Agricultural Chemistry.

Poverty Bay Standard, Volume IX, Issue 956, 29 June 1881, Page 2 (Supplement)

Agricultural Chemistry.

Mr. R. W. E. Mclvor’s Lecture at Cambridge. (Concluded). “ WHERE SHALL WE GET OUR GYPSUM FROM ?” “It will cost too much money.” Well, I am happy to tell you that the place I I visited some little time ago —White Island—contains hundreds of thousands of tons of gypsum, so if I shut out the cost of railway carriage, which I take for granted is very heavy, you have still gypsum at your very doors in practically inexhaustible supplies, and I think it is a duty that you owe to yourselves to test it upon your land, if not upon a large scale, certainly upon a small scale, to try whether it is good, and then afterwards you can please yourselves whether you will extend ft to larger areas. Having explained to you the character of your land so far as my limited stay will permit, I may now leave this part of the subject, and mention that the manure which will prove most beneficial to your crops is super-phosphate of lime, and, for grass lands, bonedust. You may say to me, “ WHY SHOULD SUPER-PHOSPHATE OF LIME BE USED ?” “ What is the essential difference between super-phosphate of lime and bonedust ?” Phosphate of lime in bonedust is soluble in water to a very limited extent, but by treatment with vitrol this insoluble phosphate, or partially insoluble phosphate, becomes perfectly soluble, in fact, so soluble that it is with difficulty you can saturate water with it. Therefore, the difference between super-phosphate and bonedust is that bonedust is only partially soluble, whereas super-phos-phate is very soluble. Super-phosphate will be useful for the reason that a shower of rain will disseminate it right through the land, whereas in bonedust it will take a considerable shower before it will thoroughly be distributed throughout the entire crop. Bonedust is best in dairy Crops. As phosphatic manure for land in crop there is no better manure to have for a basis at least than super-phosphate. I may now state that your land is rich in potash, and, indeed, I may also say, in most of the constituents of plantfood. The only ones that are likely to be exhausted are those you replace ■with phosphate of lime.

SUGAR BEET. Your land would produce sugar beet in great quantity. First of all, sugarland is not rank, and rankness, or richness, in the soil is repugnant to the production of good sugar and beet. In tne second place, potash is a very important substance, particularly important to a crop like beet, and your soil contains abundance of it. In the third place, so far as I can judge of your climate, from what I have read and seen, it is very suitable for the growth of beet. Considering that your Government is holding out inducements for the establishment of beet sugar manufactories in the Colony, I think it is the duty of capitalists, of those who intend to invest their money in the manufacture of beet-root sugar, to offer some inducements to New Zealand farmers to have the beet-root growing capabilities of the soil thoroughly tested. You are all aware that beet-root sugar growing is a large industry in France, where it affords employment to tens of thousands of people, and it is estimated that an acre of land in beet-root—well cultivated land —yields something like two tons of sugar per acre. That is about an average statement for the beet-root plantations in France. If you remember particularly that beet-root sugar can be grown without your soil suffering any deterioration, any loss of fertility, provided you restore that portion of the waste you take away, either in the shape of giving it to your pigs—for it is very good food —but, at all events, restore the waste, the refuse of your manufactory to your land, and you can go on growing beet-root to all eternity without your soil suffering any deterioration in quality. Well, gentlemen, having thus far sketched agricultural chemistry in its relation to plants and soils and local conditions, I will submit myself to your cross - examination on agricultural chemistry, in order that you may elicit information on points that I have not touched upon in the lecture. 1 have noticed in Victoria that the farmers took a great deal more interest in questioning than in the lecturer. I ask you not to be too modest, and I

will answer anything in reason you may ask me upon agricultural chemistry. (Applause). QUESTIONS AND ANSWERS. The Chairman: After the invitation that has been given to you, I hope you will not be backward in asking any questions, and in submitting to Mr. Maclvor any matters which have puzzled you in the cultivation of your different farms. We all of us know we have difficulty to contend with in this district in consequence of the fern, which is the natural vegetation, but from which other districts, where the natural vegetation is grass, are free. No doubt, everyone in this room has experienced more or less difficulty in the cultivation of wheat, in consequence, as some of us think, of the fern, and the difficulty in which it has embarassed us. If any gentleman wishes to ask the lecturer as to how the fern has interfered with the cultivation of wheat or rye-grass, I. have no doubt he will be ready to give you any information in his power, and as to other matters, as to how the ploughing in of clover operates upon the growth of wheat, upon the influence of growing turnips upon the land, as to the best mode of rendering your lands profitable in the present and the proper means of continuing their fertility. There must be many practical questions that have struck the gentlemen here before me which they will have only to submit to Mr. Maclvor in order to obtain an explanation to the best of his ability. I hope you will not be modest or reticent, but will come forward and ask those questions in the freest manner. FERN ROOT. Major Wilson : I should like you to answer the chairman’s references to fern root. Mr. Maclvor: The supposition is that it contains a large amount of vegetable matter, a very hard kind that will not readily decompose, and the portion that does decompose is not a healthy decomposition, that it only partially decomposes, and produces unhealthy acids, which gives sourness to the land. These unhealthy acids produce unhealthy vegetable matter, and makes the land too loose for the roots of grass or grain to thrive in it. There may be many other causes, but these are the principal causes of the non-fertility of land covered with the debris of unhealthy vegetation.

