Posts Tagged ‘soil health’

Using Winter Kill Cover Crops as a Part of Your Vegetable Cropping System

Friday, August 24th, 2012

Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu

Cover crops that will put on significant growth in the fall and then die during the winter can be very useful tools for vegetable cropping systems and the University of Delaware, University of Maryland, and other universities in the region have been conducting research on a number of these winter killed crops for use with vegetables.

Winter killed cover crops that are late summer and fall planted include spring oats, several mustard species, and forage and oilseed radish. Earlier planted summer annuals (millets; sorghums, sudangrasses, and hybrids; annual legumes such as sun hemp or forage soybeans; buckwheat and many others) can also be used as winter killed species. Timing of planting will vary according to the species being used and winter killed species selection will depend on when fields will be available for seeding. Spring oats, mustards, and radishes can be planted from late August through September. Once into October, they do not put on adequate fall growth. Summer annuals should be planted in late July or during August for use in a winter killed system to obtain sufficient growth.

The winter of 2011-2012 was extremely mild and gave us a good look at issues that occur when crops that normally winter kill do not. In our plots at the Georgetown, DE research farm last winter, forage radish, oilseed radish, spring oats, and edible greens type mustard (Tendergreen) did not winter kill completely. All the biofumigant mustards (Pacific Gold, Idagold, Caliente, and Kodiak) winter killed completely (as did summer annuals).

The following are several options for using winter killed species with vegetables:

1) Compaction mitigation for spring planted vegetables. Where there are compacted fields, the use of forage radishes has worked very well as a winter killed cover crop by “biodrilling”. The extremely large taproot penetrates deep into the soil, and after winterkilling, will leave a large hole where future crop roots can grow. Oilseed radish also provides considerable “biodrilling”. Winter killed radishes works well with spring planted crops such as peas, early sweet corn, and early snap beans.

2) Early planted vegetables. A wide range of early planted vegetables may benefit from winter killed cover crops. For example, peas no-till planted or planted using limited vertical tillage after a winter killed cover crop of forage radish, oilseed radish, or winter killed mustard have performed better than those planted after conventional tillage. Early sweet corn also has potential in these systems as do a wide range of spring vegetables. Winter killed radishes and mustards also have the advantage of outcompeting winter annual weeds leaving relatively weed free fields and also in recycling nutrients from the soil so that they are available in the spring for early crops (decomposition has already occurred).

3) Mixed systems with windbreaks for plasticulture. By planting planned plasticulture bed areas with winter killed cover crops and areas in-between with cereal rye you can gain the benefits of these soil improving cover crops and eliminate the need make tillage strips early in the spring. The winter killed areas can be tilled just prior to laying plastic.

4) Bio-strip till. By drilling one row of forage or oilseed radish and other adjacent rows with rye or other small grains, you can create a biodrilled strip that winter kills and that can be no-till planted into the spring without the need for strip-till implements. This opens up dozens of options for strip tilling (seed or transplanted) spring vegetables.

Cover Crops for Vegetable Rotations Revisited

Friday, August 12th, 2011

Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu

August is here and it is time to consider late summer and fall cover crop options for vegetable rotations. Cover crop planting windows vary with crop and timely planting is essential to achieve the desired results. Here are some reasons to consider using cover crops in vegetable rotations:

Return organic matter to the soil. Vegetable rotations are tillage intensive and organic matter is oxidized at a high rate. Cover crops help to maintain organic matter levels in the soil, a critical component of soil health and productivity.

Provide winter cover. By having a crop (including roots) growing on a field in the winter you recycle plant nutrients (especially nitrogen), reduce leaching losses of nitrogen, reduce erosion by wind and water, and reduce surface compaction and the effects of heavy rainfall on bare soils. Cover crops also compete with winter annual weeds and can help reduce weed pressure in the spring.

Reduce certain diseases and other pests. Cover crops help to maintain soil organic matter. Residue from cover crops can help increase the diversity of soil organisms and reduce soil borne disease pressure. Some cover crops may also help to suppress certain soil borne pests, such as nematodes, by releasing compounds that affect these pests upon decomposition.

Provide nitrogen for the following crop. Leguminous cover crops, such as hairy vetch or crimson clover, can provide significant amounts of nitrogen, especially for late spring planted vegetables.

Improve soil physical properties. Cover crops help to maintain or improve soil physical properties and reduce compaction. Roots of cover crops and incorporated cover crop residue will help improve drainage, water holding capacity, aeration, and tilth.

