scholarly journals Biochar alters hydraulic conductivity and impacts nutrient leaching in two agricultural soils

SOIL ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 811-825
Author(s):  
Danielle L. Gelardi ◽  
Irfan H. Ainuddin ◽  
Devin A. Rippner ◽  
Janis E. Patiño ◽  
Majdi Abou Najm ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Agricultural Soils ◽  
Sandy Loam ◽  
Nutrient Retention ◽  
Production Method ◽  
Breakthrough Curves ◽  
Nutrient Leaching ◽  
Silt Loam ◽  
Primary Control ◽  
Almond Shell

Abstract. Biochar is purported to provide agricultural benefits when added to the soil, through changes in saturated hydraulic conductivity (Ksat) and increased nutrient retention through chemical or physical means. Despite increased interest and investigation, there remains uncertainty regarding the ability of biochar to deliver these agronomic benefits due to differences in biochar feedstock, production method, production temperature, and soil texture. In this project, a suite of experiments was carried out using biochars of diverse feedstocks and production temperatures, in order to determine the biochar parameters which may optimize agricultural benefits. Sorption experiments were performed with seven distinct biochars to determine sorption efficiencies for ammonium and nitrate. Only one biochar effectively retained nitrate, while all biochars bound ammonium. The three biochars with the highest binding capacities (produced from almond shell at 500 and 800 ∘C (AS500 and AS800) and softwood at 500 ∘C (SW500)) were chosen for column experiments. Biochars were amended to a sandy loam and a silt loam at 0 % and 2 % (w/w), and Ksat was measured. Biochars reduced Ksat in both soils by 64 %–80 %, with the exception of AS800, which increased Ksat by 98 % in the silt loam. Breakthrough curves for nitrate and ammonium, as well as leachate nutrient concentration, were also measured in the sandy loam columns. All biochars significantly decreased the quantity of ammonium in the leachate, by 22 % to 78 %, and slowed its movement through the soil profile. Ammonium retention was linked to high cation exchange capacity and a high oxygen-to-carbon ratio, indicating that the primary control of ammonium retention in biochar-amended soils is the chemical affinity between biochar surfaces and ammonium. Biochars had little to no effect on the timing of nitrate release, and only SW500 decreased total quantity, by 27 % to 36 %. The ability of biochar to retain nitrate may be linked to high micropore specific surface area, suggesting a physical entrapment rather than a chemical binding. Together, this work sheds new light on the combined chemical and physical means by which biochar may alter soils to impact nutrient leaching and hydraulic conductivity for agricultural production.

scholarly journals Biochar alters hydraulic conductivity and inhibits nutrient leaching in two agricultural soils

2021 ◽  
Author(s):  
Danielle L. Gelardi ◽  
Irfan Ainuddin ◽  
Devin A. Rippner ◽  
Majdi Abou Najm ◽  
Sanjai J. Parikh
Keyword(s):  
Hydraulic Conductivity ◽  
Sandy Loam ◽  
High Surface ◽  
High Surface Area ◽  
Nutrient Retention ◽  
Breakthrough Curves ◽  
Nutrient Leaching ◽  
Silt Loam ◽  
Primary Control ◽  
Almond Shell

Abstract. Biochar is purported to provide agricultural benefits when added to the soil, through changes in soil water hydraulic conductivity (Ksat), and increased nutrient retention through chemical or physical means. Despite increased interest and investigation, there remains uncertainty regarding the ability of biochar to deliver these agronomic benefits due to differences in biochar feedstock, production method, production temperature and soil texture. In this project, a suite of experiments was carried out using biochars of diverse feedstocks and production temperatures, in order to determine the biochar parameters which may optimize agricultural benefits. Sorption experiments were performed with seven distinct biochars to determine sorption efficiencies for ammonium and nitrate. Only one biochar effectively retained nitrate, while all biochars bound ammonium. The three biochars with the highest binding capacities (produced from almond shell at 500 and 800 °C (AS500 and AS800) and softwood at 500 °C (SW500)) were chosen for column experiments. Biochars were amended to a sandy loam and a silt loam at 0 and 2 % (w/w) and saturated hydraulic conductivity (Ksat) was measured. Biochars reduced Ksat in both soils by 64–80 %, with the exception of AS800, which increased Ksat by 98 % in the silt loam. Breakthrough curves for nitrate and ammonium, as well as leachate nutrient concentration, were also measured in the sandy loam columns. All biochars significantly decreased the quantity of ammonium in the leachate, by 22 to 78 %, and slowed its movement through the soil profile. Ammonium retention was linked to high cation exchange capacity and a high oxygen to carbon ratio, indicating that the primary control of ammonium retention in biochar-amended soils is the chemical affinity between biochar surfaces and ammonium. Biochars had little to no effect on the timing of nitrate release, and only SW500 decreased total quantity, by 27 to 36 %. The ability of biochar to retain nitrate may be linked to high surface area, suggesting a physical entrapment rather than a chemical binding. Together, this work sheds new light on the combined chemical and physical means by which biochar may alter soils to impact nutrient leaching and hydraulic conductivity for agricultural production.

