scholarly journals Soil organic carbon and iron oxides affects soil aggregate stability under straw returning and potassium fertilizer in a rice--rape cropping system

Author(s):  
Bin Xue ◽  
Li Huang ◽  
Jianwei Lu ◽  
Xiaokun Li ◽  
Ruili Gao ◽  
...  

Soil organic carbon (SOC) and iron (Fe) oxides are known to affect the formation and stability of soil aggregates. However, the effects of SOC and Fe oxides on soil aggregates stability under straw returning and potassium (K) fertilizer application in paddy–upland rotation systems are less well-studied. This study primarily investigated soil aggregates dynamics and their stability indices (mean weight diameter, MWD; geometric mean diameter, GMD), and soil binders (SOC and iron oxides) after rice and rape harvests under four treatments: F1,mineral nitrogen (N) and phosphorus (P) fertilizer; F2, mineral NPK fertilizer; F3, mineral NP fertilizer with straw returning; F4, mineral NPK fertilizer with straw returning in rice–rape cropping system. Straw returning treatments (F3 and F4) significantly (P <0.05) increased MWD and GMD, but the effect of K is not obvious. The soil aggregates stability was higher after the rape harvest than rice harvest, but SOC content was the opposite. Straw input can increase the contents of SOC, alkane-C and aromatic-C concentrations, especially in >0.25 mm aggregates. Long-term straw incorporation significantly increased the amorphous (Feo) and complex iron oxides (Fep) concentrations. SOC and Fep in bulk soil and >5 mm aggregates were significantly related with MWD, and significant relationship was observed between MWD and Feo in <5 mm fractions. Thus, the high levels of SOC, alkane-C, Feo and Fep in soil after straw returning were responsible for the aggregate stability, but the effect of potassium application is not obvious in a rice–rape cropping system.

2021 ◽  
Vol 13 (3) ◽  
pp. 1541
Author(s):  
Xiaolin Shen ◽  
Lili Wang ◽  
Qichen Yang ◽  
Weiming Xiu ◽  
Gang Li ◽  
...  

Our study aimed to provide a scientific basis for an appropriate tillage management of wheat-maize rotation system, which is beneficial to the sustainable development of agriculture in the fluvo-aquic soil areas in China. Four tillage treatments were investigated after maize harvest, including rotary tillage with straw returning (RT), deep ploughing with straw returning (DP), subsoiling with straw returning (SS), and no tillage with straw mulching (NT). We evaluated soil organic carbon (SOC), dissolved organic carbon (DOC), permanganate oxidizable carbon (POXC), microbial biomass carbon (MBC), and particulate organic carbon (POC) in bulk soil and soil aggregates with five particle sizes (>5 mm, 5–2 mm, 2–1 mm, 1–0.25 mm, and <0.25 mm) under different tillage managements. Results showed that compared with RT treatment, NT treatment not only increased soil aggregate stability, but also enhanced SOC, DOC, and POC contents, especially those in large size macroaggregates. DP treatment also showed positive effects on soil aggregate stability and labile carbon fractions (DOC and POXC). Consequently, we suggest that no tillage or deep ploughing, rather than rotary tillage, could be better tillage management considering carbon storage. Meanwhile, we implied that mass fractal dimension (Dm) and POXC could be effective indicators of soil quality, as affected by tillage managements.


2018 ◽  
Author(s):  
Lipeng Sun ◽  
Guoliang Wang ◽  
Hang Jing ◽  
Guobin Liu

Background: Glomalin-related soil protein (GRSP) and soil organic carbon (SOC) contribute to the formation and stability of soil aggregates, but the mechanism by which global atmospheric nitrogen (N) deposition changes soil aggregate stability when it alters the distribution of GRSP and SOC in different aggregate fractions remains unknown. Methods: We used a gradient N addition (0–9 g N–2 y–1) in Pinus tabulaeformis forest for 2 years in northeast China and then examined the changes in SOC contents, total GRSP (T-GRSP), and easily extractable GRSP (EE-GRSP) contents in three soil aggregate fractions (macro-aggregate: >250 μm, micro-aggregate: 250–53 μm, and clay–silt aggregate: <53 μm) and their relationship with aggregate stability. Results: (1) The soil was dominated by macro-aggregates. Short term N addition had no significant effect on mean weight diameter (MWD) and geometric mean diameter (GMD). (2) GRSP varied among aggregate fractions, and N addition had variable effects on the distribution of GRSP in aggregate fractions. The EE-GRSP content in the macro-aggregates increased initially and then decreased with increasing N addition levels, having a peak value of 0.480 mg/g at 6 g N–2 y–1. The micro-aggregates had the lowest EE-GRSP content (0.148 mg/g) at 6 g N–2 y–1. Furthermore, the T-GRSP content significantly increased in the aggregate fractions with the N addition levels. (3) The macro-aggregate had the highest SOC content, followed by the micro-aggregate and the clay–silt aggregate had the lowest SOC content. N addition significantly increased the SOC content in all the aggregate fractions. (4) GRSP and SOC contents were not significantly correlated with MWD. Conclusion: The distributions of GRSP and SOC varied with aggregate fractions. GRSP and SOC contents increased by N addition, but this increase did not enhance aggregate stability in short term, and the improvement of stability might depend on binding agents and incubation time.


