Organic Inorganic Fertilizers Research Articles

Risk Assessment of Heavy Metal Accumulation in Cucumber Fruits and Soil in a Greenhouse System with Long-Term Application of Organic Fertilizer and Chemical Fertilizer

Combining organic and chemical fertilizers is a sustainable strategy for vegetable production. However, there is limited research concerning the risks associated with heavy metals (HMs) in greenhouse systems with long-term location application. A three-year investigation, conducted from 2021 to 2023, explored a fifteen-year field experiment with combinations of chemical fertilizer (CH), corn straw (SW) and pig manure (PM). Five treatments were evaluated: excessive fertilization (high CH and PM), conventional fertilization (normal CH), organic–inorganic fertilization (3/4CN + 1/4PN, 2/4CN + 2/4PN and 2/4CN + 1/4PN + 1/4SN). This study evaluated the risks associated with heavy metals (HMs) by analyzing and quantifying their concentrations in soil and cucumber fruits, as well as by calculating the bioconcentration factors (BCFs), the geo-accumulation index (Igeo), and both the non-carcinogenic and carcinogenic risks. The results indicated that excessive fertilization (CF) increased the concentrations of Cu and Zn in fruits, as well as the Igeo values of Cu, Zn, and Cd, and the non-carcinogenic Cu risk, while decreasing the BCFs of Cu and Zn. Organic–inorganic fertilization also elevated the Igeo values of Cu and Zn. Redundancy analyses confirmed a positive correlation between the soil concentrations of Cu and Zn and higher levels of available phosphorus contents (48.4%), alongside a lower pH (4.9%). The concentrations of Cu, Zn, and Cd in both soil and cucumber fruits increased linearly with the duration of application and amount of input. Although the combined application of CH with PM or SW did not significantly elevate the non-carcinogenic or carcinogenic risks associated with most heavy metals, the carcinogenic risks of Cd and As emerged as potential risk factors after 15 years of organic–inorganic fertilization. Utilizing a combination of CH with PM and SW as a fertilizer management strategy can effectively address both the control of heavy metal inputs in the facility and the safety and quality of cucumbers.

Different responses of soil bacterial community to plant-plant interactions under organic-inorganic fertilizers affect seedling establishment during subalpine forest succession.

Rhizosphere bacterial community as a valuable indicator of soil quality and function, has been widespread studied. However, little knowledge is about the response of bacterial communities to plant-plant interaction and different fertilizers during secondary forest succession. We conducted a field pot experiment applying organic and inorganic fertilizers to monocultures and mixed cultures of dominant plant species from mid- to late-successional stages (Salix oritrepha, Betula albosinensis, and Picea asperata), and investigated the responses of plant growth and rhizosphere bacterial communities. Results indicated that growth rate of plant height varied among plant species, but no significant differences were observed in soil bacterial diversity and composition among plant species or inter-specific interactions under control. Compared to control, inorganic fertilizer resulted in increases in plant growth and the relative abundance of Proteobacteria, Patescibacteria, Bacteroidetes and Gemmatimonadetes, while simultaneously leading to decrease in the relative abundance of Acidobacteria, Actinobacteria, Chloroflexi, Rokubacteria and Planctomycetes. When grown with other species, the bacterial communities in the mixture resembled those of S. oritrepha in singular monoculture under inorganic fertilizer treatment, but plant growth was not affected by interspecific interaction. Unlike inorganic fertilizer, organic fertilizer significantly affected bacterial communities and increased bacterial diversity, but did not alter the effects of plant-plant interactions on bacterial communities. It was also observed that organic fertilizer facilitated later successional species' growth (P. asperata and B. albosinensis) by the mid-successional species (S. oritrepha), ultimately facilitating secondary forest succession. In addition, plants at different successional stages harbor specific bacterial communities to affect their growth, and the bacterial communities contributed more than soil properties to the variations in the plant growth of S. oritrepha and P. asperata though the bacterial communities were regulated by soil factors. This finding highlights the significance of the rhizosphere bacteria on plant growth and plant community succession. It also emphasize the importance of considering both plant-plant interactions and diverse fertilizer types in forest restoration efforts and provide valuable insights into optimizing agronomic practices for secondary forest succession.

