Long-term Application Of Chemical Fertilizers Research Articles

Responses of denitrifying functional gene abundance to long-term fertilization regimes in an upland Ultisol

Fertilization affects soil nitrogen cycling and nitrous oxide (N2O) emissions, which are mainly driven by microbes. A 32-year field experiment was conducted to investigate the effects of chemical fertilizers and their combination with organic materials on the abundance of denitrifying functional genes (nirS, nirK, nosZ I and nosZ II) in Ultisol. The treatments comprised no fertilizer (CK), chemical fertilizer, chemical fertilizer+peanut straw, chemical fertilizer+rice straw, chemical fertilizer+radish and chemical fertilizer+pig manure. Compared with the single chemical fertilizer treatment, soil pH and organic carbon content increased in the chemical fertilizer plus organic material treatments, with chemical fertilizer+pig manure having the strongest effect. Long-term fertilization did not affect the abundance of nirK gene, but significantly altered the nirS gene abundance. Compared to CK, long-term chemical fertilizer application increased the abundance of nirS gene by 426%. However, partial replacement of chemical fertilizer by organic materials decreased the abundance of nirS gene. The abundance of nosZ I gene was one order of magnitude higher than that of nosZ II, indicating the domination of nosZ I in the acidic Ultisol. Long-term fertilization did not affect the abundance of nosZ II, whereas chemical fertilizer+pig manure increased the abundance of nosZ I by 138%. Results of stepwise regression analysis showed that available phosphorus content was the primary factor regulating the abundance of nosZ I gene, whereas the abundance of the nosZ II gene was mainly regulated by nitrate content. Moreover, the lowest (nirS+nirK)/(nosZ I+nosZ II) value in the chemical fertilizer+pig manure treatment indicated that long-term manure application might reduce N2O emission potential in Ultisols.

Carbon Mineralization and Inorganic Nitrogen Pools under Terminalia chebula Retz.-Based Agroforestry System in Himalayan Foothills, India

Abstract Soil organic matter is major terrestrial pool for soil organic carbon (C) and nitrogen (N), and their decomposition is sensitive to vegetation and climate change. Integrated nutrient management (INM) deals with the combined application of chemical fertilizers and organic manures for nutritional requirement of crops and avoid the adverse effect of long-term application of chemical fertilizer on crop production and their sustainability. The present study was carried out to investigate the influence of different nutrient sources on soil C mineralization and inorganic N pools in a Terminalia chebula Retz, based on a agroforestry system. The results showed that the highest CO2 evolution was recorded in 100 percent INM and minimum in farmyard manure treatment after 120 days of incubation. Inorganic N was higher under the agroforestry system than under the open system. Among the different nutrient sources, the highest inorganic N was recorded in a 100 percent INM nutrient source and minimal in wheat straw treatment. The yield of turmeric was higher under the T. chebula-based agroforestry system (20.87 t ha–1) than under the open system (19.27 t ha–1). Results suggest that agroforestry systems using the INM approach can enhance C mineralization and inorganic N concentration with improved crop productivity in the Himalayan foothills. Study Implications: Fertilizer has been used since ancient times, and if well managed it can be an asset, promoting sustainable agriculture and increasing crop production, particularly for smallholder farmers in the Himalayan region of India. We compared fertilizer application practices under an agroforestry system in a representative Himalayan region of India. The majority of farmers in the region of the Himalayan foothills having marginal land and they are not able to produce optimum food grains for their requirement. However, their demands are increasing day by day, so to fulfill their demand, they have to adopt agroforestry. Agroforestry may be fulfilling their demand in terms of food, fuel, fodder, and other intangible benefits. Moreover, to increase the production under agroforestry, we have to apply organic and inorganic fertilizer in the soil either as the sole application or as a combination of these fertilizers. The application of these fertilizers will improve the productivity and fertility of land, especially carbon mineralization and inorganic nitrogen. These two soil properties are important to study because these are limiting to land productivity. In addition, efforts to improve integrated nutrient management in the Himalayan region of India would strengthen farmers’ incomes by strengthening land fertility and productivity. The rapid increase in human population over the last century is putting a massive pressure on existing resources, namely soil and water, resulting in environmental degradation in some regions around the world. As productive land becomes scarce, marginalized farmers are pushed into fragile croplands and forest lands unsuitable for modern agriculture which, in turn, is vulnerable, to degradation. If the present trend in population growth persists, pasture and forest lands will be further reduced (Satterthwaite et al. 2010). At this stage, the value of growing trees becomes more significant, and participation in tree planting schemes should be encouraged. However, this option is most feasible when combined with agriculture. As a result, agroforestry is an important management strategy that not only helps to meet the world food requirements but also helps to protect soil from degradation (Ram et al. 2017) and can enhance soil organic matter levels by adding the quantity of above- and below-ground organic matter inputs to soils (Nair et al. 2009, Marone et al. 2017).

