Nutrient Cycling In Agroecosystems Research Articles

Efficient anaerobic digestate valorization: Nutrient recovery strategy for enhancing soil fertility in arid agricultural regions

Efficient nutrient cycling in agroecosystems is essential for sustainable agriculture, and the utilization of waste products from various industries can contribute to this process. In this study, we investigated the potential of using anaerobic digestate from food industry waste (sugar beets and food waste) as a nutrient source for fertilizer production. Digestates were sanitized using a mixture of inorganic acids (H2SO4 and H3PO4) or alkaline (KOH), with acidic hydrolysate yielding a higher concentration of amino acids (1981 mg/L) compared to alkaline (186 mg/L). The acidic hydrolysate was centrifuged, and the liquid fraction was used to create a foliar fertilizer. The solid fraction, acidic hydrolysate, sewage sludge incineration ash, and additives (ammonium nitrate, urea with urease inhibitor) were employed to formulate three granular fertilizers. Nitrogen balances were analyzed using Sankey charts for each fertilizer formulation. The highest nitrogen losses (45.90 kg N/1 kg formulation) were recorded in the production of fertilizer containing ammonium nitrate. The fertilizers' effectiveness was evaluated through preliminary wheat germination tests. The highest yields observed for the foliar fertilizer (1% dose) and granular with the addition of urea with a urease inhibitor (20% dose) groups, where fresh sprout mass was approximately 18% and 23% higher than the control, respectively. These findings demonstrate the potential of using anaerobic digestate from food industry waste for nutrient recycling in agroecosystems, contributing to sustainable agriculture.

Temporal dynamics of total and bioavailable fungicide concentrations in soil and their effect upon nine soil microbial markers

Pesticides constitute an integral part of today's agriculture. Their widespread use leads to ubiquitous contamination of the environment, including soils. Soils are a precious resource providing vital functions to society — thus, it is of utmost importance to thoroughly assess the risk posed by widespread pesticide contamination. The exposure of non-target organisms to pesticides in soils is challenging to quantify since only a fraction of the total pesticide concentration is bioavailable. Here we measured and compared the bioavailable and total concentrations of three fungicides – boscalid, azoxystrobin, and epoxiconazole – and evaluated which concentration best predicts effects on nine microbial markers. The experiments were performed in three different soils at five time points over two months employing nearly 900 microcosms with a model plant. The total and bioavailable concentrations of azoxystrobin and boscalid decreased steadily during the trial to levels of 25 % and 8 % of the original concentration, respectively, while the concentration of epoxiconazole in soil nearly remained unchanged. The bioavailable fraction generally showed a slightly faster and more pronounced decline. The microbial markers varied in their sensitivity to the three fungicides. Specific microbial markers, such as arbuscular mycorrhizal fungi, and bacterial and archaeal ammonia oxidizers, were most sensitive to each of the fungicide treatments, making them suitable indicators for pesticide effects. Even though the responses were predominantly negative, they were also transient, and the impact was no longer evident after two months. Finally, the bioavailable fraction did not better predict the relationships between exposure and effect than the total concentration. This study demonstrates that key microbial groups are temporarily susceptible to a single fungicide application, pointing to the risk that repeated use of pesticides may disrupt vital soil functions such as nutrient cycling in agroecosystems.

Positive rhizospheric effects on soil carbon are primarily controlled by abiotic rather than biotic factors across global agroecosystems