There are many cover crop options for late summer or fall planting, including:

Small Grains
Rye is often used as a winter cover as it is very cold hardy and deep rooted. It has the added advantage of being tall and strips can be left the following spring to provide windbreaks in crops such as watermelons. Rye makes very good surface mulch for roll-kill or plant through no-till systems for crops such as pumpkins. It also can be planted later (up to early November) and still provide adequate winter cover. Wheat, barley, and triticale are also planted as winter cover crops by vegetable producers.

Spring oats may also be used as a cover crop and can produce significant growth if planted in late August or early September. It has the advantage of winter killing in most years, thus making it easier to manage for early spring crops such as peas or cabbage. All the small grain cover crops will make more cover with some nitrogen application or the use of manure.

To get full advantage of small grain cover crops, use full seeding rates and plant early enough to get some fall tillering. Drilling is preferred to broadcast or aerial seeding.

Ryegrasses
Both perennial and annual ryegrasses also make good winter cover crops. They are quick growing in the fall and can be planted from late August through October. If allowed to grow in the spring, ryegrasses can add significant organic matter to the soil when turned under, but avoid letting them go to seed.

Winter Annual Legumes
Hairy vetch, crimson clover, field peas, subterranean clover, and other clovers are excellent cover crops and can provide significant nitrogen for vegetable crops that follow. Hairy vetch works very well in no-till vegetable systems where it is allowed to go up to flowering and then is killed by herbicides or with a roller-crimper. It is a common system for planting pumpkins in the region but also works well for late plantings of other vine crops, tomatoes and peppers. Hairy vetch, crimson clover and subterranean clover can provide from 80 to well over 100 pounds of nitrogen equivalent. Remember to inoculate the seeds of these crops with the proper Rhizobial inoculants for that particular legume. All of these legume species should be planted as early as possible – from the last week in August through the end of September to get adequate fall growth. These crops need to be established at least 4 weeks before a killing frost.

Brassica Species
There has been an increase in interest in the use of certain Brassica species as cover crops for vegetable rotations.

Rapeseed has been used as a winter cover and has shown some promise in reducing levels of certain nematode in the soil. To take advantage of the biofumigation properties of rapeseed you plant the crop in late summer, allow the plant to develop until early next spring and then till it under before it goes to seed. It is the leaves that break down to release the fumigant-like chemical. Mow rapeseed using a flail mower and plow down the residue immediately. Never mow down more area than can be plowed under within two hours. Note: Mowing injures the plants and initiates a process releasing nematicidal chemicals into the soil. Failure to incorporate mowed plant material into the soil quickly, allows much of these available toxicants to escape by volatilization.

Turnips and mustards can be used for fall cover but not all varieties and species will winter over into the spring. Several mustard species have biofumigation potential and a succession rotation of an August planting of biofumigant mustards that are tilled under in October followed by small grain can significantly reduce diseases for spring planted vegetables that follow.

More recent research in the region has been with forage radish. It produces a giant tap root that acts like a bio-drill, opening up channels in the soil and reducing compaction. When planted in late summer, it will produce a large amount of growth and will smother any winter annual weeds. It will then winter kill leaving a very mellow, weed-free seedbed. It is an ideal cover crop for systems with early spring planted vegetables such as peas.

Oilseed radish is similar to forage radish but has a less significant root. It also winter kills.

Brassicas must be planted early – mid-August through mid-September – for best effect.

Mixtures
Mixtures of rye with winter legume cover crops (such as hairy vetch) have been successful and offer the advantage, in no-till systems, of having a more rapidly decomposing material with the longer residual rye as a mulch.

Spring Cover Crops for Vegetable Rotations

Friday, April 8th, 2011

Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu

One principle of managing for improved soil health is that you should always have a crop growing on the soil. This will maintain or add organic matter, provide benefits from the action of growing roots, and recycle nutrients.

Where fall cover crops were not planted due to late harvest, spring cover crops can be planted and provide some benefit where vegetables are not scheduled until late May or June. Cover crop options for early April planting include spring oats, mustards, and annual ryegrass. Plant oats at 90-120 lbs per acre, mustards at 10-20 lbs per acre, and annual ryegrass at 20-30 lbs per acre if drilled. Increase seeding rates by at least 50% if surface broadcast. These cover crops can be no-tilled into soybean or corn stubble.

