Loss Of Soil Organic Matter Research Articles

The Effect of Different Fire Regimes on Soil Properties in Wet Miombo woodlands of Zambia

Miombo woodlands occur on nutrient poor soils and generally experience a warm-to-hot climate with a dry cold season. Wet miombo areas, which receives more than 1,000 mm of average annual rainfall, are distinguished from dry miombo areas receiving less than 1,000 mm of average annual rainfall. Wet miombo woodland occurs over much of eastern Angola, northern Zambia, south western Tanzania and central Malawi in areas receiving more than 1000 mm rainfall per year. Canopy height is usually greater than 15 m, reflecting the generally deeper and moister soils which create favourable conditions for growth. The objective of this study was to investigate the effect of different fire regimes on soil properties in wet Miombo woodlands of Zambia. The study was conducted in Mwekera burning plots located in Mwekera National Forest No. 6 on the outskirts of Kitwe City. This study has uncovered some interesting relationships between fire and soil nutrients, soil chemical and physical properties. The complete fire protected treatment had significantly greater soil bulky density, organic soil carbon, phosphorus (P) and nitrogen (N) than other treatments. The late burning treatment had significantly greater soil pH, soil electrical conductivity, Calcium (Ca) and magnesium (Mg) than other treatments; however, a loss of soil organic matter during late burning fires likely resulted in increased bulk density and strength, and decreased water infiltration rates. Late burning fires also significantly increased soil pH, concentrations of extractable calcium, magnesium and carbon although to a lesser degree than early burning. Early burning fires did not lower soil potassium contents or alter soil chemical and physical properties. Our results indicate that despite differences in fire regimes, soil moisture, calcium and magnesium contents were not significantly different between early burning and late burning treatments. The results suggest that fire management did not affect soil moisture, calcium, and magnesium contents. Keywords: burning plots, fire regimes, soil properties, wet miombo woodlands DOI: 10.7176/JRDM/66-04 Publication date: June 30th 2020

Use of solid anaerobic digestate and no-tillage practice for restoring the fertility status of two Mediterranean orchard soils with contrasting properties

Soil structure degradation, declining soil organic matter and nutrient losses are among major drawbacks of continuous conventional tillage with large-scale environmental consequences including decreasing soil productivity, groundwater contamination and greenhouse gases emissions. This becomes especially true in conventionally-tilled Mediterranean croplands which are also affected by severe climatic conditions. In this study, a one-year field experiment was carried out to investigate the impact of different tillage practices on the soil fertility status in two tree orchards (olive, citrus) soils with contrasting texture (clay, sandy loam), carbonate content (non-calcareous, slightly calcareous) and pH (strongly acid, slightly alkaline), located in Southern Italy. Treatments included in this study were conventional tillage, conventional tillage combined with the incorporation of solid anaerobic digestate, and no-tillage. Changes in the aggregate stability and dynamics of various C and N pools were assessed by monitoring a large set of physical (aggregate stability index), chemical (pH, electrical conductivity, total organic C, total N, nitrate-N, ammonium-N, total soluble N, extractable organic N), biochemical (microbial biomass C and N, basal respiration, potentially mineralizable N) and eco-physiological (microbial and metabolic quotients, mineralization coefficient) soil variables. Results showed that the stability of soil aggregates declined under conventional tillage, remained unaltered under no-tillage, improved after digestate amendment. Moreover, following incorporation of digestate large and long-lasting increase of the organic pool, microbial C-use efficiency and release of soluble C and N forms were observed in the fine-textured soil. Whereas opposite responses were found in the moderately coarse alkaline soil, where incorporation of digestate stimulated C resources depletion, microbial respiration and N losses due to ammonia volatilization with less beneficial effects on soil organic pools. On the other hand, no-tillage prevented soil C and N resources from over-exploitation (as observed in conventionally-tilled soils) with greater beneficial effects on microbial C-use efficiency and biomass found in the coarse than in the fine-textured soil. Our findings suggest that improved management practices such as no-tillage or conventional tillage combined with incorporation of solid anaerobic digestate should specifically deal with soil and climate conditions to became effective for restoring the fertility status in Mediterranean orchard soils.