Short-Term Effects of Eco-Friendly Fertilizers on a Soil Bacterial Community in the Topsoil and Rhizosphere of an Irrigated Agroecosystem

Fertilizer application to arable soils could be effective for soil nutrients. However, there are many negative effects in croplands with long-term chemical fertilizer application. Whether eco-friendly fertilizer addition could enhance soil quality and soil microbial activity has been investigated before; however, how top- and rhizosphere soil bacterial communities respond to their short-term effects is not well known. Here, we used Illumina MiSeq sequencing to determine the changes of bacterial community structure in both topsoil and rhizoshpere after one month of the addition of three different eco-friendly fertilizers—biochar (B), microbial fertilizer (MF), fertilizer synergist (FS) and selected soil base fertilizer (CK) as a control, in an irrigated agroecosystem of cabbage crop (Brassica oleracea L. var. capitata L.). The results show that three different eco-friendly fertilizers significantly enhanced cabbage growth. The Shannon and Ace indexes of the bacterial community significantly decreased under the FS treatment in both soils, but the total abundance of bacteria was maximal under the FS treatment in the topsoil and the MF treatment in the rhizosphere. The addition of the three fertilizers led to significant differences in the relative abundance of bacteria community at the phylum level, such as Proteobacteria, Acidobacteria, Rokubacteria and Planctomycetes in the topsoil, and Chloroflexi, Actinobacteria, Firmicutes and Rokubacteria in the rhizosphere. The same phylum showed the inconsistent changes under different fertilizer treatments in both topsoil and rhizosphere. The dominant genera, i.e., Nitrosospira and Massilia in the topsoil, and Flavobacterium, Nitrosospira and Pseudomonas in the rhizosphere, were much higher under the FS treatment than others. Redundancy analysis showed that total nitrogen and available phosphorus were the key factors that shaped the bacterial community in this ecosystem. These results highlighted that the short-term addition of eco-friendly fertilizer had an improvement effect on the quality of both topsoil and rhizosphere in croplands with long-term chemical fertilizer application.

Soil Chemical and Microbiological Properties Are Changed by Long-Term Chemical Fertilizers That Limit Ecosystem Functioning.

Although the effects of fertilization and microbiota on plant growth have been widely studied, our understanding of the chemical fertilizers to alter soil chemical and microbiological properties in woody plants is still limited. The aim of the present study is to investigate the impact of long-term application of chemical fertilizers on chemical and microbiological properties of root-associated soils of walnut trees. The results show that soil organic matter (OM), pHkcl, total nitrogen (TN), nitrate-nitrogen (NO3−), and total phosphorus (TP) contents were significantly higher in non-fertilized soil than after chemical fertilization. The long-term fertilization led to excessive ammonium-nitrogen (NH4+) and available phosphorus (AP) residues in the cultivated soil, among which NH4+ resulted in soil acidification and changes in bacterial community structure, while AP reduced fungal diversity. The naturally grown walnut trees led to an enrichment in beneficial bacteria such as Burkholderia, Nitrospira, Pseudomonas, and Candidatus_Solibacter, as well as fungi, including Trichoderma, Lophiostoma, Phomopsis, Ilyonectria, Purpureocillium, Cylindrocladiella, Hyalorbilia, Chaetomium, and Trichoglossum. The presence of these bacterial and fungal genera that have been associated with nutrient mobilization and plant growth was likely related to the higher soil OM, TN, NO3−, and TP contents in the non-fertilized plots. These findings highlight that reduced chemical fertilizers and organic cultivation with beneficial microbiota could be used to improve economic efficiency and benefit the environment in sustainable agriculture.

