Substitution Of Chemical Fertilizer Research Articles

Organic fertilizer substitution benefits microbial richness and wheat yield under warming

Climate warming poses a serious threat to soil biodiversity and crop yield. Application of organic fertilizer has been extensively practiced to improve soil health and crop productivity. However, information is limited about the effects of organic fertilizer on microbial communities and diversity (richness) under warming. Thus, to investigate the interactive effects of temperature (ambient temperature and warming) and fertilizer (chemical fertilizer and partial substitution of chemical fertilizer with organic fertilizer) on microbial properties and wheat yield, a two-factorial pot experiment was conducted using soils with high and low fertility The results showed that warming and organic fertilizer had minor effects on bacterial Shannon and Simpson indexes. Due to concomitant reductions in soil moisture, warming decreased the average Chao index by 5.4 % and Ace index by 3.8 % for soils with high and low fertility (P < 0.05). High-throughput sequence presented that dominated genus was Bacillus with spore-forming ability. Under warming and drying conditions, microbes with adaptive traits (spore-forming ability) would outcompete the other microbes, and decrease microbial Chao and Ace index (richness). However, organic fertilizer counteracted the adverse effects of warming on microbial richness attributed to positive interaction between temperature and fertilizer on soil nutrients and organic carbon. The strong relationships between bacterial richness and wheat yield, as well as soil nutrients, highlighted the importance of soil biodiversity in improving soil nutrients and crop productivity. Partial substitution of chemical fertilizer with organic fertilizer significantly increased wheat yield by 27.1 % and 14.9 % under ambient temperature and by 28.0 % and 19.6 % under warming for soils with high and low fertility, respectively. Overall, this study provided the possibility to increase bacterial richness related to nutrient turnover and crop production by organic fertilizer application with reduced chemical fertilizer, especially under climate warming.

Synergistic Effects of Soil-Based Irrigation and Manure Substitution for Partial Chemical Fertilizer on Potato Productivity and Profitability in Semiarid Northern China.

Soil-based irrigation and the partial substitution of chemical fertilizers with manure are promising practices to improve water and nitrogen (N) use efficiency. We hypothesize that their combination would simultaneously benefit potato production, tuber quality and profitability. A two-year experiment was conducted in semiarid northern China to investigate the combined effects of three water treatments [rainfed (W0), soil-based irrigation (W1), conventional irrigation (W2)] and three N treatments [no N (N0), chemical N (N1), 25% manure substitution (N2)] on these indicators, and to perform a comprehensive evaluation and correlation analysis. The results showed that water and N treatments separately affected all indicators except vitamin C content. Compared to W2, W1 significantly increased water productivity by 12% and irrigation water use efficiency (IWUE) by 30% due to 10% lower evapotranspiration and 21% lower water use. However, W1 and W2 negatively affected crude protein content. Conversely, this was compensated by the combination with N1 and N2. There were slight differences between N1 and N2 for all indicators on average across water treatments, while under W1, N2 significantly increased leaf area index (LAI) and N recovery efficiency (REN) by 18% and 29.4%, respectively, over N1. Also, comprehensive evaluations showed that W1N2 performed best, with the highest tuber yield, profit and acceptable quality. This can be explained by the increase in LAI, IWUE and REN due to the positive correlations with tuber yield and net return. Consequently, soil-based irrigation combined with 25% manure substitution had complementary effects on tuber quality and synergistic effects on potato productivity and profitability.

Continuous Biogas Slurry Substitution of Chemical Fertilizer with Wheat/Maize Straw Return Alters Surface and Subsoil Physicochemical and Aggregate Properties Differently

Continuous Biogas Slurry Substitution of Chemical Fertilizer with Wheat/Maize Straw Return Alters Surface and Subsoil Physicochemical and Aggregate Properties Differently

Optimization of nutrient management improves productivity, quality and sustainability of albino tea cultivar Baiye-1.

