Increased Soil Nutrient Research Articles

Combined System of Organic Substrate and Straw-Degrading Microbial Agents Improved Soil Organic Matter Levels and Microbial Abundance in a Rice-Wheat Rotation.

Rice-wheat rotation is one of the most intensive agricultural planting modes in China and is pivotal to develop optimized straw-returning management in situ to improve soil fertility and productivity in agricultural ecosystems. Previous studies have mainly focused on the effects of straw return with a single application of organic fertilizers. The integrated management of different fertilizers in improving the management of straw return in situ is not well known. In this study, a field experiment was conducted from 2017 to 2019 to explore the effects of a combined system of modified organic substrate (MOS) and straw-degrading compound microbial agent (CMA) on soil physiochemical properties, labile organic carbon, microbial activities, and soil microbial community composition under the background of direct crop straw return and chemical fertilizer utilization. Four treatments were designed: (1) control check; (2) CMA; (3) MOS; and (4) MOS + CMA. The results showed that theMOS + CMA treatment had the combined advantages of soil organic matter (SOM) accumulation, soil nutrient increase and soil microbial community alteration, which may be more suitable for improving the quality and fertility of sandy loam soil. This study provides novel insights for further understanding the effects of organic substrates and composite microbial agents on SOM changes and microbial community composition and function in the field, which has important implications for sustainable crop production and agricultural development.

Biofilm biofertilizer application rapidly increases soil quality and grain yield in large scale conventional rice cultivation: a case study

Excessive use of chemical fertilizers (CF) has led to degrade agroecosystems, and human and environmental health. In this context, maintaining soil quality has been challenging. As alternatives to CF, ecofriendly substitutes are being tested, but to a lesser extent. Amongst, Biofilm biofertilizers (BFBF) which improve soil and crop yields are being popularized among farmers. Thus far, there is no published research regarding the effect of BFBF on soil quality and crop production at large scale cultivations. Therefore, present study investigated this in lowland rice farming of Sri Lanka. The study was carried out in 54 farmer fields spreading over thousands of hectares in three districts representing major rice growing areas. In each location, two consecutive, uniform paddy fields were applied separately with farmers’ CF practice and the newly introduced BFBF practice. Root zone soil samples were collected and analyzed for 16 physico-chemical and microbial parameters, and grain yield was recorded at harvest. The results showed that the application of BFBF increased soil nutrient contents and microbial communities, and finally it led to increase grain yield over the CF alone practice. A significant relationship between a developed soil quality index (SQI) and grain yield only in the BFBF practice indicated that the soil has a major role to play only in ecofriendly rice cultivation. It is concluded from this study that the CF alone application would not be sufficient to break yield barrier for which the reinstated microbial action of BFBF is a must.

Wood vinegar facilitated growth and Cd/Zn phytoextraction of Sedum alfredii Hance by improving rhizosphere chemical properties and regulating bacterial community

Soil Cd and Zn contamination has become a serious environmental problem. This work explored the performance of wood vinegar (WV) in enhancing the phytoextraction of Cd/Zn by hyperaccumulator Sedum alfredii Hance. Rhizosphere chemical properties, enzyme activities and bacterial community were analyzed to determine the mechanisms of metal accumulation in this process. Results demonstrated that, after 120 days growth, different times dilution of WV increased the shoot biomass of S. alfredii by 85.2%–148%. In addition, WV application significantly increased soil available Cd and Zn by lowing soil pH, which facilitated plant uptake. The optimal Cd and Zn phytoextraction occurred from the 100 times diluted WV (D100), which increased the Cd and Zn extraction by 188% and 164%, compared to CK. The 100 and 50 times diluted WV significantly increased soil total and available carbon, nitrogen and phosphorus, and enhancing enzyme activities of urease, acid phosphatase, invertase and protease by 10.1–21.4%, 29.1–42.7%,12.2–38.3% and 26.8–85.7%, respectively, compared to CK. High-throughput sequencing revealed that the D 100 significantly increased the bacterial diversity compared to CK. Soil bacterial compositions at phylum, family and genera level were changed by WV addition. Compared to CK, WV application increased the relative abundances of genus with plant growth promotion and metal mobilization function such as, Bacillus, Gemmatimonas, Streptomyces, Sphingomonas and Polycyclovorans, which was positively correlated to biomass, Cd/Zn concentrations and extractions by S. alfredii. Structural equation modeling analysis showed that, soil chemical properties, enzyme activities and bacterial abundance directly or indirectly contributed to the biomass promotion, Cd, and Zn extraction by S. alfredii. To sum up, WV improved phytoextraction efficiency by enhancing plant growth, Cd and Zn extraction and increasing soil nutrients, enzyme activities, and modifying bacterial community.

