The mechanisms of microbial and soil carbon pool responses to soil aggregates improvement by different organic fertilizers.

<p>Soil aggregation is a key element of soil structure, providing a range of micro-niches for soil-borne microorganisms and creating fine-scale heterogeneity in physical and chemical properties. Soil microorganisms drive a range of critical terrestrial ecosystem functions. The importance of understanding the impact of soil aggregates on microbiome assembly and function is increasingly becoming appreciated. In this study, we used a long-term tomato monoculture field as a model system to investigate the impact of soil aggregates on bacterial community assembly and inhibition of the pathogen <em>Ralstonia solanacearum</em>. Samples were collected after harvest from experimental fields with either no fertilizer (CK), chemical fertilizer (CF), organic fertilizer (BF) or a bio-organic fertilizer (BF) and separated into categories of soil aggregates (e.g. <0.25 mm, 0.25-1 mm, 1-2 mm, >2 mm) by a wet-sieving method. Bacterial community composition was found to differ significantly across aggregate fractions, and bacterial communities from larger aggregate fractions exhibited a higher degree of phylogenetic clustering. Furthermore, we found that soil aggregate size classes differed in the relative importance of deterministic versus stochastic processes Fields with different fertilization differ in soil aggregates distribution and disease suppression. Fields with organic inputs (OF, BF) had a higher abundance of large macro-aggregates and fewer micro-aggregates than inorganic input treatments (CK, CF). Meanwhile, disease incidences were lowest in BF, then increasing in OF, CF and CK, orderly. Interestingly, only relative density of <em>R. solanacearum</em> in micro-aggregates was positively correlated with disease. Furthermore, in experiments involving inoculation of <em>R. solanacearum </em>into aggregate size fractions recovered from field samples, only micro-aggregates (<0.25 mm) from the low disease incidence soil (BF) showed significantly higher resistance against pathogen invasion as compared to the high disease incidence soil (CF). In summary, under agricultural practice, soil aggregates can mediate the ecological assembly processes of bacterial communities, thereby influences the suppression of bacterial wilt disease. Soil structure and aggregation should therefore be considered in strategies to improve soil-borne resistance to plant pathogens.</p>

As an important grain production area in China, the Northeast Black Soil Region has experienced many problems, such as soil degradation, fertility decline, and grain yield reduction, in recent years. Optimizing fertilizer management is an important measure to maintain and enhance soil fertility. However, improper fertilizer application could aggravate nutrient losses and greenhouse gas N2O emissions, thus leading to soil degradation and environmental pollution. The objectives of the present study were to investigate the response of N2O emission from black soil to long-term application of organic and chemical fertilizers and the key controlling factors. Soil samples （0-20 cm） were collected from a total of nine treatments, including organic fertilizer as the primary treatment （M0- no organic fertilizer； M1- low organic fertilizer； M2- high organic fertilizer） and chemical fertilizer as the secondary treatment （CK- no fertilizer； N- chemical nitrogen fertilizer； NPK- chemical nitrogen, phosphorus, and potassium fertilizer）, in a long-term experiment （32 years） on the black soil of Gongzhuling, Jilin Province. The soil samples were incubated at 25℃ with 65% field water holding capacity for 21 days, and N2O emission and soil physico-chemical biological properties were determined. The results showed that long-term application of organic and chemical fertilizers notably increased N2O emissions from black soil. Compared to those from the M0CK treatment [（0.25±0.01） mg·kg-1, in terms of N, the same as below], the cumulative N2O emissions from the only organic fertilizer treatment significantly increased by 361%-456% [（1.17±0.02） mg·kg-1 and （1.41±0.02） mg·kg-1 for the M1CK and M2CK treatments, respectively]. Furthermore, the N2O emissions strongly increased with increasing organic fertilizer application amounts. Cumulative N2O emissions were significantly higher in the chemical fertilizer treatments by 96%-236% [（0.49±0.01） mg·kg-1 and （0.84±0.03） mg·kg-1 for the M0N and M0NPK treatments, respectively] compared to those in the M0CK treatments. Moreover, the increased N2O emissions due to fertilizers application were significantly larger in the M0NPK relative to M0N treatments. The positive effects of chemical fertilizer application on N2O emission decreased under organic fertilizer amendments （M1 and M2）, indicating that organic fertilizer application alleviated increased N2O emission because of chemical fertilization. The application of organic fertilizers significantly increased bulk soil, aggregate organic carbon （SOC）, total nitrogen （TN）, and soil microbial carbon and nitrogen contents. The application of organic combined with chemical fertilizers further increased SOC and TN contents in bulk soil and aggregates. Pearson correlation and path model analyses showed that the N2O emission was positively correlated with soil carbon and nitrogen fractions and microbial carbon and nitrogen contents among organic and chemical fertilizer treatments. Long-term application of organic and chemical fertilizers strongly regulated N2O emissions via affecting the distribution of carbon and nitrogen contents in soil fractions and changing microbial biomass and substrate availability. In conclusion, the application of organic fertilizers could significantly facilitate N2O emission by increasing the available soil carbon and nitrogen pools as well as microbial carbon and nitrogen contents. The application of organic fertilizers mitigated the positive effects of chemical fertilizers on N2O emissions. Appropriate amounts of organic fertilizers should be used when applying chemical fertilizers, in order to balance the comprehensive effects of fertility improvement with nitrogen loss and greenhouse gas emissions.

