BROWNS FIELD DAY

Southland Times, Issue 18938, 11 May 1923, Page 6

BROWNS FIELD DAY

A LARGE ATTENDANCE. INSTRUCTIVE ADDRESSES. Yesterday’s glorious weather had the effect of inducing over 200 farmers from all parts of Southland to attend the field day arranged by the Browns Lime Company in conjunction with the Department of Agriculture. The lime works and the quarry were thrown open to the visitors, and many availed themselves of the opportunity of making an inspection. Lunch was provided on the grounds and pleasure was blended with instruction. The main feature of the pregramme was a series of lectures by wellknown agricultural experts. Mr R. B. Tennent, Instructor in Agriculture for Otago and Southland, in opening his address expressed himself as being extremely pleased at seeing such a representative gathering of faribers. His object in meeting them at Browns was not to “boost” any particular company’s lime—he held no brief from any individual lime company—but merely to seize the opportunity of imparting information in relation to the forms and properties of lime. His address would deal chiefly with the chemical aspect of the question and in this respect it should be borne in mind that there were three forms of lime principally used for agricultural purposes in New Zealand. These forms were carbonate of lime, burnt lime, and slaked lime. Carbonate of lime was the raw limestone rock as quarried cut of the hilltide. This form of limestone was usually of a white appearance, and a very white colour usually meant a high percentage of lime. This was not always the case, however, and many high grade limestones had colours varying from yellow to red, this coloration being due to the presence of certain mineral oxides. The only true test for the quality of the limestone was that applied by the analyst, and for agricultural purposes limestone showing anything up to 80 per cent, of calcium carbonate was highly suitable. Burnt lime or calcium oxide was the carbonate of lime converted into a different substance by the application of heat. The effect of applying the heat was to drive off a large percentage of the moisture and gas, changing the lime into a hard substance which absorbed water very readily. Burnt lime was a very caustic form of limestone and in the process of manufacture it lost approximately onehalf of its bulk. This really meant that about half a tone of burnt lime was equivalent to one ton of carbonate of lime, a master of great importance where cartage from the railroad to the farm was. considered. Slaked lime was the resultant product of burnt lime alter water had been applied to. it and .often it had absorbed moiteture from the air. An important thing farmers she did consider was the fact that burnt lime absorbed moisture from the atmosphere. This meant that it could not be stored fcr a long period without reverting into a calcium hydrate. The importance of lime in Southland was tod well known to require stressing, he said, but it would be interesting to discuss briefly the action on the soil. The average soil of Otago and Southland contained a considerable percentage of acidity, such a soil being usually termed sour. This acidity was more apparent in the low-lying hedvy types of land, and here lime cculd be used to the best advantage. The acidity was absolutely inimical to the growth plants in spite of the abundance of other plant food which might exist there. The value of lime therefore in such toils wb.s accounted for by the elementary fact that lime had the peculiar property of neutralising the acidity and making the soil “sweet. To the average farmer lime had in the past been looked upon as a plant food, but such was not the case. Although all plants required a certain amount of calcium in order to make full growth, there was generally sufficient of this element in the soil to ensure that growth taking place. The farmer had therefore to regard lime as being an ideal soil corrective rather than a plant food. The second valuable property of the lime lay in its power of flocculating heavy clay soils. Such soils were usually very difficult to work, this being accounted for by the minute particles which were to constitute clay soils. The effect of lime when applied was to make these small particles, Coalesce thus making the ’ soil much mere granular and in a friable con : dition and more easily worked. By this means stickiness in clay soils was overcome and the physical condition greatly improved. Also, in the past, he said, soil had been looked upon as a connection to. be built by the chemist either by the addition or elimination of certain chemical ingredients contained therein. The soil was looked upon as an inanimate substance which could be so altered by the addition of certain elements that it would suit any plant Such was not the case, for it has been realised that the soil teemed with small invisible organisms which to a large extent directly influenced the plant growth. These organisms might conveniently, be divided into two classes, namely, the soil bacteria and the soil protozoa. The former were very beneficial to the growth of the plant, and the latter were inimical to plant growth m that they inhibit the multiplication of the beneficial bacteria. Generally speaking sour soils contained an abundance of those harmful organisms which prevented the beneficial organisms from asserting their usefulness. Where lime is applied to such soils, especially in the form of burnt lime, the soil became a less favourable medium for the growth of the harmful organisms and stimulated the growth of the beneficial ones. This was cne aspect of liming that was not generally recognised, but which was undoubtedly the most important part. Mr Tennent then showed by a series of instructive and interesting experiments the chemical changes that took place in the soil when lime was applied, and the points dwelt upon were clearly driven home by this means. He then went cn to say that there was a considerable controversy as to which was the best form of lime for the farmer to use. It was hard te compare calcium carbonate and burnt lime, as each had its own particular effect on different types of soil. On heavy clay land he would unhesitatingly recommend the application of burnt lime in considerable quantities with an endeavour to obtain quick action in not only overcoming the acidity cf such soils, but in changing the texture into a texture more suited to cultivation. Burnt lime, being very caustic in action, naturally had the effect of using up a considerable quantity of the organic matter in the soil. As organic matter was of paramount importance in every soil, it naturally followed that in light open country with a low percentage of organic matter carbonate of lime should be used in preference to burnt lime. Generally speaking, a dressing of cne ton of carbonate of lime or half that amount of burnt lime, given annually, should suit most country in Southland, but this was merely an arbitrary amount. The only definite way of assessing the amount of lime to apply to the soil was for the farmer to have an analysis made of such soil with a view to ascertaining its exact lime requirement. This was a service which the Department undertook gratuitously, and any farmer desiring such an analysis made should forward a sample to Mr Tennent.

