The Kitchen Gardener

Legumes to the Rescue!

Many of you reading these pages are probably doing so because you intend to either start a new garden this year, or expand an existing garden into something larger or more productive. Perhaps you have been so tempted by wonderful illustrations and colorful descriptions in seed catalogs, and inspired by what you've read here on TheKitchenGardener.com that you are chomping at the bit to start tearing up lawn and committing it to agrarian purpose; or perhaps you have been gardening for many years but never have enough space to plant everything you desire, and are eyeing that little patch of neighboring earth for more vegetable production. In either case, a word of caution - first year garden soils often do not produce abundantly. It's usually the case that recently turned soils lack not only the basic nutrients, but micronutrients, humic acids and organic enzymes, not to mention tilth, that often overlooked quality that pertains to the physical structure of soil.

To explain the deficiencies in new garden soil, we must dig a little bit into one of my favorite topics - soil biology. Contrary to the attitude of many mega-farms and purveyors of industrial agrochemicals, soil is much more than a media to hold nitrogen, phosphorus, and potassium. Good soil is an ecosystem - a complex web of hundreds of organisms operating in their own ecological niche but at the same time advancing the health of the system as a whole. It has been known for quite some time that plants need bacteria, fungi, protozoa, insects, worms, and various other critters to grow strong and healthy. These organisms are responsible for breaking down dead organic matter into nutrients that plants can use, converting inorganic materials (like rock) into biologically available compounds, and various other neat tricks that benefit the plants we grow in our gardens. What has come to light only in the past few years is the role plants themselves play in these ecosystems. It turns out that each plant produces significantly more carbohydrates than you would find if you ripped it out of the ground and ate it. Where do the additional carbohydrates go? In a fascinating example of symbiosis, the carbohydrates are exuded from plant roots, apparently for the purpose of nurturing the local colonies of critters mentioned above. These organisms (often referred to as the micro-herd) use the carbohydrates exuded by the plant as a source of food. Plant feeds micro-herd, micro-herd feeds plant. It's nature at its most elegant and also pragmatic.

So why do first-year gardens often underperform? Because the soil lacks the requisite microbiological activity to keep the plants healthy. The ecosystem of garden soil includes not only the microherd that feed the soil, but also the plants that feed the microherd. Simply put, this system isn't firing on all cylinders yet. Fortunately, there is something you can do to improve the situation, and hasten the day when your soil is teeming with life and your vegetables are bearing generously. Plant legumes!

One particularly important member of the micro-herd is the nitrogen-fixing bacteria. In point of fact, there are many strains of nitrogen fixing bacteria, most of which are found in the genus Rhizobium. These bacteria colonize the tissue of legumous plants, forming visible white nodules on the roots. Rhizobium are capable of a neat trick of chemistry that plants themselves can't perform - grabbing relatively inert nitrogen molecules from the air and fixing them as biomass, in a form plants can use. Nitrates, nitrites, and ammoniacal nitrogen wash quickly from soils when it rains or they simply escape again to the atmosphere, so having herd of bacteria drawing nitrogen back into the soil is tremendously valuable for your garden.

Legumes include members of the pea and bean family, as well as alfalfa, peanuts, and a few other distant cousins. The strategy is to heavily stack the deck with members of this family in the first year. Peas and beans in particular are not only good soil-builders, but they are productive, easy to grow, and generally not bothered by many pests. If you want to show success in your new garden, let me introduce you to a few of my favorite legumes:

Peas. Generally speaking, common peas are divided into three types - shell peas, snow peas, and snap peas. Shell peas are peas which are allowed to grow seeds inside the shell. Some might wonder why one would bother growing shell peas when a 1-pound bag of them can be bought for $0.99 in the frozen food aisle of the supermarket, but the taste of fresh shell peas from the garden is incomparable. They can be eaten straight from the pod, sweet as candy, or lightly sautéed in butter and garlic for an amazing side dish. On the opposite end of the pea spectrum are snow peas, a staple of wok cookery. Snow peas are picked before the pea seed matures, and are eaten for their edible pods. Somewhere between shell peas and snow peas are snap peas, a relative new kid on the garden block. Snap peas may be picked when young and eaten like snow peas, or when they have matured a bit and shelled. All peas like to grow in cool temperatures, and should therefore be started as soon as the ground can be worked in spring. They can also be planted in midsummer for fall harvest.

Fava beans. Favas should be planted like peas, in early spring. They require a bit more of a commitment than peas, remaining in the garden until midsummer before the seeds have finally matured inside the pods. Favas are good eating, whether shelled at the green-shelling stage (when the seeds are fully mature but still slightly soft and green), or when the seeds have completely matured and hardened. Favas not only produce edible seeds, but they fix large amounts of nitrogen, and what's more, the stalks are bulky and therefore make good fodder for the compost pile.

Other beans. There are more types of beans than you can shake a stick at. From dry shell beans to green beans, wax beans, French filet beans, bush and pole varieties, the universe of beans is vast. Perhaps because bean seeds are easy to harvest and save, bean seed preservation is a common practice among kitchen gardeners. Many heirloom varieties are available, and it's worth trying a few new varieties each year simply for the fun of it. For a good cross sampling of the many bean varieties available to you, check out the Vermont Bean Seed Company. Don't forget to try one of the most flavorful, loveable, but often overlooked of bush beans, the Roma style. Productive, buttery, and tender, they are not to be missed.

The basic message here is that by concentrating on legumes in your first-year garden, you will build good soil and enjoy an abundant harvest at the same time. Legumes are not especially fussy or difficult to care for, so success is virtually guaranteed, even for the novice. By the second year, the ecosystem in your new garden soil should be in full swing and you can switch to growing a broader selection of vegetables. But by this time you may have come to appreciate legumes so much that they will forever occupy a special place in your kitchen garden.

-Diggity