摘要：
Biochar and organic fertilizer are widely supported to maintain crop production and sustainable development of agroecosystems. However, it is unclear how biochar and organic fertilizer alone or in combination regulate soil functional microbiomes and their relationships to ecosystem multifunctionality (EMF). Herein, a long-term (started in 2013) field experiment, containing five fertilization treatments, was employed to explore the effects of biochar and organic fertilizer applications on the EMF (based on 18 functional indicators of crop productivity, soil nutrient supply, element cycling, and microbial biomass) and the functional microbiomes of bulk soil and rhizosphere soil [normalizing the abundances of 64 genes related to carbon (C), nitrogen (N), phosphorus (P), and sulphur (S) cycles]. Compared with single-chemical fertilization, biochar and organic fertilizer inputs significantly enhanced most ecosystem-single functions and, in particular, the EMF significantly increased by 18.7-30.1%; biochar and organic fertilizer applications significantly increased the abundances of soil microbial functional taxa related to C-N-P-S cycles to varying degree. The combined application of biochar and organic fertilizer showed a better improvement in these indicators compared to using them individually. Most functional microbial populations in the soil, especially the taxa involved in C degradation, nitrification, nitrate-reduction, organic P mineralization, and S cycling showed significantly positive associations with the EMF at different threshold levels, which ultimately was regulated by soil pH and nutrient availability. These results highlight the strong links between soil microbiomes and agroecosystem functions, as well as providing scientific support for inclusion of biochar in agricultural production and services with organic amendments. 8-year field evidence revealed impacts of biochar and pig manure on soil functional microbiome and ecosystem functions.Biochar and pig manure inputs notably enhanced most ecosystem-single functions and the EMF increased by 18.7-30.1%.Biochar and pig manure inputs notably enriched soil functional microbes related to C-N-P-S cycles to varying degree.Increase in EMF was related to microbe-driven soil processes such as C degradation, nitrification, and Po mineralization.Inclusion of biochar in crop production with organic amendments could enhance agro-ecosystem functions and services.
摘要：
Background and aimsIntercropping is known to have low fertilizer input but high production efficiency. However, only few studies have explored the nutrient stoichiometry of soil and microbiome under intercropping patterns to understand the mechanisms underlying the improvement in crop production by intercropping.MethodsA field-based experiment (started in 2013) was conducted to explore the effects of intercropping of maize with peanut, soybean, gingelly, and sweet potato on soil microbial resource limitation, and the factors controlling the resource limitation were investigated by exploring functional gene abundance and soil C-N-P stoichiometry.ResultsVector angle (indicator of microbial P limitation) was > 45 & DEG; in all soil samples. Compared with monocropping, intercropping significantly decreased the vector length and angle. The RC:N-TERC:N was < 0 and the RC:P-TERC:P was > 0 in all soil samples. The RC:P-TERC:P of the monocropping was significantly higher than that of the intercropping soil. Compared with monocropping, the abundances of most of functional genes related to C degradation and fixation, N fixation, nitrification, denitrification, and P activation increased in intercropping soil. Microbial P limitation was associated more with the C-N-P stoichiometric ratios of soil and microbiome than with functional gene abundance. Soil microbial P limitation was notably related to plant N and P uptake and maize yield, regulating by soil microbial N:P, available P:C and P:N ratio.ConclusionsThis study demonstrated the mitigation of microbial P limitation by intercropping and highlighted the importance of understanding the promotion of microbial metabolisms by soil resource stoichiometry, which can help in improving maize productivity.