Long-term use of chemical fertilizers (CFs) can cause soil compaction and acidification. In recent years, bio-organic fertilizers (BOFs) have begun to replace CFs in some vegetables and cash crops, but the application of CFs or BOFs has resulted in crop quality and disease occurrence. This study aimed to analyze the microbial mechanism of differences between CFs and BOFs in root disease, quality, and yield of tuber Chinese herbal medicine. We studied the effects of CFs, organic fertilizers, commercial BOFs, biocontrol bacteria BOFs, and biocontrol fungi BOFs on rhizosphere microbial community structure and function, root rot, quality, and yield of Codonopsis pilosula at different periods after application and analyzed the correlation. Compared to CFs, the emergence rate and yield in BOF treatments were increased by 21.12 and 33.65%, respectively, and the ash content, water content, and disease index in the BOF treatments were decreased by 17.87, 8.19, and 76.60%, respectively. The structural equation model showed that CFs promoted the quality and yield of C. pilosula by influencing soil environmental factors, while BOFs directly drove soil bacterial community to reduce disease index and improve the quality and yield of C. pilosula. There was a stronger interaction and stability of soil microbial networks after BOF treatments. Microlunatus, Rubrobacter, Luteitalea, Nakamurella, and Pedomicrobium were identified as effector bacteria, which were related to disease prevention and yield and quality increase of C. pilosula. Microbial functional analysis indicated that the signal transduction and amino acid metabolism of soil bacteria might play a major role in improving the quality and yield of C. pilosula in the early and middle growth stages. In conclusion, compared to CFs, BOFs obtained a lower disease index of root rot and a higher quality and yield of C. pilosula by changing the structure and function of the rhizosphere bacterial community.

تأثیر منابع نیتروژن و فسفر بر خصوصیات شیمیایی خاک و غلظت عناصر در آفتابگردان(Helianthus annuus L.)

This study explored the effect of the combined application of chemical and organic fertilizers on phosphorus morphology and its conversion to an active state. A long-term field positioning experiment comprising five treatments was conducted in black soil. The results concluded that the soil total phosphorus (TP), available phosphorus (AP), inorganic phosphorus, and organic phosphorus contents of all treatments ranked as follows: 1.5M1NPK > M2NPK > M1NPK > NPK > CK. The long-term application of chemical and organic fertilizers increased the proportion of soil reactive phosphorus and moderately reactive phosphorus but decreased the proportion of mildly active phosphorus and residual phosphorus. A phosphorus-31 nuclear magnetic resonance (31P NMR) spectral analysis showed that the contents of orthophosphate, pyrophosphate, phosphoric acid diesters, and orthophosphate acid monoesters increased with the application of chemical and organic fertilizers, of which 1.5M1NPK usually resulted in the highest increases. In conclusion, the long-term application of chemical fertilizers could promote the conversion of soil phosphorus into active phosphorus and improve the effectiveness of soil phosphorus, and the long-term use of organic and chemical fertilizers was more effective than the use of chemical fertilizers only, with 1.5M1NPK providing the best effects.

