Application of the PROFILE model to estimate potassium release from mineral weathering in Northern European agricultural soils

Roots and associated microbes generate acid-forming CO2 and organic acids and accelerate mineral weathering deep within Earth’s critical zone (CZ). At the Calhoun CZ Observatory in the USA’s Southern Piedmont, we tested the hypothesis that deforestation-induced deep root losses reduce root- and microbially-mediated weathering agents well below maximum root density (to 5 m), and impart land-use legacies even after ~70 y of forest regeneration. In forested plots, root density declined with depth to 200 cm; in cultivated plots, roots approached zero at depths >70 cm. Below 70 cm, root densities in old-growth forests averaged 2.1 times those in regenerating forests. Modeled root distributions suggest declines in density with depth were steepest in agricultural plots, and least severe in old-growth forests. Root densities influenced biogeochemical environments in multiple ways. Microbial community composition varied with land use from surface horizons to 500 cm; relative abundance of root-associated bacteria was greater in old-growth soils than in regenerating forests, particularly at 100–150 cm. At 500 cm in old-growth forests, salt-extractable organic C (EOC), an organic acid proxy, was 8.8 and 12.5 times that in regenerating forest and agricultural soils, respectively. The proportion of soil organic carbon comprised of EOC was greater in old-growth forests (20.0 ± 2.6%) compared to regenerating forests (2.1 ± 1.1) and agricultural soils (1.9 ± 0.9%). Between 20 and 500 cm, [EOC] increased more with root density in old-growth relative to regenerating forests. At 300 cm, in situ growing season [CO2] was significantly greater in old-growth forests relative to regenerating forests and cultivated plots; at 300 and 500 cm, cultivated soil [CO2] was significantly lower than in forests. Microbially-respired δ13C-CO2 suggests that microbes may rely partially on crop residue even after ~70 y of forest regeneration. We assert that forest conversion to frequently disturbed ecosystems limits deep roots and reduces biotic generation of downward-propagating weathering agents.

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Soil weathering rates in 21 catchments of the Canadian Shield

Hydrology and Earth System Sciences ◽

10.5194/hess-16-685-2012 ◽

2012 ◽

Vol 16 (3) ◽

pp. 685-697 ◽

Cited By ~ 18

Author(s):

D. Houle ◽

P. Lamoureux ◽

N. Bélanger ◽

M. Bouchard ◽

C. Gagnon ◽

...

Keyword(s):

Base Cations ◽

Base Cation ◽

High Reactivity ◽

Mineral Weathering ◽

Forest Growth ◽

Canadian Shield ◽

Geochemical Model ◽

Soil Weathering ◽

Weathering Rates ◽

Profile Model

Abstract. Soil mineral weathering represents an essential source of nutrient base cation (Ca, Mg and K) for forest growth in addition to provide a buffering power against precipitation acidity for soils and surface waters. Weathering rates of base cations were obtained for 21 catchments located within the temperate and the boreal forest of the Canadian Shield with the geochemical model PROFILE. Weathering rates ranged from 0.58 to 4.46 kmolc ha−1 yr−1 and their spatial variation within the studied area was mostly in agreement with spatial variations in soil mineralogy. Weathering rates of Ca and Mg were significantly correlated (r = 0.80 and 0.64) with their respective lake concentrations. Weathering rates of K and Na did not correlate with lake concentrations of K and Na. The modeled weathering rates for each catchment were also compared with estimations of net catchment exportations. The result show that modeled weathering rates of Ca were not significantly different than the net catchment exportations while modeled weathering rates of Mg were higher by 51%. Larger differences were observed for K and Na weathering rates that were significantly different than net catchment exportations being 6.9 and 2.2 times higher than net exportations, respectively. The results for K were expected given its high reactivity with biotic compartments and suggest that most of the K produced by weathering reactions was retained within soil catchments and/or above ground biomass. This explanation does not apply to Na, however, which is a conservative element in forest ecosystems because of the insignificant needs of Na for soil microorganisms and above ground vegetations. It raises concern about the liability of the PROFILE model to provide reliable values of Na weathering rates. Overall, we concluded that the PROFILE model is powerful enough to reproduce spatial geographical gradients in weathering rates for relatively large areas as well as adequately predict absolute weathering rates values for the sum of base cations, Ca and Mg.

