Black Energy: cultivar of life

Black Energy

“Land, then, is not merely soil; it is a fountain of energy flowing through a circuit of soils, plants, and animals.”

Aldo Leopold

Most living things depend on the Earth’s skin, soil, for life. Soil is made up of native rocks (45%), organic material (5%), air (25%) and water (25%) but its essential components are clay minerals, humus, as well as plant and microbe metabolites. Plants rely on soil for mechanical and life support, a thermal buffer, a habitat that provides its essential symbiotic organisms, as well as a source of water, toxin neutralizer, and nutrient supply. Clay minerals along with small plant and microbe metabolite molecules provide most of the soil’s nutrients. These chemicals are vital for the conversion of sunlight into energy for plant metabolism, which is responsible for growth. Nitrogen, phosphorus, and potassium are the three major plant nutrients. Soil nutrient levels are determined through soil testing.  Soil analysis will provide the levels of pH, N, K, and P in the soil, as described in a previous post, Tend the Soil .

Plants absorb nitrogen from the soil through their roots in the form of either nitrate ions or ammonium ions.  The absorbed nitrogen is used by the plants  for incorporation into amino acids, nucleic acids, and chlorophyll. Excess nitrogen, can result in rapid, lush growth and a diminished root system. Prairie plants depend on their extensive root system for survival so excess N levels should be avoided.

Many restoration ecologist have also found that fertilizers, specifically increased nitrogen, N, promote competitive invasive species growth in prairie restoration projects. Prairie plants do not need additional nitrogen so there is no need to fertilize them. However, plant growth can be improved with the use of inoculants (microorganisms) but seek the advice of your prairie seed supplier before adding these to your soil.

Soil particularly high in nitrogen can be amended by incorporating organic matter, like straw, into the soil. Cultivation of the organic matter into the soil will reduce the excess nitrogen available to weed and invasive plant seeds. It is however, important to make sure the organic matter is herbicide, grass, and weed seed free. Contact your local University Extension Service for more information on nitrogen reduction in soil.

Clay or humus rich soils act as chemical buffers for a wide variety substances present in the soil that might be responsible from an unfavorable pH. The soil’s buffering property can be either an asset or a detriment to soil depending on how much acid, alkali, pesticides, oil, water, and ions stored in its reservoirs.  Positively speaking, these buffers stabilize the soil against abrupt chemical or physical changes that may adversely affect a plant’s growth. However, the buffers can also store large amounts of undesirable substances, resulting in chemical alteration of the soil’s properties.  Remediation of chemically altered soil properties is a difficult and lengthy process requiring the addition of lime and sphagnum peat or organic mulch for acidic and basic soils, respectively.

Salts containing calcium (Ca2+), magnesium (Mg2+), and potassium (K+), and sodium (Na+) cations are commonly found in soil. The earth’s crust is often the origin of these salts. However, salts also result when rocks weather and their dissolved ions have been carried away by water and deposited on the soil’s surface or accumulate in underground water. Fertilizers, organic amendments, and water runoff also add salts to the soil.

Soil salts dramatically affect soil structure, porosity, and plant-water relations. Decreased soil and plant productivity are a result of increased levels of soil salts. Specifically, seeds will fail to germinate or germinate slowly, and plant growth will be slow and stunted in high salinity soil. High salt concentration in soil will cause the plants to wilt and die, no matter how much they have been watered, because the plant- root salt ion concentration becomes unbalanced, interfering with its ability to effectively draw water from the soil.

Salt affected soils are commonly found in areas where evaporation exceeds precipitation and resulting dissolved salts accumulate, or in areas where runoff or vegetative changes have caused salts to leach and accumulate in low-lying places or areas with low water tables. Soil testing that includes a detailed salinity analysis is required to determine what type of salt build up, if any, is present in your soil. Contact your local University Extension Service for more soil testing information. In Illinois, contact one of the following soil testing labs for information regarding salinity testing capabilities, sample collection protocol and remediation recommendations.

With soil salinity results in hand, one will definitively know whether their soil is salt affected. If the soil analysis reveals a high buildup of salt concentration, the soil will fall into one of three salinic categories: saline, saline-sodic and sodic. The easiest soils to correct are the saline soils; sodic soils are more difficult. Accumulated salts can have adverse effects on soil function and one of the following means can accomplish management and soil remediation:

  • improving soil drainage;
  • leaching salts from the soil with excessive watering;
  • applying mulch to reduce evaporation rate of the soil’s water content;
  • chemical application to reduce the exchangeable sodium content in the soil; and
  • combination of these methods.

