Depth sequence distribution of water extractable colloidal phosphorus and its phosphorus speciation in intensively managed agricultural soils

Long-term row crop agricultural production has dramatically reduced the pool of soil organic carbon. The implementation of cover crops in Midwestern agroecosystems is primarily to reduce losses of nitrogenous fertilizers, but has also been shown to restore soil carbon stocks over time. If labile carbon within agricultural soils could be increased, it could improve soil health, and if mobilized into subsurface drainage, it may positively impact watershed biogeochemistry. We tested for potential differences in water-extractable organic carbon (WEOC) at two different soil profiles (0-5 cm and 5-20 cm) between plots planted with cereal rye/daikon radish (cover crop), corn, and zero control (no vegetation) within the Illinois State University Research and Teaching Farm. We also tested for potential differences in denitrification within the upper soil profile throughout the growing year. We modeled excitation–emission matrices from soil cores through parallel factor analysis. We found no difference in WEOC concentrations between each crop treatment ( P = 0.2850), but concentrations of WEOC were significantly lower in the 5-20 cm profile than that in the upper (0-5 cm) profile ( P = 0.0033). There was a significant increase in WEOC after each treatment in samples after cover crop termination. The parallel factor analysis model found humic and fulvic acids to be the dominant fractions of WEOC in all soils tested. Humic and fulvic acids accounted for ~70% and 30% of model variation. Denitrification rates did not differ across treatments ( P = 0.3520), which is likely attributed to soil WEOC being in limiting quantities and in primarily recalcitrant fractions. After three years, cover crops do not appear to alter soil WEOC quantity and type. Restoring the availability of carbon within agricultural soils will not be a short-term fix, and fields will likely be a net carbon sink, contributing minimal labile carbon to receiving waterways.

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Comparison of surface properties of synthetic and soil struvite

Canadian Journal of Soil Science ◽

10.4141/cjss2013-099 ◽

2014 ◽

Vol 94 (2) ◽

pp. 169-176

Author(s):

S. M. Y. Baugé ◽

L. M. (Les) Lavkulich ◽

J. E. Wilson ◽

H. E. Schreier

Keyword(s):

Surface Layer ◽

Surface Properties ◽

Agricultural Soils ◽

Analytical Techniques ◽

Additional Species ◽

X Ray ◽

Phosphate Mineral ◽

Intensively Managed ◽

Secondary Ion ◽

Phosphorus Chemistry

Baugé, S. M. Y., Lavkulich, L. M., Wilson, J. E. and Schreier, H. E. 2014. Comparison of surface properties of synthetic and soil struvite. Can. J. Soil Sci. 94: 169–176. X-ray, Raman and nuclear magnetic resonance (NMR) analyses of intensively managed agricultural soils in southwestern British Columbia reported the presence of the Mg-phosphate mineral, struvite. Soils are heterogeneous, thus analytical techniques based on single minerals require calibration in order to provide reliable results. A synthetic struvite was used to compare the properties of the soil phosphate with struvite. The results confirmed the presence of struvite and possibly additional species of Mg. Time of flight–secondary ion mass spectroscopy (TOF-SIMS) revealed that the surface of struvite, to 2nm depth, is dominated by Mg with other cations, notably Fe and NH4 that were measured in minor amounts and were associated with the Mg rich surface layer. The results suggest that P is located within the struvite structure. Chemical reactions of struvite and phosphorus chemistry in these soils appear to be governed by the Mg surface layer.

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Exchangeable cation effects on hot water extractable carbon and nitrogen in agricultural soils

Soil Research ◽

10.1071/sr19222 ◽

2020 ◽

Vol 58 (4) ◽

pp. 356

Author(s):

Denis Curtin ◽

Weiwen Qiu ◽

Michelle E. Peterson ◽

Mike H. Beare ◽

Craig R. Anderson ◽

...

