Apple Orchard Soil Research Articles

Continuous N fertilization immobilized nuclear accident-derived 137Cs in apple orchard soil during 10 years after the accident

Continuous N fertilization immobilized nuclear accident-derived ¹³⁷Cs in apple orchard soil during 10 years after the accident

The accumulation of fungal not bacterial residue carbon is management-dependent under conventional and organic practices in apple-orchard soil

Organic orchard management has been widely adopted to enhance soil fertility by improving the sequestration of soil organic carbon (SOC). Microbial residue carbon plays an essential role in SOC accumulation; nevertheless, how fungal and bacterial residue carbon (FRC and BRC) changes with different orchard management practices (organic vs. conventional) and the factors influencing their accumulation remain poorly understood. In this study, we quantified the FRC and BRC in the two management practices, compiled this data with the comparisons of plant, soil and microbial properties, and the dominant factor affecting their sequestration was ascertained with a 4-year orchard experiment on the Jiaodong Peninsula. Compared with conventional management, organic management significantly enhanced SOC and the accumulation of FRC and BRC, while it did not alter the contribution of FRC or BRC to SOC. Furthermore, we identified that the primary determinant affecting FRC varied with management type: Plant (AGR, BGG)-soil (SOC, density)-microbe (Nitrospirae) collectively governed FRC in organic soil, whereas soil (pH, density) and microbial (Ascomycota) properties regulated FRC in conventional soil. Nitrospirae abundance and soil pH played pivotal roles in FRC accumulation under organic and conventional management, respectively. Meanwhile, the primary factor influencing BRC was independent of management type: Soil and microbial properties consistently served as the principal determinants of BRC in both management systems, with soil pH and clay being the pivotal factors in organic and conventional managements, respectively. These findings illustrate the divergent regulatory mechanisms of FRC and BRC in organic and conventional management, thereby enhancing our comprehension of microbial-mediated SOC sequestration in organic orchard management.

Genomic insights into novel Erwinia bacteriophages: unveiling their Henunavirus membership and host infection strategies.

Erwinia amylovora, the primary causative agent of blight disease in rosaceous plants, poses a significant threat to agricultural yield worldwide, with limited effective countermeasures. The emergence of sustainable alternative agents such as bacteriophages is a promising solution for fire blight that specifically targets Erwinia. In this study, we isolated pEp_SNUABM_01 and pEa_SNUABM_55 from a South Korean apple orchard soil, analyzed their genomic DNA sequences, and performed a comprehensive comparative analysis of Hena1 in four distinct sections. This study aimed to unveil distinctive features of these phages, with a focus on host recognition, which will provide valuable insights into the evolution and characteristics of Henunavirus bacteriophages that infect plant pathogenic Erwinia spp. By elucidating the distinct genomic features of these phages, particularly in terms of host recognition, this study lays a foundation for their potential application in mitigating the risks associated with fire blight in Rosaceae plants on a global scale.

Selection of Spectral Parameters and Optimization of Estimation Models for Soil Total Nitrogen Content during Fertilization Period in Apple Orchards

