also used nutrient drenches and foliar sprays during the growing season.
The results were phenomenal yields, better tasting foods, and more tomatoes than they knew what to do with. Julie reported that she canned 150 quarts of tomatoes, had plenty of tomatoes for fresh eating, and even gave away a lot of tomatoes to friends and family all from 12 tomato plants.
The next year when I got their subsequent soil report I was quite pleased to see all the progress the soil made but one element just didn’t seem correct. Potassium had risen from 81 lbs. per acre to 435 per acre. It should have been somewhere under 200 lbs. according to the nutrients I had in the broadcast. I immediately called Julie and asked “How much compost or manure did you add to your garden?” The answer: “Quite a lot. We have horses and a supply of fish waste. We compost the horse manure with sawdust and fish waste and added this to the garden along with the broadcast you sent.” I replied that I could clearly see it in the soil report and ended the conversation with a strong warning: While the addition of the compost was an overall benefit and helped you in a lot of ways it also imbalanced your potassium level and ratios. Do not add any more compost or it will be to the long-term detriment of growing nutrient-dense produce.
Julie assured me that no more compost would be added till it was called for on the soil test which is indicated by a dropping potassium level. Incidentally the garden soil had made such impressive progress on its levels of nutrient availability that it only required 37 lbs. of fertilizers and soil amendments to be applied on the second year. She also reported that previously they could not think of walking anywhere on their farm (garden included) when it was muddy but now they could easily walk in their garden because the mud does not stick to their boots anymore. This is one of the beauties of Oklahoma soils—while they many times start out at the lowest level of fertility they are also about the fastest soils anywhere to respond to a remineralization program.