Ranch Soil: The Factory Outside the Cow

One Square Foot

Not the pat. The splash next to it.

A cow urinates eight to twelve times a day, about sixty fluid ounces at a time, and she does not spread it around. Each splash lands on roughly one square foot — a floor tile — and on that tile it puts down the equivalent of 400 pounds of nitrogen and 800 pounds of potash per acre. No farmer would spread fertiliser that heavy across a whole field. The cow does it a dozen times a day, one tile at a time. The pat beside it carries the phosphorus.

That is where the minerals in the grass go. Not into the cow. Through her.

She is not a consumer of the pasture. She is a pump. Grass goes in one end, and nearly all of its minerals come out the other, in a form the soil can use.

It is not a perfect pump. Urine is mostly urea, and urea on warm ground turns to ammonia and drifts off. A quarter or more of that nitrogen can go up into the air before a root ever finds it. The factory outside the cow has a gas leak, the same as the one inside her.

And what catches the rest is a second herd.

A teaspoon of rumen fluid held 150 billion microbes. A teaspoon of ordinary farm soil holds somewhere between 100 million and a billion bacteria, several yards of fungal thread and a few thousand protozoa. Thinner than the vat, but the vat was forty gallons and the field goes on for miles. Add it up and the living things in the top six inches of one acre of decent pasture weigh about a ton and a half — the weight of two dairy cows.

There are as many pounds of livestock under this pasture as on it. They are just too small to see.

One Square Yard

Pull back to the pat.

Within hours of it landing, something has arrived. Dung beetles find a fresh pat by smell, and they come in three trades. Tunnelers dig straight down beneath it and haul the dung into chambers under the ground. Rollers carve a ball, roll it away and bury it somewhere else. Dwellers simply move in and raise their young inside.

Where all three are working, a six-pound pat can be underground within 36 to 48 hours. The nitrogen goes with it, into the root zone, before the air can take it. The flies that would have bred in it lose their nursery. The parasite eggs the cow passed lose their ride to the next mouthful of grass.

Where there are no beetles, the pat sits. It can take six months to two years to break down. It smothers the grass beneath it, and cattle will not graze the ring around it, so the best-fed grass on the pasture goes uneaten.

Nobody hires the cleanup crew. They come with the grass, if they are allowed to.

One Acre

Pull back again, to 4,840 square yards.

Here is the problem with using a cow as a fertiliser spreader: she is terrible at it.

Left to herself on a big pasture she drops her manure where she spends her time — around the water tank, under the shade trees, along the fences. One Mississippi study put it plainly: the nutrients land on about 20 percent of the pasture. Missouri researchers found that when cattle had to walk 1,100 feet to water, phosphorus and potassium piled up in the soil near the tank; when water was less than 500 feet from any point in the field, the soil tests came back even. Fifteen to twenty percent of the manure in a badly laid-out pasture is dropped in the lane on the way to drink.

Then there is the arithmetic of time.

The cows do not make more manure when they are moved. A cow drops four to six thousand pats a year either way. What changes is where they land. Crowd the herd onto a small piece of ground for a day or two and they cannot all stand by the water tank; the manure goes where the cattle are, and the cattle are everywhere.

The fix for a bad spreader is not a machine. It is a wire and a decision: move them.

But the reason to move them is only half about manure. The other half is what the manure is feeding.

Ten Feet Down

The grass a cow eats is the smaller part of the plant.

Big bluestem, the tall grass of the old prairie, sends its main roots ten feet into the ground — the height of a basketball hoop, straight down. Even on dry short-grass range, blue grama roots average more than three feet deep. When the pat and the beetles push nitrogen into the soil, this is what drinks it.

And the roots are why a pasture can be eaten and go on living, which a tree cannot. A tree grows from the tips of its twigs, out where a mouth can reach them. A grass plant grows from the bottom. Its growing point — the little engine that makes new leaves — sits at or near the surface of the soil, below the reach of a cow’s tongue. She takes the top of the plant. The engine is untouched, and it starts again.

The government’s own range handbook says it in six words: the leaves are the food factory. The roots are the warehouse, and the warehouse has a rule.

The plant makes twice the leaf it needs. It can spare the first half. Past that, it starts eating its own warehouse, and the roots that hold the soil, find the water and store the winter’s reserves quietly stop.

