The performance of DGT versus conventional soil phosphorus tests in tropical soils—maize and rice responses to P application

Six, Laetitia; Smolders, Erik; Merckx, Roel

doi:10.1007/s11104-012-1375-4

Cited by 87 publications

(72 citation statements)

References 64 publications

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“…Davidson et al 2000, Zhang et al 2002, so that one would expect uptake to be determined by physical availability. Recent work on the correlation of P uptake in plants and DGT have mostly been from tropical soils with high P sorption capacity (Mason et al 2010, Six et al 2013, where it can also be expected that physical availability determined uptake. Soils in temperate regions generally have lower sorption capacity than tropical soils, and it can therefore be expected that DGT will have somewhat lower predictive ability in those soils.…”

Section: (22) Discussionmentioning

confidence: 99%

“…A new method based physical diffusion, diffusive gradient in thin films (DGT) was originally developed to measure bioavailability of metals in natural waters (Davidson and Zhang 1994), and has also been developed to measure bioavailability in soil solution , Zhang et al 2001. It has recently also been developed for P bioavailability in soils (Zhang et al 2013) and it appears to predict plant available P better than any other single method (Mason et al 2010, Tandy et al 2011, Six et al 2013.…”

Section: Introductionmentioning

confidence: 99%

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Phosphorus availability in residues as fertilizers in organic agriculture

Føreid

2017

AFSci

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Phosphorus (P) should be recycled from organic wastes as much as possible, and input is needed in stockless organic agriculture. Seven organic residues were assessed and compared them to mineral P fertilizer and rock phosphate as fertilizer for barley. P availability in the mixtures and residual P availability were also assessed by diffusive gradients in thin films (DGT). The best availability was found in digested liquid manure followed by wood ash, fish sludge, composted solid manure and composted food waste. Meat and bone meal, the commercially available product Ladybug plus and rock phosphate had low P availability at the same level as no P. Only wood ash had significant P available for the next crop. The pH level of the soil did not affect P availability for any of the P sources. DGT predicted P availability moderately well, as it measures P supply over a short period without any biological factors.

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Section: (22) Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Phosphorus availability in residues as fertilizers in organic agriculture

Føreid

2017

AFSci

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“…It is unknown how effects of flooding on soil labile P and on

{normalH}_{2} {PO}_{4}^{-}

sorption ( 33 P recovery) translate to soil P bioavailability for flooded rice, that is, to what extent flooded rice can benefit from released P. As far as we are aware, no data are available to state which chemical index of soil P availability explains P uptake in flooded rice in highly weathered soils. Our recent pot trial study with rainfed rice in weathered soil revealed that the resin P (AEM‐P) required in soil for 80% of maximal yield was 19 mg P/kg soil (Six et al ., ). Tables and combined show that flooding increased AEM‐P in unfertilized soil by a maximum of 11 mg P/kg soil (details not shown) to 13 mg P/kg soil.…”

Section: Discussionmentioning

confidence: 99%

Soil flooding and rice straw addition can increase isotopic exchangeable phosphorus in P‐deficient tropical soils

Rakotoson

Amery

Rabeharisoa

et al. 2014

Soil Use and Management

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Soil flooding increases phosphorus (P) availability due to reductive dissolution of P‐bearing Fe(III) minerals. It is, however, unclear whether such processes also act in P‐deficient soils of the tropics that have large Fe/P ratios (dithionite‐ and oxalate‐extractable P and Fe). The objective was to identify the extent of P release induced by flooding in such soils and the soil characteristics involved. Six topsoils (0.4–5% Fe) from rice fields in Madagascar were incubated aerobically and anaerobically for 66 days amended with factorial combinations of normalH2PO4− (0, 50 mg P/kg); half of the flooded soils were also amended with 1 g rice straw/kg prior to flooding to stimulate soil oxygen depletion. The release of P after flooding was measured at day 40 with 33P isotopic exchange, which detects both changes of labile P (exchangeable P) and changes in P solubility. Flooding increased labile P concentration in soil compared with aerobic soils by 1.4–60 mg P/kg, effects being significant in 6 of the 12 soil samples. Rice straw addition further increased the labile P in 5 of the 12 flooded soil samples by 2–27 mg P/kg. The release of labile P by flooding increased with soil oxalate‐extractable P concentration. Flooding combined with rice straw addition can increase the labile P in soil, even in soils with large amount of Fe; however, this release in unfertilized soils is likely insufficient for optimal nutrition of rice plants when evaluated against critical values for P solubility.

