N And P Research Articles

Characteristics of the Soil Microbial Community Structure under Long-Term Chemical Fertilizer Application in Yellow Soil Paddy Fields

To compare the differences in the soil microbial community structure in yellow soil paddy fields after the long-term application of chemical fertilizer, the role and mechanism of chemical fertilizer in maintaining soil microbial diversity were analyzed, and a theoretical basis for fertilization management in farmlands was provided. In this study, long-term experiments were conducted at the Scientific Observation and Experimental Station of the Arable Land Conservation and Agricultural Environment (Guizhou), Ministry of Agriculture and Rural Affairs. Soil samples were collected from five treatments: fertilizer N, P, and K (NPK); fertilizer P and K (PK); fertilizer N and K (NK); fertilizer N and P (NP); and no fertilizer (CK). High-throughput sequencing technology was used to analyze the microbial composition and diversity of the colonies, and the influencing factors are discussed. An analysis of the soil bacterial α diversity indices under the different fertilization treatments revealed that the long-term application of NPK fertilizers had less of an effect on the soil bacterial α diversity indices than did the CK. The long-term application of chemical fertilizers significantly reduced the soil bacterial Chao1, Shannon, and Simpson indices, while there was no significant difference in the bacterial Pielou e index among the treatments. The long-term application of chemical fertilizers significantly increased the soil fungal Chao1 index, but the effects on the other indices were not significant (p < 0.05). An analysis of the bacterial and fungal species under different fertilization treatments showed found that compared with CK, the long-term application of chemical fertilizer increased the relative abundance of Proteobacteria to varying degrees while reducing the relative abundance of Chloroflexi. The impact of other phyla was relatively small, and the difference in the relative abundance of fungi was not significant (p < 0.05). Principal component analysis revealed that, at the genus level, the bacterial and fungal community structures in the CK and NK treatments were relatively independent, while those in the NPK, PK, and NP treatments were similar. Random forest analysis revealed that OM, TP, and TK are the dominant factors that affect soil bacteria α diversity. The dominant factors affecting fungi α diversity are pH, OM, and AK. Redundancy analysis indicated that AK and TP were the main factors affecting bacterial community structure, while AP, AK, and pH were the main factors affecting fungal community structure. The conclusion drawn from this study is that the long-term application of nitrogen, phosphorus, and potassium fertilizer; phosphorus and potassium fertilizer; and nitrogen and phosphorus fertilizer can improve soil fertility, alter the soil environment, enhance microbial diversity, and improve the microbial community structure in yellow soil paddy fields, promoting soil ecosystem stability and health.

Divergent responses of rhizosphere soil phosphorus fractions and biological features of Salix psammophila to fertilization strategies under cadmium contamination

Soil oligotrophy in areas heavily contaminated with heavy metals poses a significant challenge to vegetation establishment and phytoremediation processes. Phosphorus (P) cycling plays a critical role in global biogeochemical cycles, but there is limited understanding of its response to varying fertilization strategies and its correlation with phytoremediation effectiveness. This study primarily investigated the effects of various fertilization strategies, including nitrogen (N, 300 mg·kg−1), P (100 mg·kg−1), NP (combined N and P at 300 mg·kg−1 and 100 mg·kg−1, respectively), and HP (high P, 300 mg·kg−1) application, on rhizosphere soil P fractions and P-solubilizing microbial community (harboring phoD and phoC genes, respectively) of Salix psammophila under cadmium contamination. Application of NP significantly enhanced plant growth and cadmium accumulation, whereas HP inhibited cadmium bioaccumulation but promoted its translocation. Compared to untreated soil, N application promoted P cycling, leading to increases of 141.9 %, 60.4 %, and 10.3 % in Resin-Pi, diluted HCl-Pi, and conc.HCl-Pi, respectively. P application decreased organic phosphorus (Po) fractions by 24.4 % - 225.8 %, but N incorporation mitigated the declining trend in Po and augmented alkaline phosphatase activity. Fertilization strategies significantly regulated phoC- or phoD-harboring bacterial community structure, but their differential nutrient demands resulted in distinct responses. The phoD-harboring bacteria exhibited higher diversity and network complexity, with numerous biomarkers and fertilizer-sensitive OTUs discovered across treatments. Structural equation modeling (SEM) analysis indicated that phytoremediation efficiency was directly affected by Pi fractions, and phoD-harboring bacteria exhibited stronger associations with Pi fractions than phoC-harboring bacteria. In conclusion, our results reveal potential pathways through which fertilization strategies influence phytoremediation by affecting the structure of P-solubilizing microbial community. Furthermore, our study emphasizes the importance of combined N and P application in promoting Cd accumulation in plants, with high P levels appearing as an ideal fertilization strategy for phytoremediation targeting the harvest of aboveground biomass.

