Litter Controls Earthworm-Mediated Carbon and Nitrogen Transformations in Soil from Temperate Riparian Buffers

Nutrient cycling in riparian buffers is partly influenced by decomposition of crop, grass, and native tree species litter. Nonnative earthworms in riparian soils in southern Quebec are expected to speed the processes of litter decomposition and nitrogen (N) mineralization, increasing carbon (C) and N losses in gaseous forms or via leachate. A 5-month microcosm experiment evaluated the effect of Aporrectodea turgida on the decomposition of 3 litter types (deciduous leaves, reed canarygrass, and soybean stem residue). Earthworms increased CO2 and N2O losses from microcosms with soybean residue, by 112% and 670%, respectively, but reduced CO2 and N2O fluxes from microcosms with reed canarygrass by 120% and 220%, respectively. Litter type controlled the CO2 flux (soybean ≥ deciduous-mix litter = reed canarygrass > no litter) and the N2O flux (soybean ≥ no litter ≥ reed canarygrass > deciduous-mix litter). However, in the presence of earthworms, there was a slight increase in C and N gaseous losses of C and N relative to their losses via leachate, across litter treatments. We conclude that litter type determines the earthworm-mediated decomposition effect, highlighting the importance of vegetation management in controlling C and N losses from riparian buffers to the environment

Phosphorus accumulation in cultivated soils from long-term annual applications of cattle feedlot manure

ABSTRACT increase the risk of P transport to water bodies through leaching, erosion, and runoff processes (Sharpley et al., Historically, manure has been recognized as an excellent soil 1994; Lennox et al., 1997). The transport of soil P to amendment that can improve soil quality and provide nutrients for crop production. In areas of high animal density, however, the potenwater bodies depends on many factors including climate, cattle per year are currently operating (Canada-Alberta Environmentally Sustainable Agriculture Agreement, Experimental Design 1998). Manure from commercial feedlots is generally Beginning in 1973, solid cattle feedlot manure was applied disposed through land application, but most feedlots annually each fall after barley harvest and incorporated immehave a limited land base, and it is often not economical diately after application by one of three methods: plow, rototo broaden the land base by hauling manure long distiller, and cultivator plus disk. Within each tillage treatment tances (Freeze et al., 1999; McKenzie et al., 2000). As has a lower N to P ratio (4:1 to 5:1) than crops (6:1 to 8:1), ments were assigned randomly and replicated three times. and manure applications based on crop N requirements Recommended annual manure applications in Lethbridge, tend to provide P in excess of crop P requirements AB, Canada were 30 Mg manure (wet wt.) ha Ϫ1 for nonirri- (Intensive Livestock Operations Committee, 1995). gated soils and 60 Mg ha Ϫ1 (wet wt.) for irrigated soils at the Over time, this can result in P accumulation in soils and initiation of the experiment (Alberta Agriculture, 1980). Soil properties and crop production were not affected significantl

Changes in the fatty acid profiles through the digestive tract of the earthworm Lumbricus terrestris L.

Abstract The gut of many soil arthropods contains a complex and mutualistic microbial community that usually assists the host with digestion. The same is probably true for earthworms, but the nature and function of the microbiota inhabiting their gut are virtually unknown. In this paper, we studied the microbial community in the gut content of the earthworm Lumbricus terrestris L. and in the bulk soil by assessing their fatty acid (FA) profiles. Our results indicated that the total FA concentration in the earthworm gut was about two orders of magnitude greater than in bulk soil, with higher concentration of bacteria (up to 500-fold), fungal and metazoanderived FAs. Several FAs appearing in the gut were not present in bulk soil. PCA analysis revealed that the microbial community in the gut was different from that in the bulk soil, and that significant changes occurred between midgut, hindgut and proctodeum. Cluster analysis of bacterial and fungal-derived FA profiles grouped the bulk soil samples apart from the gut samples, where the hindgut profiles were more closely related to those from the proctodeum than those from the midgut. We showed important changes in the FA concentration and composition occurring at very small spatial scales inside the gut of the earthworm L. terrestris. These results have implications for understanding earthworm digestion, and they suggest that the microbial community in the earthworm gut is not a casual combination of microorganisms already present in the soil. Further study is needed to determine how these gut microbial communities are involved in earthworm digestion processes.