The wind erodibility in the newly emerged surfaces of Urmia Playa Lake and adjacent agricultural lands and its determining factors

Despite the great extent of Urmia Playa Lake (UPL), researchers have rarely ever studied the development of playa surfaces and their vulnerability to dust emission. Therefore, we aimed the current research to study the formation of UPL surfaces and how their physicochemical, mineralogical and geomorphological characteristics affect their susceptibility to wind erosion. An area of 41 km2 was chosen including lands from UPL and adjacent Agricultural Lands (AL). Different playa surfaces were identified on different geomorphic surfaces and mapped using Landsat images. Later, 75 soil samples from depth of 0–5 cm of different map units were collected and subjected to physicochemical analysis. Soil Erodible Fraction (EF) was also measured as an index for the wind erodibility of the examined soil surfaces. X-Ray Diffraction (XRD) and X-Ray Fluorescence (XRF) analysis of soil samples from three playa surfaces with significantly different EF values were also conducted. Major reasons for the development of different playa surfaces were found to be basically related to geomorphic surfaces on which they have developed, size and mineralogical composition of the sediments as well as the landscape position and depth to the groundwater. Statistical analysis of EF of different playa surfaces and AL showed that Salt Crusts (SC) had the lowest mean EF value due to the formation of a thin layer of salt on its surface as it has developed on low stand geomorphic surface being fine-textured by nature and rich in Na, Mg and Cl ions. Abandoned Agricultural lands (AA) and AL had the highest mean EF values. High sand content of soils with anthropogenic origin along with conventional tillage practices resulting in soil organic matter loss and over grazing were the major reasons of their high EF. Therefore, these surfaces need to be monitored carefully and to be of high priority of conservation and dust control programs in the region.

Soils

Soil is defined as a mixture of weathering products of rocks (sand, silt, and clay) and humus (or soil organic matter) derived from plant or animal. World soils are divided into 12 groups and their distribution is not uniform. Soil degradation includes soil acidification in humid region, salinization in arid regions, and loss of soil organic matter in both regions. Minimum tillage or optimized fallow systems can minimize loss of soil organic matter and improve soil fertility. Understanding of complex soil system is required for food supply and human survival.

DRIFTS band areas as measured pool size proxy to reduce parameter uncertainty in soil organic matter models

Abstract. Soil organic matter (SOM) turnover models predict changes in SOM due to management and environmental factors. Their initialization remains challenging as partitioning of SOM into different hypothetical pools is intrinsically linked to model assumptions. Diffuse reflectance mid-infrared Fourier transform spectroscopy (DRIFTS) provides information on SOM quality and could yield a measurable pool-partitioning proxy for SOM. This study tested DRIFTS-derived SOM pool partitioning using the Daisy model. The DRIFTS stability index (DSI) of bulk soil samples was defined as the ratio of the area below the aliphatic absorption band (2930 cm−1) to the area below the aromatic–carboxylate absorption band (1620 cm−1). For pool partitioning, the DSI (2930 cm−1 ∕ 1620 cm−1) was set equal to the ratio of fast-cycling ∕ slow-cycling SOM. Performance was tested by simulating long-term bare fallow plots from the Bad Lauchstädt extreme farmyard manure experiment in Germany (Chernozem, 25 years), the Ultuna continuous soil organic matter field experiment in Sweden (Cambisol, 50 years), and 7 year duration bare fallow plots from the Kraichgau and Swabian Jura regions in southwest Germany (Luvisols). All experiments were at sites that were agricultural fields for centuries before fallow establishment, so classical theory would suggest that a steady state can be assumed for initializing SOM pools. Hence, steady-state and DSI initializations were compared, using two published parameter sets that differed in turnover rates and humification efficiency. Initialization using the DSI significantly reduced Daisy model error for total soil organic carbon and microbial carbon in cases where assuming a steady state had poor model performance. This was irrespective of the parameter set, but faster turnover performed better for all sites except for Bad Lauchstädt. These results suggest that soils, although under long-term agricultural use, were not necessarily at a steady state. In a next step, Bayesian-calibration-inferred best-fitting turnover rates for Daisy using the DSI were evaluated for each individual site or for all sites combined. Two approaches significantly reduced parameter uncertainty and equifinality in Bayesian calibrations: (1) adding physicochemical meaning with the DSI (for humification efficiency and slow SOM turnover) and (2) combining all sites (for all parameters). Individual-site-derived turnover rates were strongly site specific. The Bayesian calibration combining all sites suggested a potential for rapid SOM loss with 95 % credibility intervals for the slow SOM pools' half-life being 278 to 1095 years (highest probability density at 426 years). The credibility intervals of this study were consistent with several recently published Bayesian calibrations of similar two-pool SOM models, i.e., with turnover rates being faster than earlier model calibrations suggested; hence they likely underestimated potential SOM losses.

