Litter decay controlled by temperature, not soil properties, affecting future soil carbon.

The growth, development and yield of plant production are influenced by soil properties, both physical, chemical and biological properties of the soil. The physical properties of the soil include texture, structure, consistency, soil moisture (the ability of the soil to hold water) and soil permeability. Soil chemical properties include soil pH, cation exchange capacity and nutrient content. Nutrient content, consisting of mineral and organic content including nitrogen, phosphorus, potassium and other materials. Biological properties of soil are microorganisms that decompose organic matter that live in the soil. To get optimal yields on sandy soil, a solution is needed to solve the problem of physical, chemical and biological properties of sandy soil. This study uses secondary data aimed at knowing the physical, chemical and biological conditions that exist in several coastal areas in Indonesia. The results obtained treatment recommendations to improve the physical, chemical and biological conditions of sandy soil so as to produce optimal plant production. Based on the data obtained, to improve the condition of the sandy soil, several soil amendments can be used, including using compost, manure, biochar, and nitrogen fixing. The results showed that the addition of soil amendments improved soil quality, especially on the physical properties of the soil where in sandy soil the most important thing was the ability of the soil to hold water and maintain available nutrients in the soil. The most important soil chemical properties are the availability of nutrients in the soil. The responses obtained vary, especially in sandy soils and depend on the commodity of the plant. Keywords: biological, physical, chemical, sandy soil, soil

Direct and indirect pathways of land management effects on wetland plant litter decomposition

Effects of temperature increase and nitrogen addition on the early litter decomposition in permafrost peatlands

Litter decomposition plays a pivotal role in the global carbon cycle, but is difficult to measure on a global scale, especially by citizen scientists. Here, citizen scientists, i.e., school students with their teachers, used the globally applied and standardized Tea Bag Index (TBI) method to collect data on litter decomposition in urban areas in Austria. They also sampled soils to investigate the linkages between litter decomposition and soil attributes. For this study, 54 sites were selected from the school experiments and assembled into a TBI dataset comprising litter decomposition rates (k), stabilization factors (S), as well as soil and environmental attributes. An extensive pre-processing procedure was applied to the dataset, including attribute selection and discretization of the decomposition rates and stabilization factors into three categories each. Data mining analyses of the TBI data helped reveal trends in litter decomposition. We generated predictive models (classification trees) that identified the soil attributes governing litter decomposition. Classification trees were developed for both of the litter decomposition parameters: decomposition rate (k) and stabilization factor (S). The main governing factor for both decomposition rate (k) and stabilization factor (S) was the sand content of the soils. The data mining models achieved an accuracy of 54.0 and 66.7% for decomposition rates and stabilization factors, respectively. The data mining results enhance our knowledge about the driving forces of litter decomposition in urban soils, which are underrepresented in soil monitoring schemes. The models are very informative for understanding and describing litter decomposition in urban settings in general. This approach may also further encourage participatory researcher-teacher-student interactions and thus help create an enabling environment for cooperation for further citizen science research in urban school settings.

Decomposition of plant litter, facilitated primarily by microbial decomposers, plays a critical role in biogeochemical cycling and ecosystem function. The rate of litter decomposition can determine its environmental impact, where accelerated decomposition alters the timing and rate of nutrient release and may promote nutrient leaching, whereas slowed decomposition can result in litter accumulation, which impacts seedling recruitment, fire regimes, perennation of microbial communities, and slows nutrient release. Mutualistic endophytes are known to slow litter decomposition, but less is known about the impact that plant pathogens, present in diseased litter, have on decomposition rates. We compared litter decomposition of the invasive annual grass Microstegium vimineum with Bipolaris leaf spot symptoms, a fungal disease, to litter without symptoms of the disease in a year-long common garden experiment. We found leaf tissue with disease symptoms decomposed later in the year compared to litter without symptoms. By summer, 54% of leaf tissue from healthy sites remained compared to 80% of leaf material from diseased litter. Fungal infection did not impact the lignin or C:N content of the litter. There were significant differences in fungal community composition between infected and healthy litter at the start of the experiment that persisted until the end of summer. Disease epidemics prior to senescence contributed to the persistence of infected tissue, which could slow the return of nutrients to the environmental pool and promote the survival and dispersal of pathogen inoculum the following season.