The carbon (C) that surrounds the rhizosphere serves as the nexus between soil, plants, and atmosphere. Although it is known that rhizospheric C is sensitive to soil management and environmental changes, the influences of crop roots on rhizospheric C across global agroecosystems have not yet been systematically quantified, which limits our understanding of the terrestrial C cycle. A comprehensive meta-analysis including 748, 294, and 695 paired data of soil organic carbon (SOC), dissolved organic carbon (DOC), and soil microbial biomass carbon (SMBC) in rhizosphere and corresponding bulk soil from 154 papers, together with 25 biotic and abiotic variables, was conducted to quantify the effects of the rhizosphere on soil carbon across global agroecosystems. We found that the rhizosphere had greater SOC, DOC, and SMBC compared to the bulk soil, with 7.0%, 34.6%, and 26.1%, respectively. Rhizospheric effects on SOC and DOC varied significantly with different climate zones, aridity indices, and crop types; however, this phenomenon did not occur with SMBC. Soil available nutrients were the main driving factor behind rhizospheric SOC (relative influence of 37.0%), whereas SMBC played a small role in regulating the rhizosphere DOC, aside from the aridity index, crop type, initial soil C, and soil pH. The soil microbial structure, diversity, and function were not critical for regulating rhizospheric C. Path analysis revealed an intercorrelated network involving climate, physicochemical soil properties, and SMBC to determine the rhizospheric impacts on SOC and DOC. Understanding the size and driving factors of the rhizospheric effects on soil C is useful for determining how crop selection might affect broader C and nutrient cycling in agroecosystems.

Phylogenetic diversity of stochasticity-dominated predatory myxobacterial community drives multi-nutrient cycling in typical farmland soils

Predatory myxobacteria are keystone taxa in the soil microbial food web that potentially regulate soil microbial community structure and ecosystem functions. However, little is known about the community assembly processes of myxobacteria in typical farmland soils over large geographic scales, in addition to their relationship with soil multi-nutrient cycling. Here, we used high-throughput sequencing techniques and phylogenetic null modeling analysis to investigate the distribution patterns and assembly processes of myxobacteria communities, in addition to interactions between myxobacteria communities and soil multi-nutrient cycling. Anaeromyxobacter (28.5 %) and Haliangium (19.6 %) were the dominant myxobacteria genera in all samples, and myxobacteria community similarities exhibited distinct distance–decay relationships. Stochastic processes (~77.8 %) were the dominant ecological processes driving the assembly of predatory myxobacteria communities over large geographical scales and under three fertilization regimes. Myxobacteria community structure was influenced by geographic factors (location and climate), soil factors (soil pH, soil organic carbon, total nitrogen, and total potassium), and fertilization, with myxobacteria community assembly being more sensitive to geographic factors. Organic-inorganic combined fertilization (NPKM) increased the proportions of deterministic processes in myxobacteria community assembly. Moreover, myxobacteria community assembly and diversity were closely associated with soil multi-nutrient cycling. Hence, myxobacteria phylogenetic α-diversity represented by NTI index is a potential bioindicators for soil multi-nutrient cycling. Overall, our findings comprehensively reveal the mechanisms of assembly of myxobacteria communities in soils over large geographic scales, and provide a theoretical basis for further research on the role of predatory bacteria on soil nutrient cycling in agro-ecosystems.

Soil water status shapes nutrient cycling in agroecosystems from micrometer to landscape scales

AbstractSoil water status, which refers to the wetness or dryness of soils, is crucial for the productivity of agroecosystems, as it determines nutrient cycling and uptake physically via transport, biologically via the moisture‐dependent activity of soil flora, fauna, and plants, and chemically via specific hydrolyses and redox reactions. Here, we focus on the dynamics of nitrogen (N), phosphorus (P), and sulfur (S) and review how soil water is coupled to the cycling of these elements and related stoichiometric controls across different scales within agroecosystems. These scales span processes at the molecular level, where nutrients and water are consumed, to processes in the soil pore system, within a soil profile and across the landscape. We highlight that with increasing mobility of the nutrients in water, water‐based nutrient flux may alleviate or even exacerbate imbalances in nutrient supply within soils, for example, by transport of mobile nutrients towards previously depleted microsites (alleviating imbalances), or by selective loss of mobile nutrients from microsites (increasing imbalances). These imbalances can be modulated by biological activity, especially by fungal hyphae and roots, which contribute to nutrient redistribution within soils, and which are themselves dependent on specific, optimal water availability. At larger scales, such small‐scale effects converge with nutrient inputs from atmospheric (wet deposition) or nonlocal sources and with nutrient losses from the soil system towards aquifers. Hence, water acts as a major control in nutrient cycling across scales in agroecosystems and may either exacerbate or remove spatial disparities in the availability of the individual nutrients (N, P, S) required for biological activity.