Possibility of processing phosphogypsum to obtain an alkalizing reagent

Relevance. The need to develop a technology for the disposal of solid and liquid industrial waste to obtain organic-inorganic fertilizer. The growth of industrial production is accompanied by an increase in waste. In modern society, considerable attention is paid to the problem of processing man-made waste to obtain demanded products. Phosphogypsum is the main by-product of the production of fertilizers and phosphoric acid, it is a multi-tonnage waste, its storage leads to the withdrawal of vast territories from circulation. Liquid waste from pig farms also needs to be processed into organic fertilizers. Aim. To study the process of heat treatment of phosphogypsum in the presence of a reducing agent to obtain an alkalizing reagent. This will make it possible to further organize processing liquid and solid agricultural and industrial waste and produce domestic organic fertilizers Methods. Heat treatment of phosphogypsum in the presence of a reducing agent, followed by the preparation of an aqueous suspension to obtain an agent that reduces the acidity of livestock effluents. The samples of heat-treated phosphogypsum obtained during the study were characterized by X-ray phase analysis, electron microscopy. Suspensions with different pH values were obtained on their basis. Results and conclusions. The authors have studied heat treatment of large-tonnage inorganic waste of the chemical industry – phosphogypsum. It was found that the suspension of phosphogypsum heat-treated in the presence of a reducing agent has increased values of the hydrogen index, which can be used to obtain an alkalizing reagent for treating agricultural waste. The authors revealed the optimal technological modes of obtaining a reagent having the maximum pH value of the suspension: the amount of the introduced reducing agent is 0.16 mol/mol CaSO4, the heat treatment temperature is 1000 °C.

Long-term fertilization reshaped the accumulation of plant- and microbially-derived carbon by regulating biotic and abiotic factors in acidic paddy soil

Fertilization exerts a profound influence on the formation, turnover and stabilization of soil organic carbon (SOC). However, how long-term fertilization regulates the contribution of plant residues and microbial necromass to SOC sequestration in acidic paddy soil remains unclear. This study aimed to elucidate these mechanisms by determining plant and microbial biomarkers, i.e., lignin phenols and amino sugars, as well as carbon degradation genes in both topsoil (0–15 cm) and subsoil (15–30 cm) within the context of a 10-year paddy field experiment. We investigated four fertilization regimes: no fertilizers (control), chemical fertilizers applied alone (NPK), NPK combined with cattle manure (NPKM), and NPK combined with rice straw (NPKS). Compared to the control, integrated organic-inorganic fertilization increased SOC by 15–21 % and 14–19 % in the topsoil and subsoil, respectively. Specifically, NPKM and NPKS did not alter the contribution of total lignin phenols to SOC in the topsoil but increased that in the subsoil by 63 % and 26 %, respectively. SOC accumulation exhibited a positive correlation with the concentration of total lignin phenols but a negative correlation with the acid to aldehyde ratio of vanillyl, indicating selective preservation of vanillyls. However, NPKM and NPKS decreased the contribution of total microbial residual carbon (MRC) to SOC in the topsoil (13–16 %) but didn't alter that in the subsoil. The decreased MRC contribution of topsoil was mainly reflected in fungal MRC, implying that fungi played a pivotal role in regulating topsoil carbon accumulation. Correlation analyses indicated that soil biotic and abiotic factors jointly affected the sequestration of plant lignin phenols and microbial necromass, and topsoil carbon accumulated with the abundance ratio of hydrolytic to oxidative enzyme-coding genes increasing (r = 0.62, p < 0.05). Combined with Partial Least Squares Path Model, our study revealed that the accumulation of organic carbon in the topsoil was more influenced by plant-derived carbon, whereas in the subsoil, it was co-affected by both plant- and microbially-derived carbon.

Organic–Inorganic Fertilization Shifts Dissolved Organic Matter Chemodiversity in Runoff From Tropical Cropland: Roles of Soil Nutrient Stoichiometry

ABSTRACTDissolved organic matter (DOM) is a crucial quality indicator for water health. However, it remains unknown how organic–inorganic fertilization differently shifts the DOM chemodiversity in cropland‐impacted runoff, especially the roles of terrestrial nutrient stoichiometry. Here, a field experiment subjected to 7‐year history of four fertilization regimes, that is, unfertilized (CK), chemical fertilization (NPK), straw return (SR), and NPK + SR, was conducted to examine the quantity and chemodiversity of runoff DOM in tropical China. Moreover, the ecological relationships between runoff DOM properties and soil C:N:P stoichiometry were evaluated. Relative to the control treatment, the carbon content (DOC) of runoff DOM increased by 29.20% and 48.82% under SR and NPK + SR treatments, but remained unchanged in NPK treatment. Conversely, the DOM nitrogen content (TDN) only elevated in NPK treatment (262.58%). For DOM chemodiversity, SR treatment was rich in methyl carbon and protein‐like substances, but lacked fulvic‐/humic‐like compounds. NPK treatment increased the hydrophilic compounds like amino acids and polysaccharides, while reducing aromaticity. NPK + SR treatment enhanced DOM's aromaticity, molecular weight and humification due to the enrichment of quinone, ketone and fulvic‐like substances, possibly shaping an oligotrophic aquatic microbial community. Further study revealed that the occurrence of aromatic DOM was positively correlated with soil moisture content, TK (total potassium), total organic carbon and stoichiometric N:P ratio, indicating the contribution of terrestrial straw‐decomposed products. Inversely, the accumulation of hydrophilic substances (e.g., TDN) correlated positively with soil NO3‐N and C:P ratio, indicating the contribution of endogenous DOM.