Contrasting effects of nitrogen and phosphorus additions on nitrogen competition between coniferous and broadleaf seedlings

Nitrogen (N) is a major element limiting plant growth and metabolism. Nitrogen addition can influence plant growth, N uptake, and species interactions, while phosphorus (P) addition may affect N acquisition. However, knowledge of how nutrient availability influences N uptake and species interactions remains limited and controversial. Here, pot experiments were conducted for 14 months, in which conifers (Pinus massoniana and Pinus elliottii) and broadleaved trees (Michelia maudiae and Schima superba) were planted in monoculture or mixture, and provided additional N and P in a full-factorial design. Nitrogen addition increased the biomass, but P addition did not significantly affect the biomass of the four subtropical species. Combined N and P (NP) addition had no additive effect on plant biomass over N addition. Total plant biomass was significantly positively correlated to root traits (branching intensity and root tissue density) and leaf traits (net photosynthetic rate, stomatal conductance, and transpiration rate), but negatively correlated to root diameter in response to nutrient addition. Plant uptake rates of NH4+ or NO3− were not altered by N addition, but P or NP additions decreased NH4+ uptake rates and increased NO3− uptake rates. Neighboring conifers significantly inhibited NH4+ and NO3− uptake rates of the two broadleaf species, but neighboring broadleaves had no effects on the N uptake rates of pine species. The effects of nutrient additions on interspecific interactions differed among species. Nitrogen addition altered the interaction of P. elliottii and M. maudiae from neutral to competition, while P addition altered the interaction of P. massoniana and M. maudiae from neutral to favorable effects. Increasing nutrient availability switched the direction of interspecific interaction in favor of pines. This study provides insights into forest management for productivity improvement and optimizing the selection of broadleaf species regarding differences in soil fertility of subtropical plantations.

Cover crop by irrigation and fertilization improves soil health and maize yield: Establishing a soil health index

Cover crop can reduce the intensity of land use, and improve soil fertility and productivity in multiple-cropping systems. However, only a few studies have comprehensively evaluated soil health after cover crops in terms of management goal and soil multi-functionality. In this study, different minimum data set (MDS) methods were used to establish a soil health index (SQI) model to evaluate soil health of the winter smooth vetch-summer maize cropping system in southwest China. We analyzed thirty-five soil parameters (representing soil physical, chemical and biological properties) connected with the soil functions as potential soil health indicators in the phase of smooth vetch and maize under six management treatments (CK (control), N (N fertilizer), P (P fertilizer), NP (N and P fertilizer), NPW (N and P fertilizer + irrigation), CF (fallow)). Those managements were set in the smooth vetch phase (as a cover crop). The MDS using correlation analysis (cMDS), principal component analysis (pMDS) and random forest analysis (rMDS) from the total data set (TDS) were selected and then used for SQIs calculation, respectively. Cover crop by different management of irrigation and fertilization affected each soil property in different ways. All three SQIs were significantly correlated with SQI-TDS, validating the SQI models developed by three MDS methods (P < 0.05). Further, the SQI based on rMDS was the most accurate and sensitive, suggesting the RFA-based SQI reflects soil functions more adequately than the CA and PCA-based SQI. Cover crop by the management of fertilization or/and irrigation will not only improve soil health, but also enhance maize yield compared with fallow treatment, especially for NPW treatment. Fertilization treatments (N, P, NP and NPW) had higher soil health index, which was related to the better performance of soil in sustaining biological activity, physical stability and supporting function. In summary, the SQI model developed by the RFA method can provide a practical and robust tool for assessing soil health based on the management goal.

Nitrogen but not phosphorus addition affects symbiotic N2 fixation by legumes in natural and semi-natural grasslands located on four continents

Background and aimsThe amount of nitrogen (N) derived from symbiotic N2 fixation by legumes in grasslands might be affected by anthropogenic N and phosphorus (P) inputs, but the underlying mechanisms are not known.MethodsWe evaluated symbiotic N2 fixation in 17 natural and semi-natural grasslands on four continents that are subjected to the same full-factorial N and P addition experiment, using the 15N natural abundance method.ResultsN as well as combined N and P (NP) addition reduced aboveground legume biomass by 65% and 45%, respectively, compared to the control, whereas P addition had no significant impact. Addition of N and/or P had no significant effect on the symbiotic N2 fixation per unit legume biomass. In consequence, the amount of N fixed annually per grassland area was less than half in the N addition treatments compared to control and P addition, irrespective of whether the dominant legumes were annuals or perennials.ConclusionOur results reveal that N addition mainly impacts symbiotic N2 fixation via reduced biomass of legumes rather than changes in N2 fixation per unit legume biomass. The results show that soil N enrichment by anthropogenic activities significantly reduces N2 fixation in grasslands, and these effects cannot be reversed by additional P amendment.

Variation in Soil Denitrification among Fertilization Regimes and Its Microbial Mechanism

