Crop Rotation: 7 Steps to Enhance Your Soil Life

By Chad King

Crop rotation has been used since Roman times to improve plant nutrition and to control the spread of disease. A study published in Nature’s The ISME Journal reveals the profound effect crop rotation has on enriching soil with bacteria, fungi and protozoa.

Crop rotation simply means changing the type of crop grown on a particular piece of land from year to year which includes cyclical and non-cyclical rotations. Good crop rotation includes planning ahead two or more years. A lack of planning can lead to problems including the buildup of soil-borne diseases or imbalances in soil nutrients and an increase in pests.

“Changing the crop species massively changes the content of microbes in the soil, which in turn helps the plant to acquire nutrients, regulate growth and protect itself against pests and diseases, boosting yield,” said Professor Philip Poole from the John Innes Centre.

Soil was collected from a field near Norwich and planted with wheat, oats and peas. After growing wheat, it remained largely unchanged and the microbes in it were mostly bacteria. Crop rotation by growing oat and pea in the same sample caused a huge shift toward protozoa and nematode worms.

rotational advice 2

Seven Crop Rotation Steps

A good crop rotation plan should include the following steps:

Step 1. Identify and prioritize your goals. Your goals may to be build better, healthier soils, control pests, minimize soil-borne diseases, reduce weed pressure and to produce the most nutritious foods possible.

Step 2. Write down the mix of fruits, vegetables and cover crops that you plan to grow next season along with each crop’s planting and harvesting dates.

Step 3. Write the plant’s family name next to each crop and then add up the amount of garden space in square feet that will be allocated for each family. If one family will be grown on more than 25 percent of your garden, then consider increasing the diversity of your crop mix. Having a high proportion of your garden in one family might mean that a location will rotate back to that family too soon, which can lead to soil-borne diseases.

Step 4. Make a crop rotation planning map. Think about how you will divide your garden into small units of somewhat equal sizes. These units could be long rows or individual beds of any shape. Making this map and having your garden divided into these units allows you to keep track of what you planted on a piece of ground years later. The map of your garden will show every unit. The map should be large enough so that information can be written inside each unit. For this mapmaking, 12 x 16 sketch paper or a computer works well. When you are done making your map and before you start filling in each unit’s information, make at least six to eight copies. Next, assign a color for each plant family, cover crop, mulch and fallow periods.

Step 5. On another copy of your map, designate each crop to as many units as you need to meet the area of your specific crop mix. If a unit will be double or triple cropped, separate their names with dashes such as May lettuce-buckwheat cover-fall spinach. If you plan on growing two or more of the same crop family on a unit, use slashes to indicate this (tomato/peppers/potato). When placing a crop onto a unit, try to pair crop families together on a given unit, but avoid placing a family onto a unit that has had that same family on the unit in the previous few years. At this time you may match the colors you’ve chosen for families and color them onto the appropriate units.

Step 6. Once you have your maps finished with the crops written inside each unit, numbered and colored, along with any other usable information, then take your maps and walk your garden. Imagine how it will look and consider the tillage, planting, care and harvesting of your crops and if the proposed crop sequence makes sense for a given location. At this time also take into consideration equipment, irrigation and labor needs.

Step 7. Develop a backup plan by thinking ahead to any problems that may arise with growing a crop within a unit, such as if a spring may be too wet for early planted crops or certain transplants are unavailable at a critical time or who will take over your labor duties if something happens to you and you have to be away for an extended period of time. Write down your backup plans for coping with various problems and make provisions for these possible problems.

Every garden is unique and each gardener will have their own specific needs, but there are principals and general rules of thumb that should be followed when thinking about a new rotation.

  • Follow legume cover crops such as clover with high-N demanding crops.
  • Grow winter-killed cover crops before early-season crops.
  • Never grow any crop after itself.
  • Use crop sequences that promote healthier crops such as cabbage family crops following onions or potatoes following corn.
  • Avoid growing one heavy feeder after another heavy feeder.
  • Grow tomatoes after peas, lettuce or spinach, because tomatoes take a lot out of the soil.
  • Grow beans after sweet corn to rebuild nitrogen levels.
  • Use a cover crop’s residue to help build organic matter levels.
  • When growing a wide mix of crops, try grouping into units according to plant family, timing of crops planting dates and harvesting dates.
  • A minimum return time of a crop should be in the four-to-five year range, which often prevents most soil-borne diseases.
  • Attempt to keep something growing throughout the year, which keeps the ground covered, protecting the soil and at the same time will supply organic material for earthworms and beneficial organisms living within the soils. Incorporating cover crops into a rotation makes this possible.