Proper nutrient management is crucially important to the sustainable development of tea production. Compared to normal green-leaf cultivars, albino tea cultivars produce green tea of superior quality characterized by high contents of amino acids as a result of the hydrolysis of chloroplast proteins at albinism. However, the advantage of albino tea cultivars was offset by inferior growth and yield performance because of low contents of chlorophylls and limited photosynthesis capacity. Our understanding about the nutrition characteristics of albino tea cultivars was very limited. A four-year field experiment was conducted to develop proper nutrient management for Baiye-1 to overcome its weakness of low productivity without a tradeoff in tea quality and environmental risks. The nutrient management schemes were formulated by optimizing the rate and ratio of nitrogen (N), phosphorus, potassium and magnesium together with substitution of chemical fertilizers with organic manures. The total amounts of nutrients in the optimized schemes were reduced by 25% compared to the local farmers' practice (FP). Results showed that optimized rates and ratio of nutrients together with partial substitution of chemical fertilizers with rapeseed cake manure more considerably improved albino tea yield, the contents of free amino acids, total polyphenol and catechins relative to FP. Partial substitution of chemical fertilizers with commercial livestock manure decreased tea quality, which was likely caused by a dilution effect of increasing tea yield and decreasing N status of tea plants. Full organic substitution of chemical fertilizers by rapeseed cake manure improved tea yield and quality but had relatively low agronomic efficiency and profit. The effect of optimized nutrient management schemes was associated with the improvement of nutritional status in tea plants. The present work demonstrated that the optimization of nutrient management considerably improved albino tea yield, quality and profit while decreased the application rate of fertilizers and the intensity of greenhouse gas emissions.

Partial substitution of chemical fertilizer by organic fertilizer increases yield, quality and nitrogen utilization of Dioscorea polystachya.

This field experiment aimed to investigate the effects of different ratios of organic and inorganic fertilizers with maintaining equal nitrogen application rates on the yield, quality, and nitrogen uptake efficiency of Dioscorea polystachya (yam). Six treatments were set, including a control without fertilizer (CK), sole application of chemical fertilizer (CF), sole application of organic fertilizer (OM), 25% organic fertilizer + 75% chemical fertilizer (25%OM + 75%CF), 50% organic fertilizer + 50% chemical fertilizer (50%OM + 50%CF), and 75% organic fertilizer + 25% chemical fertilizer (75%OM + 25%CF). The experiment followed a randomized complete block design with three replications. Various yield parameters, morphology, quality indicators, and nitrogen utilization were analyzed to assess the differences among treatments. The results indicated that all fertilizer treatments significantly increased the yield, morphology, quality indicators, and nitrogen utilization efficiency compared to the control. Specifically, 25%OM + 75%CF achieved the highest yield of 31.96 t hm-2, which was not significantly different from CF (30.18 t hm-2). 25%OM + 75%CF exhibited the highest values at 69.23 cm in tuber length and 75.86% in commodity rate, 3.14% and 1.57% higher than CF respectively. Tuber thickness and fresh weight of 25%OM + 75%CF showed no significant differences from CF, while OM and 50%OM+50%CF exhibited varying degrees of reduction compared to CF. Applying fertilizer significantly enhanced total sugar, starch, crude protein, total amino acid, and ash contents of D. polystachya (except ash content between CK and OM). Applying organic fertilizer increased the total sugar, starch, crude protein, total amino acid, and ash contents in varying degrees when compared with CF. The treatment with 25%OM+75%CF exhibited the highest increases of 6.31%, 3.78%, 18.40%, 29.70%, and 10%, respectively. Nitrogen content in different plant parts followed the sequence of tuber > leaves > stems > aerial stem, with the highest nitrogen accumulation observed in 25%OM + 75%CF treatment. Nitrogen harvest index did not show significant differences among treatments, fluctuating between 0.69 and 0.74. The nitrogen apparent utilization efficiency was highest in 25%OM + 75%CF (9.89%), followed by CF (9.09%), both significantly higher than OM (5.32%) and 50%OM + 50%CF (6.69%). The nitrogen agronomic efficiency varied significantly among treatments, with 25%OM + 75%CF (33.93 kg kg-1) being the highest, followed by CF (29.68 kg kg-1), 50%OM + 50%CF (21.82 kg kg-1), and OM (11.85 kg kg-1). Nitrogen partial factor productivity was highest in 25%OM + 75%CF treatment (76.37 kg kg-1), followed by CF (72.11 kg kg-1), both significantly higher than 50%OM + 50%CF (64.25 kg kg-1) and OM (54.29 kg kg-1), with OM exhibiting significantly lower values compared to other treatments. In conclusion, the combined application of organic and inorganic fertilizers can effectively enhance the yield, quality, and nitrogen utilization efficiency of D. polystachya. Particularly, the treatment with 25% organic fertilizer and 75% chemical fertilizer showed the most promising results.