Spring Cover Crop Managment

Friday, March 11th, 2011

Richard Taylor, Extension Agronomist; rtaylor@udel.edu

Although it seems like ancient history, many years ago when no-till technology was first beginning, Delaware and Maryland farmers were rapid adopters of cover crops for no-till grain production. Farmers mostly used cereal crops as winter cover crops. At the time, we learned some important lessons that we should remember this year because of the weather pattern that has occurred in a number of areas in Delaware.

Because there are a number of perceived environmental benefits with cover crops, government programs, as well as many environmentally-conscious growers have moved production agriculture back into heavy reliance on cover crops. Wheat and cereal rye are two popular cover crops, although some growers are using legumes, legume-cereal combinations, and even some other broadleaf crops such as the forage or Daikon radish. These cover crops are designed to protect the soil, add in organic residues, or supplement the soil with legume-derived nitrogen (N).

For any cover crop, whether it’s the grass cereals used for ground-covering, water-conserving mulch or legumes for spring N-fixation as well as for residue, I have found that there is a tendency to allow these crops to grow as much as possible by delaying herbicide or tillage or other cover crop control method as late as possible. In years when adequate rainfall occurs or good early season rainfall keeps the crop supplied, cover crops are not very harmful to soil moisture reserves or actually may be very helpful in drying out the surface soil. However, the season to be extra cautious in is the year when winter rainfall is below normal and this is followed by a dry early spring. The combination of lower than expected subsoil moisture level and rapid cover crop growth with heavy water use by the cover crop can lead to excessively dry sub-soil conditions.

The latter weather pattern seems to be developing in many areas of Delaware since winter rainfall has been below normal or the ground has been frozen during precipitation events. Growers need to monitor their subsoil moisture levels closely this spring and be prepared to terminate their cover crops earlier than normal if the subsoil becomes too dry. Early termination of the cover crop will allow time for subsequent rainfall to percolate into the subsoil and for the killed mulch to protect the soil from excessive water loss through evapotranspiration.

Growers or their consultants can check the subsoil moisture level with either the standard soil testing probe or with one that has an extended handle to make deep probing physically easier. It still is much of a “feel method” that depends on the experience of the person testing the soil. As a general rule, if subsoil is formed into a ball by squeezing it together in one’s hand and then the hand is opened and the ball easily falls apart with the least touch and no hint of moisture is present on the hand after making the ball, then the soil is on the dry to very dry side. The cover crop should be killed before the subsoil drops to the very dry state.

Biofumigant Mustards for Spring Vegetable Plantings

Friday, March 11th, 2011

Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu

In fields with heavy vegetable rotations that have built up diseases (including nematodes), or fields known to have problems in the past, use of a biofumigant mustard crop planted in March ahead of spring planted vegetables can help reduce disease levels.

Mustard family plants produce chemicals called glucosinolates in plant tissue (roots and foliage). These glucosinolates are released from plant tissue when cut or chopped and then are further broken down by enzymes to form chemicals that behave like fumigants. The most common of these breakdown products are isothiocyanates. These are the same chemicals that are released from metam-sodium (Vapam) and metam-potassium (K-Pam), commonly used as chemical fumigants.

Three mustard varieties that have been successfully used for this purpose are Pacific Gold, Idagold, and Caliente 99.

You should plant these mustards as soon as the ground is fit in March. They take 50 days to produce full biomass. Planting rates are 10-15 lbs/ A for Pacific Gold and 15-20 lbs/A for Caliente 99 and Idagold. Add 40-80 lbs of Nitrogen per A to grow the crop (the higher N level on sandy soils).

The goal is to produce as much biomass of the biofumigant crop as possible. This requires that you have a good stand, fertility, and sufficient growing time. The more biomass that is produced and that is incorporated, the more chemical is released.

The plant material must be thoroughly damaged so that enzymes can convert glucosinolates into isothiocynates. This means that you need to chop the material as much as possible and work it into the soil as quickly as possible, so as not to lose the active compounds to the air. A delay of several hours can cause significant reductions in biofumigant activity. The finer the chop, the more biofumigant is released. A flail mower is ideal.

The material should be incorporated as thoroughly as practical to release the biofumigant chemical throughout the root zone of the area that is to be later planted to vegetables. Poor distribution of the biofumigant crop pieces in the soil will lead to reduced effectiveness.

Sealing with water or plastic after incorporation will improve the efficiency (as with all fumigants). Soil conditions should not be overly dry or excessively wet.

Allow 2-3 weeks after incorporation before planting the next crop.

