The objection made to the deep-working implements, like the plow, is that they injure the crop by cutting its feeding roots, and this has been found by careful experiment and observation to diminish the crop.

Some farmers object to using a light harrow for cultivation in the early stages of the crop because they say the harrow will destroy the crop as well as the weeds.  This danger is not so great as it seems.  The seeds of the crop are deeper in the soil than the seeds of the weeds which germinate and appear so quickly.  The soil has also been firmed about them.  Hence they have a firmer hold on the soil and but few of them are destroyed if the work is carefully done.

In working crops not only should weeds be destroyed but also surplus plants of the crop, as these have the same effect as weeds; namely, they occupy the soil and take plant food and moisture which if left to fewer plants would produce a larger harvest.

HILLING AND RIDGING

Except in low, wet ground, the practice of hilling or ridging up crops is now considered by those who have given the matter thorough study, to be unnecessary, flat and shallow culture being cheaper.  It saves more moisture, and for this reason, in the majority of cases, produces larger crops.

Sometimes during very long-continued periods of wet weather weeds and grass become firmly established among the plants of the crop.  Under such circumstances it is necessary to use on the cultivator teeth having long, narrow sweeps that will cut the weeds just beneath the surface of the soil.  Sometimes a broad-toothed tool is used that will throw sufficient soil over the large weeds near the rows to smother them.

The condition to be met and the effect of the operation should always be given serious thought.

We have considered after-cultivation as influencing soil fertility by checking a loss of water by evaporation and weed transpiration, and this is its main influence but other benefits follow.

Keeping the surface soil loose and open benefits fertility because it directly aids the absorption of rain, favors ventilation, and has a beneficial influence over soil temperature.  Indirectly through these factors it aids the work of the beneficial soil bacteria and the chemical changes in the process of preparing plant food for crop use.

CHAPTER XIX

FARM MANURES

FUNCTIONS OF MANURES AND FERTILIZERS

In Chapter II we learned that the roots of plants for their growth and development need a soil that is firm yet mellow, moist, warm, ventilated and supplied with plant food.  We also learned that of the plant foods there is often not enough available nitrogen, phosphoric acid, potash and lime for the needs of the growing plants.

Manures and fertilizers are applied to the soil for their beneficial effects on these necessary conditions for root growth and therefore to assist in maintaining soil fertility.