The influence of biochar on nutrient leaching and hydraulic conductivity in two California soils

2021 ◽  
Author(s):  
Danielle L. Gelardi ◽  
Devin R. Rippner ◽  
Irfan Ainuddin ◽  
Andrew J. McElrone ◽  
Majdi Abou Najm ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Sandy Loam ◽  
Binding Capacity ◽  
High Surface ◽  
Nutrient Leaching ◽  
High Porosity ◽  
Silt Loam ◽  
Micro Computed Tomography ◽  
Almond Shell ◽  
Production Temperature

<p>The unique chemical and physical properties of biochars typically include low bulk density, high porosity, high surface area, reactive surface functional groups, and variable particle size distribution. These attributes make biochar a promising material for amendment to agricultural soils, as biochar may help improve soil water holding capacity, hydraulic conductivity (K<sub>sat</sub>), and nutrient retention through chemical or physical means. Despite increased interest and investigation, there remains uncertainty regarding the ability of biochar to alter soils to deliver these agronomic benefits, due to differences in biochar feedstock, production method, production temperature and soil texture. In this project, a suite of experiments was carried out using biochars of diverse feedstocks and production temperature, in order to determine the biochar parameters which may optimize agricultural benefits. Sorption experiments [SJP1] were performed with seven distinct, commercially available biochars to determine sorption efficiencies for ammonium and nitrate. Only one biochar effectively retained nitrate, while all biochars bound ammonium. The three biochars with the highest nitrate and/or ammonium binding capacity (produced from almond shell at 500 and 800 °C (AS500 and AS800) and softwood at 500 °C (SW500)), were chosen for a series of column experiments. These biochars were amended to a sandy loam and a silt loam at 0 and 2% (w/w) and saturated hydraulic conductivity (K<sub>sat</sub>) was measured. The biochars reduced K<sub>sat</sub> in both soils by 64-80%, with the exception of AS800, which increased K<sub>sat </sub>by 98% in the silt loam. Breakthrough curves for nitrate and ammonium, as well as concentrations of nutrients in the leachate, were also measured in the sandy loam columns.  Biochars significantly reduced the quantity of ammonium in the leachate, and significantly slowed its movement through the soil profile. Biochars had little to no effect on the timing and quantity of nitrate release. In this presentation, we present results from each experiment, and show images from our current work using x-ray micro-computed tomography on these soils and biochars to quantify porosity, pore size, and pore connectivity. Together, this work sheds new light on the chemical and physical means by which biochar alters soils to impact nutrient leaching and hydraulic conductivity.</p>

Solute movement through two unsaturated soils

Soil Research ◽  
1995 ◽  
Vol 33 (4) ◽  
pp. 585 ◽  
Author(s):  
GN Magesan ◽  
I Vogeler ◽  
DR Scotter ◽  
BE Clothier ◽  
RW Tillman
Keyword(s):  
Unsaturated Soils ◽  
Sandy Loam ◽  
Breakthrough Curves ◽  
Dead Volume ◽  
Silt Loam ◽  
Soil Columns ◽  
Concentration Data ◽  
Fine Sandy Loam ◽  
Solute Movement ◽  
Structured Soil

