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This week's Book of the Week feature is Organic No-Till Farming, by Jeff Moyer.
Chapter 2: Whole Farm Planning for Your Transition to Organic No-Till
Organic no-till systems can help you manage a number of important factors, such as soil nutrients, weeds, pests and disease, energy and even your time. However, there are a few considerations to take into account before you get started.
Organic no-till depends on cover cropping for weed management, but it can also help substantially with nutrient management. Your crops’ nitrogen needs can be addressed through the inclusion of legumes in your rotation. And because the soil’s organic matter stores nutrients in a bio-available form, you will be building a store of nutrients that will last for years to come. Fertilizers, compost and manure will be more difficult to incorporate and may need to be applied at alternate times when tillage fits into the rotation. On fields you plan to no-till, manure or compost can best be applied in the fall when the cover crops are planted. This might lead to manure management concerns during the winter and spring. This is an opportunity to plan around the system’s limitations. You might consider composting as a way to store your manure in a more stable form. Let’s take a look at more detailed information on how organic no-till will affect your nutrient management.
Decrease nitrogen leaching
The peak leaching season is during the late fall to early spring, when the surface of the soil is most often left bare. With organic no-till, the soil surface is almost always covered. Rye is an excellent nitrogen scavenger, and keeps it immobilized for later use by cash crops. Cover crops also improve infiltration of rainwater, resulting in greatly reduced leaching.
Increase naturally produced nitrogen
Nitrogen in the organic no-till system comes not only from cover crop legumes in the rotation, but also from the biological decomposition of fresh residues and soil organic matter. By using legumes in the rotation (hairy vetch, peas, annual clovers or another legume), these systems can sequester tremendous amounts of nitrogen. The losses commonly experienced with chemically based nitrogen sources, are greatly lessened by using slow release, biologically sourced nitrogen. Once the soil organic matter is built up, little supplemental nitrogen, if any, is needed in these cover crop-based no-till systems. At the Rodale Institute, our only other source of nitrogen for our grain production fields comes from an application of compost once every five to seven years at the rate of 10 tons/acre, and from alfalfa hay in the rotation. This enables farmers to cut costs on purchased inputs, whether they are using conventional or organic fertilizers.
But here’s the caveat: if you are transitioning to organic production, you may need to add supplementary fertilizer at first in order to get things going. If your soil organic matter is high you may need little or no supplementary fertilizer. If your soil organic matter is lower, you may need to supplement, especially at certain times of the year. Multiple applications are better than a single, early season application. Ron Morse, of Virginia Tech, who works with no-till vegetables, recommends sidedressing with feathermeal as well as fertigating with fish fertilizer or kelp to get these high value crops started.
Enhance phosphorus and potassium availability
Cover crops can pull nutrients, such as potassium and calcium, up from deeper soil layers, which increase their availability for cash crops. Cover crops can also make phosphorus more available and prevent leaching.
Slow release of nutrients
In these cover crop-based no-till systems residues are from mature plants. Consequently, some (like rye) are higher in carbon than in nitrogen. They are also not tilled into the soil, where they would more readily decompose. The cover crop residues then take time to break down, which means a slow release of nutrients, and longer-term weed management from the mulch.
Food source for microorganisms
No-till provides an ongoing feast for microorganisms, by providing fresh decomposing residues year round. It also offers undisturbed habitat and refuge for the microorganisms. Since green living roots are in the soil for a large percentage of the year, arbuscular mycorrhizal fungi flourish in these systems. Arbuscular mycorrhizal fungi enable your cash crops to forage for nutrients and water more effectively, because they double or triple the plant’s root zone. We’ll discuss this in greater detail later in the book.
The cover crop plantings add complexity to the crop rotation, which helps with nutrient management, breaking of pest and weed cycles, building both the content and quality of soil organic matter, and improving the bio-diversity of your soil.
Less time spent in the field tilling and cultivating means more time spent on other projects you need to get done — and there’s always a long list, right? Perhaps you could spend more time marketing your products. Or you could spend more time on equipment maintenance, reducing the risk of breakdowns in the field. However, until you have several seasons under your belt as a no-till farmer, you may spend more time initially on building your skills. Here are some ways that no-till can save you time.
Instead of several field operations for tillage, planting, cultivation and harvesting, organic no-tillage generally requires only one pass through the fields for rolling and planting, and one pass for harvesting. Up to 60 percent fewer person hours are used with no-tillage systems compared with tillage. Organic no-till also offers flexibility in terms of harvest windows. With the high amount of residue from the killed cover crops you’ll be able to get back into the fields more quickly after a heavy rainfall. The residue soaks up water like a sponge, improves infiltration, and slows runoff. Since the soil structure is improved it will stand increased traffic with less compaction and structural damage. This is true whether the harvesting is a machine operation or done by hand. Imagine harvesting pumpkins or tomatoes while walking on a thick mat of rye instead of bare soil.
