[Soil health evaluation of non-grain cultivated land: A case study of Dongwu Town, Ningbo City, Zhejiang Province, China].

Non-grain utilization of cultivated land threatens farmland ecological environment and soil health, which restricts grain production. To identify the key obstacle factors of cultivated soil under non-grain utilization, explore the changes of soil quality and function, and evaluate the effects of non-grain utilization on the health of farmland soil, we evaluated soil health of farmland under different non-grain utilization types (vegetables, bamboo-abandoned, nursery-grown plant-abandoned, nursery-grown plant-rice) by soil quality index and soil multifunctionality index method combined with sensitivity and resistance approaches. The results showed that soil organic carbon and total nitrogen (TN) in the bamboo-abandoned soil were 95.

[Soil health evaluation of loquat orchard based on soil quality index method].

Fruit quality and yield in orchards will decrease after long-term planting. To analyze the changes of soil quality under different planting years and identify the key factors of the declining of orchard soil quality could provide scientific foundation for optimizing fertilization management of orchard soil. In this study, we analyzed the changes of soil physical, chemical, and biological properties of loquat orchard under different planting years (<10 years, 10-15 years, 15-20 years, ≥20 years) in Ninghai County, Zhejiang Province, and evaluated soil health by using soil quality index, multifunctionality index, and sensitivity and resistance indicators.

[Response of Soil Multifunctionality to Reduced Microbial Diversity].

Soil microbial communities play an important role in driving a variety of ecosystem functions and ecological processes and are the primary driving force in maintaining the biogeochemical cycle. It has been observed that soil microbial diversity decreases with land use intensification and climate change in the global background. It is essential to investigate whether the reduction in soil microbial diversity can affect soil multifunctionality.

[Response Characteristics of Soil Microbial Community Under Long-term Film Mulching].

Film mulching is an important practice to increase the yield and income in agricultural production. Soil samples were collected from four farmland sites with different mulching years to reveal the effect of long-term plastic mulching on characteristics of soil microbial community structure. In order to explore the long-term effect of soil microbial community change and its effect on the microbial ecological environment, high-throughput sequencing technology was used to analyze the changes in soil bacterial and fungal community structure.

[Effect of Long-term Straw Returning on the Mineralization and Priming Effect of Rice Root-carbon].

Long-term straw returning to the field changes the environmental conditions of rice paddy soil, which affects the mineralization and priming effect of residual rice roots in the soil, but the direction and intensity of its influence is not clear. Therefore, based on a long-term fertilization field experiment, C-CO isotopic labeling technology and laboratorial incubation were used to analyze the characteristics of mineralization of rice roots and native soil organic carbon, the intensity and direction of the priming effect, and the source partitioning of CO emissions in three treatments, consisting of no fertilization (CK), chemical fertilizer (CF), and straw returning with chemical fertilizer (CFS). The results showed that after 120 days of flooding incubation, the root residue (R) increased the cumulative CO emissions by 617.

[Effects of Plastic Mulch Film on Soil Nutrients and Ecological Enzyme Stoichiometry in Farmland].

Ecological enzyme stoichiometry can be used to evaluate the limit of soil microbial energy and nutrient resources. To illustrate the effects of plastic mulch film on soil ecological enzyme stoichiometry in farmland, this study collected soil with different amounts of mulching film residual and used the fluorescence analysis to determine the activities of key enzymes for the carbon, nitrogen, and phosphorus cycle processes including -1,4-glycosidase (BG), -1,4-N-acetyl amino glycosidase (NAG), and phosphatase (ACP) activity. This study investigated the effects of plastic mulch film on soil nutrient cycling and supply in farmland.

[Characteristics of Paddy Soil Organic Carbon Mineralization and Influencing Factors Under Different Water Conditions and Microbial Biomass Levels].

Paddy soil often undergoes frequent dry-wet alternation. The change in water status not only affects the physical and chemical properties of the soil, but also changes the structure and diversity of the soil microbial communities, which in turn determines the rate of soil organic carbon mineralization. However, the effects of different water conditions and soil microbial biomass levels on the process of soil organic carbon mineralization and its mechanisms are still unclear.

[Effect of Water Management on Rice Growth and Rhizosphere Priming Effect in Paddy Soils].

The rhizosphere priming effect (RPE) caused by carbon inputs from crop rhizodeposits plays a key role in regulating the carbon emission flux and carbon balance of farmland soils. Due to frequent alternations between dry and wet conditions, CO and CH emissions and the RPE in paddy field ecosystems are significantly different to those of other ecosystems. Therefore, it is of great significance to determine the direction and intensity of the rice RPE under alternations of dry and wet to limit greenhouse gas emissions.

Metagenomic and C tracing evidence for autotrophic microbial CO fixation in paddy soils.