The rapid and accurate diagnosis of nitrogen content in apple orchard soil is of great significance for the rational application of nitrogen fertilizer in orchards to improve apple yield and quality. An apple orchard in Shuangquan Town, Changqing District, Jinan City, Shandong Province, was taken as the experimental area. The optimal method for extracting spectral characteristic bands and screening spectral characteristic indices (SCIs) of soil total nitrogen (TN) for independent and comprehensive fertilization periods was explored. Independent and comprehensive soil TN content estimation models were constructed and optimized for each and the entire fertilization period, respectively. The results show that compared with the correlation coefficient method, stepwise multiple linear regression (SMLR) performs better in extracting hyperspectral characteristic bands of soil TN content. It helps to achieve a higher modeling accuracy, smaller root mean square error (RMSE), and is more conducive to avoiding the influence of multicollinearity of model variables. The sensitive areas of soil TN content in the SCI do not undergo significant changes due to different fertilization periods. Among them, the ratio spectral indices (RSIs) are in the range of 800–900 nm, 1900–1950 nm, and 2200–2300 nm, while the sensitive areas of the difference spectral index (DI) and Normalized difference spectral index (NDSI) are in the range of 1900–1950 nm and 2200–2300 nm. The combination of SCI and characteristic bands significantly improves the prediction accuracy of soil TN estimation models. The independent and comprehensive estimation models for each fertilization period based on the BP (back propagation) neural network optimized by the Mind Evolution Algorithm (MEA-BPNN) can achieve a more stable and accurate estimation of soil TN. Finally, using soil spectral characteristic bands selected through continuum removal (CR) transformation and SMLR, combined with SCI, the model based on the MEA-BPNN (CR-SCI-MEA-BPNN) has the best prediction performance. The modeling determination coefficients R2 for each fertilization period reached 0.94, 0.95, 0.92, and 0.94, respectively, with RMSE of 0.0032, 0.0024, 0.0035, and 0.0027. The R2 and RMSE of the modeling and validation set of the entire fertilization period comprehensive model are 0.899, 0.0038, and 0.89, 0.0041, respectively. The results of this article provide technical support for promoting the timely monitoring of soil TN content and guiding rational fertilization in apple orchards.

Effect of Aged Cherry Orchard Soil on the Potted Seedling Growth of Malus hupehensis (Pamp.) Rehd

Due to the aging of trees, aged apple and cherry orchards need to be rebuilt urgently. However, due to the limitation of land resources, it is inevitable to rebuild the apple orchard by taking the aged cherry orchard as a replacement, which will lead to replant disease and seriously affect the sustainable development of the horticulture industry. This study investigated the effect of aged cherry orchard soil on the growth of M. hupehensis seedlings grown in pots, and it was further verified that allelochemicals in soil were one of the reasons for this effect. Three treatments were implemented: aged apple orchard soil (ppl), aged cherry orchard soil (pyl), and aged cherry orchard soil after fumigation with methyl bromide (pyz). Compared with pyz, pyl treatment significantly decreased the biomass, root growth, and antioxidant enzyme activity of M. hupehensis seedlings, and increased the content of MDA. Compared with ppl, pyl contains a smaller number of fungi and bacteria, but the abundance of the four disease-causing Fusarium remained high. In addition, the levels of allelochemicals found in the soil of aged cherry orchards can inhibit the normal growth and development of M. hupehensis seedlings. Amygdalin most strongly inhibited these seedlings. In summary, directly planting M. hupehensis seedlings in the soil of the aged cherry orchards still inhibits their normal growth and development, although the seedlings grow better than in aged apple orchard soil. Therefore, it is not feasible to directly plant M. hupehensis seedlings in the soil of aged cherry orchards, and measures should be taken to eliminate allelochemicals such as amygdalin and harmful microorganisms.

Effect of Fertilizer, Furrow Length, and Irrigation Flow Rate on Soil Nutrient and Yield of Apple Orchard

The objective of this study was to evaluate the impact of furrow irrigation with a length of 96, 144, and 192 m and a flow rate of between 0.2 and 0.4 Ls−1 on the leaching of nitrogen, phosphorus, and humus from dry subtropical soils in Azerbaijan. Moreover, the impact of six fertilizer levels, namely, control (without fertilizer), 10 t ha−1 of cow manure, N90P90K90 + 10 t ha−1 of cow manure, N120P90K90 + 10 t ha−1 of cow manure, N120P120K90 + 10 t ha−1 of cow manure, and N120P90K120 + 10 t ha−1 of cow manure, on the performance of apple orchards, has been examined. The findings indicate that the brown soils of the irrigated grassland exhibit normal humus, total nitrogen, and weak phosphorus levels, with a gradual decline observed in the lower layers. Applicable to the agricultural and subsurface layers, the aggregates are 0.25–1.0 mm in diameter, with an agricultural value of 12.9% and 21.8%, respectively. This indicates a poor structural condition of the apple orchard soil. The elevation of the water flow rate from 0.2 to 0.4 Ls−1 resulted in a greater extraction of humus, nitrogen, and phosphorus from the soil. Both water flow rates increased the nutrients and humus leaching from the soil. By extending the furrow length to 192 m, the losses of humus (3.25%), nitrogen (0.36%), and phosphorus (0.30%) from the soil in both water flows significantly increased in comparison to the 96‐m length. By extending the length of furrows to 192 m, the yield (21.97 t ha−1) was significantly reduced in comparison to the 96‐m length (22.31 t ha−1). As a consequence of the application of N120P90K120 + 10 t ha−1 of cow manure, the yield of 27.3 t ha−1 was significantly elevated in comparison to other fertilizer treatments and the control treatment (17.9 t ha−1). Therefore, management of fertilizer systems, furrow length, and water flow can improve soil fertility and plant yield by reducing erosion in the meadow‐brown soil of Azerbaijan.