Soybean cropping patterns affect trait-based microbial strategies by changing soil properties

Different regulation of soil structure and resource chemistry under animal- and plant-derived organic fertilizers changed soil bacterial communities

The extensive use of chemical fertilizers poses serious collateral problems such as environmental pollution, pest resistance development and food safety decline. Researches focused on applying plant-beneficial microorganisms to partially replace chemical fertilizer use is increasing due to the requirement of sustainable agriculture development. Thus to investigate the possibility of a plant-beneficial Trichoderma strain and its bio-organic fertilizer product in saving chemical fertilizer application and in improving crop quality, a field trial and continuous pot experiments were carried out with tomato. Four treatments were set up: a reduced application of chemical fertilizer (75% of the conventional application) plus Trichoderma-enriched bio-organic fertilizer (BF), organic fertilizer (OF) or Trichoderma spore suspension (SS), with using the 100% rate of the conventional chemical fertilizer as the control (CF). The results showed that the total soluble sugar, Vitamin C and nitrate accumulations were, respectively, +up to 24%, +up to 57% and –up to 62% in the tomatoes of the BF treatment compared to those of the control (CF). And both of the pot and field trials revealed that reduced rates of chemical fertilizer plus bio-organic fertilizer produced tomato yields equivalent to those obtained using the 100% of the chemical fertilizer. However, application with the inoculant alone (SS) or combined with the organic fertilizer alone (OF) would lead to a yield decreases of 6–38% and 9–35% over the control. Since the increased abundance of soil microflora and the enhanced soil fertility frequently showed positive linear correlations especially in the BF-treated soils, we conclude that the efficacy of this bio-organic fertilizer for maintaining a stable tomato yield and improving tomato quality may be due to the improved soil microbial activity. Thus, the results suggest that the Trichoderma bio-organic fertilizer could be employed in combination with the appropriate rates of chemical fertilizers to get maximum benefits regarding yield, quality and fertilizer savings.

Presently, Compost and compost tea with additional chemical fertilizers increase the organic carbon and soluble salts of soil, finally enhance the productivity of Egyptian hybrid rice one (H1). A field experiment was conducted in two successive seasons 2015 and 2016 at the experimental farm of Rice Research and Training Center (RRTC), Sakha, Kafrelsheikh, Egypt; to evaluate the influence of different chemical fertilizers (NPK) levels with combined compost and compost tea on yield, yield attributes, chemical compositions and quality of grains of Egyptian hybrid rice one. A randomized Complete Block Design with four replications was used. The results indicated that there were significant positive effects of chemical NPK fertilizers with compost and compost tea on number of panicles m-2 at harvest, filled grain percentage, 1000-grain weight, N uptake in grain and straw, phosphorus and potassium content as well as grain quality. Combination of chemical fertilizers with compost and compost tea were gave the maximum crop yield as well as all the previous characters higher than for the single application of organic or chemical fertilizer alone. Thus, it concluded that the applying N110P24K40 + compost as organic fertilizer + compost tea as bio-organic fertilizer could be used successfully to enhance the productivity of Egyptian hybrid rice one, without any significantly differences with N165P36K60 as recommended NPK doses. Integrated use of chemical NPK fertilizer with compost or compost tea positively affected the yield attributes and yield of hybrid rice and contributed in reducing chemical NPK fertilizers by 1/3 as well as minimizing the cost of inputs and environmental pollution.