A cow can starve the roots without ever touching them.

There is a sweet spot. A grass plant cut down to an inch grows slowly, because it has almost no leaf to catch light. A plant left to grow tall and stemmy is shading its own lower leaves and turning to lignin. In between, in the first several inches of regrowth, it grows fastest and best. For a tall fescue pasture the rule of thumb is to turn cattle in at six to eight inches and take them out at three or four. Which brings you to the ingredient nobody can see.

Thirty Days

Rest.

A pasture grazed and then left alone is growing. A pasture grazed every day is not, because every new leaf is eaten as it appears. The whole art of grazing management is deciding how many days of the year a piece of ground is being eaten and how many it is left to grow.

The old way is to open one gate in spring and close it in fall. Cattle on a single big pasture all season eat what they like where they like, and by the numbers they use only 30 to 50 percent of the grass that grew. The rest is trampled, fouled, or grows old and tough beside the water tank.

The other way is to cut the pasture into pieces and move the herd through them. The same 100 steers on 40 acres are 2.5 head per acre for the season. Put them in a five-acre paddock and, for the two or three days they are in it, they are 20 head per acre — eight times as crowded, and moved before they can do harm. Then that paddock gets its rest.

The rancher who does this is not really managing cattle. He is managing days.

And the grass is not one thing. The cool-season grasses — fescue, orchardgrass, brome, wheatgrass — do their growing between about 60 and 80 degrees. Above that they slow down or stop, and pasture across the country falls into what graziers call the summer slump. The warm-season grasses — bluestem, switchgrass, bermudagrass — wake up exactly then. A rancher who plants both is planting a calendar: one crop for May and September, another for July.

There is even a way to graze in January. Stop grazing a fescue field in mid-August, give it a little nitrogen, and let it stand. Every inch it grows is worth 300 to 400 pounds of forage an acre. By winter it can feed a 1,200-pound cow for sixty days or more, standing in the field, on grass that cured where it grew. Missouri’s extension service prices a day of that at about 50 cents a cow. A day of hay is $1.56.

By the dead of winter, dormant grass may be down to seven or eight percent protein, or on the driest range as low as four. Which is where the first story began, with a cow standing in a field of paper-brown grass, living on it anyway.

One Year

Pull back to the whole ranch, and run the clock.

On a mountain-valley ranch in the West the year goes like this. In April and May the ditch opens, the meadows green up, and the cows and their new calves get a rotation or two on the irrigated ground. In June, as the snow retreats up the mountain, the cattle go up behind it — onto the summer permit, often on the national forest, where the season on one set of Montana allotments runs from July 1 to October 15. In late July or August the meadows they left are cut for hay. The regrowth is left standing. In the fall the cattle come down, the calves are weaned, and from November to March the herd eats the stockpile and then the hay, at something like 1.2 tons of hay per cow across the winter.

Even the calves are timed to the grass. A cow’s appetite peaks about two months after she calves, so ranchers try to land that peak on the green. In a South Dakota trial that compared February, April and June calving, the February calves died at three times the rate of the later ones — six percent against two — and the operation that calved with the grass made more money, not less.

The land all this runs on is the land nothing else can use.

Take the cattle off that ground and it grows exactly what it grows now, for nobody. The factory outside the cow is the only one that can be built there.

But it needs water. And in the West the water is the whole story.

One Acre-Foot

Pull back to the valley floor, and look at the meadow.

A grass-hay meadow near Greeley, Colorado, uses about 27 inches of water in a growing season. Alfalfa uses more than 30. In a country where the rain does not come close to that, the difference is carried to the field in a ditch, and the ditch is measured in a unit most people have never pictured.

Who gets the water is decided by a date. Under the law of the West, the first person to take water from a stream and put it to use has the first right, forever: first in time, first in right. When the creek runs low, the oldest right takes its full share before the next one takes any. A senior user who is short makes a call, and the water commissioner walks the ditches and closes headgates until the senior is satisfied. A right that goes unused for long enough can be lost. In Colorado, ten years of not using it is enough.