High manure load reduces bacterial diversity and network complexity in a paddy soil under crop rotations

Long-term application of chemical fertilizers causes soil degradation and nitrogen (N) loss, but these effects could be alleviated by organic fertilizers. In addition, crop rotation is a feasible practice to increase soil fertility, soil quality and crop yields comparing with monocultural cropping patterns. However, questions remain concerning how the soil microbiome responds to different manure application rates under crop rotations. Here, we collected soil samples from a rice-rape system to investigate the response of the soil microbiome to nine years of pig manure application at different rates (CK: 0 kg ha-1, M1: 1930 kg ha-1, M2: 3860 kg ha-1 and M3: 5790 kg ha-1). Our results revealed that the bacterial α-diversity (Chao1 and Shannon index) in the rape season increased first and then decreased with increasing manure application rates, and a high manure load tended to decrease the bacterial α-diversity in the rice season. Long-term manure application enriched some copiotrophic bacteria, such as Proteobacteria and Actinobacteria, while it decreased the relative abundance of Nitrospirae. Redundancy analysis (RDA) and the Mantel test indicated that soil pH, TC, TN, AP, C/P and N/P ratios were the main factors influencing bacterial communities. Moreover, network analysis showed that a low manure application rate shaped a complexly connected and stable bacterial community, while higher manure application rate decreased the stability of the bacterial network. These findings improve our understanding of bacterial responses to longterm manure application under crop rotations and their relationships with soil factors, especially in the context of increasing fertilizer inputs.

Effects of Long-Term Fertilization on Different Nitrogen Forms in Paddy along Soil Depth Gradient

The combined application of organic fertilizer and chemical fertilizer is an effective measure to increase nutrient content of soil plough layer, which must have a profound impact on the deep soil nutrients, especially the contents of nitrogen forms. The purpose of this study was to explore the characteristics of soil nitrogen forms in plough layer and along depth gradient in different fertilization treatments, so as to evaluate the soil quality in spatial dimension, further providing a theoretical basis for scientific fertilization and improvement of paddy soil fertility. Here, a 34-year field experiment was conducted with three treatments: without any fertilizer (CK), pure chemical fertilizer (NPK) and chemical fertilizer combined with organic fertilizer (NPKM). We analyzed the content of nitrogen forms in 0 - 100 cm soil depth and their ratios to total nitrogen (TN), and discussed the correlation between nitrogen forms contents and pH, CEC. Results showed that, compared with CK, both NPK and NPKM significantly increased the contents of nitrogen forms in topsoil (soil layer of 0 - 20 cm), especially nitrate nitrogen (NO3--N) content increased by 70% (NPK) and 111% (NPKM), respectively. Although the contents of different nitrogen forms decreased gradually along soil depth gradient, NPKS slowed down the decline rate of TN and alkali-hydrolysable nitrogen (AN) in 0 - 60 cm soil layer, compared to CK. Compared to NPK, NPKM significantly increased the NO3--N/TN ratio in 0 - 20 cm soil layer, but also decreased the content of -N in 20 - 40 cm, which was beneficial to reduce the risk of nitrogen leaching caused by nitrate leaching into deep layer. The increase of soil pH in NPKM treatment obviously alleviated the problem of soil acidification caused by long-term application of chemical fertilizer. Correlation analysis showed that there was a significant positive correlation between soil nitrogen forms and cation exchange capacity (CEC), but no significant correlation with soil pH. In conclusion, NPKM ensured the nutrients of soil plough layer (0 - 20 cm), also reduced the risk of nitrogen infiltration and nitrogen loss, thus ensuring the fertility of soil profile.

Impact of Application of Biochar-Based Fertilizer on the Content of Phosphorus and Potassium in Soil

The application of chemical fertilizer can increase crop yield, but at the same time, it brings huge environmental pressure. Long-term application of chemical fertilizers resulted in deterioration of soil properties, excessive nitrate content in groundwater and increased emissions of greenhouse gases. The object of this study was to investigate application of biochar-based fertilizer (BBF) on the content of phosphorus and potassium in soil. An in-situ field experiment was conducted over 6 years in plain at Shenyang city in China. The experimental design involved five treatment, no fertilizer (CK), low levels of biochar (C15), high levels of biochar (C50), Chemical fertilization (NPK) and biochar-based fertilizer (BBF), with five three replicates of each treatment. Three (CK, NPK, BBF) was selected to research for the phosphorus and potassium in soil. After continuous application, the total phosphorus and potassium content was not affected by different additive. The content of available phosphorus in soil was increased by 1.19 and 1.42 times under chemical fertilizer and under BBF, respectively. The same phenomenon was also observed on available potassium. BBF can significantly improve the content of available phosphorus and potassium in soil, and the effect is better than applying chemical fertilizer. The peanut yield showed a significant increase under BBF than under others.

