Wheat Litter Research Articles

Wheat cover crop accelerates the decomposition of cucumber root litter by altering the soil microbial community

Cover cropping is a diversifying agricultural practice that can improve soil structure and function by altering the underground litter diversity and soil microbial communities. Here, we tested how a wheat cover crop alters the decomposition of cucumber root litter. A three-year greenhouse litterbag decomposition experiment showed that a wheat cover crop accelerates the decomposition of cucumber root litter. A microcosm litterbag experiment further showed that wheat litter and the soil microbial community could improve cucumber root litter decomposition. Moreover, the wheat cover crop altered the abundances and diversities of soil bacterial and fungal communities, and enriched several putative keystone OTUs, such as Bacillus spp. OTU1837 and Mortierella spp. OTU1236, that were positively related to the mass loss of cucumber root litter. The representative bacterial and fungal strains B186 and M3 were isolated and cultured. In vitro decomposition tests demonstrated that both B186 and M3 had cucumber root litter decomposition activity and a stronger effect was found when they were co-incubated. Overall, a wheat cover crop accelerated cucumber root litter decomposition by altering the soil microbial communities, particularly by stimulating certain putative keystone taxa, which provides a theoretical basis for using cover crops to promote sustainable agricultural development.

Life in the Wheat Litter: Effects of Future Climate on Microbiome and Function During the Early Phase of Decomposition

Even though it is widely acknowledged that litter decomposition can be impacted by climate change, the functional roles of microbes involved in the decomposition and their answer to climate change are less understood. This study used a field experimental facility settled in Central Germany to analyze the effects of ambient vs. future climate that is expected in 50–80 years on mass loss and physicochemical parameters of wheat litter in agricultural cropland at the early phase of litter decomposition process. Additionally, the effects of climate change were assessed on microbial richness, community compositions, interactions, and their functions (production of extracellular enzymes), as well as litter physicochemical factors shaping their colonization. The initial physicochemical properties of wheat litter did not change between both climate conditions; however, future climate significantly accelerated litter mass loss as compared with ambient one. Using MiSeq Illumina sequencing, we found that future climate significantly increased fungal richness and altered fungal communities over time, while bacterial communities were more resistant in wheat residues. Changes on fungal richness and/or community composition corresponded to different physicochemical factors of litter under ambient (Ca2+, and pH) and future (C/N, N, P, K+, Ca2+, pH, and moisture) climate conditions. Moreover, highly correlative interactions between richness of bacteria and fungi were detected under future climate. Furthermore, the co-occurrence networks patterns among dominant microorganisms inhabiting wheat residues were strongly distinct between future and ambient climates. Activities of microbial β-glucosidase and N-acetylglucosaminidase in wheat litter were increased over time. Such increased enzymatic activities were coupled with a significant positive correlation between microbial (both bacteria and fungi) richness and community compositions with these two enzymatic activities only under future climate. Overall, we provide evidence that future climate significantly impacted the early phase of wheat litter decomposition through direct effects on fungal communities and through indirect effects on microbial interactions as well as corresponding enzyme production.

Wheat litter and feed with aluminosilicates for improved growth and meat quality in broiler chickens.

BackgroundNatural minerals have many beneficial properties in poultry production, taking into account production as well as hygiene, health, safety, and quality of broiler meat. The aim of the study was to evaluate the effect of aluminosilicates in feed and litter on the growth performance and meat quality in chickens. Aluminosilicates, including halloysite and zeolite, could be a good alternative for synthetics, as a good solution for the environment in line with the current trends.MethodsFive-hundred male Ross 308 chickens were managed in 5 groups (10 replicates/group): LITTER: 1, control; 2, 0.95 kg/m2 of halloysite; 3, 0.475 kg/m2 of halloysite and 0.475 zeolite; 4, 0.95 kg/m2 of zeolite; 5, 0.25 kg/m2of halloysite and 0.7 kg/m2 of zeolite. FEED: groups 2–5, halloysite and zeolite addition (25:75 ratio; 0.5–2%). Growth performance (body weight and feed indicators), carcass, and meat quality (pH, colour, water-holding capacity, chemical composition of muscles) were recorded. The experimental setup, where the aluminosilicate additives were applied simultaneously, was proposed and approved by experts after pilot testing and on the basis of extensive literature where feed or litter additives were tested.ResultsBody weight and its gain were higher in groups 3 and 4 than in 1, and feed intake was higher in 4. The weight of the carcass and some of its components, including muscles and skin with subcutaneous fat, were higher in 2–4. Water loss from leg muscles was lower in 4. The content of protein in muscles was significantly higher in 3. The addition of aluminosilicates in feed and litter had a positive effect on the growth performance and some traits of carcasses and meat quality, especially in group 3. Halloysite and zeolite can be used in feed and litter (especially 0.475 kg/m2 for each mineral in the wheat litter).