Effects of soil conditioning, root and shoot litter addition interact to determine the intensity of plant–soil feedback

Plant–soil feedback (PSF) is recognized as an important mechanism shaping plant communities and determining plant abundance and coexistence. Under natural conditions, plants affect the outcome of plant–soil interactions simultaneously by conditioning the soil by living roots and by litter inputs into the soil. However, most experimental studies only focus on one of the pathways, which limits our understanding of PSF in the field.Here, we simultaneously explored the effect of soil conditioning by living roots and of root and shoot litter addition on the performance of seven Impatiens species grown in a two‐phase garden experiment.Soil conditioning negatively affected plant performance, which was at least partly explained by nutrient depletion. Root litter addition affected plant performance negatively and the results suggest that biotic effects such as pathogen transmission via the root litter played a role. The effects of root litter addition were more pronounced in control soil which, contrary to the conditioned soil, supposedly did not accumulate pathogens during the conditioning phase. Shoot litter addition increased soil nutrient levels, but had no impact on plant performance. However, presence of shoot litter aggravated the negative effects of root litter, probably due to increased amounts of nutrients available for soil biota and thus their faster growth and intensified effect on the plants.Overall, our study suggests that root and shoot litter have contrasting roles in plant–soil interactions and understanding their separate and interactive effects together with effects of soil conditioning is crucial for assessing the complexity of PSF.

Responses of soil microbial carbon use efficiency to warming: Review and prospects

Microbial carbon use efficiency (CUE) is an important factor driving soil carbon (C) dynamics. However, microbial CUE could positively, negatively, or neutrally respond to increased temperature, which limits our prediction of soil C storage under future climate warming. Experimental warming affects plant production and microbial communities, which thus can have a significant impact on biogeochemical cycles of terrestrial ecosystems. Here, we reviewed the present research status of methods measuring microbial CUE and the response of microbial CUE to the changes of biotic and abiotic factors induced by warming. Overall, current measurement methods mainly include metabolic flux analysis, calorespirometry, stoichiometric model, 13C and 18O labeling. Differences in added substrate types can lead to an overestimation or underestimation on microbial CUE, particularly when using the 13C labeling method. In addition, changes in the dominant microbial community under warming may also affect CUE. However, there is still uncertainty in CUE characteristics of different microorganisms. Microbial CUE is generally decreased under warming conditions as microbes are subjected to water stress or soil labile organic matter is much more depleted compared to ambient conditions. In contrast, considering that warming increases soil nutrient availability, warming may enhance microbial CUE by alleviating nutrient limitations for microbes. In conclusion, the response of microbial CUE to warming is more complex than expected. The microbial growth and physiological adaptation to environmental stress under warming is one of the main reasons for the inconsistence in microbial CUE response. Finally, we propose five aspects where further research could improve the understanding of microbial CUE in a warmer world, including using new technologies, establishing multi-factor interactive experiments, building a network of experimental research platform for warming, and strengthening studies on response of CUE to warming at different soil depths and on different temporal scales.

