Unexpected Diversity in Ecosystem Nutrient Responses to Experimental Drought in Temperate Grasslands

The responses of ecosystem nitrogen (N) and phosphorus (P) to drought are an important component of globalchange studies. However, previous studies were more often based on site-specific experiments, introducing a significantuncertainty to synthesis and site comparisons. We investigated the responses of vegetation and soil nutrientsto drought using a network experiment of temperate grasslands in Northern China. Drought treatment (66%reduction in growing season precipitation) was imposed by erecting rainout shelters, respectively, at the driest,intermediate, and wettest sites. We found that vegetation nutrient concentrations increased but soil nutrient concentrationsdecreased along the aridity gradient. Differential responses were observed under experimentaldrought among the three grassland sites. Specifically, the experimental drought did not change vegetation andsoil nutrient status at the driest site, while strongly reduced vegetation but increased soil nutrient concentrationsat the site with intermediate precipitation. On the contrary, experimental drought increased vegetation N concentrationsbut did not change vegetation P and soil nutrient concentrations at the wettest site. In general, the differentialeffects of drought on ecosystem nutrients were observed between manipulative and observationalexperiments as well as between sites. Our research findings suggest that conducting large-scale, consistent, andcontrolled network experiments is essential to accurately evaluate the effects of global climate change on terrestrialecosystem bio-geochemistry.

Litter production and leaf nutrient concentration and remobilization in response to climate seasonality in the central Amazon

Litterfall is the largest source of nutrients to for-est soils of tropical rainforests.However,variability in lit-terfall production,nutrient remobilization,and changes in leaf nutrient concentration with climate seasonality remain largely unknown for the central Amazon.This study meas-ured litterfall production,leaf nutrient remobilization,and leaf area index on a forest plateau in the central Amazon.Litterfall was measured at monthly intervals during 2014,while nitrogen,phosphorus,potassium,calcium and mag-nesium concentrations of leaf litter and canopy leaves were measured in the dry and rainy seasons,and remobilization rates determined.Leaf area index was also recorded in the dry and rainy seasons.Monthly litterfall varied from 33.2(in the rainy season)to 87.6 g m^(-2) in the dry season,while leaf area index increased slightly in the rainy season.Climatic seasonality had no effect on concentrations of nitrogen,calcium,and magnesium,whereas phosphorous and potassium responded to rainfall seasonality oppositely.While phosphorous increased,potassium decreased during the dry season.Over seasons,nitrogen,potassium,and phosphorous decreased in leaf litter;calcium increased in leaf litter,while magnesium remained unaffected with leaf aging.Regardless,the five nutrients had similar remobilization rates over the year.The absence of climate seasonality on nutrient remobilization suggests that the current length of the dry season does not alter nutrient remobilization rates but this may change as dry periods become more prolonged in the future due to climate change.

A test of the mycorrhizal-associated nutrient economy framework in two types of tropical rainforests under nutrient enrichments

Shifts in tree species and their mycorrhizal associations driven by global change play key roles in biogeochemical cycles. In this paper, we proposed a framework of the mycorrhizal-associated nutrient economy(MANE), and tested it using nutrient addition experiments conducted in two tropical rainforests. We selected two tropical rainforests dominated by arbuscular mycorrhizal(AM) and ectomycorrhizal(ECM) trees, and established eighteen20 m×20 m plots in each rainforest. Six nitrogen(N) and phosphorus(P) addition treatments were randomly distributed in each rainforest with three replicates. We examined the differences in soil carbon(C) and nutrient cycling, plant and litter productivity between the two rainforests and their responses to 10-year inorganic N and P additions. We also quantified the P pools of plants, roots, litter, soil and microbes in the two rainforests. Overall,distinct MANE frameworks were applicable for tropical rainforests, in which soil C, N and P were cycled primarily in an inorganic form in the AM-dominated rainforest, whereas they were cycled in an organic form in the ECMdominated rainforest. Notably, the effects of mycorrhizal types on soil P cycling were stronger than those on C and N cycling. The intensified N and P deposition benefited the growth of AM-dominated rainforests instead of ECMdominated rainforests. Our findings underpin the key role of mycorrhizal types in regulating biogeochemical processes, and have important implications for predicting the ecological consequences of global changes.