关键词：
Intercropping;Soil C pool;Carbon use efficiency;Microbial growth;Microbial diversity;Core microbiota
摘要：
Intercropping is a powerful practice to alter the allocation of photosynthetic carbon (C) to belowground ecosystems via promotion of diversified plant communities. The feedback of soil C stability to intercropping is controlled by microbial C use efficiency (CUE). Despite its significance, there is currently insufficient evidence to decipher how soil microbial CUE reacts to intercropping. By combining a 10-year-long intercropping experiment with a substrate-independent 18O-H2O labelling approach and high-throughput sequencing, we elucidated the performance of intercropping on soil C pool and microbial metabolic traits as well as their relationships with soil microbial communities. Compared with monoculture, maize intercropping with peanut and soybean significantly increased soil C storage, soil mineral-associated organic C (MAOC), soil dissolved organic (DOC), and soil microbial biomass (MBC) contents at maize four growth stages. Soil microbial CUE increased significantly, especially at maize flowering and mature stages, as a consequence of enhanced microbial growth and biomass turnover rate after maize intercropping with peanut and soybean. Soil C storage and accessibility indicators (e.g., MAOC, DOC, and MBC contents) could significantly predict the changes of soil microbial diversity and core taxa. Meanwhile, the beta-diversity (community composition) of soil bacteria, fungi, saprotroph and protists, as well as rare fungal taxa were positively correlated with soil microbial CUE, and these indicators showed a high prediction of the microbial CUE. Soil C storage and accessibility indicators directly and indirectly influenced soil microbial CUE by regulating microbial diversity and key taxa. Soil microbial diversity and core taxa directly and indirectly influenced microbial CUE by mediating microbial respiration, growth, biomass, and enzyme activity, which mediated by soil C storage and accessibility. These findings provide an evidence for the associations between microbial diversity, CUE, and soil C stability, highlighting the importance of intercropping-driven soil microbiome to enhance soil microbial CUE.
摘要：
High crop diversity can potentially enhance farmland productivity and ecosystem services, through direct or indirect effects, particularly belowground. Intercropping is a powerful technique to increase crop diversity and belowground biodiversity. It has attracted long-term global attention. However, little is known about the impacts of belowground microbiota on intercropping-driven increases in crop productivity. This study was an 8 -year experiment involving five maize planting patterns, which aimed to distinguish the contributions of rare and abundant microbiota (bacteria, fungi, and eukaryotes) in rhizosphere soil to support maize production. The results indicated that the richness and phylogenetic diversity of rare microbial taxa were significantly higher than those of abundant taxa across all soil samples. Maize and soybean intercropping increased the diversity of rare taxa rather than abundant taxa. Plant growth stages significantly altered the community composition of both rare and abundant microbial taxa. The assembly of the rare and abundant communities is mainly driven by deterministic processes and, in particular, the abundant taxa rather than the rare taxa mainly contributed to maize productivity gain. The changes in maize productivity were significantly associated with many core species in the abundant microbial communities mainly belonging to bacterial Actinomycetales and Rhodocyclaceae, fungal Tausonia and Curvularia, and eukaryotic Leptophyryidae and Ochromonadaceae. The network complexity of abundant fungi and eukaryotic communities also exerted notable effects on maize productivity. Overall, these findings underscored the importance of the core taxa and network stability of abundant microbiota in intercropping systems. This suggests the potential of intercropping to improve crop production by regulating belowground microbial effects in intensive agroecosystems.
关键词：
Controlled-release nitrogen fertilizer;Double-cropping rice;Nitrogen losses;Nitrogen uptake;Productivity;Soil nitrogen pool
摘要：
Considerable literature has demonstrated the advantage of controlled-release nitrogen (CRN) fertilizer in improving crop productivity. However, few researches have explored the long-term impacts of using CRN fertilizers as alternative to common urea on production and N utilization in double-cropping paddy. To address this gap, our study utilized a database derived from a 10-year field experiment from 2013 to 2022. During early and late rice seasons, compared to common urea (early rice, 150kg hm(-2); late rice, 180kg hm(-2)), CRN fertilizer (150kg hm(-2); 180kg hm(-2)) input significantly increased yield by 7.4%, and 11.7%, as well as N use efficiency (NUE) from 23.0% and 24.6% to 33.0% and 37.5%, respectively. CRN application significantly reduced N losses, evidenced by decrease in runoff (23.1% and 19.4%), leaching (12.7% and 12.1%), ammonia volatilization (28.9% and 30.2%), and N(2)O emissions (10.4% and 16.1%). A reduction of 10% in CRN fertilizer input maintained yield. Compared with normal amount, reducing 10, 20, and 30% CRN input increased NUE by 7.0-7.6%, 7.3-7.4%, and 11.6-12.6%; reduced runoff loss by 16.1-17.9%, 27.9-30.7%, and 35.0-37.2%; decreased leaching loss by 7.6-12.8%, 18.1-22.6%, and 26.5-31.4%; decreased ammonia volatilization by 9.9-12.3%, 16.3-22.7%, and 23.2-29.3%, and decreased N(2)O loss by 7.8-13.3%, 12.8-32.8%, and 20.3-36.9%, respectively. Soils with CRN input showed higher total and inorganic N contents than the soils with common urea, and the content increased in parallel with CRN fertilizer input. Soil N content and N runoff loss were significantly related to yield and N uptake, and N runoff and leaching losses were significantly related to NUE. These results support the sustainable use of CRN fertilizers as a viable alternative to common urea, indicating that application rate of 135 and 162kgN hm(-2) of early and late rice, respectively, maintain yield and enhance N utilization in double-season paddy of southern China.