Metagenomics reveals divergent functional profiles of soil carbon and nitrogen cycling under long-term addition of chemical and organic fertilizers in the black soil region

The long-term effects of different fertilization regimes on the microbial functional potential of soils involving nutrient cycling remain largely unknown. Here, metagenomic sequencing was applied to investigate the influences of long-term chemical and organic fertilization on soil microbial C and N cycling across southern, middle and northern sites of black soil region in Northeast China. The results showed that biogeographic distance induced the most influential on the microbial functional profiles of soil C and N cycling, and significant effects of manure fertilization were detected across three experimental sites. Organic fertilization enriched the relative abundances of Proteobacteria and Planctomycetes that carry C and N cycling genes, while inhibited the growth of oligotrophic groups such as Verrucomicrobia. Chemical fertilization increased the gene abundances involved in methane oxidation, but had little effect on soil C degradation and fixation. Contrarily, manure fertilization, particularly the combination of chemical and organic fertilizers (CFM), significantly decreased the abundance of cooC (reductive acetyl-CoA pathway) and coxS (CO oxidation) while enhanced the abundance of icd (rTCA cycle), which are involved in C fixation. Additionally, chemical fertilization enriched the gene abundance that involved in soil N degradation, nitrification and anammox, whereas manure fertilization was beneficial for the functional potentials of assimilatory and dissimilatory nitrate reductions across the black soils. However, CFM significantly promoted the soil denitrification potential, possibly due to excess N input, which might result in soil N loss via the emission of nitrogenous gas in this region. Furthermore, the substantial enhancement in soil P contents induced by manure addition predominantly affected the C and N cycling profiles, abundance of functional genes and microbial taxa. Moreover, diverse correlations between C and N cycling genes suggested the synergetic or antagonistic interactions of C and N metabolic potentials in the black soils. Overall, this study provided in-depth insights into distinct microbial functional potentials under long-term chemical and organic fertilization that may have predictable consequences for soil nutrient cycling in agroecosystems of black soil region.

Microbial processes and community structure as influenced by cover crop residue type and placement during repeated dry-wet cycles

Soil microorganisms play a critical role in cover crop (CC) residue decomposition and nutrient cycling in agroecosystems. However, the impact of CC residue management and dry-wet cycles on soil and residue microbiota and their potential ecosystem functions is largely unknown. To fill these knowledge gaps, an incubation experiment was conducted with two CC residues, crimson clover (Trifolium incarnatum L.) and cereal rye (Secale cereale L.), and two residue placements (incorporated vs surface-applied). Each CCs by placement treatment was subjected to four dry-wet cycles (20-d each) for a total of 80-d. Crimson clover residues had higher water storage capacities than cereal rye, and the rate at which water was lost from surface-applied CC residues increased after each successive wetting event. Rapid drying of surface-applied CC residues quickly suppressed CO2 fluxes, which increased immediately upon rewetting. Incorporated CC residues maintained water content for longer duration than surface-applied residues and showed greater colonization by soil prokaryotes and saprophytic fungi. Thus, significantly more C and N were mobilized from incorporated residues by 80-d than from surface-applied residues (p < 0.05). Due to differences in residue chemistry, CC residue types have a stronger impact on soil N levels than residue placement. Thus, residue chemistry strongly influenced soil prokaryotic and fungal diversity, community structure, and functionality. While crimson clover-amended soils (N-rich environments) were dominated by copiotrophs, oligotrophs dominated cereal rye-amended soils (N-poor soil environments). On the other hand, residue placement may have a greater effect than residue type in determining residue microbiota, particularly prokaryotes. Based on these findings, we can conclude that the effect of residue placement on C and N mineralization during repeated dry-wet cycles is primarily explained by differences in water dynamics between incorporated and surface-applied CC residues.

