Making a Banana circle mulch pit compost garden
In the tropics, this is an ideal element to use and there should be one in every garden. Banana circles or ‘mulch pit gardens’ help create humus, provide water retention and build fertility on sandy or heavy clay soils. The banana circle can also be made with or without the compost bin and/or grey water supply.
The construction of this efficient garden is relatively straight forward:
– Dig a pit up to two meters in diameter and up too 1 metre deep. Total width should be 3-5m wide.
– Up to seven plants of the appropriate type are then planted in the rim of the pit. Taro or other moisture loving plants may be planted on the inside edge, and sweet potato along the outside edge to provide a living mulch as well as extra production.
– Grey water feed is just below surface level and comes in through the mound and drains into the mulch pit, through a 50mm ag pipe. (Be sure that you only use plant based soaps in your washing machine.)
– A large compost bin (with lid) is placed into the centre. Protected from vermin this compost can be filled with any organic matter that otherwise is not utilised in other compost systems (bokashi, worms or chickens)
Mulch pit gardens allow for the stockpiling of large amount of otherwise difficult to manage biomass in a
convenient location. The moisture conservation nature of the pit and stacked layers of biomass promote conditions for fungal, bacterial and insect breakdown of materials, as well as compost worms. This speeds up by many times the above ground breakdown cycle, producing humus in a time frame of months rather than years. Large and difficult to manage biomass, as well as thorny biomass can be included in the mulch pit garden. A mesh frame or large plastic compost bin could be placed into this space to keep the mulch more contained and aesthetic. When the banana plants have grown tall they then hold the mulch pile upright removing the need for a composting frame.
The critical component to successful management of such systems is maintaining the biomass of mulch within the compost bin. Filling with hay, mulch, prunings and grass clippings when possible. (Ask your neighbours for their grass clippings too.) The more organic materials in the pit the more bananas you will grow!