The speaker then concluded by stating that the services of the Department were at their disposal, and he urged them to avail themselves of the expert advice that was to be obtained for the asking. Field instruction was going ahead in Southland by leaps and bounds, and any talk about closing down the experimental areas was totally erroneous.

Mr W. Alexander delivered a short address on the practical application of lime. He said that every true farmer knew quite well how to apply the lime, but the trouble was he could not gauge its real effect in pounds of butter cr pounds of wool, although this had actually been, done in the Old Country. Great strides had, however, been made in the Winton experimental area, and they could now show the effect of lime on every variety of crop. These experiments were making agricultural histcry in New Zealand.

The outstanding feature of land that had been treated with lime was its freedom from weeds, and this was especially noticeable in the case of stubble land where it was very easy to see by the weeds just where the land w’as limed and where it was not. Lime was especially beneficial in rooting out such weeds as yarr and sorrel and. other acid loving species. Another great effect of lime had was to make stiff clays pliable and loose. This was of the greatest importance because stiff clay kept the moisture away from.the foots of the plant and nearer the surface of the ground where it was liable to evaporate. This evaporation. again, had the effect of lowering the temperature of the ground and thus retarding the growth of the crops. Stiff clay also prevented moisture from below reaching the roots by capillary acticn, and this was the main supply of the plant’s food. On light clay lands lime had the opposite effect, and where the soil was too open it bound it together and enabled it to hold the water for feeding the plants. The greatest effect of lime, however, was seen in pasture lands, of which Southland was largely composed. Lime greatly increased the palatability of grasses by promoting the growth cf clover and other leguminous plant*, of which cattle are so fond. As a rule, however, farmers were too impatient for results. They put lime on a paddock and were surprised at not seeing that there were no appreciable effects within the next few months. They forget that cattle were especially partial to limed pastures and would naturally keep the grass down. A paddock that had been limed should be left until the lime had sufficient time to take effect. The dressings did not need to be heavy, but they should be frequent. At the conclusion of the lecture the Hen. A. F. Hawke thanked both speakers for their instructive addresses, and they were both duly accorded a hearty vote of thanks.