Soil building plays such an integral role in organic agriculture, I have decided to divide this particular principle into three parts. This first part will be an introduction to the topic and an explanation of the importance of it in organic agriculture. The second part will be a discussion of how soil building affects our system in regards to a lack of rain, snow and soil moisture. And the final part will include examples and tips for developing a complete rotation scheme.
Part 1: An Introduction
The second great principle of successful regenerative organic systems is a good soil building program. If diversity is the engine of a regenerative organic system, then soil building is the fuel. You could have lots of diversity—the best engine in the world—but if you do not have soil building crops in your rotation, your system will stall out—you will run out of fuel. This topic brings into focus one of the main differences between organic and chemical agriculture. In chemical agricultural systems we feed the plants and ignore, for the most part, the role of the soil. In organic agricultural systems we feed and nourish the soil so that the soil can feed and nourish the plants we are trying to produce.
When I refer to soil building, I am not only speaking of adding nitrogen to the soil, or other elements such as potassium, phosphorous or sulfur. I also want to consider the levels of life and vitality in the soil. It is not as simple as just adding a straight dose of nitrogen and other elements. That is what our chemical farming friends are doing when they fertilize their fields with nitrate salts, urea or ammonia for nitrogen and salts of potassium and sometimes sulfur for these elements. We understand that soil building also includes interdependent relationships between different species of plants, each of which are adding or taking nutrients to and from the soil in a continuous complex cycle. And when you are adding nitrogen to your soil through living plants, you are also adding other life-promoting components to your soil with all the activity that entails. This includes the countless billions of microscopic bacteria and fungi that play such an important role in soil vitality. That kind of activity will never come out of a bag of chemicals. We also want to protect this form of wildlife by not spraying chemical herbicides, insecticides and fungicides, which greatly disrupt and in many cases kill off large populations beneath the surface of the soil. If the soil is dead, it cannot properly nourish the plants that are grown in it.
In the Northern Great Plains, soil building to increase nitrogen is usually accomplished by alternating legume green manure crops with cash crops in the rotations. Most do not have the advantage of having large amounts of manure, compost, seaweed or fish and feather meal nearby. Of course these inputs could be purchased and hauled in, but at great cost. The few hundred dollars per acre return from organic small grains or seed we realize every other year, automatically restricts the amount of inputs we can afford to buy and apply to our fields. Most of us in this region are not grossing tens of thousands of dollars per acre from a fruit and vegetable production. Therefore, growing our own nitrogen and feeding our soil via green manure crops is the best financial solution.
Since most of our soil in this area consists of a rich mixture of minerals delivered to us by glaciers, grinding up the rocks as they moved, as well as a rich diversity of soil from the north, most of the important minerals necessary for good crop production are already present and in high levels. However, because of the high pH of our alkaline soils—due to low rain fall and minimal vegetation—many of the minerals present are bound up as insoluble salts. But in an active and viable soil, some of these compounds can be solubilized by high biological action or the microbes I mentioned earlier and made available to plant roots. For example, some plants, such as buckwheat, can solubilize minerals like phosphorous.
In most areas, not many more than 50 cash crops have been grown since the homesteaders first arrived and broke the land about 100 years ago. The most common practice in the region is still to grow a cash crop every second year, unless there is an abundance of stored moisture which can justify planting a cash crop two years in a row. Because so few crops have been taken off this land, there is still a rich supply of minerals present in the soil. But there will certainly come a time when these minerals begin to be depleted and then serious attention will need to be paid to adding them in the form of soil amendments.
In the Northern Great Plains water is our most limiting factor, so the next part of our in-depth exploration of the second principle of organic agriculture will address that concern with an introduction of green manure crops.