An official website of the United States government
The purpose of this study was to assess the effects of charcoal and earthworm presence in contrasting soil types of northern Japan using the biologically based phosphorus (BBP) extraction method, which employs a variety of plant P acquisition strategies. Using soils developed in serpentine and sedimentary parent materials, we tested the interactive effects of Eisenia japonica (Michaelsen) earthworms and 500 kg ha−1 of dwarf bamboo charcoal (Sasa kurilensis (Rupr.) Makino et Shibata) in a microcosm incubation that lasted four weeks. Soils were extracted in parallel after the incubation with the BBP method using 0.01 M CaCl2 (soluble P), 0.01 M citric acid (chelate-extractable P), 0.02 phosphatase enzyme units ml−1 (enzyme-extractable organic P), and 1.0 M HCl (mineral occluded P). Dwarf bamboo charcoal alone contained up to 444 mg total BBP kg−1 prior to application to soil microcosms. Treatment effects in soil microcosms were highest in sedimentary soil types and where charcoal was combined with earthworms (15.97 mg P kg−1 ± SE 1.23 total inorganic BBP). Recalcitrant inorganic P (HCl extracted) in combination treatments yielded the highest single inorganic BBP measure (12.41 mg kg−1 ± SE 1.11). Our findings suggest that charcoal, as a legacy of wildfire, and native earthworm activity may help stimulate cycling of recalcitrant inorganic BBP pools.
more »
« less
Biologically Available Phosphorus in Biocrust-Dominated Soils of the Chihuahuan Desert
In desert soils, phosphorus (P) cycling is controlled by both geochemical and biological factors and remains less studied than nitrogen and carbon. We examined these P cycling factors in the context of biological soil crusts (biocrusts), which are important drivers of nutrient cycling in drylands and have the potential to release bound labile P. We adopted the biologically-based P (BBP) method, which allows examination of biologically relevant P fractions. The BBP method incorporates four extractions: dilute calcium chloride (CaCl2), citric acid, phosphatase enzymes, and hydrochloric acid (HCl). We coupled the extractions with a 33P-labeled orthophosphate addition and incubation to assess the fate of freshly available phosphate (PO43−). Low P concentrations in the dilute CaCl2 extractions suggest that drylands lack accessible P in the soil solution, while higher amounts in the citric acid- and enzyme-extractable pools suggest that dryland microbes may acquire P through the release of organic acids and phosphatases. The addition of 33PO43− was, within 24 h, quickly adsorbed onto mineral surfaces or incorporated into hydrolysable organic compounds. Areas with biocrusts showed overall lower P concentrations across all four extractable pools. This suggests that biocrust organisms may prevent P adsorption onto mineral surfaces by incorporating P into their biomass. Overall, our results indicate that organisms may have to employ several viable strategies, including organic acid and enzyme production, to access P in dryland soils.
more »
« less
- PAR ID:
- 10476440
- Publisher / Repository:
- MDPI
- Date Published:
- Journal Name:
- Soil Systems
- Volume:
- 2
- Issue:
- 4
- ISSN:
- 2571-8789
- Page Range / eLocation ID:
- 56
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract Phosphorus (P) limits or co‐limits plant and microbial life in multiple ecosystems, including the arctic tundra. Although current global carbon (C) models focus on the coupling between soil nitrogen (N) and C, ecosystem P response to climate warming may also influence the global C cycle. Permafrost soils may see enhanced or reduced P availability under climate warming through multiple mechanisms including changing litter inputs through plant community change, changing plant–microbial dynamics, altered rates of mineralization of soil organic P through increased microbial activity, and newly exposed mineral‐bound P via deeper thaw. We investigated the effect of long‐term warming on plant leaf, multiple soil and microbial C, N, and P pools, and microbial extracellular enzyme activities, in Alaskan tundra plots underlain by permafrost. Here, we show that 25 yr of experimental summer warming increases community‐level plant leaf P through changing community composition to favour relatively P‐rich plant species. However, despite associated increases in P‐rich litter inputs, we found only a few responses in the belowground pools of P available for plant and microbial uptake, including a weak positive response for citric acid–extractable PO4in the surface soil, a decrease in microbial biomass P, and no change in soil P (or C or N) stocks. This weak, neutral, or negative belowground P response to warming despite enhanced litter P inputs is consistent with a growing number of studies in the arctic tundra that find no long‐term response of soil C and N stocks to warming.more » « less
-