Soil microorganisms have an important influence on the transformation of soil nutrients. As functional genes encoding phosphatase, phoC and phoD provide effective means for detecting the types, abundance, and community structure of microorganisms in the environment, and studying the changes in the diversity of phoC and phoD gene microbial communities in the rhizosphere and non-rhizosphere soil of the plant rhizosphere and non-rhizosphere soil under the treatment of chemical fertilizer and organic fertilizer combined with biochar can provide a scientific basis for the agricultural utilization of biochar. In this study, corn stalks and rice husk stalks were used as test materials, and the pot experiment method was used to set the following treatments:control (CK), traditional fertilization (F), chemical fertilizer+20 t·hm-2 rice husk biochar (FP), chemical fertilizer+10 t·hm-2 rice husk biochar+10 t·hm-2 corn biochar (FPM), organic fertilizer+20 t·hm-2 rice husk biochar (PP), and fresh organic fertilizer+20 t·hm-2 rice husk biochar (NPP). The community structure of phoC and phoD genes in rhizosphere and non-rhizosphere soil was analyzed by using T-RFLP and fluorescence quantitative PCR technology to clarify the response characteristics of phoC and phoD genes to the addition of biochar. The results showed that:① In rhizosphere soil and non-rhizosphere soil, the phoD gene community structure was more complicated than that of phoC, and the number of end restriction fragments of the phoC gene increased after chemical fertilizer and organic fertilizer were combined with biochar. ② The combined application of biochar with chemical fertilizer and organic fertilizer reduced the copy number of the phoC gene in non-rhizosphere soil compared with that in the CK. Compared with that in the CK, the copy number in the FP, FPM, PP, and NPP treatments decreased by 9.18%, 11.46%, 10.97%, and 13.76%, respectively. Organic fertilizer combined with biochar increased the copy number of the phoD gene in rhizosphere soil by 2.48% and 5.16% in the PP and NPP treatments, respectively, compared with that in the CK. ③ Total phosphorus in the soil was the main factor affecting the phoC gene microbial community structure in non-rhizosphere soil (P<0.01), whereas the phoC gene microbial community structure in rhizosphere soil was regulated by a variety of environmental factors. pH was the most critical factor affecting the phoD gene copy number, and the copy number of phoD gene was significantly correlated with soil nitrate nitrogen and pH. The combined application of biochar with chemical fertilizers and organic fertilizers can promote the growth and reproduction of microorganisms that function in soil phosphorus conversion, which is of great significance for improving the utilization of phosphorus fertilizers.

به منظور بررسی اثرات کود‌‌های آلی و شیمیایی بر برخی ویژگی‌های کمی و کیفی چای ترش آزمایشی در قالب طرح بلوک‌های کامل تصادفی با 10 تیمار و 4 تکرار در مزرعه تحقیقاتی دانشکده کشاورزی دانشگاه زابل انجام شد. تیمار‌ها شامل: (T1) عدم مصرف کود (شاهد)، (T2) 300 کیلوگرم کود نیتروژن، فسفر و پتاسیم در هکتار به نسبت 2:1:1، (T3) 20 تن کود گاوی در هکتار، (T4) 10 تن کمپوست در هکتار، (T5) 5 تن ورمی‌کمپوست در هکتار، (T6) محلول پاشی اسید هیومیک به نسبت 5/1 در هزار، (T7) 50 درصد T2 + T6، (T8) 50 درصد T3 + T6، (T9) 50 درصد T4 +T6 و (T10) 50 درصد T5 + T6 بودند. نتایج نشان داد در اکثر صفات مورد بررسی اختلاف معنی‌داری بین تیمارهای اعمال شده و شاهد وجود داشت، به طوری که بیشترین مقدار ارتفاع و تعداد شاخه‌های جانبی و قطر ساقه در نتیجه کاربرد تیمار کودهای آلی توأم با اسید هیومیک (T8، T9 و T10) حاصل شد. تأثیر کود‌ کمپوست توأم با اسید هیومیک (T9) بر وزن‌تر و خشک کاسبرگ (31/157، 69/22 گرم در بوته)، تعداد میوه در بوته، وزن میوه، تعداد دانه در بوته، و در مورد میزان آنتوسیانین، تأثیر کود گاوی توأم با اسید هیومیک (T8) نسبت به سایر تیمارها بیشتر بود. نتایج این تحقیق نشان داد که کاربرد کودهای آلی در بهبود عملکرد کمی و کیفی گیاه دارویی چای ترش و همچنین در جهت پایداری تولید و حفظ محیط زیست تأثیر مثبتی داشته و به نظر می‌رسد کودهای آلی جایگزین مناسبی برای کودهای شیمیایی باشند.

