Farm Transitions: Valuing Sustainable Practices—Soil Fertility Management

Adding livestock manure, either from animals on the farm or purchased nearby, is a common practice on fields in the Midwest. Eventually, that organic material breaks down and becomes stable soil organic matter (SOM). Good SOM levels allow less use of purchased fertilizer and other purchased soil amendments. Good SOM levels also help drought-proof the soil. SOM is like a sponge: it absorbs up to six times its weight in water (1). Increasing SOM helps the soil retain and hold water that can be used by crops (see Value of Soil Organic Matter text box).

It does make a difference whether manure or synthetic fertilizers are used to manage soil fertility. According to the Leopold Center for Sustainable Agriculture at Iowa State University, “Manure is a biologically active substance; synthetic fertilizers are not. Since soil is a living system itself, with millions of living organisms in each spoonful, it will react better to manure than to synthetic fertilizers (2; see Your Living Soil text box).” Synthetic fertilizers are produced using fossil fuels, so if reducing fossil fuel use is an important part of the vision for the future of your farm, then encouraging use of manure for fertility is an important option to consider. Manure produced by large confined animal feeding operations (CAFOs) and by small farms can become a problem and a pollutant unless it is spread on land as a fertilizer, using good management techniques. Encouraging use of manure as fertilizer is a way to turn a potential pollution problem into a good resource for crop production (see Nutrients in Manure text box).

Manure application is something that many cash grain farmers choose not to do because it takes different equipment and requires more labor and management than use of purchased synthetic fertilizer. Synthetic fertilizer has specific, known amounts of each nutrient in it. Manure is more variable, so farmers who use it need to get it tested to learn the nutrient levels and then make calculations of the amount of manure needed. Sometimes synthetic fertilizer may be needed in addition to the manure, to balance the levels of each nutrient needed by the crop that will be grown. That means the farmer may need to run two different sets of equipment across the fields, to apply the manure and the synthetic fertilizer.

How can a landowner make it possible for future landowners or operators to use manure for fertilizer? Using manure is generally cheaper overall than using synthetic fertilizer, so manure use is not likely to be a financial burden for the farmer. In a few cases, the distance to a source of manure may raise transportation costs to the point that its use is not feasible. The main drawback to manure is the time and management effort that the farm operator needs to invest in it. Synthetic fertilizer doesn’t take as much time and management.

As with crop rotation, the choice to use manure depends partly on the determination of the landowner and the farm operator to use it. Both farm operator and landowner need to understand the benefits of manure use and agree to use it on the farm. The landowner may consider giving the farm operator a credit for the manure management efforts that contribute to long-term soil health. Specifying manure use can be accomplished through lease terms, and can be done with either an annual cash rental situation or a longer-term lease. See Conservation Financing for more details about lease terms.

Use the Manure Management Cost/Benefit Table to estimate the value of using manure as fertilizer on your farm.


References:

(1) Organic Matter Management. In The Soil Management Series. Revised 2008. Ann Lewandowski. www.extension.umn.edu/distribution/cropsystems/components/7402_02.html (accessed 6/11/13).

(2) Frequently Asked Questions about Cropping System Diversity and Profitability. [online] Leopold Center for Sustainable Agriculture, Iowa State University.
www.leopold.iastate.edu/faq-cropping-system-diversity-profitability. Accessed 6/10/13.

(3) Dairyland Laboratories Manure Packaging & Pricing.
https://www.dairylandlabs.net/pages/m_packaging_pricing.php

Further Resources:

Soil Health, Profits & Resiliency. This Land Stewardship Project web page features ways Midwestern farmers are building soil organic matter and other biological attributes of their soils using cover crop cocktails, managed rotational grazing, perennial plant systems and no-till agriculture.
www.landstewardshipproject.org/stewardshipfood/soilquality

Sustainable Soil Management. 2004. Preston Sullivan. Appropriate Technology Transfer for Rural Areas (ATTRA).
https://attra.ncat.org/attra-pub/summaries/summary.php?pub=183
This publication covers basic soil properties and management steps toward building and maintaining healthy soils. It contains answers to why soil organisms and organic matter are important.

Drought Resistant Soil. 2002.Preston Sullivan. Appropriate Technology Transfer for Rural Areas (ATTRA).
https://attra.ncat.org/attra-pub/summaries/summary.php?pub=118
To minimize the impact of drought, soil needs to capture the rainwater that falls on it, store as much of that water as possible, and allow for plant roots to penetrate and proliferate. These conditions can be achieved through management of organic matter.

Soil Health. 2010. John Lamb, Sheri Huerd, and Kristine Moncada. In Organic Risk Management, Editors Kristine Moncada and Craig Sheaffer. University of Minnesota.
www.organicriskmanagement.umn.edu/soil_health.pdf (accessed 8/30/13)
This online manual is intended as a guide for organic and transitioning producers in the Upper Midwest, but it includes a lot of good basic agronomy and soil science information that is useful for non-organic farmers as well.

Soil Fertility. 2010. John Lamb, Kristine Moncada, and Craig Sheaffer. In Organic Risk Management, Editors Kristine Moncada and Craig Sheaffer. University of Minnesota.
www.organicriskmanagement.umn.edu/soil_fertility.pdf (accessed 8/30/13)
This online manual is intended as a guide for organic and transitioning producers in the Upper Midwest, but it includes a lot of good basic agronomy and soil science information that is useful for non-organic farmers as well.

The Cost of Soil Erosion. January 2013. Iowa Learning Farms, Iowa State University Extension and Outreach.
www.extension.iastate.edu/ilf/sites/www.extension.iastate.edu/files/ilf/Cost_of_Eroded_Soil.pdf (accessed 8/30/13).
Erosion costs the landowner because of lost farmland productivity and potentially decreased land sales price. This study is reported by the Iowa Learning Farms, which is a joint project of many of the agricultural organizations in Iowa; including Iowa State University, the Leopold Center for Sustainable Agriculture, and the Iowa Department of Agriculture and Land Stewardship.