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Chemical fertilizer has been excessively used for high yield of citrus around the world, especially in China; meanwhile, it deteriorates the citrus orchard soil environment. To resolve the conflict, the use of organic fertilizer provides a promising solution. However, the data about organic fertilizer used in citrus orchard is rarely available. Here, four treatments including CK (no fertilizer), CF (chemical fertilizer), OF + CF (chemical fertilizer reduction combined with organic fertilizer; application of N, P2O5, K2O fertilizer and organic fertilizer is 0.564, 0.236, 0.336 and 10 kg/plant), and BF + CF (chemical fertilizer reduction combined with bioorganic fertilizer; application of N, P2O5, K2O fertilizer and bioorganic fertilizer is 0.508, 0.320, 0.310 and 10 kg/plant) were performed in a ‘Ponkan’ (Citrus reticulata Blanco) orchard to evaluate the effect of organic fertilizer on citrus yield, growth, soil properties etc. when nutrients of fertilizer of each treatment were equal except CK. The data obtained in 2019 and 2020 showed that both OF + CF and BF + CF were beneficial to improve soil fertility (soil physicochemical and microbe properties) and citrus growth physiology (growth, nutrient and photosynthesis), alleviate NO3−-N leaching, and promote yields. Comprehensive evaluation indicated that BF + CF was more effective than OF + CF. Together, organic fertilizer has the potential to substitute partial chemical fertilizer with improvement in soil properties, growth physiology, and yield of citrus.

Biochar is a kind of organic matter that can be added into the soil as a soil amendment to improve its quality. What are the effects of using biochar on purple soil and soybeans? Can the use of biochar reduce the use of fertilizers? This is our concern. Therefore, we carried out this study. The objectives of our study were to evaluate the effects of biochar, inorganic and organic fertilizer application on plant growth, chlorophyll content, photosynthetic gas exchange, and yield of soybean as well as fertility and microbial community in purple soil, and to appraise the possible reduction rate of inorganic fertilizer under the biochar application. A pot experiment was conducted with three levels of biochar, two levels of inorganic fertilizer, and two levels of organic fertilizer in a randomized complete block. The results indicated that the low rate of biochar together with half rate of inorganic fertilizer and organic fertilizer increased the plant growth of soybean. Meanwhile, the chlorophyll content, root growth, and yield of soybean were increased by 16.61, 197.73, and 96.7%, respectively, with biochar compared with no biochar. The high rate of biochar with half rate of inorganic fertilizer and organic fertilizer can promote the exchange of photosynthetic gas in soybean, and the photosynthetic rate increased by 45.25% compared with the blank control. At the full pod stage, the nitrogen content, phosphorus content, and potassium content of the whole plant under the high rate of biochar were 28.35, 13.65, and 28.78%, respectively, higher than that of the blank control. The application of biochar increased nitrogen, phosphorus, and potassium uptake of soybean. The high rate of biochar with half rate of inorganic fertilizer and organic fertilizer can improve soil nutrient content and soil microbial community. Compared with no biochar treatments, total organic carbon (TOC) increased by 740.28%, and cation exchange capacity (CEC) increased by 54.17%. Phospholipid fatty acid (PLFA) increased by 65.22%, and all kinds of soil microorganisms increased to varying degrees. In conclusion, the application of biochar can reduce the use of organic and inorganic fertilizers, improve the agronomic traits and yield of soybean, and play a positive role in soil nutrients and soil microorganisms.

Fusarium wilt, caused by Fusarium oxysporum f. sp. cucumerinum J. H. Owen, results in considerable yield losses for cucumber plants. A bio-organic fertilizer (BIO), which was a combination of manure composts with antagonistic microorganisms, and an organic fertilizer (OF) were evaluated for their efficiencies in controlling Fusarium wilt. Application of the BIO suppressed the disease incidence by 83% and reduced yield losses threefold compared with the application of OF. Analysis of microbial communities in rhizosphere soils by high-throughput pyrosequencing showed that more complex community structures were present in BIO than in OF treated soils. The dominant taxonomic phyla found in both samples were Proteobacteria, Firmicutes, Actinobacteria and Acidobacteria among bacteria and Ascomycota among fungi. Abundance of beneficial bacteria or fungi, such as Trichoderma , Hypoxylon , Tritirachium , Paenibacillus , Bacillus , Haliangium and Streptomyces , increased compared to the OF treatment, whereas the soil-borne pathogen, Fusarium , was markedly decreased. Overall, the results of this study demonstrate that the application of the BIO was a useful and effective approach to suppress Fusarium wilt and that the high-throughput 454 pyrosequencing was a suitable method for the characterization of microbial communities of rhizosphere soil of cucumber.

