Organic Gardening

Almost every farmer is aware of organic techniques for fertilizing crops, yet the majority still use chemical fertilizers — why is that? Dig a little deeper (excusing the pun) and you will find that it is not uncommon for a family farm to have an organic garden for their own vegetables, but still use chemical fertilizers on their commercial crops. They know organic is better, so why use chemicals?

The answer lies in simple economics. Preparing compost is labor intensive, and labor is expensive. Also, specialized farmers rarely produce the right mix of high-carbon and high-nitrogen materials to produce compost in sufficient quantities to keep large acreage productive. Then there are the issues with pest control, which is easier with chemicals. That is one area I can’t claim biochar will help much — but for the soil fertilization it solves several problems at once.

The rising cost of petroleum-derived fertilizers has some traditional farmers taking a second look at organic methods already — add biochar to the mix and the equation turns around completely.

Adding biochar at the composting stage of organic field treatment adds little to the labor costs, just the effort required to produce the biochar itself. The effect, however, is substantial. Not only does biochar make the compost more effective — it makes those effects last much longer. Testing is still underway to determine how long the benefits last, and only time will tell (duh!) — but it appears that biochar enriched organic soil will remain productive for years, without the need for frequent application of additional compost. So those high labor costs can now be amortized over several (or many?) years. And small quantities of compost can be used each year to gradually reclaim a large area from the blight of chemical addiction.

So now the farmer has lower fertilizer costs and higher production. If the area requires irrigation, there may also be savings on water costs, because biochar enriched soil retains water better. Not to mention that the runoff is less polluted, and so our environment also benefits.

And each time the price of crude oil rises, these benefits only become more compelling.

I’ve seen several news reports that treat biochar as something that would be of benefit to third-world farmers who can not afford fertilizer. That kind of misconception needs to be wiped away with clear-headed analysis of the true costs and benefits — long term. And oh yes, it might help slow or even stop global warming, if adopted on a large scale.

If you are a serious gardener, and have plenty of money to burn, you can take a soil sample to a lab and get great information on what it contains, including trace minerals, and their quantities down to a hundredth of a percentage point. But really, in today’s economy, who can afford that? Besides, how much information do you really need?

If you are following good organic practices, your soil will have all the minerals and nutrients it needs to grow healthy plants and healthful vegetables. But sometimes you need to know what type of soil you are dealing with if you are just starting out, and have not added the rich composts and such. You basically, just want to know how acidic or alkaline the soil is, how the drainage is, and the relative proportions of clay, silt, gravel and sand.

Testing pH (acidity or alkalinity) is easy. The cheapest way is to buy pH test paper (it comes in little strips) and corresponding color chart. There are more expensive pH testing kits and even electronic devices available, if you want to use those just follow the instructions that come with them. For the simple paper strip test, dig a small sample of soil from a few inches below the surface, and remove any rocks, roots or organic materials. Put the sample in a clean glass container, and add distilled water until the mixture is like a think milkshake. Let it stand an hour. Put the paper pH strip in it, and wait one minute. Compare the color of the strip to the color chart to find the pH value.

Different plants like different pH levels, but most do well in a range of 6.5 to 7.2 — compost and organic matter tends to move the pH to more acidic levels (lower numbers), while lime is used to raise the number (more alkaline).

Next, check the soil permeability. Take a can with about 10 cm diameter, like a coffee can, and cut both ends off. Press it into the ground until just 5 cm is above ground. Fill that 5 cm space with water. Time how long it takes for 2 cm to drain out through the soil. That time depends in large part on how moist the soil is to start with, and sisnce you didn’t measure that, your first reading is of little value. But keep repeating the test over and over until the time remains about the same. That is the rate of absorbtion for water saturated soil. So long as that time is less than an hour, you have no problem. If over an hour, you have poor drainage, which means the soil is probably compacted, and does not get enough air below ground either. You need to add sand and orgainic material to improve the texture.

Finally, let’s see how much clay, silt, sand and gravel is in the soil. Take a clean glass jar with a lid, and fill it about 1/3 full with soil from just below the root-line for shallow rooted plants like grass. Fill the jar nearly completely with clean water, leaving just a little air to help make agiation more effective. Shake it good until everything is evenly mixed.

Take a magic marker type pen, and use it to mark sediment levels at different times. As soon as you stop shaking the jar, set it on a solid surface and mark the level of things that settle immediately. That is the sand and gravel. Wait 60 seconds, and mark again, where additional material has been deposited — that is the silt. Finally, you may have to wait anywhere from a couple hourse to a full day for the rest of the material to settle, leaving clear water above. That is the clay. Now, measuring the distance between each mark and dividing by the total height of the soil sample give you a percentage for each type of material.

Finding out what type of soil you are starting with is a good clue as to what you need to concentrate on adding to make the soil as fertile as possible. Luckily, good compost improves most soils, regardless of their original composition. Only highly acidic soils need anything more than rich compost, those need some sort of lime to reduce acidity. Lime is made from grinding up limestone, dolomite or chalk

Now that we have moved into our little bit of the tropics, ants are a huge challenge. They are everywhere. They come in all sizes, from tiny specks the size of the period at the end of this sentence, to big buggers with nasty looking pincers on their faces.

Some of the most problematic species here are the leaf-cutters. Fascinating creatures, they march out in long lines, forming two-directional high-ways that may go dozens of meters from their nest. They pass all kinds of tasty weeds and prolific plants to climb into your favorite and most unique specimen, which they immediately denude of leaves, each ant cutting out a piece about a quarter inch square, which they carry all the way back to their nest.