A 27-year field experiment with various fertilization regimes was chosen for evaluating how fertilization regimes influence soil denitrification potential (SDP), to determine whether the microbial mechanism of SDP variation varies with fertilization regimes. The results showed that the compost (OM) fertilizer treatment presented the highest SDP followed by half compost plus half chemical fertilizer (NPKOM) treatment. Both SDPs were 3–25 times higher than those of the other treatments, and the SDP was higher in the OM than NPKOM, indicating an increase in SDP with the application of compost. The higher SDPs from OM and NPKOM were closely associated with higher abundances of functional genes, and enrichments of Rubrivivax gelatinosus and Azospirillum sp. TSO28-1, is mainly determined by the organic carbon (SOC), total nitrogen (TN), and dissolved organic carbon (DOC). For the treatments without compost, SDP mainly followed the order of chemical fertilizers of N and P (NP) > chemical fertilizers of N and K (NK) > unfertilized (Nil) > chemical fertilizers of N, P, and K (NPK) > chemical fertilizers of P and K (PK), in which the variations had a close association with different specific microbial species. That is, relative to Nil, the enhanced SDP in NP and NK was coupled with the enrichment of Ideonella sp. NC3L-43b and R. gelatinosus, likely due to their higher NO3 − contents, while the reduced SDP in NPK was linked to the depletions of R. gelatinosus and Azospira sp. NC3H-14, and that in PK to the depletion of R. gelatinosus and Azospirillum sp. TSO28-1, probably as a result of their lower N:P ratios. Microbial mechanisms for SDP differences varied with fertilization regimes, and R. gelatinosus can be regarded as a universal microbial indicator for SDP differences across the fertilization treatments.

Long-term differences in nutrient management under intensive cultivation alter potassium supplying ability of soils

Despite removal of potassium (K) by crops in large quantities, often exceeding that of nitrogen (N), K fertilization has long been neglected compared with N and phosphorus (P) in Indian agriculture leading to mining of soil K. We, therefore, studied the effect of long-term fertilization (with or without K) on K supplying ability of two major soil orders of India, viz. Inceptisol and Vertisol after more than four decades of cultivation. Soil samples (0–15 and 15–30 cm) were collected after the completion of 43 (Inceptisol) or 42 (Vertisol) cropping cycles from on-going long-term experiments located at New Delhi (Inceptisol) and Jabalpur (Vertisol), India, from six treatments, viz. no-fertilization (control), recommended N (N), N and P (NP), N, P and K (NPK), 150% NPK and NPK + farmyard manure (NPK + FYM), along with adjacent uncultivated land. Ammonium acetate extractable K (Kex), non-exchangeable K (NEK), quantity-intensity relationship and K release kinetics along with grain yields and K uptake by crops were studied. The Kex and K-saturation of exchange complex in both soils and NEK in the Inceptisol were the lowest under NP followed by N. Cropping without K input resulted in lower quantity (non-specifically and specifically held K i.e. –ΔK0 and Ks) and intensity (equilibrium activity ratio i.e. AReK) of K in both soils. More negative values of standard free energy of exchange (ΔG0) under cultivation without K in both soils indicated increased affinity of soil solids for K+ owing to K omission. The gap between equilibrium exchangeable K (EK0) and minimum exchangeable K (EKmin) was significantly lower under cropping without K than with K in the Vertisol. Imbalanced fertilization (N or NP) also showed noticeably smaller cumulative K releases and slower rates of replenishment of solution K by solid phase K in both soils. Interestingly, even under cropping with K fertilization at either experimental site, several K supply parameters showed decline compared with adjacent uncultivated soil. Grain yields of wheat and total K uptake by all crops (maize and wheat in Inceptisol; soybean and wheat in Vertisol) showed significant and positive response to K application. The study showed variable effect of long-term intensive cropping with or without K input on the K supplying ability of an Inceptisol and a Vertisol. The findings underlined inadequacy of the existing K fertilizer recommendations, and the need for their refinement to minimize native K mining and sustain K supplying ability of soils.

Na compound fertiliser improves growth performance, drought resistance, and water-saving efficiency of the succulent xerophyte

For Haloxylon ammodendron – a typical succulent xerophyte that accumulates Na+ to resist drought stress– the use of a Na-compound fertiliser (NaCF) at small scales could increase drought resistance. In this study we compared the effects of NaCF, NP (with N and P contents the same as in NaCF), diammonium phosphate (DP), and a control (C) on growth of H. ammodendron in the Alashan Desert regions of China. Results indicated that NaCF significantly increased plant height (PH) by 56, 27 and 12%, main root length (MRL) by 72, 60 and 45%, dry weight (DW) of whole plant by 291, 124 and 89%over the C, NP and DP treatments respectively in the nursery. NaCF also significantly improved drought resistance of H. ammodendron in large-scale desert afforestation, where it increased PH by 4.6 and 1.8 cm plant–1, main root length (MRL) by 4.5 and 4.1 cm plant–1, and DW by 17.9 and 15.9 g plant–1 compared with the C and DP treatments respectively. Furthermore, compared with the seedlings treated with DP in the nursery and in the desert afforestation, seedlings treated with NaCF resulted in water saving potentials of 50 and 33% respectively. These findings indicate that NaCF could be beneficial if widely applied in eco-restoration of the degraded vegetations in desert regions of China.

Impact of forty-seven years of long-term fertilization and liming on soil health, yield of soybean and wheat in an acidic Alfisol

ABSTRACT Fertilization with suitable amendment in acidic soil is crucial to achieve long-term high crop yield without deteriorating soil health in intensive cropping system. We studied the chemical and biological properties of soil, soybean, and wheat yield after 47 years of long-term fertilization in an acidic Alfisol. Treatments were: unfertilized (control); recommended N dose (N); recommended N and P (NP); recommended N, P and K (NPK); NPK + hand weeding (NPK + HW); NPK + 10 Mg ha−1 farmyard manure (NPK + FYM) and NPK + 0.40 Mg ha−1 lime (NPK + lime). Long-term application of NPK + FYM significantly enhanced the soil cation exchange capacity (CEC), organic carbon, available NPK and microbial functions compared to NPK. Application of NPK + lime increased soil pH, dehydrogenase activity (DHA) and bacterial population by 15.7%, 38.8% and 145% respectively, over NPK. Continuous inorganic-P fertilizer application leads to substantial build-up of available-P in soil. Fertilization of FYM/lime with NPK recorded higher crops yield compared to NPK. Soil DHA, bacterial population and CEC were most influencing factors governing grain yield. Overall, long-term application of NPK with FYM/lime improved soil health and crop yield, but rate of inorganic-P input should be curtailed in an Alfisol.

