Organic Fertilization Regimes Research Articles

Long-term organic fertilization improves the productivity of kiwifruit (Actinidia chinensis Planch.) through increasing rhizosphere microbial diversity and network complexity

The effects of organic soil amendments on rhizosphere microbial communities have been studied in many crop species. However, there is little research on rhizosphere microbial communities in kiwifruit (Actinidia chinensis Planch.), which is a valuable fruit tree species. Therefore, the objective of this study was to explore changes in community composition and co-occurrence networks of bacteria and fungi in the rhizosphere of kiwifruit under long-term organic fertilization regimes. Organic amendments (mainly pig and sheep dung compost) were applied at rates of 10, 20, and 40 Mg ha−1 y−1 over 9 years, with chemical fertilizers (N 287.5, P 115 kg ha−1 y−1, and K 115 kg ha−1 y−1) applied as the control. Results showed that in addition to soil pH and nutrients (e.g., carbon and nitrogen), the yield and quality of kiwifruit were improved by the application of organic amendments compared with the control. Organic amendments also increased bacterial diversity and relative abundance of plant growth-promoting bacteria (including Pseudomonas, Chrysosporium, and Burkholderia) in the rhizosphere of kiwifruit. Conversely, the relative abundance of plant pathogenic fungi (including Fusarium) was reduced due to the application of organic amendments. Network analysis indicated that organic amendments stimulated the formation of functional groups and activated antagonism or mutualism between microbial taxa. Spearman's correlation analysis revealed that the relative abundance of potentially beneficial microorganisms including Burkholderia and Devosia was positively correlated with fruit yield or quality. In conclusion, long-term organic fertilization regimes might improve the productivity of kiwifruit by increasing rhizosphere microbial diversity and network complexity.

Productivity and Quality of Kohlrabi Grown in a Newly Reclaimed Sandy Soil Using Organic and Mineral-N Fertilizer regimes with or without Spraying of Spirulina platensis Extract

The current study aimed to investigate the influence of organic manure and/or mineral N-fertilizer with or without Spirulina platensis alga cells extract on growth, yield and quality of kohlrabi knobs. Field experiments were carried out on Kohlrabi (Brassica oleracea var. gongylodes) cv. White Vienna at the Experimental Farm of the Environmental Studies and Research Institute, El-Sadat City University, Egypt, during the winter seasons of 2015/2016 and 2016/2017 under drip irrigation systems. The obtained results showed that using 50% mineral-N + 50% organic-N combined with spirulina extract improved plant growth, yield and knob quality compared to other N-fertilizer regimes. Therefore, this treatment gave the best growth and increased total yield with the best knob quality as compared with no added. The highest content of nitrate in knobs (473.85 mg kg-1 DW) was recorded by using 100% mineral-N treatment (as an average in both seasons). Whereas, adding 100% organic-N recorded the lowest content of nitrate in knobs (83.45 mg kg-1 DW) as an average of both seasons. It is worthy to mention that nitrate concentration in tested kohlrabi knobs is still in the safe border for human consumption.

Reshaping the rhizosphere microbiome by bio-organic amendment to enhance crop yield in a maize-cabbage rotation system

Characterizing the rhizosphere microbial community composition associated with enhanced crop yield is an important first step towards understanding the role of the microbiota in soil fertility. In the present study, we conducted a two-seasons field experiment in a maize-cabbage cropping system under chemical (CF), organic (OF) and bio-organic (BOF) fertilizer regimes as a model to investigate the combinatory effect of fertilizer treatment and crop type on rhizosphere soil microbiota by targeted sequencing of both the bacterial and fungal communities. The two-seasons sustainable application of bio-organic fertilizer (BOF) containing Trichoderma effectively increased maize and cabbage yields, whereas organic fertilizer (OF) increased but not significant, compared to the application of chemical fertilizer (CF). Both fertilizer treatment and crop type induced a significant effect on soil physiochemical properties and were the major factors that impacted the composition of the rhizosphere soil microbiome. Relative abundances of Trichoderma were significantly enhanced in the BOF treatment, compared to the OF and CF treatments, and exhibited significant positive relationships with crop yield improvement. The application of bio-organic fertilizer may enhance the growth promotion effect of Trichoderma and increase the abundance of potentially beneficial microbial groups such as the genera Cladorrhinum and Massilia, which were found to be highly correlated to increased crop yields. Overall, the influence of bio-organic fertilizer on crop yield is proposed to be through mechanisms by introduction of the target strain NJAU 4742 and stimulation of a potentially beneficial microbial consortia, in combination with alterations in fungal and bacterial composition and abundance, leading to an enhancement in crop yield.