Effects of rice stalks mulching combined with green manure (<italic>Astragalus smicus </italic>L.) incorporated into soil and reducing nitrogen fertilizer rate on rice yield and soil fertility

<p id="C3">Planting green manure and straw retention is an effective measure to improve soil fertility. Two-year field experiment were conducted to assess the effects of reduced nitrogen rate under the rice straw mulching combined with planting green manure (<italic>Astragalus sinicus </italic>L.) at full bloom stage on rice yield, yield components, and soil nutrient availability in Hantai district, Hanzhong city, Shaanxi province from 2018 to 2020. Five treatments were assigned: (1) CK, winter fallow, no straw mulching, no fertilization; (2) NPK, winter fallow, no straw mulching, conventional nitrogen fertilizer rate; (3) GRN1, planting green manure in winter, rice straw mulching with conventional N fertilizer rate; (4) GRN2, planting green manure in winter, rice straw mulching with 80% conventional N rate; (5) GRN3, green manure planting in winter, rice straw mulching with 70% conventional N rate. The results showed that: (I) rice yield (Quanxiangyou 1521) of GRN1 was 10,047 kg hm^-2, which was higher 6.7% than that of NPK, and GRN2 and GRN3 had marginal effects in 2019. Moreover, the yield (Huanghuazhan) of GRN2 and GRN3 were significantly higher than that of NPK by 6.6% and 5.8% in 2020, respectively. Compared with CK and NPK, the rice straw mulching combined with planting green manure significantly enhanced the rice yield by 67.9%-83.0% and 2.8%-6.7%, respectively. (II) Planting green manure combined with rice straw mulching increased soil organic carbon content and available P content in 0-20 soil layer. Compared with NPK treatment, soil organic carbon and available P content of GRN2 increased 6.8%-13.2% and 9.9%-12.6%, respectively. Correlation analysis indicated that rice yield was significantly correlated with plant height, fresh weight per plant, fresh root stubble weight, filled grain number per panicle, and 1000-grain weight. Compared with NPK, GRN2 significantly increased effective panicle, effective grain number per panicle by 13.0%-29.3% and 4.5%-14.3%, respectively. Meanwhile, GRN2 significantly increased plant height, fresh weight per plant, and root fresh weight by 10.4%, 23.6%, and 30.0%, respectively. In conclusion, rice stalks mulching combined planting green manure with 20% reduced nitrogen rate can improve rice yield and agronomic performance, enlarge soil carbon sequestration capacity, and increase soil nutrients availability, which is a green rice cultural practice adapted to Hanzhong area.

Penerapan Biogas Guna Mengurangi Pencemaran Lingkungan di Kelompok Tani Ternak

This biogas technology program aims to reduce environmental pollution due to the smell of livestock manure and, at the same time, reduce the household economic costs of the farmer group community to buy LPG. The service method is by providing education to farmer groups about the cultivation of beef and dairy cattle, manure as a source of energy and fertilizer, and demonstration plots for biogas production. As the result of the dedication to making Biogas with a capacity of 12 m3, the digester starts to produce gas on the 14th day after being filled with cow dung. The economic value of cooking using Biogas is that it saves rupiah by not buying LPG gas, so on average, it holds 4-5 3 kg LPG cylinders per week or 16-20 LPG cylinders per month. The economic value saved is IDR 320,000 – 400,000 per family per month that uses this biogas fuel. Farmer groups use biogas waste as fertilizer for vegetables and corn. Three main benefits are felt, Biogas as a substitute for LPG, which the community has used. The by-product of Biogas has been used as organic fertilizer. From a social perspective, this program has also educated the public that livestock manure, which the community has considered waste, can provide economic and environmental benefits. The by-product of biogas technology which is processed into solid organic fertilizer, can increase soil nutrients, save costs on purchasing fertilizer, and increase people's income.

Synergistic remediation of copper mine tailing sand by microalgae and fungi

Biological soil crusts (BSCs) could strengthen soil particles, increase soil nutrients, and reduce soil erosion. However, available information on stabilizing mine tailing sand by induced BSCs is lacking. In this study, a native microalgae (i.e., Coelastrella sp.) and two fungi (i.e., Aspergillus sp. and Penicillium sp.) isolated from Cu mine tailing sand were inoculated onto the tailing sand in different manners. After being inoculated for 90 days, microorganisms could effectively colonize and form BSCs on the surface of the tailing sand, as proven by scanning electron microscopy images and growth parameters, and the dual inoculation of microalgae and fungi showed synergistic effects on the improved soil properties. Compared with the control treatment, the microorganism co-inoculation group had increased organic carbon, cation exchange capacity, soil moisture, sucrase activity, and microbial biomass carbon by 55.41%, 27.18%, 6.29%, 471%, and 216%, respectively; decreased pH from 9.09 to 8.95; and decreased bioavailable Cu content and bulk density by 15.43% and 6.30%, respectively. This finding indicated that the formation of BSCs could effectively improve the soil properties of mine tailing sand. The composition of dissolved organic matters analyzed by excitation–emission matrix showed that the increase in carbon content in tailing sand was predominantly caused by microalgae and fungi. These results indicated that the use of native microorganisms to construct biological crusts could effectively improve the properties of tailing sand and increase the nutrient content, and it could be used as a new method for tailing restoration.