A March 15 planting will be ready to incorporate in early May and can be planted with the vegetable crop in late May (around Memorial Day).

Crop Rotation Planning and Revision

Friday, September 17th, 2010

Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu

Fall is a good time for vegetable growers to plan or revise rotations. The following are some general thoughts on rotations.

Three years is the minimum rotation for crops in the same family or with similar disease profiles. Five or more years is recommended for vine crops. Field crops such as corn, small grains, and sorghum are good rotational crops. Soybeans may be a good rotation for some crops but not for legumes such as lima beans or snap beans.

Problems often arise where growers increase vegetable acreage without adequate ground for rotation. Base your acreage decisions on available fields that fit rotational schemes.

Where vegetables are the main income for a farm, consider using soil improving crops (green manures, biofumgant crops, soil improving cover crops) in lieu of standard field crop rotations. While some income will be lost on field crop revenues, there will be long term gains with improved vegetable yields.

Where rotations are tight, it is critical to consider some disease reducing crops in the rotation (mustard family and sorghums for example). Try to build up organic matter in these fields as this generally improves overall soil health.

Rotate vegetable families where possible. Do not rotate within a family (such as the bean family, vine crop family, or tomato family). Sweet corn is an example of a good vegetable rotational crop to break up disease cycles on many farms.

Managing Compaction on Pastures when Soil Moisture Content is High

Thursday, May 6th, 2010

Richard Taylor, Extension Agronomist; rtaylor@udel.edu

During the rather warm weather of this past weekend I spent a couple of relatively uncomfortable nights when our new air conditioner wouldn’t start. Although this can hardly be called earth shattering news, it did bring to mind how we all seem to have forgotten the days when AC was not available and wasn’t built into our tractors as standard equipment. Following the uncomfortable weekend, I was asked if it is important to consider how wet some pastures or areas of pastures are when choosing the tractor to use when dragging a chain drag across the pasture to break up manure piles. Although we might be tempted to use whatever sized tractor we have that has AC and all the comforts of modern equipment, it is important to keep in mind that we should use only as large and heavy a piece of equipment as is necessary to complete the job. In the case of dragging pastures to spread manure piles to prevent the piles from killing the grass/legume beneath them, a small tractor or ATV capable of pulling the chain drag is all that is needed.

Although grazing animals can contribute to compaction issues, I think it is good management to minimize all other sources of compaction. Mowing recently grazed pastures or dragging them to redistribute the manure are excellent practices in their own right. Mowing leftover spring grass removes seed heads and stimulates the grass to produce new vegetative tillers that are high in nutritive value. Spreading manure helps it to dry out and get into contact with more soil surface area to encourage rapid decomposition. Dragging manure spreads the nutrients over more land area and removes manure piles that can suffocate or shade out the underlying grass creating space for weed encroachment. When piles are not broken up and distributed around the pasture, animals selectively graze away from the grass in and around the pile causing reduced utilization of the pasture.

Choosing to use the biggest and perhaps newest heavy duty equipment can make the job of mowing or dragging pastures more tolerable but in the process of doing a good management practice you end up cancelling all the good you will be doing by causing more compaction problems, especially in the wetter areas of a pasture. Compaction, and especially deep compaction issues, are very difficult to resolve without a total pasture renovation in which the pasture is deep ripped, tilled, and replanted. Compaction issues tend to be cumulative until poor productivity or weed competition becomes severe enough to demand a solution — total pasture renovation. So, take out the sun screen or pull on a large hat, wheel out the four wheeler or one of the older, smaller tractors and avoid more compaction!

On Farm Adoption of Soil Health Practices as a Part of Integrated Pest Management for Vegetables

Thursday, April 29th, 2010

Gordon Johnson, Extension Fruit & Vegetable Specialist; gcjohn@udel.edu

Vegetable crops are susceptible to a number of soil borne pests. In particular, soil borne diseases such as Fusarium in vine crops and solanaceous crops, Rhizoctonia in bean crops, Sclerotinia in bean crops, Verticilium in solanaceous crops, Pythium in most vegetables, and Phytophthora in vine crops, solanaceous crops, and bean crops have major impacts on the productivity of important vegetable crops in Delaware . Nematodes are also an issue on many vegetable crops in the state (root knot on many vegetables, lesion on potatoes as examples). Current control practices include fumigation and the use of soil applied fungicides or nematicides. However, the most effective control is the use of long rotations with non-host crops. This has been the standard extension recommendation to reduce the economic impact of these diseases and reduce the need for chemical controls. Long rotations are difficult to achieve on many farms due to land limitations. This problem has been worsened by the pressure of development and the decrease in farmland for rotations.