Co-Composting of Hop Bines and Wood-Based Biochar: Effects on Composting and Plant Growth in Copper-Contaminated Soils

Decades of intensive use of copper-based fungicides against downy mildew in hops has led to considerable accumulation of copper in topsoil, resulting in toxic effects on plants. Due to its high sorption capacity, the application of co-composted biochar compost might reduce copper toxicity, whereby a synergistic effect of the composting process is supposed to occur. Furthermore, biochar addition might improve the composting process itself. Therefore, hop bines were co-composted without as well as with 5 and 20 vol% biochar, respectively. During composting, the temperature and concentration of O2, CO2, H2S, CH4 and NH3 in the compost heaps were regularly recorded. The biochar-free compost as well as the two composts with the biochar addition were characterized with regard to their plant-growing properties and were mixed into soils artificially spiked with different amounts of copper as well as into copper-polluted hop garden and apple orchard soils. The respective soil without the compost addition was used as the control, and further treatments with biochar alone and in combination with biochar-free compost were included in a plant response test with Chinese cabbage. The biochar addition increased the temperature within the compost heaps by about 30 °C and extended the duration of the thermophilic phase by almost 30 days, resulting in a higher degree of hygienization. Furthermore, the application of co-composted biochar composts significantly improved plant biomass by up to 148% and reduced the copper concentration, especially of roots, by up to 35%. However, no significant differences in the biochar-free compost were found in the artificially copper-spiked soils, and the effect of co-composted biochar compost did not differ from the effect of biochar alone and in combination with biochar-free compost. Nevertheless, the co-composting of hop bines with biochar is recommended to benefit from the positive side effect of improved sanitization in addition to reducing copper toxicity.

Effects of two apple rootstocks on the soil microecology of replanted apple orchard soil

Apple replant disease (ARD) seriously restricts the development of the apple industry. It is of great significance for the sustainable development of the apple industry to alleviate ARD by using rootstock resistance. Taking M9T337 and Malus robusta Rehd. as test materials, the differences in biomass, soil physical and chemical properties, soil enzyme activity, soil microbial metabolic activity and carbon source utilization characteristics, soil microbial quantity, and soil fungal community of two apple rootstocks in replanted soil. The results showed that the biomass, related soil enzyme activities, and AWCD metabolic activity of apple saplings with Malus robusta Rehd. as rootstock were better, the number of soil fungi and the copy number of four Fusarium genes were lower, and more beneficial bacteria were enriched. In conclusion, the apple saplings with Malus robusta Rehd. as rootstock have a better improvement effect on the replanted soil environment and are more suitable as rootstocks to prevent and control ARD than M9T337.