Effects of fertilization applications on soil aggregate organic carbon content and assessment of their influencing factors: A meta-analysis

Fertilizer application plays an important role in agricultural soil organic carbon (SOC) and its sustainable management. However, there is a lack of consensus about the mechanisms regarding fertilizer application in the soil on the procedure of carbon sequestration and sink enhancement in the aggregates. In this study, the extent by which various fertilization treatments, fertilization durations, climate conditions, soil texture, and land-use types affected the organic carbon (OC) content of different particle-size aggregates was quantitatively assessed using a meta-analysis of 696 treatment comparisons from 36 published studies. Based on the meta-analysis results, fertilization enhanced the OC contents of macroaggregates and clay and silt particles, particularly through replenishing organic material. Long-term fertilization increased the OC content of macroaggregates (>0.25 mm), while the OC content of the clay and silt particles (<0.053 mm) reached a maximum at 15.4 years of fertilization, after which it reached carbon saturation. Organic fertilizer effectively increased the OC content of small macroaggregates (0.25–2 mm) and microaggregates (0.053–0.25 mm) at lower temperatures and precipitation. Compared with inorganic fertilization, combined organic–inorganic fertilization increased OC contents of all sizes of aggregates in sandy or clay loam soils, but decreased OC contents of microaggregates and clay and silt particles in silt loam soils. All fertilization treatments increased the OC content of all particle-size aggregates in upland soils. In contrast, inorganic fertilization and mixed organic–inorganic fertilization reduced the OC content of microaggregates (0.053–0.25 mm) and clay and silt particles (<0.053 mm) in paddy field soils. In conclusion, the application of organic fertilizers is more conducive to the accumulation of OC in agricultural soil aggregates. Whereas the limiting factors for the accumulation of OC content in soil aggregates vary under different conditions, organic fertilizer inputs should be given more consideration, especially in dryland and coarse-textured soils.

Enhancing phosphorus transformation in typical reddish paddy soil from China: Insights on long-term straw return and pig manure application via microbial mechanisms

Effective utilization of organic resources to activate residual phosphorus (P) in soil and enhance its availability is crucial for mitigating P resource scarcity and assessing the sustainable use of P in agricultural practices. However, the mechanisms through which organic resources affect soil P conversion via microorganisms and functional genes remain unknown, particularly in long-term organic-inorganic agricultural systems. In this study, we examined the impact of combined organic-inorganic fertilizer application on P availability, carbon (C) and P cycling genes, and microbial communities (bacterial and fungal) in reddish paddy soil based on a 42-year field experiment. The results indicated that long-term straw returning and pig manure application significantly augmented soil organic carbon (SOC), Olsen-P, microbial biomass carbon (MBC), microbial biomass phosphorus (MBP), enzyme-P, and CaCl2-P levels in paddy soils. Furthermore, these practices increased the abundance of soil C degradation genes, reduced the abundance of soil P cycling genes, and altered microbial community structure and network complexity. Notably, Module #3 ecological clusters in the fungal ecological co-occurrence network were significantly correlated with P cycling genes. Finally, our study demonstrated that long-term straw returning and pig manure application in paddy fields facilitated two robust and contrasting predictive relationships between C degradation (negative relationship) and P cycling (positive relationship) genes, respectively, and enzyme-P and HCl-P changes to improve soil P availability. This study can enhance our understanding of the role of soil microbial communities and functional genes in mediating P transformation to decipher the enhancement in P application efficiency driven by organic resources in reddish paddy soils.

