Vol. X. No. 23-5. 



THE AGRICULTURAL NEWS. 



141 



STUDENTS' CORNER. 



i\rAY. 



FiiisT Period. 

 Seasonal Notes. 



In lime cultivation, the work at the present time is chief- 

 ly concerned with care of the soil in the matters of weeding, 

 draining, forking and manuring; in the last connexion, the 

 preparation of the land is particularly imiwrtant where artifi- 

 cial manures are to be used. Give details of the way in 

 which this preparation is best carried out. The heavy rain- 

 fall received during the period that is just past will have been 

 useful in giving indications as to those parts where drainage 

 is required most urgently, and it may be necessary for this 

 work to be undertaken at an early date, in order to prevent 

 the loss of plants, following short periods of heavy rainfall 

 that may occur. Trees that are dying on account of the want 

 of drainage of the soil in which they stand often appear as if 

 they are being killed by root disease; the similar appearance in 

 the two sets of untoward circumstances is due to the fact that, 

 in both eases, there is interference with the efficiency of the 

 roots, so that like symptoms are produced. Dry weather, 

 during the next few months, will prevent much uev.^ work 

 from being done in the nursery. The chief matters for atten- 

 tion will be to assist the seedlings to resist the effects of lack 

 of rain and to keep the nursery beds free f lom weeds. How are 

 these matters accomplished, and why is the second of them 

 very iinportant? In very dry weather, the fungi parasitic on 

 scale insects usually become comparatively inactive; what 

 aid may be given in order to enable them to resist severe 

 drought? Compare the convenience of applying green dress- 

 ings and heavy mulches in lime orchards with that on cacao 

 estates, and state why this is less easily done in the former 

 instance. Where pen manure is being bedded, in lime cultiva- 

 tions, care must be taken to avoid injury to the roots, as this 

 naturally interferes with the development of the trees, and may 

 cau.se them to lean over heavily. All paia.sitic and epiphytic 

 plants should be removed from the trees, at the present time. 

 Returning to matters connected with the nursery, the receipt of 

 heavy showers may cause the loss of many seedlings through 

 fungus disease. What steps .should be taken to prevent this 

 as far as possible? Toward the end of the present quarter, the 

 lime crop will begin to mature, so that preparations will have 

 to be made for collecting the fruit. What , preliminaries are 

 often necessary in order to facilitate this colleetionf 



During the present season, much attention will have to 

 be given to the sanitation of cacao orchards." In pursuance 

 of this, dead branches will have to be removed, and all dead 

 wood cut out, the wounds that are left being dressed with 

 Bordeaux mixture, and after a few days, with tar. The 

 present time is most suitable for the application of special 

 manures and mulches, and as in the case of limes, the drain- 

 age of the soil should receive attention. May is a favourable 

 month for carrying out the grafting of cacao. Observations 

 should be made in order to ascertain where additional wind- 

 breaks, if any, are required, and the preliminary arrangements 

 for planting these should be carried out. 



In very dry regions, in some parts of the world, salts 

 cellect in the soil to such an extent as to render impossible 

 the growth of plant.s. Although these conditions do not exist 

 in the West Indies, the matter is of importance, as it indicates 

 -the way in which the content of soluble salts in the soil is 



influenced. The fact that certain soluble salts are necessary 

 to living plants does not preclude the possibility, under given 

 conditions, of the quantity of such salts becoming so great as 

 tointerfere seriously with their growth, or even" to prevent 

 this from taking place. In the latter case, the strength of the 

 soil solution is so great as to cause the protoplasm to shrink 

 away from the walls of the absorbing cellfun the routs, and thus 

 to prevent those cells from performing their functions, finally 

 causing the death, of the plants through starvation. Under 

 conditions of comparative drought, the tendency is for 

 soluble salts to be brought constantly into the upper layers, 

 in water which passes upward through the soil by capillarity,' 

 and is evaporated. This shows that leaching, or the travel- 

 ling of water downward between the particles, is necessary 

 in all soils, in order to prevent an unwonted accumulation of 

 soluble salts in the upper layers Where this has gone on to 

 such an extent that there is an excess of sodium carbonate 

 in the soil,^ a remedy is sometimes found in applications of 

 gypsum. Explain the action of gypsum, in this connexion. 

 The only effective remedy for the condition that has 

 just been described is drainage. It is necessary, in fact, that 

 all fertile land should be properly drained, not only for the 

 removal of the excess of water that it may contain, but for 

 preventing the accumulation of soluble salts in the way 

 that has been described. It is evident that, as the amount 

 of rainfall varies throughout the year, the quantity of 

 soluble salts at a given level in the soil must differ with the 

 season of the year. This is a subject that has been worked 

 out to a considerable extent in temperate climates; there is 

 not much information, however, as to what definitely takes 

 place in .soils in the tropics. Though the matter is not likely 

 to attain any large direct importance in the West Indies, it 

 is of interest to remember that one of the reasons for carrying 

 out effective drainage, as well as tillage and mulching, is to 

 prevent the accumulation of salts in the soil to any degree in 

 which they may be inimical to the growth of plants. 



Questions for Candidates. 



PRELIMINARY QUESTIONS. 



(1) To what extent does the selection of cotton .seed 

 benefit the succeeding crop. What is the .use of raising new 

 varieties by crossing? 



(2) What precautions are observed in growing plants 

 from cutting.s, and what are the reasons for their observance? 



(3) How would you show what is meant by capillary 

 attraction? 



INTERMEDIATE QUE.STIONS. 



(1) E.'cplain what is meant by the water talile in soils. 

 How is the water table affected by drainage and tillage? 



(2) Describe the appearance of a section made through 

 the woody stem r,f some common plant, and state the uses of 

 the dirterent parts seen with the naked eye. 



(3) State what you know of the relationship between the 

 direction and spread of the roots of a plant and the drainage 

 system of its leaves, illustrating your answer by means of 

 examples. 



FINAL QUESTI0N.S. 



(1) Di.scuss the relationship between the retentive power 

 of a soil and the kinds of manures that are most suitable 

 for it. 



(2) Give an account of the manner in which the soluble 

 salt content of a soil is increased, and state how this increase 

 may be prevented. 



(3) Pre.sent a general discussion of the ways in which 

 mulches are of use to the agriculturist. 



