Humus

“ The soil on which this thrives is a dark-brown vegetable humus, the débris of ages of rotting leaves and fallen branches, a very forcing-bed of vegetable life, which, constantly fed with moisture, illustrates in an astonishing degree the prolific power of the warm, moist shades of the tropics. ”

“ HOW HUMUS AND THE SUBSOIL ARE MINGLED. The mingling of humus and the subsoil is brought about by several means. The roots of plants penetrate the waste, and when they die leave their decaying substance to fertilize it. Leaves and stems falling on the surface are turned under by several agents. Earthworms and other animals whose home is in the waste drag them into their burrows either for food or to line their nests. ”

“ Nature turns all the excrement to humus, and humus is acknowledged to be the very best purifier of offensive nitrogenous matter which the world affords. The dark humus which is found everywhere, and which provides for all our needs, is nothing but excrement which has suffered a natural transformation brought about by a process which is purely biological. ”

“ Untouched by human hands, on the prairies and in the forests, topsoil is deepened year by year as winter frosts break up soft rocks, as dead grasses, leaves, twigs break down into humus, to become part of the topsoil and provide the nourishment for a new round of vegetation. ”

“ On examining the table it becomes manifest, that as far as its mechanical properties are concerned, humus is a substance of the very highest importance, for it confers on the soil, in a high degree, the power of absorbing and retaining water, diminishes its tenacity and permits its being more easily worked, adds to its hygrometric power and property of absorbing oxygen from the air, and finally, from its dark colour, causes the more rapid absorption of heat from the sun's rays. ”

“ Woods plants grow naturally in soil so rich in humus that it will hold many times its weight [215] in water. Season after season the trees drop leaves, needles, twigs, and branches that decay and maintain the high level of humus, which contains micro-organisms that help sustain the plants. In our area and in most other woodsy sections, forest soil is very acid. But the loam in a cleared area adjoining the forest may contain little or no humus, and may not be nearly acid enough for the native plants growing a hundred feet away. ”

“ Since the formation of the humus depends upon the decomposition of organic matter (mostly of the cellulose group) derived partly from the roots, partly from the leaves and stems of plants growing and dying on the soil, its accumulation near the surface is natural. But since the depth to which roots penetrate varies greatly not only with different plants, but very essentially in conformity with the greater or less penetrability of the soil and subsoil, the depth to which the dark humus tint may reach vertically varies correspondingly, from two or three inches to several feet. ”

“ The surface of a forest, in its natural condition, can never pour forth such deluges of water as flow from cultivated soil. Humus, or vegetable mould, is capable of absorbing almost twice its own weight of water. The soil in a forest of deciduous foliage is composed of humus, more or less unmixed, to the depth of several inches, sometimes even of feet, and this stratum is usually able to imbibe all the water possibly resulting from the snow which at any one time covers, or the rain which in any one shower falls upon it. ”

“ In a soil which is nearly all sand, or in one which is nearly all clay, few flowers will thrive, but in what is called a loamy soil—that is, one in which clay and sand are nearly equal—nearly all plants will grow and prosper if other conditions be favourable. The presence of humus in the soil is important in many ways, for not only does it contain much that is essential food for plant growth, but also it assists the earth in retaining that moisture without which life is impossible. ”

“ Where a thin sheet of humus, fertilized by lemmings, has accumulated, a few flowering plants appear, but even so their brilliant flowers spring direct from the soil, concealing the developed leaflets, while their horizontally spread roots grow out of proportion ”

“ Does it throw any light upon the new manure for which he is said to be taking out a patent? You speak of humus and humic acid. What do you understand by humus? as, according to Liebig, humus sometimes means one thing and sometimes another, and he appears to treat it very much as modern chemists treat phlogiston, as something which they don't comprehend, but which they need to explain the phenomena of vegetation. If you are a believer in humus, what is it composed of, and how does it act in forwarding vegetation? I suppose you will reply, By combining with oxygen and forming humic acid. ”

“ Lands that, on the one hand, are very hard and solid, with a tendency to bake, and, on the other, that are loose and leachy, are very greatly benefited by the addition of organic matter. When this organic matter—as animal and plant remains—decays and becomes thoroughly incorporated with the soil, it forms what is called humus. The addition of this humus makes the land mellow, friable, retentive of moisture, and promotes the general chemical activities of the soil. It also puts the soil in the best physical condition for the comfort and well-being of the plants. ”

“ Probably without realizing it, many non-gardeners have already scuffed up that thin layer of nearly pure humus forming naturally on the forest floor where leaves and needles contact the soil. Most Americans would be repelled by many of the substances that decompose into humus. But, fastidious as we tend to be, most would not be offended to barehandedly cradle a scoop of humus, raise it to the nose, and take an enjoyable sniff. There seems to be something built into the most primary nature of humans that likes humus. ”

“ It is certain that humus does not have a single chemical structure, but is a very complex mixture of similar substances that vary according to the types of organic matter that decayed, and the environmental conditions and specific organisms that made the humus. ”

“ On the other hand, our daily experience affords innumerable examples of plants growing luxuriantly in soils and places where no humus exists. The sands of the sea-shore, and the most barren rocks, have their vegetation, and the red-hot ashes which are thrown out by active volcanoes are no sooner cool than a crop of plants springs up on them. ”

“ Any fresh excavation of cellar or cistern, or cut for road or railway, will show the characteristics of the humus layer. It may form only a gray film on the surface, or we may find it a layer a foot or more thick, dark, or even black, above, and growing gradually lighter in color as it passes by insensible gradations into the subsoil. In some way the decaying vegetable matter continually forming on the surface has become mingled with the material beneath it. ”

