Although organic matter is important in soil, orchardists usually don’t think much about it.
They are too busy managing their crops and trees, controlling pests and diseases, irrigating, organising labour and doing other essential things, plus many orchardists think that supplying organic matter to soil is too costly.
Organic matter makes up only a small part of a soil (at best 5%), yet the organic matter packs a mighty punch in the orchard.
When the orchardist builds up organic matter in soil, he contributes more in the long-term to healthy soil and trees than does any other resource—far greater than the 2-5% of organic matter suggests! Here, we show why organic matter is important, what it is, where it comes from, and how the orchardist can build it up in soil.
Why is organic matter important in soil?
Organic matter in soil affects the growth and production of fruit trees chemically, biologically and physically, as follows.
- As a slow release fertiliser, organic matter directly and indirectly provides nutrients to the trees and cover crops
- Provides nutrients and energy for the many organisms (microorganisms, animals) in soil
- Helps to buffer soil against big swings in pH when chemicals are added to soil
- Improves structure and resilience of soil, and so affects the supply of water and air to roots and microorganisms
- The added organic residues also act as slow-release fertilisers so help to replace the many nutrients that are removed from the orchard in harvested fruit. The nutrients attached to the humus are not easily leached down to the ground water away from the roots. However, the orchardist still needs to add inorganic fertiliser to make up for nutrients removed at harvest.
What is soil organic matter and where does it come from?
Organic matter in soil ranges from fresh unchanged organic materials through to highly decomposed organic materials.
Continued next month
For more information, see Tree Fruit May2014
