TO TALK Research Articles

Correlation between Changes in Soil Properties and Microbial Diversity Driven by Different Management in Artificial Chinese Fir (Cunninghamia lanceolata (Lamb.) Hook.) Plantations

Successive planting is the main pattern for cultivating Chinese fir (Cunninghamia. lanceolata (Lamb.) Hook.). However, the influence of this management has not been totally investigated, especially with respect to the changes in the soil microbial community and the relationship to soil properties. This study investigated the physical and chemical properties of the soil, its enzyme activities, and its microbial diversity in three adjoining plantations managed with different successive planting models (long-term continuous growth without harvest, M1; single harvest cutting followed by the construction of a pure plantation, M2; and double harvest cutting followed by the construction of a mixed plantation, M3) to evaluate the impact of these forest management practices. In most soil layers, M1 was observed to have significantly higher content of Na and Al ions, as well as more polyphenol oxidase (PPO) activity, and M2 had a significantly higher field moisture capacity (FMC) and content of Mg ions, while M3 had significantly higher urease (URE) activity. Changes in the totals of N (TN) and C (TC), alongside the availability of P (AP), C/P, N/P, URE, sucrose (SUC), and PPO values, correlated significantly with bacterial diversity, whereas the dynamics of total K (TK), Na, C/P, N/P, and PPO levels were significantly related to fungal diversity. Among the models, soil bacterial genera, including Burkholderia–Caballeronia–Paraburkholderia, Acidothermus, and Paenibacillus, were mostly affected by TN, TC, AP, organic matter (OM), C/N, C/P, N/P, SUC, and the performance of URE. The distribution of fungal genera in different models showed significant differences. Talaromyces, Trichoderma, and Aspergillus were relatively abundant in M1, while Umbelopsis and Saitozyma exhibited more adaptation in M3. These results illustrated better soil properties and higher abundance of microbial diversity in M1 and M3, and furthermore, demonstrated the strategic benefit of both prolonging the rotation period and of creating mixed artificial plantations to maintain diversity. This study improves the understanding of the impact of a successive planting strategy in C. lanceolata plantation sustainability.

Spatial and temporal variations of soil nutrients of cropland in Northeast China from the 1980s to the 2010s.

In recent years, the degradation of cropland soils in Northeast China, such as "thinned, barren, and hardened", has become increasingly serious, with consequences on sustainable development of agriculture. Based on the data from Soil Types of China (1980s) and Soil Series of China (2010s), we examined the change patterns of soil nutrient conditions across different regions and soil types in Northeast China over the past 30 years through the statistical analysis of large samples. The results showed that: 1) from the 1980s to the 2010s, soil nutrient indicators in Northeast China changed to different degrees. Soil pH decreased by 0.03. Soil organic matter (SOM) content decreasd most prominently, by 8.99 g·kg-1 or 23.6%. Soil total N (TN), total P (TP) and total K (TK) contents showed increasing trends, with increases of 17.1%, 46.8%, and 4.9%, respectively. 2) Changes in soil nutrient indicators differed across different provinces and cities. Soil acidification in Liaoning was the most obvious, with pH decreasing by 0.32. SOM content in Liaoning decreased most significantly, by 31.0%. Soil TN, TP, and TK contents in Liaoning increased most significantly by 73.8%, 248.1% and 44.0%, respectively. 3) The changes of soil nutrients varied greatly among soil types, with brown soil and kastanozems showing the greatest decrease in pH. The SOM content of all soil types showed a decreasing trend, with 35.4%, 33.8% and 26.0% reduction in brown soil, dark brown forest soil and chernozem respectively. The greatest increase in TN, TP and TK contents were observed in brown soil by 89.1%, 232.8%, and 48.5%, respectively. In summary, declining organic matter content and soil acidification were the core problems of soil degradation in Northeast China from the 1980s to the 2010s. Reasonable tillage methods and targeted conservation strategies are critically needed to ensure the sustai-nable development of agriculture in Northeast China.

Organic and Inorganic Amendments Shape Bacterial Indicator Communities That Can, In Turn, Promote Rice Yield.