Unraveling the toxic effects of iron oxide nanoparticles on nitrogen cycling through manure-soil-plant continuum

Soil contamination with metallic nanoparticles is increasing due to their increased use in industrial and domestic settings. These nanoparticles are potentially toxic to soil microbes and may affect their associated functions and thereby the nutrient cycling in agro-ecosystems. This study examined the effects of iron oxides nanoparticles (IONPs) on carbon (C) and nitrogen (N) dynamics of poultry (PM) and farmyard manure (FYM) in the soil. The application of IONPs increased iron content in soil microbial biomass, which reflected its consumption by the microbes. As a result, colony-forming units of bacteria and fungi reduced considerably. Such observations lead to a decrease in CO2 emission from PM and FYM by 27 and 28%, respectively. The respective decrease fractions in the case of N mineralization were 24 and 35%. Consequently, soil mineral N content was reduced by 16% from PM and 12% from FYM as compared to their sole application without IONPs. Spinach dry matter yield and apparent N recovery were increased by the use of organic waste (FYM, PM). The use of IONPs significantly reduced the plant N recovery fraction by 26 and 24% (P < 0.05) from PM and FYM, respectively. All the results mentioned above lead us to conclude that IONPs are toxic to soil microbes and affect their function i.e., carbon and N mineralization of applied manure, and thereby the on-farm N cycling from the manure-soil-plant continuum.

Long-term residue removal under tillage decreases amoA-nitrifiers and stimulates nirS-denitrifier groups in the soil

No-till in continuous corn (Zea mays L.) production helps to keep an important volume of residues on the soil surface, creating management challenges that could be alleviated by residue removal for bioenergy or animal use. Crop residues, however, are essential to stimulate microbial nutrient cycling in agroecosystems. Thus, both residue removal and tillage options need to be fully evaluated for their impacts on ecosystem services related to soil health, including microbial N cycling. We explored the main steps of the microbial N cycle in relation to soil properties by using targeted gene abundance as a proxy following over a decade of residue removal in continuous corn systems either under no-till or chisel tillage. We used real-time quantitative polymerase chain reaction (qPCR) for the quantification of phylogenetic groups and functional gene screening of the soil microbial communities, including genes encoding critical enzymes of the microbial N cycle: nifH (N2 fixation), amoA (nitrification – ammonia oxidation), nirK and nirS (denitrification – nitrite reduction), and nosZ (denitrification – nitrous oxide reduction). Our results showed that long-term residue removal and tillage decreased soil organic matter (SOM), water aggregate stability (WAS), and the relative abundance (RA) of ammonia-oxidizing bacteria (AOB) carrying nitrifying amoA genes. Denitrifiers carrying nirS genes decreased under no-till as crop residue was removed. In addition, our results evidenced strong correlations among soil properties and phylogenetic groups of bacteria, archaea, and fungi. Overall, this study demonstrated limited but definite impacts of residue management and tillage on the soil environment, which could be exacerbated under less resilient conditions.

Influence of Tillage, Straw-Returning and Mineral Fertilization on the Stability and Associated Organic Content of Soil Aggregates in the North China Plain

Agricultural management, such as tillage and straw-returning, affect soil fertility and nutrient cycling in agroecosystems. With the increasing food demand and challenges imposed by climate change, these effects on soil fertility need to be closely monitored, so that short-term agricultural intensification should not threaten the long-term productivity of the land. Therefore, the main objective of this study was to examine the long-term effects of different management practices on soil aggregate stability and associated organic carbon (OC) and nitrogen (N) over a 33-year period in the croplands of the North China Plain. Bulk soils from the surface and subsurface layers were fractionated using the wet sieving approach. The results showed that the silt + clay (SC) fractions (&lt;0.053 mm) were predominant, accounting for 32–56% of the mass at the 0–20 cm depth, and accounting for 41–55% of the mass at the 20–40 cm depth. Additionally, long-term (33 years) no-tillage management and straw-returning at different application rates increased the mass of large soil macroaggregates (LMA), the LMA- and macroaggregate-associated OC content, but decreased the SC-associated OC content. Mineral N and P fertilizers had a minor effect on the stabilization of soil aggregates. The treatment with straw significantly increased the mean weight diameter (MWD) and geometric mean diameter (GWD), compared with the treatment without straw. Our results indicate that carefully regulated management practices would enhance soil aggregate stability, associated OC and N content in the intensive agroecosystem.

