Vol. VIII. No. 19.3. 



THE AGRICULTURAL NEWS. 



291 



SUGAR INDUSTRY. 



The Effect of Soluble Manures on 

 Sugar-cane Soils. 

 From the Experiment Station, Honolulu, there 

 has recently been issued Bulletin No. 29 of the 

 Division of Agriculture and Chemistry, Hawaiian 

 Sugar Planters' Association. It contains an account 

 of work which has been taken up in order to gain 

 a knowledge of the action of soluble manures on soils 

 that are used for growing canes, and the following 

 conclusions, arrived at by the author after twelve years' 

 experience, are given here : — 



(1) The profit resulting from the application of fertili- 

 zers or manures will depend largely upon other factors than 

 the chemical composition of the soil. Providing certam 

 plant-food deficiencies represent the chief depressive inHuence 

 on crop yields, the response to appropriate fertilization will 

 be commensurate with the difterence between the limitations 

 exerted upon crop production througli lack of available 

 plant nutrients and the limitations exercised by the next 

 restraining factor in order of importance after the material 

 has been applied. This latter factor may be physical, 

 biological, or climatic in character. 



(2) The relative effects of ditt'erent combinations of 

 fertilizer materials on the growth of sugar-cane when these 

 materials are added to a given soil will be determined chiefly 

 by :- 



(a) The extent to which their several ingredients 

 directly or indirectly lessen the deficiencies of available plant 

 nutrients ; 



(b) The extent tn which they cause the bacterial flora 

 to approach an optimum balance for the regular production 

 of sufiicient nitrates or assimilable nitrogen compounds, and 



(c) The degrees and manner in which they produce 

 physical changes in the soil. 



(3) Owing to the fact that a definite relationship exists 

 between the efficiency of a fertilizer mixture and the 

 quantities and proportions in which its ingredients are 

 associated, due to biological, chemical, and physical effects 

 which its component parts have in a given soil, variations in 

 the composition of the mixture beyond certain limits may 

 materially influence crop yields. 



(4) A more definite knowledge concerning the amounts 

 and proportions of fertilizer salts to use in a mixture for best 

 results would on .some soils yield pronounced profits, while 

 Ti lack of such knowledge may in .some cases result in a loss, 

 especially when soluble salts are employed. 



(.5) The greatest loss from the use of improper mixtures 

 of fertilizers is apt to occur on acid soils, and in such cases 

 ccmsiderable risk is involved from the continued application 

 of mixtures containing ammonium sulphate, sulphate of 

 potash, and acid phosphate, when lime dressings are not 

 previously made. 



(6) While the chemical and physical analysis of a soil 

 will usually prove of value in indicating the best cultural 

 methods to follow in maintaining or improving its fertility, 

 and may also indicate in a general way certain of the plant 

 food deficiences in given cases, it cannot afford definite 

 information as to the amounts or proportions of ingredients 

 in fertilizer mixtures which will give maximum returns. 



(7) It is possible tiiat the data from more extended field 

 experiments with a large variety of soils, when reviewed in 

 connexion with the comparative analysis of the soils, using 

 both weak and strong acids as solvents, may indicate a .some- 

 what definite relationship between the analytical figures and 

 the order of importance which pho.sphoric acid and potash 

 should assume in cane fertilizers in given cases. 



(8) It would appear that analyses of soils, with more 

 special reference to their physical qualities, reaction and 

 content of organic matter, nitrogen, and more readily soluble 

 lime, may, with due consideration of the water supply and 

 climatic conditions, be relied upon to indicate such manurial 

 treatment as will result in a profit, although they will not 

 afford definite information as to the weights and proportions 

 of the ingredients in fertilizer mixtures which will result in 

 maximum efficiency. 



(9) Nitrogen is the most important element to be con- 

 sidered in the fertilization of the sugar-cane in the Hawaiian 

 Islands, and when applied in mixed fertilizers some risk of 

 reduced efficiency is entailed if either the potash or phos- 

 phoric acid (in the form of soluble salts) is made to exceed 

 the weight of this element. 



(10) Unless through past local experience or carefully 

 conducted field tests it has been definitely determined that 

 a modified formida may be expected to give greater yields, 

 it is safer, when applying nitrogen, potash and phosphoric 

 acid in the form of soluble salts, to have the mixed fertilizer 

 contain even quantities of these elements, which are not to 

 exceed 60 lb. per acre in the case of each element. 



(11) Field tests with fertilizers whose ingredients are 

 mixed in varying proiwrtions will, if such experiments are 

 accurately and scientifically conducted through a sufficient 

 period give the most reliable information as to the best 

 manurial practice. Such experiments should be laid out in 

 very long, narrow, parallel, and contiguous plots or strips, 

 with the untreated control areas lying immediately adjacent 

 to the fertilized cane. 



(12) The great importation of ' resting ' fields in rotation 

 on Hawaiian plantations, and growing upon them legumi- 

 nous crops is very clearly indicated. This applies more 

 particularly to the irrigated plantation.s, where the supplies 

 of organic matter are, in the majority of cases, becoming 

 greatly reduced through successive tillage operations in 

 a comparatively arid climate, and by the favourable con- 

 ditions created for bacterial activity through regular irriga- 

 tions under uniformly high temperatures. 



Points of a Good Sow. 



The body of a good sow is long, deep and comparatively 

 narrow. It should be remembered that the digestive organs 

 of the brood sow i)lay, perhaps, the most important part in 

 her career. They are called upon to do more work at certain 

 times than the digestive organs of any other animal, and the 

 success of her litters is largely determined by the amount of 

 food which those organs can make ready for conversion into 

 milk. Hence it is, that length and depth in the body are exceed- 

 ingly important features in a sow for breeding purposes. 

 The next thing to look for is a well-formed udder, free from 

 badly developed patches or calloused parts. The phlegmatic, 

 sleepy sow is to be avoided. Good mothers are generally 

 somewhat nervous, like dairy cows. Milk secretion has been 

 proved to be largely a nervous function, and the dull, som- 

 nolent cow is seldom a mother of a high order. A good 

 backline is a useful point. Hollowed backs are not safe ; 

 they .should at least be level, and, if slightly arched, so much 

 the better. {Journal of Af/riridtnn', Western Australia.) 