Future Climate Significantly Alters Fungal Plant Pathogen Dynamics during the Early Phase of Wheat Litter Decomposition.

Returning wheat residues to the soil is a common practice in modern agricultural systems and is considered to be a sustainable practice. However, the negative contribution of these residues in the form of “residue-borne pathogens” is recognized. Here, we aimed to investigate the structure and ecological functions of fungal communities colonizing wheat residues during the early phase of decomposition in a conventional farming system. The experiment was conducted under both ambient conditions and a future climate scenario expected in 50–70 years from now. Using MiSeq Illumina sequencing of the fungal internal transcribed spacer 2 (ITS2), we found that plant pathogenic fungi dominated (~87% of the total sequences) within the wheat residue mycobiome. Destructive wheat fungal pathogens such as Fusarium graminearum, Fusarium tricinctum, and Zymoseptoria tritci were detected under ambient and future climates. Moreover, future climate enhanced the appearance of new plant pathogenic fungi in the plant residues. Our results based on the bromodeoxyuridine (BrdU) immunocapture technique demonstrated that almost all detected pathogens are active at the early stage of decomposition under both climate scenarios. In addition, future climate significantly changed both the richness patterns and the community dynamics of the total, plant pathogenic and saprotrophic fungi in wheat residues as compared with the current ambient climate. We conclude that the return of wheat residues can increase the pathogen load, and therefore have negative consequences for wheat production in the future.

Accelerated microbial activity, turnover and efficiency in the drilosphere is depth dependent

Anecic earthworms such as Lumbricus terrestris create effective channels for the translocation of organic substances, nutrients (N, P) and water between top- and subsoil. However, studies on localized and linked microbial activities with the biochemical mechanisms within drilosphere are missing. To clarify the enzymatic mechanisms, zymography was combined with 14C imaging by placing 14C-labeled wheat litter on the surface of mesocosms with top- and subsoil to feed earthworms. Cellobiohydrolase and acid phosphatase activities were compared in drilosphere and bulk soil to test two hypotheses: i) a positive spatial correlation between 14C images and enzyme activities at burrow edges reflects the interactions between substrate distribution and microbial activities; ii) the drilosphere has higher enzyme activities and faster substrate turnover compared to bulk soil independent on depth. In line with the first hypotheses, the localization of substrates (14C) overlapped with enzyme activities for 68%. Spatial distribution of enzyme activities had stronger gradients within 2 mm of burrow edges in topsoil and 4 mm in subsoil. The mineralization of the wheat litter was faster in drilosphere than in the bulk soil. In contrast to our second hypothesis, the substrate turnover was depth dependent: 14CO2 efflux was fourfold faster in topsoil than subsoil drilosphere. The decline of enzyme activities with depth, accompanied by decreasing catalytic efficiency, implies microbial production of more efficient enzymes in top-than in the subsoil.We conclude that interactions between enzymes and substrates are more tight in the drilosphere, making it microbial hotspots. Thus, earthworm activities lead to microbial localization and acceleration of litter decomposition and C turnover in drilosphere. Therefore, both direct hotspot and indirect (soil heterogeneous content) effects need to be explicitly considered when attempting to model and predict how bioturbation evens will alter ecosystem dynamics and ecological development of (micro)habitats.