The dynamic patterns of the belowground microbial communities and their corresponding metabolic functions, when exposed to various environmental disturbances, are important for the understanding and development of sustainable agricultural systems. In this study, a two-year field experiment with soils subjected to: chemical fertilization (F), mushroom residues (MR), combined application of chemical fertilizers and mushroom residues (MRF), and no-fertilization (CK) was conducted to evaluate the effect of fertilization on the soil bacterial taxonomic and functional compositions as well as on the rice yield. The highest rice yield was obtained under MRF. Soil microbial properties (microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), urease, invertase, acid phosphatase, and soil dehydrogenase activities) reflected the rice yield better than soil chemical characteristics (soil organic matter (SOM), total N (TN), total K (TK), available P (AP), available K (AK), and pH). Although the dominant bacterial phyla were not significantly different among fertilizations, 10 bacterial indicator taxa that mainly belonged to Actinobacteria (Nocardioides, Marmoricola, Tetrasphaera, and unclassified Intrasporangiaceae) with functions of xenobiotic biodegradation and metabolism and amino acid and nucleotide metabolism were found to strongly respond to MRF. Random Forest (RF) modeling further revealed that these 10 bacterial indicator taxa act as drivers for soil dehydrogenase, acid phosphatase, pH, TK, and C/N cycling, which directly and/or indirectly determine the rice yield. Our study demonstrated the explicit links between bacterial indicator communities, community function, soil nutrient cycling, and crop yield under organic and inorganic amendments, and highlighted the advantages of the combined chemical and organic fertilization in agroecosystems.

High throughput sequencing-based analysis of the soil bacterial community structure and functions of Tamarix shrubs in the lower reaches of the Tarim River.

Tamarix is a dominant species in the Tarim River Basin, the longest inland river in China. Tamarix plays an important role in the ecological restoration of this region. In this study, to investigate the soil bacterial community diversity in Tamarix shrubs, we collected soil samples from the inside and edge of the canopy and the edge of nebkhas and non-nebkhas Tamarix shrubs located near the Yingsu section in the lower reaches of Tarim River. High throughput sequencing technology was employed to discern the composition and function of soil bacterial communities in nebkhas and non-nebkhas Tamarix shrubs. Besides, the physicochemical properties of soil and the spatial distribution characteristics of soil bacteria and their correlation were analyzed. The outcomes of this analysis demonstrated that different parts of Tamarix shrubs had significantly different effects on soil pH, total K (TK), available K (AK), ammonium N (NH4+), and available P (AP) values (P < 0.05), but not on soil moisture (SWC), total salt (TDS), electrical conductivity (EC), organic matter (OM), total N (TN), total P (TP), and nitrate N (NO3−) values. The soil bacterial communities identified in Tamarix shrubs were categorized into two kingdoms, 71 phyla, 161 classes, 345 orders, 473 families, and 702 genera. Halobacterota, unidentified bacteria, and Proteobacteria were found to be dominant phyla. The correlation between the soil physicochemical factors and soil bacterial community was analyzed, and as per the outcomes OM, AK, AP, EC, and NH4+ were found to primarily affect the structure of the soil bacterial community. SWC, TK and pH were positively correlated with each other, but negatively correlated with other soil factors. At the phyla level, a significantly positive correlation was observed between the Halobacterota and AP, OM as well as Bacteroidota and AK (P < 0.01), but a significantly negative correlation was observed between the Chloroflexi and AK, EC (P < 0.01). The PICRUSt software was employed to predict the functional genes. A total of 6,195 KEGG ortholog genes were obtained. The function of soil bacteria was annotated, and six metabolic pathways in level 1, 41 metabolic pathways in level 2, and 307 metabolic pathways in level 3 were enriched, among which the functional gene related to metabolism, genetic information processing, and environmental information processing was found to have the dominant advantage. The results showed that the nebkhas and canopy of Tamarix shrubs had a certain enrichment effect on soil nutrients content, and bacterial abundance and significant effects on the structure and function of the soil bacterial community.

Effects of long-term straw returning on distribution of aggregates and nitrogen, phosphorus, and potassium in paddy

In order to understand the composition and stability of soil aggregate in paddy filed, as well as the changes of soil aggregate-associated nitrogen (N), phosphorus (P) and potassium (K) after straw addition combined with chemical fertilization, soil samples were collected from a 34-year positioning experiment with three treatments, including no chemical fertilizer (CK), chemical fertilizer only (NPK), and straw addition plus chemical fertilizer (NPKS). The composition of water-stable aggregates at the soil layers of 0-20 cm and 20-40 cm were analyzed with the wet sieving method, as well as the distribution characteristics, contribution rate and activation rate of soil aggregate-associated N, P, and K. Results showed that the fractions of >2 mm and 0.25-1 mm aggregates dominated the soil water-stable aggregates in paddy field, while the contribution of <0.053 mm aggregates was lowest. Compared with CK, NPKS treatment increased the contents of >2 mm and 1-2 mm aggregates at the layers of 0-20 and 20-40 cm, and reduced the contents of 0.053-0.25 mm and <0.053 mm. Similar result in NPK treatment was observed at the layer of 0-20 cm. Compared with tat under the NPK treatment, mean weight diameter (MWD) and geometric mean diameter (GMD) increased by 3.9%-15.5% and 6.3%-41.7% in NPKS treatment, respectively. However, the unstable aggregate index (ELT) reduced by 5.7%-28.7% in the NPKS treatment. NPKS significantly increased the contents of total N (TN), available P (AP), and available K (AK) in soil aggregates, especially in the >0.25 mm aggregates. There were no significant diffe-rences about alkali-hydrolysable N (AN) and total K (TK) between NPK and NPKS treatments. The nutrient contribution of soil aggregates in paddy field was affected by aggregate composition. NPKS significantly increased the contribution of AN, AP, and AK within >1 mm aggregates. In all, straw addition combined with chemical fertilizer could increase the stability of soil aggregates at the layers of 0-20 cm and 20-40 cm, and increase the contents of soil aggregate-associated N, P and K, especially for the >1 mm aggregates. Our results provided insights into ensuring soil quality and sustainable development of resources in paddy field by adjusting the ratio of soil C to N.

