Polyculture Farming Techniques: Maximizing Diversity by Design

Images courtesy of Apolonio Mai, wildbze.com

The prevailing modern worldview sees farms as treeless monoculture businesses, and our forests as either lumber and paper, or tracts to be left undisturbed, preserved, and protected. This traditional worldview stems, in part, from the “myth of the pristine forest,” a longstanding opinion that the earth’s most magnificent, ancient forests have not been touched or interfered with by humans, when in fact this is far from the case.  Scientists have shown that even forests that have previously been considered pristine, like the Amazon, have long been marked by considerable human activity.[1]  This information should encourage us to increase our interaction with the environment to actively combat the incredible destruction humans have caused to the earth’s forests with regeneration that is modeled after the balanced natural systems themselves. 

We have cut down 99% of the earth’s old growth forests in the past 500 years so that only 1% remains and have created massive destruction to the environment by mismanaging it over the past 300 years.  When we look at the forests that remain on earth, most are not healthy, mature forests, but rather the remnants of what has managed to survive years of human destruction.  Most of the forests that remain are depleted, fragmented, and suffering, and as a result we are seeing an increase in die off and disease.  The more we destroy our ecosystems in this manner, the more unpleasant it becomes for us to live. We believe it is our responsibility and privilege to intelligently reforest and manage our environments in a way where significant portions of our earth thrive in perpetuity. 

Permaculture sees forests as vast resources that can be thoroughly worked without degradation and farms as multi-layer polycultures with a vast proportion filled with tree crops.  Polyculture involves growing more than one crop in the same cultivation system. It is one of the principles of Permaculture and useful techniques include crop rotation, agrofrestry, companion planting, intercropping, and succession planting. By creating multi-layered polyculture systems, we are able to grow much more in smaller spaces, in a healthier, more disease and pest resistant manner that more closely mimics the diversity found in natural ecosystems. 

AGROFORESTRY

Agroforestry is a collective name for land-management systems that optimize the economic and ecological benefits created when trees and/or shrubs are integrated with crops and/or livestock.[2]  These techniques give home gardeners and large-scale farmers a competitive advantage over conventional agricultural methods.  The benefits that agroforestry techniques provide have been well documented, including:

• Healthier, abundant, thriving forests
• More efficient and balanced living areas for humans and wildlife
• Increased yields
• Greater diversity of products increasing economic opportunities and stability for farmers
• Dramatically increased biodiversity
• Improved soil
• Improved watersheds
• Decrease in pest-related problems
• Increased protection from wind, erosion, etc., and offsets for drought and flood cycles
• Reduced carbon-dioxide heading into the atmosphere
• Dramatically increased biodiversity
• Alternatives to environmentally destructive practices for forest-dependent communities

Two examples of agroforestry systems are:

• Silvopasture where livestock, forage pasture and trees are integrated into one system which provides food for livestock who in return keep the weeds down, and
• Orchard alley cropping where nitrogen-fixing trees are interspersed with the orchard trees to increase soil fertility resulting in a more productive orchard.

Because agroforestry requires intimate knowledge of tree, shrub, and crop interactions, we are dedicated to a lifetime of learning and field testing various agroforestry techniques to determine the best ways to incorporate them into whole-systems design solutions for the problems we, and forest-dependent and rural community members most commonly face. 

INTERCROPPING

Examples of nitrogen fixers and common green manure vegetation (left to right): Kudzu, Myrica faya,Trifolium incarnatum, Vicia villosa (a.k.a., Crimson and Clover (more than just a great song))

Intercropping is the practice of cultivating two or more crops together, usually by growing the additional crops in the spaces available between a main crop that has greater importance to the farmer because of a high dietary demand for it, or for economic reasons such as crop sales.  Intercropping increases biodiversity and enables farmers to produce greater yields by utilizing space that would otherwise be wasted.

Different types of intercropping include:

• Planting a fast growing crop with a slow growing crop
• Planting a shallow-rooted crop with a deep-rooted crop
• Planting a tall, sun-loving crop with a shorter, shade-loving crop
• Mixed intercropping: Crops are completely mixed throughout the available space
• Alley cropping: Component crops are arranged in alternative rows
• Strip cropping: Multiple rows, or strips, of one crop are alternated with multiple strips of another crop
• Multi-tiered systems:  A popular example of this for the tropics is growing coconut trees (upper tier), with bananas (middle tier), with ginger, pineapple, animal fodder, aromatics, and medicinals (lower tier)

Our test plots at the center are designed to test combinations for different microclimates, soil requirements, crop varieties, and space available so that crops benefit one another rather than compete for nutrients, water, or sunlight.  

COMPANION PLANTING

Companion planting is a technique of planting two or more crops in close proximity to one another so that the unique natural substances in or emanating from the plant roots, leaves, flowers, etc. may provide some benefit to one or all of the other plants. Some combinations are meant to deter harmful pests, while others attract beneficial insects. Certain combinations rely on dynamic accumulators, and still others on edible nitrogen fixing species.  Some combinations may provide other important nutrients, support, or shade, while others enhance the flavor or growth rate of their companion crops.  

Although this technique has been used for centuries, there is still a great need for collecting and sharing evidence from field tests for various types of companions and their effectiveness for what they attempt to achieve in different bioregions, soils, etc.  Therefore, we have incorporated hundreds of popular combinations into our garden plan so we can do testing in the field, and share the best results with our community members as part of our community outreach projects. 

SUCCESSION PLANTING

Succession planting helps gardeners and farmers to use garden space efficiently by capitalizing on the varying times it takes plants to ripen. Some plants need a very short time to ripen, while others take months. By staggering plantings, harvests are spread out and help extend growing seasons, ensure continuous harvests, and help farmers dodge pesky pest problems.

There are several different methods of succession planting that anyone can incorporate into their garden plots, such as:

• As soon as one crop is harvested, the space is replanted with a different crop. Using flats or raised beds for cover crops and seed starts helps farmers to take advantage of any space that opens up after a crop is harvested with seedlings that are ready to be planted.
• Fast growing plants can be planted in succession, spaced a few weeks apart to ensure continuous harvest of high demand plants such as salad greens. 
• A single planting of many different cultivars with varying maturity times can be planted together to ensure continue harvest over longer periods of time

Our garden test plots incorporate succession planting in many different ways so that we may test and fine-tune best practices for gardens at the Center as well as for our community outreach projects.