ERADICATING WEEDS

Timaru Herald, Volume CXXXVII, Issue 19626, 21 October 1933, Page 15

ERADICATING WEEDS

USE OF SULPHURIC ACID. Two overseas scientific Journals recently gave prominence to the use of sulphuric acid as a spray for weeds. They described a service by a gas company which undertakes to remove weeds by contract from any farm within 100 miles of London. While not a new method, it is one that has only in the past few years found favour in France, Germany Scandinavia and the United States. The practice was started in France by Rabate in 1911, and so successful has it been that several hundred thousand acres are now treated annually. In 1931 no less than 27,000 tons of acid were used, and as many as 20 manufacturers were producing suitable spraying apparatus. In that year, two scientists from the School of Rural Economy and Soil Science of Oxford were invited by the National Sulphuric Acid Association to visit France and report on the process. The next year, as a result of their investigations, full scale experiments were made in England.

One great value of the method Is Its Independence of weather, a few hours without rain enabling a fair acreage to be sprayed. The acid is used in a •trength of between 7 per cent and 10 per ceht at the rate of 100 gallons of the mixture to the acre. The principal use in England has been in the eradication of charlock in grain fields. The acid rapidly kills the larger-leaved charlock. Although the whole field Is browned in an hour, the cereals green up again In a few days and the growth Is stronger than ever.

In England the cost is from 12s 8d to 15s an acre, but on a large scale the costs are much reduced. Against this Co6t we have the saving of soil nutrients by the elimination of the weeds, the increased ease of crop cultivation. the reduction of crowding by the weeds and the added plant food from the dead weeds.

When the work is done by contracting firms which own the spraying machine and provide the labour the farmer does not have to incur the risk of using the acid. Sulphuric acid is always dangerous in the hands of one unused to it, and the mixing with water in itself, has to be done carefully. Again, the operation is only likely to be needed at certain seasons of the year, limited to a few weeks only in some districts, and the horsedrawn spray can cover a large amount oif ground in a day.