LIME APPLICATIONS

Wairarapa Times-Age, 11 March 1941, Page 9

LIME APPLICATIONS

DIRECTIONS FOR BEST USE SWEETENING THE SOIL. SOME SIGNS OF DEFICIENCY. A leaflet was issued recently by the University of Leeds and the Yorkshire Council for Agricultural Education on the subject of "Lime and its Uses on the Land.’ The leaflet states: All forms of lime are produced from limestone or from chalk. These are chemically the same substance,- namely calcium carbonate or carbonate of lime. Limestone and chalk are sometimes used on the land as ground limestone and ground chalk without any treatment other than grinding. They are effective only if ground to the state of fine flour. If either of these forms of calcium carbonate is burnt in a kiln or in a clamp, it loses nearly half its weight in the form of a gas (carbonic acid gas),and what is left is called quicklime, known chemically as calcium oxide. This may be applied directly to the land in the form of lump lime, or it may be ground and. bagged and sold as ground lime. Quicklime produced in some quarries is sometimes slaked with water and the product bagged and sold as hydrated lime.

Varying amounts of impurities may be present in these materials. Thus, some brands of quicklime are declared to contain as much as 96 per cent, calcium oxide whereas others may contain as little as 70 per cent. When fairly pure, 1 ton of quicklime is equivlent to 28cwt. of hydrated lime and to 36cwt. of carbonate of lime. There are many industrial waste products which can be used for liming, such as beet factory waste lime, tannery waste lime, soap works waste lime. etc. All of these owe their value to their content of carbonate of lime, but they usually contain more than half their weight of water, and consequently as much as four tons must be used to produce the same result as one ton of quicklime. The benefits derived from lime may be enumerated thus: (a) Lime is a plant food, and is necessary for all crops. (b) It improves the tilth and drainage of heavy soils. (c) It helps light soils to resist drought. (d) It removes "acidity" or “sourness” from soils. Acidity is the main cause of crop failures. (e) It promotes beneficial bacterial activity in soils.

LIME SHORTAGE. Signs of lime shortage are indicated as follow: — (a) On arable land short of lime, the following crops may fail more or less completely: Sugar beet, barley, clovers, turnips and swedes, wheat, carrots, peas, cabbages, etc. (b) Many weeds, such as spurrey, sorrel, mayweed, indicate a shortage of lime. (c) The prevalence of “finger-and-toe” on brassicae is often a sign that lim eis lacking. (d) On grassland a shortage of lime is shown by the presence of a mat of undecayed organic matter, by the appearance of such weeds as sourdock, woodrush, ling, etc., and of such grasses as Yorkshire fog, bent and sheep’s fescue. Lime is being continually removed from the soil. On the average, the equivalent of about 4cwt. per acre of quicklime are removed annually from exery acre of land. The removal of lime takes place at a much greater rate in sandy soils than in heavy soils, and also much more rapidly in arable soils than in grassland. Therefore, light- soils required to be limed more freqeuntly than heavy soils, and arable soils more frequently than grassland.

For grassland the best time to apply lime is in late autumn. When a pasture is matted it requires severe harrowing as well as liming and harrowing is more effective in the moist autumn months than at other periods of the year. In the case of arable land, the most convenient point in the rotation at which to lime is the spring preceding the root crop. The lime should be spread on the last plough furrow and well harrowed in. Where the shortage of lime is severe, the liming should be done as soon as possible, because the beneficial effect of lime is not exercised in such cases until the lapse of seevral months.

The quantity of lime to apply depends on a number of circumstances, chief of whic his the character of the soil. When contemplating liming it is desirable to seek the advance of an agricultural college. Danger of Over-Treatment. For grassland, where usually 11 to 2 tons of quicklime per acre are necessary, the most convenient and economical form of lime is lump lime, which can be placed in small heaps all over the field and spread with a shovel after slaking. For arable land, where the application is less than 25cwt. per acre, ground lime should be used and spread by means of a drill, in the case of large applicatons lump lime would prove quite suitable.

For market gardening purposes hydrated lime is a very convenient form to handle, but is rather more expensive than a corresponding amount of ground lime. Light, sandy soils require liming frequently, and the best form for this type is carbonate of lime, such as ground limestone, ground chalk or factory carbonate of lime. Some soils contain adequate reserves of lime. Further applications of lime to such soils are not only unnecessary but may actually be harmful. Excessive lime promotes a too rapid decomposition of humus in the soil. It may also encourage such diseases as chlorosis in legumes, common scab in potatoes, heart rot in sugar beet, raan in turnips and grey leap in cereals and some root crops. The use of lime in horticulture is just as important as in agriculture, although it is frequently found that horticulturists use 100 much lime. It is important that the soil should be tested before an application of lime Is made. If required. a good dressing is about IJcwt. for 300 square yards applied after digging in the autumn. Ground quicklime is the best form to use. Ground chalk (calcium carbonate) applied in the spring at about 2cwt. for 300 square yards is probably better on light soils. Lime or chalk should never be dug | into the ground but scattered evenly

over the surface after digging. As lime encourages the disease known as "common scab” on potatoes, it is not usually advisable to apply lime just before a crop of potatoes. Lime also encourages worms, weed, clover and coarse grass on lawns, and. therefore lime should be applied to lawns only if it is certain that if is required. The fine grasses which are desirable on lawns grow best in a slightly acid soil.