Back at the nest they carefully mulch the plundered leaves, to grow fungus. Not content with simple gardening though, they use that fungus to feed their livestock — little aphids that produce a sweet ‘honeydew’ the ants crave.

It is all very interesting and a miracle of nature, but when they target your favorite plant, it seems more diabolical than charming. They can strip all the leaves off a good sized bush overnight. Their first target here was our Tropical Almond tree. There they were very picky, only stripping the tender new-growth at the end of every branch.

Our Tropical Almond tree -- notice the chewed-up leaves, most visible near the top.

Some of these guys work in the morning and evening, and others work at night in the dark. Different unions I suppose. Either way, it is easiest to follow them with the help of a flashlight. The ones with pieces of leaves are heading toward the nest, just follow along the path of wavering leaf-bits, and watch where they disappear down a hole. That’s the nest.

To dissuade them from continuing their garden-marauding, just pour a gallon or so of boiling water down that hole. Yes, it’s wholesale slaughter of innocents, but sometimes you just have to draw the line. Leaf cutting ants in the woods and fields are fine by me — but not in my yard!

Well I imagine for a lot of our readers, you are anticipating the coming winter, and splitting the last of the firewood for the coming season. Our situation is a bit different. We just moved to a small cottage in a little village in Colima, Mexico. Just a couple miles from the coast, this is a tropical monsoon climate — lots of rain from June through October, then very little for the rest of the year.

We caught the end of the rainy season, moving here on October 2nd, and believe me when it rains it pours. Lots of lightning too, which I love. The heaviest rains come at night, so the lightning can be spectacular.

One of the first things we did was cut the weeds off our lot — with the help of hired machete wielders, who ignored my please to cut the weeds into pieces. Why? We just pile them here to burn… Well NO! we don’t burn weeds, we compost them. Make soil. ¡Oh Si! They understood completely. Then proceeded to cut the weeds at ground level, as they always did.

They know about composting, but don’t think it’s worth the trouble, when there are places nearby that have migajon — rich soil they dig for garden use. Now migajon is a bread paste/dough used for craft work and food (not exactly the same recipe I hope) — but how that applies to soil I haven’t yet figured out. In any case, it isn’t terra preta, and only retains its fertility for a year or two, then needs enrichment. Why not use compost? Too much work, they say. Add manure when needed.

Well compost is a lot of work, but I think when combined with biochar, it will be worthwhile, because the biochar will help ensure the nutrients in the compost are available for the plants, rather than leeched out after the first good rain.

So today I turned the small compost pile (it was about three cubic meters, but continues to shrink) which I am watering as needed and turning weekly. There is another pile with large uncut weeds, coconut shells, woody branches and such that will be mostly long-term compost, though for now one of the iguana’s is living there. (Our black iguana’s are another story…)

So I’m anticipating this small compost pile will be ready for use by the end of the year — we have temperatures in the 90s daily, and lows in the 70s, so the compost works pretty fast. And more exciting, I paid the herrero today to buy the materials he needs to make us a 55 gallon drum based charcoal/biochar kiln/retort. It should be ready Saturday, so I’m anticipating that too.

I’ll try to get some of my photos ready to illustrate a follow-up article for this, to show our works in progress. Meanwhile, I’d appreciate any comments or advice — have any of you tried organic gardening in a tropical or especially monsoon-tropical climate?

The organic gardener has several options for the biological control of pests. One of the earliest forms of organic pest management was to simply introduce predator species in the garden, the most common being ladybugs and praying mantis. Garden supply companies were quick to make available these natural predators, usually in the form of eggs, but in some cases selling live insects. You can thus introduce them en-mass, or you may choose to use the slower, and more natural method of simply encouraging the local populations of predatory species. Praying Mantis will eat beneficial insects as well as pests, so you may not want to have a large population invade your garden all at once, but encourage the few natural visitors.

Many people think of birds as garden-pests, but here too it really depends on the species. Some birds do not eat plants or fruit, but live on insects. Encouraging such species by providing bird houses near the garden will help prevent insect infestations. As we pointed out for the Praying Mantis, insectivore birds are indiscriminate eaters and will consume beneficial bugs as readily as pests, so it is best to maintain a delicate balance — nature tends to maintain it’s own balancing act, too many insect eaters in your garden will eat themselves out of house and home, and the will move on to better hunting grounds.

Bats are also great bug-eaters, though they rely mostly on night-flying insects. So if your garden is plagued by catepillars that grow into moths, you can reduce their numbers the following season by putting bat-houses in the trees near your garden. The bats will eat the moths, reducing the numbers available to lay the eggs that hatch into plant-eating catepillars.

You can also attack many pests on the micro-scale. Making compost-tea and spraying it on your plants can help prevent destructive bacteria and molds, as well as some insects. A properly made compost-tea (and we will discuss how to make that in a future post) will have beneficial bacteria, nemotodes and fungi, all of which work together to kill or displace the harmful sorts. Added to the soil, the tea will also help make minerals available to your plants, and helps aereate the soil so that plant roots get the oxygen they need.

Experience is the best teacher when it comes to biological control. Your specific needs are dictated by the types of plants your grow, and the types of pests and diseases that affect them. Be observant! If your plants have tiny aphids sucking the life out them, be sure you look close enough to notice them. If there are chunks eaten out of the leaves, try to find the culprit. Look at the undersides of the leaves, and observe the plant at different times of day. Watch the predators at work in your garden and see which species of predator prefers which prey, so you will know which ones you need when a pest species gets too numerous.