Isolation and screening of multifunctional phosphate solubilizing bacteria and its growth-promoting effect on Chinese fir seedlings

Phosphorus-solubilizing microorganisms is a microbial fertilizer with broad application potential. In this study, 7 endophytic phosphate solubilizing bacteria were screened out from Chinese fir, and were characterized for plant growth-promoting traits. Based on morphological and 16S rRNA sequence analysis, the endophytes were distributed into 5 genera of which belong to Pseudomonas, Burkholderia, Paraburkholderia, Novosphingobium, and Ochrobactrum. HRP2, SSP2 and JRP22 were selected based on their plant growth-promoting traits for evaluation of Chinese fir growth enhancement. The growth parameters of Chinese fir seedlings after inoculation were significantly greater than those of the uninoculated control group. The results showed that PSBs HRP2, SSP2 and JRP22 increased plant height (up to 1.26 times), stem diameter (up to 40.69%) and the biomass of roots, stems and leaves (up to 21.28%, 29.09% and 20.78%) compared to the control. Total N (TN), total P (TP), total K (TK), Mg and Fe contents in leaf were positively affected by PSBs while showed a significant relationship with strain and dilution ratio. The content of TN, TP, TK, available phosphorus (AP) and available potassium (AK) in the soil increased by 0.23–1.12 mg g−1, 0.14–0.26 mg g−1, 0.33–1.92 mg g−1, 5.31–20.56 mg kg−1, 15.37–54.68 mg kg−1, respectively. Treatment with both HRP2, SSP2 and JRP22 increased leaf and root biomass as well as their N, P, K uptake by affecting soil urease and acid phosphatase activities, and the content of available nutrients in soil. In conclusion, PSB could be used as biological agents instead of chemical fertilizers for agroforestry production to reduce environmental pollution and increase the yield of Chinese fir.

Long‐term restoration altered edaphic properties and soil microbial communities in forests: evidence from four plantations of southern China

Afforestation has been an important approach to mitigate land deterioration and biodiversity reduction. There are increasing interests in understanding the responses of soil microbial communities under long‐term forest restoration, since they play a crucial role in the mediation of ecosystem functions while interacting with plants. Here we examined the effects of four forests (Acacia species [AM], Eucalyptus species [EE], mixed coniferous species [MC], mixed native broadleaf species [NS]) after 35‐year restoration (1986–2015) on soil environmental factors and soil microbial communities. Our results showed that afforestation significantly increased soil organic carbon (SOC) and total N (TN) while decreasing soil pH. Among the four forest types, there were significant differences for TN and TK (total K) but not for pH, sSOC, and TP (total P). Bacterial species richness and phylogenetic diversity in Acacia forest significantly declined more than those of other forests, but those of fungal communities were remarkably higher in the Acacia forest. Both the bacterial and fungal communities' structure of each forest were strongly related to soil TK and TP. Besides, TK and SOC were primary edaphic properties that respectively affected the distribution pattern of bacterial and fungal communities in four forests. Network structures in AM and MC compared with EE and NS were more complex and closely linked, hence more resistant to extrinsic interference. Our results demonstrate that afforestation altered soil properties and microbial communities during long‐term restoration, which may provide insight into ecological restoration practices and biodiversity maintenance.

Sugarcane/peanut intercropping system improves the soil quality and increases the abundance of beneficial microbes.