Glomalin - an interesting protein part of the soil organic matter

The negative effects of the current agricultural practices include erosion, acidification, loss of soil organic matter (dehumification), loss of soil structure, soil contamination by risky elements, reduction of biological diversity and land use for non-agricultural purposes. All these effects are a huge risk to the further development of soil quality from an agronomic point of view and its resilience to projected climate change. Organic matter has a crucial role in it. Relatively significant correlations with the quality or the health of soil parameters and the soil organic matter or some fraction of the soil organic matter have been found. In particular, Ctot, Cox, humic and fulvic acids, the C/N ratio, and glomalin. Our work was focused on glomalin, a glycoprotein produced by the hyphae and spores of arbuscular mycorrhizal fungi (AMF), which we classify as Glomeromycota. Arbuscular mycorrhiza, and its molecular pathways, is not a well understood phenomenon. It appears that many proteins are involved in the arbuscular mycorrhiza from which glomalin is probably one of the most significant. This protein is also responsible for the unique chemical and physical properties of soils and has an ecological and economical relevance in this sense and it is a real product of the mycorrhiza. Glomalin is very resistant to destruction (recalcitrant) and difficult to dissolve in water. Its extraction requires specific conditions: high temperature (121°C) and a citrate buffer with a neutral or alkaline pH. Due to these properties, glomalin (or its fractions) are very stable compounds that protect the soil aggregate surface. In this review, the actual literature has been researched and the importance of glomalin is discussed.

Short-Term Effects of Recent Fire on the Production and Translocation of Pyrogenic Carbon in Great Smoky Mountains National Park

Fire affects the quantity and quality of soil organic matter (SOM). While combustion of the O-horizon causes direct losses of SOM, fire also transforms the remaining SOM into a spectrum of thermally altered organic matter. Pyrogenic carbon (PyC) can resist degradation and may have important effects on soil carbon cycling. The objectives of this study are to examine the mobility of PyC. Studying the effects of wildfire is challenging due to the rapid post-fire changes in the ecosystem and lack of robust controls. We overcame those limitations by examining the Chimney Tops 2 Fire which burned 4,617 ha of the Great Smoky Mountains National Park (GRSMNP), including a National Ecological Observatory Network (NEON) site, in November 2016. We examined PyC in soils from three time points from an area burned at low-severity (pre-, immediate post-, and 11 months post-fire) and two time points from areas burned at lower to higher severity (immediate post- and 11 months post-fire). At locations with pre-fire soil samples we found that PyC increased in the O-horizon (2.22 g BPCA/kg soil) after low severity fire, which resulted in higher PyC concentrations at 5-10 cm (0.73 g BPCA/kg soil and 17.79 g BPCA/kg C) and 10-20 cm (12.19 g BPCA/kg C) of depth in the mineral soil. Sites burned at higher severity had more PyC in the O horizon relative to sites burned at lower severity (10.29 g BPCA/kg soil and 29.89 g BPCA/kg C). As a result of higher concentrations of PyC in the O-horizons burned at higher severity, statistically more PyC moved from the O-horizon to the 0-10 cm horizon from immediate to 1-year post-fire (1.37 g BPCA/kg soil and 16.10 g BPCA/kg C). Lastly, the depth profile of C and BPCA suggest a shift in the source and amount of PyC in these soil profiles over time – possibly as a result of fire suppression. Results indicate that low severity fire may be an important mechanism by which PyC is produced and transported into mineral soils.

