For June, 1921 



615 



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A Lesson on the Plant In Relation To the Soil | 



Being One of a Series of Lessons of a Home Study Course on Gardening, Appearing Regularly in The Gardeners' Chronicle 1 



Under the Direction of ARTHUR SMITH I 



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While most people recognize the delinitioh of soil, the word is 

 sometimes used outside its true meaning and is applied to any 

 portion of the surface of the earth which is not hard rock. In 

 its real sense a soil is only that portion of the earth's crust in 

 which plants inay grow, and it is always composed of inineral, 

 animal and vegetable matter. The foundation of a soil is pul- 

 verized and disintegrated rock, which is purely dead inorganic 

 matter, incapable of supporting any of the higher forms of plant 

 !tfe, however finely it maj' have been disintc.gratcd. 



To become a soil this decomposed rock must have organic 

 matter incorporated with it, and, speaking generally, the greater 

 the amount of organic matter the greater is the fertility of the 

 soil, presuming that all other things are equal. Low forms of 

 plant life, like liciiens and mosses, are the earliest to start into 

 growth as they require practically no organic matter, and they 

 themselves are not only capable of dissolving rock but their 

 decay commences the production of organic matter and therefore 

 they mark the tirst step in soil foriuation. 



The characters of the original rock necessarily af^fect the physi- 

 cal and chemical properties of the resulting soil, as the various 

 rocks are composed of minerals having a different combination 

 of elements and a different percentage composition. These chem- 

 ical and physical properties together determine the value of a soil 

 for crop production. 



From the point of view of the plant — thai is of the higher forms 

 of plant life — a suitable soil for it is one which combines those 

 physical and chemical properties which are best suited to its 

 growth. 



There are many factors involved in the physical properties of 

 soils, but they are all ])ased upon the size, form, and arrange- 

 ment of the soil particles. Soils vary in weight with the com- 

 position and the size of the particles, and the size of these par- 

 ticles varies from those scarcely distinguishable with the micro- 

 scope, as with clay, to coarser rock fragments, such variations 

 determine the type of the soil, whether it is clay, sand, or loam. 

 In most soils there is a predominencc of one grade, as clay in 

 clay soils, and medium sand in sandy soils ; no soil is, however, 

 composed entirely of one grade. Clay particles are exceeding 

 small, it w-ould take live thousand of the larger ones, if laid in 

 a line with ed.ges touching, to measure an inch ; while it would 

 only take fifty of the medium sand particles to measure an inch. 

 Clay soils owe their properties to the fineness of the division of 

 their particles rather than to their chemical composition. Any 

 mineral when finely pulverized has physical properties similar 

 to clay ; but while this is true from a physical standpoint, the 

 term clay is chemically onlv applicable to aluminum silicate which 

 is formed only from the disintegration and decomposition of 

 feldspathic rock. It is this latter fact which causes clay soils to 

 be invariably richer than those known as sandy. The drawback 

 to a clay soil is its heaviness in working and the difficulties which 

 exist in handling it. Much of the trouble connected w-ith grow- 

 ing plants in a clay soil is due to improper cultivation, mainly 

 that of working it when too wet and sticky. From all points of 

 view the most satisfactory soil is that which is termed a loam 

 in which the properties of both sandy and clay soils are cotn- 

 bined in such a way as to eliminate the disadvantages of either. 



To a considerable extent the natural characteristics of a soil 

 may be gathered from the plants native to it. To give a few 

 examples: the Pin Oak is always found in a rich, wet soil, while 

 the Post Oak (Quercu.t stclhia) never grows naturally but in 

 soils which are dry. The prevalence of the Elm invariably indi- 

 cates a good .=oil with the water-table not very close to the 

 surface. Extensive woods of Piniis virgiiiiaiia show the ex- 

 istence of a poor, dry soil, as in the Pine barrens of western 

 Xew Icrsev. ' Black ,-\sh thrives upon swampy, undrained soils, 

 but White Ash flourishes best in fertile, moist, but at the same 

 time, naturally well-drained ground. The presence ot much 

 Sorrel (Rumcx ncctosa) whether in cultivated or uncultivated 

 soil is a sure indication of acidity, indicating that an application 

 of lime is required ; while the opposite condition— although of 

 course not absolute akalinity — is shown by plenty of Clover 

 growing. Horsetails (F.tiuisctuiii. si'.) as readily indicate that 

 subsoil drainage is required. .A plentiful and strong grow-th of 

 Chickwecd (Sti-Ilarh mcdui) is a pretty good sign of a fertile 

 soil, rich in humus. 