The improvement of soil properties in rice cropping systems using an integrated fertilization method to increase rice yield

AbstractThe global food crisis provides an impetus for agricultural green transformation via optimized fertilization methods. While organic substitution, green manure incorporation, and targeted fertilization sites have individually shown promise in enhancing rice yield, there is still a gap between optimized fertilization methods and achieving sustainable rice production. To explore the factors influencing rice yield across different fertilization strategies, we conducted a field experiment in Southern China encompassing five treatments, such as CK (no N input), RN (broadcasting urea with recommended N rates), RON (broadcasting organic–inorganic fertilizer with recommended N rates), RONS (side‐deep placement of organic–inorganic fertilizer with recommended N rates), and RONSA (coupled RONS with Azolla [Azolla pinnata R. Brown]). Using a Minimum Data Set approach, we identified the primary variables influencing soil properties and rice production, with a focus on soil physicochemical characteristics and bacterial communities. Further, the soil properties index (SPI), calculated by multiplying the linear score with the weight of each variable, served as an indicator of soil properties variations. Our findings revealed that RONSA significantly increased the SPI by 21.1% compared with RN, predominantly because of higher soil labile organic carbon (LOC) and available N (SAN) fractions (p &lt; .05). N uptake in rice plants (23.9%–28.4%) increased dramatically under RONSA leading to higher rice yield (11.0%–16.9%) and NUE (30.2%–36.1%) than RN (p &lt; .05). The enhancement in soil properties, characterized by increased LOC, SAN fractions, and bacterial community diversity, was essential in boosting rice yields, with dissolved inorganic N emerging as the dominant contributor. In summary, our results highlight the effectiveness of integrated fertilization approaches in enhancing soil properties, subsequently leading to improved rice yields and NUE. This fertilizer strategy holds promise for guiding field fertilization practices and advancing sustainable rice production.

Partial Substitution of Chemical N with Solid Cow Manure Improved Soil Ecological Indicators and Crop Yield in a Wheat–Rice Rotation System

Alternative fertilizers are essential to minimizing the deteriorating effects of chemical fertilizers on soil and water quality/health. Accordingly, the present work investigated the effects of combined organic–inorganic fertilization (COIF) on wheat and rice yields, soil nutrients, and soil Cd accumulation. Hence, seven different treatments were set up: control (CK); conventional fertilization (CF); adequate fertilization (OF); organic fertilizer replacing 25% (T1) and 50% (T2) of OF; and organic nitrogen (N) replacing 25% (M1) and 50% (M2) of OF-N. Overall, significant increases occurred in the yields of COIF crops. Compared with the CF, the highest wheat and rice yields happened in the M1 treatment (with a difference of approximately 18.5%) (p &lt; 0.05). COIF slightly alleviated soil acidification, and improved the cation exchange capacity (CEC) of the study soils. Furthermore, COIF treatments significantly increased the contents of total phosphorus, total potassium, available phosphorus, and available potassium by 6.35 to 16.9%, 3.17 to 10.9%, 5.53 to 28.7%, and 2.6 to 12%, respectively (p &lt; 0.05). Nevertheless, negligible increases took place in the Cd content of COIF soils compared with that of the CK. Altogether, our results concluded that 25% replacement of OF-N by organic N (M1) effectively improved the fertility/ecological sustainability of the study soils.

Optimal organic-inorganic fertilization increases rice yield through source-sink balance during grain filling

Context or problemOrganic-inorganic fertilization has been proven to maintain sustainable rice production. However, the chemical nitrogen (N) fertilizer reduction and its underlying mechanisms have not been revealed under organic-inorganic fertilization. Objective or research questionThe objective of this study was to quantify how organic-inorganic fertilization affected rice yield and the source-sink relationship during grain filling. MethodsA two-year field experiment was conducted during the rice growing seasons of 2021 and 2022, with two organic fertilizer levels (-M, 0 kg ha−1 and +M, 3000 kg ha−1), and five N rates (N0: 0 kg ha−1, N90: 90 kg ha−1, N180: 180 kg ha−1, N270: 270 kg ha−1, N360: 360 kg ha−1). Rice yield and yield components, agronomic N use efficiency (AE), leaf area index (LAI), chlorophyll content, and source-sink traits were examined. ResultsCompared with -M treatment, organic-inorganic fertilization increased rice yield. Rice yield for N180 + M was comparable to that for N270 and N360 in two years, while AEtotal N significantly increased 22.29% compared to N360. LAI and SPAD value were also increased under organic-inorganic fertilization. The rice sink growth and source activity increased with the increase of N rate and organic fertilization. Compared with -M treatment, organic-inorganic fertilization showed higher sink growth and source capacity. Rice yield was source-limited under -M and +M treatments, while organic fertilizer application could increase the source/sink ratio. Meanwhile, we found that the source/sink ratio was significantly positively correlated with rice grain yield. Partial least squares path modeling (PLS-PM) showed that organic-inorganic fertilization optimized source-sink balance by increasing source capacity and sink growth, thereby increasing the rice yield. ConclusionsThe high rice yield of organic-inorganic fertilizer over N fertilizer could be explained by its higher sink growth and source capacity. Considering comprehensively yield, AE, and source-sink balance, a combination of N rate of 180 kg ha−1 and organic fertilization of 3000 kg ha−1 was the optimal organic-inorganic fertilization management practice. Implications or significanceThe study provides a scientific basis for chemical N reduction in rice production and contributes to the promotion of agriculture sustainable development.