Global patterns and driving factors of plant litter iron, manganese, zinc, and copper concentrations

Linking soil biodiversity and ecosystem function in a Neotropical savanna

This study evaluated the most significant physical, chemical and biological soil properties from a group of organic olive farms located in a typical olive-growing area of Andalusia, Spain, after 5 or more years since the shift from conventional to organic farming, and compared soils with those in nearby undisturbed (U) natural areas. Two soil management systems implemented in these organic olive farms to control weeds, tillage (T), characterized by non-inverting-shallow tillage in spring, and mechanical mowing (M), were compared and evaluated against the U areas. Organic olive orchards showed similar productivity (average fruit yield of 3130 kg ha−1 yr−1) as the conventional, rain-fed olive groves in the same area, with no significant differences due to soil management systems. Soil properties in the olive orchards (i.e. texture, pH, organic carbon (C), organic nitrogen (N), C:N ratio, cation exchange capacity (CEC) and exchangeable potassium) were in the suitable range for olive farming in both soil managements, although organic C and N, saturated hydraulic conductivity and available water-holding capacity (AWC) of the soil were lower than in the U areas. A principal component analysis (PCA) for soil properties in topsoil (0–10 cm depth) distinguished the T from M olive orchards and U areas, and determined organic C and N as the most significant soil properties to characterize them. Average values of soil organic carbon (SOC) stocks for the surface layer (0–10 cm depth) were 18.6, 59.3 and 67.8 Mg ha−1, for T and M soil management systems and U areas, respectively. This indicates that the sustainability of organic olive orchards could be significantly improved by shifting to M soil management to decrease soil erosion and depletion of SOC.

Disturbance can alter tree species and functional diversity in tropical forests, which in turn could affect carbon and nutrient cycling via the decomposition of plant litter. However, the influence of tropical tree diversity on forest floor organisms and the processes they mediate are far from clear. We investigated the influence of different litter mixtures on arthropod communities and decomposition processes in a 60‐year‐old lowland tropical forest in Panama, Central America. We used litter mixtures representing pioneer and old growth tree species in experimental mesocosms to assess the links between litter types, decomposition rates, and litter arthropod communities. Overall, pioneer species litter decomposed most rapidly and old growth species litter decomposed the slowest but there were clear non‐additive effects of litter mixtures containing both functional groups. We observed distinct arthropod communities in different litter mixtures at 6 mo, with greater arthropod diversity and abundance in litter from old growth forest species. By comparing the decay of different litter mixtures in mesocosms and conventional litterbags, we demonstrated that our mesocosms represent an effective approach to link studies of litter decomposition and arthropod communities. Our results indicate that changes in the functional diversity of litter could have wider implications for arthropod communities and ecosystem functioning in tropical forests.

The National Disaster Management Agency (BNPB) identifies eight provinces considered prone to forest and land fires in Indonesia. Four provinces are in Sumatra and four are in Kalimantan, one of which is West Kalimantan. Forest and land fires seem to have become a disaster in West Kalimantan, especially every dry season. Burning activies in the preparation of land for agriculture in the village of Rasau Jaya General is still using a relatively simple technology, namely the method of "slash and burn". The impacts caused by the peat fire process are in the form of water vapor from the combustion process in the air so that smoke formed which is very thick, causes environmental pollution and can affect soil conditions such as physical and chemical properties of peat soils. The purpose of this study was to obtain information about the effects of repeated burning on peatlands on soil characteristics in Rasau Jaya Umum Village, Kubu Raya Regency, West Kalimantan. This research was conducted by survey method and carried out with purposive sampling on 3 research sites, which were on land that had repeated burning twice, 4 times and 5 times. Soil physical properties observed were peat maturity (fiber content), water content, soil moisture, water level and bulk density. The level of fertility of peatlands is influenced by the chemical nature of the soil. The chemical nature of the soil is one of the limiting factors for knowing nutrients in the soil that are beneficial for plant growth. Determination of the level of soil fertility in peatlands can be done by analyzing the chemical properties of the soil. Analysis of the soil chemical properties includes analysis of the main element content such as acidity (pH), nitrogen (N), phosphorus (P), potassium (K) and cation exchange capacity (CEC). The physical properties of the soil consisting of the weight of the contents, the moisture content varies with different levels of burning, the higher the value of the weight of the contents, the more dense a soil and vice versa. In the value of water content, the amount of combustion influences the amount of ground water content, the more number of combustion, the value of water content also increases. Peat environmental conditions observed in the field consisted of soil moisture, soil temperature and ground water level measured for 7 days and obtained a mean value that also varied did not show its effect on the number of repeated fires. The chemical properties of peat soils on the number of repeated burning can increase and decrease each nutrient value consisting of N, P, K and also CEC. Nutrients that increase in the amount of combustion are pH, N, and CEC while the value of nutrients that decrease is K and P. This shows that the greater the level of combustion, the pH, N, and CEC greater.Keywords: peatlands, repeated burning, soil characteristics

Organic matter decomposition in response to thawing permafrost has critical implications for carbon release. This study examined how thaw induced plant community and environmental changes influenced litter and peat decomposition in a subarctic peatland. We conducted laboratory incubations under current site pre-thaw (dry and large oxic peat layer) and thawed (wet and small oxic peat layer) conditions, and mimiced pond thaw conditions (water saturated and anoxic) at 4 and 22 °C. Carbon dioxide (CO2) and methane (CH4) releases from ground surface plant litter and top 1 m peat samples at permafrost area (Palsa) and wet thawed lawn (WL) were quantified under current site conditions. Dissolved organic carbon (DOC) released from litter was additionally quantified under pond thaw conditions. Plant litter mass significantly increased from Palsa to WL. Under current site conditions, litter in WL had significantly higher CO2 and CH4 production rates than litter in Palsa. Pond thaw conditions changed litter carbon loss partitioning into lower CO2 but higher DOC and CH4 production, and increased total carbon release. Whole peat decomposition was restricted from Palsa to WL with thaw. Estimated growing season gas carbon loss (CO2 and CH4) in WL was greater than that in Palsa due to significantly increased litter carbon loss after thaw. Changes in organic matter decomposition, especially litter decomposition, enlarged carbon losses from this subarctic peatland with permafrost thaw.