Cover crop effects on soil carbon dioxide emissions in a semiarid cropping system

AbstractCover crops improve soil health and environmental quality by enhancing soil organic carbon (SOC) sequestration and nutrient cycling in agroecosystems. This study evaluated the effect of cover crops on soil CO2–C emissions, temperature, and water content during cover crop growth from April to October, 2017 and 2018. Treatments included fallow, pea (Pisum sativum L.), oat (Avena sativa L.), canola (Brassica napus L.), pea–oat (POmix), pea–canola (PCmix), pea–oat–canola (POCmix), and POC–hairy vetch (Vicia villosa L.)–forage radish (Raphanus sativus L.)–barley (Hordeum vulgare L.) (six species mixture; SSmix). The CO2–C emissions were monitored weekly from April to October each year using a portable infrared‐gas analyzer. Seasonal changes in CO2–C emissions varied with cover crops and peaked as soil temperature and water content following precipitation events. Average CO2–C emissions across sampling dates was 46–70% greater under pea than under fallow, canola, and POmix in 2017, but not different among cover crops in 2018. Although the emissions were higher than fallow, canola and POmix plots had lower CO2–C emissions than other cover crops. Pea as sole cover crop or in mixtures (PCmix, POCmix, SSmix) increased CO2–C emissions and microbial activity whereas canola and POmix mixture reduced the emissions during the period with higher precipitation.

ACCUMULATION POTENTIAL AND NUTRIENT CYCLING OF APPLE OF PERU (Nicandra physalodes)

ABSTRACT Weed residues can influence nutrient cycling in agroecosystems. Quantifying this potential nutrient source may influence weed control and fertilisation practices. Nicandra physalodes (L.) Gaertn. is a weed with a short life cycle and a great ability to accumulate dry matter. Field observations suggest that N. physaloides residues are easily decomposed in soil. The objective of this study was to evaluate the effect of increasing of N, P and K doses on the growth of N. physalodes, as well as the nutrient content, chemical characteristics and C/N ratio of the weed. A randomised block design, arranged in split-plot with three replications, was utilised. The main plots were given four doses of NPK (Dose 1 - 0, 0.3 and 17.2 mg dm-3; Dose 2 - 30, 450.3 and 75.4 mg dm-3; Dose 3 - 60, 900.3 and 133.4 mg dm-3; and Dose 4 - 120, 1800.3 and 249.68 mg dm-3), and the subplots were harvested at ten time points after emergence (26, 33, 40, 47, 54, 61, 76, 91, 106 and 121 days). Higher dry matter production and N, P and K content were observed in plants grown on higher levels of fertiliser. The increase of N, P and K levels in the soil resulted in greater total accumulation of these macronutrients. The highest macronutrient contents were K and N. The treatments did not affect neutral detergent fibre (NDF), acid detergent fibre (ADF) and C/N ratio of plant. N. physalodes had low C/N ratio, low NDF and ADF levels, and great nutrient accumulation, suggesting that this plant is quickly decomposed, providing a rapid cycling of nutrients.

Microbial community structure is affected by cropping sequences and poultry litter under long-term no-tillage

Soil microorganisms play essential roles in soil organic matter dynamics and nutrient cycling in agroecosystems and have been used as soil quality indicators. The response of soil microbial communities to land management is complex and the long-term impacts of cropping systems on soil microbes is largely unknown. Therefore, changes in soil bacterial community composition were assessed in response to cropping sequences and bio-covers at long-term no-tillage sites. Main effects of four different cropping sequences of corn (Zea mays L.), cotton (Gossypium hirsutum L.), and soybean (Glycine max L.) were rotated in four year phases for 12-yrs at two Tennessee Research and Education Centers in a randomized complete block design with split-block treatments of four winter bio-covers: hairy vetch (Vicia villosa L.), wheat (Triticum aestivum L.), poultry litter, and a fallow control. Using Illumina high-throughput sequencing of 16S rRNA genes, bacterial community composition was determined. Composition, diversity, and relative abundance of specific taxa were correlated per cropping system, bio-cover, and their interaction. We found that i) richness and diversity varied temporally and spatially, coinciding with soil carbon, pH, nutrient levels, and climatic variability; ii) community composition varied by cropping system, with continuous corn, soybean, and the corn-soybean rotation presenting a hybrid of the continuous corn and soybean communities; however, continuous cotton resulted in the most varied assemblage; iii) bio-covers asserted the greatest influence on microbial communities; specifically poultry litter treatments differed from cover crops (all of which received inorganic-N). Consequently, microbial diversity was greatest under nutrient rich bio-covers (poultry litter) and high residue producing, less pesticide-intensive cropping sequences (soybean and corn compared to cotton), suggesting a more dynamic soil ecology under these no-till cropping systems. This suggests that nutrient management (inorganic fertilizers vs. animal manure) and greater crop rotations (within 4-yr phases) may directly drive phylogenetic community structure and subsequent ecosystem services across agricultural landscapes.