Nitrogen Mineralization of Apple Orchard Soils in Regions of Western and South-Eastern Norway

The mineralization of nitrogen in apple orchard soil will increase the soil supply. An incubation study to test the soil potential and the validity of analytical methods was conducted at 3, 8, 15, and 20 °C for up to 128 days on soils from western and south-eastern Norway. Soils with the highest pH showed the highest mineralization. The mineralization increased with increasing temperature and time, but start-up N reduced mineralization. The mineralization cannot be estimated from standard soil chemical parameters because the different C/N ratio indicates organic material of different origin and quality. The increase in NO3-N started very quickly and ranged from 17 to 182% and 12 to 64% after 8 days at 3 °C and 20 °C, respectively. There was no correlation between total N in the soil and the amount of mineralized N. On average, the mineralization increased by 5–7% for a change of 1 °C in the interval from 8 to 15 °C in the soil. The chemical extraction method using heated KCl correlated well with the mineralization data. On average, the chemical method estimated 30 kg N ha−1, which corresponded to 0.48% of total N. Recommendations for N fertilization based on total N in the soil overestimate the contribution of plant-available N in most cases.

Effects of different rates of nitrogen fertilizer on apple yield, fruit quality, and dynamics of soil moisture and nitrate in soil of rainfed apple orchards on the Loess Plateau, China

Nitrogen (N) and water deficiency jointly limit apple production in semiarid apple-producing regions worldwide. A 4-year field experiment (2017–2020) was conducted on China’s Loess Plateau to systematically identify the responses of apple yields, fruit quality, and the dynamics of soil water and NO3−-N in 6-m soil profiles to different N (i.e., urea) application rates of 0, 300, 450, 600, 750, and 900 kg N ha−1. The results showed that apple yield averaged 30.02 t ha−1, with remarkable interannual fluctuations, although its differences between N rates were not statistically significant during 2017–2020. Similar responses were recorded for fruit quality indices, except that N-fertilization significantly increased total soluble solids compared with the non-N treatment. Interestingly, soil moisture differed considerably between N rates within the 100–300 cm depth, showing increasing soil moisture with increasing N rates, while an opposite trend was observed at 500–600 cm. The calculated minimum N rates achieving the balanced and maximum soil water storage within the 6-m profile (SWS6 m) were 244 and 323 kg ha1, respectively. Distinctive responses of NO3−-N to N rates were observed at 100–300 cm depth, whereas equivalent NO3−-N concentrations between N rates were recorded across the 520–600 cm depth. The minimum N rates achieving the balanced and maximum residual soil NO3−-N within the 6-m profile (RSN6m) were 412 and 509 kg N ha1, respectively. Notably, SWS significantly linearly increased as a function of RSN across the 6-m soil profile, implying the capacity of N fertilizer to facilitate soil moisture. Collectively, N fertilization slightly affected apple yield and fruit quality but significantly altered soil moisture and NO3−-N within the 6-m soil profile. An N application rate of 412 kg ha1 was recommended to support apple production and maintain balanced SWS6 m and RSN6 m for rainfed apple orchards on China's Loess Plateau.

Apple-marigold intercropping improves soil properties by changing soil metabolomics and bacterial community structures.

Marigold can protect crops against soil-borne diseases. However, the effects of intercropping with marigold on apple rhizosphere soils are not known. In this study, we investigated the metabolite profiles and bacterial community structures in rhizosphere soils of the apple-marigold intercropping system by high-throughput sequencing and soil metabolomics. The results show that intercropping marigold could significantly enhance soil moisture, nitrogen, and enzyme activities compared with clean tillage. The soil metabolite profiles and the soil bacterial community structures in the rhizosphere soils were different between the inter-and mono-cropping systems. Among nine metabolites, carbohydrates were more increased in the intercropping system than in the monocropping system. Pathway enrichment analysis revealed that the greatest differential, in terms of metabolic pathway, was starch and sucrose metabolism. Moreover, intercropping marigold significantly increased the relative abundance of plant growth promoting bacteria in rhizosphere soils, such as Rhizobiales, Pseudomonadales, and Bacillales. These results indicate that marigold intercropping positively affected the apple orchard's soil quality and may provide a new intercropping technique to improve soil fertility in orchards and promote plant growth.