Long-term fertilization and residue return affect soil stoichiometry characteristics and labile soil organic matter fractions

Ecological stoichiometry provides the possibility for linking microbial dynamics with soil carbon (C), nitrogen (N), and phosphorus (P) metabolisms in response to agricultural nutrient management. To determine the roles of fertilization and residue return with respect to ecological stoichiometry, we collected soil samples from a 30-year field experiment on residue return (maize straw) at rates of 0, 2.5, and 5.0 Mg ha−1 in combination with 8 fertilization treatments: no fertilizer (F0), N fertilizer, P fertilizer, potassium (K) fertilizer, N and P (NP) fertilizers, N and K (NK) fertilizers, P and K (PK) fertilizers, and N, P, and K (NPK) fertilizers. We measured soil organic C (SOC), total N and P, microbial biomass C, N, and P, water-soluble organic C and N, KMnO4-oxidizable C (KMnO4-C), and carbon management index (CMI). Compared with the control (F0 treatment without residue return), fertilization and residue return significantly increased the KMnO4-C content and CMI. Furthermore, compared with the control, residue return significantly increased the SOC content. Moreover, the NPK treatment with residue return at 5.0 Mg ha−1 significantly enhanced the C:N, C:P, and N:P ratios in the soil, whereas it significantly decreased the C:N and C:P ratios in soil microbial biomass. Therefore, NPK fertilizer application combined with residue return at 5.0 Mg ha−1 could enhance the SOC content through the stoichiometric plasticity of microorganisms. Residue return and fertilization increased the soil C pools by directly modifying the microbial stoichiometry of the biomass that was C limited.

Variation of soil dissolved organic carbon under long-term different fertilizations and its correlation with maize yields

There have been many studies about the effects of long-term fertilizations on crop yields and soil organic carbon. However, little attention has been paid to the response of soil dissolved organic carbon (DOC) to fertilization practices. The aims of this work were to investigate the variations of the content and the chemical composition of soil DOC under long-term different fertilizations and to evaluate their correlations with maize yields. A long-term fertilization experiment under a double maize cropping system was established in 1986 in acidic Ultisols of southern China. Soil samples were collected in April 2014 from the following ten treatments: (1) CK (non-fertilization), (2) N (only N fertilization), (3) P (only P fertilization), (4) K (only K fertilization), (5) NP (N and P fertilization), (6) NK (N and K fertilization), (7) NPK (N, P, and K fertilization), (8) HNPK (double doses of NPK fertilization amount), (9) OM (only organic manure), and (10) NPKM (NPK fertilization plus organic manure). The soil basic chemical properties including the content of DOC were determined. Then, the chemical composition of soil DOC was assessed through three-dimensional excitation-emission matrix (3DEEM) and parallel factor analysis (PARAFAC). The results showed that long-term application of organic manure significantly increased the content of soil DOC and obviously changed the chemical composition of soil DOC. Based on the 3DEEM and PARAFAC, organic manure treatments (OM, NPKM) had higher proportions of tryptophan-like components and lower proportions of tyrosine-like components as compared with other treatments (CK and inorganic fertilizer treatments). For the fluorescence indices, organic manure treatments showed significantly higher humification index (HIX) and lower biological index (BIX) and McKnight index than other treatments. Aggregated boosted trees analysis revealed that the DOC content explained 24.6% of the total variance in maize yields and ranked first among all tested soil chemical properties. Furthermore, all fluorescence properties of DOC were correlated with maize yields, in which the HIX index was the most important factor. This research demonstrated that not only the content of DOC but also the chemical composition of DOC in acidic Ultisols were significantly correlated to maize yields. It may be an effective way to improve soil quality and productivity by increasing DOC content and HIX index. From the perspective of soil DOC, our results proved again that application of organic manure could be the most suitable fertilization practice in acidic Ultisols of southern China.

Linkages between nutrient ratio and the microbial community in rhizosphere soil following fertilizer management

