Fruit and Nut

Introduction

Permaculture is a design system for sustainable land use.The word itself - permaculture - was first used by Australians David Holmgren and Bill Mollison in 1978 but derives from permanent agriculture, a term used by Joseph Russell Smith in the late 1920s to describe nut and fruit crops raised for human or animal feed. During the middle and latter part of the twentieth century, the term permanent agriculture became synonymous with forest farming, though actually the two are not the same. For example, in regions with cool temperature climates, and particularly those at relatively high latitudes (for example Ireland or Britain), almost no cultivated variety of fruit or nut will crop well in a true forest situation. Cultivated forms of nuts and fruits require good levels of light (and sunshine) and good ventilation, conditions that are not found in forests.

Over time, the concept of permaculture  has been expanded to include many social and environmental aspects, for example ecological design, sustainable building and integrated resource management. On several occasions, Bill Mollison attempted to claim copyright or trademark rights to the word permaculture. These attempts were eventually abandoned, probably with the realisation that ideas cannot be copyrighted. In any case, permaculture is not an original idea, simply a representation of the evolution of ideas derived from older forms of agriculture. In tropical and sub-tropical regions, permanent agriculture involving the tending of tree crops has been practiced for thousands of years, if not tens of thousands (in New Guinea). However, part of Mollison's interest in creating a trademark was driven by concerns that the credibility of permaculture was being compromised by the adoption by some so-called permaculture practitioners of non-scientific practices (for example practices based on astrology or ritual).

Core Tenets

In spite of continuing disagreements among practitioners about what constitutes permaculture, there is generally consensus on the core tenets:

Care for the biosphere

Care for the people (provision of the resources necessary for people to meet their needs)

Reinvestment of waste/surpluses

Design Principles

In addition to the core tenets, David Holmgren identified twelve design principles that he attributed to permaculure. These are listed below:

Observe and interact

Catch and store energy

Obtain a yield

Apply self-regulation and accept feedback

Use and value renewable  resources and services

Produce no waste

Design from patterns to details

Integrate rather than segregate

Use small and slow solutions

Use and value diversity

Use edges and value the marginal

Creatively use and respond to change

Alternative Design Criteria

In place of Holmgren's twelve principles, some of which are vague or ambiguous, Fruit and Nut has adopted the following alternative permaculture design criteria, with each principle subservient to the previous one:

Sustainability: the system (the farm, the community, the region) must function in a way that is sustainable of time

Optimal use of the resources available: land, plants, microclimate, people, animals, nutrients, materials, water, renewable energy. In particular, optimising solar energy and nutrient capture by plants and minimising loses from the system (optimal recycling of resources). In wet climates such as Ireland, optimal use of water nearly always involves water shedding (removal of surplus water from the system).

Optimising useful outputs: food, materials, energy, skills, knowledge, resilience (for example, resilience to climate change)

Minimising outside inputs: energy, materials, nutrients, water (exceptions to this would be people and knowledge)

Minimising complexity* (although at first this might seem counter-permaculture, it's based firmly within the realities of what is actually possible. Nature is never unnecessarily complex. Keep it simple. Complexity can always be increased at a later date, if desired)

Adapting and evolving as required

*and if you live in a cool maritime climate and want to grow staple foods, forget forest gardens: they really don't work

Zones

One of the more useful  permaculture concepts is that of zoning. Zoning is a way of intelligently organising land use based on the frequency of human use and plant or animal needs.

Zone 1 represents the land zone nearest to human habitation. In this area would be the elements of the design that require the most regular intervention or maintenance.  At the other end of the spectrum is zone 5, the wilderness, where human  intervention is close to zero. Among disciples of permaculture, there is considerable disagreement about the appropriate location for fruit or nut trees, with each of the five zones having their particular advocates. However, it is the view of Fruit and Nut that the level of intervention required for successful production of fruit or nuts is frequently underestimated.

Based on climate, disease and other practical considerations, our recommendations are as follows:

Zone 5: The wilderness
Unsuitable for fruit and nut trees, except native trees grown solely for biodiversity

Zone 4: The semi-wilderness
Mostly unsuitable for fruit trees and all nut trees requiring regular management. Possible exceptions would be be holm oaks (for acorns), araucaria and pinus pinea grown as large stand alone trees. However, this area would be suitable for fuelwood production and could also provide material for mulching.

Zone 3: The outer cropping area
Generally used for production of staple food crops, for example grains and other field crops. Suitable for the larger growing nut trees, particularly those not requiring regular maintenance and management.. Peripheral parts within this zone can be used for providing materials for mulching.