Rotations are an important part of any gardening system. Yields of crops grown in rotations are typically 10 percent higher than those of crops grown in monoculture in normal growing seasons and as much as 25 percent higher in droughty growing seasons.

Adding cover crops to a rotation can add organic matter, enhance mycorrhizal numbers, add nitrogen, suppress weeds and nematodes, reduce soil erosion, increases infiltration of water, decreases nutrient loss and attracts beneficial insects.

Planning Crop Rotation in Vegetable Gardens

There is a growing consciousness around growing one’s own food and the reasons for doing so vary from person to person. Tough economic times, high unemployment, rising food costs and a desire to provide one’s family with fresh, super nutritious food are just a few examples.

One fact that remains the same is that gardener’s put a great amount of care, hard work and time into their gardens only to sometimes achieve mediocre results.

The one factor that we have no control over is Mother Nature. Gardening is inherently risky and pests, drought, flooding and wind along with other weather extremes can all destroy a year’s work. A good example of an extreme weather event would be the severe drought of 2012 that stretched across more than half of the United States and the record number of 90-plus days. With many of those days reaching up into the triple digits. The result was scorched crop fields, pastures and gardens. The drought was so extensive that it also created problems concerning producers’ water supplies. Creeks, rivers, ponds, lakes and aquifers had dangerously low water levels, while others completely dried up.

The number of farmers, livestock producers and gardeners who experienced crop and animal losses in 2012 will not only be felt by them, but will be felt by most American consumers. A large portion of our economy depends on agriculture.

Irrigation was a lifesaver in 2012 for those who had systems in place, but even then some farmers and gardeners were still unable to keep up with demand and eventually had to give up in the face of low water supplies and high fuel bills.

Many gardeners who utilized drip irrigation with mulch or a plastic layer had good results and were able to produce an abundant crop within their gardens.

There are many tools and techniques that growers use to grow their food, somethings they have control over, and others not, but one technique often misunderstood and under valued is crop rotations within a garden.

The smaller a garden is and when a gardener is only growing two or three different crops, it then becomes more difficult for a crop rotation to be effective. There are ways in which a gardener can increase his success rates and be extremely efficient and they include using mulch, compost, manure and short-term cover crops.

Name Game

In the world of gardening there are so many names that it can be confusing and intimidating, but a new gardener who does not understand those horticulture names could make the wrong choice of plants for their garden and the crop rotation plan. To become more knowledgeable with these horticulture names stop by your local library and check out a few books on vegetable gardening, use the Internet, ask your local garden center staff or an experienced gardener. Understanding the vocabulary that comes along with gardening and a crop rotation can make the planning easier and gardening in general a lot more enjoyable, productive and successful.

Grasping the True Value of Cover Cropping

Planting cover crops in rotation between cash crops is even more valuable than previously thought, according to a team of agronomists, entomologists, agroecologists, horticulturists and biogeochemists from Penn State’s College of Agricultural Sciences. Research, published in Agricultural Systems, quantified the benefits offered by cover crops across more than 10 ecosystem services.

man in field
Photo by USDA NRCS

Benefits included increased carbon and nitrogen in soils, erosion prevention, more mycorrhizal colonization and weed suppression. Researchers simulated a three-year, soybean-wheat-corn rotation with and without cover crops in central Pennsylvania, which presented agroecological conditions broadly representative of the Northeast and mid- Atlantic regions. The cover crop rotation included red clover, frost-seeded into winter wheat in March, and winter rye, planted after corn was harvested in the fall. The research, funded by the U.S. Department of Agriculture, used simulated management practices, including tillage, synthetic fertilizer use and mechanical weed control.

This report appears in the May 2014 issue of Acres U.S.A.

Cover Crops on the Farm

By Tara Maxwell

Cover crops are increasingly being used by farmers across the country to suppress weeds, conserve soil, protect water quality and control pests and diseases.

The fourth annual SARE/CTIC Cover Crop Survey collected data from more than 2,000 growers from 48 states and the District of Columbia. The survey provides insight into cover crop usage and benefits and explores what motivates farmers to include cover crops in their farm management and soil health plans.

Respondents reported a steady increase in the number of acres they have cover cropped over the past five years. They said the most important benefits of cover crops include improved soil health, reduced erosion and compaction, and increased soil organic matter. Other reported key benefits of using covers are weed and insect control, nitrogen fixation, attracting pollinators and providing deep taproots.

flowering cover crops
A cover crop mix of rye, clover and vetch.