Linking cropland ecosystem services to microbiome taxonomic composition and functional composition in a sandy loam soil with 28-year organic and inorganic fertilizer regimes

The ability of soil microorganisms to uphold a variety of ecosystem services is of increasing interest, but our understanding of the linkage between cropland ecosystem services and the soil microbiome under long-term different fertilizer regimes is still limited. Here, we measured 15 response variables commonly used as indicators of cropland ecosystem services, and employed a shotgun metagenomic sequencing technology to determine microbiome taxonomic composition and functional composition in a sandy loam soil amended with organic and inorganic fertilizers for 28 years. Long-term application of fertilizers had overall positive effects on the variables that indicate soil C and nutrient status, organic material decomposition, nutrient transformation, and plant productivity, but the strength of these effects differed between organic and inorganic fertilization. In long term, organic fertilizers significantly increased the abundance of Sphingomonas and Acidobacteria as well as genes involved in C and N metabolism and degradation of aromatic organic compounds. The observed differences in the indicators of overall biological activity, litter decomposition, nutrient transformation, cropland fertility and productivity were associated with changes in taxonomic composition and functional composition of the soil microbiome. Network analysis revealed that soil organic C, total N, L-leucine aminopeptidase, phosphatase, microbial biomass C and N, and the multifunctionality index showed strong positive associations with Acidobacterium, Lysobacter and Nitrososphaera. These microbes are implicated in the decomposition of organic material, soil C and N transformation, and plant growth promotion. The present study deepens our understanding of the relationship between the soil microbiome and agro-ecosystem functioning, and provides support for the use of organic fertilization strategy to enhance multiple ecosystem services in croplands.

Effects of different nitrogen fertilizers on two wheat cultivars: An integrated approach.

Investigation of cultivated plant physiology grown under low energy input plays an important role to indicate their fitness to the new environmental conditions. The durum‐wheat cultivars Creso and Dylan were tested to evaluate the growth, production, and proteomic and transcriptomic profiles of the crop under different synthetic and organic nitrogen fertilization regimes. In this work, a two‐dimensional gel electrophoresis (2‐DE) approach combined with liquid chromatography–mass spectrometry (LC–MS) was used to investigate the protein changes induced by the use of different nitrogen sources (hydrolysate of proteins 1 and 2, rhizovit, synthesis, leather) on wheat plants. Proteomic studies were integrated with qPCR analysis of genes related to glutamine synthetase/glutamine‐2‐oxoglutarate aminotransferase (GS‐GOGAT) and tricarboxylic acid (TCA) metabolic pathways because most relevant for nitrogen‐dependent plants growth. The proteomic analysis lead to the isolation of 23 spots that were able to distinguish the analyzed samples. These spots yielded the identification of 60 proteins involved in photosynthesis, glycolysis, and nitrogen metabolism. As an example, the quinone oxidoreductase‐like protein and probable glutathione S‐transferase GSTU proteins were identified in two spots that represents the most statistically significant ones in Dylan samples. Transcript analysis indicated that related genes exhibited different expression trends; the heat map also revealed the different behaviors of the hydrolysates of the proteins 1 and 2 nitrogen sources. The effects of nitrogenous fertilizers at the proteomic and agronomic levels revealed that plants fertilized with synthesis or rhizovit gave the best results concerning yield, whereas rhizovit and protein hydrolysates were most effective for proteins content in the grain (% of dry weight). Therefore, all parameters measured in this study indicated that different kinds of nitrogen fertilization used have a relevant impact on plant growth and production.