Nutrient cycling in agroecosystems: Balancing food and environmental objectives

ABSTRACTAs our rapidly growing human population puts great demands on our agricultural production systems, we must promote management practices that balance both food and environmental objectives. We focus this literature review on farm management strategies that tighten nutrient cycles and maintain yields. We examined six metrics for efficient nutrient cycling in agroecosystems: reduced runoff and erosion, reduced leaching, improved soil carbon storage, enhanced microbial biomass, low greenhouse gas emissions, improved water holding capacity, and high yields. We evaluated these metrics in six farm management practices: intercrops, agroforestry, cover crops, organic amendments, integrated crop-livestock, and conservation tillage. Agroforestry and cover crops consistently reduced runoff and erosion and improved carbon sequestration compared to conventional systems. Agroforestry was the only practice that consistently reduced nutrient leaching over conventional practices. Organic amendments and conservation tillage improve water holding capacity. There exists uncertainty in the effectiveness of these practices to reduce nitrous oxide emissions. Finally, although agroforestry tends to suppress yields, all of the practices had either a neutral or positive effect on yields. Evaluating cropping systems in terms of multiple services gives us insight into how to match practices to environmental goals, where the uncertainties lie, and where opportunities exist for improved agroecosystem management.

秸秆还田对耕作黑土中小型土壤动物群落的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 秸秆还田对耕作黑土中小型土壤动物群落的影响 DOI: 10.5846/stxb201511202350 作者: 作者单位: 哈尔滨师范大学地理科学学院,哈尔滨师范大学 地理科学学院,哈尔滨师范大学地理科学学院,哈尔滨师范大学地理科学学院,哈尔滨师范大学地理科学学院,哈尔滨师范大学地理科学学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（41371072，41471037）；黑龙江省普通本科高等学校青年创新人才培养计划（UNPYSCT-2015054）；哈尔滨师范大学校青年学术骨干项目（10XQXG08） Effect of straw-returning management on meso-micro soil fauna in a cultivated black soil area Author: Affiliation: College of Geographical Science,Harbin Normal University,Key Laboratory of Ｒemote Sensing Monitoring of Geographic Environment,College of Heilongjiang Province,,,College of Geographical Science,Harbin Normal University,Key Laboratory of Ｒemote Sensing Monitoring of Geographic Environment,College of Heilongjiang Province,, 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:为了考察秸秆还田对耕作黑土中土壤动物群落结构的影响，2009年到2011年在黑龙江省海伦市进行了定点实验，调查了样地A（17 kg秸秆+含高浓度催腐剂还田）、样地B（8.5 kg秸秆+含低浓度催腐剂还田）、样地C（对照样地），样地D（8.5 kg秸秆还田），样地E（17 kg秸秆还田）的中小型土壤动物群落结构。共获取中小型土壤动物21779只，分别隶属于58个类群。其中，甲螨亚目、姬跳虫科、棘跳虫科与驼跳科4个类群土壤动物在本地区是最适应环境变化的土壤动物类群。土壤动物群落结构分析表明，对照样地C中土壤动物密度最高（46591.67只/m2），土壤动物类群最多（17.17），土壤动物优势度指数最大（0.37），样地D中土壤动物丰富度指数最多（2.63），样地A中土壤动物多样性指数最高（1.72），样地B中土壤动物均匀性最高（0.64）。同时，各样地土壤动物基本都具有表聚性，样地A中土壤动物更趋于生存于上层土壤。综合比较分析表明，样地A秸秆还田方式相对来说最利于土壤动物生存。主成分分析表明，不同秸秆还田方式对土壤动物密度、甲螨亚目动物类群、节跳虫科类群、前气门亚目类群影响较大，是耕作黑土中对秸秆还田方式反应敏感的土壤动物指标，今后可以作为考察耕作黑土秸秆还田肥力效应的评价指标。另外，CAA分析表明：受土壤环境因子影响较大的土壤动物类群多为研究区域内优势类群与常见类群，土壤动物的密度与土壤中有机质、有机碳、碳氮比与全磷的含量关系最为密切。 Abstract:Crop straw is an important material basis for nutrient cycling in agro-ecosystems. Straw returning is a method in which straw is applied to the soil to improve soil properties, and is used for accelerating immature soil development in cultivated land and improving soil fertility. Soil fauna is an important component of the ecosystem, and is involved in the straw decomposition process, improving the decomposition of organic matter and promoting nutrient absorption by plants. Therefore, research on the ecology of soil fauna and sustainable utilization of cultivated soil, including