Phosphorus, P, the last of the three major plant nutrients to be addressed in this post is also found in soil and water, as well as all living things. This essential nutrient is required by plants and animals for proper energy utilization. Plants use dissolved orthophosphate from the soil. Usually, soil P levels are naturally low. Extreme P deficiencies, determined by soil testing, can be remediated with the addition of either inorganic phosphorus containing fertilizers available from treated rock phosphates or organic phosphorus sources found in animal manures. However, caution must be used when adding additional phosphorus to the soil because industrial and municipal point source discharge and agricultural and urban nonpoint source runoff of phosphorus has resulted in an explosion of competing, nonnative plant populations and algal blooms on nearby streams, lakes and rivers.

 All plants have the basic nutrient needs of nitrogen and phosphorus.  F. Stuart Chapin has found that the nutritional characteristics of wild or native plants are similar to those required by herbaceous crops from fertile habitats. The growth rates for both groups are relative to their nutrient supply. However, native plants respond to moderate nutrient stress through increased root absorption to compensate for the limiting nutrients as well as developing an increased root to shoot ratio, a decreased photosynthetic rate, and decreased reproductive output.

Chapin has found “…where light and water are not unduly limiting, extremely nutrient-deficient sites are dominated by slowly growing stress-tolerant species, nutrient-rich sites by rapidly growing competitive and ruderal species, and intermediate sites by a combination of the two and by plants with intermediate characteristics.”  Native plants have adapted to infertile soils, in fact, this environment is acceptable for these stress-tolerant species, whose slow growth rates are maintained by their low nutrient absorption. Native plant species have the ability to maximize soil nutrients by maintaining a large root biomass and symbiotic relationship with the fungus, mycorrhizae. The slow growth rate of the native plants enables them to maintain nutrient reserves, which helps them to survive periods of low nutrient availability. That being said, it is best to review your soil testing results with your local University Extension Service for soil remediation recommendations.

Soil Testing

Soil Samples

Soil testing results for several sample sites of our restoration project were as follows:

Sampling Area ID #

Date of Sample

Type of Plant Growth

pH

Nitrogen (N)

Phosphorus (P)

Potassium (K)

Feel Test

Comments

1

4/3/12

dandelions, natives, buckthorn

7

low

low

very high

humus odor, fibrous but silky, sticks together when moist

loamy organic

2

4/3/12

dandelions, natives, buckthorn

7

very low

very low

high

floury texture when dry, clod forming

loam

3

4/3/12

Bishop’s wort, natives, buckthorn

7

low

low

very high

dry, clod forming

loam

4

4/3/12

Vinca, thistle, day lily

7

low

low

very high

dry, barely forms to clod when moist

sandy loam

5

4/3/12

Red osier dogwood, grass

8

low

low

high

smooth texture, forms ball when wet

clay

Based on the testing results above, the soil of our restoration site was treated for low nitrogen. To amend the low nitrogen levels, native Purple prairie clover plants, that naturally add nitrogen to the soil, were planted in the restoration area. In addition to treating the low nitrogen content of the soil, the low phosphorous level was also addressed. A small amount of cow manure was added to each hole dug for a native plant plug in a sampling area of the restoration sight. Soil remediation is only recommended when soil testing results indicate an extreme nutrient deficiency that would jeopardize the root development of native plants. Before amending your soil consult your local University for remediation recommendations.

Resources
Buckholtz, Daryl D. and Brown, J.R. Potassium in Missouri Soils. University of Missouri Extension, Oct. 1993. Web. 14 May 2012.
Chapin III, F. Stuart. “The Mineral Nutrition of Wild Plants.” Annual Review of Ecology and Systematics, Vol. 11. (1980), pp. 233-260.
Carroll, Steven B. and Salt, Steven D. Ecology for Gardeners. Timber Press, Inc. Portland, Oregon. 2004.
 Everhart, Eldon.  “How to Change Your Soil’s pH.” Horticultural Home and Pest News. Iowa State University, University Extension. 6 Apr. 1994. Web. 1 May 2012.
 McCauley, Ann.  Jones, Clain. and Jacobsen, Jeff.  “Basic Soil Properties.” Soil and Water Management I, Montana State University Extension Services. 2005. Web. 2 May 2012.
Provin, Tony. and  Pitt, J. L. ” Managing Soil Salinity.” Texas A & M University System. AgriLife Extension. N. D. Web. 19 May 2012.
Sharpley, Andrew. Daniels, Mike. VanDevender, Karl. Slaton, Nathan. “Soil Phosphorus: Management and Recommendations.” University of Arkansas Division of Agriculture.  University of Arkansas Cooperative Extension Services. N. D. Web. 19 May 2012.
Schulte, E.E. and Kelling K.A. “Soil and Applied Potassium.” Understanding Plant Nutrients. University of Wisconsin-Extension, Cooperative Extension. N. D.   Web. 18 May 2012.
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3 Comments

  1. Basic Horticulture Needs | UH Gardens
  2. Relationship of Air and Water in the Soil | UH Gardens
  3. The Ingredients of Soil « Gardora.net

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