Short-term casting activity of earthworm Pontoscolex corethrurus (Oligochaeta: Glossoscolecidae) after biochar additions

Conversion of forests to cultivated farms through slash-and-burn or chop-and-char practices often results in rapid loss of soil organic matter (SOM) or conversion of inherent SOM into pyrogenic organic matter (PyOM). However, there is little knowledge about the short-term changes in soil macrofauna that may occur when large amount of biochar are added to the soil. A thirty-day microcosm study was conducted to assess effects of biochar derived from two trees, Croton megalocarpus Hutch. and Zanthoxylum gilletii (De Wild.) P.G.Waterman, on the activity of a geophagous earthworm, Pontoscolex corethrurus. A portion of the biochar was leached with either acetone or 2 M HCl, to remove easily mineralizable organic matter and ash contents, respectively. Each of the biochar types was mixed with soil at a rate equivalent to 5, 10 and 25 Mg ha−1. Casts were collected after 30 days and used as a measure of earthworms’ activity. Casts dry weight was affected more by amount than the type of biochar. The highest cast weight (188.1 g and 176.5 g) was recorded in microcosm that received 5 Mg ha−1 of C. megalocarpus and Z. gilletii biochar, respectively. Notably, the weight decreased with increasing biochar additions. Cast weight decreased by 4% in microcosms that received 10 Mg of C. megalocarpus biochar ha−1 and by 15% in microcosms that received the same biochar type at a rate of 25 Mg ha−1. Similarly, there was a 6% decline in cast weight in microcosms that received 10 Mg of Z. gilletii biochar ha−1 and an 8% decline in microcosms amended with 25 Mg ha−1 of the same biochar type. Easily mineralizable organic matter or nutrients were not responsible for the observed differences in cast production since leaching with acetone or HCl did not change the effects. The C and N content in casts and bulk soil were not significantly different, an indication that earthworms did not seek out biochar, but rather indiscriminately utilised the soil rich in biochar.

Assessing the Impacts of Tillage and Mulch on Soil Erosion and Corn Yield

Conventional tillage practices have been regarded as the major reason for the loss of fertile topsoil in the sloping agricultural lands of the middle hills of Nepal. Reports on the effects of no-till and mulch on soil and corn yield in these regions are scarce, although these farming practices have been recommended to reduce soil erosion and increase crop yields. To assess the impacts of tillage (with +T, without −T) and mulch (with +M, without −M) on soil and soil nutrient losses, and corn yield, we conducted an experiment with five treatments: −T+M, −T−M, +T+M, +T−M, and bare fallow (BF), replicated four times each in an unbalanced complete random block design in Salyan district of Nepal. The results showed the presence of corn and no-till significantly lowered the soil losses. Losses of soil organic matter (SOM) and total nitrogen were also significantly reduced by the presence of corn, no-till, and mulch. However, no effects of mulch on soil losses, and no effects of tillage, mulch and corn on soil phosphorus losses were observed. Soil loss was found to be significantly and positively correlated with total seasonal rainfall, monsoon being the most severe season for soil erosion. While no-till and mulch did not affect corn height, cob height, and stover yield, no-till significantly increased the corn yield by 0.52 Mg ha−1 compared to conventional till. We confirm the synergistic interaction of mulch with tillage to reduce the losses of SOM and total nitrogen, and effectiveness of no-till to reduce the soil losses and increase the corn yield in the middle hills of Nepal. As this study is based on the results of two year’s data, long-term studies are required to identify the long-term impacts of no-till and mulch on soil losses and corn yield across the country.

Stakeholder Perspectives to Prevent Soil Organic Matter Decline in Northeastern Italy

A transition from conventional to more sustainable soil management measures (SMMs) is required to reverse the current soil organic matter (SOM) losses in the agroecosystems. Despite the innovations and technologies that are available to prevent SOM decline, top–down knowledge transfer schemes that incentivize a certain measure are often ineffective. Here, we discuss relevant outcomes from a participatory approach where researchers, farmers, practitioners and government officials have discussed opportunities and barriers around SMM application to prevent SOM decline. Within a series of workshops, stakeholders identified, scored, and selected SMMs to field-tests and evaluated the benefits and drawbacks from their application. Results showed that the stakeholders recognized the need for innovations, although they valued the most promising SMM as already available continuous soil cover and conservation agriculture. In contrast, more innovative SMMs, such as biochar use and the variable rate application of organic amendments through precision farming, were the least valued, suggesting that people’s resistance to new technologies is often governed by the socio-cultural perception of them that goes beyond the economic and technological aspects. The valuation of benefits and drawbacks by stakeholders on trialed measures emphasized that stakeholders’ perspective about soil management is a combination of economic, environmental, and socio-cultural aspects, thus corroborating the need for transdisciplinary bottom–up approaches to prevent SOM depletion and increase soil rehabilitation and SOM content.

