Organic Matter Flashcards
(21 cards)
What is soil organic matter?
A mixture of plant and animal remains, excreta and living organisms added to the soil by natural means(eg:leaf litter) or by the action of humans (eg:spreading farmyard manure)
What is the organic layer?
The top layer of the soil which is rich in OM and this layer can be absent, thick or thin
What is the benefit of humus on topsoil?
The humus makes the topsoil highly porous allowing it to hold air and moisture for seed germination and root growth
What are the benefits of soil OM?
As OM is decomposed by soil organisms, mineral ions are released into the soil and are available for uptake by plant roots. Improves soil structure and organic soil health. Plants grow well
What are the different types of organic matter?
Peat, coir, spent mushroom compost, garden compost, leaf litter, grass clippings, wood chips, bark chips and Cocoa shells
What are the benefits of mulches?
Conserves/retains moisture, suppresses weeds, may improve structure, regulates soil temperature and protects soil surface and reduces erosion
What are the different types of mulch?
Wood chips, chipped bark, leaf litter, leaf mould, grass clippings, chopped straw, farmyard manure, spent mushroom compost, green waste, garden compost, Cocoa shells, pebbles, gravel, shells and recycled glass
What is a soil ameliorant?
A substance that improves the physical condition of the soil
What are the benefits of humus?
It Coats the soil particles and modifies their characteristics. It is important on sandy and silty soils as it forms stable crumbs. It can combine with clays to make them less sticky. It’s important in soil aggregation. It improves the water holding capacity. It can hold onto cations and prevent leaching
What are soil organisms needed for?
Breaking up the complex substances in decaying plants and animals so they can be used again by living plant.
What is cation exchange capacity?
Clay and humus particles have negative electrical charges or ions on the surface so they can hold on to positive cations such as calcium. The negative charges and nutrients such as calcium can help bind parti les together improving the structures
What is mycorrhiza fungi?
Fungus living intimately with the roots of a plant to a mutual advantage
What are the issues with adding OM to soil?
Nitrogen lock up, toxicity, weed seeds, diseases, plant scorch, environmental damage, pH change, contaminants and ring barking
What is nitrogen lock up?
If the proportion of carbon in the OM source is higher than 25:1 the bacteria will remove soil nitrogen to address the difference. The nitrogen will be later released when the bacteria die. To overcome nitrogen lock up rot OM before adding it to the soil
How does adding OM lead to toxicity?
Some wastes are high in certain heavy metals. Eg: paper pulp and aluminium
How does adding OM cause weed seeds?
Weed seeds are common in garden compost and manures and are usually killed by heat over time
How does adding OM lead to diseases?
Not uncommon to find important diseases such as honey fungus present in wood chip and bark
Why is OM important to the soil?
Provides a valuable source of plant nutrients. Is able to hold and retain nutrients against leaching. Improves the structure of the soil. Increases water retention in sandy soils. Improves the soil structure and aeration in clay soils by opening up the pore spaces between soil particles. Is a food source for soil organisms. Darkens soil which aids heat retention and gives earlier warming in spring