Autotrophic carbon dioxide (CO ) fixation by microbes is ubiquitous in the environment and potentially contributes to the soil organic carbon (SOC) pool. However, the multiple autotrophic pathways of microbial carbon assimilation and fixation in paddy soils remain poorly characterized. In this study, we combine metagenomic analysis with C-labelling to investigate all known autotrophic pathways and CO assimilation mechanisms in five typical paddy soils from southern China.

[Response of Extracellular Enzyme Activities to Substrate Availability in Paddy Soil with Long-term Fertilizer Management].

The availability of carbon (C), nitrogen (N), and other substrates in soil determines the growth and metabolism of microorganisms and affects the activity of extracellular enzymes. To study the activities of -1,4-glucosidase (BG) and -1,4--acetylglucosaminidase (NAG) in response to C and N availability, samples that underwent four treatments-non-fertilization (CK), chemical fertilizer (NPK), combination of organic manure and chemical fertilizer (OM), and mixture of straw and chemical fertilizer (ST)-were collected from long-term fertilization paddy soil and incubated for 0, 4, 8, and 12 months to obtain soil with different C and N availability gradients. The results showed that the dissolved organic carbon(DOC) content of OM and ST treatment samples was 2-3 times higher than that of CK and NPK treatment samples.

[Consumption Capacity of NO in Paddy Soil and the Response Mechanism of -containing Communities].

The long-term flooding anaerobic environment in paddy soils is conducive to denitrification, which is one of the most important reasons for NO emissions. NO can be transformed to nitrogen gas (N) by bacteria and archaea containing nitrous oxide reductase (NOR) encoded by the gene, which is the only known biological pathway of NO consumption in soil. is known to be typical in denitrifying bacteria, which is one of the clades of the gene and is mainly possessed a Tat signal peptide motif.

[Impact of Dicyandiamide (DCD) and 3,4-Dimethylpyrazole Phosphate (DMPP) on Ammonia-oxidizing Bacteria and Archaea in a Vegetable Planting Soil].

Nitrification inhibitors (NIs) dicyandiamide (DCD) and 3,4-dimethylpyrazole phosphate (DMPP) showed significant effects in the inhibition of nitrification and the improvement of the utilization efficiency of nitrogen fertilizer in agricultural soils. However, the effects of different NIs on ammonia-oxidizing bacteria (AOB) and archaea (AOA) is still unclear. To verify the inhibitory effect of DCD and DMPP on AOB and AOA, a pot experiment was performed, including Urea, Urea+DCD, and Urea+DMPP treatments.

[Characterization of Soil Organic Carbon Mineralization Under Different Gradient Carbon Loading in Paddy Soil].

Available carbon is the most active part of the soil carbon pool. It is also the main carbon source of soil microbes and plays an important role in the processes of soil organic carbon mineralization and accumulation. However, the mechanisms are still not clear how soil organic carbon mineralization and its priming effect (PE) are affected by different input levels of readily available carbon, based on the growth requirements of microbes in paddy soil.

[Microbial Carbon Source Metabolic Profile in Rice Rhizosphere and Non-rhizosphere Soils with Different Long-term Fertilization Management].

Rhizosphere and non-rhizosphere soil samples under different long-term fertilization treatments including control without fertilizer (CK), chemical fertilization alone (NPK), rice residues combined with NPK (NPKS), 30% manure plus 70% chemical fertilizers (LOM), and 60% manure plus 40% chemical fertilizers (HOM) were collected from a paddy field in a red soil hilly area in Ningxiang City, Hunan Province, China. The characteristics of microbial carbon utilization in the soils were studied. Results of O-HO tracer analysis showed that both soil microbial biomass carbon content (MBC) and microbial growth rate () were highest in the HOM treatment, whereas they were lowest in CK.

[Allocation and Stabilization Responses of Rice Photosynthetic Carbon in the Plant-Soil System to Phosphorus Application].

This research studied the response of the input and allocation of photosynthetic carbon (C) to phosphorus (P) in paddy soils. Two treatments were conducted in this experiment:no P application (P) and the application of 80 mg·kg of P (P). The rice cultivar was the indica Zhongzao 39.

[Characteristics of amino sugar accumulation in rhizosphere and non rhizosphere soil of rice under different fertilization treatments].

Soil samples were collected from paddy ecosystem under five long-term fertilization treatments, including control without fertilizer (CK), chemical fertilization alone (NPK), rice residue combined with NPK (NPKS), 30% manure plus 70% chemical fertilizer (LOM), and 60% manure plus 40% chemical fertilizer (HOM) in Ningxiang City, Hunan Province. The cha-racteristics of amino sugars accumulation in the rhizosphere and non-rhizosphere soils at rice tillering stage were analyzed. Results showed that the contents of soil organic carbon, total amino sugars and three amino monosaccharides (muramic acid, glucosamine and galactosamine) with long-term application of organic materials (rice residue or manure) were significantly higher compared with CK and NPK.

[Effect of CO Doubling and Different Plant Growth Stages on Rice Carbon, Nitrogen, and Phosphorus and Their Stoichiometric Ratios].

