View allAll Photos Tagged Humus,
The day concludes with a visit to working certified organic Vegetable farm, Good Humus Produce. A small unique family farm, owned and run by Jeff and Annie Main since 1976. Jeff provided a tour and discussed the how nature takes control, so he doesn’t have use pesticides or chemicals, and how the Capay Valley community that eats the food supports the farm.
FOREST SOILS
SOIL HORIZONS
The soil is not a chaotic mixture, nor does it change gradually from surface to parent rock. Instead, several layers or horizons are evident in a mature soil.
Two horizons comprise the top soil. The A horizon is uppermost. Organic matter from the humus, the layer of decomposed leaves which rests upon the soil, is mixed into the A horizon by soil organisms. As rain water percolates through this horizon it dissolves soluble salts. Organic and carbonic acids contained in the water react with mineral compounds to replace potassium, aluminum, iron, and other basic ions. The water also washes clay, silt, and organic colloids downward, which leaves the horizon coarser in texture.
The B horizon is enriched with materials washed from the A horizon. Clay, silt, and colloidal humus lodge in pore spaces and impart a compact structure to the horizon. Iron and aluminum compounds often give the horizon a yellowish or rusty color.
The subsoil or C horizon consists of partially-altered bedrock. It is usually below the depth to which humus materials penetrate.
The soil is a continually varying mixture of weathered mineral particles and organic matter. The properties of a soil depend upon the weathering processes which have affected it, the nature of the parent rock, its topographic position, and the vegetational cover.
The forest relies upon the soil for water, mineral nutrients, and support. In turn, the forest molds the soil by modifying climatic conditions, accumulating various inorganic compounds and producing complex organic compounds which ultimately enter the soil, and through disturbances caused by roots and burrowing animals.
PODZOL
Podzols form in regions with cool, humid climates. They are
characterized by a strongly-bleached A horizon.
Long winters and the impoverished condition of the A horizon inhibit organisms which decompose organic matter and mix it with the soil. Therefore, most podzols are covered with a thick organic layer which is distinct from the mineral soil.
The forests which grow on podzols often are composed of spruces, firs, larches, northern pines, white birch, and aspen.
A red spruce (Picea rubens) is exhibited here.
The bunchberry (Cornus canadensis), and Clintonia (Clintonia borealis), shown here, are herbaceous plants which often grow in podzols.
GRAY-BROWN PODZOLIC
Gray-brown podzolic soils occur in regions with humid, temperate climates. They are rather uniform chemically and their horizons are seldom marked by distinct color changes.
An active soil population causes rapid decomposition of organic matter and mixes it with the mineral soil. Consequently, there is no sharp boundary between the humus layer and the mineral soil.
Forests in the eastern gray-brown podzolic region are composed principally of oaks, hickories, sugar maple, and beech. A shagbark hickory (Carya ovata) is exhibited here.
Common trees in the western region are douglas fir, western cedar, western hemlock, western white pine, and sitka spruce.
The spring beauty (Claytonia virginica) and jack-in-the-pulpit (Arisaema atrorubens), shown here, are typical spring-flowering plants of the eastern gray-brown podzolic soils.
RED-YELLOW PODZOLIC
Red-yellow podzolic soils are found in regions with warm, humid climates. In well-drained, upland sites, reddish colored soils are characteristic. In poorly-drained sites, where oxidation of iron compounds is incomplete, yellowish colored soils are typical.
The long warm season is very favorable to organisms which decompose organic matter. Their work is so rapid and thorough that little organic matter remains to be incorporated into the mineral soil.
The forests which occur on red-yellow podzolic soils are composed chiefly of southern pines, oaks, and hickories. A longleaf pine (Pinus palustris) is exhibited here.
Various grasses, including the pineland three awn (Aristida stricta) and the slender bluestem (Andropogon tener), shown here, are commonly found on red-yellow podzolic soils.
The roots of a tree are essential organs. They absorb water and minerals from the soil near their tips, transport food materials, provide space for food storage, and afford firm anchorage for the aerial portions of the tree.
There are two general forms of tree root systems: the tap and fibrous root types. A tap root system consists of a main, vertical root, supplemented by a loose network of smaller, lateral roots. In some species, the tap root of a large tree may extend to a depth of 12 or 15 feet. Many species of oaks, hickories, and pines have tap root systems.
Fibrous root systems are composed of numerous horizontal roots bearing a dense network of smaller rootlets. These roots are concentrated in the upper levels of the soil and in the humus layer. The beech, the various maples, spruces, firs, and larches are among the many fibrous rooted trees.
These diagrams represent the root systems of two of the exhibited trees, the long leaf pine (tap rooted) and the red spruce (fibrous rooted). Notice that the spread of the tree crown is not a reliable index of the spread of its roots.