"Corn falls into the East Nishnabotna River in Montgomery County, Iowa. Severe row crop land erosion is occurring along the river." Caption/image credit, this and subsquent images:Gannon, Desmoines Register
The dramatic pictures you see in this post speak for themselves: Iowa crop land and even corn falling directly into a river. They symbolize mismanagement of the land by farmers, the Federal government, and corporations which lobby for the policies which lead to this problem. With conservation easement budgets recently cut way back by Congress, scenes like these will only get worse - much worse if the droughts experienced elsewhere in the world increase the export prices of US agricultural commodities. These scenes are linked directly to the Gulf dead zone. The pictured practices destroy fish and aquatic life - chemicals are sprayed directly into the stream - plug highway culverts with sediment, increase the risk of flood damage, and rapidly erode the productive capacity of the land. Consumer activism will never turn such bad land management practices into good. Only Federal farm policy can.
If you live in a corn producing state, I urge you to read the entire opinion piece in the Des Moines Register by Susan Heathcote, "Stop planting corn river bank to river bank," and then discuss it with your congressional representatives.
If your Congressman or Senator has been talking with farm lobby groups you will probably get back some talking point about 'most farmers being good stewards of the land,' which I address down the page, and the nation needing the export revenues to help the balance of trade. Show 'em photos like the one below and ask if good stewards farm like this?
Tell them you want conservation easements back, and that grassed water ways and tree-lined stream banks have to be maintained through good times and bad.
Soil loss from crop land as well as eventual sediment yield from a watershed both vary immensely, depending on location, land cover, and local practice. A few "bad actors" in a rural watershed can account for most of the problems experienced.
Most of the sediment that moves out of a small agricultural watershed in the corn belt states, for example, does so during and following spring snow melt - during April May & early June. It's called the 'big flush' effect if you live downstream.
'Stream-bank farming' can account for a disproportionate amount of the total agricultural pollution problem.
The steep stream banks you see in these photos are certain to collapse into next year's spring runoff; thus, millions of tons of soil and bank sediment are flushed into the Mississippi, moving toward the Gulf in pulses, year after year (A similar process operates in the Chesapeake and other critical river basins.)
This hits the taxpayer right in the wallet.
Have any idea of the size of the Federal budget needed to support the US Army Corps of Engineers dredging of the Mississippi river system navigation channel? It is huge. And it represents yet another proof that libertarian-style government, letting each entrepreneur do whatever they feel like in response to market conditions - can go against the larger interests of neighbors and of a nation.
Context is everything.
Let's say only 1 in 100 farmers plant fence row to fence row, and right up to the stream bank. Can't be such a big deal can it? Yes it can. If one farmer has a half mile of stream meandering through his thousand acres of crop land, and he plows under the 30-foot stream bank buffer on both sides, he gains roughly 158,000 ft2 of cropped area, which is about 3.6 acres. Iowa State University reports the 2005 yield average for Iowa was 173 bu/acre; so the stream-bank-planting farmer - our first bad guy in the sediment pollution food chain - gains 623 bushels of corn in this hypothetical example. That 623 bushels, at today's price of $4.25/bu (via cornquote.com), gets him $2,647 of additional income (before expenses and tax).
What's the public debit of his stream bank planting gain? I'm pretty sure it'll cost taxpayers at least that much to clean out a couple of downstream culverts every year, never mind the worth of fish and aquatic life, and so on, all the way down to New Orleans and out into the Gulf.
Iowa State University has estimated watershed sediment yield, from land surface erosion alone (excluding the pictured stream bank collapse and scouring), in one of the more vulnerable areas of the State to range from roughly 1 to 12 tons per acre per year, as presented in the following table. Sediment Yield means, by the way, the sediment which leaves the watershed - not just that which moves across an acre. Repeating: the specific numbers cited below refer only to that sediment which leaves the land surface planted in corn or soy and is carried overland, into the stream and on to it's point of discharge monitoring.
Because the corn crop in this hypothetical example is next to the water, let's go with the high end of 12 tpy sediment yield. The result - 3.6 acres added X 12 tpy/acre sediment yield = 43 tons of sediment yield per year resulting in a financial gain for the farmer of $2647/43 = $61 added revenue per ton of soil lost.
Based on a USEPA sponsored literature review, Channel Processes: Streambank Erosion
taking channel scouring and bank erosion into account will up the sediment yield or watershed "discharge" of sediment by at least 50%, perhaps by as much as 100%. Go look at the pictures at that link if you think I am exaggerating.
So yes, the bad guys do matter. The bad guys, in these examples, include Congressional lobbyists and foreign policy makers who have never canoed down a rural river in the heartland and have never seen what is really going on as a result of their trade policy ideas.