Sugarcane/peanut intercropping is a highly efficient planting pattern in South China. However, the effects of sugarcane/peanut intercropping on soil quality need to be clarified. This study characterized the soil microbial community and the soil quality in sugarcane/peanut intercropping systems by the Illumina MiSeq platform. The results showed that the intercropping sugarcane (IS) system significantly increased the total N (TN), available N (AN), available P (AP), pH value, and acid phosphatase activity (ACP), but it had little effect on the total P (TP), total K (TK), available K (AK), organic matter (OM), urease activity, protease activity, catalase activity, and sucrase activity, compared with those in monocropping sugarcane (MS) and monocropping peanut (MP) systems. Both intercropping peanut (IP) and IS soils contained more bacteria and fungi than soils in the MP and MS fields, and the microbes identified were mainly Chloroflexi and Acidobacteria, respectively. Intercropping significantly increased the number of unique microbes in IS soils (68 genera), compared with the numbers in the IP (14), MS (17), and MP (16) systems. The redundancy analysis revealed that the abundances of culturable Acidobacteriaceae subgroup 1, nonculturable DA111, and culturable Acidobacteria were positively correlated with the measured soil quality in the intercropping system. Furthermore, the sugarcane/peanut intercropping significantly increased the economic benefit by 87.84% and 36.38%, as comparedwith that of the MP and MS, respectively. These results suggest that peanut and sugarcane intercropping increases the available N and P content by increasing the abundance of rhizospheric microbes, especially Acidobacteriaceae subgroup 1, DA111, and Acidobacteria.

The application of Bacillus Megaterium alters soil microbial community composition, bioavailability of soil phosphorus and potassium, and cucumber growth in the plastic shed system of North China

The long-term continuous mono-cropping and application of large amount of chemical fertilizers have led to a dramatic degradation of soil quality in the intensive vegetable production system. It is important to develop more sustainable, environmentally friendly and high-efficiency agroecosystems for vegetable production in plastic shed systems. Field experiments were performed to explore the impacts of Bacillus megaterium application on cucumber yields, the bioavailability of soil phosphorus (P) and potassium (K), properties of soil microbial communities in a plastic shed production system with cucumber mono-cropped for more than 15 years. The field trails were set up with four treatments of conventional fertilization as control (CON), conventional fertilization with Bacillus megaterium (CON + BM), conventional fertilization reduced by 10 % P and 10 % (or 5 %) K from chemical fertilizer with Bacillus megaterium (CON + BM - PK1), conventional fertilization reduced by 20 % P and 20 % (or 10 %) K from chemical fertilizer with Bacillus megaterium (CON + BM - PK2). Results illustrated that CON + BM treatment significantly increased the cucumber yields by 11.8 %–15.2 % and P and K accumulation in cucumber fruits and roots by 27.5 %–46.1 % and 17.8 %–45.1 %, respectively. The treatments of CON + BM - PK1 and CON + BM - PK2 did not decrease the yields and quality of cucumber, and the bioavailability of soil P and K compared with CON + BM. Moreover, the strain of Bacillus megaterium can efficiently colonize the soil at the early stage of inoculation and improved the richness of soil bacterial and fungal communities significantly. High-throughput sequencing identified that the application of Bacillus megaterium did not change the compositions of the predominant bacterial phyla Proteobacteria, Acidobacteria, Actinobacteria, Firmicutes, and predominant fungal phylum Ascomycota in soil, but increased the relative abundances of the beneficial bacterial genera and fungal orders and suppressed the development of pathogenic bacterial genus significantly. Principal coordinate analysis revealed that the structures of soil bacterial and fungal communities in the CON + BM treatment were dramatically separated from CON at the early stage of inoculation. Moreover, soil pH, available K (AK), total P (TP), and total K (TK) were dramatically related to the changes of soil bacterial community structure, while soil AK and TK were dramatically linked to the variations of soil fungal community structure. The findings indicated that the application of Bacillus megaterium might contribute to the development of a more sustainable production system of vegetables in plastic shed via improving the properties of soil microbial community and the bioavailability of soil P and K.

The interacting roles and relative importance of climate, topography, soil properties and mineralogical composition on soil potassium variations at a national scale in China