Modern Approaches to Environmental and Economic Estimation of Damage From Soil Erosion

Actuality. Despite a nearly century-old history of erosion damage assessments, this issue has not yet been finally resolved. If the economic component of losses can be relatively easily calculated, then environmental and socio-environmental damage are almost impossible to calculate. Purpose. To show the possibilities and limitations of using individual indicators for assessment of damage and the environmental and economic justification of anti-erosion measures based on analysis of the environmental, economic and social consequences of soil erosion, and world experience in assessing damage from erosion. Results. Losses from erosion today are most often estimated by the mass of washed soil (t / ha), the cost of restoring lost nutrients and organic matter, as well as the cost of agricultural products lost due to reduced yields on eroded soils and stop cultivation of hard eroded soils. Soil losses are usually estimated by mathematical modeling. Different approaches to the assessment of losses give a ten-fold difference in the estimates, which reduces the credibility of them when making decisions. Land users are not interested in investing in anti-erosion measures more than the cost of the crop, which they can additionally receive. In Ukraine, this leads to a de facto neglect of the problem of erosion, which, developing on the principle of positive feedback, leads to the deepening of socio-economic problems and the deterioration of the country's food security Conclusions. To justify anti-erosion measures at the level of land users, the only reliable source for quantifying the potential damage from erosion is the shortage of agricultural products and the loss of soil organic matter and fertilizers. The real damage from erosion lies in the plane of global environmental processes and food security, therefore, the problem of erosion should be addressed at the national level.

Changes in soil organic carbon and nitrogen after 47 years with different tillage, stubble and fertiliser management in a Vertisol of north-eastern Australia

No-till (NT) farming has been widely adopted to assist in reducing erosion, lowering fuel costs, conserving soil moisture and improving soil physical, chemical and biological characteristics. Improvements in soil characteristics are often driven by the greater soil organic matter accumulation (as measured by soil organic carbon (SOC)) in NT compared to conventional tillage (CT) farming systems. However, to fully understand the effect of NT it is important to understand temporal changes in SOC by monitoring over an extended period. We investigated the long-term effect of NT and stubble retention (SR) on changes in SOC and total soil nitrogen (STN) using results from an experiment that has been running for 50 years in a semi-arid subtropical region of north-eastern Australia. In this experiment, the effects of tillage (CT vs NT), residue management (stubble burning (SB) vs SR), and nitrogen (N) fertiliser (0 and 90 kg-N ha–1) were measured in a balanced factorial experiment on a Vertisol (Ustic Pellusert). The use of NT, SR and N fertiliser generally improved SOC (by up to 12.8%) and STN stocks (by up to 31.7%) in the 0–0.1 m layer relative to CT, SB and no N fertiliser, with the greatest stocks observed where all three treatments were used in combination. However, declines in SOC (up to 20%) and STN (up to 25%) occurred in all treatments over the course of the experiment, indicating that changes in management practices were unable to prevent a loss of soil organic matter over time in this farming system. However, the NT and SR treatments did lose less SOC than CT and SB treatments, and SR also reduced STN loss. The δ13C analysis of samples collected in 2008 and 2015 highlighted that crop residues have significantly contributed to SOC stocks at the site and that their contribution is increasing over time.

