Vol. VIII. Xo. 185. 



THE AGRICULTUKAL NEWS. 



1(55 



WATER IN THE SOIL. 



The important beariiiff \thieh the supply of 

 moisture in the soil exercises upon the fertility of the 

 land has naturally been the cause <>f much investigation, 

 which has had for its object to ascertain the movements 

 that water undergoes in the soil, how the moisture is 

 retained, the relative proportions of water held by 

 different kinds of soils, and the methods of cultivation 

 which are best adapted to economise and utilise to the 

 best advantage the small supply' of moisture which 

 results from a low rainfall. A great amount of knowl- 

 edge has now been placed on record in regard to these 

 points, the application of which is proving most valuable 

 to the practical agriculturist. The following notes in 

 this connexion are taken from an article which appeared 

 in the Phili pjiinc A(/rkulfural Revicir for June 

 last : — 



The water that plants use is that which remains in the 

 soil alter drainage, and is held in the form of a tihn of 

 moisture around lach partic-Je.of eartli. 



Good agricultural soils hold capillary water equal to ^ 

 about 30 per cent, of their weight. Plants are not able to 

 use this water after it has dried out to about 12 (ler cent., so 

 that when the soil is in the best condition for plant growth, 

 only about 60 jier cent, of the total moisture is available to 

 the plant. During the dry season loss of water takes place 

 by evaporation at the surface of the ground as well as through 

 the leaves of the plant. Fortunately for the roots of the 

 plant, this water tends to maintain an even balance ; that is 

 to say, when a portion of the soil dries out, this water moves 

 toward the diy place from the point of greatest moisture. 

 An example of tliis is when the surface dries, and water from 

 below conies up to take the place of that lost by evaporation. 

 AVhen water has been taken out of the soil by the roots of 

 plants, other water moves towards this spot, and, of course, 

 carries with it soluble plant food, jnovided there is any in 

 the .soil. 



The rapidity of movement of capillary water depends 

 upon the size of the soil particles and the proportion of fine 

 and coarse particles. Water will move more rapidly through 

 coarse sand than through clay, but as the water is held in 

 the soil in the form of a thin tilm around the soil grains — and 

 thei'e being more surface of the soil grains in a cubic foot of 

 tine clay than in the same i|uantity of sand — theie will be 

 more water moved in the clay soil in a given time than in 

 the sand, although the water moves more slowly in the clay 

 than in the sand. Hence clay soils do not sutt'er from 

 drought as much as sand}' .soils. 



Most agricultural soils, when composed of the proper 

 mixture of sand and clay, have a tendency, under normal 

 •conditions, to form small clu-sters of soil particle.-^, ju.st as 

 .small particles of sand tend to cling to larger ones, thus 

 bringing about the best mechanical condition. This mechani- 

 cal condition is destroyed when the soil is stirred wliile wet. 

 This is called 'puddling.' Soil so handled, when exposed to 

 the direct rays. of the sun, becomes very hard. This condi- 

 tion is known as 'bakiiVg,' and simply means that the 

 granular structure has been destroj'ed, and the soil particles 

 ■cemented together by drying. Soils allowed to bake in this 

 manner are very difficult to put in good condition again. 

 The mechanical condition may be improved by the use of 

 shade crops, such as velvet beans, etc. The shade allows the 

 slow action of capillary water to restore this cluster condition. 

 Working when the land is in proper condition will also tend 

 to improve the soil. 



A controlling factor in soils, so far as moisture is 



concerned, is hunms. Humus is partially decayed leaves, 

 grass roots, or other organic matter in soils, which on account 

 of the great nund>er of cells, has a high water-holding 

 capacity. The pretence ol humus makes the soil dark or 

 black in colour, so that in most countries a dark soil is 

 regarded as a rich soil, but such is not always the case. 



All soils in tropical climates are more or less devoid of 

 humus unless they have been recently cleared of their virgin 

 forest, or are formed of the washings from surrounding 

 hills. The main cause of this absence of humus, however, 

 is the fact that deeompo.sition goes on constantly, and the 

 excessive rainfall w^ashes out the soluble matter. 



The pie.sence of humus not only adds fertility to the 

 soil, but makes it more porous and open, thus increasing the 

 water-holding capacity, which is an important factor during 

 the dry season. 



The character of the sub.soil has considerable infiuence 

 on the amount of moisture that will be available for the use 

 of plants. As mentioned above, the supply of capillary 

 moisture is the governing factor in plant growth. Also only 

 a limited amount of moisture is held in the soil, hence the 

 storehouse below the surface must be large, so that the 

 capillary water may be drawn up from 6 or 8 feet below the 

 surface. A thin layer of soil underlaid with gravel will 

 suffer much from drought, while, on the other hand, a deep 

 layer of clay insures a good supply of moisture during the 

 dry season, but provides poor drainage in the rainy .season, 

 when good drainage is essential except for rice and few grass 

 crops. 



DOMINICA AGRICULTURAL AND 

 COMMERCIAL SOCIETY. 



A meeting of the Dominica Agricultural and Commercial 

 Society, at which a variety of matters were dealt with, was 

 held at lioseau on March 20 last. 



It was announced that a satisfactory arrangement had 

 been entered into with the Royal Mail Company relative to 

 retaining the coasting steamer ' Yare ' at Dominica. A con- 

 tract for five years had been made, in virtue of which the 

 Covernment were to pay the Royal Mail Company £2,000 

 a year for three years, and £1,500 for the balance ot the 

 period, and the Company was to have the option of with- 

 drawing the steamer at the end of three years. 



The President said that the Secretary of the West India 

 Committee had been good enough to make full enquiries in 

 London concerning the jjacking of oranges for shiimient, and 

 had reported as follows : ' I have made enquiries at Covent 

 Garden, and from the information which I have obtained, 

 have no hesitation in saying that the standard Florida box 

 is by far the most suitable package for Washington navel 

 and other fine varieties of oranges. It was pointed out to 

 me by one dealer that if it is too costly to import these boxes, 

 or the material for their maaufacture, it would be desirable 

 to imitate them from local woods, or imported woods, as 

 closely as po.ssible. On the other hand, one important firm 

 told me that it would pay shippers to import the American 

 boxes, as the liuyers take the packing very much into account. 

 Given oranges of the same variety packed in slatted crates, 

 and standard Florida boxes, the fruit in the latter would 

 undoubtedly command the higher price. 



A communication from Martinique was brought forward 

 at the meeting, asking if seeds of the I'ara rubber tree 

 {Ifeneo /jnisitiensu) could be ]mrchased in Dominica. It 

 was pointed out that the trees now in the ir;land were not yet 

 mature enough to yield seed, and that planters in Martinique 

 must be recommended to obtain a supply from Ceylon 



