Crop Rotation for Diversified Vegetable Operations
Crop rotations are an essential farm tool. If planned and executed well, a crop rotation can establish long term soil health, break pest and disease cycles, diminish weed seed banks, balance nutrient levels, and create a vigorous overall farm system.
Even if you’re a well-established farmer, chances are you’re frequently making adjustments to your crop rotation in order to improve your soil’s health and nutrient balance. High Mowing founder Tom Stearns suggests that crop rotations are a continuum: farm planning involves numerous variables, and as a result it may be impossible - and unwise - to craft a perfectly rigid system.
Here are a few of the most important elements to consider for your crop rotation and tips on how to approach them.
Include cover crops in your rotation. Because cover crops are vastly different from annual vegetable crops, many growers simply cover crop all of their fields the same way at the same time. Cover crops should instead be worked into an overarching crop rotation plan with equal precision and consideration. Working cover crops into your rotation from the start will ensure accurate sowing dates and help balance nutrient levels across all sections of your fields.
High Mowing’s current crop rotation has ~30% of its acreage in cover at all times. This extensive cover cropped land allows for flexibility in the rotation of crops, says Stearns. If an unexpected disease cycle prevents planting certain crop types in a planned area, the cover cropped land acts as a healthy buffer that can be used instead. In other words, having one third of your land in cover means you can cheat by using a little bit of that covered land if you really need to.
Diversify your tillage timing and techniques. Consider when your cash crops are planted in the field and when they are taken out of the field. This will help determine where to break ground first, where to plant spring cover crops, and when and what to sow for fall covers. The depth of your tillage and how frequently you disturb your soil will have a significant effect on its health. Making these plans will also help you increase efficiency with your labor time and tractor use.
High Mowing incorporates “bare fallow” sections into our rotation, which means the soil is planted with neither row crops nor cover crops, but rather remains bare until it is time to plant again. Shallow soil tillage allows the weed seed bank to grow out during times of the year with both warm and cool soils. The High Mowing farmers prefer to use a Perfecta field cultivator to achieve this type of tillage. This technique allows the destruction of millions of weed seedlings in 10 minutes per acre; a feat that simply cannot be accomplished when there are crops in the field. This practice goes a long way towards long-term weed control.
Strive to balance soil fertility. Most growers avoid depletion of specific soil nutrients by rotating crops based on family. As a rule, each family should not grow in the same area for at least four years. If you have the space, dedicate at least one section to fallow land for an entire year or more. The established roots of grasses and perennial legumes build exceptional fertility and organic matter when grown for 1-2 years. This will allow your soil to rest and rejuvenate, while creating space in your crop rotation. Different crops take up different nutrients from the soil, so you may want to consider beneficial crop sequences that can complement each other with nutrient uptake (i.e. carrots and lettuce tend to work well when planted sequentially).
Starting in 2017 High Mowing will operate with a 7-year rotation plan, including two years of fallow sod in each section. With the crop types that we grow for seed production, this allows us to have at least four years between crops of the same family.
Consider pest and disease cycles. One of the most beneficial effects of a crop rotation is the break-up of pest and disease cycles. These cycles are often related to plant family. If you have two or more fields with crops of the same family planted in one growing year, avoid having them planted adjacent to each other. Avoid planting crops from the same family sequentially for at least four years.
High Mowing’s 7-year crop rotation allows for four years between our cucurbit plantings, a family that is often susceptible to disease contamination which is of particular concern for high quality seed production.
Think long term. Some advanced and highly diversified farms might be able to work livestock or some non-traditional crops into their vegetable rotations. Plans that include several annual and/or perennial crops (including wood lots), livestock, and tillage equipment or techniques could be as far-reaching as 10 to 50 years in the future. It all depends on what land is available to you, how committed you are to your market, and what your soil tells you about its health from year to year.
You may be land-rich, which allows for a great deal of flexibility. But, if you are tight on real estate, you should consider strict planning. This can even include the dimensions of bed spacing and driving lanes to maximize your land use without compromising overall system health. We have standardized our field dimensions here at High Mowing, even though we have plenty of land, because we find that uniform field sizes and precise bed spacing help us work more efficiently overall.
It is likely that your plan will need to be adjusted for at least the first few years you implement it, if not every year. The most important thing to remember whether you’re a first time farmer or a seasoned veteran is this: planning your rotation will take time. Do not underestimate the importance of your rotation plan. It may seem like it’s taking you a long time to get every puzzle piece in place, but keep in mind that it is a complex process that deserves due time. Consider creating both a written plan and a visual map of your rotation. Color coding both will help you better visualize crop balance and make appropriate adjustments.
In the end, your fields, crops, and customers will appreciate your diligence when your thoughtful crop rotation produces delicious, nutrient-rich results.
Rodale’s Organic Life (2011), The Key to Keeping a Rich Vegetable Patch
SARE (2009), Crop Rotations on Organic Farms: A Planning Manual
Mother Earth News (2010), Maintain Healthy Soil with Crop Rotation