Most of the meadows on the western side of the country are still watered the oldest way there is. Two-thirds of the irrigated pasture in America is gravity-fed: a ditch on the high side of the field, a board pulled out, and water sheeting across the grass. Engineers call this wild flooding and rate it at 15 to 40 percent efficient, against about 85 for a modern center pivot. It looks like waste. Here is the twist.

The water that soaks past the roots does not disappear. It goes into the ground, moves slowly downhill through the gravel of the valley floor, and comes back out into the river weeks and months later — in August and September, when the snowmelt is long gone and the river would otherwise be at its lowest. A 1989 study of the New Fork irrigation district in Wyoming found that of the water diverted onto the meadows in June and July, about 70 percent returned to the river later in the season. On Montana’s Smith River, those return flows are 60 to 70 percent of the late-summer flow. When Idaho’s Snake River Plain converted from flood to sprinklers over the last century, the accidental recharge of its aquifer fell from about 3.7 million acre-feet a year to about 160,000.

The leaky meadow is the valley’s second reservoir. It takes the flood in June and gives it back in September.

It also does something a reservoir cannot. Flood-irrigated grass hay covers only 2.5 percent of the irrigated land in the Intermountain West, and it provides 58 percent of the region’s temporary wetland habitat — the shallow water the ducks and cranes use in spring. The meadow floods on purpose the way the river once flooded by accident.

So the ranch is not just where the grass grows. It is where the water waits. And all of it — the ditch, the meadow, the hay, the calf on the green — is downstream of one thing.

One Hundred Miles Up

Pull back until the ranch is a dot, and look at the mountains.

In the American West, somewhere between half and four-fifths of the water people use starts as snow. The Geological Survey puts it at as much as 75 percent in some states; the Natural Resources Conservation Service, which measures it, says 50 to 80. The snowpack is a reservoir that fills all winter for free and releases itself in spring, and there is no dam, canal or pump in the region that is not downstream of it.

Which is why, since 1935, the federal government has been weighing it.

High in the mountains, at more than 750 automated stations and 900 manual snow courses, sits a device called a snow pillow — a flat bladder of steel or rubber, filled with fluid, that the snow falls onto and that weighs it. Snow depth is meaningless; what matters is how much water is in it, the snow water equivalent, and the pillows report it every day to a computer that turns it into a forecast. The forecasts come out monthly from January to June. April 1 is the day that counts, because that is when the pack usually peaks. Irrigation districts set their allocations by it. Ranchers decide how many cows to keep by it.

A ranch’s year is decided in February, at 10,000 feet, by a pillow under the snow.

Here is what the pillows said this year.

Now walk it back down the mountain. Less snow is less water in the ditch. Less water in the ditch is a thinner cut of hay in July and a meadow that gives less back to the river in September. Less rain on the range is grass that stops growing in June and stands at four percent protein by fall. The pat still lands, the beetles still come, the roots are still ten feet down — but the factory is running short of its first input, and it shows in the only ledger the government keeps on grass.

Over the long run the snowpack has been thinning: the April 1 pack across the West is down somewhere around 15 to 30 percent since the 1950s, a loss researchers compare to the volume of Lake Mead. But no trend explains this year. This year the reservoir on the mountain simply did not fill, and everything below it — the meadow, the hay barn, the cow, the calf — is living on what it got.

The Ledger

Here is the whole story in one line.

The cow is half of a machine. The other half is the ground she stands on, and the ground runs on snow.

She hands back more than seventy percent of everything she eats. Beetles bury it in two days. Roots ten feet deep drink it. The grass grows from the bottom so that she can eat the top, and it grows back in thirty days if it is left alone — and it is left alone only if somebody moves the cattle. Under the pasture a second herd, the weight of two cows an acre, does the work of turning last year’s manure into this year’s grass. The meadow drinks two acre-feet a summer, leaks most of it back to the river, and the river is a mountain melting.

None of it is waste. The pat is a delivery. The flood is a savings account. The rest days are an ingredient. The snow is the whole budget.

This year the budget came in at the lowest level anyone has measured, and half the country’s grass is showing it. The cattle will eat what the mountain allowed. That has always been the deal.

Next year’s grass starts in a few weeks, when the first snow settles onto a pillow at 10,000 feet. Then the factory outside the cow will do what it has always done. It will wait until April to find out what it has to work with.