Degradation and restoration of soil structure in a cracking grey clay used for cotton production
1989
Daniells, I.G. (New South Wales Agriculture, Narrabri (Australia). Agricultural Research Station)
A field experiment involving irrigated cotton investigated the effect of tilage on a self-mulching cracking grey clay at 3 different soil water contents over 3 years. Compared with tillage of dry soil, tillage of moist or wet soil depressed lint yield by 35 percent. Shrinkage curves of resin-coated, intact soil clods showed lower clod bulk density at a standard water content in the dry treatment than in the wet treatment. Subsequent restoration treatments showed that, although wheat improved soil physical condition, the yield of a following cotton crop was reduced due to lower nitrogen uptake. To preserve the structure and productivity of cracking clay soils, they should be tilled only when dry to permanent wilting point through the full depth of tillage.
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