به منظور بررسی تاثیر کاربرد کودهای آلی، معدنی و زیستی بر عملکرد و اجزای عملکرد دانه گیاه کاسنی پاکوتاه آزمایشی در سال زراعی 91-1390، به صورت فاکتوریل و در قالب طرح بلوک‌های کامل تصادفی با چهار تکرار در مزرعه تحقیقاتی دانشکده کشاورزی دانشگاه فردوسی مشهد انجام گرفت .در این آزمایش فاکتور کودهای آلی و شیمیایی در چهار سطح (چهار تن در هکتار کمپوست زباله شهری، چهار تن در هکتار ورمی‌کمپوست،130 کیلوگرم در هکتار کود اوره و عدم مصرف کود (شاهد)) و فاکتورکود زیستی در دو سطح (کود زیستی بیوسولفور + 100 کیلوگرم در هکتار کود گوگرد خالص و عدم مصرف کود زیستی بیوسولفور و گوگرد (شاهد)) استفاده شد. نتایج نشان داد اثرات ساده و متقابل فاکتورهای مورد مطالعه، روی صفات مورفولوژیک (ارتفاع بوته، تعداد پنجه در بوته، تعداد شاخه‌های فرعی در بوته)، اجزای عملکرد دانه مانند، تعداد دانه در گل‌آذین، وزن هزار دانه، وزن دانه در بوته، عملکرد دانه و شاخص برداشت معنی‌دار نبود. نتایج جدول تجزیه واریانس نشان داد که تعداد گل‌آذین در بوته، تعداد دانه در بوته و عملکرد بیولوژیک (05/0 p

Overuse of chemical fertilizer has led to severe land degradation and environmental pollution in China. Switching to organic fertilizer may improve soil quality and reduce pollution, which is meaningful to the sustainable development of Chinese agriculture. This study examines how farmers’ perceptions and risk preference affect their organic fertilizer investment using a representative rural household survey from Guangxi, a major agricultural region in China. Tobit and double-hurdle models are used to empirically test their impacts on organic fertilizer adoption and investment. An ordinary least squares model is used to regress chemical fertilizer use on the same set of explanatory variables to compare and contrast farmers’ different fertilizer investment behaviors. It is found that both organic fertilizer perceptions and risk attitude significantly affect organic fertilizer investment. Perceived yield-increasing and quality-improving effects encourage organic fertilizer investment, while perceived cost increases discourage it. Moreover, risk-averse farmers are more likely to invest in organic fertilizers. Most of the perceptions affecting organic fertilizer investment have an opposite impact on chemical fertilizer investment, which suggests substitutability between organic and chemical fertilizer. Interventions that aim to improve farmers’ perceptions of organic fertilizer and illustrate its risk-reduction effect could be effective in promoting organic fertilizer use, which can help achieve China’s sustainable development of agriculture.

The rate of chemical fertilizers’ utilization by crops does not exceed 40%. Environmental pollution and resource waste caused by the excessive application of chemical fertilizers have led to increased interested in using organic fertilizers as replacements for chemical ones. The present study investigated the impact of the combined application of chemical and organic fertilizers on the growth and nutrient utilization efficiency of highland barley (Hordeum vulgare L.). Compared to the application of 100% chemical fertilizers (OFR0), the substitution of chemical fertilizer with 40% organic fertilizer (OFR40) resulted in a significant increase in root length by 4% and improved the nutrient absorption capacity. The crop yields at harvest were not diminished in the combined fertilizer group compared to the OFR0 treatment group, while simultaneously achieving a 60% reduction in chemical fertilizer application. However, a complete substitution with 100% organic fertilizer (OFR100) resulted in a lower yield. This suggests that appropriate proportions of organic fertilizer replacement can maintain yield by increasing root length and enhancing the crop’s nutrient absorption capacity. In order to elucidate the mechanisms by which organic fertilizer modulates crop growth and nutrient utilization efficiency, combined transcriptomic and metabolomic analysis revealed that as the concentration of organic fertilizer increased, the differentially expressed genes (DEGs) and differentially accumulated metabolites (DAMs) shifted from secondary metabolite synthesis toward nitrogen metabolism. In addition, the gene expression and enzymatic activity of NR (nitrate reductase), GS (glutamine synthetase), and GOGAT (glutamine oxoglutarate aminotransferase) (key genes in the nitrogen metabolism pathways) were significantly enhanced in the OFR40 group. This study’s omics-based approach demonstrates that the combined use of chemical and organic fertilizers enhances nitrogen absorption and utilization through an increased expression of key genes and enzymatic activities within the nitrogen metabolic pathways. This synergistic effect not only maintains crop yields but also reduces the reliance on chemical fertilizers, offering a sustainable strategy for agricultural production.

Impacts of long-term chemical and organic fertilization on soil puddlability in subtropical China