Soil carbon dynamics following the transition of permanent pasture to cereal cropping: influence of initial soil fertility, lime application and nutrient addition

Soil organic matter (SOM) in agricultural soils is generally lower in cultivated and intensively managed cropping soils than in pasture soils. Cultivation during the transition from pasture to crop leads to a loss of SOM, which may affect soil functionality and subsequent agricultural productivity. However, it is unclear how management practices influence SOM dynamics following this transition. We investigated the impact of initial soil fertility and application of lime and nutrients (nitrogen (N), phosphorus (P) and sulfur (S)) on changes in soil carbon (C) during the transition from a permanent pasture to a crop. The pasture was managed over 20 years with fertiliser to generate soils with initial high and low fertility (referred to as P2 and P0, respectively), based on soil C, N, P and S concentrations. Prior to sowing, pasture residue was incorporated with three treatments applied: control, lime, and lime + nutrient. Two successive crops of triticale (Triticale (× Triticosecale)) were then grown. The P0 and P2 soils were again cultivated in March 2018 with incorporation of the triticale stubble residue (9 Mg ha–1) in each of the three soil treatments. After the two successive cereal crops, higher whole-soil C stocks were retained in the P2 than the P0 soils (difference of 2.1 Mg C ha–1 compared with an initial difference in stocks of 2.4 Mg C ha–1), with smaller loss of whole-soil C in P2 soils receiving the lime and lime + nutrient treatments than in the P2 control (average 10.3%, 10.0% and 20.2% loss of total C, respectively, relative to initial levels of soil C). Loss of C from the more active >0.4-mm fraction as a proportion of total C loss was higher in the first year with incorporation of legume-based pasture residue than in the second year with incorporation of C-rich, nutrient-poor crop residue (56% and 18% of the loss of C from the whole soil was from the >0.4-mm fraction in the first and second year, respectively). In P2 soil, loss of C was smaller in the more stable <0.4-mm fraction in the lime and lime + nutrient treatments than in the control (average loss of 9.6%, 11.2% and 17.6%, respectively). By contrast, in the low-fertility (P0) soil, loss of C was greater in the <0.4-mm fraction in the lime treatment than in the control (12.3% and 3.4% loss, respectively) unless supplementary nutrients were added at the time of cultivation (7.0% loss). Narrowing of nutrient ratios (C:N and C:S) in the P0 whole soil over time suggested that the loss of soil C was associated with increased microbial processing of C in the coarse-fraction soil. Taken together, the results demonstrate that loss of C from the pasture soils after cultivation was lower for soil with initially higher soil fertility when lime was applied, and that for soils with lower initial fertility, application of nutrients in addition to those for crop growth reduced C mineralisation induced by lime application.

Short-Term Effects of Tillage Intensity and Fertilization on Sunflower Yield, Achene Quality, and Soil Physicochemical Properties under Semi-Arid Conditions

Inappropriate soil management practices and specific climatic conditions in semi-arid region cause loss of soil organic matter (SOM), decline soil fertility, and trigger soil erosion processes and desertification. A two-year field study was carried out to investigate the effects of tillage intensity and fertilizer regime treatments on the productivity of sunflower (Helianthus annus L.) and soil physicochemical properties in the semi-arid highland region in northwest Iran (37°31′ north (N), 46°53′ east (E)). Five fertilizer treatments were included under conventional (CT) or reduced tillage systems (RT): F1, no fertilizer application; F2, 20 t∙ha−1 farmyard manure (FYM); F3, 40 t∙ha−1 FYM; F4: 20 t∙ha−1 FYM + 50% of the recommended dose of nitrogen–phosphorus–potassium (NPK) chemical fertilizer; F5: full dose of the recommended chemical NPK fertilizer. Results showed that utilization of FYM decreased bulk density (BD); its effects were more evident under the highest SOM content for the F2 and F3 treatments, whereas application of mineral fertilizer had no significant effect upon SOM content, and elevated levels of FYM preserved higher organic carbon contents in topsoil. The highest N, P, and K contents of the soil were obtained with FYM plus inorganic fertilizer application in the RT system. Hydraulic conductivity and soil moisture content were significantly improved by RT and FYM application. The highest root growth was observed for F3 and F4 under the RT system. The effect of fertilizer and tillage treatments was more pronounced during the second year. Traits related to growth and seed quality such as achene oil content, leaf area, and harvest index were enhanced by chemical fertilization in the CT system. The highest achene yield and oil percentage were recorded for plants grown with F3 and F4. The best option for enhancing sunflower productivity and quality in semi-arid, high-altitude environments is the application of organic fertilizers amended with reduced amounts of chemical fertilizers.

