Starting your garden for the season begins with prepping the soil. Even if you are turning over the first spade-full of loam, it’s important to pay attention to what nutrients your soil requires. Gardening year after year in the same plot depletes the earth of nitrogen and other beneficial ingredients. It’s tempting to solve for this by dumping large volumes of fertilizer into the ground and wandering off for the day. The local waterways would appreciate it if you’d be more scientific and less generous with your fertilizing.
If fresh eggs isn’t a good enough reason to keep chickens, another great reason is their guano makes for an incredible source of natural fertilizer.
On Cape Cod, comfortably ensconced in the modern trappings of the 21st century, it’s fair to assume few of us lose much sleep over our crops’ yields, let alone how we will feed our livestock during the winter. We, the weekend gardener, would do well to listen to the lessons of the agrarian past if we expect our small plots to produce year after year without destroying the nature around it.
Fertilizers are nothing new. Humans have been using them for as long as we’ve farmed. The why they work is a recent, relatively speaking, discovery. Humans tried all manner of fertilizers, some of which still are very much in use, though in a different form.
In addition to throwing stuff on our fields that appeared to help plants, farmers left fields alone for one season to let soil depleted of essential nutrients rebound. This meant that a large portion—in pre-industrial England up to one-third—of arable land was left unproductive in any given year. This was bad for businesses in most years and devastating when crops failed altogether.
Farmers soon found that planting turnips and other cover crops helped the land regain its footing for the following season, not to mention providing food for livestock during the winter.
Making your own natural compost is an easy, cost-effective way to fortify your garden soil each year.
A short-lived breakthrough in fertilizers occurred in the 19th century when the world came to realize the amazing properties of guano. This isn’t to say no one had ever used guano; its use as a fertilizer can be traced much further back, but rather the sudden and widespread consumption of the stuff. Bird droppings, high in nitrates, increased crop yields in some places up to three-fold. The islands off the coast of Peru, in particular, became hot spots of mining. Ships brimming with the stale leftovers of seabird meals found their way into Woods Hole where their cargo was unloaded, mixed with bits of local fish and sold to farmers. The Pacific Guano Works, located on Penzance Point, churned out its product for the brief time before the islands of bird poop were all but exhausted. The birds had worked for centuries to accumulate great island mountains of guano, and humans took it all away in no time at all.
Modern chemical fertilizers can trace their ancestry to a process developed in Germany by the scientist Fritz Haber, who developed the method to process nitrogen by gathering out of the air. This discovery came just in time for the German war effort in 1914, as the Allied powers controlled most of the organic sources of nitrogen, a key ingredient in explosives. Though Haber’s initial intentions were agricultural, his legacy would plunge into controversy for his role in the development of poison gas first employed by Germany on the eastern front.
Nitrate’s role in explosives meant that its production took off during the second World War. Ordnance of all kinds were in high demand; US planes alone would drop nearly a million and a half tons of bombs on Europe. The need for large amounts of explosives evaporated after the end of hostilities, but the capacity for nitrate production remained. This oversupply soon met with a new demand. What happened next became known as the green revolution.
Mixing manure into your garden soil is a great way to add nutrients into your soil.
New hybridized strands of staple crops came on the scene. Their high yields depended on chemical fertilizers high in nitrogen, and the United States, virtually alone in a bomb-shattered world, could produce large quantities of it. These innovations undeniably did great good in a world whose population was soaring, but that legacy is marred by the extreme levels of environmental destruction wrought by the wide use of nitrogen-heavy fertilizers. Perhaps most striking, the single-largest crop Americans sow and care for each year by surface area is our lawn. The waves of green so meticulously pored over require large amounts of human attention through the application of pesticides and chemical fertilizers.
Now we come back to the Cape Cod garden. Nitrogen has for many years been a serious issue on the Cape. We needn’t spill more ink on that topic. Working in our garden we can look way back to older farming methods, viewed of course through the modern lens to grow our vegetables. Organic fertilizers are a good start; dehydrated manures and compost are readily available. Covering beds with seaweed in the fall is another wonderful, and free, option here on the Cape.
For a nominal fee you can send soil samples to the University of Massachusetts Center for Agriculture, Food and the Environment, where they can be tested for nutrient levels and PH and let you know if there are elevated levels of heavy metals such as lead. This process too will allow help you keep your garden green without harm to our local waterways by letting you know just what and how much your soil needs.
Crop rotation still holds its place in the gardeners’ annual plans. Heavily feeding plants like tomatoes and corn benefit from placement in soil where the previous year’s legumes grew. Bacteria in properly inoculated beans and peas work to fix nitrogen from the air into the soil. As the season comes to an end in the fall, a cover crop of winter rye also helps give your garden a springtime boost. Even if you managed to balance your yearly soil nutrients, it’s a good idea to move your plants around from year to year to avoid disease, such as club root in broccoli and cabbage.
When the soil is finally workable and you’re ready to turn over your garden for the 2023 planting season, keep in mind that you also play a part in the health of the natural Cape as well.