Pass the Humus, Please
I would like to get heavy on you here. Consider the amount of effort you exert maintaining or creating order in your life: your sock drawer, your appointment calendar, your garage. These efforts require energy on your part without which your socks would remain in a pile on the floor, your days would be alternately empty and full of visitors vying for your attention at the same time, and your garage – well, you can always just close the door and park in the driveway. The general tendency toward disorder is called entropy and fighting this entropic tendency requires energy which ultimately we get from the sun. Yes, I know, we don’t photosynthesize, but we eat plants, which are the single most important form of life that reverses the entropic trend. Plants tie up carbon, water, and simple nutrients, and form highly complex cell structures, made mostly of carbon, which are mostly celluloses, hemicelluloses and lignin. Alas, they, too, fall prey to entropy and die and decay. Even the sun, as it blazes away at the center of our galaxy burns its fuel supply, heading in a single entropic direction toward extinguishing itself.
Entropy in the soil is called mineralization. If you have read or heard me say that we have very low organic matter in our soil, you should understand that our soils are pretty far along in the direction of becoming mostly minerals. Not to say that we have dead soil, but the soil degradation due to decades of sheep grazing, huge quantities of winter rain, and acidification from eons of conifer forest before that, have left our highly siliceous (i.e. minerally) soils with very low organic matter. This means that the silica oxides in our soil don’t have many carbon-based compounds mixed in with them. A couple of decades of little to no grazing, which allowed grasses to grow and reverse the mineralization of the soil, definitely increased the organic matter in the soil, but only the top few inches.
Temporary reprieves from entropy in the soil are called immobilization. Immobilization takes place through the presence of microorganisms in the soil. When leaves and plants die and fall to earth, plant litter is broken down by bugs, fungi, and other soil microorganisms. Microorganism bodies composed of cell walls, organelles, etc., grow from a diet of dead plant material. In doing so, they reorganize some of the plant carbon and hold it in an ordered form until they die and decompose. The broken down plant matter, along with the dead bugs and microorganism bodies, become humus, the organic matter that we seek. Humus rests in a middle phase between highly ordered, complex carbon compounds and simple, mineral elements. While some microorganisms are directly beneficial to plants by their symbiotic relationship to the plant’s roots (an article-length side topic), mostly it is in the action of decomposition that we take delight in their presence. The little bugs, the micro- and macro- ones, are immobilized reservoirs of order themselves, their corpses and excrement good humus material, and they break down the highly ordered plants to our desired state of humus. Now, why am I, a grape farmer, interested in humus? Plants prefer it. More organic matter in the soil greatly assists in water and nutrient retention. You want to grow healthy plants? Add more humus, please.
The maintenance of some sort of steady state – of a sustainable, non-consumptive, dare I say, immobilized state – is an obvious goal of farming our land in perpetuity. The water in our wine comes from the sky and, yes, we ultimately send it back to the sky. The carbon that is in our wine comes from the CO2 in the air which we all create through respiration. Returning nutrients taken from our vineyard back to our soil is one leak in our vineyard’s ideal closed system. While the organic waste from grape processing – made up of skins, seeds, stems, dead yeast bodies and other organic material called pomace – can and historically have been directly returned to the vineyard floor, the natural processes that break down pomace spread on a vineyard floor are very slow. A more efficient way to return organic matter to the soil is to compost the pomace so it more readily attains that humus phase, in one or two, instead of many years.
My challenge is to wrest away the composting from a big soil amendments company, and to do it myself. The remoteness of the vineyard led us to build the winery closer to civilization, which complicates returning the pomace back out at the vineyard for composting. With the current arrangement, we give our organic waste to someone near our winery who composts it, and then we turn around and buy compost for the vineyard. I have been composting at home since I was old enough to hold a pitchfork, and have two household piles going right now. I’m ready to take on our organic winery waste and I think now I may be able to achieve this goal: The recent economic downturn has meant that the grassy lot next door remains vacant. I am in discussion with the owner on leasing it for 2 months during harvest so I can compost our daily pomace. After harvest, I can easily transport the compost back out to the vineyard.
It must be noted that we intentionally sought poor, well-drained soil in order to grow high quality winegrapes. Over-achieving when trying to improve the soil health can, paradoxically, result in boring wines. While analysis of compost does not reveal large quantities of nutrients – because the constituents of compost are still breaking down – they still slowly release nutrients, and over-composting for many years can have a delayed effect of over-fertilizing. We have found, by proceeding with caution, that our soil has room for improvement before threatening the quality of our wine. In fact, I can hear our plants crying out for help – poor soil indeed!
As long as the sun is fueling our efforts, we can strive to maintain a steady state, to keep disorder in check. As this applies to our farming vines out on our hillside, I really am trying to minimize external inputs, to reuse and reintegrate what I can, and to maintain a happy, balanced ecosystem. As corrupted as the term may be, this is sustainable agriculture, meaning, this is a biological system that can maintain and stave off entropy indefinitely, or until the sun’s combustion begins to taper. One might call it conservation, and it is inherently organic. Certainly integrated describes what we aim for, which is broader in meaning than the Integrated Pest Management or IPM that we practice. As you can see, all these good terms have been co-opted. What then do we call it? Common sense.