Effects of long-term fertilization on arbuscular mycorrhizal fungal community in lime concretion black soil.

In agroecosystem, arbuscular mycorrhizal fungi have mutually beneficial symbiosis with roots of many crops. Meanwhile, this special fungal community is also affected by agricultural mana-gements such as fertilization. The objective of this study was to investigate the effects of long-term fertilization managements (no fertilizer, chemical fertilizer, chemical fertilizer combined with straw, chemical fertilizer combined with manure) on arbuscular mycorrhizal fungal community (AM fungal community) in lime concretion black soil, and to identify the indicator species in each fertilization regime. The most dominant arbuscular mycorrhizal fungal phyla in lime concretion black soil were Archaeosporaceae, Diversisporaceae, Gigasporaceae, Claroideoglomeraceae, Glomeraceae and Paraglomeraceae. The genus Paraglomus was strongly and significantly associated with the application of chemical fertilizer and organic fertilizer. Compared with the control, long-term application of chemical fertilizer greatly changed AM fungal community structure and resulted in the decrease of AM fungal diversity, and the addition of wheat straw further decreased the diversity, while the addition of manure could alleviate diversity loss resulted from chemical fertilization. Soil pH and dissolved organic carbon (DOC) were the main factors affecting the changes of AM fungal community. In summary, long-term application of chemical fertilizer combined with different organic materials had different impacts on soil AM fungal community structure and diversity. The combination of chemical fertilizer and manure would be more conducive to the maintenance of AM fungal diversity.

Al(III)-binding properties at the molecular level of soil DOM subjected to long-term manuring

Advanced knowledge of the binding of dissolved organic matter (DOM) with aluminum (Al) ions is essential for understanding the toxicity, mobilization, and fate of Al in acidic soils. In this study, parallel factor analysis (PARAFAC) and two-dimensional correlation spectroscopy (2D-COS) were combined to characterize the Al(III)-binding properties of DOM extracted from farmland topsoil (0–20 cm) subjected to long-term application of chemical fertilizers (CF) or manure (M). The total Al concentration of solid soil in the M treatment (7.57%) was lower than that in the CF treatment (8.56%). In contrast, the organic-complexed Al concentration of the aqueous DOM extract in the M treatment (79 μmol/L) was dramatically higher than that in the CF treatment (0.9 μmol/L). Compared with CF treatment, PARAFAC-derived components in soil DOM from the M treatment had stronger Al(III)-binding affinities (log KM value), suggesting that soil DOM from long-term manuring has stronger potential to mobilize Al in acidic soils than that from chemical fertilizer applications. Fourier transform infrared (FTIR) spectroscopy coupled with 2D-COS revealed that soil DOM from the M treatment exhibited more Al(III)-binding sites than that from the CF treatment. In addition, aliphatic –OH groups showed the fastest response to Al(III) binding. These results provide a more detailed theoretical basis, at the molecular level, of the interaction mechanism of Al(III) with soil DOM, which is helpful for a deeper understanding of DOM-influenced biogeochemical cycling in farmland subjected to long-term manuring.

Influence of long-term fertilization on soil physicochemical properties in a brown soil

This study aims to explore the influence on soil physicochemical properties under a 38-y long-term fertilization in a brown soil. Soil samples (0-20 cm)were taken from the six treatments of the long-term fertilization trial in October 2016:no fertilizer (CK), N1(mineral nitrogen fertilizer), N1P (mineral nitrogen and phosphate fertilizer), N1PK (mineral nitrogen, phosphate and potassic fertilizer), pig manure (M2), M2N1P (pig manure, mineral nitrogen and phosphate fertilizer).The results showed thatthe long-term application of chemical fertilizers reduced soil pH value, while the application of organic fertilizers increased pH value. Fertilization significantly increased the content of AHN, TN and SOM. Compared with the CK treatment and chemical fertilizer treatments, organic fertilizer treatments significantly increased the content of AP and TP. The content of AK and TK were no significant difference in different treatment.

