Title page for ETD etd-11597-154323


Type of Document Dissertation
Author Kern, James Donald
Author's Email Address jkern@vt.edu
URN etd-11597-154323
Title Water Quality Impacts of Cover Crop/Manure Management Systems
Degree PhD
Department Biological Systems Engineering
Advisory Committee
Advisor Name Title
Wolfe, Mary Leigh Committee Chair
Alley, Marcus M. Committee Member
Bosch, Darrell J. Committee Member
Collins, Eldridge R. Jr. Committee Member
Mostaghimi, Saied Committee Member
Vaughan, David H. Committee Member
Keywords
  • water quality
  • manure
  • cover crop
  • injection
Date of Defense 1997-11-19
Availability restricted
Abstract
Crop production, soil system, water quality, and economic

impacts of four corn silage production systems were compared

through a field study including 16 plots (4 replications of

each treatment). Systems included a rye cover crop and

application of liquid dairy manure in the spring and fall.

The four management systems were: 1) traditional, 2) double-

crop, 3) roll-down, and 4) undercut. In the fourth system,

manure was applied below the soil surface during the

undercutting process. In all other systems, manure was

surface-applied. In the third system, the rye crop was

flattened with a heavy roller after manure application.

Simulated rainfall was applied within 48 h of manure

application. Measured constituent concentrations in runoff

were compared with water quality criteria. Costs and returns

of all systems were compared. The undercut system reduced

loadings of all nutrients, but increased total suspended

solids (TSS) concentration as compared with all other

systems. The mean volume of runoff from the undercut system

was less than half that from any other system, which

influenced all constituent loadings. Mean TSS concentration

in runoff from the undercut system was over three times the

mean of any other system. The roll-down system had no

significant effect on water quality as compared to the

traditional system. The undercut system was reasonably

effective in keeping phosphate phosphorus levels below the

criterion set for bathing water. None of the systems

generally exceeded nitrate nitrogen concentration criteria.

However, total phosphorus, orthophosphate, fecal coliform and

e. coli criteria for drinking, bathing, shellfish harvest,

and aesthetics were regularly exceeded by all of the systems.

There were no differences among the treatments in effects on

bacterial concentrations. The double-crop system produced

significantly higher net returns than all other systems only

if the value of the rye crop was $92.31/Mg or more. There

were no significant differences in net returns of the

traditional, roll-down, or undercut systems.

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