To unravel the linkages between ecological ratios (C:N:P) and the microbial community in rhizosphere soil in response to fertilizer management, soil samples were collected from a proso millet (Panicum miliaceum L.) field under different fertilizer management systems, including nitrogen fertilizer (NF), phosphorus fertilizer (PF), combined N and P (NP) fertilizer, and organic fertilizer (OF); no fertilizer (CK) was used as a control. Furthermore, 16S rRNA and ITS gene sequencing were applied to represent the bacterial and fungal diversity in the soil. Moreover, the elemental properties, including the carbon (C), nitrogen (N), and phosphorus (P) contents, in the microbial biomass and rhizosphere soil were evaluated. The results showed that the C, N, and P contents and microbial biomass (MBC, MBN and MBP, respectively) in the rhizosphere soil were augmented following fertilizer management. Increases in the alpha diversity indices (Shannon and Chao 1) of soil bacteria and fungi were observed in response to the fertilizers, and the responses were more closely related to the soil C:N and N:P ratios than to the C:P ratio. Additionally, with high relative abundances (>1%) across all soil samples, the composition of soil microbial phyla levels revealed different trends following fertilizer management. The abundances of Actinobacteria and Gemmatimonadetes increased, while the abundances of Acidobacteria and Nitrospirae decreased (P < 0.05) following fertilizer management. Among the fungal taxa, the abundances of Ascomycota and Mortierellomycota responded positively to fertilizer. These results were largely influenced by changes in the C:N and N:P ratios in both the soil and microbial biomass. Overall, significantly increased C:N and decreased N:P ratios in the soil reflected the N deficiency that would limit increased microbial biomass and diversity. Together, all of these results indicated that interactions between ecological ratios (C:N:P) and microbial community composition play vital roles in resource imbalance in dynamic environments. Thus, N status should be an important factor for sustainable agricultural management. Moreover, the synergistic effects were better with the combination of C, N, and P or with organic fertilizer than with C, N and P separately.

Fast-growing Larix kaempferi suffers under nutrient imbalance caused by phosphorus fertilization in larch plantation soil

Abstract There are significant differences in the morphological and physiological responses of larch species with contrasting growth rates under fertilization. However, little is known about species-specific differences in responses to nutrient imbalance caused by fertilization. Therefore, in this study, the effects of nitrogen (N) and phosphorus (P) fertilization on the morphological, physiological and chloroplast ultrastructural traits of two contrasting larch species, fast-growing Larix kaempferi and slowly-growing L. olgensis, grown in larch plantation soil, were investigated during two growth seasons. It was shown that N and combined N and P (NP) fertilization increased plant photosynthesis, foliar N contents, chlorophyll contents, and dry mass accumulation and partitioning in aboveground organs in both larch species. Although P fertilization enhanced P accumulation, its presence reduced the N content in soluble proteins in the foliage of both larch species. Yet, P fertilization exhibited some differences in the two species: P fertilization increased photosynthesis, chlorophyll content and biomass accumulation of L. olgensis, while it decreased these parameters dramatically in L. kaempferi. P fertilization increased foliar N content in L. olgensis, while it reduced it in L. kaempferi. P fertilized L. kaempferi had more damaged chloroplast ultrastructure than L. olgensis. In addition, L. kaempferi exhibited lower acid phosphatase activities, and higher photosynthesis and biomass accumulation than L. olgensis, except under P fertilization. L. kaempferi allocated more biomass into needles, except under P fertilization, while L. olgensis allocated more into stems under fertilization. In conclusion, it was shown that nutrient imbalance caused by P fertilization has greater negative effects on a fast-growing species than on a slowly-growing one, and the negative effects are related to differences in acclimation strategies, N partitioning to photosynthetic components, and P transportation and metabolism in the foliage.

Short-Term Response of Switchgrass to Nitrogen, Phosphorus, and Potassium on Semiarid Sandy Wasteland Managed for Biofuel Feedstock

It is important to understand switchgrass (Panicum virgatum L.) productivity with relation to diverse nutrient deficiency conditions in order to optimize continuous biomass production in marginal lands. This study was conducted on a wasteland sandy soil (Aridosol) to assess biomass yield, nutrient uptake and nitrogen (N) recovery of switchgrass, and soil nitrate-N (NO3−-N) accumulation responses to N (120 kg N ha−1), phosphorus (P, 100 kg P2O5 ha−1), and potassium (K, 45 kg K2O ha−1) applications during 2015 and 2016 in Inner Mongolia, China. The experiment layout was a randomized complete block design with fertilizer mixture treatments of N, P, and K (NPK), P and K (PK), N and K (NK), N and P (NP), and a control with no fertilizer input (CK). Plant height and stem diameter remained unaffected by the different fertilizer treatments. Biomass yield with the NPK treatment in 2015 was 8.9 Mg ha−1 and in 2016 it was 7.3 Mg ha−1. In 2015, compared with the NPK treatment, a significant yield reduction of 33.7% was found with PK, 22.5% with NK, 28.1% with NP, and 40.5% with CK; however, in 2016, yield declined significantly only with CK compared to the rest of the fertilizer treatments, for which yields were statistically similar. Plant N content was reduced for the treatment PK (i.e. N omission); conversely, plant P and K content remained unaffected with P and K omission treatments. Plant nutrient uptake, particularly of N and K, was severely decreased by the nutrient omission treatments when averaged across 2 years. Apparent N recovery (ANR; quantity of N uptake per unit of N applied) was reduced for the NP and NK treatments, which led to an increase in soil NO3−-N accumulation in the top 0–20 cm layer, compared with the NPK treatment. However, ANR was the highest (37.2% in 2015) with the NPK treatment, which also reduced soil NO3−-N accumulation. A balanced N, P, and K fertilizer management approach is suggested to sustain switchgrass yield and stand persistence on semiarid, marginal, sandy wasteland.

