Polyculture systems are difficult to engineer, develop, and manage. It is common for designers to meet with mixed or limited success. Often, the individuals are knowledgeable and passionate about restoration ecology but have failed to integrate certain crucial elements into their design. The multidisciplinary nature of permaculture design necessitates a broad knowledge of natural history, ecology, horticulture, crop management, etc.; it is difficult to cover all the bases. During my travels and consultations I have encountered the same issues at multiple sites:
1) The design fails to capture the structure and architecture of natural ecosystems. Designs should utilize multiple canopy layers to ensure capturing the maximum level of available sunlight. Biodiversity should promote niche partitioning in order to ensure maximum nutrient utilization efficiency and to promote fertility.
2) Design fails to choose plants that suit particular area or microclimate. Neglecting native species falls into this category. Many people spend a lot of time creating berms and swales, hugelkultur, adding soil amendments, etc. It’s more efficient and natural to plant species that can thrive on the conditions that already exist on your site.
3) Design fails to incorporate an adequate number of soil building species. It is common to neglect legume diversity or perennials whose roots enrich the soil with carbon. Mismanaging harvests can also impact soil building.
4) Design fails to consider palatability of mixture and nutrient balance (e.g. forage protein). Poisonous species, especially legumes (more often eaten than other poisonous plants) should be avoided in polycultures that will be used for hay. Too many legumes will result in too rich hay, and too few a protein deficit. A balance must be reached between biodiversity, nutrient production, and hay production/harvest. Inputs should not be required.
5) Design fails to optimize productivity. Usually due to species and or nutrient imbalances. Failure to include key producers in the right proportions can severely inhibit productivity.
6) Design fails to produce secondary products such as hay, bees/honey, mushrooms, or medicinal plants. Secondary products can generate significant revenues and increase overall profitability and economic resilience.
7) Design fails to achieve levels of biodiversity adequate to produce “architecture effects.” Biodiversity must be significant in order to produce environmental services such as decreased disease prevalence, natural pest control, increased biodiversity, etc. Diversity should be not only intraspecific but also conspecific.
8) Design and managers failed to account for harvest dynamics. Species mature at different time periods; consideration must be taken regarding development of one species in contrast to harvest of another. System biodiversity may be negatively affected by inappropriately timed or scaled harvest.
9) Designers failed to incorporate an aesthetic element into system. Flowers that serve as forage for bees, food for beneficial insects, and landscapes that serve as pest and disease vector disruption; also serve to increase the natural beauty of the landscape. Visitors, customers, children, and the farmers themselves benefit from the valuable yet less tangible aspects of aesthetic incorporation. The beauties of permaculture systems also encourage people to adopt them.
10) Designers failed to incorporate a step fashion design. i.e. All the species were planted at once. Instead, species should be introduced in groups in that pioneer the new system structure. It is important these species be introduced in the proper order and in the environments that can support them. How can lower canopy species thrive if the upper canopy is not yet developed? How can the upper story develop when there is no ground cover stabilizing soil and maintaining moisture and fertility?