Simple and inexpensive apparatus is described for studying the solute movement during unsaturated water flow through intact soil columns. A preset pressure head is maintained at the top and bottom of the soil. The applied solution is easily changed, and there is negligible 'dead volume' both above and beneath the soil. Columns 37-150 mm long, carved from the A horizons of a well structured silt loam and a weakly structured fine sandy loam, were used in the apparatus. After the soil was preleached with calcium sulfate solution, solid potassium nitrate was applied, followed by a solution of potassium chloride. Nitrate and chloride concentrations in the effluent, and in the soil after leaching, were measured. With the imposed pressure heads of between -40 and -150 mm, flow rates ranged from 0 . 5 to 9 mm/h. The convection dispersion equation (CDE) with the appropriate boundary conditions was found to adequately describe the flow of chloride and nitrate in both soils. The outflow concentration data indicated all the soil water participated in the solute transport, and the chloride breakthrough curves scaled with column length as predicted by the CDE rather than by stochastic-convective theory. The dispersivity values for the well structured silt loam were 15 and 19 mm. The values for the weakly structured fine sandy loam were 68 and 27 mm. The dispersivity may be a useful structure index, as well as being the key parameter needed to describe solute movement. The resident concentration data indicated all the water in the well structured soil was mobile, but about 15% of the water in the weakly structured soil was relatively immobile.

Influence of soil texture on snowmelt infiltration into frozen soils

2002 ◽  
Vol 82 (1) ◽  
pp. 75-83 ◽  
Author(s):  
Litong Zhao ◽  
D. M. Gray ◽  
B. Toth
Keyword(s):  
Soil Texture ◽  
Agricultural Soils ◽  
Sandy Loam ◽  
Phase Changes ◽  
Silty Clay ◽  
Silt Loam ◽  
Clay Loam ◽  
Silty Clay Loam ◽  
Infiltration Process ◽  
Frozen Soils

This paper describes the influence of soil texture on snowmelt infiltration into frozen soils. Field data collected on frozen, unsaturated agricultural soils of the Canadian Prairies during snow ablation demonstrate: (a) poor association between the amount of infiltration of meltwater released by the seasonal snowcover and soil texture, and (b) small differences in cumulative amounts among soils of widely different textures. A physics-based numerical simulation of heat and mass transfers with phase changes in frozen soils is used to study the mechanics of the infiltration process in representative clay, silty clay loam, silt loam and sandy loam soils. The results of the simulations show that the differences among cumulative snowmelt infiltration into clay, silty clay loam and silt loam soils after 24 h of continuous infiltration are small. Infiltration into a lighter-textured sandy loam after 24 h was on average 23% higher than in the other three soils with most of the increase occurring in the first 5 h of the simulation. Key Words: Soil texture, snowmelt, infiltration, frozen soils

scholarly journals Movement of Dichlorvos in Farm Soils: Batch and Column Studies.

2020 ◽  
Author(s):  
Nahuel Bustos ◽  
Diego Grassi ◽  
Alicia Fernández Cirelli ◽  
Analia Iriel
Keyword(s):  
Environmental Fate ◽  
Agricultural Soils ◽  
Sandy Loam ◽  
High Mobility ◽  
Breakthrough Curves ◽  
Sandy Loam Soil ◽  
Column Studies ◽  
Desorption Process ◽  
Loam Soil ◽  
Adsorption Desorption

Abstract Soils are the principal environmental fate of pesticides in agricultural areas. Thus, the kinetics, extension, and strength of the adsorption process become critical. Dichlorvos (DDVP) is an organophosphorous pesticide that is used both in agriculture and livestock production. Sorption/desorption assays of DDVP in two agricultural soils (with different textural characteristics) from Pampa Plain (Argentina) were performed in both batch and column systems. From batch studies, kinetics and sorption/desorption equilibrium parameters were estimated. Our results showed that the maxima adsorption is reached after 30 h of time of contact and followed a pseudo-first-order rate. Adsorption/desorption data were well fitted to the Freundlich model obtaining high adsorption constants of 90 mg(1-1/n) mL(1/n) g-1 and 21 mg(1-1/n) mL(1/n) g-1 for the clay loam and sandy loam soil, respectively. The isotherms were non-linear in both cases and the desorption process was unfavourable. Also, positive hysteresis was present for the sandy loam soil. From column studies, breakthrough curves were used to evaluate the mobility of DDVP in the soils at 1, 10, and 50 mg L-1 of DDVP. Eluted profiles were asymmetrical as well they presented retardation effects that were in connection with the results in batch conditions. Non-equilibrium sorption was stated for the DDVP movement through columns. Thus, high mobility was observed for DDVP in both soils despite their textural differences.