“ This world would not be habitable were it not for the humus with which its bare rocks are clothed. The humus is the living covering of the skeleton, and its formation has taken ages. The primitive bare rock which has been 'weathered' by the changing seasons gets clothed with a growth of lichen. ”

“ They drink it through their roots, you know.
Not only does humus help with the matter of food, but it holds moisture in the soil, and in some almost magic way makes other plant food into a form which the plant can use.
Of course, you wish to give your plants the best kind of food, and of course you will want humus.
But suppose you cannot readily get stable manure, or leaf mold from the woods, why then, you can make humus. Every day the very things you need to make humus may be going to waste.
To Make a Compost Heap
Save all the vegetable tops, leaves, grass, etc. ”

“ The soil conditions should imitate as closely as possible those seen in thrifty deciduous forest. The soil should contain an ample supply of humus, well worked into the ground, to secure the lightness and moisture-retaining property of forest soils. The best form of humus is probably leaf mold, but good results may be obtained by mulching in the autumn or early winter with leaves, straw, stable manure, or similar materials. ”

“ Test the temperature of each after watering and standing in the sun for an hour. Sand is warmer than clay, also the presence of humus raises the temperature. This item is important, since most seeds decay instead of sprouting if the temperature is below 45° Fahrenheit.
11. Enumerate the services rendered to the soil by humus.
12. In Experiment 10, let the corn grow for some time and determine whether the very rich humus is the best in the end. Sand and clay are almost altogether mineral; leaf-mould almost entirely organic; neither alone is good, but a mixture gives the best results. ”

“ The composition of the mound from surface down was as follows: thin layer of humus; then yellow clay and humus mixed, becoming more largely mixed with humus as it reached the level of the surrounding country, this layer being 2 feet 10 inches; then a thin, light colored layer one-half an inch to an inch in thickness, which I suppose to be ashes of grass and leaves, as there was no sign of charcoal in any part of the layer; then a layer of a few inches thickness, similar to the surrounding soil ”

“ Plants.—Our study of humus shows the value of vegetable matter in soil. Besides contributing to the soil, plants break up rocks with their roots and dissolve them with acid excretions. It is interesting to study how a bare rock becomes covered with soil. ”

“ It has been already stated, that the humus contained in the soil consists of the remains of decayed plants, and there is every reason to suppose that the primeval soil contained no organic matters, and that the first generation of plants must have derived the whole of their nitrogen from, the atmosphere. ”

“ Most of our farm land consists of these four soils mixed in various proportions, and it gets its name from the one that preponderates. Thus we have our sandy, gravelly, or clay loams. Humus is likely to be present in all fields, because vegetable matter grows, to some extent, everywhere; but freshly broken land, reclaimed swamps, and prairie lands are likely to be especially well supplied. The great value of humus in the soil will appear in later studies. ”

“ Humus, which, it has been pointed out, is decaying vegetable matter, serves as a sponge for the absorption of soil water and for underground water supplies. Therefore, the more humus that can be plowed into the soil, other conditions being equal, the greater is the ability of the plants growing in that soil to withstand drouth. As soils are cultivated, the tendency is for the humus to become “burned out” and to have a reduced moisture-holding capacity. To overcome this tendency, it is necessary to add vegetable matter to the soil whenever it is possible. ”

“ The decaying vegetation which we find mixed with the soil has other uses. It holds water and so helps to keep the soil moist. It makes the soil loose and more easy to cultivate. It absorbs heat from the sun and so helps to warm the soil. This vegetable matter, when it is completely decayed, we call humus. Soils that are rich in humus are usually very fertile. ”

“ On this account I ventured some years ago to speak of the humus as the 'Living Earth,' and I take it that no more important addition has ever been made to the stock of human knowledge than the recognition that the humus teems with life, and that its fertility and healthiness depend entirely upon biological processes. ”

“ Undoubtedly the most effective of these is the natural forest with its soil, composed of porous humus, covered by a blanket of decaying leaves, branches, and fallen trees, and often with a dense mat of underbrush growing among the trees. ”

“ Soils with about the same content of humus show variations in the power to absorb aqueous vapors which are almost proportional to the amount of clay which they contain. With the increase of humus substance, the power of the soil for absorbing moisture is increased, so that a sandy soil which is rich in humus often will retain as much moisture in an air-dried state as a clay soil which is poor in humus. If the experiment is carried on by drying over sulfuric acid instead of at 100°, the sample should be left from four to seven days in order that a constant weight may be reached. ”

“ The leaves, flowers and fruits, augmented by certain plants which grow in the shade of the trees, form a layer of mould, or humus, which protects the soil against rapid changes of temperature, and greatly influences the movement of water in it. (3) The roots of the trees penetrate into the soil in all directions, and bind it together. ”

“ Organic matter that has been in soil for a while has been altered into a much studied substance, humus. We know for example that humus always has a carbon to nitrogen ratio of from 10:1 to about 12:1, just like compost from Garden "B." Garden writers call great compost like this, "stable humus," because it is slow to decompose. Its presence in soil steadily feeds a healthy ecology of microorganisms important to plant health, and whose activity accelerates release of plant nutrients from undecomposed rock particles. ”

“ Two principles, both important as relating to soil texture, now have been illustrated. Soils must not be worked when they are so wet that their particles will cohere, and organic matter, or humus, must be kept mixed with the mineral matter of the soil. In practical farm operations, if the soil can be made into a mud ball it is said to be too wet to work. The required amount of humus is retained in the soil by occasionally plowing under some green crop, as clover, or by applying barn manures.
Fig. 35. The glass of water at the right has received lime and the clay has been flocculated ”