Restriction of biosolids returning to land: Fate of antibiotic resistance genes in soils after long-term biosolids application

Although the utilization of biosolids in agricultural lands is widely considered as an effective way to improve resource reuse, the presence of antibiotic resistance genes (ARGs) severely restricts biosolids returning to fields. A 12-year long-term experiment with different biosolids application rates (from 0 to 36 t ha−1 yr−1) was conducted to study the effect of biosolids application on shaping ARGs in soil. Biosolids application significantly increased ARGs abundance in the soil, except for MBS treatment (9 t ha−1 yr−1 biosolids application). The abundance of ARGs in soil did not increase linearly with the dose of biosolids applied, but they were significantly (P < 0.05) positively correlated. A total of 173 subtypes were detected, among them mobile genetic elements (MGEs), aminoglycoside, and multidrug resistance genes were the most dominant types. Except for MBS treatment, most of the ARGs detected were enriched in amended soils after long-term continuous biosolids application. Specifically, tetPA, sul1, mefA, and IS6100 were highly enriched in all amended soils. In addition, biosolids application increased soil nutrients and heavy metals, and changed the soil microbial community, all of which affected ARGs formation. But MGEs may be a greater factor for shaping ARGs profiles than soil properties. Overall, controlling the rate of biosolid application is the key to reducing the accumulation and horizontal transfer of ARGs in soils.

Measuring Soil Quality Indicators under Different Climate-Smart Land Uses across East African Climate-Smart Villages

The present study assessed soil physical-chemical characteristics as reliable soil health indicators in six climate-smart land use types; agroforestry, community forest, cropland with soil and water conservation (SWC), crop land without SWC, grassland and control across climate-smart villages (CSVs) in Lushoto (Tanzania), Hoima (Uganda), Wote and Nyando (Kenya). Soils were sampled at three depths; 0–15 cm, 15–45 cm and 45–100 cm and then analyzed for bulk density (BD), pH, exchangeable bases (Ca, Mg, K, Na), extractable Fe, Mn, Zn, exchangeable acidity (ExAc), Electrical conductivity (EC), total carbon (TC), total nitrogen (TN) and cation exchange capacity (CEC). Land use types and sampling depths significantly affected soil properties (p &lt; 0.05), High bulk density (BD) was measured at 45–100 cm depth in grassland (1.47 g/cm3) and crop land (1.50 g/cm3) in Kenya and Tanzania, respectively. BD in Ugandan grasslands was statistically lower (p &lt; 0.05) than BD in other land use types at all depths. Soil pH of surface soil (0–15 cm) ranged from 6.67 ± 0.67 (agroforestry) to 6.27 ± 0.85 (grassland). Ex. bases (Ca, Mg, K and Na) and extractable Fe, Mn, Zn, ExAc, EC, TC, TN and CEC were significantly affected by land uses (p ≤ 0.05). Soil properties were significantly correlated, a positive correlation between silt % (p &lt; 0.01) and pH, sand and Ca (p &lt; 0.05). EC and pH, exchangeable Ca, exchangeable bases, exchangeable K and C: N ratio was observed. There was a negative correlation (p &lt; 0.05) between pH and clay. The study has shown that improving soil properties using land use systems leads to an increase in soil nutrients.

