Contrasting pH buffering patterns in neutral-alkaline soils along a 3600 km transect in northern China

Luo, Wentao; Nelson, Paul N.; Li, Mai‐He; Cai, Jiangping; Zhang, Y. Y.; Zhang, Y. G.; Yang, Shan; Wang, R. Z.; Wang, Z. W.; Wu, Yunna; Han, Xingguo; Jiang, Yong

doi:10.5194/bg-12-7047-2015

Cited by 50 publications

(34 citation statements)

References 49 publications

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“…The soil and water mixture was shaken end-over-end for 1 h, and the pH of supernatant was measured after centrifuging at 492 g for 10 min. Soil CaCO 3 content was determined by measuring the volume of CO 2 released from 2 g of air-dried soil (< 0.150 mm), followed by the addition of 8 mL of hydrochloric acid (HCl, 3 mol L −1 ) at room temperature (Luo et al 2015). The soil organic matter (SOM) was determined by dichromate oxidation and titration with ferrous ammonium sulfate (Walkley and Black 1934).…”

Section: Sampling and Analysesmentioning

confidence: 99%

Impacts of fertilization practices on pH and the pH buffering capacity of calcareous soil

Zhang

Wang

et al. 2016

Soil Science and Plant Nutrition

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Modern intensive agricultural practices, particularly the use of nitrogen fertilizers, have accelerated soil acidification on a global scale. The soil pH buffering capacity (pHBC) is often used to quantify the soil acidification rate. Calcareous soils have relatively higher pH and pHBC, reflecting the presence of carbonate minerals; however, the impact of long-term fertilization treatment on pH and pHBC is poorly understood for calcareous soils. Here, calcareous soil samples (0-20 cm) were collected from fields receiving six different fertilization treatments for 22 years: control (CK, unfertilized but planted); nitrogen (N); nitrogen and phosphorus (NP); nitrogen, phosphorus and potassium (NPK); combined manure and NPK (NPKM); and combined corn-stover and NPK (NPKS). Both pH and pHBC significantly decreased for all treatments relative to CK. NPKS treatment had the lowest soil pH. Compared with CK, the soil pHBC decreased 5.7 to 17.3% under different treatments. The calcium carbonate (CaCO 3) content was significantly reduced by fertilization treatments, with a maximum decrease under the NPKS treatment. Structural equation model (SEM) analysis revealed that calcium carbonate and soil organic matter (SOM) made important contributions to effective cation exchangeable capacity (ECEC). Soil pHBC was directly controlled by ECEC, while CaCO 3 and SOM indirectly contributed to the pHBC through ECEC. These results indicated that NPKS treatment induces more severe soil acidification, reflecting the higher H + input and lower pHBC under this treatment.

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Section: Sampling and Analysesmentioning

confidence: 99%

Impacts of fertilization practices on pH and the pH buffering capacity of calcareous soil

Zhang

Wang

et al. 2016

Soil Science and Plant Nutrition

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“…It should be emphasized that the pH buffering systems in acidic and alkaline soils are different, and Manuscript to be reviewed two main pH buffering mechanisms in soils have been proposed, namely buffering by carbonates in alkaline soils with high pH (> 7.5) and by aluminum compounds in acidic soils with low pH (< 4.5) (Bowman et al 2008;Lieb et al 2011). Under our research regions with higher temperature and lower precipitation, in which potential evapotranspiration greatly exceeds precipitation, carbonate tends to accumulate and thereby enhance soil pH buffering capacity in the surface soil layer (Luo et al 2015), whereas in regions with higher precipitation, leaching processes prevent the accumulation of carbonate and change the soil acidification rates. It is also interesting to note from this study that significant negative quadratic relationships were observed between soil pH and C s / C r ratios and litter mass loss although both were relatively weak, and the respective vertex coordinates of the quadratic function were 8.37 and 8.43 for soil pH, respectively.…”

Section: Effect Of Soil Ph On Carbon Storage Capacity Of Soil Aggregatesmentioning

confidence: 93%

“…Precipitation primarily falls during the growing season (June-August), which coincides with the highest temperatures (Yang et al 2019a). The site has a calcic-orthic Aridisol (highly alkaline) soil with a loamy-sand texture, and the carbonate content is about 12 g kg -1 (Luo et al 2015). The sand: silt: clay ratio is about 40:10:1, and the cation exchange capacity is around 20 cmol (+) kg -1 (Cai et al 2017;Li et al 2019).…”