Biochar application and no-tillage practices to minimize the residues of herbicides in the seeding hole

BackgroundNo-tillage is considered as a promising alternative for conventional farming by saving energy input and time, reducing groundwater pollution, and counteracting soil erosion and losses of soil-organic matter. Therefore, this study was carried out in north-eastern Sylhet of Bangladesh during the period of 2015–2016 to evaluate the multiple techniques of implementation in order to find a practically appropriate way to apply biochar.ResultsIn this study, successfully applied of biochar and glyphosate in holes with seeds and consisted of one control (pure soil), glyphosate control, biochar control, and four glyphosate treatments with 1, 2.5, 5, and 10% biochar addition. The Gly + ch1% and Gly + ch2.5% treatments demonstrated a better emergence rate than all treatments, and at the end of the emergence, they reached more than 95%. There was no important distinction found among all the treatments in the event of shooting fresh and dry biomass. Biochar amendment treatments did not show any influence on shoot fresh biomass compared to glyphosate control and biochar 5% treatment, respectively. Gly + ch2.5% treatment showed slightly better performance than all the other treatments. The similar performance was shown in case of shoot dry weight. In case of root fresh weight, there was only a significant different observed between Gly + ch1% and Gly + ch10%. However, Gly + ch1% treatment revealed slightly higher root fresh weight compared to all the other treatments. Considering the results of the germination percentage and root morphology, it could be suggested that lower rate of biochar application showed better performance on root length and development.ConclusionsIt could be concluded that glyphosate application has mitigation effect to absorb herbicidal residues. For successful introduction of biochar application in agriculture, field acts as a huge amount of carbon sink and has also a positive effect to mitigate climate change.

Effects of land use change on turnover and storage of soil organic matter in a tropical forest

Land-use change of tropical forests causes loss of soil organic matter and plant productivity. Effects of fallow or plantation vegetation on soil organic matter storage need to be clarified to optimize land-use that maximizes soil organic matter storage and plant productivity. We compared 30-year changes in soil carbon stocks and litter decomposition under different land-uses (primary dipterocarp forest, Macaranga forest, Imperata grassland, transition of Imperata grassland to Acacia plantation, transition of Imperata grassland to oil palm plantation) in Indonesia. The Imperata grassland maximizes soil carbon stocks for up to 10 years due to considerable root litter inputs, but additional organic matter storage is limited over the following 20 years, due to high grass litter decomposability in the less acidified soil. The conversion of Imperata grassland to oil palm plantation causes greatest loss of soil organic matter, whereas Acacia plantation on Imperata grassland or the Macaranga forest maximizes soil carbon stocks due to input of recalcitrant forest litters and reduced microbial activities in the acidified soils. Farmers could adopt short-term ( 10 years) fallow under Acacia plantation on Imperata grassland or Macaranga regeneration forest to maximize soil organic matter storage. The optimum and feasible land-use strategies should be selected based on the length of fallow period and the original acidity of soil.

Mycorrhizal Fungi as Mediators of Soil Organic Matter Dynamics

Inhabiting the interface between plant roots and soil, mycorrhizal fungi play a unique but underappreciated role in soil organic matter (SOM) dynamics. Their hyphae provide an efficient mechanism for distributing plant carbon throughout the soil, facilitating its deposition into soil pores and onto mineral surfaces, where it can be protected from microbial attack. Mycorrhizal exudates and dead tissues contribute to the microbial necromass pool now known to play a dominant role in SOM formation and stabilization. While mycorrhizal fungi lack the genetic capacity to act as saprotrophs, they use several strategies to access nutrients locked in SOM and thereby promote its decay, including direct enzymatic breakdown, oxidation via Fenton chemistry, and stimulation of heterotrophic microorganisms through carbon provision to the rhizosphere. An additional mechanism, competition with free-living saprotrophs, potentially suppresses SOM decomposition, leading to its accumulation. How these various nutrient acquisition strategies differentially influence SOM formation, stabilization, and loss is an area of critical research need.

Effects of Soil Aggregate Stability on Soil Organic Carbon and Nitrogen under Land Use Change in an Erodible Region in Southwest China.

