U.S. Scientists Studying Soil Compaction Remedy

Press, Volume XCI, Issue 27678, 7 June 1955, Page 5

U.S. Scientists Studying Soil Compaction Remedy

(U.S. Information Service]

WASHINGTON. Scientists and farmers in the United States are attacking the universal problem of soil compaction, which greatly hampers world agricultural production. When soil is tightly packed, plant roots cannot struggle through it or can move only with the greatest difficulty. Soil compaction is sometimes a natural condition or it may be created by the traffic of heavy tractors or other farm machinery. Scientists call the man-made compaction “induced” and the naturally-developed condition “genetic.” Federal and State scientists know that the physical properties of soil can be a major factor in limiting production in spite of the increased use of new fertilisers, new insecticides, new crop varieties, irrigation, drainage, and other production aids. The United States Department of Agriculture and State agriculture agencies throughout the country are cooperating in a broad campaign of experimental work with the varying soils, conditions and treatments. Scientists are studying the phenomena of soil disturbance to discover in detail how soil becomes compacted and how the compaction may best be corrected. They yill then test commercial tillage machines, improve them, and develop others. They are doing research with small-scale model machines to expedite development. With departmental co-operation, State agriculturists feel that specific treatments will eventually be found for each type of compacted soil. They believe that success will be speeded through the use of science teams of

agronomists, engineers and soil physicists. The scientists are already better able to study the problem through a device called a “densitometer.” This tool, invented by a New Jersey State soil physicist, uses gamma rays for quick, accurate measurement of soil density. Tests with the densitometer take only a small fraction of the time and labour previously required and can be made as often as desired to follow changes in soil condition broughet about through treatment. Value of Deep Tillage Recent studies have shown that deep tillage, which shatters machine-made compacted soil, can increase yields in certain years but that its benefit may last only a single season. Deep tillage alone has not been very successful with “claypan" (a clay layer just beneath the ploughed surface). Scientists are seeking answers to these specific questions: (1) What soil conditions respond to deep-tillage operations? (2) How long does the effect of such treatments last? (3) Should additions such as lime and fertiliser be placed in the plough layer? (4) How can such additions best be placed? (5) Should deep-rooted legumes be planted occasionally to penetrate and hold open the ploughed soil? (6) What chemical and physical factors limiting plant growth can be overcome? (7) What types and designs of equipment will give maximum results in treating compacted soil? (8) Can the development of compacted layers be prevented by the use of deep-footed crops, or by eliminating certain common tillage operations?