Zone 2: The inner cropping area
Used for higher maintenance food crops. This is the optimum zone for fruit and nut species requiring regular attention during the cropping season (for example cobnuts and most tree fruit) and also most berries, and also for field crops requiring a higher degree of attention. This may also be the most appropriate location for trialling and research projects where regular inspection and data gathering is essential.

Zone 1: Environs of habitation
Used for food crops requiring the highest level of attention.  At the nursery we grow outdoor squashes within this zone. Generally not appropriate for fruit or nut trees but may be the best location for key research projects or for trees requiring optimum micro-climates. Berries prone to bird predation (for example blueberries) may also be best here.

Zone Designation Modification

Zone designation should not be viewed as permanent. Where circumstances on land change - for example greater inputs of human energy or improvements in site insfrastructure - perhaps part of the semi-wilderness (Zone 4) may be redesignated as integral to the main cropping area (Zone 3). In certain circumstances, for example a community with an aging population, the opposite may apply, with a higher emphasis on production within the inner zones.

This section was updated 06/10/20

Other Applications of Zone

The zone concept can also be used clearly identify different categories of land within a site, for example to grade land according to the ease of development. This system is used at Fruit and Nut. The grading system runs from A to E.

Zone A is designated as the part of the site that is easiest to develop while Zone E is the hardest. In many instances, Zone A will be found to coincide with permaculture Zone 1, but it is not always the case. However, there is a certain logic in designating Zone E as the wilderness area.

Ease of development may be contingent on many factors: access; soil type, moisture content, depth, compaction and acidity; aspect; degree of shelter; previous land use; and the resources available.

Edge

Another permaculture concept is edge. Edge refers to the transition zone between different habitats, for example the area to be found along the banks of a river.  Here is often found the greatest biodiversity and the greatest levels of nutrient and energy exchange. Edge is often a useful resource for the fruit and nut grower, for example in the supply of mulching materials or in providing the most benign micro-climate (or most favourable topography) for trees requiring optimum environmental conditions.

Some examples of edge are given below:

Stream and river banks

Lake shores

Coastal regions

Boundaries of cultivated areas

Edges of boglands

Margins of woodlands

Roadside verges and railway embankments

Transitional zones between different altitudes, soils types or microclimates

Margins of settlements

Diversity and Productivity

Diversity

In natural ecosystems there is generally a natural progression towards species diversity over time. When the ice sheets retreated from northern Europe at the end of the last Ice Age, the bare land was first colonised by mosses and lichens, then herbaceous plants, then dwarf species of shrub and tree and finally the species of large trees. While the total number of living species - flora, fauna and micro organisms combined - typically continues to increase into the latter phases of plant succession, the actual number of plant species may sometimes peak then fall as large tree species become dominant.

Diversity is nature’s insurance policy against something going wrong. If one species succumbs to a disease or some other environmental factor, another will quickly fill that niche.

Permaculture seeks to emulate the diversity found in nature through the practice of polyculture: the simultaneous nurturing of multiple species of plant or animal on the same piece of land.

Complexity

Over time the general trend of natural ecosystems from simple communities towards more complex ones. Examples of this can be found in the colonisation of virgin land after some catastrophic event such as a volcanic eruption, or a more gradual ones such as the retreating of icecaps following the ending of an Ice Age. Essentially, nature is involved in a huge trial and error experiment. Many of the early pioneers will be forced out by later arrivals, or pushed into margins. Forest fires or other one-off events may wipe out many species and wind the clock back to an earlier time.

Permaculture is evolving too. At present it is at the early colonisation stage. The greater complexity found in mature natural ecosystems may also be found in permaculture landscapes in 500 or 5000 years time. But for now, permaculture needs to be relatively simple. A sterile landscape deliberately colonised with only a dozen plants and a dozen microfauna species would soon have hundreds of unique interactions between different species. But soil already contains countless species, at bacterial level the figure could run into thousands if not millions. No one even knows. The potential number of unique interactions between different species is beyond our ability to comprehend. Within this seething cauldren of biological activity the permaculturist now attempts to impose a new dynamic, one geared to meeting our basic needs. But if anything is to be learned, the changes have to be carried out gradually. Nature cannot be replicated overnight.