Substituting Partial Chemical Fertilizers with Bio-Organic Fertilizers to Reduce Greenhouse Gas Emissions in Water-Saving Irrigated Rice Fields

Conventional water and fertilizer management practices have led to elevated greenhouse gas emissions from rice fields and decreased the efficiency of water and fertilizer utilization in agricultural land. The implementation of water-saving irrigation and the substitution of chemical fertilizers with organic alternatives can influence CH4 and N2O emissions in rice fields. However, it remains unclear how the simultaneous application of both methods will affect the CH4 and N2O emissions in rice fields. Therefore, two irrigation methods (F: flooded irrigation; C: controlled irrigation) and three fertilization modes (A: full chemical fertilizer; B: bio-organic fertilizer replacing 15% chemical nitrogen fertilizer; C: bio-organic fertilizer replacing 30% chemical nitrogen fertilizer) were set up through field experiments to explore the effect of greenhouse gas emission reduction in rice fields by combining controlled irrigation and bio-organic fertilizers. Substituting some chemical fertilizers with bio-organic fertilizers can lower the peak CH4 and N2O fluxes in rice fields, leading to a decrease in the cumulative CH4 and N2O emissions by 11.9~29.7% and 10.8~57.3%, respectively. The reductions led to a considerable decrease in the global warming potential (GWP) and the greenhouse gas emission intensity (GHGI) by 16.1~48.1% and 16.3~48.1%, respectively. Controlled irrigation significantly reduced CH4 emissions by 55.2~69.4% compared with flooded irrigation in rice fields. However, it also increased N2O emissions by 47.5~207.9%, considerably reducing their GWPs by 11.8~45.5%. Neither bio-organic fertilizer substitution nor controlled irrigation significantly affected rice yield. Replacing 15% of chemical nitrogen fertilizers with bio-organic fertilizers in controlled irrigation rice fields can minimize rice GWP and GHGI. The study’s results are of significant importance for enhancing the regulation of greenhouse gases in farmland and achieving sustainable agriculture through cleaner production.

Partial substitution of chemical fertilizer by green manure increases succeeding maize yield and annual economic benefit in low‐yield cropland in the Yellow River Delta

AbstractGreen manures (GM) combined with fertilizer reduction is an efficient measure to alleviate the environmental issues caused by the overapplication of chemical fertilizer. However, both the environmental and economic benefits remain unclear in coastal regions that are affected by both soil salinization and climate change. A field experiment was conducted in low‐yield cropland in the Yellow River Delta to explore the effects of green manure rotation combined with fertilizer reduction on the soil environment and economic sustainability. Two GM species, Vicia villosa (HV) and Orychophragmus violaceus (OV), a traditional winter wheat (Wheat), were grown in winter, with a fallow control (Fallow). In the subsequent maize season, three fertilizer rate treatments, a full rate of 600 kg ha−1 compound fertilizer (F100), 85% of the full rate (F85), and 70% of the full rate (F70), were applied in each former treatment. The results indicated that GM return markedly increased soil total N (TN) and P (TP) before the V6 stage of maize (when maize had 6 leaves). The average TN contents of HV and OV increased by 56.9% and 38.5%, respectively, compared with that of Wheat, while the values for TP were 13.6% and 16.9%. Compared with Fallow, the maize yields of HV and OV increased by 25.6% and 13.8%, respectively, while that of Wheat decreased by 9.1%. The average partial fertilizer productivities (PFPs) for HV and OV increased by 25.3% and 14.0% compared with Fallow, while Wheat decreased by 8.9%. The PFPs for F85 and F70 increased by 19.4% and 37.7%, respectively, compared with F100. Reducing the fertilizer rate to 70% in the HV–maize rotation pattern did not reduce but increased the total net profit and rate of return. Thus, HV–maize rotation combined with 30% fertilizer reduction is suggested for sustainable agriculture in this region.

Anaerobic digestates from cow dung and food waste as fertilizers: Effect on tomato growth and yield

Organic farming systems aim to reduce chemical inputs including fertilizers and ensure sustainable and eco-friendly production while recycling local renewable resources such as organic wastes. The aim of this study is to investigate the effect of two anaerobic digestates on tomato yield and growth in open field conditions. Digestates consisting of cattle dung and food waste from a 15 m3 demountable digester and fixed-dome digester, respectively, were applied to tomato cultivation using tree fertilization treatments: 1) raw (PD100) and 2) diluted up to 50% (PD50) cattle dung digestate, 3) food waste digestate (DD), and an unfertilized treatment (control) for 21 weeks. The results showed that tomato plants fertilized with PD50 and DD were significantly higher (+34% and +33%, respectively) compared to the control and PD100 (p&lt;0.05), and all digestate treatments significantly (p&lt;0.05) enhanced plant elongation compared to the control. This study suggests that anaerobic digestates can be a helpful alternative in the perspective of partial substitution of chemical fertilizers for sustainable tomato production.

