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1.
Huan Jing Ke Xue ; 40(8): 3816-3824, 2019 Aug 08.
Artigo em Chinês | MEDLINE | ID: mdl-31854792

RESUMO

The distribution and stability of soil aggregates under different land use types, and the distribution of organic carbon in various aggregates, were explored in order to provide a basis for the improvement of soil structure and the maintenance and improvement of soil organic carbon in Chongqing. Focusing on six representative subtropical land use types in the Beibei District of Chongqing (coniferous and broadleaf mixed forest, bamboo forest, orchard, dryland, paddy field, and waste grassland), soils were sorted using the wet sieving method and the six soil types were compared and analyzed. The distribution of aggregates and their organic carbon content were determined at soil profile depths of 0-20, 20-40, 40-60, and 60-100 cm for each land use type. The results showed that there were significant differences in soil structure and fertility levels under the different land use types. Among the particle size aggregates of the 0-100 cm soil layer, the aggregate particle size of the six land use types was mainly >0.25 mm; the content of >0.25 mm aggregate fraction of bamboo forest soil is the highest, followed by the grassland soil, and the dryland and orchard soils is the lowest. Granular aggregates in the size class 0.25-2 mm were mainly distributed in the 0-20 cm soil layers (28.78%-50.08%), while the aggregate size fractions 0.053-0.25 mm and<0.053 mm were mainly concentrated in the 40-60 cm soil layers. Across the entire profile depth, the aggregate MWD and GMD of the bamboo forest and barren grassland soils were higher than the other land use types, i. e., the soil aggregates in these soils were more stable. The stability of soil aggregates was significantly positively correlated with soil aggregate organic carbon content (r=0.569, P<0.01). In the 0-100 cm soil layer, the organic carbon content of soil aggregates was higher for the 0.25-2 mm and<0.053 mm fractions, with an average content of 56.54 g·kg-1 in the 0.25-2 mm fraction. Except for the organic carbon content of the soil aggregates with different particle size of dryland was the highest in the 20-40 cm soil layer, while under the other land use types, the organic carbon content in soil aggregates decreased with depth, showing significant surface enrichment. Overall, under the six different land use types, the soil aggregates in bamboo forest soils and waste grassland soils showed good stability, and at each soil depth, the organic carbon content of aggregates was highest in the bamboo forest soil.

2.
Huan Jing Ke Xue ; 40(10): 4700-4707, 2019 Oct 08.
Artigo em Chinês | MEDLINE | ID: mdl-31854841

RESUMO

The ecosystem respiration and temperature sensitivity (Q10) of paddy soil play very important roles in the emission of greenhouse gases from paddy ecosystems. Under intermittent irrigation and flooding irrigation conditions, a static opaque chamber and gas chromatography method were applied to study the regulation and influence of ecosystem respiration and Q10 using five treatments:no fertilizer (CK), conventional fertilization (NPK), 10t·hm-2 biochar with chemical fertilizer (LBC), 20t·hm-2 biochar with chemical fertilizer (MBC), and 40t·hm-2 biochar with chemical fertilizer (HBC). The results showed that:① The temperature sensitivity coefficients (Q10) of ecosystem respiration under flooding irrigation were 4.45 (CK), 7.40 (NPK), 6.44 (LBC), 4.58 (MBC), and 3.87 (HBC), respectively. Flooding irrigation significantly reduced the Q10 value of the paddy field ecosystem compared to intermittent irrigation (P<0.01). CK, NPK, LBC, MBC, and HBC decreased by 48.6%, 55.2%, 67.9%, 70.3%, and 70.8% under flooding irrigation, respectively. ② Whether intermittent irrigation or flooding irrigation was adopted, the application of fertilizer with biochar increased the respiration of the paddy field ecosystem than conventional fertilization treatment, but the effect of different biochar levels on respiration was not significant. ③ The application of chemical fertilizer with medium or low amounts of biochar increased the temperature sensitivity of respiration compared with no fertilization in the paddy field ecosystems (P<0.05), but both MBC and HBC treatments reduced the Q10 value of paddy field ecosystem compared with NPK. Furthermore, the temperature sensitivity of respiration in the paddy field ecosystem decreased with an increase in the level of biochar application. Therefore, under the two irrigation methods, HBC treatment was more effective than LBC and MBC treatments to inhibit the effect of increasing soil temperature on the respiration of the ecosystem.