Growth efficiency,intestinal biology,and nutrient utilization and requirements of black soldier fly(Hermetia illucens)larvae compared to monogastric livestock species:a review

In recent years,interest in the larvae of black soldier fly(BSF)(Hermetia illucens)as a sustainable protein resource for livestock feed has increased considerably.However,knowledge on the nutritional and physiological aspects of this insect,especially compared to other conventional farmed animals is scarce.This review presents a critical comparison of data on the growth potential and efficiency of the BSF larvae(BSFL)compared to conventional monogastric livestock species.Advantages of BSFL over other monogastric livestock species includes their high growth rate and their ability to convert low-grade organic waste into high-quality protein and fat-rich biomass suitable for use in animal feed.Calculations using literature data suggest that BSFL are more efficient than broilers,pigs and fish in terms of conversion of substrate protein into body mass,but less efficient than broilers and fish in utilization of substrate gross energy to gain body mass.BSFL growth efficiency varies greatly depending on the nutrient quality of their dietary substrates.This might be associated with the function of their gastrointestinal tract,including the activity of digestive enzymes,the substrate particle characteristics,and their intestinal microbial community.The conceived advantage of BSFL having an environmental footprint better than conventional livestock is only true if BSFL is produced on low-grade organic waste and its protein would directly be used for human consumption.Therefore,their potential role as a new species to better close nutrient cycles in agro-ecological systems needs to be reconsidered,and we conclude that BSFL is a complementary livestock species efficiently utilizing organic waste that cannot be utilized by other livestock.In addition,we provide comparative insight into morpho-functional aspects of the gut,characterization of digestive enzymes,gut microbiota and fiber digestion.Finally,current knowledge on the nutritional utilization and requirements of BSFL in terms of macro-and micronutrients is reviewed and found to be rather limited.In addition,the research methods to determine nutritional requirements of conventional livestock are not applicable for BSFL.Thus,there is a great need for research on the nutrient requirements of BSFL.

Biomass production,nutrient cycling and distribution in age-sequence Chinese fir(Cunninghamia lanceolate)plantations in subtropical China

Biomass production and nutrient （N, P, K, Ca and Mg） accumulation, distribution and cycling were quantified in young, mature and over-mature （10-, 22-, and 34-year old） Chinese fir [Cunninghamia lanceolate （Lamb.） Hook] plantations in southern China. Total stand biomass of young, mature and over-mature stands was 38, 104 and 138 t ha-1 respectively. Biomass production increased significantly with age. Stem wood represented the highest percentage of stand biomass, accounting for 41, 55 and 63 % in the young, mature and over-mature plan- tations respectively. Nutrients concentration was highest in live needles and branches, and lowest in stem wood. The plantations accumulated more N, followed by K, Ca, Mg, and P. Nutrient return amount, nutrient utilization effi- ciency, nutrient turnover time, the ratio of nutrient return and uptake increased with stand age, which implies that young Chinese fir deplete soil nutrients to maintain growth, and efficiently utilize nutrients to decrease dependence on soil nutrients as they age. Harvesting young Chinese fir plantations would therefore lead to high nutrient loss, but prolonging the rotation length could improve soil recovery, and help sustain productivity in the long-term. Improved nutrient return through litterfall as stands get older may also be beneficial to nutrient pool recovery.

Productivity and nutrient cycling in an agroforestry ecosystem for interplant of pineapple and coconut

In this paper, the biomass productivity and nutrient cycling in an agroforestry system of coconut (Cocus nucifera) interplanted with pineapple (Ananas comosus) had been studied. The result showed that the biomass productivity of this ecosystem was 47 460 kg...hm2...a?1, which was 4.3 times as much as that of pure coconut plantation. In the biological cycling of N, P. K elements, the total annual retention was 559.470 kg...hm?2, the annual return was 410.745 kg...hm?2, the annual uptake was 970.475 kg...hm?2, respectively. The average circulation rate in three nutrient elements (N, P, K) was 42.32%, which was 27.53% more than that in pure coconut stands. Coconut interplanted with pineapple was proved to be one of optimum cultural patterns, which had the higher biomass productivity, and better usage efficiency of environment resources in tropical areas.