Contrasting responses of bacterial and fungal communities to aggregate-size fractions and long-term fertilizations in soils of northeastern China

Soils, with non-uniform distribution of nutrients across different aggregate-size fractions, provide spatially heterogeneous microhabitats for microorganisms. However, very limited information is available on microbial distributions and their response to fertilizations across aggregate-size fractions in agricultural soils. Here, we examined the structures of bacterial and fungal communities across different aggregate-size fractions (2000–250 μm, 250–53 μm and <53 μm) in response to 35-years organic and/or chemical fertilization regimes in the soil of northeastern China by phospholipid fatty acid (PLFA) and high throughput sequencing (HTS) technology. Our results show that larger fractions (>53 μm), especially 250–53 μm aggregates, which contain more soil C and N, are associated with greater microbial biomass and higher fungi/bacteria ratio. We firstly reported the fungal community composition in different aggregate-size fractions by HTS technology and found more Ascomycota but less Zygomycota in larger fractions with higher C content across all fertilization regimes. Fertilization and aggregate-size fractions significantly affect the compositions of bacterial and fungal communities although their effects are different. The bacterial community is mainly driven by fertilization, especially chemical fertilizers, and is closely related to the shifts of soil P (phosphorus). The fungal community is preferentially impacted by different aggregate-size fractions and is more associated with the changes of soil C and N. The distinct responses of microbial communities suggest different mechanisms controlling the assembly of soil bacterial and fungal communities at aggregate scale. The investigations of both bacterial and fungal communities could provide a better understanding on nutrient cycling across aggregate-size fractions.

Soil labile organic carbon fractions and soil organic carbon stocks as affected by long-term organic and mineral fertilization regimes in the North China Plain

To improve C sequestration in soils and mitigate climate change, it is essential to understand how nutrient management strategies impact on soil organic carbon (SOC) stocks and labile fractions. This study was designed to explore changes in soil bulk density (BD), SOC concentrations, SOC stocks and soil labile organic C fractions (mineralizableC (Cmin), microbial biomass C (MBC), dissolved organic C (DOC), particulate organic C (POC), light fraction organic C (LFOC) and permanganate oxidizable C (KMnO4-C)) under 26-year fertilization regimes in a wheat-maize rotation system in the North China Plain. Soil from the following six treatments was analyzed: (1) Control with no amendment addition (CK); (2) Standard rate of mineral fertilizer treatment (SMF) reflecting local farmers' practice; (3) Standard rate of organic manure treatment (SMA) with total N input equal to SMF; (4) Half the standard rate of mineral fertilizer plus half the standard rate of organic manure treatment (1/2 SMF+1/2 SMA); (5) Double standard rate of mineral fertilizer treatment (DMF); (6) Double standard rate of organic manure treatment (DMA). Results showed that all long-term fertilization regimes significantly decreased BD in topsoil compared to CK except for SMF, with treatments that included organic manure resulting in the lowest BDs. Treatments that included organic manure had significantly higher SOC concentrations and stocks than mineral or unfertilized treatments. The organic manure treatments also had higher concentrations of non-labile C but at the same time a higher proportion of labile C than the mineral or unfertilized treatments. This was confirmed by the carbon management index (CMI) which was significantly increased by organic manure addition. Control and mineral fertilized treatments had higher efficiencies of C retention (RE) from added inputs (crop residues only). Differences in Cmin, POC and KMnO4-C were affected by differences in MA-C, however, changes in rhizodeposition-C, stubble-C and root-C significantly affected DOC, MBC and LFOC. This study demonstrates that fertilization strategies that include organic manure can increase the pool of stable C in the surface soil layer, while at the same time increasing concentrations and proportions of labile C. Organic manure use can therefore contribute to improved nutrient cycling services and higher soil quality in the North China Plain.

Wheat and Rice Growth Stages and Fertilization Regimes Alter Soil Bacterial Community Structure, But Not Diversity.

Maintaining soil fertility and the microbial communities that determine fertility is critical to sustainable agricultural strategies, and the use of different organic fertilizer (OF) regimes represents an important practice in attempts to preserve soil quality. However, little is known about the dynamic response of bacterial communities to fertilization regimes across crop growth stages. In this study, we examined microbial community structure and diversity across eight representative growth stages of wheat-rice rotation under four different fertilization treatments: no nitrogen fertilizer (NNF), chemical fertilizer (CF), organic–inorganic mixed fertilizer (OIMF), and OF. Quantitative PCR (QPCR) and high-throughput sequencing of bacterial 16S rRNA gene fragments revealed that growth stage as the best predictor of bacterial community abundance and structure. Additionally, bacterial community compositions differed between wheat and rice rotations. Relative to soils under wheat rotation, soils under rice rotation contained higher relative abundances (RA) of anaerobic and mesophilic microbes and lower RA of aerophilic microbes. With respect to fertilization regime, NNF plots had a higher abundance of nitrogen–fixing Cyanobacteria. OIMF had a lower abundance of ammonia-oxidizing Thaumarchaeota compared with CF. Application of chemical fertilizers (CF and OIMF treatments) significantly increased the abundance of some generally oligotrophic bacteria such those belonging to the Acidobacteria, while more copiotrophic of the phylum Proteobacteria increased with OF application. A high correlation coefficient was found when comparing RA of Acidobacteria based upon QPCR vs. sequence analysis, yet poor correlations were found for the α- and β- Proteobacteria, highlighting the caution required when interpreting these molecular data. In total, crop, fertilization scheme and plant developmental stage all influenced soil microbial community structure, but not total levels of alpha diversity.

