DRY FARMING.

New Zealand Journal of Agriculture, Volume XXII, Issue 1, 20 January 1921, Page 19

DRY FARMING.

R. McGillivray,

Fields Instructor, Christchurch.

The fundamental principles of what is termed “ dry farming ” or “ dry culture ” concern the storage in the soil of the annual rainfall, its retention there until required, the prevention of direct evaporation, the choice of plants suitable to , arid conditions, and the sowing of -resisting strains. Dry farming may be further defined as the intensive cultivation of the soil in country of scanty rainfall to conserve moisture. It is not farming without moisture, but. saving and making the utmost use of what rain does fall. Aridity is a condition met with in parts of almost" all countries ; dry farming is therefore a world-wide problem. Its objects are the profitable production of useful crops without irrigation on lands which receive a rainfall of, say, less than 20 in. per annum, but its methods may be profitably employed where the rainfall is much in excess of that mentioned. In dry regions the conservation of natural moisture for crop-production is of paramount importance, as under such circumstances water is the limiting factor. In Australia there are immense areas that can only be brought under production by dry farming, while in the United States of America there is estimated to be over 1,000,000 square miles, or about ten times the size of New Zealand, that cannot be irrigated, and so must be reclaimed by dry culture. Extensive tracts of country of a similar nature are to be found in Africa, Asia, South America, and also in Europe. More than one-half of the land surface of the globe receives a rainfall of less than 20 in. per annum, and about one-quarter 10 in. or less per annum. It has been estimated that a perfected system of irrigation could affect only about one-tenth of these vast areas, and the reclamation of the remaining nine-tenths could not be done except by dry farming. Where irrigation is impossible dry farming is thus the only key to the settlement of dry country, and as such should receive the cordial support of all those interested in closer settlement. If conditions are suitable and the work is systematically performed, ■ dry culture cannot fail, for the practice is based on thorough tillagethe supreme principle of successful agriculture.

Although there is good evidence that the ancients practised the art of dry culture in various parts of the Old World, it is only in comparatively recent times that the modern agriculturist has given attention to the work. The celebrated agriculturist, Jethro Tull, born in 1674, was the pioneer British dry-farmer. His methods of soil-tillage lie at the foundation of the modern system of dry culture. The honour of having brought prominently to the front the present dry-farm agriculture of the Western World belongs to the people of Utah. In 1847 the pioneers entered Great Salt Lake Valley, and inquiring minds set to work to find out how to grow crops without irrigation. Experiments proved that the project was a feasible one, and from that time on the practice has grown and prospered.

DRY-CULTURE METHODS.

The soil mulch and its management is perhaps the most important point in dry farming. By a “ soil mulch ”is meant a loose layer of soil of varying depth on the surface of the field, produced by means of cultivation for the purpose of breaking capillary action and so preventing the escape of moisture. The mulch should be renewed as often as required, and its renewal is imperative after every fall of rain. The dry-farmer must beware of weeds. They have no place in dry culture. They are moisture-thieves, and a weedy dry farm, irrespective of soil or situation, is doomed to failure. The fertility of the "'"soil must be maintained by the application of farmyard manure and litter, or the occasional ploughing-under of a leguminous crop. In a soil of high fertility, plants will attain maturity with a minimum supply of water.

Sowing the seed is an operation that in point of importance is comparable to efficient ploughing and the maintenance of the soil mulch. Broadcasting of seed is quite foreign to the principles of dry farming. The. dry-farmer must have control of his soil, and must place the seed at a sufficient depth to enable it to come in contact with moisture.- All seed must be sown through the seed-drill, and it must be borne in mind that the amount of seed required in dry culture is about one-half of that required under humid conditions of agriculture. Wheat has from earliest times been the staple crop in arid regions, but oats, rye, and barley are all now grown successfully. Lucerne has proved its worth under dry culture, and potatoes are now known to respond well, and under such conditions are of high quality.