Effects of long-term fertilization on soil gross N transformation rates and their implications

Application of fertilizer has been found to significantly affect soil N cycling. However, a comprehensive understanding of the effects of long-term fertilization on soil gross N transformation rates is still lacking. We compiled data of observations from 10 long-term fertilization experiments and conducted a meta-analysis of the effects of long-term fertilization on soil gross N transformation rates. The results showed that if chemical fertilizers of N, P and K were applied in balance, soil pH decreased very slightly. There was a significantly positive effect of long-term fertilization, either chemical or organic fertilizers or their combinations, on gross N mineralization rate compared to the control treatment (the mean effect size ranged from 1.21 to 1.25 at 95% confidence intervals (CI) with a mean of 1.23), mainly due to the increasing soil total N content. The long-term application of organic fertilizer alone and combining organic and chemical fertilizer could increase the mineralization-immobilization turnover, thus enhance available N for plant while reduce N losses potential compared to the control treatment. However, long-term chemical fertilizer application did not significantly affect the gross NH4+ immobilization rate, but accelerated gross nitrification rate (1.19; 95% CI: 1.08 to 1.31). Thus, long-term chemical fertilizer alone would probably induce higher N losses potential through NO3− leaching and runoff than organic fertilizer application compared to the control treatment. Therefore, in the view of the effects of long-term fertilization on gross N transformation rates, it also supports that organic fertilizer alone or combination of organic and chemical fertilizer could not only improve crop yield, but also increase soil fertility and reduce the N losses potential.

Differences of C sequestration in functional groups of soil humic acid under long term application of manure and chemical fertilizers in North China

The differences of molecular characteristic of humic acid (HA) under long-term application of chemical fertilizer and manure for 34 years were determined by 13C cross polarization magic angle spinning nuclear magnetic resonance (13C CPMAS NMR) spectroscopy in order to investigate the carbon (C) sequestration in soils. The results showed that the relative content of alkyl C increased in manure treatments, compared to control and chemical fertilizer treatments. There were positive correlations between alkyl C and hydrogen to carbon (H/C) ratio (R2=0.84, P<0.01), alkyl C and amounts of HA (R2=0.57, P<0.01) as well as alkyl C and E4/E6 ratio (R2=0.55, P<0.01). Conversely, negative correlations were found between aromatic C and alkyl C (R2=0.76, P=0.01), H/C ratio and aromaticity (R2=0.37, P=0.04), aromaticity and amounts of HA (R2=0.71, P<0.01) as well as aromaticity and E4/E6 ratio (R2=0.65, P<0.01). Compared to control treatment, the amorphous C/crystalline C ratio increased for 0.02–0.14 and 0.30–0.78 in chemical fertilizer treatments and manure treatments, separately. Moreover, the short-chain (CH2)n/Long-chain (CH2)n ratio increased for 0.03–0.37 and 0.03–0.18 in chemical fertilizer treatments and manure treatments, separately.These findings suggest that application of manure favours alkyl C sequestration in HA and tends to be more closely linked to amorphous C than crystalline C, while incorporates less short-chain (CH2)n, compared to chemical fertilizer treatments. Moreover, the E4/E6 ratio of HA increased with more alkyl C.

Long-term (≥20 years) application of fertilizers and straw return enhances soil carbon storage: a meta-analysis

Increasing soil carbon (C) storage is crucial to addressing climate change and ensuring food security. The C sequestration potential of the world’s cropland soil is 0.4–0.8 Pg soil C year−1, which may be achieved through the adoption of recommended management practices (RMPs), including fertilizer management. This study aimed to quantitatively evaluate the influence of long-term application of different fertilizers and straw retention on soil organic carbon (SOC) storage, to compare the calculated response ratios with Intergovernmental Panel on Climate Change (IPCC)-recommended default relative stock change factors, and to propose recommendations for enhancing SOC sequestration. The meta-analysis indicated that the long-term application of chemical fertilizers (CF), organic fertilizers (OF), combined chemical and organic fertilizers (CFOF), and straw return (SR) significantly enhanced the SOC storage. Response ratios varied significantly (p < 0.05) across different fertilization measures and climatic zones, and was sensitive to the initial SOC content. The mean response ratio was 0.94 for no fertilizer (NF), 1.08 for CF, 1.48 for OF, 1.38 for CFOF, and 1.28 for SR. When IPCC default values for response ratios were applied, SOC storage with OF and CFOF treatments in warm temperate regions with a dry climate was underestimated by 26%, and in the cool temperate region with a moist climate was overestimated by 25% (p < 0.05). Analysis showed that sustained application of organic fertilizers and straw return could be a beneficial measures to mitigate climate change and ensure food security in China. Our findings highlight the importance of deriving SOC stock change factors for a detailed classification of cropland by fertilizer management, climate, and soil types in order to more accurately reflect the effects of policy measures.