Effect of nano-silicon foliar application on safflower growth under organic and inorganic fertilizer regimes

Abstract Silicon nanoparticles have distinctive physicochemical characteristics and are able to enter into plants and impact the metabolism of plants as well as improve plant growth and yield under unfavourable environmental conditions. Besides, low soil organic matter content, imbalanced nutrient and inadequate water supply may adversely affect crop productivity in semiarid areas. To understand the effects of foliar spray of silicon dioxide nanoparticles (nSiO2) with application of farmyard manure (FYM) or inorganic fertilizer on morpho-physiological traits and yield of safflower, a field experiment was carried out in a highland semiarid region of Maragheh, northwest Iran. The experiment consisted of two levels of nSiO2 (0 and 20 mM) and four fertilizer regimes (control, 15 t ha−1 FYM, 30 t ha−1 FYM, 90 kg ha−1 N-P-K chemical fertilizer). Safflower plants were treated with nSiO2 suspension at leaf development, branching and capitulum emergence stages. Although the nSiO2 significantly improved some growth parameters such as canopy spread, stem diameter, plant height, ground cover and the number of achenes in capitulum, it did not affect achene yield and harvest index. However, fertilizer treatments considerably affected most of morpho-physiological traits, achene yield and yield components. The result showed that the best growth and the highest achene yield were achieved by application of 30 t ha−1 FYM before sowing. Application of high FYM increased the achene yield by 48% compared to the control, however, application of N-P-K chemical fertilizer or of 15 t ha−1 FYM improved achene yield only up to 17% over the no fertilizer condition. Moreover, this work revealed some positive effects of exogenous application of nSiO2 on safflower growth. This finding suggests that application of organic fertilizers with foliar spray of nSiO2 can improve safflower production and is an advisable agronomic option.

NDICEA Calibration and validation on a northern UK soil

Modelling nitrogen (N) dynamics in agricultural soils can improve our understanding of the nitrogen cycle in rotational systems. NDICEA (Nitrogen Dynamics in Crop rotations in Ecological Agriculture) is a tool to model soil N dynamics for maximum nitrogen use efficiency (NUE) and minimum environmental impacts from agricultural fertilization. In this study the model was calibrated using actual soil mineral N data from 2 years of a long-term organic versus conventional systems comparison trial. Calibration data was used from only the organic crop protection treatments for an organic crop rotation under (a) organic fertility management (ORG-OF) and (b) conventional fertility management (ORG-CF), and a conventional crop rotation under (c) organic fertility management (CON-OF), and (d) conventional fertility management (CON-CF). The model was subsequently validated using the same four treatment combinations from the conventional crop protection treatments. The accuracy of soil mineral N predictions was consistently improved after calibration, with the model performing best under organic fertilization regimes; reflecting the model’s original purpose. The lack of difference among treatments for the calibrated soil parameters demonstrated that the calibration procedure was robust and could result in a model that is superior to the non-calibrated one, and specific for this soil type, regardless of soil management practices. The simplification of complex biological processes into model parameters limits the use of NDICEA as a tool to explain the underlying processes driving soil N dynamics. Nevertheless it could be a useful tool for visualising field-scale N dynamics, allowing farmers and advisors to explore the impact of changing management factors on within-field N efficiency.

