Caring for the Land

This post is the result of agricultural sustainability research paired with on-farm interviews conducted by The Clark Group, LLC with 12 farms utilizing these practices.  We hope this information can help begin the process of identifying sustainable practices for several key agricultural commodities, and help lead to a system that allows consumers to be connected to products containing these sustainably grown ingredients.

Land Care

Preserving the land's ability to grow crops year after year by protecting the soil, its moisture and nutrients.

Conservation practices that benefit soil and water quality include:

·       No-till or reduced tillage (pictured to the right): involves drilling down through the previous year’s stalks and leaves to plant the new crop.  Cropland is left unplowed between harvests.

·       Increasing the amount of crop residue from harvest: using equipment like the Shelbourne header which harvests grain high on the stalk and leaves behind a tall length of stalk residue standing on the field after harvest

·       Crop rotation: a process of growing different crops sequentially on a given field to ensure soil fertility is maintained since different crops require different nutrients from the soil

·       Cover cropping: involves growing a crop between regular commercial cropping periods for the sake of returning nutrients to the soil, holding soil in place and otherwise preventing wind and water erosion from a field

·       Reducing fallow periods: decreases the amount of time that fields are left uncultivated since a field with nothing growing on it is more susceptible to wind and water erosion

·       Reserving areas or field corners for grassland or other vegetation: fields are often irrigated using center pivot systems that leave field corners less productive.  Planting these areas to native grasses helps preserve the land and creates valuable habitat for wildlife.   

The significant amount of residue left behind by reduced tillage techniques creates something like a blanket that sits on top of the soil and holds in water, prevents fertilizer run-off and soil erosion from wind and water.  Ultimately this practice increases the soil’s strength and fertility over time. 

Preserving Water in the Soil

Conservation practices like those discussed above are also beneficial for lowering water and wind erosion and improving soil and water quality.  Crop residue on the field can also capture precipitation like rain and snow.  The effects of these conservation practices on water include:

§  Surface water quality improves because with less runoff the amount of sediment and sediment-bound chemicals carried in runoff is reduced[1]

§  Evaporation of water from the soil, and the need for water application, improves as practices like conservation tillage are effective at increasing soil water infiltration[2]

Reducing Greenhouse Gases

These conservation practices also have the ability to capture a major greenhouse gas, carbon dioxide, and store it as beneficial soil carbon in the ground. Plants and trees naturally convert carbon dioxide (or CO2) into carbon and give off oxygen.  The carbon is stored in their roots and deposited into the soil.  Because reduced tillage does not fully turn over the soil, it allows the greenhouse gases that have been stored in the ground to remain there.  Since this type of planting requires fewer passes through the field and less fuel-intensive machinery to plant crops, farmers utilizing no-till methods are also reducing the amount of GHG emissions created in comparison to farms that do not utilize these methods. 

In addition to reduced tillage practices, the other conservation measures discussed above also contribute to storing more carbon in the ground.  This is because plants take on this function naturally – therefore, any practice that improves the amount of plant growth on land or the length of time where plants are actively growing – is also improving the soil carbon content of the soil and reducing carbon dioxide from the atmosphere.  The chart on the following page provides an average snapshot of what many of these practices can do to reduce greenhouse gas emissions (GHG).  Since there are many different greenhouse gases containing varying degrees of global warming potential, standard practice is to convert all GHG into a measure called carbon dioxide equivalent or CO2e.    

Mitigation Potential for Crop Management Practices[3]

Change in management on existing croplands

Soil Carbon tons CO2e/ acre-1/yr-1

Average Net Impact,  tons CO2e/acre-1/yr-1

Maximum U.S. applicable area in millions of acres

Change in Tillage Practice (Conventional to no-till)

0.44

0.41

178

Change in Tillage Practice (Conventional to conservation till)

0.37

0.43

178

 

Eliminate Summer Fallow

0.19

0.13

49

Use Winter Cover Crops

0.34

0.61

183

Diversify Annual Crop Rotations

0.23

0.26

245

Include Perennial Crops in Rotations

0.23

0.31

138

Organic Soil Amendments (especially manure)

0.89

0.89

21

Switch From Dry Land to Irrigated

0.59

-0.14

n/a

Irrigation Improvements

0.14

0.48

49

 

Wildlife Habitat Enhancement

Reduced tillage and harvest practices also provide high quality wildlife habitat by creating food, water and shelter for wildlife that would otherwise not exist – especially during the winter months.  Studies have found that when stalk residue is high (greater than 15 inches) and left on the field, there is a significant increase in the benefit to wildlife habitat.[4]

Finally, because conservation agriculture is good for soil, it also improves crop yield and production.  Conservation practices keep existing farmland in peak production, which means less pressure is placed on converting new or virgin lands into agricultural use.

The Conservation Reserve Program (CRP) provides technical and financial assistance to farmers and ranchers to address soil, water, and related natural resource concerns on their lands.[5]  CRP is administered by the US Department of Agriculture (USDA).  The program encourages farmers to convert highly erodible cropland or other environmentally sensitive acreage to vegetative cover, such as grasses, wildlife plantings, trees, filter-strips, or riparian buffers.[6]  Farmers receive an annual rental payment for the term of a multi-year contract, and cost sharing is provided to establish these practices and compensate for the revenue lost as a result of not harvesting a crop on those acres.[7]

This program reduces soil erosion and sedimentation, improves water quality, establishes wildlife habitat, enhances forest and wetland resources, and protects the ability to produce food and fiber for the long term.[8]


 

Citations:

[1] Hill, P. R., & Mannering, J. V. (n.d.). Conservation Tillage and Water Quality. Retrieved from Cooperative Extension Service, Purdue University: http://www.extension.purdue.edu/extmedia/WQ/WQ-20.html.

 

 

[2] Hill, P. R., & Mannering, J. V. (n.d.). Conservation Tillage and Water Quality. Retrieved from Cooperative Extension Service, Purdue University: http://www.extension.purdue.edu/extmedia/WQ/WQ-20.html

 

 

[3] Alison, J. Eagle, R. Lucy Henry, P. Lydia Olander, Karen Haugen-Kozyra, Neville Millar, and Philip G. Robertson. Greenhouse Gas Mitigation Potential of Agricultural Land Management in the United States: A Synthesis of the Literature. Nicholas Institute for Environmental Policy Solutions, 2010.

 

 

[4] Rodgers Randy D., “Effects of wheat-stubble height and weed control on winter pheasant abundance.” Wildlife Society Bulletin Y. 2002, vol. 30, No. 4, pages 1099-1112.

 

 

[5] USDA NRCS. (2011). Conservation Reserve Program. Retrieved from www.nrcs.usda.gov/programs/crp

 

 

[6] Ibid.

 

 

[7] Ibid.

 

 

[8] Ibid.

 

 

 

 

 

 

 

 

 

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