288 



The Supplement to the Tropical Agriculturist 



points out that a means of discovering if the 

 stage of ripeness has been attained is provided 

 by shaking them. The water, which still 

 contain in small quantity, will cause a clear 

 sound which is very easily heard, and which dim- 

 inibhes in intensity on the commencement of 

 germination. Imperfectly ripened nuts, being 

 shaken, give only a dull sound, which little 

 experience 6ervesto distinguish from the former 

 one. Nuts, which have arrived at completematu- 

 rity while still on the tree, shouldalways be pre- 

 ferred to those which have been left to ripen in 

 the shade after having been cut. 



Some kinds of nuts, even when ripe, contain 

 a fair amount of water, and it is necessary to 

 dry them before sowing, for if they are put into 

 the earth immediately, there is a chance that 

 they will rot before they germinate. Drying 

 should be eouducted in the shade ; exposure to 

 the sun may produce a partial baking of the 

 kernel, which will interfere with germination. — 

 West Indies Agricultural Neios, Aug. 6. 



GREEN MANURING AND THE USE OF 

 COVER CROPS. 



When considering the all important subject of 

 Soil Management there is one point to which 

 planters often do not give sufficient weight, and 

 that is the damage and monetary loss caused by 

 wash. The top few inches of the soil are over 

 and over again the most important of all to the 

 crop. Endless time and money is spent in get- 

 ting a good tilth and making the surface soil of 

 such a mechanical condition that it will readily 

 absorb moisture on the one hand and retain it on 

 the other. This top soil when in good condition 

 ii the home of myriads of bacteria which render 

 the fertilising constituents available to the plant 

 and to it is added manures. Consequently every 

 effort should be made to retain every particle of 

 it if possible. A large number of corps are more 

 or less surface feeders, and if they are permanent 

 like Coffee, Tea, Rubber, Cocoa, &c, it is es- 

 pecially important that the surface soil should 

 not be removed. The heavy rains experienced 

 in the Tropics, often as much as 40 inches 

 in a single month, if they fall on bare 

 land carry away enormous quantities of top soil 

 into the drains and rivers, and the rich alluvial 

 plains of countries like India have been formed 

 by years of wash from the hills above them. 

 Where estates are kept clean weeded and the soil 

 left bare and exposed, the rivers and streams in 

 the wet weather are choked with fine silt being 

 carried away, silt which represents the tilth so 

 carefully obtainod during the year, and it is no 

 uncommon sight on such ostato3 to see the roots 

 of tho Tea or Rubber, as the case may be, stic- 

 king up several inches above the level of the 

 ground, showing where tho old surface used to 

 be and the loss which has been sustained. On 

 all sides it is agreed that this is wrong estate 

 practice, and all kinds of devices, such as tren- 

 ches, and pits, to catch the soil, are resorted 

 to in order to prevent the wash. The simplest 

 method of preventing surface wash is to grow a 

 cover crop to break the force of the tropic rain 

 and hold the soil together with their roots. The 

 beneficial effects of such cover crops in control- 

 ling the loss of surface soil by wash is admirably 

 shown by the following series of experiments 



conducted in Ceylon at the Peradeniya Experi- 

 ment Station, on average sloping land. The 

 rainfall during the year was 59*03 inches : — 



Plot treatment 



Bare weeded 

 Dadap (Krytlirina) 

 Deep forked 

 Albizzia 

 Ipomuea 



Crotalaria ineana across slope 



Wash in ton 

 of soil from 

 April 19C9 to 

 March 1910 

 per acre' 

 .. 115 

 ... 106 

 79 

 67 

 45 



m 



Mixed Crotalaria and Iudigofera, 1 foot 



apart, up slope .. 26J 



Crotalaria across slope, 1 foot apart, in the 



rows .. 26j 



Dosmodiuiu ... 121 



In addition to preventing wash and the loss 

 of valuable soil, cover crops, if they consist of 

 Leguminous plants, have anothor beneficial 

 effect. They add Nitrogen to the soil year by 

 year, the most expensive of all plant foods to 

 buy. This they abstract from the air through 

 the medium of bacteria in the nodules on their 

 roois a phenomenon too well known now a days 

 to need any description. Soils which have 

 been under natural vegetation for many years are 

 always found to be rich in Nitrogen, and this 

 Nitrogen has been taken from the air and accu- 

 mulated in the soil largely by the action of tho 

 Leguminous plants in the flora. It is sometimes 

 objected that cover crops rob the primary crop 

 of plant food, but this removal of food is only 

 temporary, as the cover crops are never removed 

 from the soil, but are from time to time cut down 

 and dug in or allowed to rot on tho surface, so 

 that thei r constituents are restored to the soil, 

 and in such a condition they become rapidly 

 availablejto plants. The best plan is to apply dres- 

 sings of Potash and Phospates to the soil and 

 then grow a leguminous covercrop on it to supply 

 the Nitrogen. The most suitable plant to grow 

 depends upon local conditions; the flora of any 

 estate if carefully examined will be found to 

 contain many leguminous weeds, and it is 

 both cheaper and easier to establish one of 

 these than a plant introduced from another 

 country or district which is very likely uusuited 

 to the local conditions, or may be attacked by 

 a local pest. The ideal cover plant is a non- 

 climber which makes a thick cover and does 

 not grow to a height of more than about 

 two feet; a rapid grower persisting in the dry 

 weather ; not attacked by disease to which the 

 permanent crop may be susceptible or by 

 diseases of its own. Many plants can be found 

 which comply with these demands fairly well, 

 and such should be used. The starting point is 

 a clean weeded estate. There can be no half-way 

 house between cover crops and clean weeding. 

 The weeds should be removed and destroyed as 

 soon as possible after the clearing is made, and 

 it is essential that certain plants which are 

 known to be harmful should be eliminated, and 

 then the cover crop should be established and 

 cultivated : it is no longer a ' weed ' but a desir- 

 able plant grown for a specific purpose. Coyer 

 crops thus established aid the conservation of 

 the soil, add Nitrogen and Humus to it and at 

 the same time reduce the weeding bill to a 

 minimum, an item of estate expenses which is 

 usually a very heavy one in the Tropics.— 

 Rudolph D. Anstead, Planting Expert. -Plan- 

 ters' Chronicle, Sept. 10. 