Drylands encompass over 40% of terrestrial ecosystems and face significant anthropogenic degradation causing a loss of ecosystem integrity, services, and deterioration of social‐ecological systems. To combat this degradation, some dryland restoration efforts have focused on the use of biological soil crusts (biocrusts): complex communities of cyanobacteria, algae, lichens, bryophytes, and other organisms living in association with the top millimeters of soil. Biocrusts are common in many ecosystems and especially drylands. They perform a suite of ecosystem functions: stabilizing soil surfaces to prevent erosion, contributing carbon through photosynthesis, fixing nitrogen, and mediating the hydrological cycle in drylands. Biocrusts have emerged as a potential tool in restoration; developing methods to implement effective biocrust restoration has the potential to return many ecosystem functions and services. Although culture‐based approaches have allowed researchers to learn about the biology, physiology, and cultivation of biocrusts, transferring this knowledge to field implementation has been more challenging. A large amount of research has amassed to improve our understanding of biocrust restoration, leaving us at an opportune time to learn from one another and to join approaches for maximum efficacy. The articles in this special issue improve the state of our current knowledge in biocrust restoration, highlighting efforts to effectively restore biocrusts through a variety of different ecosystems, across scales and utilizing a variety of lab and field methods. This collective work provides a useful resource for the scientific community as well as land managers.more » « less
-
Abstract The capture and use of water are critically important in drylands, which collectively constitute Earth's largest biome. Drylands will likely experience lower and more unreliable rainfall as climatic conditions change over the next century. Dryland soils support a rich community of microphytic organisms (biocrusts), which are critically important because they regulate the delivery and retention of water. Yet despite their hydrological significance, a global synthesis of their effects on hydrology is lacking. We synthesized 2,997 observations from 109 publications to explore how biocrusts affected five hydrological processes (times to ponding and runoff, early [sorptivity] and final [infiltration] stages of water flow into soil, and the rate or volume of runoff) and two hydrological outcomes (moisture storage, sediment production). We found that increasing biocrust cover reduced the time for water to pond on the surface (−40%) and commence runoff (−33%), and reduced infiltration (−34%) and sediment production (−68%). Greater biocrust cover had no significant effect on sorptivity or runoff rate/amount, but increased moisture storage (+14%). Infiltration declined most (−56%) at fine scales, and moisture storage was greatest (+36%) at large scales. Effects of biocrust type (cyanobacteria, lichen, moss, mixed), soil texture (sand, loam, clay), and climatic zone (arid, semiarid, dry subhumid) were nuanced. Our synthesis provides novel insights into the magnitude, processes, and contexts of biocrust effects in drylands. This information is critical to improve our capacity to manage dwindling dryland water supplies as Earth becomes hotter and drier.more » « less
-
{"Abstract":["Interactions between plants and soil microbes influence plant\n nutrient transformations, including nitrogen (N) fixation, nutrient\n mineralization, and resource exchanges through fungal networks.\n Physical disturbances to soils can disrupt soil microbes and\n associated processes that support plant and microbial productivity.\n In low resource drylands, biological soil crusts\n ("biocrusts") occupy surface soils and house key\n autotrophic and diazotrophic bacteria, non-vascular plants, or\n lichens. Interactions among biocrusts, plants, and fungal networks\n between them are hypothesized to drive carbon and nutrient dynamics;\n however, comparisons across ecosystems are needed to generalize how\n soil disturbances alter microbial communities and their\n contributions to N pools and transformations. To evaluate linkages\n among plants, fungi, and biocrusts, we disturbed all unvegetated\n surfaces with human foot trampling twice yearly in dry conditions\n from 2013-2018 in cyanobacteria-dominated biocrusts in Chihuahuan\n Desert grassland and shrubland ecosystems. Our study included\n microbial communities and N pools sampled at different time points\n in the disturbance treatments at one or both sites. We began our\n sampling after observations in April 2018 that the chlorophyll a\n content was at least double in control than disturbed plots in both\n ecosystems (Chung et al. 2019). Stomping occurred in May, and we\n collected soil and plant samples in June 2018 for N pools and soil\n and root fungal abundance. We collected additional soil samples in\n September 2018 and conducted the 15N tracer experiment to observe\n rates of N transfer from biocrust to plants before the fall stomp\n treatment in October. We collected chlorophyll a samples and soils\n for sequencing bacteria in September of 2019, also before the fall\n stomp treatment."]}more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3390/soilsystems2040056
