Murdoch University Research Repository

Welcome to the Murdoch University Research Repository

The Murdoch University Research Repository is an open access digital collection of research
created by Murdoch University staff, researchers and postgraduate students.

Learn more

Influence of organic residues and soil incorporation on temporal measures of microbial biomass and plant available nitrogen

Hoyle, F.C.ORCID: 0000-0001-6946-918X and Murphy, D.V. (2011) Influence of organic residues and soil incorporation on temporal measures of microbial biomass and plant available nitrogen. Plant and Soil, 347 (1-2). pp. 53-64.

Link to Published Version: https://doi.org/10.1007/s11104-011-0922-8
*Subscription may be required

Abstract

Aims
Despite our current understanding of plant nitrogen (N) uptake and soil N dynamics in arable systems, the supply and demand of N are infrequently matched as a result of variable seasonal and soil conditions. Consequently, inefficiencies in N utilisation often lead to constrained production and can contribute to potential environmental impacts. The aim of this study was to examine the influence of plant residue quality (C/N ratio) and extent of residue incorporation into soil on temporal changes in soil mineral N and the associated plant N uptake by wheat in the semi-arid agricultural production zone of Western Australia.

Methods
Oat (Avena sativa); lupin (Lupinus angustifolius) and field pea (Pisum sativum) were incorporated into a Red-Brown Earth using varying degrees of mechanical disturbance (0 to 100% residue incorporated). Soil samples for inorganic N (NO-3 and NH +4) profiles (0–50 cm), microbial biomass-C (0–50 cm) and plant N uptake were taken throughout the growing season of the subsequent wheat (Triticum aestivum) crop. Grain yield and yield components were determined at harvest.

Results
Despite observed treatment effects for plant residue type and soil disturbance, fluctuations in inorganic N were more readily influenced by seasonal variability associated with wet-dry cycles. Treatment effects resulting from residue management and extent of soil disturbance were also more readily distinguished in the NO−3 pool. The release of N from crop residues significantly increased (p = 0.05) with greater soil-residue contact which related to the method of incorporation; the greater the extent of soil disturbance, the greater the net supply of inorganic N. Differences in microbial biomass-C were primarily associated with the type of plant residue incorporated, with higher microbial biomass generally associated with legume crops. No effect of residue incorporation method was noted for microbial biomass suggesting little effect of soil disturbance on the microbial population in this soil.

Conclusions
Despite differences in the magnitude of N release, neither crop type nor incorporation method significantly altered the timing or pattern of N release. As such asynchrony of N supply was not improved through residue or soil management, or through increased microbial biomass in this semi-arid environment. N fluxes were primarily controlled by abiotic factors (e.g. climate), which in this study dominated over imposed agricultural management practices associated with residue management.

Item Type: Journal Article
Publisher: Springer
Copyright: © Springer Science+Business Media B.V. 2011
URI: http://researchrepository.murdoch.edu.au/id/eprint/62376
Item Control Page Item Control Page