AimsFor the sustainable development of agroecosystems in citrus orchards, we studied the short-term effects of bio-organic fertilizer substitution for chemical fertilizers on the dynamic changes in the soil environment.MethodsWe carried out a field experiment in citrus orchards. Five treatments were set up with a duration of six months and the substitution ratio was based on equivalent nitrogen substitution. Soil properties, soil labile organic carbon, and soil bacteria were measured and analyzed.ResultsBio-organic fertilizers substituting chemical fertilizers could significantly increase soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), dissolved organic carbon (DOC), and easily oxidized organic carbon (EOC) content (P < 0.05). The carbon pool management index (CPMI) was the largest in 75% bio-organic fertilizer treatment. In addition, the substitution of chemical fertilizers with bio-organic fertilizers significantly increased the alpha diversity of bacterial communities, with a maximum Shannon index of 9.78 for SF75. The relative abundance of Actinobacteria, Actinobacteria and Bacteroidetes was higher than that of CK, while the relative abundance of Acidobacteria and Choloflexi was lower than that of the control group. Redundancy analysis showed that DOC, CPMI, available potassium (AK), and nitrate-nitrogen (NO3−-N) were the main driving factors affecting the bacterial community structure. The highest expression abundance of metabolic pathways in soil bacteria was predicted by KEGG to exist.ConclusionWe conclude that the appropriate application of bio-organic fertilizer improved soil properties and reshaped bacterial ecology and 75% bio-organic fertilizer is a promising fertilization practice for citrus orchard soils.

Soil acidification in tea plantation seriously reduced the yield and quality of tea. It was an effective method to use organic fertilizer for acidified soil remediation to ensure tea yield and quality. In this study, different fertilizers were used to treat the acidified tea plantation soils for 4 consecutive years to analyze the remediation effect of different fertilizers on acidified soil and their effects on tea yield and quality. The results showed that during the period of 2017-2021, the soil pH value of tea plantation (S1) with long-term use of chemical fertilizer decreased continuously, from 3.07 to 2.82. In the tea plantation (S2), the soil pH value was stable between 4.26 and 4.65 in the combination of organic fertilizer and chemical fertilizer for a long time. The tea plantation (S3) with long-term use of organic fertilizer has a stable soil pH value between 5.13 and 5.33, which is most suitable for the growth of tea trees. The analysis results of tea yield and quality indicators (tea polyphenols, theanine, amino acids, caffeine, catechin components) showed that after long-term use of chemical fertilizer in S1 tea plantation, soil pH value decreased continuously, soil acidification intensified, tea tree growth was hindered, and tea yield and quality decreased continuously. S2 tea plantation used some organic fertilizer in combination with chemical fertilizer for a long time, the soil pH value gradually improved, soil acidification weakened, and tea yield and quality improved steadily. After long-term use of organic fertilizer in S3 tea plantation, soil acidification was significantly improved, which was conducive to the normal growth of tea trees and the yield and quality of tea reached the maximum. The results of interaction analysis showed that the long-term use of chemical fertilizer had a negative effect on the growth of tea trees, and the combination of organic fertilizer and chemical fertilizer improved the growth of tea trees to some extent, but the effect was poor, while the long-term use of organic fertilizer was the most beneficial to the growth of tea trees and most conducive to ensuring the yield and quality of tea. This study provides important practical significance for the remediation and fertilizer regulation of acidified tea plantation soils. In the process of field experiment, climate is a variable factor, and attention should be paid to the effect of climate change on fertilization efficiency in subsequent experiment.

AimsOrganic fertilizer addition plays a significant role for soil organic carbon (SOC) storage. The interaction between bacteria and clay minerals for the mechanism of SOC storage with organic fertilization was investigated in saline-alkaline paddy soil.MethodsA 9-year field experiment was arranged, which included: (a) CK, without fertilizer addition, (b) NPK, mineral N, P and K fertilizer addition, (c) NPKC1, and (d) NPKC2, mineral N, P and K fertilizer plus 450 and 900 kg C ha−1, respectively.ResultsIn comparison to only mineral fertilization, the content of humic acid-C and humin-C was significantly increased by 58.8%–70.6% and 46.9–53.1% with organic fertilizer addition, respectively. The 2:1 type clay minerals (vermiculite and illite) were also increased, which were positively correlated with SOC storage due to the formation of clay minerals-humus complexes. Meanwhile, the abundance of Geobacter and Anaeromyxobacter was increased with organic fertilization, which accelerated the transformation of clay minerals by promoting Fe reduction, and then increased SOC storage. While, compared with NPKC1 treatment, more Gammaproteobacteria and Anaerolineae, involved in the decomposition of SOC, were found in NPKC2 treatment. Relative to NPK treatment, SOC storage of NPKC1 and NPKC2 treatments increased by 23.3% and 29.8%, respectively, and there was no significant difference between the two treatments.ConclusionsTherefore, appropriate addition of organic fertilizer is a better fertilization practice to promote stability and storage of SOC, which provided an important contribution to elucidate the role of mineral-microbial interactions for storage of SOC in saline-alkaline paddy soil.