black soil, has been widely conducted. Understanding the correlation between soil fauna and straw returning will provide a scientific basis for the protection of the soil fauna community and sustainable utilization management of tillage ecosystems in black soil areas. To investigate the effect of straw returning on meso-micro soil fauna communities in cultivated black soil, field experiments were carried out in Hai-lun, Heilongjiang Province from 2009 to 2011. The experiments were conducted in five selected plots:Plot A:17 kg corn straw returning and high concentrations of microbial inoculants; Plot B:8.5 kg corn straw returning and low concentrations of microbial inoculants; Plot C:control; Plot D:8.5 kg corn straw returning; and Plot E:17 kg corn straw returning. A total of 21,779 individuals, belonging to 58 groups, were extracted and identified in the plots. Among them, Oribatida, Hypogastruridae, Onychiuridae, and Cyphoderidae were most suitable to understand environmental changes in the study area. Analysis of the soil fauna community structure showed that the density, group number, and Simpson Dominance Index of soil fauna were highest in the control Plot C (46,591.67 ind/m2, 17.17, 0.37, respectively). The soil fauna richness index was highest in Plot D (2.63); the diversity index was highest in Plot A (1.72); and the evenness index was highest in Plot B (0.64). Meanwhile, the soil fauna was characterized by surface accumulation in the experimental plots. The group numbers of dominant soil fauna in Plot A in all soil layers were lower than those in other plots, and soil fauna was more dominant in the upper layer of the soil. Together, the method of straw returning in Plot A was the most productive for soil fauna. In addition, the results of a Principal Component Analysis (PCA) indicated that different methods of straw returning had a considerable effect on soil fauna density. Oribatida, Isotomidae, and Prostigmata were sensitive soil fauna that responded to different methods of straw returning, and could therefore be considered as an evaluating index to investigate the fertility effect of straw returning in cultivated black soil in the future. The results of the Canonical Correspondence Analysis (CCA) indicated that the dominant and common groups of soil fauna were considerably influenced by the soil environment, and the density of soil fauna was closely associated with organic matter, organic carbon, the carbon to nitrogen ratio, and total phosphorus in the soil. 参考文献 相似文献 引证文献

The impact of tillage and chemical management on beneficial arthropods in Mediterranean olive groves

Woodlice (Isopoda: Oniscidae) are known to play important roles in soil profile development and nutrient cycling in agroecosystems. The aim of the present work was to understand the impact of different management regimes on woodlouse fauna in Mediterranean olive groves. The olive groves were located along the Kyrenia mountain range towards the north-west of Cyprus at two different elevations. We used pitfall trapping to compare the abundance of woodlice in groves that were (a) uncultivated at low altitude; (b) uncultivated at high altitude; (c) tilled at low altitude; (d) tilled and chemically managed at low altitude. A total of 1751 woodlice were collected and a significant effect of management regime on the abundance of woodlouse was observed. The low altitude uncultivated olive groves retained a higher number of individuals than the other three management regimes. Our results suggest that tillage alone did not impact severely on woodlouse abundance, but that tillage combined with pesticide and fertiliz...