Variations in crop yield caused by different ratios of organic substitution are closely related to microbial ecological clusters in a fluvo-aquic soil

ContextPartial substitution of chemical fertilizer with organic fertilizer (PSCFOF) can improve soil quality and reduce the overreliance of crop yield on chemical fertilizers. However, the relationship between alterations in crop yield and soil microbial community in response to various substitution ratios is not comprehensively understood. ObjectivesThis study aimed to investigate the impact of PSCFOF on soil nutrient supply, enzyme activity, bacterial and fungal community, and crop yield. MethodsAn 11-year (2009 – 2021) field experiment was carried out in a winter wheat–summer maize double-cropping system with four fertilization regimes (no fertilizer, NF; pure chemical fertilizer, NPK; 30% organic substitution, NPKLM; and 50% organic substitution, NPKHM). Co-occurrence network analysis was applied to examine the importance of ecological clusters and keystone species in controlling microbial activities and crop yields. ResultsThere were no significant differences in soil nutrient contents and annual crop yield between the NPK and NPKLM treatments. However, the NPKHM treatment resulted in significant reductions in crop yield by 9.49%− 16.78%, despite increasing soil organic matter (SOM), total nitrogen (TN), available nitrogen (AN), and available phosphorus (AP) by 9.05%, 7.26%, 11.67%, and 26.62%, respectively. This contrasting effect was primarily attributed to the influence of a specific ecological cluster (module 2), rather than the entire microbial community. Long-term 50% organic substitution would suppress keystone species within module 2, such as Aggregatilinea, Luteimonas, Usitatibacter and Microvirga. These species were specifically correlated with soil carbon enzyme activities, including β-glucosidase, invertase, and dehydrogenase, and contributed significantly and positively to crop yield. ConclusionsOrganic substitution at different ratios altered soil nutrient content, enzyme activities and microbial community in different intensities and directions. Long-term 30% organic substitution could preserve soil fertility and microbial community, leading to stable crop yield; whereas 50% organic substitution could inhibit keystone species, reduce extracellular enzyme activity and ultimately lead to a decrease in crop yield. ImplicationsOur results highlight the importance of ecological clusters within soil microbial co-occurrence network in regulating crop yield, presenting a new perspective on the variations in crop yield resulting from varying ratios of organic substitution.

Substitution of Chemical Fertilizer with Organic Fertilizer Can Affect Soil Labile Organic Carbon Fractions and Garlic Yield by Mediating Soil Aggregate-Associated Organic Carbon

This study aimed to explore the impact paths on soil organic carbon and crop yield of completely or partially substituting chemical N fertilizer with organic fertilizers. A four-year field experiment was conducted and included four treatments: (i) N0, no N fertilization application; (ii) NF, only synthetic N fertilizer application; (iii) 1/2OF, organic fertilizer substituted for 100% of the synthetic N fertilizer, with the total N application amount being equivalent to half that of NF; and (iv) 1/3OF + 2/3NF, organic fertilizer substituted for 1/3 of the synthetic N fertilizer with the total N application amount from organic and synthetic fertilizer being equivalent to that of NF. Soil total organic carbon (TOC), labile organic-carbon fractions (microbial biomass carbon (MBC), dissolved organic carbon (DOC), particulate organic carbon (POC), and easily oxidized organic carbon (EOC)), the carbon pool management index (CPMI), soil aggregated distribution, and water-stable aggregate-associated organic carbon were determined. Structural equation modeling (SEM) was used to clarify the impact paths of TOC and garlic yield changes under different N fertilizer treatments. Results showed that compared with N0 and NF, 1/2OF and 1/3OF + 2/3NF significantly increased TOC contents by 14.1–20.6%. Soil MBC, DOC, and EOC under 1/2OF were significantly higher than under N0, whereas the 1/3OF + 2/3NF treatment had significantly greater POC. The CPMI was improved by organic fertilizer treatment, with 1/2OF treatment being significantly higher than N0 and NF. The proportion of soil aggregate mass with particle sizes &gt;2 mm was significantly greater under N0, while 1/3OF + 2/3NF significantly increased the proportion of particle sizes of 0.5–2 mm. Soil water-stable aggregate-associated organic carbon showed a trend of first increasing and then decreasing, with the largest particle sizes being 1–2 mm. Moreover, organic fertilizer significantly increased soil water-stable aggregate organic carbon compared with N0 and NF. Similarly, the garlic yield increased with organic fertilizer treatment, while 1/3OF + 2/3NF significantly increased the yield by 37.2% and 15.3%, respectively, compared with N0 and NF. Furthermore, SEM analysis indicated that fertilizer regimes could directly affect TOC and labile organic carbon components by affecting aggregate-associated organic carbon. In particular, aggregates with particle sizes of 0.5–2 mm played an important role, indirectly affecting garlic yield and CPMI. These results indicate that organic fertilizer application has the potential to improve soil organic-carbon content and garlic yield; moreover, fully applying organic fertilizer can reduce N fertilizer input while still maintaining an increase in soil organic carbon and crop yield in the short term. However, caution is still needed regarding of the type and quantity of organic fertilizer added in different cropping systems, and with different soil textures.

