Manures and Fertilizers
A garden is always made on ground that has previously been cultivated, and so the soil is assumed to be sufficiently fertile for vegetable production. But vegetables take a lot out of the soil. Many are greedy feeders; the vegetation is nearly all taken away instead of being allowed to die down and decay into the ground, and the soil is not enriched, as it pasture, by animal droppings. So the gardener must constantly feed the soil with animal manure and fertilizers for good results.
Plants need a considerable number of chemical substances with which to build up their stems, leaves, flowers, and fruits, but from the practical gardener’s point of view only for need to be considered. The other substances are usually present in the soil, and certainly in all soil reasonably well worked and well supplied with decaying organic manure.
Apart from this organic matter, or ‘humus’, which is dealt with below, the four substances of vital importance are:
Nitrogen: This makes plants grow to a large size, increasing the length of the stems, the size of the leaves, flowers and fruits. Without nitrogen, the plants are stunted and the foliage may become prematurely yellow.
Potash: A general stimulant, increases in depth of color of leaves and flowers, and maintaining health.
Phosphorus: This encourages the growth of flowers and fruits.
Lime: This acts on soil particles in such a way that plant food is made soluble and roots can absorb it.
One might think that if these four chemical substances are essentials, the Gardner need only apply them generously to be quite sure of good crops in the garden. Soil fertility is hardly so simple an affair as that. It is, in fact, so complicated that scientists are still trying to solve its mysteries, and the more they explore them the more complex the subject appears. However, the practical gardener will not go for wrong if he keeps more or less to these four fertilizers, provided he understands how they should b balanced one against the other.
The first consideration when dealing with the question of fertilizers is the texture of the soil. This must be got right before anything else is done. If soil has not enough decaying organic matter in its composition to take hold of, and hold on to, the plant foods, it is just a waste to use fertilizers.
Plants can absorb only soluble food. The reason why they do not grow in desert sand is that water passes down through the soil into the subsoil so rapidly that the plant roots have no time to take in plant food that is in the solution. If your garden is too sandy, you can keep on forever giving it soluble fertilizer and still have poor crops.
By burying grass, weeds or manure, you add humus to the soil, and it is this humus which holds on the moisture even during drought. You have only to turn over a deep pile of leaves in the height of summer to know how moisture is held by them. Other vegetable matter -- decaying plant crops, and so on -- are similar in this respect to leaves, and so are the various farm and stable manures. It is up to every cultivator, therefore, to turn his attention to provision of humus and best way for average householder to accumulate stores of this valuable material is for him to make a compost heap.
It is not absolutely necessary for vegetation to be decomposed before it is dug into the soil, but experiments have shown that the most value is added to the land when partly decomposed organic refuse is incorporated. There is an old saying that "the proper place for manure to decay is in soil." This would seem to contradict the statement that manure should be partially decayed before it is used in the ground.
The true meaning of the phrase is that manure should not be allowed to lie uncovered on the soil surface or even in a heap. If stable manure is stacked temporarily in a heap, it should always be covered with a layer of soil 3 in. or 4 in. thick, which will absorb the ammonia that the manure gives off. As it is the ammonia of the manure heap that makes it offensive, the soil covering will be appreciated by neighbors! Mulches of old decayed manure are sometimes recommended. The manure used for these should be in dry crumbly condition, not wet and odorous. If manure is in warm, moist condition, and is used to mulch soil surfaces, it should be turned in under about 3 in. of soil.
In the average garden, large enough to supply the bulk of the produce needed by the household, the supply of available refuse from the house (where a lawn exists) and from the sweeping up of the leaves is quite sufficient to form enough compost to meet needs of the vegetable plot. This does not mean that food sufficient for the needs of the plants grown has been supplied, but only the sufficient organic matter or humus is in this way put back into the soil. Plant food is also necessary.
Generally speaking, the chief value of manure is its power to hold plant food in solution. The best place for it, therefore, is where plant roots are likely to be; that is, in or just below the top fertile soil. As small seedlings and a good many older plants are damaged if their roots come into actual contact with fresh manure, the best practice is to fork manure lightly into the trenches dug when preparing the ground for the crop.
Although the contents of the compost pit are not very rich in actual food, animal droppings, which contain other waste products, do actually feed the plants, for they contain all the three vital plant foods -- nitrates, phosphates, and potash.
Very rarely, however, are the quantities of stable manure available sufficient to supply all the plant food that the crops need. The best way to supplement the supply is to use a dressing of a general fertilizer that contains all three foods. A good one is made up from following:
- 7 lb sulphate of ammonia (a form of nitrate)
- 14 lb of sulphte of potash (a form of potash)
- 28 lb of super phosphate of lime (a form of phosphate)
Though we speak of super phosphate of lime, this does not mean that there is any free lime in the chemical: as a matter of fact, there is no available lime in it at all, and lime has to be added to the plot after digging, weather a general fertilizer is used or not, when the soil needs it.