Productivity

Productivity can be measured in many different ways. With natural ecosystems, it generally refers to the total dry biomass production over a given period of time. With managed ecosystems, sometimes only the usable output is measured. In both cases, productivity reflects inputs, for example solar energy, water and nutrient supply. The most productive natural systems tend to be in wet tropical regions or in areas of very high nutrient availability such as the fringes of estuaries.

There is a widespread misconception that diversity always means higher productivity. In actual fact, the highest plant productivity (calories of dry biomass weight produced over unit of time) is frequently found in monocultures, for example in plantations of sugar cane or fields of alfalfa.

Of course, in the majority of cases the high outputs from monocultures are only achievable because of the massive inputs of artificial fertilisers, pesticides and herbicides (and indirectly,  inputs of fossil fuels).  Although the optimisation of useful outputs is an objective of permaculture, this has to be interpreted in the context of the long term sustainability of the whole system.

Climate

Climate is the word used to describe long-term trends in meteorological phenomena such as temperature, precipitation, humidity, wind, and atmospheric pressure. Weather, by contrast, refers to short-term conditions of these variables within a given region. A weather forecast makes predictions - based on the information available, including previous weather history -  of what the weather will be in the coming days.

Climate Classification

The world’s climates are generally classified into five main groups. Within these groups there are 12 or more sub-groups

The main groupings are as follows:

Tropical:                               Tropical Wet
                                                Tropical Wet and Dry

Hot:                                        Arid
                                                Semi-arid

Moderate/Temperate:        Mediterranean
                                                Sub-tropical
                                                Maritime

Continental:                         Warm Continental
                                                Cold Continental

Polar/Alpine:                        Mountain
                                                Tundra
                                                Ice cap

Even within the subgroups there is a wide range of climatic variation.  For example, the maritime temperate climatic region of Europe extends from south-west Norway to northern Spain, and from western Ireland to south-west Germany. Other parts of the world with the same climate classification include New Zealand, the coastal fringe of southeast Australia and a small region of North America’s Pacific coast around Seattle and Vancouver. Within these regions, some extremely large variations can be found.

Many parts of Victoria state, Australia (the birth place of permaculture), have an average daily maximum temperature of 27º C or above during the summer period, with the highest absolute temperatures in excess of 46º C. The figures for Dublin are 19.3º C and 31º C respectively.  Melbourne receives almost 2200 hours of sunshine per year, compared to Dublin’s 1450.
And from a food-growing perspective, the Dublin area has one of the most benign climates in Ireland!

Comparisons between Ireland and Northern California, North America’s new permaculture capital, are even more stark. Much of this region has a climate that is classed as warm Mediterranean. Sacramento city, situated in the lower Sacramento valley, receives around 3600 sunshine hours per annum. This is significantly sunnier than Seville, Lisbon or Marseille.

From an agricultural perspective, success is not just about temperature or sunshine hours, though obviously those are important.  Availability of water is a critical factor too. In places like Sacramento or Seville or Melbourne, water conservation is the issue. In Ireland the problem is mainly to do with having too much! 

In cool damp climates, where both evaporation and transpiration rates are low, high rainfall causes many difficulties: cold anaerobic soils that are unfriendly to roots and which can easily be damaged further through careless work; increased risk of plant disease; poor conditions for pollination or for ripening fruit.  In warm dry sunny climates, recommended best practice is to plant close. Shading is often beneficial. But in cool, damp and relatively sunless climates, the opposite applies. Providing lots of room between plants allows maximum exposure to solar radiation. It also improves ventilation, which is critical in reducing disease.

Regardless of which climate the grower has to work with, the key to getting the best out of it is to know it intimately: to understand its particular limitations and know which measures may be taken to help.

The Irish climate

The principal geographical and topographical polarities that influence the Irish climate are listed below:

East versus west

In relative terms, east is dry, west is wet and the middle of the country is somewhere in between. Most weather systems come from the Atlantic and when they hit land they drop rain. All other things being equal, the counties of the west coast get fifty or sixty percent more rain than the east.

South versus north

South is warmer, north is cooler, although from an agricultural perspective the differences are generally much less significant than between east and west.

Lowland versus mountain

Lowlands are warmer, sunnier and drier. As air gets pushed up over high ground it cools, causing water vapour to condense and fall as rain. Temperatures generally fall with altitude, typically 0.5-1ºC with every 100 metres gained. Higher ground is also more exposed to wind, which can also reduce air temperature (for example when ground-warmed air is blown away and replaced by colder air. The warmest growing conditions are generally found below 150 metres.