Regulation of microbial community structure, function, and nutrient of apple orchard soil by interplanting red clover

Soil microbial communities are seen to be critical to the maintenance of soil health and quality. Many studies have suggested that soil microbial community composition is affected by different plant species. Based on this theory, we tried to improve the apple orchard soil microorganisms and nutrients by interplanting leguminous forage red clover (RC), meanwhile taking the natural mixed herb (NMH) naturally growing in the orchard as a control. The metagenomic analysis showed that interplanting red clover in the apple orchard markedly improved the soil microbial community composition, especially compared with natural mixed herbs, the abundance ofNitrospiraeandGlomeromycotawas higher. Compared with genus level, there are more unique bacteria species in RC, 84 species were unique to treatment (RC) soil and 43 species were unique to control group (NMH). The activities of glycoside hydrolase and carbohydrate-binding modules in RC were significantly higher than those in NMH, while compared with the control group (NMH), the activity of glycoside hydrolase and carbohydrate binding module in the treatment group (RC) was significantly higher, but the activity of glycosyl transferase was lower. In addition, only 5 of the 15 virulence factors they contain were lower in the RC, while the rest were higher in the control group. Based on the above results, we speculate that intercropping red clover can not only significantly improve soil quality, soil microbial community composition and soil fertility, but also effectively improve land use efficiency and reduce the use of chemical fertilizers.

Apple Root Microbiome as Indicator of Plant Adaptation to Apple Replant Diseased Soils.

The tree fruit industry in Nova Scotia, Canada, is dominated by the apple (Malus domestica) sector. However, the sector is faced with numerous challenges, including apple replant disease (ARD), which is a well-known problem in areas with intensive apple cultivation. A study was performed using 16S rRNA/18S rRNA and 16S rRNA/ITS2 amplicon sequencing to assess soil- and root-associated microbiomes, respectively, from mature apple orchards and soil microbiomes alone from uncultivated soil. The results indicated significant (p < 0.05) differences in soil microbial community structure and composition between uncultivated soil and cultivated apple orchard soil. We identified an increase in the number of potential pathogens in the orchard soil compared to uncultivated soil. At the same time, we detected a significant (p < 0.05) increase in relative abundances of several potential plant-growth-promoting or biocontrol microorganisms and non-fungal eukaryotes capable of promoting the proliferation of bacterial biocontrol agents in orchard soils. Additionally, the apple roots accumulated several potential PGP bacteria from Proteobacteria and Actinobacteria phyla, while the relative abundances of fungal taxa with the potential to contribute to ARD, such as Nectriaceae and plant pathogenic Fusarium spp., were decreased in the apple root microbiome compared to the soil microbiome. The results suggest that the health of a mature apple tree can be ascribed to a complex interaction between potential pathogenic and plant growth-promoting microorganisms in the soil and on apple roots.

Research of Soil Biome of a Young Apple Orchard of Intensive Type

Fungi are one of the main sources of biotic inducers of plant immunity, but among this group of microorganisms, the largest number of phytopathogens is also noted. A two-year study was carried out on the dynamics of the composition and structure of the fungal community in the soil and the agrochemical characteristics of the soil of a young apple orchard of intensive type. The study of the fungi pool in the control (background, without plants) showed that the content of soil saprotrophs and cellulolytics was two times higher than the abundance of these groups in the root zone of a young apple tree. The importance of the role of plant exudates for the formation of the root zone mycobiota, its participation in the differentiation of the soil microbial community and the formation of the “phytogenic region” where root exudates affect the activity and distribution of ecological-trophic groups of fungi, is demonstrated. In the zone of intensive root growth in the 10–20 cm layer, a sharp decrease in the content of macroelements (nitrogen, phosphorus, potassium) was noted.