Contrasting fertilization response of soil phosphorus forms and functional bacteria in two newly reclaimed vegetable soils

Fertilization is a pervasive approach to agricultural production enhancing vegetable nutrients such as phosphorus (P) absorption. However, unreasonable fertilization strategies result in high levels of residual P in vegetable planting systems. To better understand the mechanisms of soil phosphorus dynamics responding to inorganic/organic fertilization, we conducted a 3-year field experiment in two newly reclaimed vegetable fields in southern China. The results revealed that soil Olsen-P in CF (mineral fertilization) and OF (Combined application of organic and inorganic fertilizers) increased by approximately 210.6 % and 183.6 %, respectively, while stable P proportion decreased by approximately 9.2 % and 18.1 %, respectively, compared with CK. Combined application of organic and inorganic fertilizer increased the proportion of moderately labile P (NaOH-P) by 1–6 % in comparison with chemical fertilizer and facilitated the conversion from diester-P to monoester-P, indicating that applying pig manure enhanced the potential soil P bioavailability. Besides, organic-inorganic fertilization shaped a bacterial community with more connectivity and stability and changed keystone taxa related to the P transformation of the network. Phenylobacterium, Solirubrobacter, and Modestobacter were regarded as core genera for mobilizing soil phosphorus. However, residual P content in newly reclaimed soils under fertilization, especially for chemical fertilizer, remained non-negligible and may cause potential environmental risks. The partial least squares path modeling results demonstrated that fertilization management had both direct and indirect positive effects on P fraction through the improvement of soil nutrients e.g. total N and soil organic carbon, and bacterial community, while soil properties mainly determined the variation of soil P species. Our results provide comprehensive insights into the current status of legacy P forms and the vital role of fertilizer, key soil properties and bacteria in P dynamics in newly reclaimed vegetable field.

Responses of maize root morphology and soil available nutrient to fertilizer types in a coal mine reclamation area

The impact of different fertilizer types with equal nitrogen levels on maize root morphology and soil available nutrient is needed, especially in coal mine reclamation areas. After 9-year fertilization, the maize root biomass, length, and surface area of the organic–inorganic fertilization (OF) treatment were significantly higher than those of other treatments. The contents of available phosphorus and available potassium were 18.46 and 176 mg·kg−1, respectively, under OF treatment, which were significantly higher than those under other treatments. Our findings indicate that the fertilizing effect of OF treatment is effective for soil reclamation in mining areas.

Unveiling the maize-benefit: Synergistic impacts of organic-inorganic fertilizer cooperation on rhizosphere microorganisms and metabolites

Maize, an indispensable staple crop, plays a vital role in ensuring human food security. To shed light on the effects of different fertilizer management modes on maize growth, as well as rhizosphere bacterial populations and metabolites, we employed high-throughput sequencing and non-targeted metabolomics technology. Experimental treatments comprised: CK (no fertilizer), CF (single chemical fertilizer, N-P2O5-K2O), OF30 (30 % organic fertilizer replacement), OF70 (70 % organic fertilizer replacement), and OF100 (100 % organic fertilizer, animal manure and humic acid as raw materials). Compared to the single chemical fertilizer, the dual fertilizer management resulted in a more stable bacterial network and a more complex metabolic system. Notably, under OF70 conditions, the rhizosphere soil exhibited greater prevalence of functional bacteria like Paenibacillus and Pseudoxanthomonas. This stimulation significantly activated biosynthesis processes like unsaturated fatty acids, plant hormone synthesis, and plant secondary metabolite production. Through correlation mining of differential metabolites and differential bacteria, as well as weighted gene co-expression network analysis (WGCNA), we revealed a consistent correlation trend between bacterial population abundance and changes in metabolite content under dual fertilization. The dual fertilizer approach established a more intricate regulatory relationship between plants, bacteria and metabolites, indicative of a more stable rhizosphere environment. Importantly, our findings on the superior growth performance of maize under OF70 conditions, coupled with microecological changes in the rhizosphere (bacteria and metabolites), provide valuable insights for advancing efficient maize cultivation and informing scientifically sound fertilizer management practices. Moreover, these results hold relevance for production considerations in other agricultural crops. However, it is crucial to further explore the generalizability of these findings in field conditions.

