[Response of Soil Organic Carbon Accumulation in Paddy Fields in Fujian Province to Future Temperature Increases].

Understanding the effect of the soil carbon "source-sink" in cropland in China under future warming scenarios is the basis for making reasonable carbon neutralization policies. This study focused on the paddy soil in Fujian Province, a typical subtropical region in China including 84 counties (cities and districts). We employed the 1:50000 soil database and biogeochemical process model (DNDC) to simulate the dynamic changes in paddy soil organic carbon under different warming scenarios for the period of 2017-2053. The results indicated that in the context of normal temperature (control run) and 2, 4, and 6℃ of warming, the total amounts of carbon sequestration of paddy soil in Fujian Province were 11.56,9.44, 7.08, and 4.91 Tg, respectively; accordingly, the average annual carbon sequestration rates (expressed by C) were 173, 141, 106, and 74 kg·(hm2·a)-1, indicating that the rate of carbon sequestration was decreasing with the increase in future temperature. However, overall, the paddy field soil in the province was still a "carbon sink" under the warming of 6 (C. We also found that the gleyed paddy soil was mostly affected by the increase in temperature, and the decrease in carbon sequestration rate ranged from 20% to 69% using different treatments. In contrast, the salinized paddy soil was slightly affected, with a 14%-43% decrease in carbon sequestration rates. As for the different administrative regions, Sanming City was the most affected by temperature increase, with the rate of carbon sequestration decreasing by 27%-83% using different treatments. However, it was reduced by only 10%-41% and 14%-42% in Quanzhou and Putian (coastal areas), respectively. Overall, due to different soil properties, fertilization management, and climatic environment, there was a strong variability in the carbon sequestration rates of paddy soil for different soil subtypes and administrative regions in Fujian in response to future climatic warming.

[Enrichment and Ecological Risk Assessment of Available Phosphorus in Paddy Soil of Fujian Province Over Past 40 years].

The ecological risks such as water eutrophication caused by soil phosphorus loss have attracted extensive attention, and its dynamic changes and enrichment effects are the basis for formulating reasonable control measures. In this study, based on the paddy soils of 1.8×106 hm2 in Fujian province, the dynamic changes and ecological risks of available phosphorus in paddy soils over the past 40 years were analyzedusing a soil database of 1:50000. The soil database contained 1471, 215534, and 2895 paddy soil samples in different periods, respectively. The paddy soil samples were derived from the 1982 Second National Soil Census, the 2008 Ministry of Agriculture and Rural Areas Soil Testing and Formulated Fertilization Project and the 2018 Ministry of Agriculture, and the Rural Areas Arable Land Quality Monitoring Project, respectively. The results showed that from 1982 to 2018, the content of available phosphorus in paddy soils increased by 47 mg·kg-1, and the enriched area reached 1.65×106 hm2, accounting for 91% of the total paddy soils in Fujian province. From 1982 to 2008, the available phosphorus content of paddy soils in Fujian province increased by 28 mg·kg-1, with the enriched area reaching 1.47×106 hm2, accounting for 82% of the total paddy soils in Fujian province. From 2008 to 2018, the available phosphorus content of paddy soils in Fujian province increased by 19 mg·kg-1, with the enriched area reaching 1.22×106 hm2, accounting for 69% of the total paddy soils in Fujian province. Further ecological risk assessment showed that from 2008 to 2018, the area of paddy soil with ecological phosphorus enrichment risk in the province gradually increased, mainly distributed in percogenic paddy soils and hydromorphic paddy soils with a slope of less than 2°. In the future, effective phosphorus fertilizer management measures should be formulated for different types of paddy soil to prevent the occurrence of environmental problems such as water eutrophication.

Dynamic and its driving factors of soil potential acid in croplands of Fujian Province, China.

Soil potential acid is one of the potential factors limiting plant growth, and also an important base in soil acidity regulation. The potential acid and pH value of surface soil samples of cultivated lands in Fujian Province were proportionally selected and measured, and then the optimized relational model between soil pH and potential acid value was fitted. The 1:50 000 databases of cropland soil potential acid in 1982, 2008 and 2016 were established by using the topsoil pH data of 36777, 236445 and 21269 sampling sites collected in 1982, 2008 and 2016 respectively. The dynamics of cropland soil potential acid in Fujian Province and its driving factors were explored by the integrative method of GIS and grey correlation analysis. The results showed that the quantities of soil potential acid in cropland generally increased in Fujian Province from 1982 to 2016. Compared with 1982, the averages of soil potential acid in 2008 and 2016 increased 1.30 and 1.49 cmol·kg-1, respectively. The increase rate of soil potential acid from 1982 to 2008 was 0.03 cmol·kg-1·a-1 higher than that from 2008 to 2016. Meanwhile, the changes of cropland soil potential acid showed significant spatial difference. The change of cropland soil potential acid in Sanming was minimum, and the change in Longyan was maximum, being four times higher than that in Sanming. The change of soil potential acid in different use types of cropland was following the order: paddy field > irrigated land > dry land. The changes of soil potential acid in acid sulfate paddy soils, gleyed paddy soils and submergenic paddy soils were maximum, which were one time higher than the mean change across the whole Province, while the changes in latosolic red earths and salinized paddy soils were minimum, which were 25.7% and 28.4% of the mean change in the Province, respectively. The driving factors for the dynamics of cropland soil potential acid in Fujian Province included the application rates of nitrogen and phosphorus fertilizer, cation exchange capacity (CEC), clay content, pH and silt content, with grey correlation coefficient (absolute value) being higher than 0.92. Accordingly, it would be an effective approach to slow down the increase of cropland soil potential acid in Fujian Province to optimize fertilization management and apply alkaline ameliorant scientifically.