However on clear calm nights, cold air adjacent to the ground will flow downwards to the lowest point. On these nights, the coldest air will be found in valley bottoms around dawn. Such locations can be very prone to late spring frosts (a major limiting factor for many tree crops).

Inland versus coastal

Coastal areas, being influenced by the temperature of the sea, tend to be milder in winter but cooler in summer. Temperature variations between day and night are smaller than at inland locations too. Hard frosts are either unknown or very rare. Exposure to prevailing winds can be a limiting factor, particularly on west and south-facing coasts.

Inland areas generally have warmer summers but colder winters. Some very sheltered locations may experience occasional frosts as late as June.

Information on micro-climates will be added to this section in the near future

Water Balancing

Water balancing is a term used by Fruit and Nut to describe the optimal use of water within managed ecosystems.

Water inputs include precipitation from rain and snow, natural seepage or percolation by gravity from higher ground or horizontally by capillary action from adjacent river systems lakes or wetlands, and also irrigation.

Outputs include transpiration, evaporation, percolation through the soil, drainage into streams and rivers, plus water extracted for other purposes.

Ireland has a very different climate to Australia, where permaculture principles were first devised. In Ireland, water inputs from precipitation (or precipitation plus water ingress from higher ground) frequently exceed combined evaporation losses and transpiration requirements, so unless the surplus can be adequately removed from the land, waterlogging results.

Any agricultural activity that causes compaction - for example the repeated use of heavy agricultural machinery or having inappropriate livestock densities for the prevailing ground conditions - will compromise soil percolation and contribute to the problem of waterlogged soil.

Waterlogged soils are unsuitable for all species of fruit and nut, and in varying degrees, eventually become unsuitable for most other agricultural activities too.  The key to successful use of land in Ireland is water removal, not water retention (though that can be important during springtime and summer when evaporation and transpiration combined can sometimes exceed rainfall).

Although Ireland’s high rainfall is potentially a limiting factor is terms of what can successfully be grown, waterlogged soils are the far bigger problem. And while the rainfall is something we have to accept and work with, the waterlogged soils are a factor that can be changed (or avoided in the first place, through appropriate use of land), through drainage and also also by increasing water extraction by trees and other plants. Drainage on its own will lead to nutrient losses, something the sustainable farmer will be anxious to avoid. Where possible, drainage system design should include features such as reed beds or sediment traps, that enable nutrient capture and recycling.

Carbon Balancing

Objective

An essential goal for the permaculture management strategy of any piece of land should be carbon neutrality. In essence, this means that all associated carbon costs (including the external lifestyle costs of the inhabitants) should be offset by carbon sequestration on site.  

Carbon sequestration is term given to the process of carbon capture from the atmosphere and its long term storage. The simplest and most viable method involves natural biological processes: essentially the accumulation of carbon-rich plant fibre (woody material) and the formation of stable carbon compounds within soils. In essence, sequestration can be summarised in three words: plant more trees. An aspirational balancing target in terms of sequestration might be 5 -7.5 tonnes of additional woody biomass per capita per year (though up to 17 tonnes in some cases), or its equivalent carbon capture in soil.*

Certain remedial works, for example drainage activities or large scale composting, may add to carbon emissions.

* this figure is based on the average per capita carbon expenditure in Ireland or the UK: approx 7-7.5 tonnes per annum (also close to the EU average). In some countries, for example Australia and the United States, the per capita expenditure is more than 100 percent higher, at around 17 tonnes. In Bhutan, the corresponding figure is only 0.7 tonnes. More info here

1 tonne of carbon dioxide contains 0.272 tonnes of carbon. This fraction is broadly similar to the proportion of carbon contained in live tree tissue. Air dried timber contains approximately 50 percent carbon.

Digging and No Digging

The main principle behind no digging is that of mimicry: to replicate what happens in the natural world. In nature, soils build up incrementally over time. Within the evolving soil, distinct layers form with the most fertile and most biologically active layer at the top. Once a soil is dug, these layers become disturbed or destroyed.  With industrial scale tillage using tractors and other machinery, damage also occurs to soil structure: for example compaction and the formation of impervious pans, or the oxidation of organic material.  A further risk of excessively tilling soils is increased vulnerability to erosion, from either wind or water.

While the general arguments in favour of no-digging are clear, these need to be tempered with the realisation that in nature, soils can take thousands or even tens of thousands of years to form. In cold northern latitudes, the process of soil formation is incredibly slow, as little as a few millimetres per century. Such soils tend to be very nutrient poor. And as soils form, they will be colonised only by the plants best adapted to that particular environment.

