TABLE OF CONTENTS Pages Symposium 1 - the National Sea ...

and the polyphenol content (Northup et al., 1999). Organic matter quality decreases as C:N
ratio, lignin, and polyphenol content increase. When earthworms mix and aerate the system,
the carbon source and C:N ratio have a significant impact on the rate earthworms bioprocess
the mixture. Switchgrass, oak, and willow are more desirable than barley straw, hybrid poplar,
and pine, for example and C:N ratios less than 30 also reduce and delay bioprocessing by
earthworms (Adler, unpublished data). Some carbon sources sequester N more rapidly than
others, such as willow, leading to greater conservation of N. Standard farm soil tillage
equipment can also be utilized to mix the organic soil instead of relying of earthworms. If
tillage is the favored management system to mix and aerate the system, carbon source and
C:N ratio may not be as critical. In either system, solids can be applied using standard farm
equipment, such as a vacuum tank spreader for solids followed by surface application of the
carbon layer to minimize vector transmission and volatilization of odors and N. Both systems,
whether relying solely on soil ecological processes for aquaculture solids stabilization or
tillage, farm labor and capital investment are minimized compared to alternative strategies.
Agroecosystems using biological management of soil fertility, strive for synchronization of
nutrient release with plant demand (Woomer and Swift, 1994) to not only increase the
nutrient use efficiency, but also reduce the potential for loss to the ground and surface waters.
With a C:N ratio of 20-30, water soluble N should be minimized (Stevenson and Cole, 1999).
However, P sequestration in manure amended compost is N limited due to the low N:P ratio
of manure. Water soluble P can be sequestered by having a higher C:P ratio. Net
immobilization of P occurs when C:P ratio is >300 and net materialization when