444 



*Hg. TROPICAL AGRfCtfLTURlST. 



[Jan. I, 1887. 



with the bottom spit should be spread over the ground. 

 For this purpose the refuse of the garden is excellent ; 

 if farm-yard manure be applied it should be in a 

 thoroughlj' decomposed state, for strong rank manures 

 of animal origin should never be applied for the 

 immediate crops of potatoes. Double-digging consists 

 in taking out a trench 3ft. wide and one spit deep ; 

 the manure is then raked from the surface of the 

 adjoining strip of the same width, and spread over 

 the bottom of the trench. A shovelful of hot lime 

 thrown ia with the manure will greatly aid its 

 decomposition and assist to eradicate vermin. The 

 bottom spit should then be dug up to a depth 

 of 12 in., well mixing the manure into the soil. The 

 top soil of the second or adjoining strip of 3ft. 

 should now be dug and thrown on to the just dug 

 bottom of the first trench, and so on until the plot 

 is finished. 



This method of cultivation of the potato is specially 

 suited to light sandy soils, which it the weather be 

 hot and dry, part with their moisture too freely, so 

 that the crop matures before the tubers have attained 

 their full size. The manure that is placed in the 

 bottom spit enters the rootlets downwards, for roots 

 do not strike downwards into the earth by the force 

 of specific gravity but by the power of nutritive 

 attraction, and all plants possess the natural instinct 

 of sending their roots in the direction that they can 

 find nourishmen*; most congenial to their wants. By 

 placing the manure deep in the soil the plant has 

 one uniform source of nourishment, and therefore 

 receives no check from variations in the weather, 

 during the growing season. 



Notwithstanding the animal and vegetable manure 

 placed iu the bottom spit, should the land be poor 

 and deficient in vegetable matter, a good dre.ssing 

 of well decomposed vegetable manure may be added. 

 Poor soils never produce a good crop, neither are the 

 potatoes of fitst-class quality, for vegetables, like the 

 flesh of animals, are always deficient in flavour if 

 they have been half starved. On stiff soils any 

 substance that serves to render them less adhesive 

 may be applied witii benefit; such as old mortar, 

 charcoal, burnt earth, ashes, lime, decayed leaves, &c. 

 They should be applied as early as circumstances 

 will admit and be well incorporated with the soil, 

 which should be allowed to remain as rough as 

 possible so that it may get the full benefit of frost, 

 Bun, and air. 



Different kinds of plants take up iu different pro- 

 portions the various inorganic constituents of which 

 they are composed. Thus we see the necessity for 

 applying the special inorganic or mineral manures 

 in proportion to the requirements of the plant. The 

 inorganic constituents of the potato tuber, as contained 

 in 1,000 lb. of its ashes are; — 



lb. 



Potash 557 



Soda 19 



Lime 20 



Magnesia 53 



Oxide of iron .. 5 



Phosphoric acid 126 



Sulphuric acid ,., .,, .,, ... 136 



Silica.,, .,, ,,, , 43 



Chlorine ,.. .,, , , 42 



1000 



Tbt! above aualysis shows the proportions that have 

 been abotracted from the soil by the plant while 

 growing, Potash, the principal alkali of land plants 

 largely predominates i hence the special value of wood 

 ashes as a manure for potatoes- Phosphoric acid is 

 Of animal origin, and is supplied to the soil in all 

 bone manures ; it is of special value jwheu applied 

 to cold wet soils, as it has a tendency to induce 

 early ripening of the tubers, Caustic lime enters 

 largely into the composition of the foliage cf the 



otato, and independent of its food-giving properties. 



t is of great benefit to the land by improving its 

 texture and dissolving veg:etable fibre. Common salt 

 Bhould be used only with great care as a manure 

 ''or potatoes: it ma^, however, lometimes be uKd 



? 



f 



with advantage on light dry soils, but it enters very 

 slightly into the composition of the plant. Green 

 crops ploughed under are a beneficial manure for 

 potatoes on both stiH' and sandy soils. They render 

 the clays less adhesive, and add to their productive- 

 ness by allowing the rootlets freer access in search 

 of food ; while in sandy soils they attract and retain 

 moisture. Artificial manures, when judiciously applie.\ 

 arc invaluable aids to the good culture of the potato, 

 as well as of other crops. One ton of potatoes con- 

 t:uns about 25 lb. of ash (which represents the inorganic 

 or mineral food of the plant); supposing an acre to 

 produce 10 tons of potatoes, there will be taken from 

 the soil by the tubers alone 250 lb. of matter per acre 

 in very nearly the following proportions — 



lb. 



Potash 141 



Soda 5 



Lime 5 



Magnesia 13 



Oxide of iron 1 



Phosphoric acid 31 



Sulphuric acid ... 34 



•Silica . ... 10 



Chlorine (salt) 10 



250 

 Some soils contain one or more of these consti- 

 tuents in abundance, so that it would be waste, and 

 in some cases injurious, to add more of that substance ; 

 yet, being deficient of some others, it is impossible 

 for the plant to arrive at perfection ; so special 

 artificial manures become a necessity for the success 

 of every crop that depends on the presence, in an 

 available form, of all the mineral constituents of 

 which the plant is composed. Stimulating manures 

 when applied to the potato in excess, are often in- 

 jurious, for by inducing a strong rank growth of 

 foliage the plant is rendered more susceptible to 

 disease, and the quality of the tuber is never so good 

 when stimulating manure has been applied to the 

 growing plant. — Queenslander, 



Packing Pears.— The French, who export more 

 Pears than any other nation, cover the inside of 

 the boxes with spongy paper or dry moss, which 

 absorbs the moisture. Each Pear is then wrapped 

 in soft paper, and placed in layers in the boxes, 

 the largest and least mature iu the bottom, filling 

 all interstices with the dry moss. Thus, they will 

 keep a month or more. They are so closely packed 

 that though they cannot touch each other, all motion 

 is prevented. If one decays the others are not 

 harmed. — Gardeners^ Chronicle. 



The Philosophy OF Vine Pruning.— The production 

 of graius of starch in the chlorophyll of the leaves 

 when exposed to the sun is a well-established fact. 

 This starch is subsequently dissolved, converted into 

 sugar and other substance fit for the food of plants, 

 and transmitted to the growing points or to the 

 store-places, where it is again converted into starch. 

 The production of starch in leaves is shown by 

 immersing the leaves in boiling water, to which a 

 little potash is added, and then plunging them for 

 a quarter of an hour in hot alcohol. The leaves are 

 by these means deprived of their green colour, and 

 the starch in them is now easily rendered visible by 

 the addition of tincture of iodine. By covering one* 

 half of the leaf with some opaque substance, leaving 

 the other half exposed to the sun, starch may bo 

 detected iu the uncovered half, while none is to bo 

 found iu that which has been shielded from the sun's 

 raj's. Signer Ouboui, who has made numerous ex* 

 periments on the Vine , says that this production of 

 starch increases gradually from the leaves at the base 

 of a young shoot to the middle and as gradually 

 diminishes from the middle towards the point, starch 

 being absent from the very young leaves near the 

 apex. These facts supply a reason for pruning, 

 for the young leaves above the flower bunches, not 

 producing starch, but on the contrary consuming it, 

 in so far deprive the berries of their s^g^r.—Gardencrt' 

 Chronicle. 