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A critical evaluation of the use of the profile model in calculating mineral weathering rates

Water Air & Soil Pollution ◽

10.1007/bf02128651 ◽

1997 ◽

Vol 98 (1-2) ◽

pp. 79-104 ◽

Cited By ~ 26

Author(s):

Mark E. Hodson ◽

Simon J. Langan ◽

M. Jeff Wilson

Keyword(s):

Critical Evaluation ◽

Mineral Weathering ◽

Weathering Rates ◽

Profile Model

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Soil weathering rates in 21 catchments of the Canadian Shield

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-8-5743-2011 ◽

2011 ◽

Vol 8 (3) ◽

pp. 5743-5768 ◽

Cited By ~ 1

Author(s):

D. Houle ◽

P. Lamoureux ◽

N. Bélanger ◽

M. Bouchard ◽

C. Gagnon ◽

...

Keyword(s):

Base Cations ◽

Base Cation ◽

High Reactivity ◽

Mineral Weathering ◽

Forest Growth ◽

Canadian Shield ◽

Geochemical Model ◽

Soil Weathering ◽

Weathering Rates ◽

Profile Model

Abstract. Soil mineral weathering represents an essential source of nutrient base cation (Ca, Mg and K) for forest growth in addition to provide a buffering power against precipitation acidity for soils and surface waters. Weathering rates of base cations were obtained for 21 catchments located within the temperate and the boreal forest of the Canadian Shield with the geochemical model PROFILE. Weathering rates ranged from 0.58 to 4.46 kmolc ha−1 yr−1 and their spatial variation within the studied area was mostly in agreement with spatial variations in soil mineralogy. Weathering rates of Ca and Mg were significantly correlated (r = 0.80 and 0.64) with their respective lake concentrations. Weathering rates of K and Na did not correlate with lake concentrations of K and Na. The modeled weathering rates for each catchment were also compared with estimations of net catchment exportations. The result show that modeled weathering rates of Ca were not significantly different than the net catchment exportations while modeled weathering rates of Mg were higher by 51 %. Larger differences were observed for K and Na weathering rates that were significantly different than net catchment exportations being 6.9 and 2.2 times higher than net exportations, respectively. The results for K were expected given its high reactivity with biotic compartments and suggest that most of the K produced by weathering reactions was retained within soil catchments and/or above ground biomass. This explanation does not apply to Na, however, which is a conservative element in forest ecosystems because of the insignificant needs of Na for soil microorganisms and above ground vegetations. It raises concern about the liability of the PROFILE model to provide reliable values of Na weathering rates. Overall, we concluded that the PROFILE model is powerful enough to reproduce spatial geographical gradients in weathering rates for relatively large areas as well as adequately predict absolute weathering rates values for the sum of base cations, Ca and Mg.

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Bio-Organic Mineral Fertilizer for Sustainable Agriculture: Current Trends and Future Perspectives

Minerals ◽

10.3390/min11121336 ◽

2021 ◽

Vol 11 (12) ◽

pp. 1336

Author(s):

Shameer Syed ◽

Xingxing Wang ◽

Tollamadugu N.V.K.V. Prasad ◽

Bin Lian

Keyword(s):

Microbial Community ◽

Plant Growth ◽

Soil Fertility ◽

Agricultural Soils ◽

Mineral Fertilizer ◽

Mineral Weathering ◽

Mineral Fertilizers ◽

Microbial Culture ◽

Organic Mineral ◽

Synthetic Fertilizers

Chemical (synthetic) fertilizers used indiscriminately for improved production pose a major threat to long-term soil fertility, the soil environment, and its components. The soil microbial community, however, plays a major and important role in fostering soil health and plant growth. While the use of synthetic fertilizers has a profound impact on plant growth, it also significantly alters the makeup of the microbial community towards a detrimental low, especially N and P fertilizers. Sustainable farming practices can reduce the depletion of natural resources and maintain both productivity and soil fertility. The use of minerals that contain fertilizer nutrients in their native state is a very promising approach to reducing emissions associated with the processing chemical industries. Organic material from natural sources (food waste, manure from livestock, agricultural biomass, etc.) acts as a source of microbial culture and encourages the release of nutrients into the soil during mineral weathering. The combination of nutrient-bearing minerals and their biological weathering agents together with organic matter has the potential to remediate, restore, and sustain depleted agricultural soils. Therefore, in this review, we emphasize the significance of sustaining agricultural productivity and microbial diversity in the rhizosphere, the two vital aspects of modern agricultural systems, through bio-organic mineral fertilizers.

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