Essays

Wild On The Prairie: Plants

Cryptogamic Soil
August 6, 2000

The original Salvia greggii cutting bed at the Gone Native Arboretum is suffering. The plants are not flowering as well as they have in times past. Two 18 years old plants died. We added some of JoAnn Merritt's Passalong Asters and they wilt in half the time that they do in other beds. The soil does not retain moisture well.

We did not adequately mulch the bed the last 10 years. The 20 plants are near a few trees, but the tree leaves do not pile up and act as mulch. Last year I spread 2 40-pound bags of cow manure on the 20 foot long by 4-foot wide planting area. Not a sign of that soil amendment is present now. We might add a product that is part cow manure, composted cottonhulls, and alfalfa that caused mail-order medicinal herbs up-potted for observation to die from excess nitrogen.

Gardening is all about soil. Soil is full of critters, all working to tear apart decaying plant material. In arid soils not much leaf matter is produced. Plant matter produced in semi-desert habitats is desiccated by the blistering heat and then blown about to be ground into microscopic particles.

Our alkaline water slowly compacts the sandy soil. Without the actions that produce humus in moister climates the nutrients present in our native soils are used up after a few years of cultivation, unless we add organic material. (Or we can use the chemical fertilizers and pesticides to create and maintain the sterile growing medium preferred by modern agriculture.)

Take a walk through a vacant lot and look for cryptogams. When you notice these black crusts on the ground you might wonder if someone poured some roofing tar on the ground. In other places the soil looks as if it were contaminated by motor oil. If you look for these crusts you will find them, but most of the time folks walk right past them.

In a number of National Parks in the Southwest the Park Rangers have done a good job of "interpreting" cryptogams. At Natural Bridges, Chaco, Canyonlands, Painted Desert, and other parks visitors are told to stay on the trails to prevent killing them. "Do not murder cryptogams!"

If you are lucky, you might take a walk the day after a rain, when the black crusts have turned bright green. Cryptogams begin photosynthesis within five minutes of rainfall. Their biomass doubles within 24 hours. In moist evening light their color becomes fluorescent. At such times this most important habitat of arid soils becomes noticeable.

"Saaay whaaaat? Most important habitat? Burr has totally gotten full of bull now!" Every reader disgustedly shook their head from side to side when they read the above.

Have you ever noticed as you fly out of Midland you look down on the flat brown and see all the vehicle tracks crisscrossing? Some of those tracks have been there for years, and were caused by one pickup or jugtruck or workover rig bouncing across the pasture one time. And again, you say I am full of it -- am I right?

"It is a tough ol' desert, worthless and ugly. Who cares what happens to it? Let's race them 3-wheelers and dirt bikes and dune buggies and 4 wheel drive SUVs across the desert -- whooopeeee --- it's fun --- yahooooo!"

Only within the last 30 years have scientists begun discovering the complex connections that allow life to survive in arid habitats. "If it wasn't for the cryptogams, nothing would be growing."

"Yessirree, Burr is stretching this windy. Ain't nobody gonna believe that!"

Well, folks, that is what makes studying the natural world so much fun. "The Good Lord is a sight smarter than us!" says a folksy preacher on the TV. The more a person learns about how wonderfully intricate and complex this world is, the more that a fascination grows within. How utterly joyful it is to learn of cryptogams!

Cryptogams are communities of algae, fungus, and bacteria. When wet, communities of protozoa live within. Nitrogen is usually manufactured by plant decay, but not in arid soils. Only very miniscule amounts are produced. One of the most important members of the habitat is Nostoc commune var. flagelliforme. It is a species of blue-green algae. Nostoc takes nitrogen out of the air and through symbiotic fungal hyphae laced around the algae the nitrogen is passed on to the soil. The nitrifying bacteria Azotobacter, Nitrosococus, and Nitrosomonas are present in the black crust as well. The hyphae of Actinomycetes and Streptomycetes bring soil moisture up to the cryptogamic crust.

The Nostoc breaks down alumino-silicates in the soil with its secretions. The extractable silica increase and form into colloids, which helps caliche to form. Yes, Nostoc causes a soft rock to form, as well as making plants grow. Amazingly important stuff, isn't it? Those funny little warts of crusty black gunk are wonderful!

When we wish to make a new trail at Sibley, we lead kids across a grassy or weedy patch until 300 individual feet have trod along the same line. By then the soil is bare, and it remains bare for years without any maintenance. "Nostoc is dead. Long live Nostoc, Nostoc the king."

The southern Llano Estacado is almost flat. When a good downpour occurs, water pools up and then slowly slides along to lower places. Cryptogams have another function -- to serve as tiny minature dams. After a rain, you may notice where tiny bits of flotsam have piled up after the puddles have been absorbed into the soil. Look around for some cryptogamic crusts nearby.

Phosphorus is processed, then supplied to the cryptogams from that leaf litter and little pieces of scat (animal excrement) by the various fungi that are part of the cryptogams. The fungi attach their hyphae to the flotsam and process it until totally decomposed.

The mystifying and unknown world beneath our feet remains unnoticed by even naturalists until a startling occurrence unleashes a chain reaction of curiousity. Naturalist Brandon Young examined the underneath side of hay bales in the Junior Master Gardener compound at the Sibley Nature Center. The June 29th rain brought 5 Blackheaded Snakes to the soil surface under the bales. He caught them and placed them in an aquarium with some sand, and within a few hours all had knotted up together. Was it mating behavior? Some snakes are known for mating swarms, but we found no previous mention of the behavior for Blackheaded Snakes in any of The Sibley Library's books.

In previous columns we have talked about the billions of termites that emerge after a rain, and the millions of rainbugs (velvet mites) that emerge to eat the termites. At the same time geophilid centipedes are easily found. What are the roles of the geophilid centipedes? Books claim they eat earthworms, but in West Texas earthworms never common except in organic gardens. These harmless little centipedes are often spotted zippering along. Little snakes such as the Blackheaded sometimes eat the geophilids. How many geophilid centipedes, earthworms and Blackheaded snakes are found per acre? No one knows. Science knows there is a connection between them, but that is about all.

We could fill a complete newspaper page with questions about things that live in the soil. I guess agri-biz's answer of "Kill them all and let God sort 'em out" is the only way we simple humans can deal with the complexity of the natural world. Or is it?