Decreasing nutrient concentrations in soils and trees with increasing elevation across a treelineecotone in Rolwaling Himal, Nepal

At a global scale, tree growth in alpine treeline ecotones is limited by low temperatures. At a local scale, however, tree growth at its upper limit depends on multiple interactions of influencing factors and mechanisms. The aim of our research was to understand local scale effects of soil properties and nutrient cycling on tree growth limitation, and their interactions with other abiotic and biotic factors in a near-natural Himalayan treeline ecotone. Soil samples of different soil horizons, litter, decomposition layers, and foliage samples of standing biomass were collected in four altitudinal zones along three slopes, and were analysed for exchangeable cations and nutrient concentrations, respectively. Additionally, soil and air temperature, soil moisture, precipitation, and tree physiognomy patterns were evaluated. Both soil nutrients and foliar macronutrient concentrations of nitrogen(N), magnesium(Mg), potassium(K), and foliar phosphorus(P) decrease significantly with elevation. Foliar manganese(Mn) concentrations, bycontrast, are extraordinarily high at high elevation sites. Potential constraining factors on tree growth were identified using multivariate statistical approaches. We propose that tree growth, treeline position and vegetation composition are affected by nutrient limitation, which in turn, is governed by low soil temperatures and influenced by soil moisture conditions.

Changes in ecological stoichiometry and nutrient resorption in Castanopsis hystrix plantations along an urbanization gradient in the lower subtropics

The stoichiometry of carbon,nitrogen and phosphorous in plants can reflect the interactions between plants and their environment.The interplay between plant nutrients,climatic factors,and soil properties and the underlying regulatory mechanisms are pillars of ecology but remain underexplored.In this study of plant C-N-P stoichiometry and nutrient resorption in Castanopsis hystrix groves in three cities(Guangzhou,Zhongshan,and Lechang)that represent an urban-rural gradient in Guangdong Province,South China,we explored potential relationships among NO_(2) concentrations,diameter at breast height(DBH),and resident human population.Mean annual temperature,mean annual precipitation,insolation duration per year,and the human resident population differed significantly among the three cities.Soil C-N-P was always highest in suburban Lechang,and the concentration of NO_(2) was highest in urban Guanghzou(55.33±0.67μg m^(-3))and positively correlated with the resident population and leaf N:P.Our findings suggest that C-N-P stoichiometry of C.hystrix was better explained by NO_(2)than by soil C-N-P stoichiometry and that nutrient resorption was better explained by leaf nutrients and DBH than by NO_(2) and soil stoichiometry.Our study supports the hypothesis that rapid urbanization influences NO_(2) concentrations and microclimate,which may jointly change the stoichiometry of plant nutrients in the forest ecosystems.

Importance of overstorey attributes for understorey litter production and nutrient cycling in European forests

Background:In contrast with the negligible contribution of the forest understorey to the total aboveground phytobiomass of a forest,its share in annual litter production and nutrient cycling may be more important.Whether and how this functional role of the understorey differs across forest types and depends upon overstorey characteristics remains to be investigated.Methods:We sampled 209 plots of the FunDivEUROPE Exploratory Platform,a network of study plots covering local gradients of tree diversity spread over six contrasting forest types in Europe.To estimate the relative contribution of the understorey to carbon and nutrient cycling,we sampled non-lignified aboveground understorey biomass and overstorey leaf litterfall in all plots.Understorey samples were analysed for C,N and P concentrations,overstorey leaf litterfall for C and N concentrations.We additionally quantified a set of overstorey attributes,including species richness,proportion of evergreen species,light availability(representing crown density)and litter quality,and investigated whether they drive the understorey’s contribution to carbon and nutrient cycling.Results and conclusions:Overstorey litter production and nutrient stocks in litterfall clearly exceeded the contribution of the understorey for all forest types,and the share of the understorey was higher in forests at the extremes of the climatic gradient.In most of the investigated forest types,it was mainly light availability that determined the contribution of the understorey to yearly carbon and nutrient cycling.Overstorey species richness did not affect the contribution of the understorey to carbon and nutrient cycling in any of the investigated forest types.

