FERTILITY OF SOIL.

Sun (Christchurch), Volume I, Issue 121, 27 June 1914, Page 2

FERTILITY OF SOIL.

Mr G. S. de Baylis, Fields Instructor for- the North Island, read an interesting paper at the National Dairy Show last week, entitled " What Constitutes a Fertile Soil?" in which it was held that the whole science of agriculture is built upon the answer to the question, and it is also in that answer that every undertaking, every detail-performed in practical farming, finds the reason for its performance. An analogy was drawn between the-functions of the stomach in what it does for the human body, and the soil in fulfilling for the plants practically the same ' functions. This brought them to what constituted a fertile soil, and under three sections were given: (1) The necessity-of possessing raw materials to build up the framework and tissue of the plant—nitrogen, phosphoric acid, potash, Caleium, sodium, iron, Sulphur, silican and chlorisal, oxygen, carbon, hydrogen, magnesium, manganese; (2) all factors necessary to disintegrate the raw material and cause it, to rot; (3) a considerable extent of lime to neutralise the aeids often generated in the soil. The paper thpn went on to deal with the necessity of the soil to retain, a large amount of soil moisture. It was rarely found necessary to supply all the ingredients used by plants in the form of artificial manures, but there were four exceptions, nitrogen, phosphoric acid, and lime, and on many soils it was often found necessary to supply one or all of these if profitable crops were to be produced. Dealing with these four, their advantages to plant life was stressed. The paper went on to state that when the vast unoccupied gum lands of the far north were really brought into a productive state, it would be when the people realised that the first steps to bring these lands into profitable occupation were: (1) To discover all outcrops of fair quality lime convenient to lands; (2) establish small grinding plants thereon, owned and worked on the cooperative principle by settlers who need lime; (3) plough the land, put a fair dressing of lime upon it and fallow it for twelve months. The subject of humus, or vegetable matter in an advanced state of decay, was then touched upon/ it being stated that when the amount of humus in the soil declined the crops suffered by the short supply of phosphoric acid. Further, it acted a«-a sponge on the soil, soaked up moisture and therewith plant food, and held it, as it wtere, ready for the plant to draw

upon as it required it. This then brought up the question of rotation of crops—one of the. means made use of by farmers in the building up of soil fertility. It might be described as the science of utilising one crop to feed upon the residue left in the soil by its predecessors. The .advantages were briefly stated: (1) Poor quality lands ; we t re brought into profitable occupation; (2) soils did not become depleted of any particular ingredient; (3) no particular area was likely to become depleted of plant food; (4) tends, to clean the land; (5) distributes the work of the year and thus provides continuous work on the farm. The building up of secondclass land was then referred to. - The work of building up a soil was a slow one, and man should put Nature in the way of doing the work for him. Nature in her vast laboratory performed more work in a day tlian an army of men in a lifetime. Draining induced a healthy circulation of air, having rendered the soil sweet, ploughing and. cultivation exposed the soil to the disintegrating and mellowing influences of the atmosphere. Coming to a fertile soil, the conditions necessary were summarised as stated in the opening, and the paper went - on to deal with the mechanical condition of the soil as dealing with size, shape, composition and. relation of the soil particles on one another. The fertility of a soil from this view depended largely oir tlie power of soil to absorb water, retain water, permit of a healthy circulation of air, allow of a supply of subsoil water from the top for the use of the plant during periods of drought by capillary attraction. Instances in which mechanical fertility was notably lacking having been given, the pumice soils were' turned to. These soils lacked humus, and were low in the elements of plant food. Yet these could be rendered if proper methods were adopted, and it was doubted not that some serviceable country could in the course of time be built .up out-of the present apparently barren plains. The gum lands also were fully dealt with. The paper then dealt with the progress of New Zealand from an agricultural point of view. Having converted the forest into pastures, the farmer now had to turn on certain proportion of his pastures into arable -lands to grow food to top off his-sheep and provide supplementary food for tlie short period of drought; There was no doubt, continued the paper, the rapid progress of science had forced them I through an equally cycle of rapid changes as regarded agricultural methods. A farmermust now know; his soil, what is fertility, and the crops to grow, and th® various requirements of

j each. The methods of the future in the conversion of pastures into arable land j were advocated the same as in the past, ' complete the work as they went.' An entry of daily weather conditions was stated as an extremely valuable indicacesses of the crops grown. The paper concesses of the crops grown. The paper eluded by laying down the following principles:—(l) Crops of the same kind should never follow one another; (2) after a given term of years the land, wherever possible, should be laid down in pasture for a certain season; (3)~ all rotations should provide .that at some period "a leguminous crop should be grown; (4) J;he rotation practised should permit of the ploughing under of the residue of green crops as often as passible. Mixed farming and not the '' one irian business" was also advocated.