Grassland Improvement for Gardeners

Spring 2019
Grassland – which can include many more species than grasses – is one way nature builds soils. English photo

By Will Bonsall

The only people who need to care about grasslands are those who keep livestock, right? Wrong! Anyone who cares about sustainable, self-reliant soil maintenance, whether on many acres or in a postage-stamp-sized backyard garden, should care a lot about grassland, because along with forests, that’s how Mother Nature builds and sustains soil tilth – not with animal manure, which represents a net loss to the system. Hint: It’s the grass that makes it all work, whether fed through a large grazing critter or used to build the soil more directly. If we seek long-term sustainability, then we must improve and maintain our grassland eco-efficiently by using as little imported material and energy as possible. Even those who keep livestock and have plenty of manure can still maximize their eco-efficiency by exploiting their hayfields more intensively and with more sustainable inputs.

My own veganic crop system contains neither domestic animals nor their “wastes,” yet I need lots of grass for mulch and to make compost. I distinguish between “grass” and “hay,” since my grass crop is usually used soon after mowing, without any curing or baling. In fact, “grass” is not even completely accurate, since my “grass” contains lots of clover, daisies, goldenrod, asters, ferns and every other sort of “weed” that fills out my grassland population. The more varied, the better, say I, since my earthworms and decay organisms are much less finicky than, say, dairy animals. Indeed, in my experience, the mixture gives me more total yield of biomass, both above ground and below, than grass alone. Why should I care about below-ground growth, which never gets mown? Because over time it dies and adds fertility to the grassland soil, thus nourishing more top growth; it’s another way sod is self-sustaining. Even if one has plenty of manure, home-grown or imported, using it to fertilize the hayfield that produced it is counterproductive in the larger scheme. It is more eco-efficient to use grass to make manure than vice versa (although it is still more eco-efficient to bypass the animal altogether).

Rather, we should feed the grass by using materials that are less valuable than the grass, in both the land and the energy used to produce them. That’s where forest residues – leaves and ramial chips – come in. I’ve described that in previous MOF&G articles, but I have still other techniques for improving grassland, some which do not involve adding material to the land so much as doing something to create fertility.

Experiments with Clover and Wood Ash

For example, when I started to improve my pasture, which was very run-out after a century and a half of dairy farming, I first overseeded clover, which was largely absent in the population. The clover sprouted here and there, but its growth was generally disappointing. Next, on a separate plot, I “limed” with wood ash, of which I had plenty. I’ve read that wood ash is about 16 percent lime calcium, the rest being potassium, magnesium, etc. – the whole spectrum of plant-derived minerals released by burning. Not only is ground limestone mere calcium carbonate, but it is the residue of marine algae deposited during the Cretaceous and other long-ago times. Mining, grinding and transporting it requires lots of energy – with a huge carbon footprint. It is neither balanced nor sustainable and, in my mind, is the antithesis of “organic.” The minerals in wood ash, on the other hand, come from nearby, albeit many feet deep where tree roots “mined” them. Derived from land plants, these minerals are roughly proportionate to what land plants require.

So I spread wood ash on my hayfield – the alkali itself benefited my naturally acidic soil – and what happened? The grass became a much darker green from the added nutrients, but the yield did not increase dramatically. After a while I realized that those added nutrients, while essential, were not the growth-limiting factor. For grass, nitrogen (N) is the key growth element. For clover and other legumes, calcium and potassium are more vital, as they create the conditions under which legume-associating bacteria can fix atmospheric nitrogen. The air is about 80 percent N, so we don’t need to import it or mine it, just sequester it from the wind. When I combined the two strategies, ash and clover seed, the results were dramatic: The ash encouraged the clover, which nourished the grass. Most important, everything came from the land itself. (Back then I even gathered some of my own clover seed.)

