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Spatial variability in pH and key soil nutrients: Is this an opportunity to increase fertiliser and lime-use efficiency in grazing systems?

journal contribution
posted on 30.08.2018, 00:00 authored by Mark TrotterMark Trotter, C Guppy, R Haling, Tieneke TrotterTieneke Trotter, C Edwards, D Lamb
Nutrient-use efficiency is a key issue for grazing systems in Australia. Spatial variability in soil pH and nutrients at the sub-paddock scale may affect the efficiency of utilisation of, and provide an opportunity for, site-specific management (SSM) of fertiliser and soil ameliorants. However, there has been little research exploring the potential for SSM in grazing systems. This study examines the spatial variability of soil test pH, phosphorus (P), potassium (K) and sulfur (S) in two typical pasture fields (a native and an improved) on the Northern Tablelands of New South Wales and evaluates the potential for SSM based on a comparison with critical values. In both fields, the overall paddock mean from a grid survey containing >80 samples for pH, P, K and S (0-10cm) exceeded the critical values, suggesting that the addition of fertiliser or lime was not required. However, considerable sub-paddock-scale variability was observed, with CV ranging from 35% to 66% for the key nutrients (P, K and S). The Sprengel-Liebig Law of the Minimum was applied to evaluate the proportion of each field constrained by one or more soil characteristics. Up to 55% of the improved paddock and 78% of the native pasture was potentially responsive to amendments. The results of this study suggest that SSM of fertilisers and ameliorants could provide substantial improvements in productivity and possibly reductions in fertiliser use. The development and application of appropriate systems and tools to effectively quantify this spatial variability remain a challenge, coupled with management strategies that optimise the placement of amendments and account for the variability in other production limiting factors. © CSIRO 2014.

Funding

Category 4 - CRC Research Income

History

Volume

65

Issue

8

Start Page

817

End Page

827

Number of Pages

11

eISSN

1836-5795

ISSN

1836-0947

Publisher

C S I R O Publishing

Peer Reviewed

Yes

Open Access

No

External Author Affiliations

CRC for Spatial Information; University of New England; CSIRO Sustainable Agriculture Flagship,; Central Tablelands, Local Land Services

Era Eligible

Yes

Journal

Crop and Pasture Science