Soil microbial community structure and function are significantly affected by long-term organic and mineral fertilization regimes in the North China Plain

An improved understanding of the complex interactions and relationships in the soil ecosystem is essential to predict the impact of farming practices on soil quality and its capacity for agricultural production. This study aims to improve our understanding of the impacts of fertilization strategy on key indicators of soil biological and chemical quality. We studied soils from a winter wheat-summer maize rotational experiment in the North China Plain with six different fertility treatments: no amendments (CK); standard mineral fertilizer treatment (SMF) or standard organic manure treatment (SMA) reflecting local farmer practice; mixed treatment with fertilizer and manure at half the rates for the SMF and SMA treatments (1/2 SMF+1/2 SMA); double mineral fertilizer treatment (DMF); and double organic manure treatment (DMA). Soil organic C (SOC), total N (TN), total P (TP), pH, and dissolved organic C (DOC) and N (DON) and microbial biomass C (Cmic) and N (Nmic) were determined using standard methods. Soil bacterial community structure was assessed by denaturing gradient gel electrophoresis (DGGE), and activities for 10 extracellular enzymes (EEAs) were measured as indicators of soil function. Repeated application of either organic manure or mineral fertilizer increased SOC, TN, TP, DOC, DON, Cmic and Nmic, and decreased soil pH. Higher rates of organic manure fertilization significantly affected soil chemical properties compared to the lower rate. Soil bacterial community structure was significantly altered by the long-term fertilization regimes and diversity was significantly higher in the double manure rate treatment relative to mineral fertilizer. The higher urease, α-glycosidase, N-acetyl-β-glucosaminidase, l-leucine aminopeptidase (involved in N cycling), β-glucosidase, β-xylosidase and β-cellobiosidase (involved in C cycling), and alkaline phosphatase (involved in P cycling) activities for organic manure fertilized soils reflected a higher nutrient cycling capacity compared to mineral fertilized and control plots. Soil bacterial community diversities increased with Cmic and variations in EEAs were strongly correlated with soil DOC availability. Our study has demonstrated that a long-term fertilization strategy can be used to improve soil quality. Clearly, the use of organic fertilizers where available, is a win–win strategy for maintaining soil quality and crop productivity, while ensuring the delivery of soil ecosystem services into the future.

Effect of Organic Fertilizers, Irrigation Regimes and Biological Amendments on Growth and Production of Sweet Pepper

ORGANIC fertilizer regimes consisting of combinations of compost, liquid fertilizers and conventional fertilizer with or without biological amendments (Rhizosphere bacteria and vascular arbuscular mycorrhiza, VAM) were evaluated under three irrigation regimes (60, 80 and 100% of evapo-transpirantsio, ET) in two experiments with open field pepper grown in peat-based substrate. Therefore, field experiments were conducted at private farm, near Mansoura City, Dakahlia Governorate, Egypt, during summer seasons of 2012 and 2013. The irrigation regime treatments were randomly distributed among the main plots, organic fertilizer treatments arranged among the sub plots, while biological amendment treatments were allocated as sub-sub plots.

Interactive Effect of Forage Mixing Rates and Organic Fertilizers on the Yield and Nutritive Value of Berseem Clover (&lt;i&gt;Trifolium alexandrinum&lt;/i&gt; L.) and Annual Ryegrass (&lt;i&gt;Lolium multiflorum&lt;/i&gt; Lam.)

Berseem clover (Trifolium alexandrinum L.) is the main winter forage legume in Egypt. Despite that the yield and protein content of berseem clover are high, it is characterized by low dry matter content especially in the 1st cut. Intercropping berseem clover with forage grasses, especially annual ryegrass (Lolium multiflorum Lam.) is a recommended technique to produce higher forage yield with better balanced nutritional quality. However, little is known about the performance of these proposed mixtures under the arising organic farming system in Egypt. Organic farming and the application of organic fertilizers (compost and poultry manure) are receiving increased attention in the last few years. Thus, the current study was carried out on the winter season of two successive years (2012 and 2013) in the experimental station of SEKEM organic farm, Egypt. Main aim was to investigate the variation in 1st cut forage yield and nutritive value of berseem clover and annual ryegrass, grown in pure stands and with three mixing rates, under three organic fertilization regimes (compost, poultry litter, and no fertilization). Nutritive value was judged through investigating the crude protein (CP), total carbohydrates (TC), and fiber fractions (NDF, ADF, and ADL). Results revealed significant two-way interaction between the forage treatments and the fertilization regimes for all the studied parameters. In general, mixing berseem clover with annual ryegrass, fertilized by compost or poultry litter resulted in significantly higher forage yield, dry matter content, and balanced CP, TC, and fiber fractions, compared to the pure stands.