作者机构：
[Zeng W.; 胡旺; 杨子彧; 张玉平] College of Resources, Hunan Provincial Key Laboratory of Farmland Pollution Control and Agricultural Resources Use, Hunan Agricultural University, Changsha, 410128, China
关键词：
Crop rotation;Rice production;Rhizosphere metabolites;Microbial diversity;Functional microbial population
摘要：
Plants are increasingly revealed to have the ability to shape microbiome composition and function by triggering rhizosphere metabolites. Rotation, a model of crop diversification, promotes crop production by influencing rhizosphere microbiome. However, the rhizosphere metabolites of different rice rotations are rarely reported and, in particular, the regulation of key metabolites on rhizosphere microbiome is unclear. To address this gap, we collected the bulk and rhizosphere soils of four crop rotations (rice-rice, tobacco-rice, rice-oilseed rape, and rice-rice-oilseed rape) to assess rhizosphere metabolites, soil bacterial and fungal diversity, as well as functional microbial populations from a long-term (more than 20 years) field experiment. Compared with the rice-rice system, rhizosphere metabolites, such as deazaflavin, 10-Deacetylbaccatin III, and paclobutrazol, significantly increased in the rice rotation systems with tobacco and oilseed rape. Metabolite components (e.g., azelaic acid, soyasapogenol B, and canrenone) and microbial taxa (Xanthobacteraceae, Bradyrhizobium, and Mortierella) were the keystones regulating the co-occurring correlations of rhizosphere metabolites and soil microorganisms. Compared with the rice-rice, the bulk and rhizosphere soil of rice rotations with oilseed rape or tobacco showed higher abundance of the microbial populations related to C degradation and fixation, N fixation, nitrification, nitrate reduction, inorganic P (Pi) solubilization, and organic P (Po) mineralization. Metabolites, such as 7-chloro-norlichexanthone, daidzein, and soyasapogenol B, were the keystones regulating the co-occurrence relationships of rhizosphere metabolites and functional microbial populations. Rhizosphere metabolite composition was positively related to the populations associated with C fixation and degradation, nitrification, and P solubilization, and negatively related to those associated with methane metabolism, nitrate reduction, denitrification, and anammox (P ≤ 0.05). Soyasapogenol B, daidzei, and [1,1'-biphenyl]− 2,2'-dicarboxylic acid enriched in rotation systems were negatively correlated with dominant microbial taxa such as phylum Bacteroidetes and Chytridiomycota, and positively correlated with phylum Zoopagomycota and the populations associated with key soil functions such as C degradation, nitrate reduction, and P solubilization (P ≤ 0.05). These results demonstrated the importance of rhizosphere metabolites in regulating soil microbiome composition and functional capacity, which deepens understanding of rotations improving rice production via rhizosphere effect.
摘要：
Abundant evidence has demonstrated the feasibility of reducing phosphorus (P) input to face diminishing phosphate rock resources and deteriorating environmental quality in double-cropping paddy. However, the sustainability of reduced P input in the context of maintaining productivity and P efficient utilization is not yet clear. Herein, an 8-year (2013-2021) field-based database was built to explore the effects of reduced P input on rice productivity and the soil-plant P trade-off in double-cropping paddy. In the early and late rice seasons, compared with conventional P fertilization (early rice, 90 kg hm(-2); late rice, 60 kg hm(-2)), the average yield of reduced 10 % P treatment increased by 4.3 % and 2.1 %, respectively; reduced 10-30 % P treatments increased average P use efficiency by 17.1-18.4 % and 14.0-17.2 %, decreased average total P runoff loss by 14.9-33.2 % and 20.8-36.4 %, and decreased average total P leaching loss by 18.5-49.0 % and 24.0-46.1 %, respectively. Compared with conventional fertilization, reduced P fertilizer input by 10 % significantly increased the content of the soil labile-P fraction while reducing that of the soil stable-P fraction. Soil ligand-P and exchangeable-P content decreased with the gradient reduction of P fertilizer input (10-30 %). The main predictors of the change in rice yield and plant P uptake were soil ligand-P and exchangeable-P content, respectively. The dominant predictor of both the P runoff loss and the P activation coefficient was the inorganic P content extracted by NaHCO(3). These findings suggest that reduced P input by 10 % could maintain rice productivity and P use efficiency in the double-cropping paddy, and the transformations between soil P components and increases in P bioavailability may be the key drivers maintaining rice productivity and P utilization under the context of reduced P loading.