Long-term vegetable production significantly reduces the selenium adsorption in two typical plastic shed soils

Long-term vegetable production in plastic shed soil (PSS) and related soil management strategies stimulate the changes of soil properties and the mobilization of selenium (Se), causing risks to environmental soil quality and human health. Nevertheless, whether the greenhouse management (defined by the years of greenhouse vegetable production) and the greenhouse type have a synergistic effect on Se mobility in PSSs subjected to long-term vegetable production is still unclear. This study investigated the joint effects of greenhouse management and the properties of PSS on Se adsorption and desorption in soils collected from solar greenhouses (SG) and round arch plastic greenhouses (PG), which has been continuously cultivated respectively for 20 and 30 years in Tongshan County, Jiangsu Province, East China. Herein, we carried out a field survey coupled with batch experiments to investigate the adsorption and desorption behavior of Se in the SG and PG soils with different years of vegetable production. Results showed that greenhouse management had differentiated effects on soil properties and Se mobility in the two typical PSSs. Compared to the open field soils, long-term vegetable production generally increased soil nutrients (i.e., total P (TP), available P (AvP)), OM and Se desorption in the SG soil, while it significantly decreased Se adsorption in both typical PSSs. The soil pH had a downward trend with the increase of the years of vegetable production. The longer years of greenhouse vegetable production, the less Se adsorption capacity occurred in PSSs with annual decrease rates of 0.48 and 0.24 mg kg−1 yr−1 for the SG and PG soil, respectively, at 1.0 mg L−1 Se addition. Conversely, the ratio of Se desorption of the SG soils increased with longer vegetable production. The results of partial least squares regression (PLSR) explained the differences in Se adsorption and desorption between the SG and PG soil due to the changes in soil properties caused by the greenhouse management and greenhouse type. The fewer Se application is therefore recommended in the SG soils than in the PG soils after long-term greenhouse vegetable production.

Conservation and Conventional Vegetable Cultivation Increase Soil Organic Matter and Nutrients in the Ethiopian Highlands

Agriculture in Africa is adversely affected by the loss of soil fertility. Conservation agriculture (CA) was introduced to curb the loss of soil fertility and water shortages and improve crop productivity. However, information on how CA practices enhance soil quality and nutrients is scarce in the sub-Saharan Africa context. The objective of this study was to investigate the effects of CA and conventional tillage (CT) on soil organic matter and nutrients under irrigated and rainfed vegetable on-farm production systems. During the dry and wet monsoon phases in the northern Ethiopian Highlands, a four-year experiment with CA and CT was carried out on ten vegetable farms under rainfed and irrigated conditions. Although the increase in concentration of organic matter in CA was generally slightly greater than in CT, the difference was not significant. The average organic matter content in the top 30 cm for both treatments increased significantly by 0.5% a−1 from 3% to almost 5%. The increase was not significant for the 30–60 cm depth. The total nitrogen and available phosphorus concentrations increased proportionally to the organic matter content. Consequently, the extended growing season, applying fertilizers and livestock manure, and not removing the crop residue increased the nutrient content in both CA and CT. The increase in CA was slightly greater because the soil was not tilled, and hay was applied as a surface cover. Although CA increased soil fertility, widespread adoption will depend on socioeconomic factors that determine hay availability as a soil cover relative to other competitive uses.

Effects of Leonardite Amendments on Vineyard Calcareous Soil Fertility, Vine Nutrition and Grape Quality.

Vineyard calcareous soils are usually low in organic matter, which makes them prone to physical, chemical, and biological degradation. Besides, these soils are also usually poor in various nutrients in plant-available form, e.g., iron. To make up for this lack of soil fertility, on the one hand, manures, and on the other, iron chelates are usually used. However, the soil application of these materials is not free from problems, and other amendments based on leonardites could be advantageously used as an alternative. Therefore, two organic amendments, one leonardite alone (1 Mg/ha), and the other leonardite (1 Mg/ha) plus ferrous sulphate heptahydrate (0.5 Mg/ha), were tested for three years in a commercial vineyard calcareous plot under Mediterranean climate. The effects of these amendments on soil fertility, plant nutrient contents, and berry quality were studied against a control of bare soil by means of a fully randomized trial with three repetitions per treatment. Soil organic matter (SOM) increased as a consequence of both leonardite treatments, but much more than expected on the basis of a simple mass transfer from the amendments. With the ferrous-sulphate-heptahydrate-supplemented leonardite, the increase in SOM was noticeably higher. This is explained on the basis of nutrient quantity and intensity-pH-related effects, which increased soil nutrient plant-availability and presumably enhanced vine root growth. In response to the higher plant availability of nutrients, the petiole nutrient concentrations were observed to increase under the leonardite treatments. However, only a trend to increase potassium in petioles and in grape must, linked to a decrease of grape must pH, was observed in harvest quality under the leonardite treatments. Leonardite and adequately supplemented leonardite seem to have potential for increasing SOM contents and nutrient plant-availability, thus improving the soil fertility of vineyard calcareous soils.