Effect of organic and nitrogen fertilization on selected components in potato tubers grown in a simplified crop rotation

Fertilization is one of the factors of agro-technical practice that determines potato yield volume and quality. This research involved the early table potato cultivar Bila grown in the first year of the tenth (2006) and the eleventh rotation cycle (2009) in a long-term, static field experiment (set up in 1979). A three-year simplified crop rotation included potato – winter rye 1 – winter rye 2. The experimental factors covered: I organic fertilization (without FYM and with FYM at the amount of 30 t ha-1), II nitrogen doses 0, 60, 120, 180 kg N ha-1 under potato and 0, 40, 80, 120 kg N ha-1 under rye. The aim of the present research was to evaluate the yielding and content of selected chemical components of the tubers of cv. Bila potato grown in a simplified system depending on different organic and mineral fertilization regimes, implemented for many years. The results show a significantly positive effect of FYM and nitrogen fertilization on the tuber yield volume and on the content of total protein and magnesium, as well as a negative effect on the content of nitrates(V). However, FYM fertilization increased but nitrogen fertilization decreased the content of ascorbic acid. The highest nutritive value of tubers was achieved after the application of 60 kg N ha -1 . However, a dose higher than 120 kg N ha -1 applied with FYM increased the content of nitrates(V) above the toxicity threshold (200 mg NO3 ¯ kg -1 of the fresh product).

Changes in soil carbon and crop yield over 60 years in the Zurich Organic Fertilization Experiment, following land‐use change from grassland to cropland

AbstractChanges in land‐use and agricultural management affect soil organic C (SOC) storage and soil fertility. Grassland to cropland conversion is often accompanied by SOC losses. However, fertilization, crop rotation, and crop residue management can offset some SOC losses or even convert arable soils into C sinks. This paper presents the first assessment of changes in SOC stocks and crop yields in a 60‐year field trial, the Zurich Organic Fertilization Experiment A493 (ZOFE) in Switzerland. The experiment comprises 12 treatments with different organic, inorganic and combined fertilization regimes. Since conversion to arable land use in 1949, all treatments have lost SOC at annual rates of 0.10–0.25 t C ha−1, with estimated mean annual C inputs from organic fertilizers and aboveground and belowground plant residues of 0.6–2.4 t C ha−1. In all treatments, SOC losses are still in progress, indicating that a new equilibrium has not yet been reached. Crop yields have responded sensitively to advances in plant breeding and in fertilization. However, in ZOFE high yields can only be ensured when mineral fertilizer is applied at rates typical for modern agriculture, with yields of main crops (winter wheat, maize, potatoes, clover‐grass ley) decreasing by 25–50% when manure without additional mineral fertilizer is applied. ZOFE shows that land‐use change from non‐intensively managed grassland to cropland leads to soil C losses of 15–40%, even in rotations including legumes and intercrops, improved agricultural management and organic fertilizer application.

Effects of Previous Crop Management, Fertilization Regime and Water Supply on Potato Tuber Proteome and Yield

There is increasing concern about the sustainability and environmental impacts of mineral fertilizer use in agriculture. Increased recycling of nutrients via the use of animal and green manures and fertilizers made from domestic organic waste may reduce reliance on mineral fertilizers. However, the relative availability of nutrients (especially nitrogen) is lower in organic compared to mineral fertilizers, which can result in significantly lower yields in nutrient demanding crops such as potato. It is therefore important to gain a better understanding of the factors affecting nutrient use efficiency (yield per unit fertilizer input) from organic fertilizers. Here we show that (a) previous crop management (organic vs. conventional fertilization and crop protection regimes), (b) organic fertilizer type and rate (composted cattle manure vs. composted chicken manure pellets) and (c) watering regimes (optimized and restricted) significantly affected leaf chlorophyll content, potato tuber N-concentration, proteome and yield. Protein inference by gel matching indicated several functional groups significantly affected by previous crop management and organic fertilizer type and rate, including stress/defense response, glycolysis and protein destination and storage. These results indicate genomic pathways controlling crop responses (nutrient use efficiency and yield) according to contrasting types and rates of organic fertilizers that can be linked to the respective encoding genes.