Nitrous oxide and carbon dioxide emissions from surface and subsurface drip irrigated tomato fields

Irrigation practices change the soil moisture in agricultural fields and influence emissions of greenhouse gases (GHG). A 2 yr field study was conducted to assess carbon dioxide (CO2) and nitrous oxide (N2O) emissions from surface and subsurface drip irrigated tomato (Solanum lycopersicum L.) fields on a loamy sand in southern Ontario. Surface and subsurface drip irrigation are common irrigation practices used by tomato growers in southern Ontario. The N2O fluxes were generally ≤50 μg N2O-N m⁻² h⁻¹, with mean cumulative emissions ranging between 352 ± 83 and 486 ± 138 mg N2O-N m⁻². No significant difference in N2O emissions between the two drip irrigation practices was found in either study year. Mean CO2 fluxes ranged from 22 to 160 mg CO2-C m² h⁻¹ with cumulative fluxes between 188 ± 42 and 306 ± 31 g CO2-C m⁻². Seasonal CO2 emissions from surface drip irrigation were significantly greater than subsurface drip irrigation in both years, likely attributed to sampling time temperature differences. We conclude that these irrigation methods did not have a direct effect on the GHG emissions from tomato fields in this study. Therefore, both irrigation methods are expected to have similar environmental impacts and are recommended to growers

Movement of N from decomposing earthworm tissue to soil microbial and plant N pools

Abstract A microcosm experiment was made to determine the fate of nitrogen released from 15 N-labelled decomposing earthworms (Lumbricus terrestris) in soil in the presence or absence of ryegrass seedlings (Lolium perenne). Earthworm tissue (2.0% 15 N atom enriched) was added to each microcosm. Nitrogen movement from earthworm tissue to soil N [mineral N (NH 4 -N + NO 3 -N), dissolved organic N (DON) and organic N], microbial biomass N and plant shoot N pools was determined by destructive sampling at 1, 2, 4, 8 and 16 d. Earthworm tissues decomposed rapidly, and no tissue was visible after 4 d. Initially in pots without plants, most of the N from earthworm tissue was found in the organic N pool, however, as much as 55% of the N from decomposing earthworm tissue was incorporated into microbial biomass after 2 d. Much less of the N from earthworm tissue was transformed into DON and mineral N forms after 2 d. The DON and mineral N pools contained 13±18% and 4±7% of the N from earthworm tissue, respectively, from d 2 to 16. By the end of the experiment, N from earthworm tissue in the microbial biomass N pool declined to 29% while the amount of N from earthworm tissue in the organic N pool increased to 49%. The increase in the organic N may have resulted from the production of new organic compounds such as microbial by-products. In pots with plants, N from earthworm tissue was rapidly incorporated into microbial biomass, and by d 2, the microbial biomass N pool contained 40% of the N from earthworm tissue. Mineral N, DON and microbial biomass N concentrations were lower in pots with ryegrass seedlings compared to pots without plants, and after d 2 declined to almost undetectable amounts because of rapid plant uptake. Between 42±52% of the N from earthworm tissue was found in the organic N pool from d 1 to 8, and then declined to 19% by d 16. After 16 d, over 70% of the N added as earthworm tissue was incorporated into plant shoot biomass. Our results demonstrate that the movement of N from dead earthworm tissue into microbial biomass was extremely rapid, and in pots without plants, much of this N was transformed into organic N forms, while in pots with ryegrass, most of the N from earthworm tissue accumulated in ryegrass shoots.