Climatic, topographical and soil conditions are the main drivers of soil potassium (K) variations in terrestrial ecosystem. Although theoretical and empirical studies have explored the single effect of these factors on the variations of soil K, the complex interactions and relative importance of these factors is scarce worldwide and virtually absent for China agricultural ecosystem. Here, the complex interactions and the relative contributions of the environmental variables (climate, topography, key soil properties and clay mineralogical composition) to soil K variations were evaluated in China agricultural soil by using method of structural equation model (SEM). The SEM analyses explained 12.0%, 46% and 28.8% of the variations in soil exchangeable K (EK), nonexchangeable K (NEK) and total K (TK), respectively. The results also showed that climate acted as the most important factor controlling soil K variations, followed by topographical conditions, clay mineralogical composition, and key soil properties. High temperature and precipitation (climate) had directly negative effects on soil K concentrations and the negative effects were strengthened by its impacts on key soil properties and clay mineralogical composition. The effects of topography on soil K concentrations were enhanced by its effects on climate, key soil properties and soil clay mineralogical composition. Soil clay mineralogical composition affected soil K concentrations both directly and indirectly through influencing key soil properties. The unexplained variations in soil K concentrations are due to lack of data related to crop species, finer soil particles content, and the quantity and quality of K inputs. These findings advance the understanding of the patterns and mechanisms driving soil K variations, which is critical for predicting changes in soil nutrients in response to soil forming environment at the global scale.

Formula fertilization of nitrogen and potassium fertilizers reduces cadmium accumulation in Panax notoginseng

ABSTRACTThis study investigated the effect of nitrogen (N) and potassium (K) formula fertilization on cadmium (Cd) accumulation in P. notoginseng. Field investigations as well as formulated N and K fertilizers application experiments were conducted. Field investigations showed that Cd accumulation decreased PNS content in the main roots of P. notoginseng, while PNS content was promoted by soil available potassium (AK) and K in the main roots. The Cd content in P. notoginseng and the bioavailable Cd content in the soil decreased with the increasing of total K (TK) and AK in the soil. The increase of soil pH, total organic matter (TOM) and cation exchange capacity (CEC) values can reduce the bioavailable Cd content in soil, thus reducing the Cd accumulation in P. notoginseng. Under current fertilization in P. notoginseng cultivation, decreased N fertilization can alleviate the deterioration of soil physical and chemical properties. Under identical N fertilization, increasing K fertilization promoted the PNS accumulation (0.3–38.3%), also improved soil physical and chemical properties. Formulated N and K fertilizers application (1:2) experiments showed that reducing application of N and increasing K fertilization could reduce the bioavailable Cd content in soil, and the Cd content also decreased by 0.5–69.6% in P. notoginseng.Abbreviation: PNS: P. notoginseng saponins; F(EXC): Exchangeable fraction; F(Carb): Bound to carbonates fraction; F(Fe-MnOX): Bound to iron and manganese oxides fraction; F(OM): Bound to organic matter fraction; F(RES): Residual fraction; AK: Available potassium; TK: Total potassium; CEC: Cation exchange capacity; TOM: Total organic matter

Effects of enclosing on soil microbial community diversity and soil stoichiometric characteristics in a degraded alpine meadow

Enclosing is an effective rehabilitation measure for degraded pastures that mimics natural recovery of vegetation. To examine the interaction between biotic and abiotic in lightly degraded and enclosing grasslands is helpful for a clear understanding of the structure and function of grassland ecosystem. In this study, soil microbial community and soil stoichiometric characteristics in lightly degraded and 10-year enclosing alpine meadows were studied by high-throughput sequencing and Biolog-Eco methods. The results showed that compared with lightly degraded grassland, the concentration of soil NH4+-N in the enclosing grassland increased significantly, while total K (TK) dramatically decreased. There was no obvious variation in soil total organic carbon (TOC), total N (TN), total P (TP), NO3--N, available P (AP), available K (AK), microbial biomass C (MBC) and microbial biomass N (MBN). The soil microbial biomass C/N was significantly enhanced. The carbon metabolic capabilities of soil microbes in different soil layers of alpine mea-dow were obviously increased with the prolonged incubation time, but there was no significant difference between lightly degraded and enclosed meadows. The OTUs of soil bacteria was significantly higher than that of fungi in alpine meadow. The microbial similarity between lightly degraded and fencing grasslands was 27.0%-32.7%. Enclosing significantly increased the fungal relative richness of Ascomycota, Zygomycetes and Chytridiomycota, while simultaneously decreased the rela-tive abundance of Basidiomycetes. Compared with lightly degraded meadow, the bacterial relative richness of Acidobacteria significantly decreased in enclosing meadow. The community composition of soil fungi and bacteria greatly varied among different soil layers. There was significant difference of fungal community composition in the upper soils between lightly degraded and enclosed grassland. The soil bacterial community diversity was greatly affected by soil TN and AK, while the fungal community diversity was significantly affected by plant aboveground biomass. Soil AK produced great influence on soil microbial carbon source utilization capacity. Generally, long-term grazing exclosure had no significant effects on soil nutrients and soil microbial community diversity of lightly degraded grassland and thus would waste the pasture resources, whereas appropriate grazing could maintain the sustainable utilization of grassland.