3.
Huan Jing Ke Xue ; 40(9): 4270-4277, 2019 Sep 08.
Artigo em Chinês | MEDLINE | ID: mdl-31854894

RESUMO

Phytolith-occluded organic carbon (PhytOC) is a form of long-term storage of soil organic carbon, which is of great significance for soil carbon sequestration. Taking six land use patterns in southwest China as the research object, including coniferous and broad-leaved mixed forest, bamboo forest, orchard, dry land, paddy field, and grassland, we compare the distribution of the PhytOC content under the different land use patterns in different depth sections of 0-20, 20-40, 40-60, and 60-100 cm. In addition, we estimate the storage of phytOC and analyze the carbon sequestration characteristics of the terrestrial ecosystems. According to the results, the soil organic carbon and phytolith mean content in the bamboo forest were the highest in the soil profile, at 16.75 g·kg-1 and 59.66 g·kg-1, respectively. In all soil layers, the phytolith content of the bamboo forest soil was significantly higher than that in other land use patterns (P<0.05). The average content of soil phytOC in the six land use patterns ranged from 0.55 to 1.96 g·kg-1, and the phytOC content of each layer of bamboo forest was higher than that in other land uses. The total carbon storage of phytOC in the bamboo forest soil, at 23.45 t·hm-2, was significantly higher than that of other soil use methods (P<0.05). Statistical analysis showed that soil silicon had a significant positive correlation with the soil phytolith and the soil phytOC (P<0.01). The soil phytolith and phytolith carbon content in different land use patterns generally showed a decrease with an increase in soil depth, and a certain surface enrichment phenomenon was noted.

4.
Huan Jing Ke Xue ; 40(3): 1504-1511, 2019 Mar 08.
Artigo em Chinês | MEDLINE | ID: mdl-31088003

RESUMO

This study was intended to explore the distribution and stability of soil aggregates and the organic carbon for different forest types and to provide a scientific basis for the efficient management of soil carbon pools in subtropical forest ecosystems. Four subtropical forest types, including bamboo forest, broad-leaf forest, coniferous forest, and a mixed coniferous and broad-leaf forest on Jinyun Mountain (Chongqing Municipality), were selected as research subjects to explore the distribution of soil aggregates and organic carbon in different layers (depths of 0-20, 20-40, 40-60, and 60-100 cm). The results showed:The content of >2 mm aggregates and mean weight diameter (MWD), geometric mean diameter (GMD), and >0.25 mm aggregate content (R0.25) in broad-leaf forests decreased with soil depth, while other forests did not have a similar distribution pattern. In each soil layer, bamboo forest soils were mainly composed of >2 mm fractions of aggregates, which made up 30.73%-53.08% of the total content; The content of 2-0.25 mm particle size aggregates of broad-leaf and mixed forest soils was higher than that for other sizes, and its content ranged from 36.27% to 44.67% and 48.69% to 52.44%, respectively. The 2-0.25 mm and <0.053 mm fractions of aggregates dominated conifer soils. In general, the MWD, GMD, and R0.25 of bamboo aggregates were higher than for other stands in each soil layer, and the fractal dimension (D) was lower than for other stands. This indicated that the soil aggregates of bamboo forest have better stability. As the soil layer deepened, the organic carbon content of soil aggregates in forest types, except for coniferous forest, gradually decreased. Among them all, bamboo forest aggregates had the highest organic carbon content, and this was significantly higher than that of coniferous forest and mixed forest. In the whole soil profile, as far as different aggregate size is concerned, there was no obvious regularity about organic carbon in the four forest types soil aggregates; the organic carbon content of the 2-0.25 mm and <0.053 mm fractions of aggregates was high in every soil layer. There was a significant difference in the relative contribution of organic carbon in soil aggregates for different forest stands, among these contributions, the contribution rate of organic carbon in the <0.053 mm fraction of aggregates in the coniferous forest was the highest. The organic carbon contribution rate of the >2 mm fraction of bamboo forest aggregates was as high as 27.44%-53.47%. Broad-leaf forests and mixed forests had the highest contribution to the organic carbon of the 2-0.25 mm fractions of soil aggregates. Among the four forest types on Jinyun Mountain, the soil aggregates in bamboo forest have better stability, but the stability of aggregates in coniferous forests is poor. In each soil layer, the content of bamboo forest organic carbon in the various aggregates was the highest, and that of coniferous forest was the lowest.