Combined Application of Organic and Inorganic Fertilizers Effects on the Global Warming Potential and Greenhouse Gas Emission in Apple Orchard in Loess Plateau Region of China

Inorganic fertilizers have been widely used to achieve high apple yields throughout China, especially in Northwest China. This approach has adverse effects on apple orchard soil environments and greenhouse gas (GHG) emissions. Therefore, we investigated the effects of combined organic and inorganic fertilizers on GHG emissions, soil properties, and apple yield to assess the greenhouse gas inventory and to determine which fertilization manner is good for the sustainable development of apple orchards. A split plot design was used, with main treatment of fertilizer ditch (FD) site and a bare soil (BS) site, each with four subtreatments: organic fertilizer–goat manure (M), chemical fertilizer (NPK), chemical fertilizer combined with organic fertilizer–goat manure (MNPK), and control (CK). The cumulative N2O emissions at the FD site were higher than those at the BS site (by 105.72%). The N2O emissions ranged from approximately 0.95–5.91 kg ha−1 and were higher in the MNPK treatment than in the other treatments. The cumulative CH4 uptake from each treatment was generally negative (1.06–7.67 kg ha−1). Compared to the other treatments, the MNPK treatment applied at the FD site led to an increased global warming potential. At both the FD and BS sites, the MNPK treatment led to a lower greenhouse gas intensity than the NPK treatment. Nitrates nitrogen (NO3−-N), water-filled pore space, and temperature all influenced GHG emissions. These results showed that the MNPK treatment was more conducive than the other treatments to the sustainable development of apple orchards in the Loess Plateau region of China.

Effects of soil texture on trace metal concentrations and geochemical fractions in the soil of apple orchards (Çanakkale, NW Turkey)

ABSTRACT The effects of soil texture on trace metal concentrations and geochemical fractions in an apple orchard soils were investigated. For this purpose, soil samples were taken from the apple orchards with two different soil textures located on the same geomorphological unit in Çanakkale, Turkey. A wet digestion was used to determine total trace metal concentrations, and a sequential extraction method was used to determine geochemical fractions of the metals. According to average total concentrations of all metals, except Pb, were found to be significantly higher (p < 0.05) in clay soils. Sequential extraction analysis showed that potential mobile fractions were ordered as Cd (68.8%) > Pb (52.4%) > Cu (42.0%) > Zn (34.8%) > Ni (32.3%) > Cr (22.9%) in clay soils and as Cd (61.6%) > Pb (51.6%) > Cu (40.2%) > Zn (30.7%) > Ni (30.8%) > Cr (24.9%) in loamy soils. The results revealed that all metals, except Pb, in exchangeable/acid soluble, oxidizable and, potential mobile fractions were found to be significantly higher in clay soils (p < 0.05). It was figured out that clay contents played an effective role in total concentrations of metals and their distribution in geochemical fractions.

Effect on microbial communities in apple orchard soil when exposed short-term to climate change abiotic factors and different orchard management practices.

We assessed the effect of exposing apple orchard soil to different temperatures and CO2 levels on the resident microbiome of soils from a conventionally managed and an organically managed apple orchard. The key difference between these two orchards was that synthetic fertilizers and pesticides are routinely used in the former one. To investigate the effect of CO2 and temperature, soil samples from each site at two depths were exposed to either elevated temperature (29°C) at either 5000 or 10 000ppm for five weeks or control conditions (25°C + 400ppm). Both bacterial and fungal communities were profiled with amplicon-sequencing. The differences between the two orchards were the most significant factor affecting the bacterial and fungal communities, contributing to 53.7-14.0% of the variance in Bray-Curtis β diversity, respectively. Elevated CO2 concentration and increased temperature affected organic orchard microbial diversity more than the conventionally managed orchard. A number of candidate beneficial and pathogenic microorganisms had differential abundances when temperature and CO2 were elevated, but their effect on the plant is unclear. This study has highlighted that microbial communities in bulk soils are most significantly influenced by crop management practices compared to the climate conditions used in the study. The studied climate conditions had a more limited effect on microbial community diversity in conventionally managed soil samples than in organically managed soils.