Ending composting during the thermophilic phase improves cultivation substrate properties and increasing winter cucumber yield

In the world, 10 billion tons of solid wastes were produced each year. Composting is a better method for solid waste management. Vegetable production now tends to be soilless cultivation. However, completed compost is not suitable for vegetable cultivation. So we studied bagasse (BS), corncobs (CC) and sawdust (SD) as composting materials and investigated stopping in the thermophilic phase for different durations (35, 45, and 65 days). Subsequently, cucumbers were transplanted into nine composted samples mixed with vermiculite at a ratio of 1:1 (v/v). The results obtained during the composting of the three composts (BS, CC and SD) showed that composting for 35 and 45 days increased the root temperature by 1.0–2.2 °C during January and February compared to the effects of composting for 65 days. In addition, microbial community numbers were significantly increased (P < 0.05) by composting for 35 and 45 days compared to those observed when composting for 65 days. Additionally, composting for 35 and 45 days resulted in the highest net leaf photosynthesis rate, total dry matter and cucumber yield among all treatments. Bacterial community numbers, net photosynthesis rate and physico-chemical parameters (bulk density, water-holding porosity, pH, total K (TK) and TOC) had a positive correlation with yield. Therefore, composting for 35 days creates a suitable substrate for cucumber production and facilitates the use of agricultural waste to achieve significant ecological and economic benefits.

Effects of conversion from a natural evergreen broadleaf forest to a Moso bamboo plantation on the soil nutrient pools, microbial biomass and enzyme activities in a subtropical area

Converting natural forests to plantations would markedly change soil physiochemical and biological properties, as a consequence of changing plant vegetative coverage and management practices. However, the effects of such land-use change on the soil nutrient pools and related enzymes activities still remain unclear. The aim of this study was to explore the effects of conversion from natural evergreen broadleaf forests to Moso bamboo plantations on the pool sizes and forms of soil N, P and K, microbial biomass, and nutrient cycling related enzyme activities. Soil samples from four adjacent evergreen broadleaf forest-Moso bamboo plantation pairs were collected from a subtropical region in Zhejiang Province, China. The soil organic C (SOC), total N (TN), total P (TP) and total K (TK) concentrations and stocks and different N, P and K forms were measured, and the microbial biomass C (MBC), microbial biomass N (MBN), microbial biomass P (MBP) and four soil enzymes (protease, urease, acid phosphatase and catalase) were determined. The results showed that converting broadleaf forests to Moso bamboo plantations decreased the concentration and stock of SOC but increased those of TK in both soil layers (0–20 and 20–40 cm), and such land-use change increased the concentration and stock of TN and TP only in the 0–20 cm soil layer (P < 0.05). This land-use conversion increased the concentrations of NH4+-N, NO3−-N, resin-Pi, NaHCO3-Pi, NaOH-Pi, HCl-Pi, available K and slowly available K, but decreased the concentrations of water-soluble organic nitrogen (WSON), NaHCO3-Po and NaOH-Po (P < 0.05). Further, this land-use change decreased the microbial biomass and activities of protease, urease, acid phosphatase and catalase (P < 0.05). In addition, the acid phosphatase activity correlated positively with the concentrations of MBP and NaHCO3-Po, and the activities of urease and protease correlated positively with the concentrations of MBN and WSON (P < 0.01). To conclude, converting natural broadleaf forests to Moso bamboo plantations had positive effects on soil inorganic N, P and K pools, and negative effects on soil organic N and P pools, and on N- and P-cycling related enzyme activities. Therefore, management practices that increase organic nutrient pools and microbial activity are needed to be developed to mitigate the depletion of organic nutrient pools after the land-use conversion.

Effects of fertilization regimes on tea yields, soil fertility, and soil microbial diversity

Fertilization is an important agricultural practice for increasing crop yields and influencing soil properties. A field experiment was conducted in the period of 2006-2011 in southeastern China, to investigate the effects of fertilization regimes on tea (Camellia sinensis [L.] Kuntze) yields, soil chemical properties, and soil bacterial and fungal communities. The field experiment included six treatments: (1) unfertilized control (CON); (2) chemical fertilizers (NPK); (3) half-chemical fertilizers plus half-organic manure (1/2NPKOM); (4) organic manure fertilizers (OM); (5) half-chemical fertilizers plus half-organic manure plus legume stover returned (1/2NPKOM+L), and (6) chemical fertilizers plus legume stover returned (NPKL). Results showed that, compared to the control, NPK treatment showed no significant effect on soil organic matter (SOM), total N (TN), total P (TP), total K (TK), available N (AN), available K (AK) and tea yields, but showed the lowest bacterial Shannon index of 1.714 and the lowest value of 2.002 for fungal Shannon index. Organic manure treatment had the richest diversity of soil bacterial community with Shannon index of 2.542, and the highest levels of soil essential nutrients, including SOM (30.03%), TN (2.90 g kg-1), TP (1.35 g kg-1), AN (245.30 mg kg-1), AP (57.00 mg kg-1), and AK (271.80 mg kg-1), followed by 1/2NPKOM+L, which appeared the maximal tea yields of 6772 kg ha-1. Organic manure amendment was a key factor in determining soil properties and productivity. Base on soil quality and tea yields, both OM and 1/2NPKOM+L treatments were recommended as better choices of fertilization practices for tea soils in southeastern China. These findings provided a better understanding of the importance of fertilizations in promoting soil fertility, crop yields, and altering soil microbial diversity, leading to selection of scientific fertilization practices for sustainable development of agroecosystems.