Insects and slugs in soils are also issues in many vegetable crops that affect overall plant heath. Often, as with the case of seed corn maggots, cutworms, and slugs; practices that are recommended to improve soil health – such as use of cover crops and no-till planting in vegetable production – can increase problems with these pests. This limits the adoption of these practices.

A major limitation to overall plant health in Delaware vegetables is soil compaction. Not only does compaction directly affect root growth, it also leads to increased problems with soil borne diseases as compacted soils often stay wetter for longer periods. In processing vegetables, harvest schedules often necessitate the use of heavy equipment and trucks when soils are wet, leading to extensive, deep, and long term compaction problems. Soil health is compromised and performance of future crops is affected.

Weed competition is another important issue in vegetable production. Management of the weed seed bank in soils can be a challenge and should be considered in an overall soil health program. Many vegetable crops have limited herbicides available to manage weeds and there has been an increase in the number of herbicide resistant weeds. Notably, herbicide resistant pigweed is a major problem in Delaware vegetable production. Adoption of soil health building practices such as the combination of cover crops with no-till and strip-till vegetable production is often limited by these weed control challenges. Weed control in organic vegetable production has also been a major problem limiting organic acreage.

Overall vegetable plant health is greatly affected by plant nutrition and soil fertility. Delaware requires nutrient management plans on all farms. Part of this planning process is how to incorporate best management practices to reduce nitrogen (N) and phosphorus (P) losses. Manure and compost use needs to be balanced against vegetable crop requirements and existing soil levels (for P) often limiting applications. On the other hand, practices benefiting soil such as the use of winter cover crops are encouraged as they can recycle nutrients (N primarily) that would be otherwise lost. While not directly related to management of a specific pest, decisions related to soil fertility and nutrient management will have implications for soil health in general, and therefore needs to be included in soil health and IPM program for vegetables.

Water management is directly tied to practices that influence soil health and vegetable crop performance. This includes ways to increase water holding capacities of soils; and at the same time, how to maintain good drainage and aeration. Improving soil water holding capacities will reduce vegetable plant stress and improve overall plant health. In addition, water management is linked closely with many soil borne pests, particularly in relation to drainage, with disease organisms such as Phytophthora being a major problem with vegetables in poorly drained soils in Delaware.

There has been a renewal of interest in soil health in relation to vegetable production in Delaware especially where tight rotations are an issue. Fortunately, there has been considerable research related to cover crops, green manures, compost, organic matter, and rotations in the past 10 years and there is ongoing research in the region on the effect of different rotations and species to improve soil health and reduce soil borne pests. Vegetable cropping systems that incorporate cover crops with no-till production or that have limited tillage have also been studied in the region. Other research in the region on cover crops that can reduce soil compaction is of great interest. There has been research on soil nutrient and water management for vegetable crops but limited work on how these areas intersect with soil health. Delaware vegetable growers, large and small, can benefit by adopting specific practices that improve soil health and by incorporating these practices into an integrated pest management programs for their farms.

Starting in 2009 and continuing into 2010, there has been a coordinated educational effort in Delaware on soil health as a part of integrated pest management for vegetables with field demonstrations, classroom sessions, publications, and on-farm training sessions. This initial effort emphasized how to evaluate overall soil health on a farm, the use of compost, general cover crop and green manure crop use, and biofumigant cover crops use.

We will be continuing these extension programs on soil health as a part of vegetable integrated pest management (IPM) programs over the next 3 years. In this effort we will expand educational areas to include soil disease management, soil insect and slug management, soil compaction management, weed management, soil fertility and nutrient management, and soil water management as part of an overall soil health and IPM program for vegetable crops. The emphasis will be on the on-farm adoption of soil health practices.

We are seeking 20 vegetable farmers as potential cooperators, targeting farms that are experiencing soil health problems and that have tight vegetable rotations. Plans to improve soil health in problem fields will be developed working with each farmer. This will include recommendations for rotations, cover crop use, green manure use, compost use, manure use, other organic matter additions, biofumigant crop use, and tillage practices. These prescriptive plans will be implemented by each farmer and the effectiveness of suggested actions will be evaluated at the end of 3 years by using soil health assessment tests (before the program starts and after 3 years). The economics of using these methods will also be assessed.