In Praise of Witchgrass

This may be a good place to put in a good word for witchgrass (aka quackgrass). I know witchgrass is one of the greatest nuisances in the garden, always trying to sneak in from the edges. In the hayfield, however, it is a powerful ally. Those same starchy runners that invade cultivated ground create a dense and productive sod that makes plenty of biomass in the tops (for compost, etc.) and even more below ground as those rhizomes senesce and decay, strengthening the sod itself from within. Of course it’s prudent to mow witchgrass before it ripens seed, although I pay little attention to that, counting on the heat of the compost heap to neutralize any seed. Other deep-rooted plants, such as salsify, chicory, dandelions and yellow dock, can have a similar beneficial effect, enriching sod beyond the effects of their own top yield. Witchgrass works much the same way.

I would have said that it’s a shame you can’t buy witchgrass seed in your garden supply center (go ahead, laugh, scream …), but in fact you don’t need to. Unless you’re in a new forest clearing, plenty of witchgrass runners are probably already scattered in your sod, just awaiting encouragement. Witchgrass responds marvelously to mulch, a major obstacle to no-till, but that also has implications for deliberately encouraging it outside the garden; more on that later.

Plowing and Reseeding

One way to improve grassland is to plow it under and reseed it occasionally, letting it be its own “green manure.” Back when I used a tractor, I also got a good effect by discing the sod in a spiral pattern, which chewed up the ground a bit but allowed most of the plants to rebound with renewed vigor. However, those methods are machine- and energy-intensive and (especially plowing) somewhat genocidal to the existing soil community, so I’ve largely lost interest in them.

Grass Responds to Irrigation

It’s important to appreciate the importance of water in flourishing grasslands, especially regarding the grass itself, and especially later in the season. The perennial monocot grasses tend to make great vegetative growth in spring; as the season waxes hotter and drier, they tend to shut down, and dicots (clovers and wildflowers) dominate the scene – lovely to look at but less productive of biomass than grasses. Adding abundant and frequent water later in the season helps the sod keep pumping out lush growth. This is true with most vegetative crops, but we tend to ignore it with grasslands. Maybe it’s not so easy to get water on the hayfield as on the lawn and garden, but the benefit is great in proportion to the effort.

Experimenting with Ramial Wood Chips

Another way to improve grassland with relatively little input is to exploit the “cover-the-ground” principle. This simply means that when you place any material (read “mulch”) on the surface of the earth, fertility increases out of proportion to the inherent fertility of the mulching material. Obviously manure or compost have that effect, but we want to use materials that have little or less value elsewhere, such as leaves or woody (ramial) chips. I experimented with spreading wood chips on some run-out hay land, and the results were disappointing: They soured the soil and made the sod even thinner. I repeated the experiment elsewhere, not spreading the chips evenly but plunking forkfuls here and there, about 2 feet in any direction. Under those little heaps the grass was not improved but was killed, but around the edges the grass grew lusher and greener, drawing strength from the dead and decaying sod under the heaps and sending roots into the cooler, moister environment there. Those lush rings expanded outward until they coalesced with neighboring rings. Meanwhile the heaps themselves became lusher as the rings grew inward, re-colonizing and pushing up through the decaying chips. Ultimately the whole plot was invigorated and for several years thereafter produced noticeably more grass than before, and without further treatment. The effect was not awe-inspiring but significant. A load of chicken manure would have had a much more dramatic and immediate effect, but at what cost? Manure is very concentrated, and its use must be compared with its possible use on other, more demanding crops, whereas forest residues – wood chips and tree leaves – are generally regarded as having very little fertility value, and indeed they are very low in nitrogen. Yet the increased grass yield was very high in N, most of which clearly did not come from the chips but from the air, sequestered by the soil community enhanced by those low-N materials. Parlaying something cheap and common into something precious – food – is at the heart of truly sustainable, truly organic gardening. We can spin gold thread out of straw.

Each of these techniques – enhanced seeding, ashes, watering, strip- or spot-mulching – has benefits out of proportion to the value of its inputs, but none of these methods is exclusive. In fact the results of any combination of them are synergistic, greater than the sum of its parts.

About the author: Will Bonsall lives in Industry, Maine, where he directs Scatterseed Project, a seed-saving enterprise. He is the author of “Will Bonsall’s Essential Guide to Radical Self-Reliant Gardening” (Chelsea Green, 2015). You can contact him at [email protected].

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