Comparison of organic eggplant yields under open-field and high tunnel production systems in Texas

High tunnel (HT) vegetable cultivation stands out as a superior choice when compared to open field (OF) production due to its numerous production benefits. However, intensive cultivation practices involving excessive use of inorganic fertilizer (IF) in HT production systems may lead to degradation of soil health, and ultimately poor crop yields. Therefore, this study investigated the effect of liquid organic fertilizer (LOF) and IF on growth and yield of eggplant (Solanum melongena L.) cultivars in HT and OF production systems. Two experiments were conducted in a split-split plot design with production systems (HT and OF) as main plot, fertilizers (LOF and IF) as sub-plot, and cultivars (‘Angela’ and ‘Jaylo’) as sub-sub plot factors. Throughout the growing season, daily average temperature and relative humidity were greater by 2 to 4 ​°C and 2 to 4%, respectively, under HT compared to OF conditions. In contrast, average daily light integral of HT decreased 18 to 24% compared to OF. Results from pooled growth and yield data of both experiments indicate HT produced 61% taller plants with 62% thicker stem diameter compared to OF. However, eggplant height and stem diameter did not differ significantly between fertilizer treatments or between cultivars. Due to a greater fruit count for each plant (63%) and average fruit weight (9%), total yield was 84% greater in HT compared to OF. Eggplant cultivar ‘Jaylo’ yielded 33% greater fruit count for each plant and 38% greater fruit yield compared to ‘Angela’ cultivar. However, no differences in fruit count, fruit weight, and the total yield were observed between LOF and IF. Results indicate that HT production offered a favorable microclimate which encouraged plant growth and greater fruit yield of eggplant compared to OF conditions. LOF and ‘Jaylo’ could be successfully used in organic eggplant production in HT and OF systems.

N2O Emissions from Saline Soils in Response to Organic–Inorganic Fertilizer Application under Subsurface Drainage

Organic fertilizer applications and subsurface drainage are two important measures for improving coastal saline soil; however, nitrous oxide (N2O) emissions from saline soil under a combination of these two measures are seldom evaluated. In this study, saline soil cultivated with sunflowers (Helianthus annuus L.) was employed as an experimental system. Prior to the experiment, the saline soils were buried with three different spacings (10 m (S1), 15 m (S2), and 20 m (S3)) of subsurface drainage pipes. The nitrogen nutrients that are needed by sunflowers came from two different nitrogen sources (organic and inorganic fertilizer), including six application schemes of either 100% organic fertilizer (100%OF), 75% organic fertilizer combined with 25% inorganic fertilizer (75%OF), 50% organic fertilizer (50%OF), 25% organic fertilizer (25%OF), 0% organic fertilizer (0%OF), and no fertilizer (CK). The results show that the cumulative N2O emissions from the treatments under S1, S2, and S3 throughout the entire growth period were 8.9–15.8, 9.5–17.5, and 10.1–17.6 kg ha−1, respectively. A smaller spacing between adjacent drainage pipes or a higher replacement proportion of organic fertilizer reduced the accumulative N2O emissions. The increased replacement of organic fertilizer decreased the soil salinity, whereas it increased the C/N ratio and total carbon content. The fertilization treatments significantly increased the nitrogen uptake of sunflower plants, with increase ranges of 18.1–47.2%, 8.6–40.5%, and 8.8–34.5% under S1, S2, and S3, respectively, compared with CK. The highest yield of sunflowers was achieved under S2 combined with 25%OF, reaching 3.82 t ha−1. Correlation analysis showed that the N2O emission flux was positively correlated with the soil salinity, crop yield, and crop nitrogen uptake, whereas it was negatively correlated with the total carbon, C/N ratio, and organic carbon content. We concluded that using 25% organic fertilizer instead of inorganic fertilizer was beneficial for reducing N2O emissions while maintaining the crop yield under subsurface drainage.

Effect of humus on photodegradation of quinclorac under different fertilization modes.