Aeration increases soil bacterial diversity and nutrient transformation under mulching-induced hypoxic conditions

Soil oxygen (O2) deficiency induced by organic mulching is easy to overlook. Aeration has been shown to potentially alleviate soil hypoxia stress. However, the responses of soil bacterial communities to such mulching-induced hypoxic conditions and aeration remain elusive. Therefore, a three-year field experiment, consisting of mulching (T1), mulching with aeration (TA1, poor aeration; TA2, strong aeration), and no-mulching (CK) treatments, was conducted in bamboo (Phyllostachys praecox) plantations. According to our results, the strong aeration treatment (TA2) alleviated soil acidification, increased soil nutrient availability, and significantly increased soil O2 content by 18.44% (P < 0.05) when compared with T1. In addition, TA2 significantly increased soil β-glucosidase, invertase, urease, and acid phosphatase activities compared with CK and T1 (P < 0.05). The alpha diversity indices with TA2 treatment were the highest, indicating that aeration increased the species richness and diversity of bacteria. The changes in bacterial community composition associated with TA2 treatment (i.e., an increase in Firmicutes, Verrucomicrobia, and Faecalibacterium abundance and a decrease in Chloroflexi and Bradyrhizobium abundance) were mainly related to nutrient and O2 content. Mantel Test results suggested that soil O2 content and temperature were the key factors shaping bacterial community composition. Structural equation modeling revealed that soil O2 content had a positive and direct influence on bacterial community diversity. Functional annotation of prokaryotic taxa predicted that TA2 significantly increased the relative abundance of bacterial communities associated with nitrification, nitrogen fixation, and ureolysis. Our results demonstrated that optimal soil aeration conditions (17.60% of O2 content) could enhance the diversity and function of soil bacterial communities. Overall, the findings of this study could serve as a benchmark for alleviating soil hypoxia caused by organic mulches, which is important for increasing the functionality of nutrient cycling bacterial communities in the soil.

Mechanism of Intermittent Deep Tillage and Different Depths Improving Crop Growth From the Perspective of Rhizosphere Soil Nutrients, Root System Architectures, Bacterial Communities, and Functional Profiles.

Long-term conventional shallow tillage reduced soil quality and limited the agriculture development. Intermittent deep tillage could effectively promote agricultural production, through optimizing soil structure, underground ecology system, and soil fertility. However, the microecological mechanism of intermittent deep tillage promoting agriculture production has never been reported, and the effect of tillage depth on crop growth has not been explored in detail. In this study, three levels of intermittent deep tillage (30, 40, and 50 cm) treatments were conducted in an experimental field site with over 10 years of conventional shallow tillage (20 cm). Our results indicated that intermittent deep tillage practices helped to improve plant physiological growth status, chlorophyll a, and resistance to diseases, and the crop yield and value of output were increased with the deeper tillage practices. Crop yield (18.59%) and value of output (37.03%) were highest in IDT-50. There were three mechanisms of intermittent deep tillage practices that improved crop growth: (1) Intermittent deep tillage practices increased soil nutrients and root system architecture traits, which improved the fertility and nutrient uptake of crop through root system. (2) Changing rhizosphere environments, especially for root length, root tips, pH, and available potassium contributed to dissimilarity of bacterial communities and enriched plant growth-promoting species. (3) Functions associated with stress tolerance, including signal transduction and biosynthesis of other secondary metabolites were increased significantly in intermittent deep tillage treatments. Moreover, IDT-30 only increased soil characters and root system architecture traits compared with CK, but deeper tillage could also change rhizosphere bacterial communities and functional profiles. Plant height and stem girth in IDT-40 and IDT-50 were higher compared with IDT-30, and infection rates of black shank and black root rot in IDT-50 were even lower in IDT-40. The study provided a comprehensive explanation into the effects of intermittent deep tillage in plant production and suggested an optimal depth.

