Many thousands of acres of reclaimed surface mined land in Eastern and Southeastern Ohio are currently producing forages used for hay and pasture. The stands consist primarily of the cool-season grass species with tall fescue predominating. Older tall fescue stands usually are of Kentucky 31 strain and many are significantly infected with the endophyte fungus Acremonium coenophialum. Most recently established ones have been seeded using one of the newer, improved endophyte-free tall fescue varieties.
Ohio research has identified: (1) best minesoil types for forages, (2) fertility-management to optimize yields, and (3) some of the limitations of forages grown on minesoils. This research has centered on land reclaimed to modern standards as mandated by state and federal legislation enacted in the 1970s. Much of the land mined before that time was only planted to trees and generally possesses very low forage production potential. Nitrogen availability and the seasonal amount and distribution of precipitation are the dominant factors governing forage yields from minesoils.
Bethesda, Fairpoint, Farmerstown, and Morristown are the four of six Ohio minesoil types considered best suited for forage production. Of the recommended four, greatest variability of seasonal growth has occurred with the more acidic Bethesda. However, it has been very productive with fertilization during seasons with ample precipitation. Barkamp and Enoch minesoils are very acid, and even with fertilization will scarcely maintain vegetative cover. Most forage root growth on minesoils occurs in the thin zone of mixed topsoil-subsoil placed over the deeper, mixed spoil material.
Nitrogen (N) has proved to be the most limiting plant nutrient influencing forage growth on minesoils. Highest experimental yields, however, were consistently achieved with complete N-P-K fertilization. Nitrogen applied annually at 200 lb/A increased yields three-fold compared to those from the no fertilizer treatment, while this rate of N plus 100 lb/A of phosphorus and potassium increased yields about fourfold.
A yearly rate of 125-150 lb/A actual nitrogen, split applied, will provide economical yield increases with tall grasses grown on reclaimed surface mine land. Boosting the yearly rate to 175-200 lb/A N will further increase the yield potential, but at decreased efficiency per pound of additional applied nitrogen.
Dividing nitrogen applications (50% early-mid April and 50% after first harvest) will maximize the efficiency of this key element. Split applications increase N efficacy because: (1) the nitrogen supplying capacity of the mixed topsoil-subsoil is about one-third of natural soils, and (2) the physical properties of disturbed minesoils result in greater denitrification losses where all N is applied at one time in the spring. Fertilization following current soil test recommendations will provide adequate phosphorus, potassium, the secondary elements, and micronutrients for forage growth. Match soil fertility of the minesoil to the requirements of the forage species seeded. (See forage sections, Bulletin 472, "Ohio Agronomy Guide," 13th edition; and Extension Bulletin 2567, "Tri-State Fertilizer Recommendations.")
Legume plant stands typically are lost on minesoils within three to four seasons after reclamation even without nitrogen fertilization. Certain high-lime Morristown soil sites will retain birdsfoot trefoil, crownvetch and sometimes even alfalfa longer. Significant soil phosphorus buildup from 16 annual applications without nitrogen at two research sites did not sufficiently increase the legume component in the stand to match grass yields with 100 lb/acre per year of actual nitrogen. Nitrogen, with or without P or K, essentially eliminates legumes from grass-legume stands, although trace amounts of clovers will periodically volunteer.
Tall fescue yields on fertilized minesoils averaged 90% of fescue yields from nearby similarly fertilized undisturbed natural soils (data from 40 site-years). Unfertilized minesoil yields (due to low soil N release rate) produced only 55% of nearby unfertilized fescue grown on natural, undisturbed soil.
In Ohio's coal region, many farmers harvest initial spring growth from reclaimed land as hay or silage and then utilize subsequent regrowth (aftermath) by grazing or by a second hay harvest. Winter-spring soil moisture accumulation and spring precipitation usually ensures ample first growth, but the amount of regrowth is highly dependent upon subsequent precipitation and temperatures.
Older stands of tall fescue should be tested for percentage endophyte fungus infection. Testing will assess possible endophyte fungus influence on the performance of animals and will indicate how to best manage the forage. For more information on fescue toxicosis and testing for the endophyte fungus, refer to Fescue Toxicosis, AGF-008 available at Ohio State University Extension offices.
Grazing management of minesoil forage is slightly more challenging than grazing natural soil in two respects: (1) matching animal numbers to the more variable season-to-season regrowth to prevent either overgrazing or forage underutilization, and (2) to minimize soil loss from erosion due to overgrazing and from development of paths on slopes or tramping by animals near water sources and mineral feeders. Ohio studies on Fairpoint minesoil with 200 lb/A N had a long-time average of 175 animal unit grazing days (AUGD) per acre of regrowth following first harvest, but a low of 72 during the drought of 1988 and a high of 368 in the wet 1989 summer. The more acidic Bethesda spoil had an average AUGD per acre of 136 with the same 200 lb/A N. It had zero AUGD in the drought year and 324 in 1989.
Forage establishment recommendations on minesoils differ in three respects from those formulated for seedings made on natural soil:
Other agronomic and insect control recommendations for natural soils are applicable to forages grown on minesoils.
All educational programs conducted by Ohio State University Extension are available to clientele on a nondiscriminatory basis without regard to race, color, creed, religion, sexual orientation, national origin, gender, age, disability or Vietnam-era veteran status.
Keith L. Smith, Associate Vice President for Ag. Adm. and Director, OSU Extension.
TDD No. 800-589-8292 (Ohio only) or 614-292-1868