BIOPHILE 16 — JUNE/JULY 2007 R25 - Biophile Magazine

Soil for LifeSheet MulchGardeningBuild your soil the‘no work’ waySoil for Life is a Cape Town-based NGOwhich teaches people to grow theirown food. For more information aboutSoil for Life membership, and organicmethods for growing vegetables, herbsand fruit, please phone Pat on (021) 7944982Sheet mulching (or composting)is the simplest, and least labourintensive, method of building thefertility of most soil types andaffords the gardener an easier optionthan back-breaking spade workfor establishing a new garden. Itencourages the soil biota, many speciesof which will work the soil over for you -no digging required. It is a three-in-onemethod which combines composting,mulching and biodegradableweedkillers (cardboard and newspaper),and it enables you not only to improveyour soil but to grow and harvest a cropall at the same time.There are many ways of sheet mulching,two of which are discussed. Bothrequire enormous volumes of organicmatter initially and, thereafter, it becomesa routine activity in the gardento keep adding more mulching materialsto the surface as the soil floraand fauna break them down intolife-sustaining humus, and releasingnutrients which are gobbledup by the plants. The whole ideabehind it is to minimise soildisturbance.Here’s how to go about it:Method 1• Mark out the areas for yournew beds and, right on top ofwhatever is there (bare soil,weeds, grass), sprinkle somerock phosphate or bonemealand wood ash or dolomitic lime(for acid soils) or sulphur (for thosealkaline Cape Flats soils).• Cover the area with a layer of manureto provide the extra nitrogen to breakdown the dead leaves and roots of theplants that will be buried by the mulchingmaterials.• Then add alternating layers (6cm, or3 fingers, deep) of green, wet materials(lawn clippings, fresh leaves and prunings)and brown, dry materials (untreatedsawdust, autumn leaves, straw)and more manure, watering each layeras you go, until you have covered thedemarcated area to a depth of at least20cm. With vigorous Kikuyu grass it is agood idea to mulch the area up to 30 or40 cm deep. You’ll be surprised at howmuch organic matter it takes to do this.• Cover the whole area with overlappingsheets of newspaper (3 – 5 sheets) orcardboard (1- 3 sheets) to prevent weedseeds from germinating, and grass runnersfrom creeping through, and competingwith your plants. Wet the paperand cardboard thoroughly and, in a veryshort space of time, it will have rotteddown and disappeared, its job done.• Lastly, add a layer of compost, soil andmulch to hide the unsightly newspaperand, hey presto, you’re ready to plant.Make a hole in the mulch/soil layer, cuta cross through the paper or cardboard,add a dollop of good potting mix (halfcompost, half good garden soil) andplant your seed or transplant your seedling.Water well.Method 2• Mark out the areas for your new bedsand cover whatever is there (bare soil,weeds, grass) with between three tosix sheets of newspaper or one to threesheets of cardboard. Make sure thesheets are overlapping well and water.• Now proceed as above, layering green,wet and brown, dry materials and manureuntil the bed area is covered to adepth of at least 20 cm.• Add a layer of mulch to cover.• To plant up this sheet mulched area,simply make a hole in the mulch, add agood soil mix and plant.In both cases there is no need to useherbicides or other drastic measuresto kill the grass and other vegetation.The newspaper and cardboard will doit for you. A myriad different creatureswill take up residence in this bountifulenvironment, enriching the soil beneathwith valuable humus which willbe worked in by earthworms and otherorganisms which are, in effect, diggingthe soil for you.60 Biophile Issue 16