Impact of agricultural management practices on the nutrient supply potential of soil organic matter under long-term farming systems

Author(s)
Sarker, Jharna Rani
Singh, Bhupinder Pal
Dougherty, Warwick J
Fang, Yunying
Badgery, Warwick
Hoyle, Frances C
Dalal, Ram C
Cowie, Annette L
Publication Date
2018-01
Abstract
<p>Soil organic matter (SOM) has the potential to supply substantial quantities of nutrients [<i>i.e</i> nitrogen (N), phosphorus (P) and sulphur (S)] for plant uptake. Yet there is little understanding of the impact of management on the nutrient supply potential in soils (particularly, P and S). To quantify N, P and S availability from SOM, surface soils (0–10 cm) were collected from 14 management practices across three long-term (16–46 years) experimental sites under semi-arid (Luvisol), Mediterranean (Luvisol) and sub-tropical (Vertisol) environments in Australia. The practices comprised conventional (CT) and reduced tillage (RT) with mixed farming, no-till with continuous cropping (NT), and perennial pasture (PP) in the semi-arid Luvisol, while in a Mediterranean direct-drilled continuous cropping system, stubble was either retained (SR) or burnt (SB). Practices on the Vertisol comprised a factorial combination of CT, NT, SR, SB with either 0 (0N) or 90 kg urea-N ha<sup>−1</sup> (90N) in a continuous cropping system. Soils were incubated under controlled soil moisture and temperature, and cumulative organic C mineralised (C<sub>min</sub>), and net available N, P and S were measured over 126 days. In the semi-arid Luvisol, CT and/or RT showed significantly higher C<sub>min</sub> and net available N, P and S than NT and PP. In the Mediterranean Luvisol, C<sub>min</sub> and net available P were not influenced by stubble management. In the Vertisol, CTSR (<i>cf</i>. CT-SB and NT-SR/SB) with or without N fertilisation significantly increased C<sub>min</sub>, and CT-SR and/or -SB with N fertilisation (<i>cf</i>. CT-SR/SB without N fertilisation and NT-SR and/or -SB with or without N fertilisation) significantly increased net available N and P. This study found a continuous release of net available N (11–49 kg N ha<sup>−1</sup> over 126 days) across all management practices, whereas, the release of available P and S was evident only during the first 30 days (6–74 kg P ha<sup>−1</sup> , −4 to 22 kg S ha<sup>−1</sup> ), after which microbial immobilisation or clay fixation of P and S predominated, particularly in the Vertisol. In conclusion, the results indicate that SOM is a ready source of plant available P and S (in addition to N), and tillage and stubble retention generally enhanced SOM mineralisation and nutrient release, which varied with soil type.</p>
Citation
Soil & Tillage Research, v.175, p. 71-81
ISSN
0167-1987
Link
Publisher
Elsevier BV
Title
Impact of agricultural management practices on the nutrient supply potential of soil organic matter under long-term farming systems
Type of document
Journal Article
Entity Type
Publication

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