Nutrient cycling characteristics of Quercus acutisima and Pinus massoniana mixed forest in the Three Gorge Reservoir area, China

The cycling characteristics of nitrogen(N), phosphorus(P) and potassium(K) of the Quercus acutissima and Pinus massoniana mixed forest which is the most common forest type in the Three Gorge Reservoir areas in China, were systematically analyzed. The results showed that N, P and K accumulated in the plant pool and in the litter pool, while total N, P, and K were deficient in the soil pool and in the forest systems. Contents of N in the soil of depth 20—40 cm were the key factor limiting growth of trees. The biological outside cycling coefficients were 878, 725 and 117 times of inside cycling coefficients of N, P and K, respectively. 3392, 1026 and 1588 kg of N, P and K return to the litter pool from branches, leaves and throughfall per year, but, 1431, 132 and 1048 kg of N, P and K return to the soil from litter pool per year respectively. It is clear that 58% of N, 87% of P, and 34% of K are lost by surface runoff per year. 549%, 130%, and 834% of N, P and K withdraw from leaves to branches, 499%, 199% and 730% of N, P and K withdraw from branches to trunks per year, respectively.

Nutrient Export with Logs, and Release from Residues, after Harvest of a <i>Pinus taeda</i>Plantation in Uruguay

In Uruguay, Pinus taeda is usually planted a few months after harvest of the former turn, therefore;decomposing residues represents a nutrient source for the new plantation. The aim of this study was to determine the biomass and nutrient extraction off site, following the harvest of a P. taeda plantation. Residue decomposition patterns, and nutrient release were also examined. The site will be referred as S1, corresponding to the clear cut of a 22-year-old P. taeda plantation. Before the clear cut 10 trees were harvested, and logs, branches, twigs, and needles separately weighed. Additionally, forest litter at harvest time was quantified in three different areas. To assess decomposition, mesh bags with residues were allocated in three areas over the forest litter, and samples were taken periodically for 26 months. The remaining biomass, N, P K, Ca, and Mg contents were determined in the different fractions, calculating decompositon rates. Most of the harvested biomass was removed in logs, but the proportion of nutrients exported was considerably lower. Needles showed the highest biomass loss and only 39.1% remained after 26 months, while branches presented high rates in the first two months after cut, but slower thereafter, and at the end of the study more than two thirds of the woody residues remained. Potassium was rapidly released from the residues, while Ca, and Mg, were slowly released, and there was evidence of N and P immobilization in the early stages of decomposition. It was concluded that, although a lower proportion of nutrients were exported, compared to biomass, in the long term, nutrient export with logs could be significant for the sustainability of this production system. While K release from residues did not depend on biomass decay, the slow decomposition, and release of the other nutrients, indicates that this process could have been delayed by nutrient scarcity.

Impact of black cherry on pedunculate oak vitality in mixed forests:Balancing benefits and concerns

The vitality of European forests continues to decline due to new pests and diseases,climate-change related disturbances and high loads of atmospheric nitrogen deposition.Deteriorating soil health is a major factor underpinning the low vitality of West-European forests.Selecting tree species with soil ameliorative traits is proposed as an avenue to counteract soil acidification and improve overall forest vitality.Here we evaluate the impact of black cherry(Prunus serotina Ehrh.),a known rich litter species,on the vitality of neighboring pedunculate oak(Quercus robur L.)in ten mixed forests on sand in Germany,Belgium and the Netherlands.We found that black cherry admixture increases foliar N and P to a surplus whereas it causes deficiencies in foliar Mg,thereby resulting in an overall negative effect on oak foliar nutrient concentrations.Contrary,defoliation of oak leaves by herbivory decreases with the proximity of black cherry.Using structural equation modelling(SEM),we tested the hypothesized‘improved soil health’pathway.Our analyses showed that black cherry admixture leads to lower accumulation in the humus layer,resulting in higher soil base saturation which has a positive effect on foliar Ca yet a negative effect on total chlorophyll.Moreover,the SEM illustrated that herbivory of oak leaves decreases when black cherry is admixed,both via dilution and improved soil health.Indirect effects of black cherry on oak vitality via“improved soil health”in our SEM are however small in comparison to direct relations.Hence,our study showed that the combined positive and negative impacts of black cherry on oak vitality are limited,which tempers the potential benefits of using the rich litter species to counteract oak decline via improved soil health–yet,the concern of black cherry as an invasive alien species negatively affecting the vitality of mature pedunculate oak trees may also be exaggerated.