High carbon use efficiency and low priming effect promote soil C stabilization under reduced tillage

Increasing the accumulation of organic carbon (C) in soils is a crucial challenge both for soil fertility and for climate change mitigation. Heterotrophic microbial communities are key drivers of C cycling in the soil and are influenced by cultural practices, among other factors. However, whether changes in microbial communities in turn affect their C degradation functions is not well understood. Here, we studied the effects of prior soil management on the microbial taxonomic composition and activity of soils amended with wheat litter. Prior soil management was either conventional (CONV) (i.e., full inversion ploughing) or reduced tillage (RT) during a 5-year period in the same loamy soil in northern France. Soil samples taken from the top 5 cm of field plots were incubated with 13C-labelled litter of either flowering wheat or mature wheat for 29 days at 15 °C. We measured the C-CO2 and 13C-CO2, microbial biomass C (MBC) and 13C, and hydrolytic enzyme activities during decomposition. The initial bacterial and fungal community diversity was studied via high-throughput sequencing of ribosomal genes.The results showed that the MBC in the RT soil was initially 1.5-fold greater than that in the CONV soil; contrasting taxonomic compositions were also recorded. The soil biotic legacy impacted the degradation functions when the soils were amended with wheat litter. Compared with that in the CONV soil, the enzymatic efficiency of microorganisms in the RT soil increased by 49% and 61% in the presence of mature and flowering wheat litter, respectively. Enzyme efficiency was positively correlated with microbial litter C use efficiency (CUE) (r = 0.92, P-Value < 0.001) but negatively associated with the priming effect (PE) (r = −0.85, P-value < 0.001) across all soils and litter treatments. These findings demonstrated that the RT soil benefited both from an increase in litter C incorporated in the microbial biomass and from a reduction in soil C loss due to the PE, regardless of the quality of the decomposed litter. Our study indicated that agricultural practices such as RT, which enriches the amount of soil organic C (SOC) in the topsoil layer, can lead to positive feedback against C stabilization functions.

Addition of crop residues affects a detritus-based food chain depending on litter type and farming system

The addition of crop residues is a common farming practice to increase the organic carbon content of agricultural soils with particular importance in organically managed crops. Residues can be added either from the crop plant itself or from other plants and the type of litter may differentially affect decomposer populations. Effects of litter addition may cascade up to affect generalist predators via trophic cascades or modifications of structural microhabitat properties with unknown consequences for the role of these predators in below- and aboveground food webs. Wheat and maize litter were added to organically and conventionally managed wheat fields and effects on generalist predator and Collembola numbers, litter decomposition and carbon utilization as estimated by stable isotope analysis were studied. Significantly more predators were sampled in plots with maize litter compared to plots with wheat litter and under organic farming. Collembola numbers were not significantly affected by litter type or farming system. Litter mass loss was highest in plots that received wheat litter under organic management and was negatively related to predator, but not Collembola numbers. Individuals of Lepidocyrtus spp. (Collembola) incorporated high percentages of maize-borne carbon compared to predator species. Two linyphiid spider species were more closely linked to the maize-consuming prey in organically managed fields and one carabid species showed this pattern in conventionally managed fields. High litter decomposition levels and generalist predator numbers were only observed in wheat litter plots in organically managed fields. The addition of crop residues from the growing crop under organic management may therefore be a promising farming practice to simultaneously promote decomposition services and numbers of natural enemies. Future studies need to address this practice and potential effects on the litter–decomposer–predator food chain across sites that cover a range of different soil types and climatic conditions.

Similar composition but differential stability of mineral retained organic matter across four classes of clay minerals

Adsorption of dissolved organic compounds onto mineral surfaces is increasingly recognized as a significant, if not dominant, carbon stabilisation mechanism in many soils. By utilising carbon-13 enriched dissolved organic carbon (DOC) source materials in a repeated leaching-sorption-incubation study, we show here that the biochemical composition of mineral-retained organic matter (OM) is similar across four different classes of clay minerals but the quantity and stability of this OM is both a function of source material and clay mineralogy. Three to eight times as much carbon was retained on a mass basis when the same amount of DOC derived from eucalyptus versus wheat litter was applied, and the retained wheat-derived OM was up to 2.4 times more degradable than that of the eucalyptus source. For both litter types, carbon retention across the clay types was not significantly different; whereas, the stability of the retained OM was different but depended on which litter extract had been applied. The wheat-derived DOC was more stable when retained by allophane and oxides than by illite and smectite. Solid-state 13C NMR spectroscopic results indicated that despite large compositional differences in both source litter and resultant DOC, the composition of the mineral-retained OM was similar across clay classes with lignin-derived aromatic and carboxylic compounds dominating. Differences in the amount of carbon retained were related to differences in the proportions of aromatic, phenolic and carboxylic C in the DOC produced from the two litter sources. Differences in the stability across the clay classes were correlated with the abundance of metals and short-range ordered minerals. These results suggest that whenever reactive mineral surfaces and metals are present in a soil, a similar form of relatively unaltered litter derived OM can be adsorbed but that the longer term stability of sorbed OM, and thus in situ composition, will be a function of the mineralogy (reactivity) of the specific minerals involved in the binding process.

