NO-TILL GARDENING & COVER CROPPING

No-till corn planted into a cover crop of cowpeas.
 Photo by Dr. Rafig Islam, OSU

Sometimes when you start thinking about something, that "something"   triggers  a  sense of confusion before you realize that the "something" that appeared simple is actually, like most things, quite complicated.

Confusion was my   first reaction when I started to think about how  no-till gardening related to cover cropping. I know that master gardeners preach about them  and farmers regularly use cover cropping to improve aspects of soil fertility and structure; but the two ideas also seemed to be somewhat contradictory top me.  

Mowed cover crop in spring. The  decomposing green  provides a mulch layer

while the roots    improve aeration as well as add  nutrients as they decay.

The idea behind no-till is that soil fertility and structure are improved by allowing the  soil's ecology to develop naturally with little or no soil disturbance.   No-till practices allow the populations of earthworms, bacteria, nematodes and, importantly, mycorrhizal fungi to increase in the soil   establishing a balanced ecology that sustains soil fertility.   Mulch and compost are typically put on top of the soil to augment any needed nutrients and to suppress the sprouting of weed seeds     arriving via the wind or bird droppings.

Traditional plowing [a deep tillage technique], as well as a gardener's   deep spading, destroys many of these healthy soil organisms; and this means, in the case of mycorrhizal fungi,  that plants will actually miss out on obtaining the water and nutrients  these critters  can also  provide to plants.  Dormant weed seeds long buried in the ground may also be moved up to the surface and  be stimulated to sprout when  exposed to daylight.    But, there are also  positive aspects of deep tilling to keep in mind.  It does introduce oxygen into the soil  quickly and that  stimulates bacteria to breakdown available organic matter releasing some nutrients in usuable form, like nitrogen, for a new crop.  It also  expedites the warming  and drying of  soil in the spring enabling earlier planting.  Over time, however, deep tilling can lead gardeners and farmers to   become more dependent on commercial fertilizers, herbicides and pesticides to compensate for   a depleted  soil ecology.

Backyard gardeners using raised beds or containers probably unconsciously incorporate a lot of no-till practices  into their garden chores, and  many of these gardeners also  use of cover crops.    The backyard gardeners, I know, mostly limit their cover crops to winter rye or buckwheat at the end of a growing season as a way to give their soil a nitrogen shot  next season because both of these cover crops  can be lightly tilled into the soil top few inches of  soil or easily mowed/rolled down without disturbing soil ecology.

FWIW:  Legume cover crops, like cowpeas, take nitrogen (N) from the air and convert it to ammonium,  and then this new N source  potentailly becomes  available to  plants in the spring. Non-legume cover crops recycle any leftover N in the soil from a prior harvest. This N  becomes available to new  plants as the roots of the cover crop decompose. But, take note, because soil microbes usually become active before new plants,  the microbes  get first dibs on available N.  If a soil's N content is low in the spring, new plants may encounter a  deficiency of N. This can happen if spring planting gets delayed by weather - the soil is too wet, too cold etc.

So, who wouldn't want to use cover crops?

Plowing  warms  and drys  soil in the spring.
Photo: Oregon SU

Cover cropping sounds like a panacea, but it gets complicated with the need for crop rotation and, of course, by the scale and variety of farming activity.  Vegetable farmers seeking to move to no-till, whether they are following conventional or organic methods, will probably find they  need to switch from row to fixed raised beds. Creating the beds is not hard; but because farming equipment  compacts the soil between the beds from repeated tracks, a grower may need  to plant different cover crops between the beds to impove the soil's ability to resist  compaction than the cover crop needed in  the raised beds. These additonal crops add  costs.

Among the factors farmers have to think about when selecting  cover crops  are:

• What's the goal? Is it  weed suppression, erosion control, nitrogen capture, adding organic matter, breaking hardpan, reducing the risk of soil diseases or pests, etc. [For some help in choosing a cover crop, Cornell offers this  Cover Crop Decision Tool.]

• Is the cover crop a good match for the character of the field's soil? - Alfalfa, e.g., needs fertile and warm temperatures to germinate as does forage raddish that promotes the break up of clay soils, but it will also attract harlequin beetels. Each field may have unique characteristics  requiring differenent cover crops. 

• What is the cash crop? Is it a field crop like many grains or legumes or is it  planted in rows? Can the cover crop be inter-planted with the cash crop, or does it need to follow the cash crop's harvest? 

• What tilling does the cover crop require? Can the cash crop sprout through last season's cover crop residue? Will the cover crop clog a seeder if its residue is left on top of the soil? 

• Will the cover crop's growth cycle be compatible with that of  the cash crop's? Will it be necessary to use a herbicide to clear the field for planting in order to harvest the cash crop in time for market or to prevent the cover crop from reseeding and becoming a weed. 

• How does crop rotation affect cover crop selection from year to year? 

Spiker aerator and tractor for reduced tillage.
A backyard gardener just needs a broad tooth fork.

Many, if not most, American farmers do    use  a mix of lite-tilling strategies, collectively called reduced tillage, usually in order to limit erosion and ideally  to minimize soil disturbance.  A small but increasing number of farmers are  also introducing  or expanding  no-till  practices into their tillage repertoire.

Farmers starting the move to no-till unfortunately frequently have to expect  yields  from these fields, especially for field crops like corn, to  decline until natural soil fertility is restored. This can be  a 7 - 9 year process   unless implementation is carefully managed -- that's a long time with a reduced income from a field until you start to see increased yields and lower costs!  Along with making such a  long term  commitment, no-till strategies need to  be tailored  for each  each field.