Humus is a specific kind of organic matter widely distributed in soils. The characteristics of humus have significant impacts on the fate of pollutants in the environment. In this study, we examined the effects of fertilization modes from rice rotation systems on the contents, spectral properties, photochemical activity, and photosensitization of quinclorac (QNC) of humic (HA) and fulvic acids (FA). The results showed that under the rice-vegetable rotation system, organic fertilizer treatment decreased the humification degree and molecular weight of HA, but increased the number of oxygen-containing functional groups and the abilities of photoproducing hydroxyl radical (HO·), singlet oxygen (1O2) and photosensitizing QNC, compared with chemical fertilizer treatment. Under organic fertilization mode, the molecular weight of FA was increased, but the number of redox functional groups and the abilities of photoinducing HO· and 1O2 and photosensitizing QNC were decreased. Under rice-shrimp cultivation system, organic-inorganic fertilizer treatment increased the humification degree, molecular weight, number of redox functional groups and oxygen-containing functional groups, and 1O2 photogeneration of HA, but decreased the abilities of photoproducing HO· and photosensitizing QNC, as compared with chemical fertilizer treatment. The humification degree and molecular weight of FA under organic-inorganic fertilization mode were increased, while the abilities of photoproducing HO· and 1O2 and photosensitizing QNC were decreased. In conclusion, organic fertilization could enhance the photochemical activity and photosensitizing efficiency of humus, and further promote the photodegradation of QNC in the environment.

Fertilizer management methods affect bacterial community structure and diversity in the maize rhizosphere soil of a coal mine reclamation area

BackgroundThe filling or mixed stack mode is a frequently used coal mine reclamation engineering technique that results in changes in soil microbial community structure and nutrient content, which lead to considerable deviations from the characteristics of restored coal mine reclamation areas that can be used for farming. Fertilization is an effective strategy for improving soil fertility in such areas; however, the response of soil bacterial communities, especially in the crop rhizosphere soil, to different fertilization techniques in such soils remains unclear. Therefore, we investigated the effects of different fertilization management methods, including no fertilizer, farmers' practice, inorganic fertilizer, organic fertilizer, and organic–inorganic fertilizer, on maize yield, rhizosphere soil bacterial community and diversity, soil physicochemical properties, and nitrogen cycle-related gene abundance (nifH, AOB, and nirS).ResultsThe results showed that organic–inorganic fertilizer treatment significantly improved maize yield. The relative abundance of the dominant phyla did not significantly differ between the treatment groups. However, the Chao 1 and Shannon indices of the bacterial community significantly changed between the no fertilizer and organic–inorganic fertilizer treatments. Notably, organic–inorganic fertilizer application significantly increased the copy numbers of nifH and nirS. Further, moisture, bulk density, and available phosphorus content were identified as the major driving factors responsible for the changes in bacterial community structure, diversity, and copy numbers of nifH, nirS, and AOB.ConclusionsThe results of this study revealed that organic–inorganic fertilizer application improved soil bacterial diversity and the copy numbers of nifH and nirS in maize rhizosphere soil. Therefore, we concluded that organic–inorganic fertilizer is an effective strategy for the restoration of maize rhizosphere soil properties and bacterial communities in coal mine reclamation areas.

Organic-inorganic fertilization promotes paddy soil macroaggregate organic carbon accumulation associated with key bacterial populations in subtropical China

Macroaggregate organic carbon (Macro-OC) accumulation in paddy soils is of great significance in promoting multiple agroecosystem services. However, the effects of different fertilization practices on Macro-OC accumulation in paddy soils at the regional scale have not been comprehensively investigated. Here, we conducted long-term fertilization field experiments at four sites, Taoyuan, Wangcheng, Jinxian, and Suzhou, in the subtropical area of China to reveal the effects of inorganic and organic-inorganic (OIF) fertilization on Macro-OC accumulation and its relationships with important microbial traits (the abundance ratio of GH48:cbhI genes and the richness of keystone bacterial taxa) in paddy soils. The results showed that long-term fertilization (particularly OIF) significantly increased the content of Macro-OC, which mainly consisted of particulate organic carbon (C). Organic-inorganic fertilization decreased the percentage of O-alkyl C but increased the percentages of alkyl, aromatic, and phenolic C. Organic-inorganic fertilization promoted the abundance of the bacterial cellulose-degrading gene GH48 retrieved from macroaggregates. The orders Anaerolineales, Bacillales, and Clostridiales were identified as keystone bacterial taxa in macroaggregates and were significantly correlated with the physical fraction and chemical structure of Macro-OC. Structural equation modeling revealed that fertilization-induced changes in soil pH and C:N ratio affected the richness of Anaerolineales, Bacillales, and Clostridiales, which was strongly associated with the increase of percentages of aromatic and phenolic C and further facilitated Macro-OC accumulation. Together, these results suggested that OIF promoted Macro-OC accumulation associated with key bacterial populations in paddy soils. The results provide an important basis for boosting soil C accrual in the subtropical rice-growing areas.