Does cattle grazing of dual-purpose wheat accelerate the rate of stubble decomposition and nutrients released?

Decomposition and nutrient release of winter annual forages in integrated crop-livestock systems could be affected by the resultant alterations in structure and quality of residues caused by grazing, but little information is available to test this hypothesis. Information on residue dynamics is needed to synchronize nutrient release from cover-crop litter to cash-crop nutrient demand and to overcome potential deficiencies with appropriate fertilization strategies. We evaluated the influence of different grazing period lengths (0, 21, 42, 63, 85, and 105 days) of dual-purpose wheat (Triticum aestivum L.) pasture on the release rate of N, P, K, Ca, and Mg from decomposing wheat straw in a field experiment at the Agronomic Institute of Paraná, Brazil. Wheat litter decomposition and nutrient release were assessed with litter bags placed at the soil surface in a completely randomized design with seven collection periods (0, 15, 35, 63, 98, 139, and 196 days) during the subsequent growth of soybean [Glycine max (L.) Merr.]. Wheat residue decomposition and nutrient release followed an exponential function with time. Enhanced decomposition of wheat residue with previous grazing did occur, but the influence was relatively small (range of 6–11% greater release, except for 4% inhibition of K). In integrated crop-livestock systems, the effect of residual forage mass at the cessation of the grazing season (structure) would have much greater impact on nutrient cycling than composition of plant litter (quality). Nutrient cycling via animal excrement was not investigated, but was considered another significant mechanism for enhanced nutrient cycling with integrated crop-livestock systems. Grazing of wheat tended to have negative consequences on soybean grain yield, declining 9kgha−1 for every day of grazing (i.e. 19% lower yield at 105 days of grazing compared with no grazing). Minor changes in nutrient release dynamics can be expected with grazing of winter cover crops, but these changes are important for managing nutrients in integrated crop-livestock systems.

A new species of the genus Neognathus (Acari: Caligonellidae) from Iran

A new caligonellid mite species of the genus Neognathus , N. rijabicus sp. nov., is described and illustrated from females collected in wheat litter in Kermanshah province, Iran.

Soil respiration and litter decomposition responses to nitrogen fertilization rate in no-till corn systems

Litter decomposition dynamics are influenced by soil nutrient status, yet the specific effects of soil nitrogen (N) on litter decomposition in agricultural systems are not well understood. We explored litter decomposition and related soil organic matter dynamics in no-till, corn-based Midwestern U.S. cropping systems receiving 0, 134, and 291kgNha−1y−1. We found that total soil carbon (C) and N, light fraction organic matter, and permanganate oxidizable C were similar among treatments, but N fertilization at rates of 134 and 291kgNha−1y−1 reduced potentially mineralizable C by as much as 37% and 58%, respectively, compared to the unfertilized treatment. Litter mass remaining after one year of field decomposition was greater with wheat litter (37%) than with corn litter (23%), but was not influenced by N fertilizer rate. In litter, N fertilization led to increases in the activities of two hydrolase enzymes involved in simple carbohydrate metabolism (β-d-cellobiohydrolase and β-1,4-glucosidase) and periodic increases in one related to N metabolism (β-1,4-N-acetylglucosaminidase), but had no effects on enzymes regulating the breakdown of aromatic compounds (phenol oxidase), or on enzymes measured in the soil. N fertilization also decreased arthropod densities in decomposing litter. We found contrasting effects of N fertilizer on processes regulating decomposition, but altogether our results were consistent with a limited or nil role for N fertilization in accelerating litter and soil C turnover, and thus do not support N fertilization as a contributor to depletion of C stocks in agricultural soils.