Litter removal impacts on soil biodiversity and eucalypt plantation development in the seasonal tropics

The little layer of tree plantations provides primary nutrients for uptake,buff ers changes in soil moisture,and provides habitat and substrate to soil epigeic fauna.However,this layer in eucalypt plantations is often removed to reduce fuel load during the fi re season in the Brazilian savanna(Cerrado).Therefore,it is necessary to quantify the eff ects of changes in litter dynamics on the function of these plantations,on key nutrient cycling processes and on epigeic fauna diversity and abundance.In two adjacent stands(one juvenile and one mature),the consequences of two years of litter removal were quantifi ed as monthly litterfall,leaf and fi ne wood litter decomposition,epigeic fauna abundance and diversity,soil biogeochemical variables,and tree diameter and basal area increments.Monthly litterfall rates in juvenile and mature stands did not change with litter removal over the study period.Annual litterfall ranged from 4.1 to 4.9 Mg ha^(−1)a^(−1)in litter removal plots and from 3.9 to 4.8 Mg ha^(−1)a^(−1)in control plots.Fine wood litter decomposition was slower in litter removal plots compared to controls,while leaf decomposition rates were similar in both.Two years of litter removal in the juvenile stand did not aff ect topsoil biogeochemical parameters but decreased available phosphorus at 20–40 cm depth relative to controls.In the mature stand,total cation exchange capacity(0–20 cm)was higher in controls(6.4 cmol c dm^(−3))relative to litter removal plots(6.3 cmol c dm^(−3)),while soil moisture(0–40 cm depth)was lower in litter removal(25.45 m 3 m^(−3))compared to control plots(26 m^(3)m^(−3))in the dry season.A non-metric multidimensional scaling ordination revealed an increased homogeneity in epigeic fauna where litter was removed.Litterfall,decomposition,diameter increment,four soil physical parameters and fourteen chemical parameters at 0–20 and 20–40 cm depth explained the diff erences in soil epigeic fauna composition between litter removal and control plots.Diameter increment decreased with litter removal only in the juvenile stand,which had reached its growth peak.The results indicate that removing excess litter to decrease fuel volume can alter soil biodiversity and edaphic conditions that negatively aff ect nutrient cycling and tree growth.

STUDIES ON STRUCTURE AND FUNCTIONS OF MONGOLIAN OAK FORESTS

After the investigation and long-lerm research, the structure, succession, energy flow,nutrient and water cycles, produetivity, ete. of Mongolian oak (Quercus mongolica) forest ecosysteins are synthetically summarized. The oak, with a simple stand composition, naturally distributes at hilltops, where the soil is arid and inlfertile and lots of tree species can not grow, and stabilizes for a long period for its high adaptive capacity and long longevity, but it will grow better in good sites.Compared with other forest ecosystems in temperate zone, the oak forest has not only more intensive biological cycles of nutrients but higher productivity as well. Among the nine elements determined, the concentrations of Ca and Zn are the highest and lowest, amounling to 41 .99% and 0.0015%, respectiveiv. In the vegetation, the largest nutrient pool is root svstem, making up 47.75%, and the trunk steps the following, 25. 13%. Among the main secondary forest types in Maoershan region, the oak stands have not only highest biomass but best biomass structure for in which the biomass of trcc stratum reaches 95.6% of the total of the stands and that of trunk does 68.9% of the total of the tree. The oak stands have high steinflow, which amounts to 15.6% of the precipitation and carries a lot of nutrients, and high evapotranspiration, which is as high as 504. 1 mm and for which 77.45% of the total radiation (123.3 KJ. cm-2) is consumed as latent heat transter in the growing reason. The clearcutting of the oak stands will result in not only inereasing the surlace runoff and interflow percentage but also intensitying the loses of N, Ca, Mg and Fe. Finally, it is proposed to pay a great attention to cnltivating.rejuvenating and even planting the oak as high yield timber and water conservation forests.

