The Hampton Gardener: Manure and other ways to add nutrients to garden soil

It’s been a very long winter, but take heart. On Friday, spring will have sprung and all will be well in the garden. Almost.

At one point in January there was a great meteorological debate as an “official” thermometer in Westhampton measured 13 degrees below zero two nights in a row. And as if that wasn’t strange enough, just a dozen miles away, it was 15 degrees warmer. The final verdict from the National Weather Service, though, was that the readings were accurate and probably the coldest out here in at least a decade.

Thankfully we’re past that incredibly cold snap, though it will be many weeks before we can tally the final damage to those borderline hardy plants that will show the ravages of winter as the season progresses. For now, we need to get back to our vegetable garden projects as the clock is ticking and Mother Nature doesn’t sit around and wait until we decide that we’re ready.

As the threat of frozen soil dwindles, we’ve got one more chance to work with the garden soil and do the few things that we can in the spring to enrich it and add as much organic content as possible. There are several reasons for this and the most obvious is basic—our native soils on the East End are sandy.

Sandy soil has been great for potato farmers and grape growers where heavier soils could be disastrous. If you live anywhere outside the old established villages where gardens have been tended for hundreds of years and where large deciduous trees have dropped their leaves and twigs to build the soil below, you’ve got sand. And as you move farther from the villages and closer to the shorelines, the organic layer or top soil becomes thinner and thinner and the sand deeper and deeper.

But for the home vegetable garden, the ideal soil is one rich in organic material. Not only that, but the best soil is high in organic nutrients, high in the organics that retain moisture, and contains a rich biotic layer that encourages soil microorganisms that allow the plant roots to absorb nutrients.

Now, you can garden in sand without adding any organic matter, but you won’t be doing anything more than modified hydroponics by adding a nearly constant stream of nutrients and water. This is inexcusable and nothing short of pollution as only a small amount of the nutrients—fertilizer, usually in a chemical form—becomes available to the garden plants. The balance will wash right down to the water table where it eventually ends up in our drinking water, bays, ponds and even the ocean.

When we add organic matter to the sandy soil and we use fertilizers judiciously, they become bound to the soil particles and remain there for use by the plants. This is best for your garden and for the cherished environment.

Knowing the best type of organic nutrients to add, and what not to add, will be an important first step to a successful garden. This week we will discuss animal manures, compost, mulch, peat moss and topsoil.

Animal manures (cow dung is best and horse waste is second best) can be a great way to add organics to garden soils, but keep in mind that these manures can’t be used right from the barn. Fresh manure is referred to as “hot” and it needs to be composted from several months to a year before it gets used in the garden.

The composting process kills the harmful bacteria in manure and encourages the breakdown of feces to a friable material that is dry and easily worked into the soil. You’ll have trouble finding cow manure out here, but there’s plenty of horse manure.

The best horse manure will come from a small stable with only a few horses where the manure isn’t treated with disinfectants. Better yet is manure that has been separated from the wood shavings that are urine soaked. Smaller operations with only a few horses muck their stalls and do this separation on the spot. Larger operations just put everything into dumpsters where it’s then carted off for commercial composting.

You can also buy bagged manure that is pre-composted at garden centers. This can be applied to the top of the garden soil, then tilled in. Now is the perfect time of the year to do this.

Keep in mind that bagged manure is great for smaller gardens, but isn’t practical for larger plots.

The next thing you should be adding to your garden soil is compost. Lots and lots of compost.

If you composted last year, your pile should be well rotted by now and chock full of worms and microbes that will bring your sandy soil to life. Keep it moist in the hottest and driest of summer days and it will also dramatically reduce your need for fertilizers.

Compost should be added at the rate of 2 to 3 inches every year and it should be worked into the soil to a depth of 6 to 8 inches or more. This can be done by hand (actually a shovel or fork is more efficient) but it’s much more economical and easier on the back to use a mini tiller.

A Mantis rototiller works well in gardens in the hundreds of square feet, but once you start to get over 1,000 square feet, a larger tiller such as a Troy Built (for larger machines rear tine tillers are best) or a commercial tiller is better.

Many tool rental stores rent tillers and you can usually get the whole job done in just a few hours.

While soil-building can and is often done in the spring, it’s actually best done in the early fall, as the freezing and thawing of the soil in the winter months further breaks down and mixes both manures and composts.

Mulches can also add to the organic content of your garden soil and you may have noticed this if you apply aged hardwood chips, coco hulls, buckwheat hulls and similar materials to reduce weeds and retain soil moisture. Every year you need to add more as last year’s mulch is broken down and composted by soil microbes that come into contact with and digest it.

Contrary to years of misguided use, peat moss is not a good soil-builder and its use is considered environmentally controversial as we begin to better understand that the “renewable” peat bogs of Canada may not be quite so renewable. Peat also adds little in the way of nutrients. Compost is much more desirable.

For new gardens that need an instant start, some will import large amounts of topsoil. I can’t tell you how many horror stories I’ve heard about topsoil that has resulted in disasters.

If this is the way you choose to start, be very, very careful who you buy it from and know in advance where it’s coming from. If you’re told the topsoil is farm soil, it’s probably a rip-off.

Non-native soils can bring in weeds that can overtake the gardens of the best intentions as much of the topsoil that we buy these days is actually manufactured through composting. This can be fine, but try to find out as much about the soil as possible before it gets dumped in your yard.

Again and again and again, there is nothing as good as the compost you can make on your own and add to your garden every year. Second best would be manures from small horse farms.

Keep growing.

Andrew Messinger has been a professional horticulturist for more than 30 years. He divides his time between homes and gardens in Southampton, Westchester and the Catskills. E-mail him at: Andrew@hamptongardener.com. The Hampton Gardener is a registered trademark.