The quantity of water required by plants in dry regions is about one-half more than in humid climates, and the dry-farmer should ascertain the average annual rainfall over the area he intends to farm. Meteorological records are of importance to all farmers, but to the dryfarmer their importance is enhanced. He should also be closely acquainted with his soil and subsoil, so as to know. exactly what treatment to adopt to conserve the precious moisture. Deep sandy loams or silty soils well supplied with organic matter are the best for dry-farming practice. Investigations in Utah proved that under a good system of culture it was possible to conserve 95 per cent, of the total precipitation for plant-use. Deep ploughing and the thorough pulverization of the soil, to be followed by rolling and then cultivating

to form a surface-soil mulch, are factors which if attended to will enable suitable soil -to hold the maximum amount of moisture. The depth of the mulch is important. Investigations have shown that cultivation to form a soil mulch 4 in. deep reduced evaporation by 72 per cent., cultivation 8 in. deep reduced it by 88 per cent., while a mulch 10 in. deep almost wholly stayed the loss of moisture. The watchword of the dry-farmer should be “ Cultivation.” The ■development of dry culture is teaching the old but too-often-forgotten lesson of the value of good tillage and the cultivation of growing crops.

SOME NEW ZEALAND EXPERIENCE IN DRY FARMING.

Extensive areas in New Zealand could be profitably farmed under dry-culture methods. Our rainfall varies from about n in. in parts of Central Otago up to about 120 in. in some other parts of the Dominion. A considerable portion of the South Island ranges within the 20-30 in. rainfall, and where soil conditions are at all favourable dry culture would render crop-failures under such a rainfall an impossibility. Dry farming is only in its infancy in the Dominion, but examples of its successful practice may be cited.

Considerable interest has been aroused by the dry farming carried on at the Terrace Orchard Company's property, of some 800 acres, at Alexandra by the manager, Mr. G. H. Barker. As already indicated, Central Otago has a climate of exceptional dryness, while the summer temperature is high. The average number of days per annum on which rain falls .may be set down as about sixty. The rainfall for the twelve months ended 31st December last amounted to only about 12 in. Yet on the Terrace property, under such circumstances, remarkable results have been obtained, despite the fact that the land is not eminently adapted for dry culture. The accompanying photographs indicate the evolution of a part of the property from the extremity of depletion to a condition enabling the production of a crop of oats returning 2 tons of chaff per acre. Last season an acre of wheat on this property yielded .60 bushels, and onions gave a most profitable return. Fruit-trees are also flourishing. The experience at the Terrace Orchard is similar to that of many others in like country namely, the absolute necessity for early and deep ploughing, good cultivation, rolling, and the formation of the soil mulch to the requisite depth so as to save the winter moisture for summer crop-production.

Dry-culture methods were tried last season on the farm of Mr. H. S. McCully, of Waitohi, near Pleasant Point, South Canterbury. A field of approximately 50 acres was sown in rape on 15th November, and manured with rape-fertilizer at the rate of 1 cwt. per acre. Portion of the field was worked under dry methods, being intercultivated by Mr. McCully for the purpose of conserving moisture, allowing aeration of the soil, and destroying weeds. The value of this method was apparent from the earliest stages of the experiment, and at the end of the season was exemplified to a wonderful degree. The plants of rape growing on the dry-culture area were giants in comparison with those on the -remainder of the field. The root-system of the former was vigorous, and the plants were not checked in growth during dry spells, as were those growing on the remainder of the field. The advantages of dry farming as shown in this experiment are of outstanding importance.

It I has been estimated that the dry-culture area gave a yield of fodder at least 400 per cent, in excess of the portion grown under ordinary farm practice: The field was inspected by Mr. J. T. Smart, Director of the Technical School, Temuka, and he has certified that the experiment and result were as stated. From the photograph here reproduced it .'will be seen that the estimated increase is quite a conservative estimate. From an inspection of some of the plants by the writer he is of opinion that 600 per cent, would be quite within the mark.

Under dry-farming methods production could thus be enormously increased. On many farms even with a marked decrease of area under crop the results under a system of dry culture would be much greater than at present. The soil conditions would be improved, and each succeeding crop would derive substantial benefit from the intercultivation of the preceding one.