Cultivated plants are generally very particular in their soil requirements.  For example, they will generally not succeed in very shallow mineral soils over impervious bedrock or glacial clay, or in highly acid soils or in soils that are waterlogged for months on end, or in soils low in nitrogen or other nutrients.  Many cultivated plants have originated in warmer and drier climates and may already be close to their climatic limits in Ireland, meaning they will have greater vulnerability to things going wrong. For most cultivated plants, including most if not all edible tree crops, unmodified native soils in cool temperate regions are generally deficient in depth, percolation, nutrients or in some other limiting factor, or possibly in all of them. 

Over the course of the long history of agriculture, people learned how to improve soils through activities such as drainage, the adding of amendments (to increase fertility), and the undertaking of major earthworks such as terracing and the building of mounds. And as tools evolved from ones made from wood to ones of iron then steel, digging became part of the repertoire of activities people could engage in to improve soils: for example to excavate materials from elsewhere to add fertility or bulk to their cultivated soils, or to break up hard or impervious subsoils to increase depth and improve percolation, or simply to work soils to a sufficiently fine tilth to sow seeds.

Digging and No Digging should be viewed as two sides of the same coin. They both have a role to play. Digging is often essential to the initial development of a soil intended for cultivation purposes.  Digging can accomplish in a season or two what nature might take five thousand years to achieve.  However, once required depth or desired percolation is achieved in a soil, no digging or Less Digging may become the default mode. If a no digging regime can be maintained only by the importation of very large quantities of materials (for example, industrially manufactured compost or mulch) to help increase soil depth, improve fertility and assist with weed control, then probably the wrong strategy of land stewardship is being pursued.

As far as the cultivation of nut or fruit trees are concerned, deep digging should be regarding as an essential part of ground preparation. Only where deep, well drained and fertile soils already exist, is it advisable to plant without first carrying out remedial work.

Utilising elevation

In a permaculture context, elevation simply means height, or height difference.  With height differences, a number of factors come into play, for example micro-climatic variations based on altitude or on pitch and direction of slope, or the influence of gravity in draining away water (and cold air). 

The differences in elevation do not have to be large for there to be a measurable effect. Where there is a high water table, a rise of the equivalent of only one spade depth could make the difference between having 30cm of aerated soil and having none. 

Gravity

Gravity causes water to flow downhill to the lowest point. Gravity enables wet land to be drained and high water tables lowered, potentially making the land more viable for agriculture, particularly for crops with deep roots. And because cold air is denser than warm air, gravity also causes cold air to flow downwards, which on a clear spring night might enable an orchard to escape frost damage.  On clear nights with no wind, the coldest air will be found in the bottom few metres of a slope, or in the flat bottoms of a valley, with the coolest air down near ground level. Armed with this knowledge, the sustainable farmer can plant nut and fruit trees on relatively elevated land, above the place where the cold air settles. As little as two or three metres can make a difference. Regarding both air and water, the most important rule concerning gravity is to work with it, not against it.

Gravity also causes soil (and other materials) to migrate downhill, which means that when digging or ploughing on a slope, great care should be taken should be taken to ensure that the soil stays in situ.

Aspect

Aspect is the direction a slope faces. Southwesterly, southerly and westerly aspects will generally be more exposed to prevailing winds. Southerly aspects and all other aspects with a southerly component will receive higher amounts of solar radiation and will warm quickly in spring. While this might appear beneficial, sometimes this can be a disadvantage as some trees may leaf or flower too early and then be vulnerable to spring frosts.

Northerly aspects are generally cold but are often very sheltered from prevailing winds.  When the sun is high they can sometimes be warmer than an exposed southerly aspect.

Flat ground

Flat open ground is potentially exposed to wind and may require supplementary shelter. Flat ground - even well elevated ground - is vulnerable to rapid cooling on still clear nights. However, elevated ground is typically more exposed to wind than lower ground, meaning more air mixing takes place. This may help mitigate cooling on clear nights.

Pitch

The pitch, or angle of a slope, will tend to accentuate aspect.  For example, a steep southwesterly aspect is likely to be very exposed to prevailing wind, while a steep north facing slope will receive almost no sun.

Steep slopes can be challenging to use, but also offer exciting possibilities for terracing.  In many parts of the world, terraces are used for nut and fruit tree cultivation. There are fine examples of fruit terraces (and in some places, nut terraces) along the banks of many of Europe’s great rivers, particularly the Rhine. The construction of terraces is very energy intensive and can have major impacts on adjacent land. It requires very careful planning and is best undertaken during the early stages of site development.