Cover cropping is an important component of no-till, but definitely a complicating factor.  [If you are interested in how cover crops can be employed  during  conversion to no-till to speed up the process, take a look at Ohio State University's Factsheet on Using Cover Crops to Convert to No-till.]

OSU  found that  growers can reduce the time to restore the soil's natural fertility, at least for some crops, to as little as only 2 - 3 years - a much more attractive proposition -- by employing a continuous living cover strategy, i.e.    using cover crops to eliminate/reduce the time that fields are devoid of plants. The benefits of  leaving plant material on top of the soil and roots  left undisturbed in ground over the winter months substantially promote restoration of soil health and reduce nutrient loss from erosion and runoff.  

Well, that's enough for now, I know that I have barely tilled the surface regarding  cover crops and no-till.

And remember

"There's no limit on how complicated things can get on account of one thing 

always leads to another." - E. B. White

Garden Preparation - February

Somedays it may be hard to think about gardening.

T'is February, a month high in suicides, but for gardeners, a time to think about the greener days coming.

For the ambitious backyard gardener, February can be the time to

• start such vegetables as celery, leeks, cabbages, cauliflower under lights;

• order seeds, if you haven't already succumbed to the urge; and

• spend a little time thinking about the sustainability of your garden.

If you are looking for more gardening advice about what to do in February, either search this blog using the term "February" for last year's post or click on the link labeled Root Concerns, the Rensselaer County Extension's newsletter,  located on this display's right side for its 2019 suggestions. Otherwise,  just continue reading here.

Simple Crop Rotation Plan

Rotation in my small garden I find is a challenge every year.  My plots are not divided evenly among the plants I decide to grow. Tomatoes always seem to take up about a 1/3 of my space; and, of course,  I like to include a few peppers and  eggplants.  Because these vegetables  are related to tomatoes, just rotating them in my small space does not necessarily do as much as it  might to minimize the risks of some pests or  diseases such as verticulum wilt (VW). Because VW can stay active in soil for 10 - 15 years, crop rotation in small gardens actually provides little protection against it.  That said, I do try to follow the scheme like the one listed below, but I also know that I have to compensate for my space constraints by putting more focus on soil building by rigorously adding  compost  and mulch  to maintain soil health, selecting varieties that are resistant to certain diseases (like VW) and experimenting with growing some plants, like eggplants, in containers filled with new  soil - I usually bury these pots in the ground to reduce the risks of their overheating and drying out. 

A simple crop rotation plan like the one listed below and followed over four years for common vegetables with plants from each group grown in a given garden space each year looks something like this:

                                Year 1:  Potatoes, tomatoes, eggplants, peppers

                                Year 2: Carrots and other root veggies, lettuces, spinach

                                Year 3: Cabbage family (Brussels sprouts, cauliflower etc.)

                                Year 4: Onions, garlic, leeks, legumes (beans, peas)

Sustainable Gardening, Sustainable Living - My Soapbox Topic for February

Cornell U. Botanical Garden - Sustainably beautiful.

Now, in line with the effort to think about  gardening during February, let's touch upon the concept of sustainable gardening.

The phrase simply identifies  a collection of practices with the goal that strives to produce better harvests both now and into the future by utilizing techniques  that are in harmony with local environments.  

Actually, I think all backyard gardeners   want to have sustainable gardens - they do not intentionally grow vegetables in ways that  exhausts the soil to the point that even weeds fail to thrive.  All gardeners realize that their next  growing season  requires planning and preparation during  the current  season.

Crop rotation, briefly mentioned above,  happens to be  one of the characteristics of sustainable  gardening.  The other main characteristics of sustainable gardening include:

• Minimizing negative environmental impacts: e.g. by avoiding or rarely using insecticides or pesticides;

• Working to  improve soil fertility: e.g. by adding compost and natural fertilizers to promote soil health and to  reduce reliance on commercial fertilizers. This not only saves money, but also may reduce carbon emissions by lowering the demand for those bags of 5-10-5;

• Promoting conservation and biological diversity:  e.g. by  mulching,  planting diverse crops that attract both pollinators and beneficial nemodotes and conserving water;

• Using community and local resources: e.g. by composting your own plant wastes and using neighborhood resources such as raked leaves or grass clippings (free of pesticides, of course) to recycle the nutrients locally; and most importantly...

• LEARNING & THINKING about  your gardening skills: e.g.  by finding out about best practices. Check the Internet  for your county's Cooperative Extension Service or (gasp)  look for a book at the public library about growing vegetables.

These goals also apply to gardeners using containers   In fact,   container gardeners actually are  employing many sustainable techniques automatically, e.g. they already  have little need for insecticides and they probably don't over water, but passing on their sustainable containers to  heirs is probably (still) uncommon. By choosing organic  soils and fertilizers to replenish container soils  and choosing disease resistant plant varieties container gardeners  also reduce demand for commercially produced products.  Their  small harvests from containers even count as using local resources; and importantly, their gardening activity conveys to friends and relations an awareness about sustainable efforts.  In this regard  both container and backyard gardeners should be mindful of their  roles, albeit seemingly small, in promoting sustainable methods and raising awareness about the need to recognize human society's dependence upon the natural environment.

For people without gardens, and that is most people in our society, if they are lucky enough to have access  to organic and/or locally grown vegetables, they can support those growers  by purchasing even a little of that produce.  If they do not easily have access to these sources as affordable options, then the most important thing they can do for themselves and for the planet is to simply buy a little bit less convenience or fast food - probably something that everyone should be doing.

In our society many small decisions about food choice by consumers eventually can have  impacts, so the choices of non-gardeners may be the most important in improving sustainable agricultural and eventually influencing better sustainable lifestyles.


And remember:

"Gardeners, I think, dream bigger dreams than emperors." - Mary Cantwell