Keyword(s):

Organic Matter ◽

Agricultural Soils ◽

Aromatic Amino Acids ◽

Hot Water ◽

Organic N ◽

Exchangeable Cation ◽

Sodic Soils ◽

Desorption Process ◽

Rate Of Increase ◽

Water Extractable

Hot water is believed to extract bio-available soil organic matter (SOM), including organic compounds from the biomass of soil microbes. The role of soil physico-chemical factors in relation to extractability of SOM in hot water is not well understood. We evaluated the influence of exchangeable sodium (Na) on the quantity and quality of organic matter extracted in hot water from soils with a range of total and extractable C (total C 19–60 g kg–1; hot water extractable C (HWC) 659–3292 mg kg–1). The soils were pre-treated with different rates of Na (0–156 cmolc kg–1, as NaCl) to establish a range of exchangeable Na percentages (ESP), and then extracted with hot water (80°C) for 16 h. Hot water extractable C increased linearly as ESP increased, but the rate of increase differed between soils (the increase in HWC per unit increase in ESP ranged within 19–71 mg kg–1). At ESP 15, a threshold used to separate sodic and non-sodic soils, HWC was 30–60% greater than that measured without added Na. Ultraviolet absorbance (260 nm) data indicated that aromatic organic matter was preferentially released following Na pre-treatment. The proportion of HWC in phenolic form was generally little affected by Na treatment but there was a consistent increase in protein in response to Na (hot water extractable organic N in protein form increased from an average of 5.5 ± 2.2% without added Na to 11.0 ± 3.6% at the highest Na rate). The Na-induced increases in UV absorbance may be largely attributable to release of proteins containing aromatic amino acids (tryptophan and tyrosine). Our results suggest that organic matter desorbed from mineral surfaces may be an important contributor to hot water extractable C and N, and factors that affect the adsorption–desorption process may significantly influence organic matter extractability in hot water.

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Dynamics of ammonia oxidizers in response to different fertilization inputs in intensively managed agricultural soils

Applied Soil Ecology ◽

10.1016/j.apsoil.2020.103729 ◽

2021 ◽

Vol 157 ◽

pp. 103729

Author(s):

Xia Li ◽

Yanwei Wang ◽

Yunlong Zhang ◽

Ming Lang ◽

Peter Christie ◽

...

Keyword(s):

Agricultural Soils ◽

Ammonia Oxidizers ◽

Intensively Managed

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Changes on water‐extractable organic matter in tropical forest and agricultural soils as detected by DRIFT spectroscopy technique

Land Degradation and Development ◽

10.1002/ldr.4076 ◽

2021 ◽

Author(s):

Silézio F. Silva ◽

Riccardo Spaccini ◽

Pierluigi Mazzei ◽

Carlos Eduardo Rezende ◽

Luciano P. Canellas

Keyword(s):

Organic Matter ◽

Tropical Forest ◽

Agricultural Soils ◽

Spectroscopy Technique ◽

Drift Spectroscopy ◽

Extractable Organic Matter ◽

Water Extractable

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Potential of Mehlich 3 method for extracting plant available sulfur in the Czech agricultural soils

Plant Soil and Environment ◽

10.17221/372/2018-pse ◽

2018 ◽

Vol 64 (No. 9) ◽

pp. 455-462

Author(s):

Kulhánek Martin ◽

Černý Jindřich ◽

Balík Jiří ◽

Sedlář Ondřej ◽

Suran Pavel

Keyword(s):

Regression Analysis ◽

Agricultural Soils ◽

Soil Samples ◽

The Other ◽

Organic S ◽

Correlation And Regression Analysis ◽

Close Relationship ◽

Good Potential ◽

Preliminary Study ◽

Water Extractable

Mehlich 3 is an extractant used worldwide for extracting bioavailable nutrients in soils; however, its extraction abilities for sulfur (S) are still not well described. The aim of this preliminary study was to compare the results of Mehlich 3 determined soil S fraction (SM3) with the results of sulfur fractionation, mainly focusing on bioavailable S (Sav – sum of water-extractable (Sw) and adsorbed (Sads) sulfur). Air dried soil samples from commonly used agricultural soils were chosen for the analyses. The following S fractions were determined: (i) Sw; (ii) Sads; (iii) Sav; (iv) 1 mol/L HCl extractable (SHCl); (v) estersulfate (Ses); (vi) organic (Sorg) and (vii) total (Stot). The median value of SM3 (18.3 mg/kg) was similar to Sav (17.9 mg/kg). From the correlation and regression analysis it is clear that SM3 results are in close relationship with Sav form. On the other hand, the relationships between SM3 and organic S (including SHCl) were very weak. Based on the obtained results it can be concluded that Mehlich 3 method has a good potential to determine bioavailable sulfur in commonly used agricultural soils. However, especially the plant response should be further studied to confirm this theory.

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