Most of our food crops have their special likes and dislikes 

 as regards soil. We know -that in many parts of the country 

 extensive districts are devoted to the commercial production of 

 some particular pl.tiit because the soil conditions are the most 

 favorable to it, while the district may be as distinctly unfavorable 

 for another. For example, it would be only courting failure to 

 attempt the growing of first class cauliflowers upon a soil emi- 

 nently suited to sweet potatoes, as the latter require a dry sandy 

 soil while the former do best in one of an almost opposite char- 

 acter. Although the physical properties of a soil are mainly 

 responsible for a given crop doing specially well in a certain 

 iocality, there arc sometimes climatic conditions which also have 

 a bearing upon the matter. 



While the coinmercial grower generally finds it necessary to fit 

 the crop to his soil, the home gardener has no choice in the 

 matter, as he has to grow something of everything his climate is 

 capable of bringing to maturity, irrespective of his soil, he there- 

 fore has to fit the soil to the crop. 



In a garden which has been well handled for a number of years 

 much of the soil's natural character will have become changed, 

 any extreme features it may have possessed ameliorated, and it 

 should have become fitted to grow any kind of garden crop satis- 

 factorily. In the case of a neglected garden or of a new one, 

 the first step is to plan the reducing of, and ultimately eliminat- 

 ing, any bad features it may possess. This is never the work 

 of a day, nor of a year, for in most cases it will take several years 

 of continual suitable treatment to bring a soil into such a condi- 

 tion that it will suit all the plants desired to be grow^n in it ; this 

 refers especially to the vegetable portion of a garden. 



On the ornamental side there are some plants that require spe- 

 cial soil relations which are easily supplied at once so far as 

 the initial planting in a suitable soil environment is concerned. 

 Among these the Rhododendrons and most other members of the 

 Ericacccc family are very particular in requiring an acid soil, 

 or at least one that does not contain any appreciable amount of 

 lime.* If it is determined to grow these plants and have them 

 permanently successful in a district having a soil naturally un- 

 suited to them, then at least two feet of the existing soil should 

 be reiTioved and replaced by that of a suitable character con- 

 taining plenty of humus and which shows an acid reaction when 

 tested with litmus paper. Again if we have a very poor and 

 extremely sandy soil and wish to grow roses two feet of the 

 sand should be removed and replaced w-ith a clayey loam. It is 

 ahvays possible to make the soil environment more pleasing to 

 anv plant of a permanent nature we wish to grow^ by adding 

 sufficient of some suitable earth at planting time to afford room 

 for at least a year or two's growth of roots, beyond which the 

 soil may be ameliorated to suit further root extension by cultiva- 

 tion and manuring, as well as by soil addition if necessary. 



While, in dealing with soils which have at some time or another 

 been under ordinary cultivation for any appreciable period, we 

 shall find them suitable for the general run of shrubs, etc., used 

 for ornamental planting, provided the preparation and setting out 

 has been properly done, in dealing with any extrcmeor peculiar 

 soil condition, tliere is luuch to be said in favor of fitting the 

 plant to the soil, as it is simpler and less expensive, -especially 

 as plants can be found which will fit any of the natural ixjsitions 

 capable of growing a plant at all, or in other words, there is a 

 plant for every place. In these days when people are rightly 

 giving more attention to American plants it is easy to have those 

 naturallv at home in any peculiar or extreme soil conditions our 

 lumie surroundings may afford, from a sandy bank to a swamp. 

 Too freipientlv plants are placed in soil for which they arc to- 

 tally unfited. "Mistakes in this direction are vcr\^ often made by 

 those responsible for the planting iilans. as many landscapists 

 pppcar to be vcrv ignorant of horticulture. There is considerable 

 to be learned from a knowledge of a plant's native habitat, not 

 cirly as regards soil conditions most suitable but also, in many 

 instances the best treatment to be given after planting. Take for 

 example Rhododendrons, wdiich we refer to again because it is 

 extremely rare to see a group of these doing really well in home 

 surroundings, and many who should grow- them refrain from 



• A few species of Rhododendrons have been discovered in China by 

 l-orcst and Wilson whicli apparently revel in a limestone soil. 