North Central SARE (Sustainable Agriculture Research and Education) and CTIC (Conservation Technology Information Center) sought data on how farmers use cover crops to manage their fertilizer inputs. Growers were asked to indicate their level of agreement with a series of fertilizer-related statements using a scale ranging from 1 (strongly agree) to 5 (strongly disagree). The statement that got the highest level of agreement was “Using cover crops has enabled me to reduce application of nitrogen on my cash crop,” with 134 of 1,012 respondents strongly agreeing and 244 checking “agree.” The statement that had the highest level of disagreement was “Using cover crops has required me to use additional crop fertility inputs over time to meet the needs of my cash crop.”

Cover Crops & Yields

For the fourth year in a row, the survey found yield increases in both corn and soybeans after cover crops (1.9 percent in corn and 2.8 percent in soybeans). According to the survey analysts,

cereal rye growing in a field
various objects of the summer season in the best of this wonderful period

“Those are modest bumps, but they are statistically significant. A new angle of exploration — on the effects of a cereal rye cover on a subsequent crop of soybeans — revealed that a majority (52 percent) responded that their soybeans often or always rise after a cover crop of cereal rye. Notably, 82 percent said cereal rye cover crops helped with weed control. In all, the popular practice of planting cereal rye cover crops before soybeans was validated in this year’s survey.”

While a majority of those surveyed saw no loss in profit, or lacked the data to tell, about one-third found a profit increase from cover crops, and two-thirds of the respondents said cover crops helped yields remain steady during extreme weather events.

Cover Crop Mixes & Timing

Cereal rye was the most popular cover species in the survey, followed by radish. However, cover crop mixes were planted on nearly as many acres as cereal rye. More than half of the participants in the survey reported that they started with a single species and “graduated” to mixes, while another 17 percent started with mixes and increased their use of blends. 61 percent of the respondents said they designed their own blends and 22 percent relied on their crop consultant or cover crop seed dealer to help them develop a mix.

Legumes are popular among many cover crop users because they fix nitrogen in the soil, in addition to all the other benefits of covers. Crimson clover led the legume category in average acreage per user, followed by winter pea, hairy vetch, other clovers, cowpea, red clover, other vetches and sunn hemp.

Covers have traditionally been planted after harvesting cash crops. However, many farmers have found that seeding cover crops into growing cash crops can provide a vital head start in cover crop establishment.

Tara Maxwell served as managing editor of Acres U.S.A. magazine for 8 years. She is a graduate of Virginia Tech with a background in journalism and animal science, and has a passion for sustainable farming.

Self-Sustaining Rotations

By Newman Turner

Fertility farming—building the fertility of the soil simultaneously with cropping it—has not been popular, especially in official circles, because, since 1939 maximum production at any price has been official policy. It has mattered little that maximum production of chemically-boosted crops has resulted in diminishing fertility for both the soil and the animal, and an increase in degenerative diseases for the ultimate human consumer. The farmer who has dared to put his future soil-fertility on an equal level of importance with productivity has been in perpetual danger of supervision or dispossession by the Agricultural Committees.

Now real efficiency is at last officially permitted. Production is at last beginning, in official circles, to be related to the cost of achieving it; and soil fertility can now once more become a paramount consideration of good farming.

I am using this rotation in reclaiming old worn-out pastures on my present farm.

In the first year, one end of the field is ploughed or rotated in the spring or early summer, and worked periodically to get it clean and start the decomposition of the old turf.

cattle eating silage
Cattle eating silage from a self-serve pile.

In June or early July, into the broken section of the pasture, Thousand-headed kale is sown with a corn drill in rows seven inches apart. The roller follows the drill and no further treatment is given to the kale. It thrives on the decaying turf and produces a leafy plant of kale which is easily grazed behind an electric fence.

The silage heap is made just over on the unploughed portion of the pasture so that the cows may help themselves to silage and kale behind the electric fence—lying back on to the old pasture.

Kale sown on up-churned old turf is ideal for strip-grazing because the turf prevents the soil from becoming too muddy in the winter.

In the second spring, the kale ground is disced or rotavated and sown with oats and vetches, undersown with a herbal ley mixture or sown direct with the ley after cutting the oats and vetches for silage. Another piece of the pasture is broken up and sown to Thousand-headed kale.

The silage heap moves down the field, once more adjoining the kale section.