Metabolite profiling of Komatsuna (Brassica rapa L.) field-grown under different soil organic amendment and fertilization regimes

Among agricultural soil fertility management options, the environmental benefits of organic amendments have recently drawn particular attention. However, little information exists about their effects on crop metabolites or quality. Field plots of Komatsuna (Brassica rapa L. var. perviridis) were planted in a fractional factorial design with the following treatments: soil amendments of cattle manure (0, 2 or 4 kg m−2), wheat straw (0, 0.05 or 0.1 kg m−2), fast release nitrogen (N) (0, 6 or 12 g N m−2 of ammonium sulfate), slow release N (0, 3 or 6 g N m−2 of coated ammonium nitrate), phosphorus (P) [0, 5 or 10 g phosphorus pentoxide (P2O5) m−2 of lime superphosphate] and potassium (K) [0, 6 and 12 g potassium oxide (K2O) m−2 as potassium sulfate]. Metabolite profiling was carried out using a gas chromatograph/mass spectrometer (GC/MS), which yielded 62 and 67 metabolites in the leaves and the petioles, respectively. Metabolite peak areas were subjected to principal component analysis (PCA). The first component accounted for 44.1% of the total variance and bore a close relationship to N. The third component accounted for 8.8% of the total variance and was used to distinguish between different levels of manure application. An analysis of variance (ANOVA) of treatment factor effects on individual metabolites showed that the three most significant factors, from highest to lowest, were N absorption, manure amendments and slow release N. The effects of the manure amendments were not fully explained by its attendant N, P or K inputs. This result raises the question as to what mechanisms may bring about the metabolic changes caused by the manure amendment. The current findings will serve to direct further studies on the relationship between crop quality and cultivation procedures and will lead to more efficient quality control methods.

Comparison of the Phenolic Compounds, Carotenoids and Tocochromanols Content in Wheat Grain under Organic and Mineral Fertilization Regimes

A field study was performed to evaluate the effect of mineral (NPK) and organic-based fertilizers such as compost (C), manure (FYM) and meat and bone meal (MBM) on the appearance (dimensions and color) of spring wheat kernels and on the total content in grain of main its phytochemicals (polyphenols, carotenoids and tocochromanols) and phenolic acids composition. Total phenolic compounds were determined using the Folin-Ciocalteu assay after alkaline hydrolysis of grain and carotenoids were analyzed spectrophotometrically. Composition of tocochromanols and phenolic acids was determined using RP-HPLC techniques. Only insignificant differences in the appearance of kernels and small changes in the content and composition of grain phytochemicals were noted between the studied fertilization systems. Among the analyzed phytochemicals the greatest variation was observed in the group of polyphenol compounds, with a stated increase of their total content of 6.7 and 11.2% in grain fertilized with MBM and compost, respectively. Simultaneously the grain from organic fertilization contained significantly less phenolic acids, and the decrease in their content ranged from 10.0% for FYM to 24.8% for MBM+EM-1. Organically and conventionally fertilized grain had similar amounts of tocochromanols and carotenoids. Comparison of MBM and MBM+EM-1 variants showed that application of effective microorganisms decreased carotenoids and tocochromanols content by 8.5 and 9.7%, respectively.

Microbial composition and diversity of an upland red soil under long-term fertilization treatments as revealed by culture-dependent and culture-independent approaches