Changes in soil aggregate‐associated enzyme activities and nutrients under long‐term chemical fertilizer applications in a phosphorus‐limited paddy soil

AbstractPaddy soils in subtropical China are usually deficient in phosphorus (P) and require regular application of chemical fertilizers. This study evaluated the effects of chemical fertilizers on the distribution of soil organic carbon (SOC), total nitrogen (N) and available P, and on the activity of the associated enzymes in bulk soil and aggregates. Surface soils (0–20 cm) were collected from a 24‐yr‐old field experiment with five treatments: unfertilized control (CK), N only (N), N and potassium (NK), N and P (NP), and N, P and K (NPK). Undisturbed bulk soils were separated into &gt;2, 1–2, 0.25–1, 0.053–0.25 and &lt;0.053 mm aggregate classes using wet sieving. Results showed that both NP‐ and NPK‐treated soils significantly increased mean weight diameter of aggregates, SOC, available P in bulk soil and aggregates, as compared to CK. Most SOC and total N adhered to macro‐aggregates (&gt;0.25 mm), which accounted for 64–81% of SOC and 54–82% of total N in bulk soil. The activities of invertase and acid phosphatase in the 1–2 mm fraction were the highest under NPK treatment. The highest activity of urease was observed in the &lt;0.053 mm fraction under NP treatment. Soil organic carbon and available P were major contributors to variation of enzyme activities at the aggregate scale. In conclusion, application of NP or NPK fertilizers promoted the formation of soil aggregates, nutrient contents and activities of associated enzymes in P‐limited paddy soils, and thus enhanced soil quality.

Effects of nitrogen and phosphorus supply on growth and physiological traits of two Larix species

To investigate how nitrogen (N) and phosphorus (P) fertilization affect plant growth, biomass accumulation and allocation, leaf N and P concentration, and also eco-physiological responses of Larix species with contrasting growth characteristics, slow growing (L. olgensis) and fast growing (L. kaempferi) saplings grown in larch plantation soil were exposed to different N and P regimes. The results showed that N and combined N and P (NP) fertilization promoted growth with a higher biomass accumulation, height growth rate (GRH), net photosynthesis rated (Pn), and photosynthetic P-use efficiency (PPUE) in both species, while P fertilization alone had a positive effect on the growth of L. olgensis but a negative effect on that of L. kaempferi. Moreover, N and NP fertilization increased the photosynthetic N-use efficiency (PNUE) of L. olgensis, while all fertilization treatments decreased that of L. kaempferi. Furthermore, P fertilization increased the N concentration of L. olgensis leaves but had no influence on that of L. kaempferi leaves, while it decreased the NSC concentration of L. olgensis leaves but stimulated the accumulation of starch, fructose and NSC in L. kaempferi leaves. In addition, L. kaempferi with higher GRH showed a greater biomass accumulation, growth, Pn, PNUE, and PPUE when compared to L. olgensis, except for biomass and PPUE under P fertilization and PNUE under N fertilization. These results indicated that the N and P balance rather than the absolute amount of them enhances the growth of L. kaempferi effectively, and P fertilization affects the morphological and physiological traits of the two larch species differently. We propose that the distinct effects of P fertilization on the two larch species were related to different regulation effects of P fertilization on the N concentration, and on the accumulation and transportation of photosynthetic products.

Fatty‐Acid Profiles and Enzyme Activities in Soil Particle‐Size Fractions under Long‐Term Fertilization

Core Ideas Organic treatments significantly enhanced soil organic C, total N, and most enzymes activities. The highest soil organic C, total N, and enzyme activities were existed in 200‐ to 63‐μm fraction. Soil organic C, total N, C/N ratio, α‐glucosidase, sulfatase, β‐glucosidase, β‐cellobiohydrolase, and phenol oxidase activities were significantly correlated with phospholipid fatty acids. A long‐term experiment was established in 1981 to examine the influence of mineral and organic fertilizer on soil organic carbon (SOC), total nitrogen (TN), enzyme activities, and microbial community composition. In this study, we considered 33 yr of the following fertilizer treatments: no fertilizer (control, CK), fertilizer N (N), fertilizer N and P (NP), fertilizer N, P and K (NPK), manure plus fertilizer N, P and K (NPKM), and manure (M). We focused on yellow‐brown paddy soil and its particle‐size fractions of &gt;2000 µm (large macroaggregate sized), 2000–200 µm (coarse sand sized), 200–63 µm (fine sand sized), 63–2 µm (silt sized), and 2–0.1 µm (clay sized). Nutrient concentrations and enzymes, affected by fertilizer treatment and particle fraction, were unevenly active throughout the soils which showed significantly highest concentration and activity in the fine sand fraction, except sulfatase (Sul). However, the coarse sand fraction contributed the largest SOC, TN, and enzyme pools to bulk soil, followed by silt‐sized and large macroaggregate‐sized fractions. Compared with NPK, NPKM, and M treatments significantly improved SOC, TN, phosphatase (Pho), β‐glucosidase (βG), β‐cellobiohydrolase (βCB), N‐acetyl‐glucosaminidase (NAG), β‐xylosidase (βX), phenol oxidase (PhOx), peroxidase activities, and the total phospholipid fatty acids (PLFAs) abundance of soil fractions. Manure also accelerated SOC, TN, and most enzymes accumulation in coarse sand fraction at the expense of clay fraction. Principal component analysis (PCA) of microbial community composition showed a smaller variability in particle‐size fractions than treatments which suggested a considerable effect of soil nutrient availability on microbial community composition. Redundancy analysis (RDA) also convinced SOC, TN, C/N ratio, α‐glucosidase (αG), Sul, βG, βCB, and PhOx activities significantly governed microbial community in this study. Our results conveyed long‐term application of organic fertilizers contributed to the increase of SOC, TN, and most enzyme activities in bulk soil and particle fractions, along with abundant and diverse microbial community in fine sand fraction and other organic treated soil fractions.

