FUNCTIONS of SOIL
- Physical support for plants [anchorage]; rooting environment; holds air, water & nutrients essential to plant growth; houses organisms necessary for making soil suitable to support plants
- Well-structured soil both holds water & allows it to drain.
It may become compacted & waterlogged if walked on when wet: this stops air from being available to plant roots & soil organisms & they die.
Mulch protects soil surface, keeps it warm & moist, keeps weeds down & nourishes soil life & plants; apply to moist [not frozen] soil whenever you can.
Garden compost, leaf mould & farm-yard manure, mushroom compost, spent hops, composted bark/wood chips/prunings, municipal green waste, hay/straw, & worm compost are all good sources of organic matter & can be applied as a mulch.
Plants need a variety of mineral elements for healthy growth & development; soil with plenty of organic matter [ or clay] holds onto these in a form easily absorbed by the plant; lighter soils [not clay-based] lose some nutrients through LEACHING by rain: Nitrogen & potassium [K] are most vulnerable & may need replacing. Seaweed is a good source of trace minerals.
Humus is the end result of decaying plant & animal matter, broken down by soil organisms: worms, insects, fungi & bacteria. It can hold 90% of its weight in H2O; it attracts & holds nutrients available to plants & prevents leaching. It binds mineral particles into crumbs, thus improving structure [pores > air, H2O]. It improves all soil types, & it encourages the presence of micro-organisms, worms etc.
Green manures: protect & feed soil, improve structure & provide habitat for predators; very good in winter [but too late to sow now], early spring & late summer when beds are empty.
Article By Ruth Urbanowicz