From the garden ELLEN PEFFLEY
In last week’s column were instructions on constructing a compost bin from pallets. In today’s column we talk about what to add to the new compost bin.
Why compost? Compost is a free source of organic matter that is used to amend garden soils. Organic matter in the soil is a simple, effective, even critical management tool in improving soils.
Organic matter adds these benefits to soils:
• Sandy soils with the largest particles are least fertile, drain water quickly, and leach minerals. Organic matter increases water and mineral retention.
• Clay soils with smallest particles are difficult to manage. Water penetration is slow; soils become rock-hard if allowed to dry. Organic matter loosens and makes soils more crumbly, which aids water absorption.
All organic matter is mostly carbon (C) molecules combined with lesser amounts of nitrogen (N). It is the balance of these two that is critical when amending a soil. The key to a successful compost is getting the right amounts of each, the carbon-to-nitrogen (C:N ratio).
The most effective amendments have a low carbon-tonitrogen ratio, C:N. The optimum C:N ratio added to a soil is 20:1, 20 parts carbon to one part nitrogen. Most organic matter begins with a higher C:N ratio. As microorganism begin the decomposition activity the C:N ratio lowers.
Some common sources of raw organic matter and their C:N ratios: Wood chips 400:1 Shredded cardboard 350:1 Sawdust 325:1 Shredded newspaper 175:1 Pine needles 80:1 Leaves fruit waste 60:1 Hay 25:1 Coffee grounds 20:1 Kitchen waste 20:1 Grass clippings 20:1 Manures 15:1 All the above may be composted but the higher the carbon number, the longer the decomposition time.
Begin with a layer of clippings, add a little soil – important because this is the source of the microorganisms, a little water and repeat the layering. Toss the pile every week or so to aerate the pile, which hastens the decomposition.
What should not be composted are animal products like meat, bones, dairy, grease, animal waste, or any clippings that have been treated with herbicide.
Some information from modernfarmer.com Ellen Peffley Harp, a retired professor of horticulture at Texas Tech University, writes about gardening for several Texas newspapers.