EFFICACY OF CLOVER. With regard to that other question of clover, I may mention that clover acts beneficially on the land in two ways. First of all, it has long roots that go a considerable depth, and more especially in soil of so porous a nature as much of the soil in this neighborhood is—they go to a considerable depth and bring up from that depth the plant-food which would be unavailable, say, to the wheat plant. You plough in clover as green manure, it rots readily, and the surface is enriched with what the plant has brought from a depth. Then when the decomposed vegetable matter of the clover is split up there is left on the surface, or near the surface, a large amount of readily available plant-food, proper plant-food that has been adjusted and assimilated, and given up again by the clover plants. It was formerly believed that clover absorbed from the air nitrogen and in decomposing put ammonia in the soil, but this assumption is not taken at all for granted, and the balance of evidence is not in favor of the assimilation or taking up of nitrogen by clover. Then, again, clover in growing assists the surface soil because it affords shade, keeping it moist, and as a consequence the plant-food that is in the surface soil that might not have been available becomes soluble through the presence of water, and, further, when the clover in growing let its leaves fall the leaves on the surface act both as shade and manure. The main functions of the clover are that it is deep-rooted, and brings from a depth the plant-food that is unavailable for other root crops, and in decomposition leaves behind a considerable portion of soluble and immediately available plant-food.

The Chairman : If nobody else comes forward I must do so myself again. Knowing it was the intention of Mr. Maclvor to give a lecture to the Cambridge Farmers’ Club I had previously invited him to spend a few days at Matamata, and taken every opportunity to make him thoroughly acquainted with the soil on the plains, knowing that it would be interesting to me and a large number of the residents in the Waikato district. I have

taken every opportunity of travelling through the district to examine the soil and sub-soil in order that Mr. Maclvor might be enabled to give you information as to the constituents. I am not quite sure that you apprehend the statement made by him, which, with his permission, I will repeat : That the soil of the Matamata Plains and Waikato Plains are as nearly as possible identical, their mineral and chemical constituents are as nearly identical as soils can be ; as I know and you know when we first began to cultivate our lands we found them covered with fern grow'th, and that after the fern has" been burnt off the soil is exceedingly loose, so that when you ride over the land your horse sinks in it to the fetlocks. He has explained to you the cause of this, which is the characteristic experience in Matamata and Waikato lands. He has explained to you how it affects the land from a chemical point of view in consequence of the sour substances which il has absorbed from the fern roots. Now, I know r there are certain questions w'hich have troubled you and me, and I shall be very well pleased if you will avail yourselves of the opportunity of questioning a gentleman of his high culture and great attainments in agricultural chemistry. I have no doubt that you are all acquainted with the peculiarities of this district, for instance the exhaustion of clover. You find, after laying down land, and after getting clover abundantly for three, four, or five years, that the clover seems to disappear. Now, I think a very pertinent question would be whether it is possible to restora this clover-producing power which the land originally possessed. Mr. Maclvor : Well, one of the strongest arguments used by scientific men in favor of crop rotation is the instance mentioned by Mr. Firth, that clover crops, after being grown on the land for three, four, or five years, die away. In the old country a soil that is tired of growing clover is said to be “ clover-sick.” A good many years ago Lawes and Gilbert, two men to whom the scientific w'orld is indebted, who have directed their atttention to the science of agriculture for 25 years, stated that they had grown wheat for 15 years on the same land, but they would not attempt to do the same thing with clover. They put in clover on clay soil, on the same kind of soil on which they had been growing wheat without success, and got an abundant yield of clover, and the following year they sowed the same land and got an abundant crop. The third year they got a good crop, but slightly less than the previous year, but they found that in the next and the fifth year the land was not worth a crop. They tried the; experiment in every way. First of all the land was unmanured, and then it was manured with gypsum, but yet in the fourth or fifth year the clover fell away. They came to the conclusion that the “ clover-sickness ” was not due to any exhaustion of the soil, but to some outside cause. So far no agricultural chemist had been able to explain why clover died out in that way ; they merely said the land had become “ clover-sick.” Lawes and Gilbert, however, saw that they could put in clover for one year, but they would have to change the crop in the following year. They therefore came to this conclusion, that they could not depend upon a clover crop oftener than once in three years, but that in order to keep up the land they could sow one crop of wheat and another of clover. The result of that is that though you may sow clover once in three years it is a dangerous thing to go beyond that. The only remedy they recommend for the “ clover-sickness ” is the introduction of another crop between the clover. Suppose the land has been in clover for three years, take another crop, wheat, or some other crop, the local circumstances will determine that, and then put in clover for a number of years. This, I think, is all that is absolutely known regarding the curious phenomena of “cloversickness.”

