Page 314 - Advances In Productive, Safe, and Responsible Coal Mining

290 Advances in Productive, Safe, and Responsible Coal Mining

native soil because of the important physical, chemical, and biological properties it
possesses; properties that are not characteristic of mine spoil derived from rocks. Soils
contain organic matter and essential nutrients, such as nitrogen and phosphorus, which
are essential to plant growth. Salvaging and respreading the native soil, where avail-
able, will supply a mine soil that contains a viable seed when spread fresh, and will be
favorable to native plant establishment and natural ecosystem development through
the process of ecological succession.

14.3.8.1 Liming, fertilizer, and mulch
Liming materials neutralize soil acidity and add calcium, a macronutrient essential to
plant growth. A soil pH between 6.0 and 7.0 is recommended since this is the range
where plant nutrients are most available and toxic elements are less available. How-
ever, liming is not always essential especially when reforestation is the land use goal.
Trees will grow well in soils of 4.5–5.5 pH, the pH of native forest soils.
Fertilizers containing nitrogen, phosphorus, and potassium (N, P, and K) are gen-
erally applied to the soil when reclaiming mine sites because most mine soils have
relatively low amounts of organic matter, which is the primary reservoir for N and
P in soils. Fertilizer recommendations for pasture grasses require large amounts of
N and P for establishment and growth. Hence, a common fertilizer prescription for
hay and pasture postmining land use would be 672kg/ha (600 pounds/acre) of
10-20-10 fertilizer. This amount of fertilizer will provide 67kg/ha of N, 134kg/ha
of P 2 O 5 (equivalent to 59kg of elemental P), and 67kg/ha of K 2 O (equivalent to
59kg/ha of elemental K).
Forestry postmining land uses require a different fertilizer prescription. Generally,
forested postmining land uses require less N than hay and pasture uses. Larger
amounts of P, however, are often recommended to support the planted trees’
longer-term growth requirements. Burger et al. [65] recommend that 30kg/ha (40
pounds/acre) of N and 40kg/ha (52 pounds/acre) of elemental P should be applied
as fertilizers when establishing forests. This can be achieved by applying 180kg/ha
(400 pounds/acre) of 18-46-0 (diammonium phosphate); by applying a blend of
90kg/ha (200 pounds/acre) of 0-60-0 with 135kg/ha (300 pounds/acre) of 19-19-
19; or with other fertilizer mixes.
Mulch improves forage and tree establishment on mined land by reducing water
loss through evaporation and increasing infiltration, augmenting surface soil temper-
ature extremes, protecting the soil from erosion through absorbing rainfall impact
energy and holding soil particles together, and minimizing soil crusting [86]. Mate-
rials used as mulch include organic mulches (sawdust, bark, wood chips, animal
manure, hay and straw, compost, and other litter materials); inorganic mulches (plas-
tic, rocks, and other durable cover materials); chemical soil stabilizers (which form a
protective film or cover to bind particles); and preparatory and vegetative or nurse
crops (annual grains). The use of organic mulches is especially desirable because they
have the potential to add organic matter to the soil, which helps to provide a reservoir
of plant nutrients and aids in water-holding capacity. Application rates depend on soil
properties and the slope of the land, but generally 1.5–2 tons per acre (3.4–4.5t per