衡阳紫色土丘陵坡地植被恢复阶段土壤特性的演变

PDF HTML阅读 XML下载 导出引用 引用提醒 衡阳紫色土丘陵坡地植被恢复阶段土壤特性的演变 DOI: 10.5846/stxb201301030012 作者: 作者单位: 湖南环境生物职业技术学院,湖南农业大学生物科学技术学院,湖南环境生物职业技术学院,湖南环境生物职业技术学院,湖南环境生物职业技术学院,湖南环境生物职业技术学院,湖南环境生物职业技术学院 作者简介: 通讯作者: 中图分类号: S154.2；S155.2 基金项目: 湖南省重点项目（62020608001）；湖南省科技厅项目（S2006N332）；湖南省教育厅科学研究项目（12C1057）；湖南省普通高校优秀青年骨干教师培养对象资助项目；湖南环境生物职业技术学院南岳学者基金项目（湘环职院[2012]4号）资助 Changes of soil properties in re-vegetation stages on sloping-land with purple soils in hengyang of Hunan Province, South-central China Author: Affiliation: Hunan Environmental-Biological Polytechnic College,a College of Landscape Architecture,bCentre of Practice and Train,Hengyang,,,,,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:采用空间代替时间序列方法，对衡阳紫色土丘陵坡地不同恢复阶段的土壤理化性质、土壤微生物数量、土壤微生物学性质和主要酶活性特征以及它们之间的相互关系进行研究。结果表明：不同恢复阶段土壤理化特征存在明显差异，从狗尾草群落阶段（Ⅰ）、紫薇-狗尾草群落阶段（Ⅱ）、牡荆+剌槐群落阶段（Ⅲ）到枫香+苦楝-牡荆群落阶段（Ⅳ），0-40cm土壤含水量、容重、非毛管孔隙度、孔隙比、大于0.25mm水稳性团聚体含量、有机碳（SOC）、全氮（TN）、碱解氮（AN）与速效磷（AP）显著增加，土壤容重显著减小，土壤pH值逐渐减小，土壤全磷（TP）、全钾（TK）与速效钾（AK）其差异变化不大，土壤理化特征的差异引起土壤微生物数量、微生物学性质与土壤酶活性的变化；不同恢复阶段土壤微生物总数显著增加，其中细菌数量显著增加，而真菌与放线菌数量显著减少；不同恢复阶段土壤基础呼吸（SBR）、土壤微生物量碳（SMBC）、土壤微生物量氮（SMBN）、土壤微生物量磷（SMBP）、土壤微生物熵（Cmic/Corg）显著增加，而代谢熵或呼吸熵（qCO2）显著减小，碳氮比（C/N）逐渐减小；不同恢复阶段均显著地增加了脲酶（URE）、蔗糖酶（INV）与磷酸酶（APE）的活性；土壤理化性状、土壤微生物数量、土壤微生物学性质与土壤酶活性之间存在密切的相关性。 Abstract:The purpose of the paper was to study the purple soil's physico-chemical characteristics, microbial populations, microbial properties, enzyme activities, and the relationships between them in different stages of re-vegetation on sloping-land in Hengyang of Hunan Province, South-central China. We took soils of 0-40cm depth in typical areas in Setaria viridi community stage (Ⅰ); Lagerstroemia indica-Setaria viridi community stage (Ⅱ); Vitex negundo var. cannabifolia+Robinia pseudoacacia community stage (Ⅲ); and Liquidamdar formosana+Melia azedarach-Vitex negundo var. cannabifolia community stage (Ⅳ) as our test objects by using the space series to replace time courses.The results showed that: (1) From Ⅰ, Ⅱ, Ⅲ to Ⅳ, the soil water content, total soil porosity, ratio of non-capillary porosity to capillary porosity, >0.25mm water stable aggregates content, SOC (Soil Organic C), TN (Total N), AN (Available N) and AP (Available P) increased significantly. In contrast, soil bulk density decreased significantly, pH decreased slightly, and there were no significant differences in TP (Total P), TK (Total K) and AK (Available K). The changes in the number of soil microbes, microbial properties and the soil enzyme activities have resulted from the differences in the soil physico-chemical characteristics. (2) The number of soil microbes increased significantly, with a significant increase in the number of bacteria, but the numbers of fungi and actiomycetes decreased significantly in the process of the succession. (3) The SBR (Soil Base Respiration), SMBC (Soil Microbial Biomass C), SMBN (Soil Microbial Biomass N), SMBP (Soil Microbial Biomass P) and Cmin/Corg increased significantly. The qCO2 decreased significantly, and C/N decreased, with no significant difference in the process of succession. The activities of URE (Urease), INV (Invertase) and APE (Alkaline phosphatase) significantly increased in the process of the succession. (4) There were close correlations among the soil physico-chemical characteristics, the number of soil microbes, the soil microbial properties and the soil enzyme activities. This study will, to some degree, enrich the restoration ecology of this area and provide a theoretical basis for the re-vegetation and reconstruction of ecosystems on sloping land with purple soils in Hengyang of Hunan Province, South-central China. 参考文献 相似文献 引证文献

