Agricultural Chemistry

Bruce Herald, Volume XXVI, Issue 2647, 7 May 1895, Page 3

Agricultural Chemistry

LEOTURE BY MR F. M. ALLAN. A leoture waa delivered in the Counoil Chambers on Thursday, night by Mr F. M. Allan, agent for Meßera Kempthorne, Prosser and 00., on the subject of agrionltural chemistry. There waa a good attendance, Mr D. Tweedie (president of the Farmers' Club) occupying the chair. The ohairman, in introducing the speaker, said Mr Allan was in Milton Borne time ago, and delivered the first part of his leoture, which he intended to continue that night. He was very pleased to see suoh a large attendance, Mr Allan said aB the ohairman bad just intimated bis leoture that night would be a continuation of that delivered by him on a previous vißit. In the former lecture he deal t with the subatanoes from wbioh manures were made. There were four Bubstanoeß which were neceseary to plant life, and not only were they necessary, but they were the only four whioh they needed to add to the soil for giving crops. There were about thirteen subatancea altogether which were necessary, but moat of them were already in the Boil in sufficient quantities. Theae four substances it had been found, by experienoe, were taken from the soil, which had to be replenished, the reaaon being that they existed in smaller quantities than the others. They were, nitrogen, phoßphates, potash and lime, and anyone who wanted to study the matter muat be as familiar with thoße names aa a ohild with the alphabet. To deal first with class 1, nitrogen. Thia existed aa a gas very largely in the air. It had been shown that some plants had the property of absorbing nitrogen from the air. They also got it from sulphate of ammonia, which was made from coal tar at tbe gas works. Nitrogen waß plso found in nitrate of soda. Ammonia was alao obtained in the form of superphosphates from bones, blood, hoofs and horns, while it alao existed in Peruvian guanoa. Phosphates were obtained from rock phoaphateß. They had to be finely ground to produoe any effect, and it waa not till worked up with aulphuric acid that they got their full value. Phosphates were alao got in the guanos met with about this district. There was a large proportion of phosphates in bones, and it was in tbis form that they got phoaphatea in their beat state. The only deterrent from the ÜBe of phosphates in the form of bonea was their alow action, and that waa the reason why superphosphates were made. By mixing them with aulphuric acid the b.nea became soluble in water, when they would aot more readily in the soil In praotioal experience it was found that soluble manures were better in one Boil, and insoluble manurea better in othere. There were only two main sources of potash. One large source waa wood aahea. In America large quantities were made in that way. Thia accounted for the wonderful oropa of grasa whioh they alwaye had after the buah was burned. The other large source waa from deposits in Germany. They had all heard of kainit, the crudest form of potash) but it was not muoh used. The use of potaßh waa not attended by great Buccess, aB they were not very clear of what real use it was to the Boil. Many people had tried to manure only with kainit, and the reßults had been nil 5 still, that was not to Bay that if there were a aufficient amount of phosphates in the ground the kainit mightnot haveagood effect. He knewof some cases where the uae of kainit had been attended by highly benifichl results. Aa to lime it waa not neoeasary to tell them the Bource of that. Ihe part whioh he intended to deal with in his leoture that night waa that which embraced the uaes to wblch manurea were put. Different crop3 requireed different manurea. He could truthfully say that thousands of pounds were wasted through uaing the wrong manure on the wrong crop. All crops were benefited by those four manures to a oertain extent, but they were all benefited to a greater ex'ent by one of them. That was what had given riee to the uae of special manures. The other ingredients were there, but the particular ingredient waß put in in larger quantity. The only way they had been able to find out the best manures was by actual experience, and any of those present could try the matter for themselves. If they took any Boil which had been cropped several timoa and added those ingredients one by one, they would find out by that means which element* were lacking and whioh were not. Before going further he might state that lime was always assumed to exist in the soil already. It was added in different ways, but tbe limo which they got in combination with sulphate and phosphate waa not the aame as qui.k lime, and exerted a different effeot. Suppose they wanted to try an experiment oa potatoes 1 1 find the paiticular manure they required or what was lacking in the soil ; they would firat lay out four plots. In the first they would put no manure ; in the Becond manure lacking ammonia ; in the third manure lacking nitrogen ; and in the fourth manure lacking phosphates. Wh.u they weighed the en ps they would fiod the first-named the poorest. A-j potatoes n - quired potaßh they might expeot a very low yield in the plot where there waa no potash. l In the crop wanting nitrogen they also had a small orop, though not so Bmall as in the lastnamed, the aame also applying to phospha'es. The inference waa that as the potato orop required potash principally they must use a lartfc quantity of potash iu the manure. If they ioand they had aa good a orop without potash aa with it, it would mean that there was already plenty of potash in the soil. This remark applied to all manurea and all crops. These were experiments which they ought to try. He knew that they required a great deal of time and patience, as well as involving expense. It was almost impossible to get people to devote the time and patience necessary, and nnlesa they were oarrl d out very correotly in every respeot they were useless, aB they gave misleading- aocounts. He thought experiment stations should be set up in the different d s'ricts, as there waa nothing more useful to the former. The objection would be raised that thpy would bave to try every paddock in the country. There was a oertain amount of truth in tbat, but if they had an experiment station in tbe centre of each distriot it would confer a lot of benefit. The first class of manure he would deal with was the nitrogenous manuree. The crops improved by tbem were wheat, barley, oats, rye, meadow and pasture graßS, aod garden vegetables. He would take as an example -he average wheat crops grown at Sir John Lawes' experimental farm, Rothamsted, Eagland, continuously for 32 yearß. The results we r e tabu'ated into four periods of 8 years each, as follows : — Bushels per Acre.