In the autumn a second silage heap is made from the oats and vetches sown on the first section of the field, leaving the ley underneath for grazing and/or silage in the following spring.
In the third spring we have the herbal ley on the first section, which may be grazed early and then mown to make a silage heap on the old section of the field. The second section which was kale is disced and sown to oats and vetches, and a fourth section is broken for kale. The silage heap is moved down once more on to the old unbroken pasture.

In the fourth spring the second section adds to the area of ley available for grazing and silage. The third section, kale stubble, is disced, or rotated and sown to oats and vetches, undersown or aftersown with a ley, and the fourth section is broken for kale.

Crop Rotation
This chart tracks crop rotations through the four year period.

This process is continued until the whole field has been broken and sown down to a good herbal ley. In the last year the silage heap will have to be made on one of the new ley sections and the oats and vetches section, which is then the last but one section in the field, is sown immediately after the oats and vetches are cut and gathered for silage, to a winter rye or other winter green grazing crop, undersown with ley if early enough in the autumn (i.e. early September), or to be sown down direct with the last piece from which the kale has been grazed, in the spring.

The immense amount of fertility built into the soil by this system comes in a number of ways.

Firstly, everything grown in the field is fed on the field, so that the field grows its own sustenance, passed through the cows, and dunged back rich in nitrogen, potash, and phosphates, and the trace elements derived from the subsoil of adjoining fields brought up by the herbal ley from which the silage was made. When the new ley sections of the field are also going into the silage on the field itself—then the field begins to regenerate its own fertility from its own subsoil (i.e. minerals and trace elements brought up by the deep-rooting herbs of the ley).

If possible each section of the field should be subsoiled either before the kale is sown or before the oats and vetches are sown. In this way the subsoil is opened up ready for the herbal ley which follows the oats and vetches.

Secondly, there are few crops better than oats and vetches for putting nitrogen into the soil. And this is free nitrogen gathered from the atmosphere by the nitrifying bacteria of the vetches—organic nitrogen—the kind which is best for the young ley which is to follow.

You will have no difficulties in establishing a ley from old pasture where a kale crop and an oat and vetch crop have intervened. The decaying turf has released, by means of the organic acids of decay bringing them into solution, the unavailable minerals which are present in every soil if only they can be released. As I have said elsewhere, given a few leaves of organic matter for anchorage, sustenance, and the dissolution of a minute portion of the rock, nature can grow a vigorous and healthy plant actually on a rock. The criterion of crop growing in any part of the world is nothing more complex than the presence of a little moisture-holding, nutrient-releasing organic matter. In other words the secret of establishing a ley is biological and not chemical. This, then, is the third free source of fertility inherent in this system.

Fourthly, the strip-grazing of the kale concentrates an even surface dressing of dung on to the kale section each year, applied far more thoroughly and evenly than by hand or machine, and effectively incorporated into the top soil by the trampling feet of the cattle themselves. A valuable interval of time intervenes for the action of rain, atmosphere and soil organisms to commence their processing of the dung before it is churned into a rich seed-bed by the disc harrow or rotary hoe.

Silage heap
A close-up of a silage heap on Mr. Turner’s farm.

Fifthly, and perhaps the real center-piece in this jig-saw pattern of fertility, is the self-service silage heap, radiating from all angles of the heap the rich manurial value which the cow is continually depositing as she feeds at the heap, and moves to and from the heap in her journeys to the grass to lie and cud, or to the kale to stand and graze. As the silage heap moves across the field each year this concentration of fertility gradually covers the whole field. But as the greatest fertility is always at the site of the heap, additional value may be obtained by shifting the heap from side to side of the field according to where the less fertile areas of the field may be.

Two additions to this self-feeding, self-fertilizing program—one for the heifers and dry stock and one for the milking herd— are the incorporation into the system of the self-feeding of straw and hay.

A system I first saw deliberately practiced in Eire in 1946 is the building of a hay or straw stack in a field in which cattle are to be wintered, and allowing the cattle to pull out the hay or straw as they need it. By this method they gather from the hay or straw both food and shelter. The small residue, trampled under and dunged upon, is forked up into a compost heap when the cattle have finished.

With cattle that are not in milk, where unlimited straw may be allowed, the combination of this straw-feeding system with the self-fed silage and kale provides a way of using straw and increasing the amount of manure available to spread on the field. One snag, however, is that very little of the straw is eaten whenever there is good silage available, and this even applies to hay. It seems that even the best hay is less palatable than good silage and kale.

Source: Fertility Pastures