The three ingredients, the proportions of which can vary a little according to the plants that are being treated, can be mixed freely and stored ready for use as and when required. The mixture recommended can be used at the rate o 1-2 oz per sq yd among growing crops, or over soil that is to be forked over in summer or autumn to receive a fresh crop. Not all common fertilizers are suitable for mixing. Nitrate of soda, for instance, is a useful form of nitrogenous fertilizer, but it must be applied by itself and only during the growing season. Do not try to mix it.
There are, in addition to general fertilizers, various other substances commonly used by gardeners. Each has a definite position in horticultural practice. Some are best on light soils, some are heavy, some best for autumn use, some for spring. Some are impure and to be used with extreme caution, some are concentrated and suitable for use in very small quantities on very special plants.
It is to make these points clear that these fertilizers are described below, but first it must be emphasized that, if you dig well, use organic matter as manure in the trenches, and supplement this with a general fertilizer, you can grow most crops very well indeed, and it is not worthwhile to do anything more than this on a small plot. There are many artificial fertilizers, but those listed are the most profitable in average garden.
Sulphate of ammonia: Suitable for use on all soils except acid ones. Can be used in spring and summer at the rate of ½ oz per sq yd. Should not be mixed with basic slag or lime, but can be mixed with sand for even distribution. Use as top dressing.
Nitrate of soda: Suitable for soils, but especially valuable applied to light soil frequently during active growth. Use in liquid form, or water in well applying top dressing of about ½ oz per sq yd.
Calcium cyanamide: Suitable for lime free soils. Apply to vacant ground only, at least seven days before it is sown or planted, at ½ oz per sq yd if used in conjunction with organic refuse.
Nitro-chalk: Useful on heavy or acid soils at 2 oz per sq yd in spring and summer. Mix into the surface layer while digging or hoeing.
Soot: Of slight food value only; its chief value lies in its power to raise the soil temperature by darkening its color. Sprinkle until soil surface is black. Also useful, with lime, as an insecticide.
Dried blood: A good spring dressing for any soil at ½ -1 oz per sq. yd.
Superphosphate of lime: It should be regarded as an acid manure, and where the soil is naturally acid, superphosphate should be used in spring only after heavy winter dressings of lime. An average dressing is 2 oz.
Basic slag: A valuable form of phosphate for the vegetable garden. Suitable for all soils, so long as they contain humus. Slow acting; therefore lasting in effect. Use in autumn or winter 2-4 oz per sq yd.
Bonemeal or boneflour: Up to 3 oz per sq. yd is a good dressing suitable for soils that are not too well supplied with humus. Can be applied in spring but is slow acting and its effect is felt over the second season.
Dissolved bones: Use as boneflour. Best for use on chalky soil.
Points to Remember
- Never mix fertilizers unless you are quite sure that they will mix satisfactorily. Some will make unwelcome chemical changes if they are mixed before use.
- Always apply artificial fertilizers sparingly. Crush all large lumps before you begin, divide up the fertilizer into small quantities each sufficient for a given strip of land, scatter thinly and evenly with a sweep of the hand.
- Never allow fertilizers, whether applied dry of watered on the watering can, to go on to plant foliage. If they do, wash them off immediately with clean water.
- Never apply liquid fertilizer to very dry soils. Always use the hose or watering can first.
- Never use fertilizers on small seedlings that have not yet taken hold of the ground, or on sickly plants. It is like overfeeding babies and invalids!
Suphate of potash: Very useful on heavy soils mixed up to 1 oz per sq yd with other fertilizers in spring or autumn.
Kainit: Less pure than sulphate of potash but equally useful except on a few crops such as strawberries, where the purer form is needed. Can be used at 2 oz per sq yd in autumn.
Nitrate of potash: For all soils in spring or autumn at ½-1 oz per sq yd.
Lime/Slaked lime: Any quantity up to ¾ lb per sq yd can be used, but 4 oz the first season and an annual dressing of 2 oz to 3 oz is about right for the average plot. Dress over the surface after digging. There is a belief that lime and manure should not be used together. Actually, lime hastens decay. The manure is dug in, and the lime added as a surface dressing.
Powdered chalk: Use exactly as lime, but more freely, on light soils.
Gas lime: To be used only on vacant soils in autumn, where land can lie idle until the spring. It is an insecticide and very useful on soils where club root has been troublesome. Use at about 4 oz per sq yd.
A compost heap, valuable as a source of fertilizer in any garden, is built up of garden refuse that will quickly decay; hedge clipping, glass cuttings, leaves, plants tops, weeds, faded flowers, cabbage leaves, pea and potato haulms, and any kind of vegetable refuse from the kitchen. Diseased growth should, however, nor dead bushes or prunings.
When each layer becomes about 6 in. thick it should be well trodden down and sprinkled with animal manure, a little calcium cyanamide, sulphate of ammonia (1 oz per sq yd), or proprietary compost maker.Sprinkle frequently with watering can as the heap is built; the material will not decay properly if it is too dry. A thin layer of soil should be spread over each layer of refuse, also a little garden lime if animal manure is used.
While the heap is decomposing, it should be turned over occasionally to admit air and so hasten decomposition. The compost may be ready in two months, depending upon conditions.