Assuntos
Carbono/análise , Florestas , Solo/química , China
5.
Huan Jing Ke Xue ; 39(9): 4338-4347, 2018 Sep 08.
Artigo em Chinês | MEDLINE | ID: mdl-30188079

RESUMO

The effects of different straw and biochar applications on the carbon balance of a farmland ecosystem were studied under a rape-maize rotation planting system. The study explored impact of straw and biochar addition on soil carbon sequestration. A field experiment was carried out at the National Monitor Station of Soil Fertility and Fertilizer Efficiency of Purple Soils (Chongqing, China). Five treatments, i.e., control (CK, no organic material), straw only (CS), straw and microorganism (CSD), half straw and half biochar (CSBC), and biochar only (BC), were applied. In-situ cumulative emissions of soil total carbon were subsequently monitored. Based on field experiment and survey data, carbon emissions, carbon sequestration, and and economic and environmental benefits were analyzed for soil respiration, soil carbon pool, crop carbon pool, as well as the cost of agricultural inputs after straw and biochar application. The main results were:①Accumulative emissions of soil carbon during two planting seasons were all higher with treatment than in CK, and the differences between CS, CSD, and CK were significant (P<0.05). ②Compared with CK, both straw and biochar treatments increased crop yield (by 1.49%-3.92%) and crop net primary productivity (NPP) increased by 4.44%-17.90%. Largest yields and NPP during both seasons were achieved with CSD.③Net carbon sequestration was positive during both seasons in all treatments without CK, indicating a carbon sink effect. The highest net carbon sequestration was obtained with CSD (9.05 t·hm-2) and BC (10.75 t·hm-2) treatments. The lowest carbon emissions were obtained with the BC treatment, with emissions 62.69%-81.86% lower than CK. ④The highest production to cost ratio was obtained with CS treatments during the rape planting season. Application of only biochar reduced the production to cost ratio but increased the carbon trading income (466.95-561.22 yuan·hm-2).⑤BC treatment increased carbon productivity (CP) in both seasons, while the economic (CJ) and ecological benefits(CE) of BC treatment were significantly lower than with other treatments. The addition of straw increases economic and ecological benefits; however, addition of biochar reduces such benefits.


Assuntos
Agricultura/métodos , Brassica rapa/crescimento & desenvolvimento , Carbono/análise , Carvão Vegetal , Solo/química , Zea mays/crescimento & desenvolvimento , China , Fertilizantes , Caules de Planta
6.
Huan Jing Ke Xue ; 39(1): 355-362, 2018 Jan 08.
Artigo em Chinês | MEDLINE | ID: mdl-29965702

RESUMO

The aim of this work is to understand the effects of straw and biochar return in soil on the content, distribution, stability, and relative contribution rate of organic carbon for soil aggregates, which could be used to better understanding the stability of the soil carbon pool and the protection mechanisms under straw and biochar return. In this study, a field experiment was conducted to study the effects of straw and biochar return on soil aggregates and carbon sequestration characteristics in a rape-maize rotation planting system. Five treatments, including a control (no organic material added, CK), straw (CS), straw and microorganism (CSD), Biochar (BC), half straw and half biochar (CSBC), were used. The results indicated that ① Straw and biochar could improve the content of soil organic carbon, and the BC and CSBC treatments increased it by 16.88-17.37 g·kg-1, values higher than those with the CS and CSD treatments (13.76-14.68 g·kg-1); ② Compared with the CK treatment, CS and CSD treatments could increase the stability of the aggregates through significantly increasing the content of macro-aggregate by 94.00%-117.78% and significantly increasing the mean weight diameter (MWD), geometric mean diameter (GMD), and R0.25 of water stable aggregates, but reducing the D value (P<0.05); and ③ With the increase in aggregate particle size, the content of organic carbon in the aggregates decreased first and then increased. The contribution rate of soil organic carbon in silt and clay was the highest (29.61%-42.18%), and the contribution rate of organic carbon in the macro-aggregate was the lowest (9.19%-17.81%). In addition to the CSD treatment, the CS, BC, and CSBC treatments reduced the contribution of larger aggregates (2-0.25 mm) and micro-aggregates (0.25-0.053 mm). In general, the benefit of straw return was better than that of biochar in promoting soil aggregation. However, the application of biochar was better than straw in improving the aggregates organic carbon content. The newly generated carbon from straw degradation was mainly distributed in large aggregates. Straw with microorganisms could promote the combination of carbon by different components in the larger aggregates. The carbon from biochar and straw with biochar treatments were mainly concentrated in micro-aggregates.