Section: Materials Collectionmentioning

confidence: 99%

Peer Review #2 of "Soil aggregates indirectly influence litter carbon storage and release through soil pH in the highly alkaline soils of north China (v0.1)"

2019

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Background. Soil aggregate-size classes, structural units of soil, are the important factors regulating soil organic carbon (SOC) turnover. However, the processes of litter C mineralization and storage in different aggregates-size classes are poorly understood, especially in the highly alkaline soils of north China. Here we ask how four different aggregate sizes influence rates of C release (Cr) and SOC storage (Cs) in response to three types of plant litter added to an un-grazed natural grassland. Methods. Highly alkaline soil samples were separated into four dry aggregate classes of different sizes (2-4, 1-2, 0.25-1 and < 0.25 mm). Three types of dry dead plant litter (leaf, stem and all standing dead aboveground litter) of Leymus chinensis were added to each of the four aggregate class samples. Litter mass loss rate, Cr, and Cs were measured periodically during the 56-day incubation. Results. The results showed that the mass loss in 1-2 mm aggregates was significantly greater than that in other size classes of soil aggregates on both day 28 and day 56. Macro-aggregates (1-2 mm) had the highest Cr of all treatments, whereas 0.25-1 mm aggregates had the lowest. In addition, a significant negative relationship was found between Cs / Cr and soil pH. After incubation for 28 and 56 days, the Cs was also highest in the 1-2 mm aggregates, which implied that the macro-aggregates had not only a higher CO2 release capacity, but also a greater litter C storage capacity than the micro-aggregates in the highly alkaline soils of north China.

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“…Existing knowledge demonstrates that multiple processes could be involved in the processes of soil acid buffering, with specific mechanisms working under various pH conditions [13]. For the carbonate-containing soils of high pH, for example, acid neutralization by the dissolution reaction of carbonate may play a predominant role to produce the soil acid-buffering capacity, while the soil cation exchange capacity (CEC) could be more important in the noncarbonate soils [15]. In several types of strongly acidic soils that distribute widely across those low latitude regions of the earth, however, the hydrolysis reaction of aluminum bound to organic materials could be the major source of soil acid-buffering capacity [16].…”

Section: Introductionmentioning

confidence: 99%

Soil pH Responses to Simulated Acid Rain Leaching in Three Agricultural Soils

et al. 2019

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Soil has the nature of acidity and alkalinity, mostly indicated by soil pH that could greatly affect soil ecological processes and functions. With exogenous inputs of acidic materials (such as acid rain), soils may more or less resist to maintain their pH levels within specific thresholds by various buffering processes. It has been well established that soil properties such as cation exchange capacity (CEC), soil organic matter (SOM), and clay content play important roles in mitigating the effects of acid inputs, but the factors varied across soils. This microcosm experiment was conducted to investigate changes in the soil pH and quantitatively estimate the critical pH threshold of simulated acid rain for three highly weathered soils (red soil, lateritic red soil, and latosol) that are typical soil types widely distributed across the world’s subtropical and tropical climatic zones, as well as important influential factors, after continuously adding different levels of simulated acid rain on the surface of soil cores. The results showed that the change in the soil pH was not significantly different among the three soils, although it was exponentially related to soil CEC and clay content. Resultantly, the latosol that had high soil CEC and clay content was more resistant to simulated acid rain, especially when relatively weak simulated acid rain treatments were applied. The lateritic red soil that contained the lowest soil CEC and clay content showed the greatest decline in the soil pH under the strongest simulated acid rain treatment of pH being 2.5. Furthermore, we estimated the critical pH threshold of simulated acid rain for the three soils and observed that it was considerably different among the soils. Surprisingly, the pH threshold of simulated acid rain was also positively related to the soil CEC and clay content, therefore making the highest pH threshold in the latosol. Our results imply that soil CEC and clay content may play critical roles in the soil acid-buffering processes from two aspects; it could not only contribute to the soil acid-buffering capacity, but also affect the threshold of acidity of acid rain below which abrupt soil acidification may occur.

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Contrasting pH buffering patterns in neutral-alkaline soils along a 3600 km transect in northern China

Cited by 50 publications

References 49 publications

Impacts of fertilization practices on pH and the pH buffering capacity of calcareous soil

Impacts of fertilization practices on pH and the pH buffering capacity of calcareous soil

Peer Review #2 of "Soil aggregates indirectly influence litter carbon storage and release through soil pH in the highly alkaline soils of north China (v0.1)"

Soil pH Responses to Simulated Acid Rain Leaching in Three Agricultural Soils

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