Polydome Concept Overview V.3 Structural Features The longer lifespan of a Polydome greenhouse means that more effort should be invested in the quality and materials of the structure itself than is traditionally invested in a greenhouse. This life span also justifies investment in innovative structural features. Additionally, the structure should be easy to renovate, upgrade, and adapt to changing functions and technologies over time. The structural features we have envisioned should be designed to facilitate the key ecological features of the system, which maximize beneficial plant interactions and increase crop density. Spatial and Temporal Stacking In the Polydome system, each crop occupies a different “niche” in space and time, allowing for crop stacking and extremely high density production. Stacking in Space: • Companion planting allows for the dense planting of mutually beneficial crops that don’t compete for the same nutrients. The added benefits of companion plants are described elsewhere. • Vertical Stacking: Plants have different light requirements and root space requirements. We can take advantage of this fact by placing crops on top of one another; either planting tall and short crops together, or physically locating hanging plants above ground plants. Trellising: By encouraging plants to grow vertically rather than horizontally, we can increase • the amount of ground space available for other crops. This is already common practice, but can also be combined with natural trellising (on trees or other crops) for added crop density. Stacking in Time: • Succession Planting: Plant configurations change as certain key crops reach maturity. For example, trees begin as small plants with relatively low light and root space requirements. In these early stages they can be surrounded with other plants. Once a tree matures, it can be interplanted with a shadeloving cover crop, or left bare under its canopy. In the Polydome greenhouse, it is also possible to continue integrating new perennial crops over time to extend the productive lifespan of the greenhouse. For example, several years into production, new berry bushes or trees can be planted to reach maturity later than the first batch. • Continuous Cropping is the practice of planting small supplies of short-time yield crops in quick succession to extend the duration of the harvest. For example, quick-yielding beans can be planted repeatedly in short cycles. Rather than having a single large harvest, this results in continuous yields. This is particularly relevant in the hydroponics module, but can also be practiced in the annual soil modules. Space Sharing: Early season crops are intercropped with late season crops, allowing a single space to be used to its maximum potential by several rounds of yielding plants. • Crop rotation refers to the alternation of crops planted in a single location. This rotation is typically done once a season. It is a practice that must be followed for the sake of soil health (pest accumulation), and to avoid selective nutrient depletion. There are wellknown guidelines for which families are best for following each other with. Microclimates and Microzones The conditions inside most greenhouses are specifically catered to the particular plant under cultivation – lighting, humidity, fertigation schedules, and all other aspects of production are designed around that particular crop. In the Polydome system, the general conditions are catered to an “average” plant preference. To get more specific conditions per plant, microclimates and microzones are created through crop placement, in a way that echoes how plants in a natural environment find more optimal conditions by selectively placing themselves in specific niches. This approach reduces the need for many energy-intensive climate and atmospheric controls. However, because of the greenhouse’s unique design, it will be especially important to monitor key parameters such as temperature, humidity, root-level oxygen, light penetration, and atmospheric CO2 in different parts of the greenhouse. Polydome: High Performance Polyculture Systems 33 • Pagina 32

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