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“…Standard procedures to assess P availability in soils are based on one-step or fractionated batch experiments with various extractants (Ziadi et al, 2013). However, the results are difficult to relate directly to plant availability (Sibbesen, 1983;Six et al, 2013). Deepest insights in the dynamic aspects of P mobilization and immobilization in soils have been obtained with isotopic dilution techniques (Frossard et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

“…Deepest insights in the dynamic aspects of P mobilization and immobilization in soils have been obtained with isotopic dilution techniques (Frossard et al, 2011). It has been shown that batch extracts mobilize P from pools not directly available to plants (Mason et al, 2013;Six et al, 2013). More comparable to the root's approach is to strip phosphate from the solid phase by lowering the soil-solution concentration, which can be achieved by establishing an infinite diffusional sink (Frossard et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

Assessment of diffusive phosphate supply in soils by microdialysis

Demand

Schack‐Kirchner

Lang

2017

J. Plant Nutr. Soil Sci.

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Standard procedures to assess P availability in soils are based on batch experiments with various extractants. However, in most soils P nutrition is less limited by bulk stocks but by strong adsorption and transport limitation. The basic principle of root‐phosphate uptake is to strip phosphate locally from the solid phase by forming a radial depletion zone in the soil solution, optionally enhanced by release of mobilizing substances. Microdialysis (MD), a well‐established method in pharmacokinetics, is capable to mimic important characteristics of P root uptake. The sampling is by diffusional exchange through a semipermeable membrane covering the probes with their sub‐mm tubular structure. Additionally, the direct environment of the probe can be chemically modified by adding, e.g., carboxylates to the perfusate. This study is the first approach to test the applicability of MD in assessing plant available phosphate in soils and to develop a framework for its appropriate use.We used MD in stirred solutions to quantify the effect of pumping rate, concomitant ions, and pH value on phosphate recovery. Furthermore, we measured phosphate yield of top‐soil material from a beech forest, a non‐fertilized grassland, and from a fertilized corn field. Three perfusates have been used based on a 1 mM KNO3 solution: pure (1), with 0.1 mM citric acid (2), and with 1 mM citric acid (3). Additionally, a radial diffusion model has been parametrized for the stirred solutions and the beech forest soil.Results from the tests in stirred solutions were in good agreement with reported observations obtained for other ionic species. This shows the principal suitability of the experimental setup for phosphate tests. We observed a significant dependency of phosphate uptake into the MD probes on dialysate pumping rate and on ionic strength of the outside solution. In the soils, we observed uptake rates of the probes between 1.5 × 10−15 and 6.7 × 10−14 mol s−1 cm−1 in case of no citrate addition. Surprisingly, median uptake rates were mostly independent of the bulk soil stocks, but the P‐fertilized soil revealed a strong tailing towards higher values. This indicates the occurrence of hot P spots in soils. Citrate addition increased P yields only in the higher concentration but not in the forest soil. The order of magnitude of MD uptake rates from the soil samples matched root‐length related uptake rates from other studies. The micro‐radial citrate release in MD reflects the processes controlling phosphate mobilization in the rhizosphere better than measurements based on “flooding” of soil samples with citric acid in batch experiments. Important challenges in MD with phosphate are small volumes of dialysate with extremely low concentrations and a high variability of results due to soil heterogeneity and between‐probe variability. We conclude that MD is a promising tool to complement existing P‐analytical procedures, especially when spatial aspects or the release of mobilizing substances are in focus.

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The performance of DGT versus conventional soil phosphorus tests in tropical soils—maize and rice responses to P application

Cited by 87 publications

References 64 publications

Phosphorus availability in residues as fertilizers in organic agriculture

Phosphorus availability in residues as fertilizers in organic agriculture

Soil flooding and rice straw addition can increase isotopic exchangeable phosphorus in P‐deficient tropical soils

Assessment of diffusive phosphate supply in soils by microdialysis

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