[Impact of Climate Warming on Paddy Soil Organic Carbon Change in the Sichuan Basin of China].

Climate warming can increase soil temperature and lead to soil carbon release, but it can also increase soil organic carbon by increasing primary productivity. Cropland soils are considered to have a huge potential to sequester carbon; however, direct observations for the responses of cropland soil organic carbon to climate warming over broad geographic scales are rarely documented. Paddy soil is one of the important cultivated soils in China. Based on the data of 2217 sampling points obtained during the second national soil survey and the data of 2382 sampling points collected during 2017-2019, this study analyzed the change characteristics of soil organic carbon content of paddy surface soil in Sichuan Basin of China and explored the relationships between the soil organic carbon change of paddy soil and temperature, precipitation, cropland use type, fertilization intensity, and grain yield. The results showed that the content of soil organic carbon of paddy soil changed from 13.33 g·kg-1to 15.96 g·kg-1, with an increase of 2.63 g·kg-1, suggesting that soils in the Sichuan Basin have acted as a carbon sink over past 40 years. The soil organic carbon increment of paddy soil varied with different geomorphic regions and different secondary basins. The increase in SOC content in paddy soil was positively correlated with annual average temperature; negatively correlated with annual average precipitation; and initially increased and then decreased with annual average fertilizer application, annual average increase rate of fertilizer application, annual average grain yield, and annual average grain yield growth rate. The relationship between the increase in SOC content and the annual average temperature growth rate was different under different farmland utilizations, and the increase in the annual average temperature growth rate had significant effects with the increase in SOC content only on paddy-dryland rotation. These results indicate that the paddy soil organic carbon change in Sichuan Basin was co-affected by various factors, but climate warming was an important factor leading to the paddy soil organic carbon change, and its influence was controlled by the water conditions determined by farmland use.

[Analysis of Spatial Distribution and Influencing Factors of Nitrogen and Phosphorus Fertilizer Application Intensity in Chengdu Plain].

The spatial distribution of fertilization intensity and its influencing factors are significant for the accurate management of fertilization and pollution prevention and control. Previous studies are mostly limited to the discussion of human factors that influences the spatial distribution of fertilization intensity while ignoring natural geographical factors. Based on the chemical fertilizer survey data collected from 23492 sites in Chengdu Plain and combined with Geostatistics analysis and Geographic Information System (GIS) technology, the spatial distribution characteristics and influencing factors of average nitrogen and phosphorus fertilizer application intensity from 2010 to 2015 in this region were explored. The results show that:① the average annual application intensity of nitrogen and phosphorus fertilizer in the study area from 2010 to 2015 is generally in the low and medium risk intensity of 120-360 kg·hm-2 and 60-180 kg·hm-2. The high risk intensity is mainly distributed in the grain (fruit) and vegetable growing areas such as Pidu, Pengzhou, Shifang, Longquanyi and Jintang, while the relatively low value areas are mostly distributed in the south and northeast. ② the nugget coefficients of nitrogen and phosphorus fertilizer application intensities are 66.17% and 41.60%. Their spatial distribution is determined by structural and random factors, showing a moderate spatial autocorrelation. ③ both human and natural factors have significant effects on the application intensity of nitrogen and phosphorus fertilizer. The crop type (fine classification) can explain the spatial variation of nitrogen fertilizer and phosphorus fertilizer respectively by 12.90% and 25.10%, which is the main controlling factor affecting the spatial distribution of nitrogen and phosphorus application intensity; the importance of soil parent material is second only to the planting crop type, and the independent explanation ability of phosphorus application intensity is about 3.6 times higher than that of nitrogen application intensity. When the type of planting crop plays a decisive role, the soil parent material still deeply restricts and affects the spatial distribution of nitrogen and phosphorus fertilizer application intensity in the study area. Therefore, the comprehensive effects of planting crop types and soil parent materials should be considered in fertilization management and environmental risk analysis, and the effects of soil parent material should also be taken into account in the application of phosphate fertilizer.

[Effects of different land use patterns on soil potassium distribution in Chengdu Plain, China]. / æˆéƒ½å¹³åŽŸä¸åŒåœŸåœ°åˆ©ç”¨æ–¹å¼å¯¹åœŸå£¤å‰–é¢é’¾ç´ åˆ†å¸ƒçš„å½±å“.

