Phosphorus and nitrogen in the soil interface between two plant residues differing in C/nutrient ratio: A short-term lab
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https://doi.org/10.1007/s42832-020-0037-3
RESEARCH ARTICLE
Phosphorus and nitrogen in the soil interface between two plant residues differing in C/nutrient ratio: A short-term laboratory incubation study Kehinde O. Erinle, Petra Marschner * 1School of Agriculture, Food and Wine, The University of Adelaide, South Australia, 5005, Australia
ARTICLE INFO
ABSTRACT
Article history:
In studies on the effects of mixing residues with different properties on decomposition rate and
Received November 7, 2019
nutrient release, the extent of contact between the different residues is not known. In this study,
Revised March 7, 2020 Accepted April 19, 2020
we used an experimental design where crop residues were spatially separated by a layer of soil. Microcosms were set up using young faba bean residue (low carbon (C)/nutrient ratio, L)
Keywords:
and mature barley straw (high C/nutrient ratio, H). The microcosms comprised of two caps of PVC tubes, each filled with moist soil. Between the two caps, there were three layers each
Crop residues
separated from the others by fine nylon mesh with the middle layer being the moist interface
C/P ratios
soil. Microcosms had similar (H/H or L/L) or different (L/H) residue types, or only residue type
Interface soil
(H/S or L/S) while the other cap had no residue. In treatments with only one residue, measured
Phosphorus pools
parameters, except microbial biomass P (MBP), were higher in L/S than H/S. In treatments with two residues, all parameters were lowest in H/H. In L/H compared to L/L after 14 days, available P and microbial biomass N (MBN) were lower, available N was similar and MBP was higher. After 28 days, available P and N were lower in L/H than L/L, but MBP and MBN did not differ. In L/H, measured resin P, MBP and MBN were higher than expected whereas available N was lower. The experimental design used in this study allows assessing the effect of residues on properties of the soil between them. © Higher Education Press 2020
1 Introduction The effects of mixing residues with different properties on decomposition rate and nutrient release have been studied extensively. Usually, two or several residues are either placed together in litter bags or mixed into the soil (De Graaff et al., 2011; Shi et al., 2013; Cuchietti et al., 2014; Truong and Marschner, 2018). Then litter mass loss or nutrient release are
* Corresponding author E-mail address: [email protected] (P. Marschner)
measured with litter bags or soil properties are measured in residue amended soil. However in such studies, the extent of contact between the different residues is not known. Further, in experiments with residues mixed into the soil, partially decomposed residues may directly contribute to available nitrogen (N) and phosphorus (P) or microbial biomass which could lead to overestimation of the effect of the residues and their interaction. Interactions in 1:1 mixes with two residues are determined by comparing the measured value with expected value, the latter being the average of the
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