Soil infiltration and hydraulic conductivity under long-term no-tillage and conventional tillage systems

1996 ◽  
Vol 76 (2) ◽  
pp. 143-152 ◽  
Author(s):  
R. H. Azooz ◽  
M. A. Arshad
Keyword(s):  
Hydraulic Conductivity ◽  
Sandy Loam ◽  
Field Capacity ◽  
Conventional Tillage ◽  
Silt Loam ◽  
Soil Infiltration ◽  
Tillage Systems ◽  
Infiltration Rates ◽  
Soil Pores

Long-term tillage practices may affect crop growth, in part by changing soil hydraulic properties. The hypothesis that long-term no-till (NT) and conventional tillage (CT) practices affect soil infiltration and hydraulic conductivity was evaluated on silt loam and sandy loam soils (both Gray Luvisols). Ponded soil infiltration, water content and marric potential were measured in the field during 1992 and 1993. In most cases, the ponded soil infiltration rates (i) were significantly lower (P ≤ 0.05) under the CT than under the NT for both soils. Total volume of soil pores with radii < 14 μm (micropores) were significantly greater in NT than in CT. Differences in volume of soil pores with radii > 14 μm (macropores) between CT and NT were not significant. For the initial soil moisture conditions ranging from dry to field capacity, the i values were greater by 0 24 to 3 01 cm h−1 in NT than in CT for the silt loam and by 3.30 to 4.13 cm h−1 for the sandy loam. Saturated hydraulic conductivity values were significantly greater in NT (range from 0.36 to 3.0 cm h−1) than in CT (range from 0.26 to 1.06 cm h−1). Unsaturated hydraulic conductivity increased more with increasing matric potential (less negative) in NT than in CT. Long-term NT practices kept soil pore structure and continuity undisturbed, which contributed to significantly greater hydraulic conductivity and infiltration rates in NT than in CT for both soils. Key words: Infiltration, hydraulic conductivity, macroporosity, microporosity, tillage systems

scholarly journals Effects of fresh and aged biochars from pyrolysis and hydrothermal carbonization on nutrient sorption in agricultural soils

2015 ◽  
Vol 2 (1) ◽  
pp. 29-65 ◽  
Author(s):  
M. Gronwald ◽  
A. Don ◽  
B. Tiemeyer ◽  
M. Helfrich
Keyword(s):  
Adsorption Capacity ◽  
Agricultural Soils ◽  
Sandy Loam ◽  
Nutrient Retention ◽  
Hydrothermal Carbonization ◽  
Field Application ◽  
Retention Capacity ◽  
Phosphate Retention ◽  
Ammonium Adsorption ◽  
Phosphate Leaching

Abstract. Leaching of nutrients from agricultural soils causes major environmental problems that may be reduced with biochar amendments to the soils. Biochars are characterised by a high adsorption capacity, i.e., they may retain nutrients such nitrate and ammonium. However, biochar properties strongly depend on feedstock and the production process. We investigated the nutrient retention capacity of biochars derived from pyrolysis (pyrochar) as well as from hydrothermal carbonization (hydrochar; produced at 200 and 250 °C) from three different feedstocks (digestates, Miscanthus, woodchips) mixed into different soil substrates (sandy loam and silty loam). Moreover, we investigated the influence of biochar degradation on its nutrient retention capacity using a seven-month in-situ field incubation of pyrochar and hydrochar. Pyrochars showed the highest ability to retain nitrate, ammonium and phosphate, with pyrochar from woodchips being particularly efficient in nitrate adsorption. Ammonium adsorption of pyrochars was controlled by the soil type of the soil-biochar mixture. We found some ammonium retention on sandy soils, but no pyrochar effect or even ammonium leaching from the loamy soil. The phosphate retention capacity of pyrochars strongly depended on the pyrochar feedstock with large phosphate leaching from digestate-derived pyrochar and some adsorption capacity from woodchip-derived pyrochar. Application of hydrochars to agricultural soils caused small, and often not significant, effects on nutrient retention. In contrast, some hydrochars did increase the leaching of nutrients compared to the non-amended control soil. We found a surprisingly rapid loss of the biochars' adsorption capacity after field application of the biochars. For all sites and for hydrochar and pyrochar, the adsorption capacity was reduced by 60–80% to less or no nitrate and ammonium adsorption. Thus, our results cast doubt on the efficiency of biochar applications to temperate zone soils to minimize nutrient losses via leaching.

scholarly journals Effects of fresh and aged chars from pyrolysis and hydrothermal carbonization on nutrient sorption in agricultural soils