Heavy Metals in Agricultural Soils of Central Ethiopia: The Contribution of Land Use Types and Organic Sources to Their Variability

In the present study, about 94% of the arable land had a phosphorus deficiency (available P ·kg-1). To compensate for this deficiency, high amounts of phosphorous fertilization were applied to soils to get better crop yield. In the past two decades, soil organic matter has sharply declined from 34.8 g/kg in late 1980s’ to 12.0 g/kg in 2010. The soil has moderate to high cation exchanging capacity (CEC) in the range of 45 - 58 Meq/100 gm. The low soil organic carbon, high CEC and high phosphorus fertilization could lead to poor heavy metal availability to plants. Nevertheless, DTPA extractable concentrations were 40.5 mg/kg for copper, 35.5 mg/kg for iron, 134 mg/kg for manganese, 2.1 mg/kg for nickel, 2.6 mg/kg for lead and 53.5 mg/kg for zinc. All the available micronutrients seem to be adequate for plant growth. In terms of toxicity, the values of Cu, Fe, Mn, Zn, Ni and Pb found in the present investigation were lower than those of above critical value set by the international guidelines and other researchers. Variations in heavy metal content in the soil were attributed due to differences in land use types and disparity in organic sources amongst the plant and animal composites. For better crop productivity, more organic matter should be added to the soils. The traditional nutrient cycling practices, such as manure application, allow crop residue to decay on fields, fallowing and rotational cropping has to be followed to rehabilitate the soil and buildup both macro-and micro-nutrients to their natural level.

Decomposition and stabilization of organic matter in an old-growth tropical riparian forest:effects of soil properties and vegetation structure

Background:Nutrient cycling in tropical forests has a large importance for primary productivity,and decomposition of litterfall is a major process influencing nutrient balance in forest soils.Although large-scale factors strongly influence decomposition patterns,small-scale factors can have major influences,especially in old-growth forests that have high structural complexity and strong plant-soil correlations.Here we evaluated the effects of forest structure and soil properties on decomposition rates and stabilization of soil organic matter using the Tea Bag Index(TBI)in an old-growth riparian forest in southeastern Brazil.These data sets were described separately using Principal Components Analysis(PCA).The main axes for each analysis,together with soil physical properties(clay content and soil moisture),were used to construct structural equations models that evaluated the different parameters of the TBI,decomposition rates and stabilization factor.The best model was selected using Akaike’s criterion.Results:Forest structure and soil physical and chemical properties presented large variation among plots within the studied forest.Clay content was strongly correlated with soil moisture and the first PCA axis of soil chemical properties,and model selection indicated that clay content was a better predictor than this axis.Decomposition rates presented a large variation among tea bags(0.009 and 0.098 g·g^(−1)·d−1)and were positively related with forest structure,as characterized by higher basal area,tree density and larger trees.The stabilization factor varied between 0.211–0.426 and was related to forest stratification and soil clay content.Conclusions:The old-growth forest studied presented high heterogeneity in both forest structure and soil properties at small spatial scales,that influenced decomposition processes and probably contributed to small-scale variation in nutrient cycling.Decomposition rates were only influenced by forest structure,whereas the stabilization factor was influenced by both forest structure and soil properties.Heterogeneity in ecological processes can contribute to the resilience of old-growth forests,highlighting the importance of restoration strategies that consider the spatial variation of ecosystem processes.

Litterfall dynamics and soil carbon and nitrogen stocks in the Brazilian palm swamp ecosystems

