I have no doubt that ASAP readers appreciate the benefits of crop rotation to soil and water.  So why is our landscape dominated by the corn monoculture and or corn-soybean bi-culture?  Many will argue that money and time are the main reasons for this but do the numbers support this.  Looking at the NASS data base for Illinois and Iowa, I see per bushel prices for both corn and soybean have doubled since 2001.  The total value of the corn crop has actually tripled because yield-per-acre also rose by about 15% during this time period. The total value of the soybean crop has not climbed as much because productivity has changed little and acreage has been lost to corn.  The total number of acres (about 0.5 billion) devoted to these two crops has actually not changed much.

            Even though annual corn and soybean rotations could be diversified without losing an annual cash crop by adding cover crops, few farmers include winter annuals in their rotations.  Singer and Nusser (2007) surveyed farmers in the corn belt and found only 18% of them had ever used cover crops and that in 2005, those who did planted them on just 6% of their farmland.  Fear of yield loss and the extra time constraints were cited as reasons not to use covers.  Research is doing much to reduce and clarify the risks associated with cover crop management in corn and soybean systems (eg: Miguez and Bollero, 2005; .  This, and improvements in planters are making cover cropping a real option for mainstream agriculture.  Over half the farmers Singer and Nusser surveyed indicated they would cover crop if cost-sharing was available. They identified a mean minimum payment price needed to promote adoption of $56.81/ha or $23/ac.  If one multiplies that value by the acres planted to corn and soybean in Illinois and Iowa last year, they’d find it would have cost us a billion dollars to protect the soil.  Hind sight is probably going to tell me and other tax payers this is worth the cost.  

            The cost of flood damage in Iowa had topped $1.5 billion last month when the White House asked Congress for nearly 2 billion dollars in emergency disaster aid to address the historic floods.  This was well before water levels peaked.  A financial argument for cover cropping can be strengthened if we accept National Weather Service findings that flood damage estimates typically underestimate costs by an average of 40% (Pielke et al. 2002).  Planting cover crops would not have stopped the rains but countless studies indicate their presence would have reduced flooding, leaching and erosion and with this, done much to keep needed nutrients and organic matter where they belonged (eg: Jiang et al. 2008; Kladivko et al. 2004; Gowda et al. 2008).  The influence that current agriculture practices had on flooding made national news (Achenbach, 2008).  Changes in drainage and hydrology were cited in addition to cropping patterns.  By removing perennials or actively growing plants from the landscape we have reduced evapotranspiration and increased spring runoff to streams (Zhang and Schilling, 2006).  The argument that crop diversification is needed to help cope with climate change has been met with counter arguments offering up continuous GM corn grown with no-tillage practices as a superior alternative.  The data on organic matter has yet to come in; certainly no one disputes that reduced tillage can reduce erosion. In that scenario, bare or plant-free soil would remain a spring problem. 

            It is good we had at least some perennials in place this spring thanks to the CRP program.  Growing plants helps cope with water onslaughts by removing and slowing water movement.   CRP lands can also supply emergency feed to livestock.  Release of CRP lands for feed has been approved in the 48 flood damaged counties in Illinois but, rather than pay them more for this emergency relief, the Farm Service Agency will reducing payments by 25% for acreage opened for grazing.  Apparently appreciation for the conservation value of perennials has not gone up as a result of recent floods. As usual, our minds are on our stomachs.  Rising food and energy prices have caused many to look for solutions.  Large scale agriculture seems to be considering more monoculture corn while small scale producers are diversifying markets and crops.

            If we can resist over simplifying the challenge of land management to one that pits diverse, tillage and management-intensive farming against simple, input and technology- intensive farming we are likely to make more progress.  As currently practiced, common organic and conventional rotations have different strengths and weaknesses.  It is difficult to compare the two approaches because organic systems use crop rotation and cultural practices to do much more than protect the soil.  Cropping pattern and cultural techniques must also supply and retain nutrients, control weeds, disease, and reduce insect pressure in organic systems.  Imagine the subsidy organic farming systems will provide to mainstream agriculture if we figure this out.  In my experience, maintaining adequate weed control in medium to fine textured soils is a bigger challenge for organic growers than building soil quality. 