Effect of Partial Organic Fertilizer Substitution on Heavy Metal Accumulation in Wheat Grains and Associated Health Risks

The partial substitution of chemical fertilizers with organic manure is an important strategy for improving agricultural sustainability. However, its effect on heavy metal (HM) pollution and its potential risk to human health remain unclear. Therefore, a field study was conducted to evaluate the effects of partial organic fertilizer substitution (0, 10%, 20%, 30%, and 40%) on health risks posed by HMs, including Zn, Cu, Ni, Cd, Pb, As, and Cr. The results showed that organic fertilizer substitution significantly increased Cu, Cd, Pb, and As accumulations in the soil. The Zn, Cu, Pb, and As contents were significantly higher in grains grown under organic fertilizer substitution (40%) conditions. The HM contents in the soil and grains were below the safety threshold limits in all treatments. Furthermore, the health risk caused by the exposure to As, Cu, and Zn accounted for 86% of the hazard index (HI) value. The HI value was significantly greater at a substitution ratio of 40% than in the no-nitrogen fertilizer treatment. Ingestion of the wheat grains grown at substitution ratios ≥ 30%) increased the carcinogenic risk of As and the total carcinogenic risk. In conclusion, organic fertilizer substitution at high ratios significantly increased the non-carcinogenic and carcinogenic risks associated with ingesting wheat grain. The optimal organic fertilizer substitution ratio (20%) maintained crop yields and improved soil fertility without increasing the non-carcinogenic or carcinogenic risks to human health. These findings highlight the importance of understanding the impacts of optimal organic fertilizer management in wheat growing systems.

The Effects of Partial Substitution of Fertilizer Using Different Organic Materials on Soil Nutrient Condition, Aggregate Stability and Enzyme Activity in a Tea Plantation.

Fertilization plays a crucial role in enhancing tea production. However, it has been demonstrated that the long-term single application of chemical fertilizer will reduce soil nutrient content and the formation of soil aggregates, which is not conducive to the sustainable development of soil and agriculture. Many studies have shown that partial substitution of chemical fertilizer with organic fertilizer can improve soil physicochemical properties and soil nutrient content. This study compared the effects of different organic materials as substitutes for chemical fertilizer. We partially replaced chemical fertilizer with rabbit manure, wine lees and rapeseed cake, amounting to 30% of the total annual nitrogen application in the field experiment, and we set nine different fertilization methods to assess and analyze the soil nutrient condition, aggregate stability and enzyme activity. The results showed that the experimental soil aggregate mean weight diameter (MWD) and geometric mean diameter (GMD) were significantly increased compared with control (p < 0.05); the aforementioned fertilization methods also decreased the soil aggregate fractal dimension (D), disruption rate (PAD), average weight-specific surface area (MWSSA) and soil erodibility factor (K). The application of the fertilizer containing organic materials and microbial agent increased soil organic carbon (SOC) by 20.7% to 22.6% and total nitrogen (TN) by 34.6% to 38.1%; it also significantly promoted sucrase, urease and protease activities in all aggregate sizes (p < 0.05) and increased the 2-5 mm aggregate content. The correlation coefficients between the SOC and the enzyme activities were 0.18-0.95, and most of them showed an extremely significant positive correlation (p < 0.01). In conclusion, the application of fertilizers containing organic materials and microbial agents can improve soil aggregate stability, aggregate enzyme activity and soil structural stability.

Synergistic effects of earthworms and cow manure under reduced chemical fertilization modified microbial community structure to mitigate continuous cropping effects on Chinese flowering cabbage.