Arthropod food webs in organic and conventional wheat farming systems of an agricultural long-term experiment: a stable isotope approach

1 Agricultural intensification not only alters the structure of arthropod communities, but also may affect biotic interactions by altering the availability of basal resources. We analyzed variations in stable isotope ratios (15N/14N and 13C/12C) of fertilizers, plants, prey and generalist predators in organic and conventional farming systems in a long-term agricultural experiment [DOK trial (bioDynamic, bioOrganic, Konventionell)]. Two basal resources with pronounced differences in carbon isotope signatures, wheat litter (C3 plant) and maize litter (C4 plant), were used to uncover differences in food web properties between the two farming systems (conventional versus organic). 2 Predators incorporated significantly higher proportions of carbon from wheat sources in organically managed fields, suggesting that they were more closely linked to wheat-consuming prey in this system. The δ15N values of three predaceous species were more than 2‰ greater in summer than in spring. 3 The results obtained suggest that generalist predators consumed higher proportions of herbivore prey in the organic system and that starvation and intraguild predation rates increased in some predator species with time. 4 Because the effects of farming system and sampling date on predators were species-specific, conserving a diverse natural enemy community including species with different phenologies and sensitivities to management practices may, in the long term, be a good strategy for maintaining high pest suppression throughout the growing season.

Soil Textural Control on Decomposition and Soil Organic Matter Dynamics

AbstractSoil texture affects litter decomposition by altering soil water availability, pore size distribution, nutrient availability, and surface area. We examined the direct and indirect effects of soil texture on litter decomposition and soil organic matter mineralization during 91‐d laboratory incubations. Treatments included texture (73, 55, and 40% sand), soil water pressure (−0.012, −0.033, and −0.30 MPa), and nutrient availability (with or without additional N and P). Wheat litter (Triticum aestivum L.) was placed on the surface or incorporated into the soil. Soil texture had no effect on litter decomposition (P &gt;‐ 0.23). Litter decomposition was fastest for the −0.012 MPa treatment across all soil types (P &lt; 0.01), and the difference between water pressure treatments was greatest in the loam (40% sand) soil. The effects of texture and soil water pressure could be combined into one variable (percentage water‐filled pore space), which accounted for more of the variability in litter decomposition and native soil C mineralization than either texture or soil water pressure alone. Surface‐applied litter decomposed significantly faster than incorporated litter, but the effect was not consistent across different soils (P = 0.04). Litter addition stimulated the mineralization of native soil C, the greatest effect occurring when litter was incorporated into the fine‐textured soil.

Solid-state fermentation of new substrates for production of cellulase and other biopolymer-hydrolyzing enzymes

With the realization that the use of leaded gasoline results in environmental pollution and can effect human health, interest in the use of ethanol either directly or as a gasohol is increasing. Production of ethanol from lignocellulosic biomass was commercially practiced during the world wars by acidic hydrolysis technique. However, these processes were found to be uneconomical after the war emergencies were over. An alternate route is the enzymatic hydrolysis of lignocellulosic biomass. However, the economics of the enzymatic hydrolysis process relies substantially on the cost associated with the production of cellulose enzyme. The liquid-state fermentation technique of cellulose enzyme production involves problems related to maintenance of cellulose concentration, inorganic nutrients, and pH. However, the authors feel that the solid-state fermentation (SF) technique may be more suitable for the large-scale production of cellulose enzyme. The cost of substrate and its potential for the induction and production of cellulose, along with other equally important enzymes, such as xylanase, {beta}-1,3-glucanase, chitinase, and cellobiase enzymes, should be studied by selecting different cheap substrates in the SF process. There are several latex- and resin-bearing plants that contain hydrocarbons and related compounds. These plants are called petrocrops, since these hydrocarbons and related compounds can bemore » extracted from these plants by simple heptane extraction. In the present work, the spent residue (SR) obtained after heptane or hexane extraction was used as a substrate for the production of cellulose and related enzymes by the wheat litter decomposing fungi. The results are reported.« less

Observations on the biology ofLonchoptera luteaPanzer (Diptera: Lonch-opteridae) from cereal crops

AbstractIn studies in southern England in 1967–77, the numbers ofLonchoptera luteaPanz. in cereal crops, such as winter wheat, fluctuated from year to year, depending on an adequate supply of food, provided by decaying litter, for the larvae and on sufficient rainfall to keep the soil surface moist during May and June. Much sunshine was unsuitable for larval growth. The larvae fed mainly on fungal spores and were able to breed in wheat litter in the laboratory. In years when many crop plants were attacked by shoot borers such asDelia coarctata(Fall.) andOscinelta frit(L.),L. luteawas more numerous than when there were few. Although in most years more males than females appeared in emergence traps, more females than males were caught by sweeping and in light- and suction traps.