2021 ◽  
Vol 67 (No. 3) ◽  
pp. 173-181
Author(s):  
Yufei Liu ◽  
Xiaoxu Fan ◽  
Tong Zhang ◽  
Xin Sui ◽  
Fuqiang Song

Atrazine is still widely used in China. Atrazine residue (1.86–1 100 mg/kg) in the soil has exceeded the allowable limit (1.0 mg/kg), affecting soil structure and soil aggregate composition. To understand the long-term application of atrazine on soil aggregates and the binding agent, four treatments were established in cornfield planted since 1998, including without atrazine applied (AT<sub>0</sub>), atrazine applied (28% atrazine, 1 200–1 350 mL/ha/year) once a year from 2012 to 2018 (AT<sub>6</sub>, 167 mg/kg), from 2008 to 2018 (AT<sub>10</sub>, 127.64 mg/kg) as well as from 2002 to 2018 (AT<sub>16</sub>, 102 mg/kg) with three replications. Along with the increase of atrazine application time, the mass fraction of soil aggregates &gt; 5 mm and 2–5 mm decreased significantly while the mass fraction of soil aggregates 0.5–2 mm and &lt; 0.5 mm increased gradually, and the change of aggregate binding agents contents were the same as that of aggregates. The contents of soil organic carbon (SOC) and glomalin-related soil protein (GRSP) in the aggregates &gt; 5 mm and 2–5 mm were significantly negatively correlated with the years of atrazine application. Our results show that although atrazine residue in the soil does not increase with the increased yearly application, its concentration is still markedly higher than the permitted limit value and seriously affected the content of SOC and GRSP of aggregates &gt; 2 mm, which can lead to a decrease of soil aggregate stability and soil quality.  


2018 ◽  
Author(s):  
Lipeng Sun ◽  
Guoliang Wang ◽  
Hang Jing ◽  
Guobin Liu

Background: Glomalin-related soil protein (GRSP) and soil organic carbon (SOC) contribute to the formation and stability of soil aggregates, but the mechanism by which global atmospheric nitrogen (N) deposition changes soil aggregate stability when it alters the distribution of GRSP and SOC in different aggregate fractions remains unknown. Methods: We used a gradient N addition (0–9 g N–2 y–1) in Pinus tabulaeformis forest for 2 years in northeast China and then examined the changes in SOC contents, total GRSP (T-GRSP), and easily extractable GRSP (EE-GRSP) contents in three soil aggregate fractions (macro-aggregate: >250 μm, micro-aggregate: 250–53 μm, and clay–silt aggregate: <53 μm) and their relationship with aggregate stability. Results: (1) The soil was dominated by macro-aggregates. Short term N addition had no significant effect on mean weight diameter (MWD) and geometric mean diameter (GMD). (2) GRSP varied among aggregate fractions, and N addition had variable effects on the distribution of GRSP in aggregate fractions. The EE-GRSP content in the macro-aggregates increased initially and then decreased with increasing N addition levels, having a peak value of 0.480 mg/g at 6 g N–2 y–1. The micro-aggregates had the lowest EE-GRSP content (0.148 mg/g) at 6 g N–2 y–1. Furthermore, the T-GRSP content significantly increased in the aggregate fractions with the N addition levels. (3) The macro-aggregate had the highest SOC content, followed by the micro-aggregate and the clay–silt aggregate had the lowest SOC content. N addition significantly increased the SOC content in all the aggregate fractions. (4) GRSP and SOC contents were not significantly correlated with MWD. Conclusion: The distributions of GRSP and SOC varied with aggregate fractions. GRSP and SOC contents increased by N addition, but this increase did not enhance aggregate stability in short term, and the improvement of stability might depend on binding agents and incubation time.


2005 ◽  
Vol 2 (2) ◽  
pp. 159-174 ◽  
Author(s):  
D. Huygens ◽  
P. Boeckx ◽  
O. Van Cleemput ◽  
C. Oyarzún ◽  
R. Godoy