Integrating low levels of organic fertilizer improves soil fertility and rice yields in paddy fields by influencing microbial communities without increasing CH4 emissions

Although organic fertilizer is usually recommended for improving soil quality and crop yields, it inevitably enhances methane (CH4) emissions. Effective measures to mitigate CH4 emissions while ensuring crop yields are urgently needed. A two-year experiment was performed to examine the effects of organic-inorganic fertilizer combinations on CH4 emissions, the CH4-related microbial community, soil biochemical characteristics, and rice yields during dual rice growing seasons in 2020–2021 at two locations (i.e., Nanning and Yulin City, Southern, China). The treatments were as follows: no N fertilizer (Neg-CF), 100 % chemical fertilizer (CF) (Pos-CF), 60 % cattle manure (CM) + 40 % CF (High-CM), 30 % CM + 70 % CF (Low-CM), 60 % poultry manure (PM) + 40 % CF (High-PM), and 30 % PM + 70 % CF (Low-PM). CH4 fluxes and related functional microorganism abundances were investigated using the closed chamber method and molecular procedures, respectively. The addition of organic manure significantly improved rice grain yields and soil properties, including total nitrogen (TN), soil organic carbon (SOC), and pH compared to the Pos-CF. Similarly, integrating organic and inorganic fertilizers led to significant increases in seasonal CH4 emissions, global warming potential (GWP), and the abundance of CH4-related soil microbes. Average increases in SOC, TN, CH4 emissions, and GWP in the High-PM treatment relative to the Pos-CF were 44.7, 36.4, 20.6, and 24.4 %, respectively, in Nanning; and 28.9, 33.3, 23.4, and 20.8 % in Yulin City, averaged across the years. Moreover, co-fertilization resulted in the highest increase in methanogenic diversity and abundance relative to Pos-CF only. Applying high proportions of manure improved the abundance of methanogenic soil archaea related to CH4 production compared with the plots with low proportions of manure. Interestingly, lower manure amendments produced the highest rice grain yields and lowest CH4 emissions while maintaining high soil qualities. In addition, regression analysis exhibited that SOC was highly positively associated with CH4 emissions. Above all, controlling the proportions of organic manure and CF may be a feasible approach for enhancing rice yields and soil quality while mitigating CH4 emissions. Of the treatments tested, the combination of 30 % organic manure (i.e., CM or PM) with 70 % CF (urea) performed the best. This study showed that combining manure and CF at a 30:70 ratio was the most effective approach for improving soil health and rice yields while ensuring environmental sustainability.

Fertilization Highly Increased the Water Use Efficiency of Spring Maize in Dryland of Northern China: A Meta-Analysis

Water and fertilizer play an important role in crop growth in dryland areas. It is a necessity to improve the water use efficiency (WUE) of the crop once the water resource is limited. In northern China, where there is a wide shortage of water resources, it is therefore necessary to investigate how fertilization affects the WUE of spring maize and to quantify the effects. A total of 33 published peer-reviewed papers were collected, and a meta-analysis and random forest model analysis were performed with 364 WUE comparisons, aiming to explore the effects of fertilization on the WUE of spring maize and to clarify the optimal conditions for WUE under fertilizer management. The results showed that fertilization significantly increased the WUE of spring maize by 56.72% (P &lt; 0.01) when compared with non-fertilization. The WUE effect under the organic–inorganic fertilizer combination (MNPK) was approximately twice as high as that under inorganic fertilizer (NPK) or organic fertilizer (M). The greatest increase in WUE occurred at 0–100 kg ha−1 of nitrogen application (NA). Under environmental conditions including 7 ≤ mean annual temperature in the test year (T) ≤ 10 °C, 400 ≤ mean annual precipitation in the test year (P) ≤ 600 mm, and mean altitude (A) &gt; 1500 m, and soil conditions including 10 ≤ soil organic matter content (SOM) ≤ 14 g kg−1 and available phosphorus (AP) &lt; 5 mg kg−1, the fertilization optimally enhanced the WUE of spring maize when the agronomic measures of ridge–furrow planting (RFP) and mulching film (MF) were used. The random forest model analysis indicated that the influence factors (i.e., fertilizer regimes, environmental factors, soil factors, and agronomic measures) caused 65.62% of the variation in spring maize WUE effects, while in all influence factors, fertilizer types related to fertilizer regimes caused the most variation. The initial available potassium (AK) and available nitrogen (AN) of the soil were negatively correlated to the WUE effect, indicating that fertilization imposed a better effect on the WUE of spring maize when the soil was infertile. Fertilization significantly increased the WUE of spring maize, and organic and inorganic fertilizer application provided an effective measure for the sustainable development of spring maize in northern China. After clarifying the required conditions for fertilization increasing WUE, high-efficiency water use may be achieved.