Soil aggregate stability can indicate soil quality, and affects soil organic carbon (SOC) and soil organic nitrogen (SON) sequestration. However, for erodible soils, the effects of soil aggregate stability on SOC and SON under land use change are not well known. In this study, soil aggregate distribution, SOC and SON content, soil aggregate stability, and soil erodibility were determined in the soils at different depths along the stages following agricultural abandonment, including cropland, abandoned cropland, and native vegetation land in an erodible region of Southwest China. Soil aggregation, soil aggregate stability, and SOC and SON content in the 0–20 cm depth soils increased after agricultural abandonment, but soil texture and soil erodibility were not affected by land use change. Soil erodibility remained in a low level when SOC contents were over 20 g·kg−1, and it significantly increased with the loss of soil organic matter (SOM). The SOC and SON contents increased with soil aggregate stability. This study suggests that rapidly recovered soil aggregate stability after agricultural abandonment promotes SOM sequestration, whereas sufficient SOM can effectively maintain soil quality in karst ecological restoration.

Implementation of environmental management policies on the impact of illegal sand mining

Environmental issues have not become a serious concern of the South Buton District Government as evidenced by sand mining managed by the people illegally mushrooming almost all of South Buton Regency and there has been no control, prevention or prosecution from the Office related to the issue. Although this mining affair has become the authority of the provincial government, based on Law Number 23 the Year 2014 concerning Regional Government but the adverse impact of the consequences of sand mining in the local area that feels environmental damage. The related office is just giving an appeal about the ban on sand mining. But that is how there is no other way for people’s livelihoods to live. Mining activities include a series of activities in the effort to search, mine, excavate, process, utilize, and sell minerals. The existence of mining C in South Buton District is considered as a manifestation of the community’s efforts to maintain its life through efforts to increase revenue. Miners and people living around it are two components that influence each other. This is the background of the author to examine how government policies in overcoming the impact of mining C (sand) excavation in South Buton Regency. This study aims to determine how the policy of the South Buton District Government in overcoming the impact of excavated sand mining C in South Buton Regency. This type of research is empirical juridical research. Research location in South Buton Regency. Respondents in this study were the Office of the Environment of South Buton Regency and the head of the family affected around the sand mine. Primary and secondary data are collected through interviews with respondents using observation and documentation, which will then be analyzed qualitatively. The results of this study are known that the Local Government through the Department of Environment is only limited to providing warnings on negative environmental impacts that occur, among others, the occurrence of deep basins due to mining of lands prone to landslides, the potential for flooding in the lower regions, loss of soil organic matter, loss of soil layers, changes in soil structure, air pollution in the form of dust, and damage to village roads. The positive socio-economic impacts that occur include increased income, increased welfare, and reduced unemployment.

Effect of paddy straw burning on soil microbial dynamics in sandy loam soil of Indo-Gangetic plains

Abstract The rice–wheat cropping system generates large quantities of crop residues and its disposal is of major concern, particularly in the Indo-Gangetic plains. A large quantity of the paddy straw is burnt on the farm to clear the field for succeeding crop, especially in the irrigated and mechanized rice–wheat system of north-west India. Besides causing air pollution, burning of paddy straw leads to the loss of soil organic matter and essential nutrients, reduces microbial activities and the land more vulnerable to soil erosion. This study was undertaken to investigate the soil microbial dynamics in response to paddy straw burning at a farmer’s field in Panipat (Haryana, India). Samples were collected (0–10 cm depth ) on 0, 7, 15, 30 and 60 days from the paddy straw burnt (T1), manual harvesting or residue removed (T2) and the whole residue retained (T3) treatments. Paddy straw burning resulted in a significant reduction in the population of major groups of microorganisms-bacteria, fungi, actinomycetes, phosphate solubilizing microorganism (PSM), potassium solubilizing microorganism (KSM) and cellulose degraders immediately after burning. However, sampling after 30–60 days of burning revealed that the abundance of these groups was normalized. Similarly, the microbial enzymes and other soil health parameters showed a transient decrease after burning. Interestingly, the microbial population and enzyme activities involved in biomass recycling could not recover, even after 60 days, perhaps, due to unavailability of substrates. From a long term standpoint, this may lead to deleterious effects on soil health.