Wheat Growth-Induced Changes in Phosphorus Pools in the Crop Residue Detritusphere Are Influenced by Residue C/P Ratio
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ORIGINAL PAPER
Wheat Growth-Induced Changes in Phosphorus Pools in the Crop Residue Detritusphere Are Influenced by Residue C/P Ratio Kehinde O. Erinle 1
&
Petra Marschner
Received: 8 June 2020 / Accepted: 11 August 2020 # Sociedad Chilena de la Ciencia del Suelo 2020
Abstract This experiment was carried out to elucidate the effect of residue C/nutrient ratio on P pools and N availability in wheat rhizosphere. The microcosms included an upper and a lower PVC core with one end of both cores covered by nylon mesh. Wheat was planted in the upper core. To the lower core, crop residues were added as a thin uniform layer on the top mesh. Treatments were control without residue or wheat growth, wheat growth without crop residue, barley straw without or with wheat growth, and barley faba bean residue without or with wheat growth. Sampling was carried out after 14 and 28 days in wheat rhizosphere alone, detritusphere of faba bean residue and barley straw, and in the rhizosphere/detritusphere interface. Mass loss of low C/P faba bean residue was greater than of high C/P barley straw; and mass loss was greater in the detritusphere alone than in the rhizosphere/detritusphere interface. Plant P concentration and P uptake were higher with faba bean residue than with straw and unamended wheat plants. With faba bean, most P pools and N availability, but not microbial biomass N and P, were lower in the rhizosphere/detritusphere interface than detritusphere alone. P pools were higher in detritusphere of faba bean residue than wheat rhizosphere alone. With straw, P pools and MBN were low and not affected by wheat roots. P pools and N availability in the wheat rhizosphere/detritusphere interface were influenced by residue type, and plant nutrient uptake reduced P pools and available N only with low carbon/nutrient faba bean residue. Keywords C/nutrient ratio . Crop-litter interface . P pools . Rhizosphere
1 Introduction The rhizosphere and detritusphere are two of the three hotspots of microbial activity in the soil (Ge et al. 2017; Kuzyakov and Blagodatskaya 2015). The rhizosphere is the soil within approximately 2 mm from the root surface (Dotaniya and Meena 2015). Compared with the bulk soil, it is characterised by high concentrations of easily available compounds that are released from plant roots (Mendes et al. 2013). The rhizosphere also supports a larger and more active microbial biomass than the bulk soil (Hoyle et al. 2008). Low molecular weight organic compounds, for example, organic acid anions, released by plant roots compete with phosphorus (P) sorbed to metal oxides (Bolan et al. 1994; Hinsinger 2001), and thereby increase the P in the soil solution for plant * Kehinde O. Erinle [email protected] 1
School of Agriculture, Food and Wine, The University of Adelaide, Adelaide, South Australia 5005, Australia
(and microbial) uptake. Nutrients released by exudates or microbes can be taken up by plant roots or immobilised into the microbial biomass, forming a nutrient depletion zone around the roots (Darrah
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