Distribution of soil nutrients, extracellular enzyme activities and microbial communities across particle-size fractions in a long-term fertilizer experiment

Soils were particle-size fractionated to evaluate changes in carbon and nitrogen contents, enzyme activities and microbial community composition in response to 33 years of fertilization. This study focused on yellow–brown paddy soil and the particle-size fractions of >2000, 2000–200, 200–63, 63–2 and 2–0.1μm. Microplate fluorometric assays and phospholipid fatty acid analysis (PLFA) were used to determine soil biological characteristics under no fertilizer (control, CK), fertilizer N (N), fertilizer N and P (NP), fertilizer N, P and K (NPK), organic manure plus fertilizer N, P and K (NPKM) and organic manure (M) treatments. The results showed that fertilizer and soil fraction individually and interactively (P<0.05) affected soil C, N contents, enzyme activities and microbial communities except for α-glucosidase activity, bacterial relative abundance and the G+:G− ratio. Particularly, organic treatments significantly increased soil organic carbon (SOC) and total nitrogen (N) contents of all five fractions. The highest C and N contents and enzyme activities were observed in the 200–63μm fraction, except for phosphatase and sulfatase, which showed the highest activities in the 2–0.1μm fraction. The highest activities of β-glucosidase, β-cellobiosidase, α-glucosidase, aminopeptidase, phenol oxidase and peroxidase in each fraction were obtained in the organic treatments (NPKM and M). Activities of phosphatase, sulfatase, N-acetyl-glucosaminidase and β-xylosidase in the 2000–200μm fraction were highest under NPK treatment. PLFA analysis showed that the >63μm fraction contained higher abundance of total PLFAs than that in the 63–0.1μm fraction. Organic treatments significantly enhanced total PLFAs abundance in >2000μm fraction, but decreased PLFAs abundance in the 2000–200μm fraction compared with the NPK treatment. Larger fractions (>2000μm and 2000–200μm) held relatively lower G+:G− ratios and higher fungi:bacteria ratios, which indicated better soil conditions in these fractions. Principal component analysis showed a smaller variability of microbial community composition among treatments than particle-size fractions. Most treatments of larger fractions (>2000μm and 2000–2μm) were well separated from the other fractions. Redundancy analysis showed total N, C:N ratio, phosphatase, sulfatase, N-acetyl-glucosaminidase and β-cellobiosidase activities significantly affected the composition of the microbial community. Significant correlations were also obtained between enzyme activities with SOC, total N and C:N ratio. We concluded that the long-term application of organic fertilizers contributed to improvements in the soil organic carbon and total nitrogen and most of the enzyme activities, especially for the 200–63μm fraction, along with abundant and diverse microbial community composition in larger particles.