作者机构：
[Zhao H.; 王艺哲; 张含丰; 赵杭; 胡旺] College of Resources and Environment/Hunan Provincial Key Laboratory of Farmland Pollution Control and Agricultural Resources Use, Hunan Agricultural University, Changsha, 410128, China;[周旋] Institute of Soil and Fertilizer, Hunan Academy of Agricultural Sciences, Changsha, 410125, China
通讯机构：
[Zhang, Y.-P.] C;College of Resources and Environment/Hunan Provincial Key Laboratory of Farmland Pollution Control and Agricultural Resources Use, China
关键词：
生物炭;南荻;水稻;氨挥发
摘要：
在洞庭湖区农田施用秸秆生物炭不仅能实现秸秆资源化利用,还可降低环境污染压力。本研究于2020年采用水稻盆栽试验,研究了不同南荻秸秆生物炭施用量对土壤氨挥发速率、累积氨挥发量、表面水pH值和NH_4~+-N浓度的影响。供试土壤为第四纪红土发育的红黄泥和花岗岩发育的麻砂泥水稻土,设置6个南荻秸秆生物炭添加处理,即分别以土柱0~ 20 cm土壤重量的0%、1%、2%、4%、6%和8%比例添加生物炭,每盆施用复合肥200 kg N·hm~(-2)。结果表明:施用生物炭导致两种土壤之间或不同生物炭处理之间的氨挥发速率和累积量均存在显著差异。麻砂泥施用生物炭处理在施肥后第2天出现氨挥发峰值,且较不施生物炭处理峰值降低了23.6%~53.4%;红黄泥氨挥发峰值出现在施肥后第7 ~ 13天,且其峰值随着生物炭添加量的增加而升高。整体上,麻砂泥土壤的氨挥发速率均高于红黄泥。麻砂泥土壤<4%生物炭添加量能抑制土壤氨挥发速率及累积量,其中以2%处理降幅最大(46.9%), 但生物炭添加对水稻生长前期表面水pH值的影响不显著;红黄泥土壤随着南荻生物炭用量的增加,表面水中pH值和NH_4~+-N浓度增加,导致氨挥发速率及累积量增幅达1.3~10.5倍。回归分析显示,生物炭添加量是影响两种土壤氨挥发的关键因素。Elovich方程能较好地拟合两种土壤的氨挥发累积量随时间的变化动态,各施炭处理的相关系数均达极显著水平。总体上,对于偏中性的麻砂泥土壤,施用一定量的南荻生物炭对氨排放有一定的抑制作用,而对于酸性的红黄泥土壤,增施南荻生物炭会通过提高表面水的pH值和NH_4~+-N浓度促进氨挥发,因此针对不同类型土壤施用南荻秸秆生物炭应注意选择适宜用量,以降低氮素损失。
作者机构：
[侯坤; 荣湘民; 韩磊; 潘治宇; 彭建伟; 张玉平; 谢桂先; 田昌; 韩永亮] College of Resources and Environment, Hunan Agricultural University, National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources, Changsha, 410128, China
作者机构：
[杨振宇; 罗功文; 赵杭; 胡旺; 王艺哲; 张含丰; 张玉平] College of Resources and Environment, Hunan Agricultural University, National Engineering Laboratory of Soil and Resources Efficient Utilization, Hunan Provincial Key Laboratory of Farmland Pollution Control and Agricultural Resources Use, Hunan Provincial Key Laboratory of Plant Nutrition in Common University, Changsha, 410128, China
作者机构：
湖南农业大学资源环境学院, 农田污染控制与农业资源利用湖南省重点实验室,植物营养湖南省普通高等学校重点实验室, 土壤肥料资源高效利用国家工程实验室,长沙410128;College of Resources and Environment, Hunan Agricultural University, National Engineering Laboratory of Soil and Resources Efficient Utilization, Hunan Provincial Key Laboratory of Farmland Pollution Control and Agricultural Resources Use, Hunan Provincial Key Laboratory of Plant Nutrition in Common University, Changsha 410128, PRC;[李思雨; 杨振宇; 李梦缘; 徐伟; 张玉平] 植物营养湖南省普通高等学校;[尹力初] 湖南农业大学
