376 



The Supplement to the Tropical Agriculturist 



Mr van der Poorten said he had no inten- 

 tion of planting rubber but Coconuts. Java 

 was the country for coconuts, although there 

 was at present only a beginning in planting 

 them up ; but the laud he had obtained was 

 just suited to the product — and in Java coconuts 

 came into bearing almost twice as quickly as 

 in (Jeylon, and gave larger yields. The results 

 were, in fact, better even than in the Malay 

 States. The other product he meant to plant- 

 he has a manager already in charge — was Cocoa, 

 his own specially selected Venezuelan variety, 

 of which he had supplied seed now to so many 

 Ceylon planters, one which never suffered from 

 canker and was, in fact, a powerful resistant of 

 disease. This he was convinced would grow 

 well and bear prolifically in the alluvial un- 

 dulating land he had secured. Close to it 

 there is another block of jungle of equal dimen- 

 sions which Mr van der Poorten will probably 

 secure in due course — this time direct from Go- 

 vernment, without paying the initial R25 per acre 

 to a concessionaire, thus reducing the total cost 

 of his (say) 7,500 acres to some P*12 - 50 per acre. 



TILLED AND UNTIL LED SOIL. 



The operation of tillage has, for its primary 

 object, the stirring and loosening of the soil. 

 When soil-particles are massed loosely, as in 

 a tilled field or garden, spaces exist between 

 them, and these spaces permit of free move- 

 ment of air. If the particles are packed together 

 tightly, as in pasture land where the soil cannot 

 be loosened, there is comparatively little space 

 between the particles, and consequently the 

 amount of air in the soil is but small. All grass 

 land, as compared with that under tillage, is 

 insufficiently aerated, and in most cases the 

 older the sod the less well ventilated it is ; for, 

 as time passes, the soil-particles become more 

 closely packed. The ideal soil may be compared 

 to a sponge, not only because of its capacity for 

 holding nutritive solutions, but because of its 

 permeability to air. There can be no question 

 that the high productiveness of well-cultivated 

 soils is due largely to the greater amount of air 

 available for the roots. 



The presence of air ensures Loth oxygen and 

 carbonic acid in the soil. Oxygen is essential to 

 the growth of well-being of the roots of plants, 

 no less than to the aerial parts. CarboDic acid 

 plays an important, though indirect, part in en- 

 suring soil fertility by bringing inorganic mate- 

 rials into solution and thus augmenting the sup- 

 ply of mineral food-substances. 



Beneficial micro-organisms are found in greater 

 numbers and are better distributed in a culti- 

 vated soil than incompact and uncultivated soils. 

 These lower forms of life, like the higher forms, 

 are profoundly affected, both astotheirindividual 

 well-being and as to their multiplication, by such 

 conditions as food, air, moisture and tempera- 

 ture, all of which factors are better regulated by 

 cultivation. 



One of the object of tillage is to convert the 

 soil into a suitable living place for micro-orga- 

 nisms through the increased humus, good drai- 

 nage, ventilation and higher temperature. It is 

 not unreasonable, therefore, to assume that the 

 greater number and better Condition of the micro- 

 organisms in a tilled orchard contributes to the 

 well-being of the fruit trees. 



There is evidence to show that all plants, to a 

 greater or less degree, so change the soil in which 

 they grow as to make it wholly or partially unfit 

 for the succeeding crop of the same kind. Diffe- 

 rent crops growing in the same soil may injure 

 each other, or the one the other. Two theories 

 are advanced to explain these antagonisms of 

 plants. One is that plants excrete toxins ; the 

 other is that the injurious eti'ect is the result of 

 bacterial activity. 



Mr. Spencer Pickering, of the Woburn Ex- 

 perimental Fruit Farm, in accounting for the in- 

 jurious effect of grass upon young Apple trees, 

 attributes the harm done neither to competition 

 between grass and tree for moisture and food, 

 nor to a difference in temperature. He holds that 

 it is due, not to excessive amounts of carbonic 

 acid, but to some "actively malignant effect on 

 the trees, some action on them akin to direct 

 poisoning. More recently, Mr. Pickering leaves 

 the question open as to whether the .harmful 

 action is the effect of a poison (toxin) excreted 

 by the roots of the grass, or whether it is the re- 

 sult of some change in the activity or composi- 

 tion of the micro-flora brought about by the 

 grass sod. Beside these specific experiments 

 with Apple trees and grass there have been re- 

 cently several investigations with other plants 

 to show that vegetable organisms have inter- 

 dependencesother than those with their physical 

 environment. For example, investigations with 

 Peach trees grown in pots with several plants 

 showthatthe Peachdoes not thrive if its rootsare 

 in close proximity to those of certain otherplants. 



The well-being of nearly all plants which mi- 

 nister to the needs of man is improved by til- 

 lage. Fruit trees not only respond to high culti- 

 vation in the nursery row, but they need good 

 treatment after transplantation to the orchard. 



In experi meuts to determine what are the com- 

 parative effects of tillage and grass sod on the 

 Apple tree, it is found that tillage is generally 

 better than sod, but it should not be expected, 

 however, that sod will be deleterious in the same 

 degree under all conditions. 



It is reasonable to suppose, for instance, that 

 ,in a deep soil, where the Apple tree roots can 

 escape from the grassroots, or in one containing 

 a great amount of soil moisture, the harmful 

 effeots of the grass will not be so marked as in 

 cases of an opposite nature. Investigations do 

 not show that the Apples cannot be grown in 

 sod. There are many orchards which prove the 

 contrary. It is suggested, however, the Apples 

 thrive in sod, not because of the sod, but in 

 spite of it. Tho proof that there are many thrifty 

 orchards in grass sod is not proof that these or- 

 chards would not do better under tillage. 



The statement is often made that trees will 

 become adapted to grass. There is nothing in 

 the experiments conducted in this country or in 

 the Colonies to indicate that such is the case. 

 Trees planted in sod begin to show ill-effects 

 even in the first year in which orchards are laid 

 down to grass, and each succeeding year but 

 adds to the injury. Trees can hardly be expected 

 to become adapted to thirst, starvation, asphyxi- 

 ation and poisonous excretions. 



J. J. Willis, Harpenden. 

 (The Gardeners' Chronicle, November 20, 1909. 

 p.,387.) 