The substitution of chemical fertilizers with organic fertilizers is a viable strategy to enhance crop yield and soil quality. In this study, the aim was to investigate the changes in soil microorganisms, soil chemical properties, and growth of Chinese flowering cabbage under different fertilization treatments involving earthworms and cow manure. Compared with the control (100% chemical fertilizer), CE (30% reduction in chemical fertilizer + earthworms) and CFE (30% reduction in chemical fertilizer + cow dung + earthworms) treatments at soil pH 8.14 and 8.07, respectively, and CFC (30% reduction in chemical fertilizer + cow manure) and CFE treatments increased soil organic matter (SOM), total nitrogen (TN), available nitrogen (AN), and available potassium (AK) contents. Earthworms and cow manure promoted the abundance of Bacillus and reduced that of the pathogens Plectosphaerella and Gibberella. The mantle test revealed that pH was not correlated with the microbial community. Random forest analysis verified that AN, SOM, and TN were important factors that jointly influenced bacterial and fungal diversity. Overall, the synergistic effect of earthworms and cow manure increased soil fertility and microbial diversity, thereby promoting the growth and development of Chinese flowering cabbage. This study enhanced the understanding of how bioregulation affects the growth and soil quality of Chinese flowering cabbage, and thus provided a guidance for the optimization of fertilization strategies to maximize the yield and quality of Chinese flowering cabbage while reducing environmental risks.

Vermi-converted Tea Industry Coal Ash efficiently substitutes chemical fertilization for growth and yield of cabbage (Brassica oleracea var. capitata) in an alluvial soil: A field-based study on soil quality, nutrient translocation, and metal-risk remediation

Although coal ashes (CA) can be converted into an eco-friendly product through vermicomposting, the utility of vermiconverted CA in agriculture still needs to be explored. Therefore, the feasibility of vermicomposted tea industry coal ash (VCA) as an alternative nutrient source for cabbage (Brassica oleracea, var. Capitata) production was evaluated through an on-field experiment in alluvial soil. Two types of vermicomposts were prepared using Eisenia fetida (VCAE) and Lampito mauritii (VCAL) and were applied in different combinations with chemical fertilizers. The results revealed a significant increase in nutrient availability (nitrogen, phosphorus, and potassium) in the soil treated with VCA, alongside a concurrent build-up of soil organic carbon stocks, activation of microbial growth, and enhanced soil enzyme activity. Additionally, VCA application substantially reduced toxic metals in the soil, thereby improving soil health and promoting the uptake of essential nutrients (nitrogen, phosphorus, potassium, iron, manganese, copper, and zinc) in cabbage. VCA application reduced the bioaccumulation of potentially toxic metals (chromium, lead, and cadmium) from coal ash, ensuring safer food production. Notably, a 25 % substitution of chemical fertilizers with VCA and farmyard manure (FYM) led to a two-fold increase in the growth and productivity of cabbage. The economic assessment also indicated that large-scale and sustainable recycling of toxic tea industry coal ash in agriculture is feasible. Hence, by integrating VCA-based nutrient management into agricultural practices, developing nations can take significant strides toward achieving circular economy objectives while addressing environmental challenges associated with CA disposal.

Potential for yield and soil fertility improvement with integration of organics in nutrient management for finger millet under rainfed Alfisols of Southern India.

Finger millet (Eluesine coracana L.) is gaining importance as a food crop with the increasing emphasis on nutritional aspects and drought resilience. However, the average productivity of the crop has stagnated at around 2,000 kg ha-1 in India. Recently released nutrient responsive high yielding varieties are reported to respond better to application of fertilizers/manures. Further, substitution of chemical fertilizers with organic manures to maintain sustainable yields and improve soil health is gaining attention in recent years. Therefore, identifying the appropriate rate and source of nutrition is important to enhance the productivity of finger millet while improving the soil health. A field experiment was conducted during two rainy seasons (July-November, 2018 and 2019) to study the response of finger millet varieties to chemical fertilizers and farmyard manure (FYM) on growth, yields, N use efficiency, N uptake and on soil properties. Two varieties MR-1 and MR-6 were tested with four nutrient management practices viz., unamended control, 100% recommended dose of fertilizers (RDF; 40-20-20 kg NPK ha-1), 50% RDF + 50% recommended dose of nitrogen (RDN) as FYM and 100% RDN as FYM. Among the varieties, MR-6 outperformed MR-1 in terms of growth, yield, N use efficiency and N uptake. The yield enhancement was up to 22.6% in MR-6 compared to MR-1 across the nutrient management practices. Substituting FYM completely or half of the fertilizer dose increased the growth and yield of finger millet compared to application of chemical fertilizers alone. Similarly, the average biomass yield, ears m-2, grain yield, total N uptake and N use efficiency in response to nutrient management practices followed the order of 100% RDN as FYM > 50% RDF + 50% RDN as FYM > 100% RDF. The soil organic carbon, available N, P, K, and S improved by 25.0, 12.9, 5.7, 6.1, and 22.6%, respectively in the plots under higher rate of FYM application (8 Mg ha-1) compared to plots under chemical fertilizers alone. We conclude that substituting chemical fertilizers either completely or by up to 50% with organic manures supplies adequate amounts of nutrients, improves the yield of finger millet, economic returns, and soil properties.