One of the organic farming goals is improving soil properties to support sustainable rice production. This study investigated the soil properties and rice yields under temporal variation of organic rice fields. Soil sampling was conducted in organic rice fields with three temporal variations, namely 0, 4, 7, and 10 years in a tropical monsoon region in Central Java, Indonesia. Variables observed included soil organic carbon, soil carbon stock, soil microbes population, dissolved organic carbon, soil liquid limit, soil sticky limit, soil plasticity limit, soil color changing limit, soil friability, soil porosity, soil total nitrogen, soil total phosphorus, soil available sulfur, exchangeable calcium, cation exchange capacity, total potassium, bulk density, base saturation, exchangeable sodium, exchangeable potassium, and rice yield. This study confirms that soil organic carbon increased by 51.63% within 10 years (from 1.84% to 2.79%). Organic farming also improved all the physical, chemical, and biological soil properties, by the increase of soil organic carbon. However, soil organic carbon is mostly determined by soil cation exchange capacity, soil total phosphorus, and soil porosity. The mechanism of rice yield increase in organic rice farming is not affected by soil organic carbon directly but through the synergic increase in soil total nitrogen. The 1% increase of soil organic carbon increases 0.065% of soil total nitrogen hence rice yield increases by 1.66 tons ha<sup>-1</sup>. This study supports sustainable agriculture by providing evidence of improved soil properties under organic farming.

Organic carbon release from litter decomposition of woody and herbaceous plants in the Dongting Lake wetlands: A comparative study

Plant litter decomposition is an important biogeochemical process in terrestrial ecosystems. Although climate and substrate quality controls over litter decomposition are reasonably well understood, their impacts on lignocellulose degradation and lignocellulolytic enzymes remain elusive. Here, the decomposition of three leaf litters derived from Salix paraplesia (SP), Deyeuxia scabrescens (DS), and Ajuga ovalifolia (AO), was studied across an alpine forest-tundra ecotone during one snow-covered season with the objective of distinguishing between the effects of microclimate and litter quality on litter decomposition rates and lignocellulolytic enzymes. The results showed that both microclimate and litter quality affected lignocellulose degradation rates and lignocellulolytic enzyme activities; however, microclimate factors had the greater effects. Interestingly, freeze-thaw cycles and moisture were the predominant factors explaining the variations in decomposition rate and enzyme activities. Higher cellulose degradation rates were associated with higher cellulose concentrations. Cellulolytic enzymes had a greater effect on litter decomposition than did ligninolytic enzymes at the early decomposition stage. Litter decomposition and enzyme activities should be given more attention under global climate change, as the direction and magnitude of changes in microclimate factors and litter quality could strongly influence the nutrient cycling and energy fluxes of alpine ecosystems.

Historically, slow decomposition rates have resulted in the accumulation of large amounts of carbon in northern peatlands. Both climate warming and vegetation change can alter rates of decomposition, and hence affect rates of atmospheric CO2 exchange, with consequences for climate change feedbacks. Although warming and vegetation change are happening concurrently, little is known about their relative and interactive effects on decomposition processes. To test the effects of warming and vegetation change on decomposition rates, we placed litter of three dominant species (Calluna vulgaris, Eriophorum vaginatum, Hypnum jutlandicum) into a peatland field experiment that combined warming.with plant functional group removals, and measured mass loss over two years. To identify potential mechanisms behind effects, we also measured nutrient cycling and soil biota. We found that plant functional group removals exerted a stronger control over short-term litter decomposition than did approximately 1 degrees C warming, and that the plant removal effect depended on litter species identity. Specifically, rates of litter decomposition were faster when shrubs were removed from the plant community, and these effects were strongest for graminoid and bryophyte litter. Plant functional group removals also had strong effects on soil biota and nutrient cycling associated with decomposition, whereby shrub removal had cascading effects on soil fungal community composition, increased enchytraeid abundance, and increased rates of N mineralization. Our findings demonstrate that, in addition to litter quality, changes in vegetation composition play a significant role in regulating short-term litter decomposition and belowground communities in peatland, and that these impacts can be greater than moderate warming effects. Our findings, albeit from a relatively short-term study, highlight the need to consider both vegetation change and its impacts below ground alongside climatic effects when predicting future decomposition rates and carbon storage in peatlands.