The variation characteristics of ecological stoichiometric ratios can reflect the nature of plant adaptation to environmental changes. The C, N, and P contetns, and their stoichiometric ratios in different organs of rice were studied using a CO continuous labeling system, by simulating the increase of atmospheric CO concentration (800×10). The results showed that CO doubling promoted the growth of rice organs and increased the root/shoot ratio.

[Effects of Varying Long-term Fertilization on Organic Carbon Mineralization and Priming Effect of Paddy Soil].

A laboratory incubation experiment was conducted using the C isotope labeling technique to study the characteristics of organic carbon mineralization and their response to glucose addition when treated with a combination of straw and chemical fertilizer (ST), inorganic fertilizer (NPK), and non-fertilization (CK). The cumulative mineralization rate (ratio of accumulated mineralization amount to total organic carbon content) in CK reaches 1.64% at the end of incubation (56 days).

[Effect of Phosphorus Addition on the Abundance of Autotrophic CO-Fixation Microorganisms in Rhizospheric Soil from a Phosphorus-Limited Paddy Field].

A rice pot experiment was conducted to investigate the effect of phosphorus addition on the abundance of autotrophic CO-fixation microorganisms using phosphorus-limited paddy soil from the Changsha Observation and Research Station for the Agricultural Environment. Rice seedlings were transplanted in the paddy soil with or without phosphorus addition, corresponding to P-treated-pot (P) or control pot (CK), respectively. Rhizosphere soils were collected from the P and CK treatments during the tillering and shooting stages.

[Transformation and Distribution of Soil Organic Carbon and the Microbial Characteristics in Response to Different Exogenous Carbon Input Levels in Paddy Soil].

The turnover of soil organic carbon (SOC) and the activity of soil microbes can be influenced by exogenous carbon. However, microbial response characteristics of the transformation and distribution of available organic carbon under different levels remain unclear in paddy soils. C-labeled glucose was used as a typical available exogenous carbon to simulate indoor culture experiments added at different levels of soil microbial biomass carbon (MBC) (0×MBC, 0.

[Effects of Long-term Fertilization on Enzyme Activities in Profile of Paddy Soil Profiles].

The enzyme activity, which is closely related to soil material cycling (mineralization, transformation, etc.), can reflect soil quality and nutrient status. In order to explore the effect of long-term fertilization on the enzyme activity in paddy soil profile (0-40 cm), soils with organic fertilizer and inorganic fertilizer, and non-fertilized soils were selected, and the carbon and nitrogen contents, and the activities of -1,4-glucosidase (BG), and -1,4--acetylglucosaminidase (NAG) in 10cm depths of soil were analyzed.

[Effects of Long-term Fertilization Regimes on Microbial Biomass, Community Structure and Activity in a Paddy Soil].

Four paddy soils were collected in Ningxiang County, Hunan province. These used with different long-term fertilization regimes, including a control without fertilizer (CK), chemical fertilization with nitrogen, phosphate, and kalium (NPK), straw fertilization combined with NPK (ST), and manure fertilization combinedwith NPK (OM). Phospholipid fatty acid (PLFA) technology and Microresp method were used to study the effect of long-term fertilization on soil microorganism abundance, community structure, and activity.

[Dynamics of Rice Photosynthesized Carbon Input and Its Response to Nitrogen Fertilization at the Jointing Stage: C-CO Pulse-labeling].

Photosynthesized carbon (C) is an important source of soil organic C in paddy fields, and its input and distribution are affected by rice growth and soil fertility. Fertilizer application plays an important role in rice growth. The C pulse-labeling method was used to quantify the dynamics and distribution of input photosynthesized C in the rice-(rhizosphere-and bulk-) soil system and its response to nitrogen fertilizer (N) application.

[Responses of Extracellular Enzymes to Nitrogen Application in Rice of Various Ages with Rhizosphere and Bulk Soil].

Ecological enzyme activities are closely relevant to the carbon and nitrogen decomposition and mineralization of paddy soils, which can reflect the growth and metabolism of microorganisms. In order to clarify the response to nitrogen application by different enzymes in the rhizosphere and bulk soil of rice, the rhizosphere and bulk soil were identified using a rhizosphere bag. In addition, the -1,4-glucosidase (BG) enzyme; -1,4--acetylglucosaminidase (NAG) enzyme; and the effects of the rhizosphere, nitrogen application, and growth period on soil enzyme activities were analyzed.

[Allocation of rice photosynthates in plant-soil system in response to elevated CO and nitrogen fertilization].

To examine the allocation of rice photosynthates and its response to the elevated CO (800 μL·L) and N fertilization (100 mg·kg) at both tillering stage and booting stage in plant-soil system, rice was continually labelled with CO. The results showed that the rice root biomass at the tillering stage and the shoot biomass at the booting stage were significantly increased under elevated CO. Elevated CO increased the rice biomass and root-shoot ratio at tillering stage, but reduced it at booting stage.