To explore the effects of land use change on the potassium in soil profile under the background of rapid urbanization, we collected data of 187 soil profiles from four typical land use patterns (rice-wheat, rice-vegetable, rice-oil and garden) in Chengdu Plain. The contents of available potassium (AP), slow-acting potassium (SP), mineral potassium (MP), and total potassium (TP) in soil profile under different land use patterns and their relationships were analyzed. Our results showed that compared with the traditional rotation (rice-wheat, rice-oil), soil AP and SP contents significantly varied among different land use patterns. Rice-vegetable rotation increased the contents of AP and SP in the surface soil, while garden land increased the consumption of AP and SP in the soil. For the more stable forms, soil MP and TP, there was no significant difference in their contents under different land use patterns. In the deep soil, the content of AP in the rice-vegetable rotation pattern was significantly decreased with deepening soil layer, and the AP in traditional rotation was significantly higher than that in garden land. The trend of SP was opposite to that of AP. The difference of MP and TP in different land use patterns was small. Among the four land use patterns, the ratio of AP to TP and SP to TP in the lower layer of rice-vegetable rotation was higher than that in other patterns, while the ratio of AP to TP decreased significantly under different land use patterns at 20-40 cm. The change of SP to TP with the downward ratio of soil layer was opposite to that of AP to TP. Additionally, the ratio of MP to TP was relatively stable under different land use patterns. Therefore, different land use patterns exerted significant effects on the distribution of AP and SP in the soil profile of Chengdu Plain.

[Profile Distribution of Paddy Soil Organic Carbon and Its Influencing Factors in Chengdu Plain].

Understanding the effects of environmental factors on the profile distribution of soil organic carbon (SOC) is a base to accurately modeling the continuous change of SOC in vertical and three-dimensional spatial distributions, as well as precisely estimating SOC storage. Based on 171 soil profiles collected from Chengdu Plain, the effects of environmental factors (including the parent material, soil type, elevation, distance from river, and land use) on the profile distribution of paddy SOC to a depth of 1 m were evaluated through the exponential decay function. The results indicated that SOC was estimated at 19.42, 9.59, 5.99, and 5.20 g·kg-1 at depths of 0-20, 20-40, 40-60, and 60-100cm, respectively, showing a significant decrease with increased depth. Soil organic carbon was mainly concentrated above a 40 cm soil depth, accounting for 72.17% of the total profile, which could be crucial to studying the carbon source/sink of paddy soils in Chengdu Plain. The parameters of the exponential decay function had a similar spatial pattern, indicating their spatial dependence. The nugget coefficients for C and k were 55.400% and 47.671%, respectively, indicating that paddy SOC in the study area was affected by both structural and random factors. Regression analysis implied that the parent material and soil genius were the dominant factors influencing the profile distribution of SOC. Nevertheless, elevation, distance from river, and land use should also be taken into consideration. It has been concluded that the parent material and soil genius should be premeditated when fitting the vertical distribution of SOC, modeling the three-dimensional prediction of soil organic carbon, and estimating soil carbon storage in the paddy soils of Chengdu Plain.

[Spatial variability of soil nitrogen and related affecting factors at a county scale in hilly area of Mid-Sichuan Basin].

Spatial distribution characteristics of soil total nitrogen ( TN ) and available nitrogen ( AN ) were analyzed by using geostatistical methods and the effects of the influencing factors were quantified by regression analysis based on 555 soil samples collected in RenShou county. The results showed that the contents of soil TN ranged from 0.34-2.57 g x kg(-1) with a mean value of 1.12 g x kg(-1), which indicated the TN of the study area was at a medium level, and AN ranged from 25.86-184.17 mg x kg(-1) with a mean value of 74.35 mg x kg(-1), which indicated the AN of the study area was low. The values of the nugget to sill ratio were 0.608 and 0.790 respectively, which suggestd TN had moderate spatial dependence, which was determined by the co-effects of structural and random factors, while AN was mainly affected by random factors. The contents of TN and AN in north area were much higher than those of south area and distribution of Patchy. The soil parent materials were able to explain 6.3% and 1.0% of TN and AN spatial variability. Soil types explained 26.5% - 36.1% of TN variability and 27.7% - 28.7% of AN variability. Topographical factors explained 5.5% of TN variability and 6.1% of AN variability, the structural factors of soil types reflected spatial variability of nitrogen in the study area. The randomness factors of land use types explained 37.7% of TN variability and 40.0% of AN variability that were much larger than the other factors, which suggested land use had the higherst independent explaining capacity for nitrogen spatial variability among those influence factors and land use type was the main factor to accurately predict the spatial distribution of soil nitrogen in the hilly area of Middle Sichuan Basin.