Delaware growers interested in participating in this program should contact Gordon Johnson, Extension Vegetable and Fruit Specialist, University of Delaware gcjohn@udel.edu, (302) 856-7303 office or (302) 545-2397 cell.

Considerations Following a Wet Year

Thursday, April 8th, 2010

Gordon Johnson, Extension Fruit & Vegetable Specialist; gcjohn@udel.edu

From the spring of 2009 through the winter of 2010, we received record amounts of precipitation. The following are some considerations for vegetable production following a wet year.

● Check your pHs. The pH of soils during wet years often drops more than in normal periods. Be most concerned where fields have a “borderline” overall pH in the 5.7-6.0 range. Often there will be areas in those fields with much lower pHs. Specifically check your sandiest areas, which leach the most, and headlands where there may be overlaps in nitrogen application (ammonium and urea fertilizers drop the pH). These areas may have spots with pHs well below 5.5. You should also check the pH of areas in the field that were wet or waterlogged. Wet field areas initially drop in pH due to fermentation of organic matter by microorganisms in anaerobic conditions as well as an increase in carbon dioxide dissolved in the soil water forming a weak acid. However, the pH may subsequently rise in flooded soils due to reducing bacteria which consume the acidifying hydrogen. When these areas dry out, they may drop in pH again due to several soil processes. Therefore it is hard to predict the pH of wet areas and separate samples should be taken after they have drained.

● Take time to note and mark out drainage problems and take measures to address them. Drainage problems in fields can have severe impacts on vegetable crops through waterlogging that limits oxygen for roots and through increased activity of soil borne pathogens that thrive in wet conditions. This past year offered the “worst case scenario” and drainage issues are obvious. Use this information for planning purposes.

● Nitrogen carryover this year is minimal and should not be counted on. Fields with no cover crops or poor stands of cover crops will provide very little recycling. Nitrogen recommendations will have to be modified accordingly.

● Compaction from a number of sources is evident in many fields. In particular, rutted areas from field crop harvest operations last fall will need to be addressed with targeted tillage this spring.

Late Summer and Fall Cover Crops for Vegetable Ground

Friday, August 28th, 2009

Gordon Johnson, Extension Ag Agent, Kent Co.; gcjohn@udel.edu

Vegetable growers should make plans to put in late summer or fall cover crops after summer vegetables are harvested. Cover crops help to maintain organic matter, recycle nutrients, reduce compaction, and maintain overall soil health. These benefits far outweigh the cost of establishing the cover crops.

The following are some cover crops to consider:

Winter Annual Legumes
These cover crops will produce significant biomass (organic matter) and, at the same time, provide nitrogen for the following crop through biological nitrogen fixation: hairy vetch, crimson clover, field peas (winter peas). Hairy vetch makes an excellent mulch for no-tilling vegetables into. Plant by September 30.

Small Grains
These winter annual grasses will provide significant biomass, recycle nutrients (especially nitrogen), and produce excellent mulch for no-tilling vegetables in the spring: rye, triticale, wheat, barley, winter oats. Spring oats can be used where you want to get fall cover but need the crop to winter kill for early spring vegetable crops. Plant by the end of October.

Mustard Family Cover Crops
These include both fully hardy overwintering species and species that will winter kill. They provide significant organic matter, recycle nitrogen, can reduce compaction, and offer the potential for biofumigation. Plant by September 15. Included are:

Rapeseed and Canola – overwinter and are good biofumigants

Forage Radish, Oilseed Radish, and Daikon Radish – very good for reducing compaction in soils; forage radish winter kills, oilseed radish is more hardy

Mustards (brown and yellow mustards as well as garden mustard) – offer good biofumigant potential; half hardy

Turnips (forage and garden types) – good biomass production; half hardy

Kale (forage and garden types) – winter hardy; good biomass production

Hybrid Forage Brassicas (such as ‘Typhon’) – these are hybrid crosses of two or more species that will produce excellent fall growth and some will overwinter

Annual Ryegrass
This winter annual grass offers easy establishment, even when overseeded, and puts on significant fall and spring biomass. It scavenges nitrogen and is a quick decomposer in spring. Plant by October 15.

For seeding rates, contact you County Extension Office.

It is often advantageous to plant several of these cover crops together and most will mix well. Use the planting deadline for the species that has to be planted the earliest. Reduce the rate of each component in the mix by 1/3 to ½. I particularly like a rye-hairy vetch-crimson clover mix.