Evaluate CRP land with ‘open eyes’ before converting to organic
By Gary F. Zimmer, Otter Creek Organic Farm
Converting land from CRP into pasture or crop production can be a good way to increase your usable acres—just don’t assume that the land which has been “resting” for a number of years will be highly fertile. Since it is often recommended to rest cropland, or leave it fallow, as a way to improve soil quality, people can assume that leaving land out of production for many years, as in a CRP situation, would mean that land will have great soil structure and be very productive. That could be true, but, in most cases, it takes a lot of work to return the land to a productive state.
Here at Otter Creek Organic Farm, we have taken land out of CRP and converted it to organic production more than once over the past 20 years. To grow good crops we need to improve soil fertility, which by definition is the exchange of nutrients. We spend two growing seasons providing mineral inputs, growing cover crops and getting plant diversity and soil health back in the land. Because of the time commitment, labor, and inputs required to transition CRP land, we prefer to transition land from good conventional farms.
The decline in productivity often seen on CRP land is sometimes attributed to something called “Fallow Syndrome.” This is an observed loss in productivity of land after it has been left fallow for one or more years. One of the problems that can occur after land is left fallow for a period of time is a loss of mycorrhizal fungi. These organisms work symbiotically with plants, bringing them water and minerals, particularly phosphorus, in exchange for the plant providing carbohydrates from photosynthesis. When mycorrhizal populations are low, there will be low colonization rates of plants, which can lead to nutrient deficiencies and poor plant health.
Another downside to leaving land in CRP is that nutrients become tied up in woody plant materials and organic matter and are not cycling as quickly. Often there’s not as much nitrogen cycling, especially if the CRP land is not particularly high in legumes.
There are a lot of things to consider when returning land to production after being in CRP. As long as you go into it with open eyes and a good understanding of what steps need to be taken to move that land into production, it can be a profitable venture.
First, take a soil test. Soil fertility may be low on CRP land. Sitting idle does not induce the soil to release plant-available minerals. A lot of the nutrients on that land are tied up with complex carbons in the woody, brown, or mature plant materials growing there. You need to take a soil test so that you have a good understanding of what minerals may be deficient so you can address those deficiencies.
Second, work the land and begin the process of residue breakdown well before planting. Start working CRP land in the fall. Shred the residues, disk, rotovate, then wait a few weeks and shallowly work the soil and plant a green manure crop. All that brown carbon is complex in structure and slow to digest. Think of it like feeding straw to livestock—straw works better as bedding than feed; and, the CRP land already has enough ‘bedding.’ So apply rich manure, such as poultry, hog or livestock yard manure. Work the land, put manure on it and grow a green, highly digestible cover crop. Fall rye is a good choice for CRP land, especially when planted in the fall.
On the flip side, all that complex carbon from above-ground and below-ground plant materials is good for building organic matter. You don’t want to burn off all your carbon by overtilling. Work the land just enough to break up the sod. Then use your cover crop as a way to start improving soil structure and cycling nutrients.
Third, address any mineral deficiencies. We always start fixing a soil using calcium and phosphorous correction and applying a good, balanced, organic crop fertilizer. It will take some time to get soluble nutrients moving again on CRP land, and rock phosphate and lime are also low in solubility.
Fallow Syndrome can be addressed by adding an extra dose of soluble nutrients at the beginning of the growing season to make up for reduced accessibility of nutrients when mycorrhizal fungi are absent or in low numbers. On an organic farm, the best way to do this is by adding manure or by growing legumes such as soybeans which are less affected by Fallow Syndrome.
Fourth, consider what to plant. A soil full of brown carbon won’t grow the best grasses since they need soluble nutrients. If this option doesn’t exist, then what? We have planted oats and peas in the spring, worked them back in shallowly, then planted a fall seeding crop with clover under-seeded. This is after we made the mineral corrections. We are essentially transitioning the land back into production, as compared to transitioning conventional to organic. We are speeding up and getting the nutrient flow working. Both CRP and conventional land need a healing, fixing period.
Many farmers think it is a good idea to grow perennial hay on CRP land. Growing hay and selling it drains soils of minerals and organic matter. These nutrients need to be replaced through the use of livestock manures, fertilizers, compost, and liming materials. Selling hay from ground with low fertility makes the situation worse.
Converting CRP land to grazing often makes low-quality pasture. Even if you’re not planning on returning your CRP land to crop production, it is important to take a soil test and apply missing minerals.
I don’t want to make it sound like you should be looking at this ‘gift horse’ of already certifiable land in a negative light. I just want you to be aware of the challenges that you may face.
One method I hear farmers say they like is plowing up CRP land and planting soybeans. Soybeans, being legumes and a biological crop, don’t need as many soluble nutrients. If you take this route, make sure that you inoculate the seed with Rhizobium—you do need nitrogen from somewhere.
Usually CRP fields are almost weed-free. Many beginning organic farmers say this makes weed control easy on converted CRP land. However, there are always some weeds, which means there are fresh weed seeds. And with all the tillage, you will destroy soil structure if you keep working the ground, making it more prone to weeds.
I hope this article has helped you think about what’s required to transition CRP land into productive cropland. Start this process with a realistic view of what you’re getting into. Organic farming is taking care of the land; it’s “clean” farming— clean air, clean water, and clean, nutritious, mineral-rich crops. That’s why people support organic production and are willing to pay a premium price for what we grow.
Gary Zimmer heads Midwestern Bio-Ag Products & Services, a manufacturing and consulting company that provides products and services for sustainable agriculture. He is also an on-farm consultant and manages the company’s learning center and Otter Creek Organic Farm.
Leilani Zimmer-Durand, Director of Research at Midwestern Bio-Ag, contributed to this article.
January | February 2014