You may also spend less time irrigating, due to the improved water-holding capacity of the soil, and reduced evaporation. An improvement in soil structure can bring an improvement in your crop’s root system, allowing it to access water more effectively. A general rise in soil organic matter will help with water management as well. These same mulches that suppress weeds will prevent evaporation of water from the soil by protecting the soil from the sun. At the same time, any rain that does fall will be captured within the mulch allowing it to slowly percolate into the soil profile. In some situations the cover crop may actually increase the need for irrigation. For example, in arid climates where irrigation is the primary source of crop production water you may need to rethink your irrigation habits. Cover crops will need valuable water to germinate and grow. Some cover crops pull water out of the soil (such as rye) while others hold moisture in the soil (legumes).
With less machinery, you’ll spend less time on maintenance. The roller/crimper is designed to be low-maintenance with fewer bearings and places where cover crop residue can collect and jam. In fact, it is our experience that a fresh coat of paint every few years is all our roller/crimper needs. However, the planting equipment must be well maintained since it is required to perform under difficult conditions.
We know from decades of garden experience, mulches can be utilized to prevent annual weeds from germinating. We also know that we need to use thick heavy mulches if we want season-long protection from weed infestation. Until now it has been impractical to mulch large acreage due to expenses of time and materials. But by growing the mulch right in the field and using state-of-the-art planting equipment we’re now able to accomplish this feat with ease, saving both time and money over conventionally tilled systems.
Since crops have a mulch of killed cover crop around them, weed management is considerably easier in a no-till system. In contrast, a conventional till system without a mulch layer, will have many weeds that germinate and grow right along with your cash crop. Weeds will be found uniformly distributed through the entire field. The ones between the rows can be removed or buried by cultivation. However, in-row weeds are difficult to remove.
By contrast, in an organic no-till system weeds will generally be found between the rows rather than in the row. This reduces the competition between crop plants and weeds. The few weeds that emerge from the cover crop mat will grow fast and large, making the field appear weedy. Sometimes (depending on the crop) farmers will want to hand weed their fields to provide better control, and to keep any escaping weeds from going to seed.
Also, without the constant soil disturbance found in the conventionally tilled system, there is less movement of weed seeds in the soil profile. They tend to stay on the surface where they are less likely to germinate and are vulnerable to predation or weathering. However, nature is quick to react to any changes we impose on her. As tillage is reduced there may be a shift in the dominant weed species, from fewer annual weeds to more perennials. Systems that are dependent on chemical herbicides tend to generate resistant weeds, which can cause serious problems. On the other hand, organic no-till and rotational tillage relies on a natural system of checks and balances that keeps weeds manageable in the long term. For this reason we still use tillage in our systems at Rodale Institute to prevent perennial weeds from getting a foothold.
The weed management you’re able to achieve with organic no-till partially depends on the residual allelopathic effects of the cover crop. Rye, sorghum-sudangrass, oats and barley are some of the cover crops with the highest allelopathic effects. Although the chemical compounds that cause the allelopathy are strongest in growing plants, they persist in the killed residue for several weeks until they leach into the soil and are broken down by microorganisms. Meanwhile, they provide weed management when the cash crop is at its most vulnerable stage. Allelopathic effects from cover crops can eliminate the need for a post-emergent herbicide. Cover crop varieties can vary widely in their allelopathic effect. The cultivars ‘Bonel’, ‘Maton’ and ‘Elbon’ were found to be the best rye cultivars for allelopathic use.
According to the Rodale Institute’s integrated weed management farm trials, there are substantial differences in how corn and soybean varieties tolerate weeds. In experiments done in 2003-2004, corn yield differences between hand weeded and non-hand weeded areas ranged from 0-46 bushels/acre. Weeds did not affect some varieties at all, while others suffered losses of up to 60
Pests and diseases
As you transition to organic no-till, pest populations will shift as well. Some pest populations will decrease, and in some cases will get worse, depending on your situation. With more surface residue, some pests like slugs or cutworms can become a problem. However, with greater crop diversity, additional habitat, and fewer chemicals, beneficial insects may take care of most of the difficulty. Rye, and especially vetch, are cover crops that encourage beneficial insects. You might manage the problem by including hedgerows and permanent habitat for these beneficials so that they have a refuge during the crop transitions.
About the Author:
Jeff Moyer has been working in the field of organic agriculture all of his adult life. Over the past 28 years he has been the farm manager/director for the prestigious Rodale Institute located in Southeastern Pennsylvania. He currently chairs the United States Department of Agriculture’s National Organic Standards Board and serves as an advisor on organic issues to the Secretary of Agriculture. Jeff is also a founding board member of Pennsylvania Certified Organic, a private non-profit certification agency.
Also by Jeff Moyer:
Titles of Similar Interest:
- The Organic No-Till Farming Revolution: High-Production Methods for Small-Scale Farmers, by Andrew Mefferd
- The Ultimate Guide to Soil: The Real Dirt on Cultivating Crops, Compost, and a Healthier Home, by Anna Hess
- The Ultimate Guide to Natural Farming and Sustainable Living, by Nicole Faires
Other Excerpts to Enjoy:
- Book of the Week: Foundations of Natural Farming
- Book of the Week: Albrecht on Soil Balancing, Vol. VII