Effects of fertilizing regime and planting age on soil calcium decline in Luochuan apple orchards

This study was conducted to assess the effects of fertilizing regime and orchard planting age on soil calcium contents and stocks in the apple orchards on the Loess Plateau. The apple orchards in Luochuan County, one of the best regions for apple plantation in the world, were selec-ted in this study. The contents of calcium carbonate,water-soluble calcium and exchangeable cal-cium at 0-100 cm soil layer under different fertilizing regimes and various planting ages were mea-sured, their stocks were calculated and their variation features were analyzed. The results showed that soil in the apple orchards in the study region was characterized by the decline in calcium contents. The decline was more serious in apple orchards with long-term application of chemical fertili-zer than in those with combined application of chemical fertilizer and farmyard manure. The average contents of calcium carbonate, water-soluble calcium and exchangeable calcium at 0-100 cm soil layer in apple orchards with long-term application of chemical fertilizer decreased by 38.8%, 25.4% and 5.6% respectively than those in the apple orchards with long-term application of both chemical fertilizer and farmyard manure. The stocks of calcium carbonate, water-soluble calcium and exchangeable calcium decreased by 36.4%, 26.0% and 4.3%, respectively. The decline of soil cal-cium was aggravated with the increase of orchard planting age. The contents of calcium carbonate, water-soluble calcium and exchangeable calcium at 0-100 cm soil layer in orchards of more than 25 years of planting age decreased by 48.8%, 69.4% and 39.5% respectively, compared with orchards of less than 10 years of planting age, and the stocks decreased by 40.8%, 64.1% and 33.0%, respectively. These results indicated that either long-term application of chemical fertilizer or long-term plantation of apple trees obviously depleted soil calcium carbonate, water-soluble calcium and exchangeable calcium. Therefore, it was recommended that application of chemical fertilizer and farmyard manure should be combined to mitigate soil calcium decline, and calcium management should be strengthened in apple orchards of more than 25 years of planting age. The fertilizing regime was a driving factor of soil calcium decline which had a significant temporal (orchard planting age) and spatial (soil depth) effect.

Effects of adjacent land-use types on the distribution of soil organic carbon stocks in the montane area of central Taiwan.

BackgroundSoil organic carbon (SOC) stocks can be altered through reforestation and cropping. We estimated the effects of land use on SOC stocks after natural deciduous forests replaced by crops and coniferous plantations by examining the vertical distribution of SOC stocks at different depth intervals in an adjacent Oolong tea (Camellia sinensis L.) plantation, Moso bamboo (Phyllostachys pubescens) forest, Japanese cedar (Cryptomeria japonica) forest, and Taiwania (Taiwania cryptomerioides) forest in central Taiwan. The main soil characteristics, soil nitrogen (N) content, and soil carbon to nitrogen (C/N) ratio were also determined.ResultsDifferent land uses resulted in significantly higher bulk density, lower cation exchange capacity, SOC, soil N, soil C/N ratio, and SOC stocks in croplands compared to forestlands. Due to the long-term application of chemical fertilizers, a significantly lower soil pH was found in the tea plantation. Croplands had a lower soil C/N ratio because of less C input into the soil and a higher mineralization rate of organic carbon during cultivation. Similar SOC stocks were found in Taiwania and Japanese cedar forests (148.5 and 151.8 Mg C ha−1, respectively), while the tea plantation had comparable SOC stocks to the bamboo forest (101.8 and 100.5 Mg C ha−1, respectively). Over 40% of SOC stocks was stored in croplands and over 56% was stored in forestland within the upper 10 cm of soil.ConclusionsConiferous plantations can contribute to a higher SOC stock than croplands, and a significant difference can be found in the top 0–5 cm of soil.Electronic supplementary materialThe online version of this article (doi:10.1186/s40529-016-0147-5) contains supplementary material, which is available to authorized users.

