Guidance on Agroforestry System Design
Guidance on System Design
What practices work together? What are the design elements used for an agroforestry system? Tables 1 and 2 provide an overview of individual agroforestry systems to help answer these questions and provide a link to the National Handbook of Conservation Practices (NHCP) and the Field Office Technical Guide (FOTG). The NHCP and FOTG are maintained by the USDA, Natural Resources Conservation Service. Specific systems within a table may be found by referring to the list below.
Table 1. Row-Types:
Table 2. Block-Types:
The NHCP establishes official names for all conservation practices and sets national standards for each practice's design. The FOTG further refines each practice standard for use in a particular state. The agroforestry types listed in the tables are named by the predominant tree/shrub practice in the System.
Planning Considerations for Systems
For a farmer or rancher to adopt an agroforestry system, he or she must be both able and willing to incorporate rows or blocks of trees and/or shrubs in individual fields or units. The landowner must understand the new system, concur with its relative advantage to the operation, and be able to incrementally install and maintain the required practices. The landowner must also be aware of the time it takes for the trees and shrubs to grow and their silvicultural or management requirements. Interim systems to achieve objectives may be necessary for the first 5 to 10 years while trees and shrubs become functional. The use of equipment and chemicals (particularly herbicides) may require a greater level of control to prevent harm to crowns, stems and roots. For woody plants that will be harvested or yield products, the landowner will most likely have to acquire special marketing information and techniques. Properly designed agroforestry systems offer many benefits to farmers, ranchers and the public.
Some Definitions
Block-Types (Agroforestry System): Types of agroforestry systems consisting of agronomic or forage practices with an integral tree or shrub practice that is arranged in a block or rectangular pattern (the width or short axis of the block typically greater than 100 feet).
Row-Types (Agroforestry System): Types of agroforestry systems consisting of agronomic or forage practices with an integral tree or shrub practice that is arranged in a row-type or strip pattern (the width of the individual strips typically less than 100 feet).
Density (windbreaks and row-type plantings): Density refers to the percentage of the "background" scene that is blocked from view when standing away from the planting and looking perpendicular through it. "H" refers to the expected height of the tallest tree or shrub row in the planting at a specified or base age, usually 20 years in temperate climates and 10 years in tropical areas. The term "5H," for example, refers to the calculation of multiplying the constant, 5, times the expected height at the base age.
