Fragipan Remedation

  • Murdock, Lloyd (PI)

Grants and Contracts Details


The fragipan is a naturally occurring soil horizon that virtually stops water movement and root growth through the soil. Its’ depth averages about 20-24 inches below the soil surface. The layer is due to the cementation of the soil particles with a silicate rich amorphous aluminosilicate binding agent. The fragipan is present in about 2.7 million acres of Kentucky soils and about 50 million acres in the U.S. Fragipan soils reduce yields of crops for 2 reasons: 1) limited water holding capacity due to limited soil depth (2) water saturated soil conditions during wet periods. The research on the fragipan has made excellent progress. There are two plants, potentially 4 compounds and possibly other materials that have been found to be effective in breaking apart the fragipan. They are annual ryegrass, festulolium, potassium chloride, potassium sulfate, sodium fluoride, sodium nitrate and possibly leonardite humate. Annual ryegrass was chosen as the central focus of the greenhouse and field research due to its notable advantages. Annual ryegrass roots apparently contain exudates that have a degrading effect on the fragipan. The deep root penetration degrades the fragipan and it also increases soil porosity and enrichment of organic compounds in the fragipan undergoing degradation. We gained enough confidence in the ryegrass treatment as a fragipan remedy and its yield increase potential. Fields in Kentucky, Indiana and Tennessee that had a history of annual ryegrass was found to have the upper part of the fragipan being degraded which resulted in deeper rooting. An organic compound has been identified in the ryegrass root exudates which induce the fragipan degradation. This may greatly aid in this effort and may lead up to a quicker and more effective method to remediate the fragipan. The average yield increase in 2019 of corn and soybeans from six field trials ranged from 0.5% to 20% for an annual ryegrass cover crop compared to no cover crop. The average yearly increase of corn grown after an annual ryegrass cover crop on a fragipan soil in southern Illinois is 3.7 bushel per acre per year over a 15 year period. The increase is accumulative resulting in an increase of 55 bushels per acre the 15th year. It appears that it might be possible to increase yields of corn and soybeans by 25% on the fragipan soils over many years by using an annual ryegrass cover crop. We also expect to improve the yields of wheat. A 25% increase would result in $500,000,000 in increased returns to Kentucky producers per year or $5,000,000,000 over a 10 year period on the 1.5 million acres of cropable fragipan soils in Kentucky. This does not include any increase that would be realized in forage production from the deeper soil. 2020-21 Objectives 1) Use my last year to finalize much of the on-going research. 2) Work with John Grove on possibly continuing some or all of the research. 3) Execute the field day in Hickman County on the Jerry Peery Farm that was rescheduled due to the virus. 4) Collect final data from the many field research trials. 5) Assist an Ag company to establish ryegrass/fragipan initiatives in several states with fragipan soils. 6) Assist a USDA-ARS scientist group to establish a fragipan research program based on our research. 7) Write as many research information pamphlets as possible on the only research information that exists on this subject.
Effective start/end date9/1/2012/31/21


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