SOIL ◽  
2015 ◽  
Vol 1 (1) ◽  
pp. 475-489 ◽  
Author(s):  
M. Gronwald ◽  
A. Don ◽  
B. Tiemeyer ◽  
M. Helfrich
Keyword(s):  
Adsorption Capacity ◽  
Agricultural Soils ◽  
Sandy Loam ◽  
Nutrient Retention ◽  
Hydrothermal Carbonization ◽  
Field Application ◽  
Retention Capacity ◽  
Phosphate Retention ◽  
Ammonium Adsorption ◽  
Phosphate Leaching

Abstract. Leaching of nutrients from agricultural soils causes major environmental problems that may be reduced with amendments of chars derived from pyrolysis (pyrochars) or hydrothermal carbonization (hydrochars). Chars are characterized by a high adsorption capacity – i.e. they may retain nutrients such as nitrate and ammonium. However, the physicochemical properties of the chars and hence their sorption capacity likely depend on feedstock and the production process. We investigated the nutrient retention capacity of pyrochars and hydrochars from three different feedstocks (digestates, Miscanthus, woodchips) mixed into different soil substrates (sandy loam and silty loam). Moreover, we investigated the influence of char degradation on its nutrient retention capacity using a 7-month in situ field incubation of pyrochar and hydrochar mixed into soils at three different field sites. Pyrochars showed the highest ability to retain nitrate, ammonium and phosphate, with pyrochar from woodchips being particularly efficient in nitrate adsorption. Ammonium adsorption of pyrochars was controlled by the soil type of the soil–char mixture. We found some ammonium retention on sandy soils, but no pyrochar effect or even ammonium leaching from the loamy soil. The phosphate retention capacity of pyrochars strongly depended on the pyrochar feedstock with large phosphate leaching from digestate-derived pyrochar and some adsorption capacity from woodchip-derived pyrochar. Application of hydrochars to agricultural soils caused small, and often not significant, effects on nutrient retention. In contrast, some hydrochars did increase the leaching of nutrients compared to the non-amended control soil. We found a surprisingly rapid loss of the chars' adsorption capacity after field application of the chars. For all sites and for hydrochar and pyrochar, the adsorption capacity was reduced by 60–80 % to less or no nitrate and ammonium adsorption. Thus, our results cast doubt on the efficiency of char applications to temperate zone soils to minimize nutrient losses via leaching.

Chloride and Lithium Transport in Large Arrays of Undisturbed Silt Loam and Sandy Loam Soil Columns

2004 ◽  
Vol 3 (1) ◽  
pp. 316
Author(s):  
M. Saleem Akhtar ◽  
Tammo S. Steenhuis ◽  
Brian K. Richards ◽  
Murray B. McBride
Keyword(s):  
Sandy Loam ◽  
Sandy Loam Soil ◽  
Silt Loam ◽  
Soil Columns ◽  
Lithium Transport ◽  
Loam Soil

Phosphorus transport in saturated slag columns: experiments and mathematical models

1996 ◽  
Vol 34 (1-2) ◽  
pp. 153-160 ◽  
Author(s):  
S. H. Lee ◽  
S. Vigneswaran ◽  
K. Bajracharya
Keyword(s):  
Mathematical Models ◽  
Sorption Capacity ◽  
Algal Blooms ◽  
Sandy Loam ◽  
Dynamic Condition ◽  
Water Environment ◽  
Breakthrough Curves ◽  
Column Experiments ◽  
Phosphorus Transport ◽  
Waste Products

Excessive phosphorus (P as orthophosphate) is one of the major pollutants in natural water that are responsible for algal blooms and eutrophication. P removal by slag is an attractive solution if the P sorption capacity of slag is significant. To design an efficient land treatment facility, basic information on the behaviour of P in the media-water environment is required. In this study, detailed column experiments were conducted to study the P transport under dynamic condition, and mathematical models were developed to describe this process. The column experiments conducted with dust and cake waste products (slag) from a steel industry as adsorbing indicated that they had higher sorption capacity of P than that of a sandy loam soil from North Sydney, Australia. P transport in the dust and cake columns exhibited characteristic S-shaped or curvilinear breakthrough curves. The simulated results from a dynamic physical nonequilibrium sorption model (DPNSM) and Freundlich isotherm constants satisfactorily matched the corresponding experimental breakthrough data. The mobility of P is restricted by the adsorbents and it is proportional to the sorption capacity of them.

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