Scheduling

Scheduling is the collective term for the organising and carrying out of essential activities on the land. The style of scheduling employed may vary considerably between different agricultural practices and groups. For example it can operate from within highly a rigid timetable structure (such as having fixed planting dates/times for specific crops) or be a model of flexibility that takes into consideration the resources available and environmental factors such as weather and ground conditions.

Within the last eighty or ninety years, a new style of agriculture - known as biodynamic - has developed, based on the teachings of philosopher Rudolf Steiner. While based on organic principles, the Steiner school of agriculture also adopts a number of more esoteric or ritualistic practices: for example the burying of animal horns filled with dung in the centre of fields. Biodynamic agriculture uses a scheduling system based on the astrological  calendar, with particular reference to the moon constellation. Steiner was not an agriculturalist nor did he practice any form of farming: his ideas on agriculture came entirely from his philosophical beliefs of how the world should be.  Nevertheless his ideas found an audience and after his death in 1924 were taken up by his followers. Critics argue that biodynamic agriculture has no methodological validity and in that respect is no different from other faith practices. However, for those who do believe in its powers, it undoubtedly provides a useful working structure. It is mentioned here primarily to illustrate the difference between more rigid and more flexible scheduling systems (see below*).

* The examples given are simplifications and do not illustrate the full range of possibilities. For example, some faith-based agricultural societies have proved highly flexible in adapting to changing circumstances.

Time Horizons

The table below gives an indication of the time horizons for various aspects of permaculture and food production

* a small number of tree species are capable of living longer than this

Potential for Food Production

All sorts of wild and unsubstantiated claims have been made regarding the food-growing potential of permaculture systems over conventional agriculture. The reality is, if Ireland stopped importing food (which accounts for 60 percent of food currently eaten in Ireland), abandoned conventional agriculture and switched to permaculture tomorrow, most people would starve. To feed itself, Ireland would require the food equivalent of more than one million tonnes of grain per annum, and that presumes all the grain would be used for feeding people not livestock.

In the short term at least, some form of contemporary agriculture (albeit with some major structural changes) is almost certainly a more viable option. Permaculture systems take many years to develop. Even with incentives and motivation, the realistic lead time for converting Irish agriculture to permaculture would probably be 30-50 years. And as permaculture has never been practised in genuine crisis conditions, nor detailed trials undertaken, no-one really knows what level of outputs are achievable. Much would depend on the level of skills and knowledge within the community, the availability of seed stock, nursery-raised trees, and the right breeds of livestock, and the ability of people to make massive changes in lifetyle. These limiting factors would apply to contemporary agriculture too, but the knowledge and skills base would be significantly broader.

Preliminary research by Fruit and Nut suggests that Ireland could meet 12-16 percent of its dietary requirements from tree crops. Although achievable, this is probably close to a best-case scenario. However, the total food yield from fruit and nut orchards could be boosted significantly by incorporating animals - for example pigs, sheep or geese - that would graze underneath the trees. More information is here

Regarding the potential total food outputs from an agricultural system run primarily on permaculture lines (ingetation of trees crops, animals, perennial and annual field crops) there is no real evidence to suggest either calorie or protein outputs would be significantly higher than other forms of micro-managed sustainable agriculture. Claims made that permaculture could feed many times the number of people supportable by other systems of agriculture are based on magical thinking, not science.

Limits to productivity

On oft-repeated permaculture mantra is that 'the yield of a system is theoretically unlimited, or, limited only by the information and imagination of the designer'. However, when interpreted from an agricultural perspective this is simply not true. The output of a system can never exceed its inputs - which in agriculture means available solar energy, carbon, water, nitrogen and other plant nutrients - or at least not for very long.

Limits to output will always be imposed by whichever resources are in the most constrained supply, for example solar energy for photosynthesis, essential plant nutrients, water availability, soil oxygen supply or heat energy to fire up biological processes. In a cool wet climate such as Ireland's, water availability is only rarely a problem. Limiting factors are more likely to be solar radiation, temperature, soil oxygen supply or the availability of plant nutrients obtained from the soil, subsoil, and air, or added as amendments.

The guiding principle for sustainable system of land use is simple: always seek to balance outputs with inputs.

Other Viewpoints

An amusing article by Ann Owen on the trials and tribulations of permaculture: The Trouble With Permaculture

More information on permaculture will be added in the near future (last updated (06/10/20)