Application of Bioorganic Fertilizer Significantly Increased Apple Yields and Shaped Bacterial Community Structure in Orchard Soil.

Application of bioorganic fertilizers has been reported to improve crop yields and change soil bacterial community structure; however, little work has been done in apple orchard soils where the biological properties of the soils are being degraded due to long-term application of chemical fertilizers. In this study, we used Illumina-based sequencing approach to characterize the bacterial community in the 0-60-cm soil profile under different fertilizer regimes in the Loess Plateau. The experiment includes three treatments: (1) control without fertilization (CK); (2) application of chemical fertilizer (CF); and (3) application of bioorganic fertilizer and organic-inorganic mixed fertilizer (BOF). The results showed that the treatment BOF increased the apple yields by 114 and 67% compared to the CK and CF treatments, respectively. The treatment BOF also increased the soil organic matter (SOM) by 22 and 16% compared to the CK and CF treatments, respectively. The Illumina-based sequencing showed that Acidobacteria and Proteobacteria were the predominant phyla and Alphaproteobacteria and Gammaproteobacteria were the most abundant classes in the soil profile. The bacterial richness for ACE was increased after the addition of BOF. Compared to CK and CF treatments, BOF-treated soil revealed higher abundance of Proteobacteria, Alphaproteobacteria and Gammaproteobacteria, Rhizobiales, and Xanthomonadales while Acidobacteria, Gp7, Gp17, and Sphaerobacter were found in lower abundance throughout the soil profile. Bacterial community structure varied with soil depth under different fertilizer treatments, e.g., the bacterial richness, diversity, and the relative abundance of Verruccomicrobia, Candidatus Brocadiales, and Skermanella were decreased with the soil depth in all three treatments. Permutational multivariate analysis showed that the fertilizer regime was the major factor than soil depth in the variations of the bacterial community composition. Two groups, Lysobacter and Rhodospirillaceae, were found to be the significantly increased by the BOF addition and the genus Lysobacter may identify members of this group effective in biological control-based plant disease management and the members of family Rhodospirillaceae had an important role in fixing molecular nitrogen. These results strengthen the understanding of responses to the BOF and possible interactions within bacterial communities in soil that can be associated with disease suppression and the accumulation of carbon and nitrogen. The increase of apple yields after the application of BOF might be attributed to the fact that the application of BOF increased SOM, and soil total nitrogen, and changed the bacterial community by enriching Rhodospirillaceae, Alphaprotreobateria, and Proteobacteria.

Effect of Long-term Application of Chemical Fertilizer on the Quality of Summer Maize

The study on the effect of fertilization on the quality of maize grain was conducted based on continue application of fertilizer for 26 and 36 years in gleyic cambisols. The amounts of protein, starch, fat and amino acid were determined and the amino acid was analyzed by cluster analysis. The results showed: Long-term fertilization 26 years showed that N2K and N2P processing protein content as high as 9.01, 9.01%, lowest comparing CK treatment is 5.52%; all fertilizer treatments reduced the summer maize starch content, including N2PK deal with relatively high starch content is 57.55%; N2K processing crude fat content as high as 5.95%; N2P processing total amino acids and essential amino acid content is the highest, 8.13 and 3.22%, respectively. Long-term fertilization 36 years (2013) summer maize grain each nutrition indicators in line with 26 years change rule.

Dynamics of iron under long-term application of chemical fertilizers and amendments on maize-wheat cropping sequence