Assuntos
Sequestro de Carbono , Carvão Vegetal , Solo/química , Carbono , Caules de Planta
7.
Huan Jing Ke Xue ; 37(7): 2770-2778, 2016 Jul 08.
Artigo em Chinês | MEDLINE | ID: mdl-29964490

RESUMO

In order to better understand the effect of reduced phosphorus fertilizer and combining organic fertilizers on phosphorus loss of purple soil sloping field, three rainfall-runoff events were monitored using field runoff observation method in the purple soil sloping field in 2014. There were six treatments in this research, including optimized fertilization (P), optimized fertilization+pig manure application (MP), optimized fertilization+straw return (SP), optimized fertilization which was reduced by 20%+pig manure application (MDP), optimized fertilization which was reduced by 20%+straw return (SDP), without phosphate (P0). The results indicated that the interflow was the main pathway of runoff for purple soil sloping field. The average contents of total phosphorus (TP) and the phosphorus loss load of overland flow were all much higher than those of the interflow. The overland flow was the main pathway of the phosphorus loss load for purple soil sloping field. Reduced phosphorus fertilizer and combining organic fertilizers had a significant reduction effect on phosphorus loss of purple soil sloping field. Compared with the treatment P, the average content of total phosphorus on SDP was reduced by 57% and that on MDP was reduced by 48% in the storm rainfall. Combining straw was better than pig manure. The average contents of the phosphorus loss load of typical rainfall changed between 0.01 and 0.26 kg·hm-2. In different fertilization treatments, the average contents of the phosphorus loss load followed the order of P > MP > SP > MDP > SDP > P0. Reduced phosphorus fertilizer and combining organic fertilizers had a significant reduction effect on phosphorus loss of overland flow, but increased soil phosphorus leaching for purple soil sloping field.


Assuntos
Fertilizantes , Esterco , Fósforo/química , Solo/química , Agricultura , Animais , Fosfatos , Suínos
8.
Huan Jing Ke Xue ; 37(6): 2284-2290, 2016 Jun 08.
Artigo em Chinês | MEDLINE | ID: mdl-29964898

RESUMO

In this study the effects of tillage methods (rice-winter paddy field conventional farming, CF; rice-winter paddy field combing ridge with no-tillage, RNT1; rice-wheat or rape combing ridge with no-tillage, RNT2; rice-wheat or rape conventional paddy-upland rotation tillage, CR) on purple soil profile of different forms of inorganic phosphorus distribution characteristics were investigated in a long-term experimental site established in 1990, Chongqing City, China. The results showed that compared to the status before the experiment, the total phosphorus, available phosphorus and various morphologies of inorganic phosphorus all increased to a certain degree in the soils with different long-term tillage treatments,and the contents of different forms of inorganic phosphorus in soil size ranked as RNT2> CF> CR> RNT1. Except that the contents of Fe-P in the lower layer were higher than those in the upper layer, contents of Ca2-P, Ca8-P, Al-P, Ca10-P and O-P in the arable layers were all higher than those in the lower layers. The effects of farming practices on the availability of various phosphorus forms were significant. They were in the order of CR> RNT> CF. Long-term conventional paddy-upland rotation tillage was more advantageous to crops in the absorption of phosphorus. It was shown by relevant analysis that the contribution of various groups of inorganic phosphorus to purple soil was in the order of Ca2-P(0.9369)> Al-P(0.9158)> Ca8-P(0.9012)> Fe-P(0.8287)> Ca10-P(0.8059)> O-P(0.7472).


Assuntos
Agricultura/métodos , Fósforo/química , Solo/química , Brassica rapa/crescimento & desenvolvimento , China , Produtos Agrícolas/crescimento & desenvolvimento , Oryza/crescimento & desenvolvimento
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