Permaculture

There are many principles of permaculture which aim to make all aspects of life ecologically sustainable. Home construction, production of food and other goods are done in such a way as to minimise work by observing and following the laws of nature.

Bare soil is avoided, traditional cultivation and tillage is avoided and soil disturbance is minimised.

Fertilisers are generally avoided with the exception of manure and other mulches. This is good as it has been found that they can kill or inhibit AMF.

Emphasis is placed on growing perennial crops such as trees, bushes and perennial herbs (see agorforestry page). Most permaculture plots meet the criteria for encouraging glomalin formation; no digging and a wide variety of permanent plant roots. The soil in forest gardens and other perennial gardens is usually high in carbon and fertile.

The use of biochar in permaculture systems is also on the increase.

In most instances permaculture practices are found to optimise conditions condusive to AMF.

It is when it comes to growing annual vegetables that permaculture systems sometimes fail to meet the criterai for sustainability and for AMF proliferation.

If annual crops are grown, they tend to be grown through a mulch of, for example, straw or manure. Although the soil is protected from erosion and carbon loss that result from digging and is fertile, there are however problems associated with this practice.

Straw is usually grown with soluable fertilisers in soil which has been ploughed. Apart from this it is high in carbon, low in nitrates and therefore the benefits in terms of enabling no dig are worth it.

Manure, on the other hand, is high in nitrates and low carbon and is often from animals fed on grass grown with soluble fertilisers. Manure decomposes easily and the nitrates are easily lost to the ground water or atmosphere if used as a surface mulch. For this reason, organic standards require that no more than 12 tonnes per acre of manure is applied (not enough to use as a mulch) and that it is incorporated into the soil (rather than applied to the surface as a mulch) where it is better protected.

In small scale gardens and allotments, the problem occures on a smaller scale. If fields were to be heavily mulched with manure, the scale of the problem would be much more noticable. Run off from manure is as toxic and polluting as that from other fertiliser use. If the manure applications are very heavy, the run off and loss to the atmosphere simply increases accordingly.

As it is so high in soluble fertilisers, manure has detremental effects on AMF.

A better alternative, if it is freely available, is composted ramial chipped wood (RCW). (See ‘Jean Pain Method‘).

If manure is used, being a freely available agricultural byproduct, that manure can be mixed with biochar, covered and left to compost before application. The biochar will adsorb some of the otherwise soluable nutrients in the mulch and thereby reduce pollution and increase bioavailability of the nutrients. (At least 20% biochar has been found to stabilise around 50% of the nitrates in the manure).

Current organic management requirements are that the manure should be covered in a building or under plastic sheeting or tarpaulins in order to prevent nutrient loss whilst it is composting. My preference, instead, is to cover it with a crop of green manure (plants grown to be dug back in). The intention here is to encourage glomalin production in the manure pile whilst it is composting.

Whether the manure is then used as a mulch or is incorporated into the soil, at least as much carbon has been stabilised as is practical. Again, my preference is to incorporate it into the soil rather than to use it as a mulch and to limit the amount used used. I would then use a mulch (ideally of RCW composted with biochar) to further protect the soil and manure.