The strong point was the difference between the second and third manures, showing that tho essential manure for wheat was nitrogen, only that the others must be used at the same time. If the soil was deficient in potash and phosphates no matter how much nitrogen they had they could not get a good crop, as they must have everything. The amount of nitrogen taken from an acre of Boil by an average crop of wheat was 45ib, while barley took 47 ib and oats 521b. This would show what an enormous exhaustion was going on. The amount of nitrogen in the Boil was far more than that ; but the ques» tion waanot what amount they had in the soil, but what amount waa available for plant food. Tbey often heard people speaking of a chemical analysis of the soil and getting their manures by the results. This, however, waß utterly falUcioua. Chemistry was not yet developed to the extent tbat it oould tell what manure wai required, For instance, phosphates might be present in large quantities in the soil, but if not in a condition in wbioh the plant could get their use they were of no good whatever. Only that amount was of any übo whioh waß soluble in water. By chemical analysis they were often able to tell how much lime there was in the soil, and whether it was in a form to liberate the other elements whioh were useful to plant life. But by experiments Buch aa those of Sir John Lawes the farmer could tell what he required at onoe. If a crop required potash, and they bad a poor yield there was a defloienoy ; if a good yield there was plenty ; and eo on. Though nitrogen was Bhown to ba principally essential for wheat, potash and phosphates were also neoessary. Whichever ingredient was most required was oalled tho dominant fiqn* itftnegt, 83 that uitrcgw mighi fee ggfd, tja

be the dominant constituent in mannre for wheat-growing. Another experiment was made in France with the wheat harvest of 1863, to show the effeot of mineral and nitrogenous manures with thia resnlt :— Buahela per aore No manure 12 Nitrogenous manures only *2 Mineral manure (phoaphate and potash) 18 Mixed manure (nitrogen and mineral) oOJ Thia showed what there waa in manuring when wisely and aoientifioally oarried out, and that money could be saved by adding manures in proper quantities and in proper soils. Another instance taken from French experiments on poor eoil gave remarkable reaulta. On the first plot no manure was pat, whl/e the second wae heavily manured, ap to £3 per acre. On the first the orop waa grown at a heavy loss, and on the second there waß a good profit per acre. What made up to a certain extent for the nae of nitrogenous manures waa the praotioe of feeding sheep on turnipa, as the droppingß contained a large quantity of nitrogen. But where oereala were aown on land without feeding sheep nitrogenous manures should be used, and where phoaphateß were used they ahould be uaed in the I form of superphoßpbate. A farmer had once 1 told him that hia land was so heavily manured that the orop lay down. What he did was to put oq bone aßh, the nitrogen being burnt out and nothing bnt the auperphosphate left. Th.B hardened the crop and kept it from lying down. A farmer had recently experimented in the Taieri diatriot. He pnt 2 owt of Buperphoaphate into the Boil before growing oatß, Now tbis waß not an essential for growing groin *, but it gave 20 bushels per aore more, the reason being that there waa plenty of nitrogen in the soil but not enough phosphateß. He now came to the aecond olasa of manures, ia wbioh phosphate waa the dominant oonatltuent. The oropa benefited by phosphate were ohiefly turnipa and awedea ; though there was scarcely any orop whioh it did not benefit. He would give as an example an experiment tried in 1884 with awedea on a light chalky soil and which resulted as follows : — Per acre.

The 2owt of superphosphate per acre was too little, bat the 4owt superphosphate brought the yield higher than the addition of the 2owt of nitrate of soda to the superphosphate, showing that nitrogen was not muoh required. The farmyard mannre gave the best results of all on this light soil, but it did not follow that it would do so on all kinda of soil. The qustion arose in connection with the turnip crop, what form of phosphate was tho best to nße, superphos phate, bonedust or guano. The advantage of superphosphate was that it gave a quick braird, which very often protected the crop from the ravages of the turnip fly, It also contained about a third of ita weight of gypsum, or sulphate of lime. Gypsum was specially good for crover or graßS land, but sinoe _nperphospate had oome into use gypsum bad nearly been negleoted. Superphosphates benefited oropa of all kinds, if the land was in good condition, but where the land was poor it muat be supplemented by other manures. On the whole the best mixture for turnips waß superphosphate and bonedust. The Buperphoßphate gave quick results, and they also had the lasting effects of the bonedust. The third class of manures was the one in whioh potash was the dominant constituent. The crops principally benefited by this substance were clover, lucerne, sainfoin, vetches, beans, peas, potatoes, vines and mangolds. Potatoes were the principal crop. He noticed that they had 25,000 aores under potatoes in New Zealand every year. Experiments had been tried in Franoe, with these results : —