ABSTRACTIron (Fe) is one of the essential micronutrient plays a crucial role in redox systems in cells and in various enzyme. The Fe-deficient plants have lower redox reaction and enzymatic activity. Intensive chemical fertilizer resulted in depletions of micronutrients especially Fe from the soil. To understand the dynamics of Fe under long-term fertilizer experiment the present study was initiated during 1972 at experimental farm of College of Agriculture CSK HPKV, Palampur in randomized block design with eleven treatments replicated thrice. The soil of the experimental area was silty loam, acidic in reaction and taxonomically classified as “Typic Hapludalfs.” Surface (0–20 cm) and subsurface (20–40 cm) soil samples collected after the harvest of maize (Kharif, 2008). The continuous use of chemical fertilizers and amendments for the last 36 years in maize-wheat system in an acid Alfisol brought out marked depletion in the pools of Fe as compared to buffer plots. All the pools of Fe were noticeably higher in farmyard manure (FYM) amended plots compared to zero-fertilized plots. Although, residual fraction was found to be the most dominant fraction but organically bound and exchangeable forms were found to play major role in the nutrient supply and crop productivity and nutrients’ uptake. Highest productivity of maize (2008) and wheat (2008–2009) was recorded under 100% nitrogen, phosphorus and potassium (NPK) + FYM treatment. FYM and lime treatments resulted in significantly higher uptake of all the nutrients by both the crops compared to other treatments. Organically bound fraction was found to have highest significant and positive correlation with yield and nutrient uptake of maize and wheat crops. Further, regression analysis studies too revealed that organic form was the most important pool contributing towards the variation in the above parameters. While, exchangeable and organically bound forms contributed significantly towards diethylene triamine pentaacetic acid (DTPA)-extractable Fe.

Spectral Exploration of Calcium Accumulation in Organic Matter in Gray Desert Soil from Northwest China.

Little attention has been paid to the accumulation of soil organic matter (SOM) in the fringes of the mid-latitude desert. In this paper, soil samples from a long-term field experiment conducted from 1990 to 2013 at a research station in Urumqi, China by different fertilizer treatments, were used to determine soil properties and soil dissolved organic matter (DOM) by chemical analysis, fluorescence excitation emission matrix (EEM) spectroscopy, and high resolution-transmission electron microscopy (HR-TEM). The binding features of DOM under the addition of Ca2+ were analyzed using a two-dimensional (2D) Fourier transform infrared (FTIR) spectrometer further to explore the response of the DOM to increasing concentrations of Ca2+. Long-term application of chemical fertilizers and goat manure increased soil organic carbon (SOC) by 1.34- and 1.86-fold, respectively, relative to the non-fertilized control (8.95g.kg-1). Compared with the control, application of chemical fertilizers and manure significantly increased the concentrations of Ca, Mg, Si, humic and fulvic acid-like substances in DOM but decreased the amounts of trivalent metals (Al and Fe) and protein-like substances. Although crystalline Al/Fe nanoparticles and amorphous or short-range-order Si/Al nanoparticles existed in all DOM samples, crystalline Ca/Si nanoparticles were predominant in the samples treated with goat manure. Although organic matter and Si-O-containing nanoparticles were involved in the binding of Ca2+ to DOM, application of chemical fertilizers weakened Ca2+ association with components of the amide II group (1510 cm-1) and Si-O linkage (1080 cm-1), whereas application of goat manure enhanced the affinity of Ca2+ for Si-O linkage. Our results suggested that the enrichment of Ca in gray desert soil possibly helps accumulate SOM by forming crystalline Ca/Si nanoparticles in addition to Ca2+ and organic matter complexes.

Effects of long-term application of chemical and organic fertilizers on the abundance of microbial communities involved in the nitrogen cycle

Long-term agricultural fertilization significantly affects nitrogen cycling in soils. However, there is little information about the response of different functional genes involved in the nitrogen cycle to chemical and organic fertilization, and the key factor influencing the community abundance. We investigated the influence of long-term application of chemical fertilizer (NPK) and combined with wheat straw or livestock manures on the abundance of six nitrogen cycle genes (nifH, archaeal and bacterial amoA, nirS, nirK and nosZ) by quantitative PCR. Compared with non-fertilization treatment, long-term application of NPK fertilizers significantly increased the abundance of nirK, nosZ and bacterial amoA genes but decreased archaeal amoA gene abundance, with no significant effect on the abundance of nifH and nirS genes. Compared with NPK treatment, the application of NPK+organic manure increased the abundance of all the nitrogen-cycling genes while the application of NPK+wheat straw had little effect. The abundance of amoA genes contributed the most to the variations in the abundance of the nitrogen cycling community between different fertilization strategies. Soil available P and total N were the most important factors influencing the abundance of microbial communities involved in the nitrogen cycle. These results indicated that, under the application of chemical fertilizers, the addition of livestock manures had much stronger effects on the abundance of nitrogen cycle genes than the addition of wheat straw, and bacterial and archaeal amoA genes were more sensitive to fertilization than other functional genes.