[Spatial variability of soil C/N ratio and its influence factors at a county scale in hilly area of Mid-Sichuan Basin, Southwest China].

Spatial distribution characteristics of soil C/N ratio and its affecting factors at a county scale in hilly area of Middle Sichuan Basin were analyzed based on field sampling. Result indicated that soil C/N ranged from 4.84 to 21.79, with a mean value of 11.93. The coefficient of variation was 26.3%; which suggested soil C/N had moderate variability in this study area. The ratio of nugget to sill was 73.0%, which suggested the spatial variability of soil C/N was determined by both structural and random factors, and the random factors played a more important role. The soil C/N was higher in northeast and southwest while the central part of the study area was characterized by relatively lower values of soil C/N. The soil C/N ranged from 10.0 to 13.5 in most parts of the study area. Parent material, soil type, topographic factors and land use type had significant impacts on soil C/N (P<0.05). Soil C/N showed a significant positive correlation with elevation and slope (P<0.05). The soil parent materials were able to explain 8.7% of soil C/N spatial variability. The explanatory power of soil group, subgroup and soil genus were 3.8%, 5.0%, 8.7%, respectively. Topographic factors showed the lowest explanatory power of only 0. 8%. However, land use type could explain 23.9% of the spatial variability, which suggested that land use type was the dominant factor in controlling the spatial variability of soil C/N.

[Clinical effect of modified Xuefuzhuyutang on senile chronic subdural hematoma after operation].

OBJECTIVE: To investigate the curative effect of modified Xuefuzhuyutang on chronic subdural hematoma (CSDH)after burr holes irrigation and drainage. METHODS: From January 2010 to April 2013,137 CSDH patients were randomly divided into two groups: 65 cases of control group and 72 cases of medicine group (modified Xuefuzhuyutang). RESULTS: Compared with the control group, the cases of total absorption of hematoma in medicine group increased significantly (P < 0.05). The cases of 50%-99%, 30%-49% and 0%-29% absorption in above two groups had no significant differences (P > 0.05). There were no significant side effects were observed in the two groups. Compared with the control group, the marked effective cases and total effective cases in medicine group were higher (P < 0.05). CONCLUSION: Modified Xuefuzhuyutang is effective in reducing the postoperative residual volume and recurrent CS-DH.

[Prediction of soil nutrients spatial distribution based on neural network model combined with goestatistics].

In this study, a radial basis function neural network model combined with ordinary kriging (RBFNN_OK) was adopted to predict the spatial distribution of soil nutrients (organic matter and total N) in a typical hilly region of Sichuan Basin, Southwest China, and the performance of this method was compared with that of ordinary kriging (OK) and regression kriging (RK). All the three methods produced the similar soil nutrient maps. However, as compared with those obtained by multiple linear regression model, the correlation coefficients between the measured values and the predicted values of soil organic matter and total N obtained by neural network model increased by 12. 3% and 16. 5% , respectively, suggesting that neural network model could more accurately capture the complicated relationships between soil nutrients and quantitative environmental factors. The error analyses of the prediction values of 469 validation points indicated that the mean absolute error (MAE) , mean relative error (MRE), and root mean squared error (RMSE) of RBFNN_OK were 6.9%, 7.4%, and 5. 1% (for soil organic matter), and 4.9%, 6.1% , and 4.6% (for soil total N) smaller than those of OK (P<0.01), and 2.4%, 2.6% , and 1.8% (for soil organic matter), and 2.1%, 2.8%, and 2.2% (for soil total N) smaller than those of RK, respectively (P<0.05).

Relationship between species diversity and ecotope diversity.

The relationship between species diversity and ecotope diversity has long been debated. But these debates seem meaningless because most of them were based on different definitions. In this paper, diversity has two components: richness based on the total number and evenness based on the relative abundance. Species diversity is distinguished into individual-counting diversity and biomass-based diversity. Ecotope diversity is divided into individual ecotope-counting diversity and ecotope-area based diversity. Under this definition, we make a comprehensive investigation into Dongzhi tableland of Loess Plateau by cooperating with local technicians. We find that individual-counting diversity is significantly correlated with biomass-based diversity in grassland ecosystems; individual ecotope-counting diversity and ecotope-area based diversity have a significant correlation. Therefore, it is unnecessary to divide species diversity into individual-counting diversity and biomass-based diversity in grassland ecosystems and to distinguish ecotope diversity into individual ecotope-counting and ecotope-area based diversity for the issues that have no special requirement for accuracy. But the analyses of the investigation data demonstrate that species diversity has no significant correlation with ecotope diversity.