Abstract. Extreme sensitivity of soil organic carbon (SOC) to climate and land use change warrants further research in different terrestrial ecosystems. The aim of this study was to investigate the link between aggregate and SOC dynamics in a chronosequence of three different land uses of a south Chilean Andisol: a second growth Nothofagus obliqua forest (SGFOR), a grassland (GRASS) and a Pinus radiata plantation (PINUS). Total carbon content of the 0-10cm soil layer was higher for GRASS (6.7 kg C m-2) than for PINUS (4.3 kg C m-2, while TC content of SGFOR (5.8 kg C m-2) was not significantly different from either one. High extractable oxalate and pyrophosphate Al concentrations (varying from 20.3-24.4 g kg-1, and 3.9-11.1 g kg-1, respectively) were found in all sites. In this study, SOC and aggregate dynamics were studied using size and density fractionation experiments of the SOC, δ13C and total carbon analysis of the different SOC fractions, and C mineralization experiments. The results showed that electrostatic sorption between and among amorphous Al components and clay minerals is mainly responsible for the formation of metal-humus-clay complexes and the stabilization of soil aggregates. The process of ligand exchange between SOC and Al would be of minor importance resulting in the absence of aggregate hierarchy in this soil type. Whole soil C mineralization rate constants were highest for SGFOR and PINUS, followed by GRASS (respectively 0.495, 0.266 and 0.196 g CO2-Cm-2d-1 for the top soil layer). In contrast, incubation experiments of isolated macro organic matter fractions gave opposite results, showing that the recalcitrance of the SOC decreased in another order: PINUS>SGFOR>GRASS. We deduced that electrostatic sorption processes and physical protection of SOC in soil aggregates were the main processes determining SOC stabilization. As a result, high aggregate carbon concentrations, varying from 148 till 48 g kg-1, were encountered for all land use sites. Al availability and electrostatic charges are dependent on pH, resulting in an important influence of soil pH on aggregate stability. Recalcitrance of the SOC did not appear to largely affect SOC stabilization. Statistical correlations between extractable amorphous Al contents, aggregate stability and C mineralization rate constants were encountered, supporting this hypothesis. Land use changes affected SOC dynamics and aggregate stability by modifying soil pH (and thus electrostatic charges and available Al content), root SOC input and management practices (such as ploughing and accompanying drying of the soil).


2005 ◽  
Vol 2 (1) ◽  
pp. 203-238 ◽  
Author(s):  
D. Huygens ◽  
P. Boeckx ◽  
O. Van Cleemput ◽  
R Godoy ◽  
C. Oyarzún

Abstract. The extreme vulnerability of soil organic carbon to climate and land use change emphasizes the need for further research in different terrestrial ecosystems. We have studied the aggregate stability and carbon dynamics in a chronosequence of three different land uses in a south Chilean Andisols: a second growth Nothofagus obliqua forest (SGFOR), a grassland (GRASS) and a Pinus radiata plantation (PINUS). The aim of this study was to investigate the role of Al as soil organic matter stabilizing agent in this Andisol. In a case study, we linked differences in carbon dynamics between the three land use treatments to physical protection and recalcitrance of the soil organic matter (SOM). In this study, C aggregate stability and dynamics were studied using size and density fractionation experiments of the SOM, δ13C and total carbon analysis of the different SOM fractions, and mineralization measurements. The results showed that electrostatic attractions between and among Al-oxides and clay minerals are mainly responsible for the stabilization of soil aggregates and the physical protection of the enclosed soil organic carbon. Whole soil C mineralization rate constants were highest for SGFOR and PINUS, followed by GRASS. In contrast, incubation experiments of isolated macro organic matter fractions showed that the recalcitrance of the SOM decreased in another order: PINUS > SGFOR > GRASS. We concluded that physical protection of soil aggregates was the main process determining whole soil C mineralization. Land use changes affected soil organic carbon dynamics in this south Chilean Andisol by altering soil pH and consequently available Al.


Author(s):  
Wei Zhou ◽  
Xiangyang Sun ◽  
Suyan Li ◽  
Tiantian Du ◽  
Yi Zheng ◽  
...  

AbstractUrban forest soil is often disturbed by rapid urbanization. Organic mulching is effective for improving soil quality and aggregate stability. This study evaluated how soil binding agents changed aggregate stability through organic mulching in urban forest soils. Three treatments were applied in Jiufeng National Forest Park, Beijing: (1) no organic mulch (control); (2) wood chips alone (5 cm thickness); and, (3) wood chips + wood compost (This mulch was divided into two layers, the upper layer of wood chips (2.5 cm), the lower layer wood compost (2.5 cm)). Soil samples were collected from the surface 10- cm soil layer and fraction into four aggregates. Glomalin-related soil protein and soil organic carbon were measured in bulk soil and the four aggregates. The results show that wood chips + wood compost increased the proportion of large and small macroaggregates, mean weight diameter and geometric mean diameter. The total and easily extractable glomalin-related soil protein were higher in the wood chips + wood compost. However, soil organic carbon was lower in the wood chips alone application compared to the controls and wood chips + wood compost. Easily extractable / total glomalin-related soil protein and glomalin-related soil protein / soil organic carbon ratios of wood chips alone and wood chips + wood compost had increased trend compared to the controls but did not reach significant levels (p > 0.05). Mean weight diameter and geometric mean diameter correlated positively with total and easily extractable glomalin-related soil protein but were not positively correlated with soil organic carbon, the ratios of easily extractable and total glomalin-related soil protein, and the ratios of glomalin-related soil protein and soil organic carbon. Redundancy analysis revealed that total glomalin-related soil protein was the most important driver for soil aggregate stability, especially the total glomalin-related soil protein of small macroaggregates. The results suggest that wood chips + wood compost enhanced soil aggregate stability through the increase of glomalin-related soil protein. Wood chips alone cannot enhance soil aggregate stability in urban forests in the short term.


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