[Responses of fungal community structure and functional group to fertilization in yellow clayey soil.] / 黄泥田土壤真菌群落结构和功能类群组成对施肥的响应.

We investigated the responses and underlying mechanisms of community composition, and function group of fungi in yellow clayey paddy soil to different long-term fertilization, which may provide scientific basis for rational fertilization and sustainable development in agriculture ecosystems. There were four treatments, including control (CK), inorganic fertilizer (NPK), inorganic fertilizer combined with manure (NPKM), and inorganic fertilizer combined with straw (NPKS). Illumina high-throughput sequencing and FUNGuild were performed to investigate the fungal community structure and functional group, respectively. Ascomycota, Basidiomycota, and Zygomycota were identified as the three dominant ones. The proportion of Ascomycota in NPKM and NPKS were significantly lower (49% and 47%, respectively) compared with CK (71%) and NPK (74%) treatments, with the main reduced orders of Hypocreales, Pleosporales and Eurotiales. While there was higher relative abundance of Basidiomycota in NPKM and NPKS (18% and 28%) compared to CK (14%) and NPK (10%), the orders with enhancement were Tremellales, Trechisporales, and Agaricales. The ratio of Basidiomycota was decreased with sole inorganic fertilizer. Moreover, the relative abundance of Zygomycota was increased after 33 years of fertilization, which was dominated by Mortierellales and Basidiobolales at order level. Diversity indices including Shannon, Simpson, Chao1 and ACE were all significantly declined in NPK compared with CK, NPKM and NPKS treatments, whereas Chao1 index and ACE index in NPKM and NPKS were higher than that in CK and NPK. Saprotroph was the main fungal functional group across all the four treatments (48%-57%). Higher proportion of symbiotroph fungi was identified in soils with NPKS and NPKM (17%) in comparison to CK and NPK. The main guilds with the increasing proportion were arbuscular mycorrhizal fungi and ectomycorrhizal fungi. However, significantly higher proportion of animal pathogen fungi were detected in NPK (10%) than other treatments. Redundancy analysis (RDA) showed that moisture, salinity and porosity in soil were more strongly related with fungal community composition and fungal functional composition than soil organic matter and total nitrogen. Our results suggest that sole application of inorganic fertilizer results in great changes in fungal community compositions and the hazard of over production of pathogen fungi, whereas combined organic-inorganic fertilization would be beneficial to maintain the healthy environment through increasing fungal diversity and the ratio of symbiotrophic fungi in yellow clayey paddy soil.

[Effects of soil data and map scale on assessment of total phosphorus storage in upland soils.] / ä¸åŒåˆ¶å›¾å°ºåº¦åŠåœŸå£¤æ•°æ®å¯¹åœŸå£¤å ¨ç£·å‚¨é‡ä¼°ç®—çš„å½±å“.

Accurate assessment of total phosphorus storage in farmland soils is of great significance to sustainable agricultural and non-point source pollution control. However, previous studies haven't considered the estimation errors from mapping scales and various databases with different sources of soil profile data. In this study, a total of 393×104 hm2 of upland in the 29 counties (or cities) of North Jiangsu was cited as a case for study. Analysis was performed of how the four sources of soil profile data, namely, "Soils of County", "Soils of Prefecture", "Soils of Province" and "Soils of China", and the six scales, i.e. 1:50000, 1:250000, 1:500000, 1:1000000, 1:4000000 and1:10000000, used in the 24 soil databases established for the four soil journals, affected assessment of soil total phosphorus. Compared with the most detailed 1:50000 soil database established with 983 upland soil profiles, relative deviation of the estimates of soil total phosphorus density (STPD) and soil total phosphorus storage (STPS) from the other soil databases varied from 4.8% to 48.9% and from 1.6% to 48.4%, respectively. The estimated STPD and STPS based on the 1:50000 database of "Soils of County" and most of the estimates based on the databases of each scale in "Soils of County" and "Soils of Prefecture" were different, with the significance levels of P＜0.001 or P＜0.05. Extremely significant differences (P＜0.001) existed between the estimates based on the 1:50000 database of "Soils of County" and the estimates based on the databases of each scale in "Soils of Province" and "Soils of China". This study demonstrated the significance of appropriate soil data sources and appropriate mapping scales in estimating STPS.