            We’re are always thinking about improving the rotation on our farm where husband Jon Cherniss grows organic vegetables and soil tests indicate our rotation is maintaining or building organic matter.  I am emphasizing rotation here because we don’t have animals and use very little compost or manure.  We were both impressed by how well our soil stood up to the rains this year as we watched the neighbor’s soil and residue pile up on the road.  We do have tile drainage and off set our environmental guilt with the knowledge that improved tile and carefully managed surface drainage have spared spring crops during 3 of the past 4 years.  

  Our field of spring brassicas after intense rains.  PICS

 A neighbor’s field on the same day.  This is (was?) not a waterway.

Our spring crops were planted into fallow ground that followed fall crops.  Getting covers incorporated in time for summer crops was a challenge but we were lucky with the rains and confess a bit aggressive with the spader.  By adding all the organic matter with tillage soils resist or quickly recover from any damage.  While we are pleased that spading covers in during spring to prepare beds doesn’t seem to be compromising soil quality, we are concerned that it is exposing us to certain kinds of weed pressure.  Legume covers like hairy vetch or field peas are mowed before incorporation with a spader. 

We can use in-row cultivation for some crops but not others and can follow the spring crop with a summer fallow or smothering summer cover.  The presence of a crop or a cover crop prevents us from tilling as much one would want to control thistle.  Time constraints and rain prevent us from tilling frequently enough to control things like purslane so we need to find a way to mulch.  This is why rollers are once again piquing Jon’s interest.  So, even though we are trying to achieve more with rotation than our conventional neighbors, we share an interest in incorporating reduced tillage into our system.  Getting from the mulched phase of a rotation to a clean seed bed ready for spring greens will be another challenge.  So what about a cost share program for organic growers?

            The Agricultural Management Assistance Program, authorized by the Federal Crop Insurance Act in 2002 has allocated funds to reimburse producers for organic certification costs.  The new farm bill includes $22 million with five years of guaranteed funding to cover up to 75 percent of the cost of certification with maximum annual cost-share eligibility of $750 per farm.  This cost share defrays certification expenses- not organic production costs.  It currently costs growers over $70 an acre to plant hairy vetch. This is what it would cost to apply nitrogen fertilizer at 150 lbs per acre.  So, the diverse rotation turns out to be a deal for the downstream public while organic farmers are substituting effort, land area, and time for purchased inputs. We devote 50% of our land area to soil building crops instead of cash cropping it each year.  Even with this, we are probably too small to make it worthwhile to fill out and apply for a 23$ per acre cost share for covers if it were available.  Now paying us back for the price of certified cover crop seed might fit the bill. 

Achenbach, J. Iowa Flooding Could Be and Act of Man, Experts Say. June 19, 2008. Washington Post: http://www.washingtonpost.com/wpdyn/content/story/2008/06/19/ST2008061901432.html; and http://blogs.dmregister.com/?author=1894 accessed July 19, 2008.

Gowda P.H., Mulla D.J., Jaynes D.B. 2008. Simulated long-term nitrogen losses for a midwestern agricultural watershed in the United States AGRICULTURAL WATER MANAGEMENT    95 616-624.   
Jiang X.B., Huang C.H., Ruan F.S.  Impacts of land cover changes on runoff and sediment in the Cedar Creek Watershed, St. Joseph River, Indiana, United States 2008. JOURNAL OF MOUNTAIN SCIENCE   5:113-121.   

Kladivko EJ, Frankenberger JR, Jaynes DB, Meek DW, Jenkinson BJ, Fausey NR 2004. Nitrate leaching to subsurface drains as affected by drain spacing and changes in crop production system JOURNAL OF ENVIRONMENTAL QUALITY  33:1803-1813.    

Miguez F.E., Bollero G.A. 2006. Winter cover crops in Illinois: Evaluation of ecophysiological characteristics of corn CROP SCIENCE   Volume: 46:1536-1545.

National Agricultural Statistics Service (NASS); http://www.nass.usda.gov/index.asp

Pielke, R.A. Jr. Downton MW., Barnard Miller J.Z.  2002. Flood Damage in the United States, 1926–2000; A Reanalysis of National Weather Service Estimates; NOAA. http://www.flooddamagedata.org/use_interpretation.html; accessed July 2008).

Singer J.W., Nusser, S.M. 2007 Are cover crops being used in the US corn belt?
JOURNAL OF SOIL AND WATER CONSERVATION 62: 353-358.

Zhang YK, Schilling KE 2006. Increasing streamflow and baseflow in Mississippi River since the 1940 s: Effect of land use change JOURNAL OF HYDROLOGY 324:412-422.