SORREL. Mr. Runciman : I should like to ask what is the reason our lands run to sorrel ? I suppose you know the plant we call sorrel. Mr. Maclvor : I do not think it is any peculiarity of your lands to run to sorrel, because it is pretty common in all the colonies, and I have found some of the richest land to run to sorrel No doubt the cause is not due to impoverishment of the soil, but simply to some reason of nature that we cannot very well account for. It turns up in our crops in spite of all our care. It seems to be a great nuisance all over Aus-

tralia. If you so arrange your system of cropping as to destroy the plant when it is young it does not occasion much injury, but when you allow it once to come to maturity you can only with great difficulty extirpate it. The only means is to apply burnt lime, but that is expensive. There is no other way but to so arrange your crops as to get it out when it makes its appearance, with a view to serve the function of green manure. If you prevent it seeding, w’ell and good, but if you once allow it to seed there is no means of getting rid of it but turning up your land. THE USE OF SALT. Mr. J. P. Campbell: Would the use of salt have any effect in preventing sourness in the land ? Mr. Maclvor: No effect. According to the general impression salt is not a manure. Salt is a means of tempering the land, of destroying rankness, that is to say preventing wheat crops becoming too long. It makes the straw strong. It is valuable not because it increases the amount of grain, but because it makes soluble in the soil certain plant food. Its main function in agriculture appears to be to prevent the excessive development of foliage, and at the same time to increase the growth of roots, thereby preventing that increase of foliage. It is rather a difficult point to explain. If you have a strip of land in suitable condition to put in potatoes, salt is not a good thing to put on. If you have two strips of land to one of which you apply salt and the other none, supposing the lands are in really good heart, you will find that weight for weight you will get more tubers and less foliage from that to which salt has been applied than from the other. The main function of salt is to prevent over-development of foliage in the case of root crops.

A gentleman asked a question which was not clearly audible as to why sandy land would favour roots or barley. Mr. Maclvor: If you take surface soil you will find it pretty homogenous, throughout you will notice dark particles. If you take a quantity of this sort of gravel and examine it you will find that it consists of a lot of more or less decomposed sand, and if you break this, as it can be broken between the fingers, you will notice the different crystals that originally composed the rock, dark, light, and other colours, but if you take a handful of smaller gravel and pull it over in your hand, and examine it very carefully, you will see distinctly the minerals that composed the rock, felt spar, pink or brown .minerals, and black-looking minerals that contain a lot of lime and other substances. It contains a large amount of those minerals which were originally decomposed rock, aud which when brought to the surface and broken up produce a beneficial effect upon the crop. That is to my mind the only natural explanation. You can put it in this way —that the gravel will contain more plant food, whether lockedup or available, than an equal weight of surface soil. The Chairman : I should like to ask whether it may not be a judicious plan to apply salt as manure, to scatter it about our pastures for the purpose of giving our cattle salt lick.

Mr. Maclvor: There is no man who will doubt for a single moment that salt is not beneficial to stock. I have met one man in my life who has given up salt, and has imagined that because he dispensed with it that sheep and cattle can do so. He forgets that our' body contains salt, and that because he does not put a small quantity of salt at the edge of his plate nature will not allow' an animal to live without salt. You may prefer to scatter rocksalt over the land so that the sheep may get at it if they want it. The farmer who has salt on his land will find it all the better for his stock. I may mention that for centuries it has been the law in Spain that the people who have large blocks of land shall supply for every 1000 sheep at least 128 Bis. of salt per annum. This is absolutely necessary, so that the value of salt for maintaining the growth of stock must have been long since recognised by the Spanish people, and I have no doubt that if we had time to inquire into the history of other countries we should find that some provision has been made for the supply of salt to the stock. There is no use arguing about it. I have no hesitation in saying that if salt were more generally used in upcountry stations you would hear less of fluke and parasitic diseases that effect your stock.