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- Title
SURFACE STRATIFICATION OF SOIL NUTRIENTS IN NO TILL LIMITS NUTRIENT AVAILABILITY AND REDUCES GRAIN YIELD.
- Authors
Radford, B. J.; Cowie, B. A.
- Abstract
Research has shown that the less mobile elements in the soil, such as P, K and Zn, become stratified in the surface 50 mm of soil after several years of continuous no-till cropping. This causes nutritional constraints to productivity when the surface soil becomes dry unless the sub-surface soil is highly fertile or receives appropriate levels of fertiliser. No-till crops grown in the semi-arid, subtropical environment of central Queensland, Australia, are particularly prone to nutritional disorders as a result of surface stratification. The surface soil can remain dry for long periods during crop growth while the roots obtain water stored in the heavy clay soils during the preceding fallow. Consequently nutrient deficiency symptoms have appeared despite apparently satisfactory levels of those same nutrient elements in the 0-100 mm layer, which is the standard sampling depth used to assess soil fertility. The original aim of the 13-year experiment reported here was to assess the effect of tillage frequency and intensity, and stubble retention and removal, on soil water storage, soil nutrient status, and the growth and yield of rainfed grain sorghum in central Queensland. During the first 7 years of research, the mean yields of no till and traditional tillage (disc plough and scarifier) without fertiliser application were not significantly different. As the experiment continued, it became apparent that supplementary nutrition was required. The placement of appropriate levels of fertiliser elements (P, K and Zn) 100 mm deep and 50 mm to the side of each row resulted in large yield responses to no till. The yield of no till in comparison with traditional tillage (both with stubble retained and appropriate fertiliser application) was 147%, 129% and 174% in the final three crops, respectively. These responses also reflect the outstanding potential of longer-term no till that has been demonstrated in other research work in central Queensland. Since mixing of the surface soil (by tillage) gave similar responses, it was concluded that some crop nutrients had become concentrated in the dry surface soil and were therefore inaccessible to plant roots during dry periods.
- Subjects
CENTRAL Queensland; SOILS &; nutrition; CROP growth; NUTRITION disorders; PLANT nutrients; TILLAGE; PLANTS
- Publication
Environmental Research Journal, 2011, Vol 5, Issue 5, p577
- ISSN
1935-3049
- Publication type
Article