Streptomyces at the Heart of Several Sectors to Support Practical and Sustainable Applications: A Review

This article emphasizes the various contributions of actinobacteria to the well-being of human life on our planet. Agrarian virtues begin with the substitution of chemical fertilizers with bio-fertilizing microorganisms which have a versatile potential for the benefit of soil and plants by playing complementary and interconnected roles. Thus, these microorganisms improve soil health through bioremediation phenomena and the elimination of several non-beneficial microorganisms. In agriculture, these microorganisms can be added to compost as inoculants to speed up the composting process and provide an additional source of beneficial microorganisms for the compost-treated soil. Streptomyces and other actinobacteria can also be used as biotechnological sources of herbicides and insecticides. In the medical and therapeutic sectors, this paper emphasizes the potential of actinobacteria, in particular Streptomyces species, in the production of antibiotics, antioxidant, and anticancer agents, opening up avenues for the creation of molecules with high benefits. In biotechnology, these totipotent microorganisms produce enzymes widely used in several industries, generating considerable revenue. Sporadic data accumulated on these types of microorganisms opens up many new avenues for exploiting these natural biocatalytic resources. Papers published in the last decade have exploded the amount of information that can be put to practical use. To maximize the value of these microorganisms, it would be advisable to create common threads between the themes that bring together the areas of expertise where these microorganisms could potentially be exploited. This bibliographical synthesis is a contribution to the development of a targeted database.

Partial substitution of chemical fertilizer by Trichoderma biofertilizer improved nitrogen use efficiency in wolfberry (Lycium chinense) in coastal saline land.

A two-year field trial was conducted to investigate the effects of partial substitution of chemical fertilizer (CF) by Trichoderma biofertilizer (TF) on nitrogen (N) use efficiency and associated mechanisms in wolfberry (Lycium chinense) in coastal saline land. As with plant biomass and fruit yield, apparent N use efficiency and plant N accumulation were also higher with TF plus 75% CF than 100% CF, indicating that TF substitution promoted plant growth and N uptake. As a reason, TF substitution stabilized soil N supply by mitigating steep deceases in soil NH4 +-N and NO3 -N concentrations in the second half of growing seasons. TF substitution also increased carbon (C) fixation according to higher photosynthetic rate (Pn) and stable 13C abundance with TF plus 75% CF than 100% CF. Importantly, leaf N accumulation significantly and positively related with Pn, biomass, and fruit yield, and structural equation modeling also confirmed the importance of the causal relation of N accumulation coupled with C fixation for biomass and yield formation. Consequently, physiological and agronomical N use efficiencies were significantly higher with TF plus 75% CF than 100% CF. Overall, partial substitution of CF by TF improved N use efficiency in wolfberry in coastal saline land by stabilizing soil N supply and coupling N accumulation with C fixation.

Full substitution of chemical fertilizer by organic manure decreases soil N2 O emissions driven by ammonia oxidizers and gross nitrogen transformations.

Replacing synthetic fertilizer by organic manure has been shown to reduce emissions of nitrous oxide (N2 O), but the specific roles of ammonia oxidizing microorganisms and gross nitrogen (N) transformation in regulating N2 O remain unclear. Here, we examined the effect of completely replacing chemical fertilizer with organic manure on N2 O emissions, ammonia oxidizers, gross N transformation rates using a 13-year field manipulation experiment. Our results showed that organic manure reduced cumulative N2 O emissions by 16.3%-210.3% compared to chemical fertilizer. The abundance of ammonia oxidizing bacteria (AOB) was significantly lower in organic manure compared with chemical fertilizer during three growth stages of maize. Organic manure also significantly decreased AOB alpha diversity and changed their community structure. However, organic manure substitution increased the abundance of ammonia oxidizing archaea and the alpha diversity of comammox Nitrospira compared to chemical fertilizer. Interestingly, organic manure decreased organic N mineralization by 23.2%-32.9%, and autotrophic nitrification rate by 10.5%-45.4%, when compared with chemical fertilizer. This study also found a positive correlation between AOB abundance, organic N mineralization and gross autotrophic nitrification rate with N2 O emission, and their contribution to N2 O emission was supported by random forest analysis. Our study highlights the key roles of ammonia oxidizers and N transformation rates in predicting cropland N2 O.

Impacts of Partial Substitution of Chemical Fertilizer with Organic Fertilizer on Soil Organic Carbon Composition, Enzyme Activity, and Grain Yield in Wheat-Maize Rotation.

