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Root and shoot response of field-grown lettuce and broccoli to a compact subsoil

Montagu, Kevin D., Conroy, J.P. and Francis, G.S. (1998). Root and shoot response of field-grown lettuce and broccoli to a compact subsoil. Australian Journal of Agricultural Research,49(1):89-97.

Document type: Journal Article
Citation counts: Scopus Citation Count Cited 8 times in Scopus Article | Citations

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Title Root and shoot response of field-grown lettuce and broccoli to a compact subsoil
Author Montagu, Kevin D.
Conroy, J.P.
Francis, G.S.
Journal Name Australian Journal of Agricultural Research
Publication Date 1998
Volume Number 49
Issue Number 1
ISSN 0004-9409   (check CDU catalogue open catalogue search in new window)
Scopus ID 2-s2.0-0031963562
Start Page 89
End Page 97
Total Pages 9
Place of Publication Australia
Publisher C S I R O Publishing
Field of Research 0701 - Agriculture, Land and Farm Management
Abstract The direct effect of subsoil compaction on the root and shoot growth of lettuce (Lactuca sativa ‘Classic’) and broccoli (Brassica oleracea L. Italica ‘Bushido’) was investigated in field experiments. Possible secondary effects of the compact subsoil were minimised through careful supply of water and nutrients to the soil. Roots were sampled at 3 times to determine the timing and extent of root growth into the compact subsoil. The compact treatment had a distinct layer of high strength soil at 0·17-0·35 m, maximum soil strength of 3·1 MPa at 0·27 m. In the loosened treatment, deep ripping reduced the maximum subsoil strength to 1·9 MPa at 0·35 m. The roots of both crops penetrated the compact subsoil approximately half-way through the vegetative growth phase of the shoots. Root growth was restricted by the compact subsoil, with root length densities 60-75% lower than in the loosened subsoil. As a result, only 6-13% of the total root system was present in the compact subsoil. The reduced root length in the subsoil was compensated for by increased root growth in the topsoil, for the broccoli crop only. The compact subsoil had no effect on the shoot growth or yield of either vegetable crop when water and nutrientswere well supplied. This may have been due to the small proportion of roots growing in compact soil and/or the advanced vegetative growth stage of the shoots when the roots grew into the compact subsoil. Consequently, under dield conditions, a compact subsoil had no direct effect on vegetable crop shoot growth or yield. 
Keywords Deep ripping
Mechanical impedance
Root distribution
Root growth
Root length density
Shoot growth
Subsoil compaction
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Created: Fri, 29 Aug 2014, 20:07:12 CST by Anthony Hornby