It’s been long known that the application of organic fertilizer (OF) and bio-organic fertilizer (BF) which containing beneficial microorganisms to pear trees can both significantly improve fruit quality and yield. In order to reveal the mechanism of BF and OF regulating fruit growth and quality in pear, the effects of BF and OF on the photosynthetic characteristics and the accumulation of major sugars and organic acids of the pear fruit were quantified compared with chemical fertilizer (CF). Additionally, the molecular mechanisms regulating pear fruit development and quality were studied through transcriptome analysis. The three treatments were conducted based on the same amounts of nitrogen supply. The results showed that compared with CF, BF and OF treatments increased the fruit yield, and also significantly improved the photosynthesis efficiency in pear. BF and OF both significantly increased the sucrose content but significantly decreased the fructose and glucose content within the pear fruit. The amount of malic acid was significantly higher in OF treatment. Compared with CF and OF, BF significantly increased the sugar-acid ratio and thus improved the fruit quality. Transcriptome analysis and weighted correlation network analysis (WGCNA) revealed that the sugar metabolism of fruits applied with the BF was enhanced compared with those applied with CF or OF. More specifically, the expression of SDH (Sorbitol dehydrogenase) was higher in BF, which converts sorbitol into fructose. For both of the OF and BF, the transcript abundance of sugar transporter genes was significantly increased, such as SOT (Sorbitol transporter) , SUT14 (Sugar transport 14) , UDP-GLUT4 (UDP-glucose transporter 4) , UDP-SUT (UDP-sugar transporter), SUC4 (Sucrose transport 4), SUT7 (Sugar transporter 7), SWEET10 and SWEET15 (Bidirectional sugar transporter) , which ensures sugar transportation. The genes involved in organic acid metabolism showed decreased transcripts abundance in both BF and OF treatments, such as VAP (Vesicle-associated protein) and cyACO (Cytosolic aconitase) , which reduce the conversion from succinate to citric acid, and decrease the conversion from citric acid to malic acid in the TCA cycle (Tricarboxylic Acid cycle) through Pept6 (Oligopeptide transporter). In conclusion, the application of BF and OF improved fruit quality by regulating the expression of sugar and organic acid metabolism-related genes and thus altering the sugar acid metabolism. Both BF and OF promote sucrose accumulation and citric acid degradation in fruits, which may be an important reason for improving pear fruit quality. The possible mechanism of bio-organic fertilizer to improve fruit quality was discussed.

Background and aims It has been confirmed that the declines in arbuscular mycorrhizal fungi (AMF) populations and agroecosystem diversity are largely due to nutrient enrichment caused by fertilization. Replacing chemical-only fertilization with organic fertilization is widely considered a possible approach for maintaining soil biodiversity and a healthy functioning ecosystem. Here we aim to examine the effects of organic fertilizer on AMF occurrence. Methods We conducted a meta-analysis of 162 field experiments from 54 published studies conducted over the last 20 years. Our dataset included two groups: organic fertilization (OF) vs chemical-only fertilization (CF) and OF vs no fertilization (NF). Results We found that organic fertilizer increased AM fungal biomass and was less detrimental to AMF richness than mineral-only fertilization. AMF responses to organic fertilizer were generally positive when AMF and host plants had a strong mutualistic symbiosis such as in phosphorus-deficient soil, drought and semi-drought areas, at low latitudes, and at testing sites that contained two or more plant species or included legume. In conditions other than these, the responses were generally negative. Organic carbon input, increased soil phosphorus and the ratio of fertilizer N and P jointly explain the effects of organic fertilizer on AMF occurrence. Conclusions Our analysis indicates that, although some limiting factors exist, application of organic fertilizer can be an effective practice to protect AM symbiosis from the negative effects of nutrient enrichment in current cropping systems.