Fertilization is an important agricultural practice for increasing crop yields. In order to maintain the soil sustainability, it is important to monitor the effects of fertilizer applications on the shifts of soil microorganisms, which control the cycling of many nutrients in the soil. Here, culture-dependent and culture-independent approaches were used to analyze the soil bacterial and fungal quantities and community structure under seven fertilization treatments, including Control, Manure, Return (harvested peanut straw was returned to the plot), and chemical fertilizers of NPK, NP, NK, and PK. The objective of this study was to examine the effects on soil microbial composition and diversity of long-term organic and chemical fertilizer regimes in a Chinese upland red soil. Soil samples were collected from a long-term experiment station at Yingtan (28°15′N, 116°55′E), Jiangxi Province of China. The soil samples (0–20 cm) from four individual plots per treatment were collected. The total numbers of culturable bacteria and fungi were determined as colony forming units (CFUs) and selected colonies were identified on agar plates by dilution plate methods. Moreover, soil DNAs were extracted and bacterial 16S rRNA genes and fungal 18S rRNA genes were polymerase chain reaction amplified, and then analyzed by denaturing gradient gel electrophoresis (DGGE), cloning, and sequencing. The organic fertilizers, especially manure, induced the least culturable bacterial CFUs, but the highest bacterial diversity ascertained by DGGE banding patterns. Chemical fertilizers, on the other hand, had less effect on the bacterial composition and diversity, with the NK treatment having the lowest CFUs. For the fungal community, the manure treatment had the largest CFUs but much fewer DGGE bands, also with the NK treatment having the lowest CFUs. The conventional identification of representative bacterial and fungal genera showed that long-term fertilization treatments resulted in differences in soil microbial composition and diversity. In particular, 42.4% of the identified bacterial isolates were classified into members of Arthrobacter. For fungi, Aspergillus, Penicillium, and Mucor were the most prevalent three genera, which accounted for 46.6% of the total identified fungi. The long-term fertilization treatments resulted in different bacterial and fungal compositions ascertained by the culture-dependent and also the culture-independent approaches. It was evident that more representative fungal genera appeared in organic treatments than other treatments, indicating that culturable fungi were more sensitive to organic than to chemical fertilizers. A very notable finding was that fungal CFUs appeared maximal in organic manure treatments. This was quite different from the bacterial CFUs in the manure, indicating that bacteria and fungi responded differently to the fertilization. Similar to bacteria, the minimum fungal CFUs were also observed in the NK treatment. This result provided evidence that phosphorus could be a key factor for microorganisms in the soil. Thus, despite the fact that culture-dependent techniques are not ideal for studies of the composition of natural microbial communities when used alone, they provide one of the more useful means of understanding the growth habit, development, and potential function of microorganisms from soil habitats. A combination of culture-dependent and culture-independent approaches is likely to reveal more complete information regarding the composition of soil microbial communities. Long-term fertilization had great effects on the soil bacterial and fungal communities. Organic fertilizer applications induced the least culturable bacterial CFUs but the highest bacterial diversity, while chemical fertilizer applications had less impact on soil bacterial community. The largest fungal CFUs were obtained, but much lower diversity was detected in the manure treatment. The lowest bacterial and also fungal CFUs were observed in the NK treatment. The long-term fertilization treatments resulted in different bacterial and fungal compositions ascertained by the culture-dependent and also the culture-independent approaches. Phosphorus fertilizer could be considered as a key factor to control the microbial CFUs and diversity in this Chinese upland red soil. Soil fungi seem to be a more sensitive indicator of soil fertility than soil bacteria. Since the major limitation of molecular methods in soil microbial studies is the lack of discrimination between the living and dead, or active and dormant microorganisms, both culture-dependent and culture-independent methods should be used to appropriately characterize soil microbial diversity.

Effects of Organic Fertilization and Cover Crops on an Organic Pepper System

With the continuing 20% growth rate in the organic industry, organic vegetable crop production has increased to 98,525 acres in the United States. The requirement for certified organic vegetable producers to implement a soil-building plan has led to the development of soil fertility systems based on combinations of organic fertilizers and cover crops. To determine optimal soil fertility combinations, conventional and organic bell pepper (Capsicum annuum) production was evaluated from 2001 to 2003 in Iowa, comparing combinations of two synthetic fertilizers and three compost-based organic fertilizers, and a cover crop treatment of hairy vetch (Vicia villosa) and rye (Secale cereale) in a strip-tilled or fully incorporated cover crop system. Organic pepper growth and yields equaled or surpassed conventional production when nitrogen (N) was provided at 56 or 112 kg·ha−1 from compost-based organic fertilizer. Soil analysis revealed higher N in plots where cover crops were tilled compared with strip-tilled plots, leading to recommendations for sidedressing N in strip-tilled organic pepper production. Increased incidence of disease was also detected in strip-tilled plots. Postharvest weight loss after 6 weeks in storage was similar in organic and conventional peppers. The addition of calcium and sulfur products in conventional or organic fertilizer regimes did not increase pepper production or postharvest storage potential. Despite application challenges, cover crops will remain as critical components of the organic farm plan for their soil-building benefits, but supplementation with approved N sources may be required for optimal pepper production. Organic growers should conduct their own tests of organic-compliant soil amendments to determine cost effectiveness and value for their site before large-scale application.