Expansion of Agriculture in Northern Cold-Climate Regions: A Cross-Sectoral Perspective on Opportunities and Challenges

Agriculture in the boreal and Arctic regions is perceived as marginal, low intensity and inadequate to satisfy the needs of local communities, but another perspective is that northern agriculture has untapped potential to increase the local supply of food and even contribute to the global food system. Policies across northern jurisdictions target the expansion and intensification of agriculture, contextualized for the diverse social settings and market foci in the north. However, the rapid pace of climate change means that traditional methods of adapting cropping systems and developing infrastructure and regulations for this region cannot keep up with climate change impacts. Moreover, the anticipated conversion of northern cold-climate natural lands to agriculture risks a loss of up to 76% of the carbon stored in vegetation and soils, leading to further environmental impacts. The sustainable development of northern agriculture requires local solutions supported by locally relevant policies. There is an obvious need for the rapid development of a transdisciplinary, cross-jurisdictional, long-term knowledge development, and dissemination program to best serve food needs and an agricultural economy in the boreal and Arctic regions while minimizing the risks to global climate, northern ecosystems and communities

Global data on earthworm abundance, biomass, diversity and corresponding environmental properties

Publisher Copyright: © 2021, The Author(s).Earthworms are an important soil taxon as ecosystem engineers, providing a variety of crucial ecosystem functions and services. Little is known about their diversity and distribution at large spatial scales, despite the availability of considerable amounts of local-scale data. Earthworm diversity data, obtained from the primary literature or provided directly by authors, were collated with information on site locations, including coordinates, habitat cover, and soil properties. Datasets were required, at a minimum, to include abundance or biomass of earthworms at a site. Where possible, site-level species lists were included, as well as the abundance and biomass of individual species and ecological groups. This global dataset contains 10,840 sites, with 184 species, from 60 countries and all continents except Antarctica. The data were obtained from 182 published articles, published between 1973 and 2017, and 17 unpublished datasets. Amalgamating data into a single global database will assist researchers in investigating and answering a wide variety of pressing questions, for example, jointly assessing aboveground and belowground biodiversity distributions and drivers of biodiversity change.Peer reviewe

Global data on earthworm abundance, biomass, diversity and corresponding environmental properties

Earthworms are an important soil taxon as ecosystem engineers, providing a variety of crucial ecosystem functions and services. Little is known about their diversity and distribution at large spatial scales, despite the availability of considerable amounts of local-scale data. Earthworm diversity data, obtained from the primary literature or provided directly by authors, were collated with information on site locations, including coordinates, habitat cover, and soil properties. Datasets were required, at a minimum, to include abundance or biomass of earthworms at a site. Where possible, site-level species lists were included, as well as the abundance and biomass of individual species and ecological groups. This global dataset contains 10,840 sites, with 184 species, from 60 countries and all continents except Antarctica. The data were obtained from 182 published articles, published between 1973 and 2017, and 17 unpublished datasets. Amalgamating data into a single global database will assist researchers in investigating and answering a wide variety of pressing questions, for example, jointly assessing aboveground and belowground biodiversity distributions and drivers of biodiversity change

Managing Soil Biota-Mediated Decomposition and Nutrient Mineralization in Sustainable Agroecosystems

Transformation of organic residues into plant-available nutrients occurs through decomposition and mineralization and is mediated by saprophytic microorganisms and fauna. Of particular interest is the recycling of the essential plant elements—N, P, and S—contained in organic residues. If organic residues can supply sufficient nutrients during crop growth, a reduction in fertilizer use is possible. The challenge is synchronizing nutrient release from organic residues with crop nutrient demands throughout the growing season. This paper presents a conceptual model describing the pattern of nutrient release from organic residues in relation to crop nutrient uptake. Next, it explores experimental approaches to measure the physical, chemical, and biological barriers to decomposition and nutrient mineralization. Methods are proposed to determine the rates of decomposition and nutrient release from organic residues. Practically, this information can be used by agricultural producers to determine if plant-available nutrient supply is sufficient to meet crop demands at key growth stages or whether additional fertilizer is needed. Finally, agronomic practices that control the rate of soil biota-mediated decomposition and mineralization, as well as those that facilitate uptake of plant-available nutrients, are identified. Increasing reliance on soil biological activity could benefit crop nutrition and health in sustainable agroecosystems