Background: This study aimed to determine the litterfall production, accumulation, decomposition rate and nutrient stocks, and to estimate the soil carbon(C) and nitrogen(N) stocks in three palm swamp ecosystems with different land use intensities in the Southeast of Brazil.Methods: Three palm swamp ecosystems with different land use intensities were evaluated: Agua Doce(AD),conserved area;Capivara(CV), area with small agricultural practices;and Buriti Grosso(BG), area with an intensive land use. Produced and accumulated litterfall from the Cerrado areas surrounding the palm swamps were collected from October 2014 to September 2015, and the Ca, Mg, K, and P concentrations were determined in the dry and rainy seasons. Soil samples were collected in the surrounding Cerrado and within the palm swamps until 100 cm soil depth to determine bulk density and soil C and N contents and stocks.Results: Annual litterfall production in the Cerrado surrounding palm swamps was similar in AD(3.58 Mg·ha^-1·year^-1) and CV(3.79 Mg·ha^-1·year^-1), and was lower in BG(2.84 Mg·ha^-1·year^-1), and was more intense during the dry season. Furthermore, litterfall accumulation was higher in CV(7.12 Mg·ha^-1·year^-1) and BG(6.75 Mg·ha^-1·year^-1), culminating in lower decomposition rates. AD showed the highest decomposition rate(0.60) due to its vegetation structure and conservation. The macronutrient contents from the production and accumulated litterfall had a low influence of the land use, decreasing in the following order: Ca > K > Mg > P. Soils in CV and BG palm swamp areas showed higher values of C and N contents, due to the use of land for agricultural crops and cattle raising in an extensive(rangeland) system. The BG palm swamp, showed the highest C(124.03 Mg·ha^-1) and N(10.54 Mg·ha^-1) stocks due to the land use history with different agricultural practices over time.Conclusions: The litterfall dynamics in the Cerrado surrounding palm swamps was more affected by climatic variables than the intensity of land use, but the litter decomposition was more accelerated in the conserved area.Anthropic interventions with soil organic matter(SOM) inputs contributed to an increase in soil C and N stocks in the palm swamp ecosystems.

Phosphorus availability in two soils amended with poultry litter

Understanding P transformation in soils amended with poultry litter is important if water quality is to be protected.Our objectives were to determine the influence of method of litter application and temperature on P availability. Poultry litter containing 20. 8g P/kg (dry weight) was either surface-applied or incorporated into Captina (fine-silty, siliceous, mesic Typic Fragiudult) and Nixa (loamy-skeletal,siliceous,Glossic Fragiudult) silt loams at rates of 0 or 10g/kg and incubated at 20℃ or 35℃ at a water potential of -40 kpa. Water soluble and available P (0.03 mol/L NH4F+0. 025mol/L HCl extraction) were determined during a 60d laboratory study. Results indicated that water soluble and available P levels in the soils initially decreased, then rapidly increased,and approached a steady state phase after approximately 20d. After 60d, water soluble P levels were significantly higher when litter was surface applied than when litter was incor porated. When the incubation was terminated, the net increase in available P in both soils was>100 mg P/kg.For efficient recycling of P and protection of water quality, application method and temperature should be considered when amending soils with poultry litter,

Potential of arbuscular mycorrhizal fungi for soil health:A review

Soil health is an important component of“One Health”.Soils provide habitat to diverse and abundant organisms.Understanding microbial diversity and functions is essential for building healthy soils towards sustainable agriculture.Arbuscular mycorrhizal fungi(AMF)form potentially symbiotic associations with approximately 80%of land plant species that are well recognized for carbon flux and nutrient cycling.In addition to disentangling the signaling pathways and regulatory mechanisms between the two partners,recent advances in hyphosphere research highlight some emerging roles of AMF and associated microbes in the delivery of soil functions.This paper reviews the contribution of AMF to soil health in agroecosystems,with a major focus on recent progress in the contribution of hyphosphere microbiome to nutrient cycling,carbon sequestration,and soil aggregation.The hyphosphere microbiome and fungal stimulants open avenues for developing new fertilizer formulas to promote AMF benefits.In practice,developing AMF-friendly management strategies will have long-term positive effects on sustainable agriculture aiming at simultaneously providing food security,increasing resource use efficiency,and maintaining environment integrity.

Disentangling the contributions of arbuscular mycorrhizal fungi to soil multifunctionality

Soil multifunctionality represents a range of soil processes driven by the interactions between soil abiotic and biotic components.As a group of ubiquitous fungi that form mutualistic symbiotic associations with a vast array of terrestrial plants,arbuscular mycorrhizal(AM)fungi may play a critical role in maintaining soil multifunctionality,but the characteristics of their contributions remain to be unraveled.This mini review aims to disentangle the contributions of AM fungi to soil multifunctionality.We provide a framework of concepts about AM fungi making crucial contributions to maintaining multiple soil functions,including primary productivity,nutrient cycling,water regulation and purification,carbon and climate regulation,habitat for biodiversity,disease and pest control,and pollutant degradation and detoxification,via a variety of pathways,particularly contributing to soil and plant health.This review contends that AM fungi,as a keystone component of soil microbiome,can govern soil multifunctionality,ultimately promoting ecosystem services.