This study explored the effect of the long-term partial replacement of chemical fertilizer with organic fertilizer on soil organic carbon composition, enzyme activity, and crop yields in the wheat-maize rotation area of northern Anhui, China. This study also specified the proper amount of organic fertilizer replacement that should be used for chemical fertilizer. Different fertilization modes were used (no fertilization, CK; chemical fertilizer, CF; chemical fertilizer and straw returning, CF + S; chemical fertilizer, straw returning, and straw decomposition agent, CF + S + DA; 70% chemical fertilizer and 50% organic fertilizer, 70% CF + 50% OF; 70% chemical fertilizer, 50% organic fertilizer and straw returning, 70% CF + 50% OF + S; 50% chemical fertilizer and 100% organic fertilizer, 50% CF + 100% OF; and 50% chemical fertilizer, 100% organic fertilizer, and straw returning, 50% CF + 100% OF + S). Variations in the organic carbon composition, enzyme activity, soil pH, and crop yields in the wheat-maize rotation under different fertilization treatments were analyzed. The results showed that the replacement of chemical fertilizer with organic fertilizer results in improved crop yields in wheat-maize rotation. The long-term partial replacement of chemical fertilizer with organic fertilizer can increase the quality of soil humus, alleviate soil acidification, and improve soil enzyme activity. Straw returning and organic fertilizer application can considerably raise the activities of urease, acid phosphatase, and nitrate reductase in soil. The soil pH of the CF treatment was reduced compared to the CK treatment, while organic fertilizer application alleviated soil acidification when compared to CF treatment. Organic fertilization increases the total organic carbon content of the soil, which was 19.6~85.5% higher than in the CK treatment. Applying straw and organic fertilizer significantly increased the ratio of the humic/fulvic acid in the soil. The soil active carbon forms of the soil with the application of organic fertilizer and straw returning were significantly higher than those of the CK and CF treatments. This study suggests that the optimal fertilizer management option in northern Anhui's wheat-maize rotation area is to replace 50% of the chemical fertilizer with organic fertilizer, and to fully return straw to the field. This would include 150 kg N h·m-2, 60 kg P2O5 h·m-2, 50 kg K2O h·m-2, 6000 kg organic fertilizer h·m-2, and full straw return to the field.

Responses of water‐stable aggregates, their associated organic carbon and crop yield to the application of biogas slurry in a fluvo‐aquic soil of the North China plain

AbstractCrop productivity under intensive agriculture depends on the maintenance of fertility and soil structure. Chemical fertilizers are effective in supplying nutrients for crops but eventually lead to loss of the soil organic carbon that is important in supporting soil structure. Biogas slurry is an alternative to chemical fertilizers that potentially can both provide nutrients and promote organic carbon content. A field experiment was conducted to compare the effects of applying biogas slurry (BS), chemical fertilizer (CF) or a combination of both with 50% of nitrogen derived from each (BSCF) and no fertilizer application control (CK) to a fluvo‐aquic soil of the North China Plain. All fertilizer application treatments had equal nutrient supply and were continuously applied over 4 years. Annual yields of wheat and maize were determined. Water‐stable aggregates in size classes &gt;5 mm, 2–5 mm, 0.25–2 mm, 0.053–0.25 mm and &lt;0.053 mm in the topsoil of 20 cm were separated by wet sieving; mean weight diameter (MWD), geometric mean diameter (GMD), percentage of aggregates destruction (PAD) and fractal dimension (D) were derived. The concentrations of organic carbon associated with the aggregates were measured, and the distribution of soil organic carbon (SOC) was quantified. Fertilizer application treatments enhanced total crop yield by 49.1%–75.0%. Fertilizer application also increased the mass proportions of water‐stable macro‐aggregates by 81.6%–164.4%, MWD by 100.0%–264.3%, GMD by 54.5%–227.3%, while decreasing PAD by 15.4%–47.8% and D by 1.0%–3.8% (all relative to CK). The highest proportions of macro‐aggregates, the greatest aggregate stability and the greatest crop yield all resulted from BSCF. All fertilizer application treatments substantially increased the SOC content of water‐stable aggregates, with greater relative contribution in macro‐aggregates. Increased SOC in macro‐aggregates was mainly attributable to mass proportion changes rather than changes in their SOC concentrations. However, SOC concentration tended to account for a larger proportion of the total changes in micro‐aggregates. BSCF also produced the highest total soil organic carbon stocks in aggregates (40.3% and 57.3% greater than CF and CK, respectively). Our work demonstrates that half substitution of chemical fertilizer with biogas slurry is a practical management to enhance soil aggregation and its stability that is associated with a higher crop yield than either treatment individually. It also promotes organic carbon accumulation in soil aggregates, which will support sustainable agricultural development in fluvo‐aquic soil.