4. The soil is so compacted at the surface, that it is less frequented by _grubs_, etc., than when it is more loose.

5. When the soil is smoothed in this manner, there is less surface exposed for the evaporation of water with its cooling effect.

6. Light sandy lands, by being rolled in the fall, are rendered more compact, and the loosening effects of frequent freezing and thawing are avoided.

Although productive of these various effects, rolling should be adopted only with much care, and should never be applied to very heavy lands, except in dry weather when lumpy after plowing, as its tendency in such cases would be to render them still more difficult of cultivation. Soils in which air does not circulate freely, are not improved by rolling, as it presses the surface-particles still more closely together, and prevents the free admission of the atmosphere.

If well _under-drained_, a large majority of soils would doubtless be benefited by a judicious use of the roller.[AL]

MULCHING.

[What is mulching?

What are some of its benefits?]

_Mulching_ (called Gurneyism in England) consists in covering the soil with salt hay, litter, seaweed, leaves, spent tanbark, chips, or other refuse matter.

Every farmer must have noticed that, if a board or rail, or an old brush-heap be removed in spring from soil where gra.s.s is growing, the gra.s.s afterwards grows in those places much larger and better than in other parts of the field.

This improvement arises from various causes.

1. The evaporation of water from the soil is prevented during drought by the shade afforded by the mulch; and it is therefore kept in better condition, as to moisture and temperature, than when evaporation goes on more freely. This condition is well calculated to advance the chemical changes necessary to prepare the matters--both organic and mineral--in the soil for the use of plants.

2. By preventing evaporation, we partially protect the soil from losing ammonia resultant from decaying organic matter.

3. A heavy mulch breaks the force of rains, and prevents them from compacting the soil, as would be the result, were no such precaution taken.

4. Mulching protects the surface-soil from freezing as readily as when exposed, and thus keeps it longer open for the admission of air and moisture. When unprotected, the soil early becomes frozen; and all water falling, instead of entering as it should do, pa.s.ses off on the surface.

[Why does mulching take the place of artificial watering?

Why is the late sowing of oats beneficial?

From what arises the chief benefit of top dressing the soil with manure in autumn?]

5. The throwing out of winter grain is often prevented, because this is due to the freezing of the surface-soil.

6. Mulching prevents the growth of some weeds, because it removes from them the fostering heat of the sun.

Many of the best nursery-men keep the soil about the roots of young trees mulched continually. One of the chief arguments for this treatment is, that it prevents the removal of the moisture from the soil and the consequent loss of heat. Also that it keeps up a full supply of water for the uses of the roots, because it keeps the soil cool, and causes a deposit of dew.

7. It also prevents the "baking" of the soil, or the formation of a crust.

It is to be recommended in nearly all cases to sow oats very thinly over land intended for winter fallow after the removal of crops, as they will grow a little before being killed by the frost, when they will fall down, thus affording a very beneficial mulch to the soil.

When farmers spread manure on their fields in the fall to be plowed under in the spring, they benefit the land by the mulching more than by the addition of fertilizing matter, because they give it the protecting influence of the straw, etc., while they lose much of the ammonia of their manure by evaporation. The same mulching might be more cheaply done with leaves, or other refuse matter, and the ammonia of the manure made available by composting with absorbents.

[Why is snow particularly beneficial?]

It is an old and true saying that "snow is the poor man's manure." The reason why it is so beneficial is, chiefly, that it acts as a most excellent mulch. It contains no more ammonia than rain-water does; and, were it not for the fact that it protects the soil against loss of heat, and produces other benefits of mulching, it would have no more advantageous effect. The severity of winters at the North is partially compensated by the long duration of snow.

It is a well known fact that when there is but little snow in cold countries, wheat is very liable to be _winter killed_. The same protection is afforded by artificial mulching.

This treatment is peculiarly applicable to the cultivation of flowers, both in pots and in beds out of doors. It is almost indispensable to the profitable production of strawberries, and many other garden crops, such as asparagus, rhubarb, etc. Many say that the best treatment for trees is to put stones about their roots. This is simply _mulching_ them, and might be done more cheaply by the use of leaves, copying the action of nature in forests;[AM] for, unless these stones be removed in spring, they will sink and compact the soil in part during open weather.

WEEDING.

[What are some of the uses of weeds? Their disadvantages?]

If a farmer were asked--what is the use of _weeds_? he might make out quite a list of their benefits, among which might be some of the following:--

1. They shade tender plants, and in a measure serve as a mulch to the ground.

2. Some weeds, by their offensive odor, drive away many insects.

3. They may serve as a green crop to be plowed into the soil, and increase its organic matter.

4. _They make us stir the soil_, and thus increase its fertility.

Still, while thinking out these excuses for weeds, he would see other and more urgent reasons why they should not be allowed to grow.

1. They occupy the soil to the disadvantage of crops.

2. They exclude light and heat from cultivated plants, and thus interfere with their growth.

3. They take up mineral and other matters from the soil, and hold them during the growing season, thus depriving crops of their use.

It is not necessary to argue the injury done by weeds. Every farmer is well convinced that they should be destroyed, and the best means of accomplishing this are of the greatest importance.

[How may we protect ourselves against their increase?

Why is it especially important for this purpose to maintain the balance of the soil?]

In the first place, we should protect ourselves against their increase.

This may be done:--

By decomposing all manures in compost, whereby the seeds contained will be killed by the heat of fermentation; or, if one bushel of salt be mixed through each cord of compost (as before recommended), it will kill seeds as well as grubs,--

By hoeing, or, otherwise, destroying growing weeds before they mature their seeds, and

By keeping the soil in the best chemical condition.

This last point is one of much importance. It is well known that soils deficient in potash, will naturally produce one kind of plants, while soils deficient in phosphoric acid will produce plants of another species, etc. Many soils produce certain weeds which would not grow on them if they were made chemically perfect, as indicated by a.n.a.lysis. It is also believed that those weeds, which naturally grow on the most fertile soils, are the ones most easily destroyed. There are exceptions (of which the Thistle is one), but this is given as a general rule.

[How much salt may be used with advantage?

Why is the scuffle-hoe superior to the common hoe?]