Effect of nitrogen-sulphur nutrition and inhibitors of nitrification on the yield and quality of maize grain

Effect of nitrogen-sulphur nutrition and inhibitors of nitrification on the yield and quality of maize grain

EFFECT OF WATER AVAILABILITY ON SOIL MICROBIAL BIOMASS IN SECONDARY FOREST IN EASTERN AMAZONIA

Soil microbial biomass (SMB) plays an important role in nutrient cycling in agroecosystems, and is limited by several factors, such as soil water availability. This study assessed the effects of soil water availability on microbial biomass and its variation over time in the Latossolo Amarelo concrecionário of a secondary forest in eastern Amazonia. The fumigation-extraction method was used to estimate the soil microbial biomass carbon and nitrogen content (SMBC and SMBN). An adaptation of the fumigation-incubation method was used to determine basal respiration (CO2-SMB). The metabolic quotient (qCO2) and ratio of microbial carbon:organic carbon (CMIC:CORG) were calculated based on those results. Soil moisture was generally significantly lower during the dry season and in the control plots. Irrigation raised soil moisture to levels close to those observed during the rainy season, but had no significant effect on SMB. The variables did not vary on a seasonal basis, except for the microbial C/N ratio that suggested the occurrence of seasonal shifts in the structure of the microbial community.

Environmental, Social, and Management Drivers of Soil Nutrient Mass Balances in an Extensive Andean Cropping System

Sustainable nutrient cycling in agroecosystems combining grazing and crops has global ramifications for protecting these ecosystems and for the livelihoods they support. We sought to understand environmental, management, and social drivers of nutrient management and sustainability in Andean grazing/crop systems. We assessed the impact of farmer wealth, fields’ proximity to villages, topography, and rangeland net primary productivity (NPP) on mass balances for nitrogen (N), phosphorus (P), and potassium (K) of 43 fields. Wealthier farmers applied greater total amounts (kg) of manure nutrients. However, higher manure application rates (kg ha−1) were associated with field proximity and NPP rather than wealth. Manure P inputs in far fields (> 500-m distant) were half those in near fields. Harvest exports increased with manure inputs (P < 0.001) so that balances varied less than either of these flows. Erosion nutrient losses in steeper far fields matched crop exports, and yields declined with increasing field slope (P < 0.001), suggesting that erosion reduces productivity. Balances for P were slightly positive in near and far fields (+2.2 kg P ha−1 y−1, combined mean) when calculated without erosion, but zero in near fields and negative in far fields with erosion included (−6.1 kg P ha−1 y−1 in far fields). Near/far differences in both inputs and erosion thus drove P limitation. Crop K exports dominated K balances, which were negative even without accounting for erosion. Modeled intensification scenarios showed that remediating far field deficits would require P addition and erosion reduction. Management nested within environmental constraints (NPP, erosion) rather than socioeconomic status drives soil nutrient sustainability in these agroecosystems. Time-lags between management and long-term degradation are a principal sustainability challenge to farming in these montane grazing/crop agroecosystems.

Characteristics of Soil Fauna Communities and Habitat in Small- Holder Cocoa Plantation in South Konawe

The composition of soil fauna community have played an important role in regulating decomposition and nutrient cycling in agro-ecosyste ms (include cocoa plantation). Changes in food availability and conditions in the soil habitat can affect the abundance and diversity of soil fauna. This study aimed: (i) to analyze the pattern of changes in soil fauna community composition and characteristic of soil habitat based on the increasing age of cocoa plantation, and (ii) to identify taxa of soil fauna and factors of soil habitat which differentiate among the cocoa plantations. Sampling of soil, roots and soil fauna was conducted from cocoa plantation aged of 4, 5, 7, 10, and 16 years. Difference in composition of the soil fauna community between ages of the cocoa plantation was significant. Profile of soil habitats was dif fer significantly between the cocoa plantations, except 5 and 7 years aged. A group of soil fauna had relatively limited in its movement, and sensitively to changes in temperature, soil acidity , and the availability of food and nitrogen were taxa differentiating between soil fauna communities. Soil physic-chemical conditions that affected metabolic activity, movement, and the availability of food for soil fauna were a distinguishing factors of the characteristics of the soil habitat between different ages of smallholder cocoa plantations.