Thia showed that potatoes required the potash more than the other manures. In a further experiment potash was doubled and the phosphate omitted, when there was a orop of 11 tons per acre, showing distinctly that potash is the element most required by potatoes. There was an important exception, however, in regard to the other members of thia class, viz , clovers, vetches, pea?, &c. These crops contained a very large amount of nitrogen, aud yet strange say they left the land richer in nitrogen than before ; and yet they were greatly improved by mineral manures. Let them, for instance, put in a orop of olover, and manure it only with phosphate and kainit. The crop and the root would contain a very large amount of ammonia. It had now been proved that clovtr had the property of absorbing nitrogen from the atmosphere. If they examined th. roots they would find them covered with wart like exoreßoences, whioh had been proved to bo living organisms. That thia j Was the case they could see for themselves | in '.his way. Let them take two plots, sowing olover in both. On the first put mineral manure, and on the other mineral manure and nitrogen. They would find as good a crop on the first a*- on the se ond, showing that the clover getß very little if any cf ita nitrogen from the soil. The praotioal bear log waa this, that it was throwing nitrogen manure away to put it in a clover crop, as it was not required at all. He had noticed thit experiments were being tried at home with the object of innoculating the land with soil on whioh olover had been grown. The organisms spread over the land and aßßisted the olover orop. Another important praotioal bearing waa that they were now going in largely for green manuring in aome places. By sowing a couple of orops of vetches and ploughing them in they increased the nitrogen in the soil. The only point was whether this paid as compared with the expenditure required to procure nitrogen in other forms. There waß another experiment by which anyone could teßt for themselves with leguminous plants and wheat crop. Let them take three plots, sowing wheat and clover in each. In the first put nitrogenous manure, in the seoond mineral manure, and in the third a mixture of the two. In the first they would have a good crop of wheat and poor olover ; iu the second the wheat would be poor and the clover gooJ ; and in the third the wheat would be better than any of the others, but the clover would be do better than in the second plot. The fourth manure was lime. Lime wai uied by plants as food and there must be sufrbient in the soil to give the plants food ; but beyond that itß effects were far reaching. It aoted chemically on the mineral constituents of the soil and released many elements required by the plants. That was why lime made many soils productive which were previously worked out. All soils contained nitrogen, but it was not always available for plant food. The lime had the property of converting the nitrogenous matter and making it soluble in water, and thus available for plant food. Lime also aoted in a mechanical way on the soil. Some soils oontained iron in a soluble state, wben the herbige was always found to be rank. The lime had the property of making it Boluble in water, when they got sweet herbage. It alao had the advan' age of breaking np stiff day land and making it more porous and warmer. Ia conclusion Mr Allan aaid he had thought it better to give them the result of one experiment In eaoh class. If they grasped what manure did for one particular orop they oould apply it to others. What he had given them waß the principle of the whole thing, and they could get a lot of more praotioal information by experiments suoh as he had indioated. In answer to a question as to the respective value of lime as used In this distriot and crushed lime Mr Allan Baid when the lime waa taken from the earth it was in the form of carbonate of lime, and it was burned to get rid of the carbonic acid, so as to get the most benefit from it. In most oasea quick lime bad most effect. If the lime were carted to the field and left for a certain period in heaps tbe oarbonio acid in the air united with it and the lime got back to the state tbey bad paid ao muoh to burn off. He recommended that when the lime was put in beans it should be covered with girth. By putting the liroo directly on the soil they got the total benefit out of ir, Bat to arrive at the revive value they wss bi?9 te c&leulft^

the deterioration in the value of the heaps by going baok to carbonate of lime. He should say, however, that putting on the quiok lime was far better than the old plan, Mr J. Reid, In a few well chosen remarks, moved a hearty vote of thanks to Mr Allan for his leoture. ' Mr Allan briefly replied to the vote and the meeting olosed with the usual compliment to the ohairman.

tons cwt No manure ... ... 3 7 No potash 4 4 No nitrogen ... ... 6 14 No phoaphate ... 7 3 Complete manure ... 11 3

tons owt v 'o manure ... ... ••■ 5 18 2owt ouperphosphate „. ... 9 4 i Do and 2owt nitrate of Boda 9 5£ 4owt Buperphosphate 11 %i 10 tons farmyard manure ... 13 11 _

" - " ] l.ti-'ud 3rd 4tli nvg Uumanu.<»lplot I 10 i W . U .10 13 Mixed mineral manures- i ' (potash and phosphates) ... H> , 15 : H VI 15 Du and 55010* nitrate t>('soda | 31 -iu i 3!' "H 36 14 tons farmyard manure ... 34 3o i 35 :a?i 33