Effects of Long-term Fertilization on Soil Nutrient Characteristics and Microbial Resource Restrictions in a Terrace on the Loess Plateau

Long-term fertilization has an important effect on soil fertility and soil microbial activity. In order to explore the effects of long-term fertilization on soil extracellular enzyme activities and nutrient characteristics in a terrace on the Loess Plateau, we based our investigation on the long-term nutrient localization plot of Ansai Soil and Water Conservation Experimental Station, Chinese Academy of Sciences. We measured the soil physicochemical properties, microbial biomass, and extracellular enzyme activities of six fertilization treatments, which included no fertilization (CK); manure and nitrogen fertilization (MN); manure and phosphate fertilization (MP); manure, nitrogen, and phosphate fertilization (MNP); manure (M); and nitrogen and phosphate fertilization (NP). The results showed that all fertilization treatments significantly increased soil nutrient content and soil extracellular enzyme activities compared with that in CK. Correlation analysis showed that extracellular enzyme activity and soil physicochemical properties had an extremely significant correlation. The redundancy analysis indicated that soil nutrient and soil microbial biomass could explain 79.66% and 74.87% of the variation in soil extracellular enzyme activity and its stoichiometric ratio, respectively. Thus, the effects of fertilization on soil fertility were primarily through influencing soil extracellular enzyme activities indirectly. M, MN, MP, and MNP significantly improved soil organic carbon (SOC); soil total nitrogen (STN); and carbon (C), nitrogen (N), and phosphorus (P) source enzyme content; however, MNP changed the soil pH, which had an inhibitory effect on microbial activities. Vector analysis showed that the microbial communities of all treatments were in the condition of P limitation. Although MNP could alleviate the extent of P limitation, there was no significant difference between M and MP. Our study indicated that long-term application of manure[7500 kg·(hm2·a)-1]could meet the nutrient requirements of dryland crop growth, and long-term application of manure combined with phosphorus fertilization could alleviate the resource constraints faced by microorganisms. Consequently, our results provide a new insight into improving regional nitrogen excess.

Bioorganic and silicon amendments alleviate early defoliation of pear trees by improving the soil nutrient bioavailability, microbial activity, and reshaping the soil microbiome network

Pear trees with severe early defoliation usually suffer from weakened aboveground growth and a serious decrease of fruit quality and yield. Soil fertility and its microbial community and functional activity are significant factors impacting plant growth and yield, which also might be the very factors that influence the early defoliation of pear trees. To address the problems caused by chemical fertilizers, bioorganic fertilizer (BIO) and silicon amendment (SOA) are increasingly used as amendments to improve soil microbial activity and increase soil nutrient availability. However, how effective BIO and SOA are at improving the health of soils and reducing early defoliation remains unclear. Here, we conducted a 4-year field experiment (2016–2019) in a 25-year-old ‘Cuiguan’ pear orchard in Jianning county, Fujian province, comparing local custom fertilization (CK), local custom fertilization supplemented with SOA (CK-SOA), BIO, and BIO supplemented with SOA (BIO-SOA). At the end of the 4-year study we found that BIO and BIO-SOA treatments resulted in reduced leaf nitrogen content and increased leaf potassium (K), calcium (Ca), silicon (Si), and manganese (Mn) content. BIO and BIO-SOA treatments also resulted in a 50% reduction of the early deciduous rate and a 47% increase in pear yield. Compared with CK treated soil, BIO and BIO-SOA treated soils had higher nitrate nitrogen content (NO3−-N), available Si, Fe, Mn, and Zn content, and significantly improved microbial biomass nitrogen content (MBN), geometric mean enzyme activity (GMEA) and ecosystem multifunctionality (EMF). Network analysis revealed that BIO and BIO-SOA treatments had significantly altered the bacterial and fungal community composition in the orchard soil. Redundancy analysis (RDA) and the Mantel test indicated that soil available K, exchangeable Ca and Mg, and available Si, Fe, Mn and Zn content were the main factors influencing bacterial and fungal communities. The increased nutrient availability (e.g., NO3−-N and microelement contents), MBN, GMEA and EMF had negative effects on the early defoliation rate. Random Forest model identified soil available Si content, microbial biomass nitrogen content, EMF, and GMEA as the main predictors of early defoliation rate. Overall, this study demonstrates that application of BIO or BIO mixed with SOA can alleviate the early defoliation rate of pear trees by increasing the availability of microelements, microbial functional activity, and changing the soil microbial community composition.

