March, 1909.] 



278 



Scien liflc A gricu I lure. 



Sulphur and phosphorus are both 

 taken from the soil by plants. Both 

 substances are found in tbe form of 

 calcium salts. Sulphur is found largely 

 in the form of gypsum. Phosphorus is 

 found in most soils iu combination with 

 iron. Plants deficient in phosphorus 

 assume a red appearance. 



Potassium is essential to all plant life 

 in the formation of carbobydrat.es such 

 as starcb, sugar, and cellulose. If potas- 

 sium is absent from tbe soil the growth 

 of plants stops and the leaves refuse to 

 continue their functions, that is the for- 

 mation of starch within tbe chlorophyll 

 grains (green colouring matter). 



Magnesium enters a plant in the form 

 of sulphates and phosphates as also does 

 calcium to which it is closely allied. 

 Magnesium is said to work with nitro- 

 gen in the formation of chlorophyll and 

 protoplasm, 



Iron is widely distributed in soils, and 

 is also necessary for the formation of 

 chlorophyll of plants. 



All combinations of lime that are 

 necessary for plant nutrition have their 

 origin in calcium vvhich is chiefly of use 

 in strengthening the fabric of the plant. 

 Besides this it is valuable in fixing 

 oxalic acid, which although produced 

 by most plants is poisonous to them. 



The subsidiary nutritive substances 

 such as sodium and silicium also play 

 their important parts in the growth of 

 plants. Sodium is taken up by most 

 plants in the form of common salt which 

 in itself has considerable manurial value 

 when applied to soils for certain crops. 



Silicium is always present in soil as 

 silicia, and like lime is used to strengthen 

 the cell walls. 



Other substances of this class are occa- 

 sionally present in plants, but are not 

 sufficiently Simportant to require men- 

 tion in detail here. 



The question of how to replase those 

 nutritive substances which are ab- 

 stracted from the soil during the growth 

 of plants is an important one to the 

 agriculturist, and embraces the all-im- 

 portant subject of manuring. Green 

 manuring has already been touched on, 

 other manures are generally divided into 

 three kinds, vis. (a) Stable or Farm-yard 

 manure, (b) inorganic manures, (c) organic 

 manures. 



Stable manure contains all the food 

 substances of plants, and when available 

 is the best means of replacing those sub- 

 tances which have been exhausted from 

 the soil during the growth of the crop. 

 In this country it is not obtainable in 

 sufficient quantities, unfortunately, to 

 35 



supply anything like the demand, but 

 when possible it should be used in pre- 

 ference to all others. 



Bones for field crops or fruit trees are 

 extensively used as manure. The fertiliz- 

 ing qualities are lasting when the bones 

 are used in a crushed state and more 

 active when in the form of powder. 

 Bones contain large quantities of phos- 

 phoric acid which is a valuable fertilizer. 

 Bone meal has for many years been suc- 

 cessfully used on sugar and coconuts, and 

 is recommended as a splendid manure 

 for all estates. It can be shipped direct 

 from home (which is advisable) or obtain- 

 ed in Penaug or Calcutta. 



Guano is a well-known and valuable 

 manure, being the excrement of birds. 

 Many of the limestone caves in Perak 

 and Selangor contain deposits of bat- 

 guano which can generally be collected 

 on payment of a small fee- It is a quick 

 acting and very powerful manure. Its 

 beneficial effect on green crops and 

 grass land is rapid and very marked. Up 

 to the present time T have not heard of 

 it having been used on rubber or coconut 

 plantations, but I feel sure that if suffi- 

 cient quantities can be obtained it will 

 be a valuable manure for these purposes. 



Leaf mould is invaluable as a manure 

 either as a mulch round the roots of rub- 

 ber 1 and coconut trees or when dug into 

 stiff soils. Large quantities of leaves 

 are obtainable on every estate, and these 

 when thoroughly decayed form a cheap 

 and most effective manure. 



Many artificial inorganic manures are 

 now in favour. It is true they do not, 

 like stable manure, contain all the food 

 substances required by plants, but they 

 contain the most important ones in a 

 more concentrated form. The strength 

 of artificial manures and their adap- 

 tability for certain crops is determined 

 by their analysis which all respectable 

 dealers supply with their goods. All 

 substances entering into plant food must 

 be in a state of fluidity or in the form of 

 gas or air, therefore the chief recom- 

 mendation of an artificial inorganic 

 manure should be its power of yielding 

 as much soluble matter as possible to tbe 

 roots, and that in a gradual manure. 



Ammonia is one of the chief component 

 parts of all manures and has a powerful 

 stimulati ng action on tbe growth of 

 plants. It is supplied in inorganic man- 

 ures chiefly in the form of ammoniacal 

 salts. 



Potassium appears in commerce in the 

 form of potassium sulphate. It tbe soil 

 is not rich in lime it is advisable when 

 manming with raw potassium sulphate 

 to add a considerable quantity of quick 

 lime, 



