Uses of cover crop residues: A.No-till (NT)—cover crops are killed and retained as a dense, uniform mulch over the entire field. NT is difficult because: Cover crops must be mechanically killed before planting. NT systems require specialized equipment for plant establishment and weed management.

Uses of cover crop residues: B. No-till, living mulch (NT-LM)—cover crops are killed only in the areas (zones) where cash crops are grown (grow zones); cover crops are keep alive (living mulch) in the alleyways during the growing season. NT-LM is difficult because: Cover crops must be mechanically killed in grow zone areas. Specialized NT equipment is required to establish cash crops. Living mulch in alleyways must not encroach or shade cash crops.

Uses of cover crop residues: C. Green manure, zone-till (GM-ZT)—cover crops are shallow incorporated in grow zones; cover crops are either killed or keep alive in alleyways. GM-ZT is relatively easy because: No specialized equipment is required for zone tillage and plant establishment. Weeds in grow zones can be managed using conventional methods.

Uses of cover crops: D. Green manure, conventional tillage (GM- CT)—cover crop residues are shallow incorporated over the entire field. GM-CT is easy: Conventional equipment is readily available. Weed management can be achieved using mechanical cultivators.

Conclusions: Although there are many associated challenges, organic-CA systems can produce the best of both worlds—high crop yields, improved soil quality, and many emergent or synergistic properties such as pest suppressiveness and crop quality. Success with organic CA can be achieved when selecting well- suited environments and following recommended practices; examples include: Fertile soils with low weed populations (many crops) Fall crops (broccoli); staked or erect growing crops (tomato) Crops forming rapid, dense leaf canopies (squash- and cabbage-family species) GM-ZT systems, using simple conventional equipment (many crops)