Bio-Based Waste’ Substrates for Degraded Soil Improvement—Advantages and Challenges in European Context

The area of degraded sites in the world is constantly expanding and has been a serious environmental problem for years. Such terrains are not only polluted, but also due to erosion, devoid of plant cover and organic matter. The degradation trends can be reversed by supporting remediation/reclamation processes. One of the possibilities is the introduction of biodegradable waste/biowaste substrates into the soil. The additives can be the waste itself or preformed substrates, such composts, mineral-organic fertilizers or biochar. In EU countries average value of compost used for land restoration and landfill cover was equal 4.9%. The transformation of waste in valuable products require the fulfillment of a number of conditions (waste quality, process conditions, law, local circumstances). Application on degraded land surface bio-based waste substrates has several advantages: increase soil organic matter (SOM) and nutrient content, biodiversity and activity of microbial soil communities and change of several others physical and chemical factors including degradation/immobilization of contaminants. The additives improve the water ratio and availability to plants and restore aboveground ecosystem. Due to organic additives degraded terrains are able to sequestrate carbon and climate mitigate. However, we identified some challenges. The application of waste to soil must comply with the legal requirements and meet the end of use criteria. Moreover, shorter or long-term use of bio-waste based substrate lead to even greater soil chemical or microbial contamination. Among pollutants, “emerging contaminants” appear more frequently, such microplastics, nanoparticles or active compounds of pharmaceuticals. That is why a holistic approach is necessary for use the bio-waste based substrate for rehabilitation of soil degraded ecosystems.

Changes in plant communities and soil attributes in the "Cousteau's whale bone skeleton" tourist attraction area in Keller Peninsula after 48 years.

Ice-free areas of Antarctica represent an important study region that helps us understand how human activity affects plant communities and soil properties. The goal of this study was to determine the changes in plant composition and soil properties around a whale bone skeleton (WB) near Ferraz Station, King George Island, Antarctica from 1972 to 2020 (48 years). The WB was assembled in 1972 by Jacques-Yves Cousteau and his team. It is located in a large moss field and visited by many tourists. We studied the plant composition and development based on historical and recent photographs and phytosociological studies from 1986 to 2020. The soil was sampled in February 2009 to determine general properties. The results showed that human activity surrounding the WB directly affected the plant community composition and soil properties. The Syntrichia cushions were positively affected by the calcium deposits from bone dissolution. The principal component analysis revealed that mineralization of the bones increased soil nutrient assembly. A strong phosphatization process was observed in the WB area, similar to that in ornithogenic soils. The WB on the marine terrace enhanced soil fertility and changed the plant community.

Attributes of Farm Income Operating on Conservation Agriculture: TheMultivariate and ANN Analytics

Conservation agriculture (CA) is the combination of environmental management, modernand scientific agriculture, which employs farmers’ ability to utilize, innovate, and adapt tochanging situations, as well as their holistic acceptance of knowledge along with ensuringsustainability. Farm-level adoption of CA is related to reduced labour and agricultural inputs,more consistent yields, and increased soil nutrient exchange capacity. A good quality landyields good results to everyone, confers good health on the entire family, and causes growthof money, cattle, and grain. The present study depicts hard evidences by identifying markervariables impacting income augmentation through conservation agriculture. A score of 50farmers has been selected from two blocks of Cooch Behar district of West Bengal, bynon-probability snowballing sampling techniques with a total of eighteen independentvariables along with income from major crop is used as the dependent variable through astructured interview schedule. A basket of multivariate analytical techniques has been appliedalong with Artificial Neural Network (ANN) as well. The results depict that a blend ofdiversified farming and farming experiences in CA contributed immensely to scale up incomefrom conservation agriculture approaches.