Application of matter-element model in soil nutrient evaluation of ecological fragile region

On the basis of the soil environment investigation in Da’an City, Jilin Province, China, 40 soil samples from main land use types were obtained and tested by standard method. Soil organic matter (SOM), total N (TN), total P (TP), total K (TK), available N (AN), available P (AP) and available K (AK) were chosen as the evaluation factors. A regional soil nutrient evaluation model was developed based on the matter-element model. The results show that the soil samples with nutrient grade II–V respectively account for 10%, 30%, 32.5% and 27.5%, and those with grade IV and V account for 60% in all samples. The relationship between soil nutrients and land types indicates that the nutrients of farmland are relatively good, with 41.7% of soil samples with the nutrient grade IV and V. The nutrients of saline-alkali land and sandy land are the worst, with 100% of soil samples with the nutrient grade IV and V. And the ratios of soil samples grade IV and V in grassland and wasteland are respectively 62.5 % and 54.55%. Generally speaking, the soil nutrients status in Da’an City is poor, 60% of soil samples are in poor and extremely poor conditions, indicating that the soil has been severely eroded. Being a relatively superior evaluation method with more accurate results and spatial distribution consistency, matter-element analysis is more suitable for regional soil nutrient evaluation than previous models.

Application of Geo-Information Technology in the Study of Soil and Nutrients Loss by Water Erosion for three Different Land Cover

This research integrated the Revised Universal Soil Loss Equation (RUSLE) and the soil statistical analysis with RS and GIS techniques to quantify soil and nutrient loss risk. The Letianxi watershed, located in the southwest part of Hubei Province of China was taken as a case. A system was established for rating soil erodibility, slope length/gradient, rainfall erosivity and conservation practices. The rating values serve as inputs into a Revised Universal Soil Loss Equation (RUSLE) to calculate the risk for soil degradation processes, namely soil water erosion. Two Landsat TM senses in 1997 and ETM 2002, respectively, were used to produce land use/cover maps of the study area based on the maximum likelihood classification method. These maps were then used to generate the conservation practice factor in the RUSLE. In order to assess the effect of land cover and landscape position on soil nutrient consisting of Soil Organic Mater (SOM), Total N (TN), Total P (TP) and Total K (TK), soil samples were collected from the top to foot of hill slope in the study area. The three categories consisted of a typical land cover structure for each polygon in the study area: Soil under forest cover (T1), soil under agriculture crops cover (T2) and soil under no vegetation cover (T3). Annual loss of total N (8.24 kg ha?1), total P (5.88 kg ha?1) and total K (6.98 kg ha?1), per unit loss of soil (t ha?1), was maximum from the soil under no vegetation cover (T3). The loss of total N ranged between 5.30 and 32.27 kg ha?1, total P ranged between 2.14 and 12.42 kg ha?1, total K ranged from 2.12 to 10.31 kg ha-1 whereas organic matter loss varied between 10.65 and 236.16 kg ha-1, from three different land covers. ERmapper and Arc/Info software were used to manage and manipulate thematic data, to process satellite images and tabular data source. Results showed that 110.72 km2 (27.09%) was exposed to very slight soil loss and 227.01 km2 (55.55%) was exposed to slight soil loss. This study demonstrates the effectiveness of Geo-information technology in generating a soil and nutrient loss map.