Why compost

1
Why compost?
How to make it?
Mauricio Avila, PhD Soil Scientist, Kapalua
Farms, MLP mavila_at_mlpmaui.com 808 357 1792
Most organic materials are compostable. Food
wastes, yard trimmings, crop residues, animal
manures, many industrial wastes (lumber milling,
brewing, distilling, etc) There is need for an
adequate mix of high nitrogen (leaves, grass
clippings, fruit/grain residues) and high carbon
residues (branches, old grass, saw dust). The
ratio of Carbon to Nitrogen (CN) should be about
40. That mix also includes water and adequate
oxygen levels. Temperature must reach 120 to 150
F and stay there for about 2 weeks. Turning
should happen often (every 2 to 3 days) over that
period to enhance aeration and thus the
humification process. After temperature drops
below 100 F it can sit in place protected from
rain and age over time. Composting can take from
a 6 to 8 weeks (accelerated) to 8 months or more
(with an aging process).
Compost produces humified organic matter that
will stay longer in the soil. The humus
provides higher nutrient retention and water
retention, better soil structure, and higher
microbial activity. It also adds nutrients, N, P,
Ca, Mg, K. Composting also eliminates pathogens
and weed seeds from organic amendments.
2
Adding compost was equivalent to liming and
increased biomass production
General increases in nitrogen, organic carbon,
phosphorus, potassium, calcium and magnesium are
common pH correction has been critical for the
success of our crops and our cover
crops Although compost is not a large source of
N, better cycling improves N retention and
availability to crops over time.
Field 298
Field 8