Granulometric composition and moisture capacity of the soil in old-age apple orchards of the Lipetsk region

The research was carried out in 2018-2021 in the old fruit-bearing, but not yet uprooted apple orchards of the Lipetsk region. The lowest moisture capacity was determined by the method of gypsum casts, the granulometric composition was determined by the pyrophosphate method. In old age (40-98 years) in apple orchards on chernozems leached in a layer of 10-40 cm of trunk strips, the granulometric composition changes: the proportion of physical sand increases, but the percentage of physical clay decreases. An increase in the proportion of physical sand in the trunk strips occurs mainly due to an increase in the proportion of fine sand (0.05-0.25 mm), and in the aisles an increase in the amount of physical clay occurs due to an increase in the proportion of medium dust (0.001-0.05 mm). With the age of the garden, the decrease in the proportion of physical clay in the trunk strips occurs due to the removal of medium dust (0.001-0.05 mm) and coarse silt (less than 0.001 mm) down the profile. The lowest moisture capacity increases with an increase in the proportion of coarse silt in the soil (r = 0.5), but decreases with an increase in the percentage of medium (r=-0.65) and coarse (r=-0.53) sand. A decrease in the percentage of physical clay in the trunk strips leads to a decrease in the lowest moisture capacity in a layer of 10-40 cm only by the age of the garden of 98 years. The change of the granulometric composition to a lighter one and the reduction of the lowest moisture capacity of the soil in the trunk strips of old apple orchards are evidence of the podzol–forming activity of apple roots.

Linking microbial carbon pump capacity and efficacy to soil organic carbon storage and stability under heavy metal pollution

Heavy metal pollution can lead to a great loss of soil organic carbon (SOC). However, the microbial mechanisms that link heavy metal pollution to SOC remain poorly understood. Here, we investigated five apple-orchard soils at different distances from a Pb−Zn smelter. After assessing the heavy metal pollution level based on Grade II of the national soil environmental quality standard (China), we found SOC stocks and microbial carbon pump (MCP) capacity (i.e., microbial residue carbon) under medium and heavy pollution levels were significantly lower than those under safe, cordon and light pollution levels. The structural equation model showed causality in the SOC variations linked to pollution level through MCP capacity, which could contribute 77.8% of the variance in SOC storage. This verified MCP capacity can serve as a key parameter for evaluation of SOC storage under heavy metal pollution. Soil MCP efficacy, i.e., the proportion of microbial residue carbon to SOC, also decreased under medium and heavy pollution. This suggested that, with a heavier pollution level, there was a higher rate of reduction of microbial residue carbon in soil than the rate of reduction of SOC. As MCP efficacy can be a useful assessment of SOC stability, the significantly positive relationship between MCP efficacy and clay content in correlation analysis implied that lower MCP efficacy was correlated with SOC stability under the heavier pollution level. Our study provides valuable insights to identify the mechanisms of microbially mediated C transformation processes that are influenced by heavy metal pollution in agroecosystems.

Magnetic Susceptibility Profile, Fe Content and pH Analysis of Apple Orchard Soil and the Relation to Fruit Diameter

The measurement of magnetic susceptibility, pH, element concentration of Fe and apples diameter has been conducted in orchard soil of Malang, East Java Indonesia. The measurement was performed in two orchards, namely Pujon and Poncokusumo with two different kind of apples in each orchard. This research aimed at exploring in detail linked between magnetic properties, the existence of magnetic mineral as magnetic property carrier in the soil, soil pH, as well as the size of apple diameter to evaluate the quality of apple production in the both areas. The results shows that the soil with lower susceptibility, it was expected that the magnetic mineral of magnetic property carrier to be smaller, low soil pH, meaning that the soil was more acidic which implied on a larger size of apple diameter for Rumbeauty type of apple. Meanwhile, when the soil had a higher susceptibility, and it is expected that the magnetic mineral is also high as well as having high pH, this growing media is appropriate to develop Manalagi type of apple. Based on the observed soil magnetic properties and pH from both observed orchards, it can be suggested that Manalagi apple is appropriate to be planted in Poncokusumo area, while Rumbeauty is appropriate to grow in Pujon area.