养分添加对内蒙古贝加尔针茅草原植物多样性与生产力的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 养分添加对内蒙古贝加尔针茅草原植物多样性与生产力的影响 DOI: 10.5846/stxb201407171461 作者: 作者单位: 沈阳农业大学;农业部环境保护科研监测所,农业部环境保护科研监测所,农业部环境保护科研监测所,沈阳农业大学,农业部环境保护科研监测所,农业部环境保护科研监测所 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目(31170435);国家"十二五"科技计划项目(2012BAD13B07);中央级公益性科研院所基本科研业务费专项资金和农业部产地环境质量重点实验室资助项目;天津市农业环境与农产品安全重点实验室开放基金资助项目 Effects of nutrient addition on plant diversity and productivity in a Stipa baicalensis grassland in Inner Mongolia, China Author: Affiliation: Shenyang Agricultural University;Agro-environmental Protection Institute, Ministry of Agriculture,Agro-environmental Protection Institute, Ministry of Agriculture,Agro-environmental Protection Institute, Ministry of Agriculture,Shenyang Agricultural University,Agro-environmental Protection Institute, Ministry of Agriculture,Agro-environmental Protection Institute, Ministry of Agriculture Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:研究养分添加对草地群落植物组分、结构和多样性格局的影响,对退化草地生态系统恢复与重建具有重要的理论和实践意义。以内蒙古贝加尔针茅(Stipa baicalensis)草原为对象,研究了N、P、K养分添加对草地群落植物多样性和生产力的影响。结果表明:1)养分添加显著提升草原初级生产力,其中氮素添加的效果最明显,NPK复合添加,草原初级生产力与对照相比提高了1.31倍。2)养分添加使草地群落结构发生改变,N素添加显著提高了贝加尔针茅和羊草(Leymus chinensis)为主的禾本科植物功能群在草地群落中所占的比重,而豆科植物功能群在草地群落中所占的比重则显著降低。3)养分添加使草原植物多样性不同程度地减少,其中以N素添加的效应较为显著。 4)在养分添加条件下,植物多样性与草原生产力之间呈负线性相关关系,植物多样性、物种丰富度和物种均匀度与初级生产力的相关系数分别为-0.522、-0.391和-0.534。 Abstract:Stipa baicalensis grassland is a type of meadow steppe that plays an important role in livestock husbandry in China. In recent years, unsustainable grazing, mowing, and other overuse patterns have heavily affected China's grassland ecosystems, resulting in decreased productivity and losses in biological diversity and ecosystem stability. The restoration and sustainable use of grassland ecosystems has become a concern in grassland ecology. Low levels of soil nitrogen (N), phosphorus (P), and potassium (K) often become important factors that limit grassland productivity, while arational application of N, P, K and medium trace element fertilizers can obviously promote the productivityand quality of grasslands. Nutrient addition can affect the structure and diversity of grassland plant communities, and studies on the response of grasslands to adding nutrients will have important theoretical and practical significance to the recovery, reconstruction, and scientific management of degraded grassland ecosystems. We studied the effects of added N,P, and K in a S. baicalensis grasslandto provide a basis for the rational use and protection of grassland resources and the restoration and reconstruction of degraded grassland ecosystems, as well as to lay a foundation for a more general analysis of the relationship between biodiversity and productivity.A randomized block design experiment was conducted with six blocks of eight treatments each: C (control, no nutrient addition), K (K addition only, 100 kg/hm2), P (P addition only, 100 kg/hm2), N (N addition only, 100 kg/hm2), PK (mixed P and K addition, 100 kg/hm2of each element), NK (mixed N and K addition, 100 kg/hm2 of each element), NP (mixed N and P addition, 100 kg/hm2 of each element), and NPK (mixed N, P, and K addition, 100 kg/hm2 of each element).Forty-eight (8 m × 8 m)plots were established with 2 m and 5 m isolation belts between the subplots and main treatment areas, respectively. In 2010,nutrients were applied twice a year with 50% of the treatment amount applied on June 15 and 50% again on July 15 during the grass-growing season.Fieldwork was completed in mid-August during the grass-growing season in 2012. To eliminate edge effects,conditions were measured only in the 6 m × 6 m area in the center of each 8 m × 8 m plot.A 1 m2 (1 m × 1 m)quadrat in each 6 m × 6 m plot was used to record various biological and ecological characteristics including plant composition, plant height,percent ground cover, and vegetation density.We evaluated these characteristics to estimate primary productivity and plant diversity. One-way ANOVA was used to calculate the species richness, the Shannon-Wiener and Pielou indices, and to analyze aboveground biomass. The relationships between the diversity indices and aboveground biomass were determined through linear regression. The results showed that all treatments increased primary productivity and reduced plant diversity. N addition, with or without P or K addition,always significantly decreased the Shannon-Wiener and Pielou indices (except for the NP treatment which had no significant effect), but only the NP treatment resulted in a significant decrease in species richness. With the exception of the K treatment,all treatments resulted in significantly increased primary productivity. Among the three nutrients, N was the most effective treatment in increasing plant productivity and diversity; the NPK treatment had the greatest effect, increasing aboveground biomass 1.31 times compared to that of the control. Nutrient addition altered the community structure in that N addition significantly increased the proportion of grasses and reduced that of legumes, but the effects of nutrient addition on the proportion ofcyperaceae and forbs were negligible. With fertilization, plant diversity (correlation coefficient, -0.522), species richness (-0.391), and species evenness (-0.534) were all negatively linearly correlated with primary productivity. In conclusion, the NPK combination treatment resulted in maximum grassland productivity while effectively maintaining plant diversity, resulting in improved environmental conditions and achievingsustainable development. 参考文献 相似文献 引证文献

RELATIVE PRODUCTIVITY, PROFITABILITY AND WATER USE EFFICIENCY OF CROPPING SYSTEMS IN HOT ARID INDIA

SUMMARYThe choice of an appropriate cropping system is critical to maintaining or enhancing agricultural sustainability. Yield, profitability and water use efficiency are important factors for determining suitability of cropping systems in hot arid region. In a two-year field experiment (2009/10–2010/11) on loam sandy soils of Bikaner, India, the production potential, profitability and water use efficiency (WUE) of five cropping systems (groundnut–wheat, groundnut–isabgol, groundnut–chickpea, cluster bean–wheat and mung bean–wheat) each at six nutrient application rate (NAR) i.e. 0, 25, 50, 75, 100% recommended dose of N and P (NP) and 100% NP + S were evaluated. The cropping systems varied significantly in terms of productivity, profitability and WUEs. Averaged across nutrient application regimes, groundnut–wheat rotation gave 300–1620 kg ha−1 and 957–3365 kg ha−1 higher grain and biomass yields, respectively, than other cropping systems. The mean annual net returns were highest for the mung bean–wheat system, which returned 32–57% higher net return than other cropping systems. The mung bean–wheat and cluster bean–wheat systems had higher WUE in terms of yields than other cropping systems. The mung bean–wheat system recorded 35–63% higher WUE in monetary terms compared with other systems. Nutrients application improved yields, profit and WUEs of cropping systems. Averaged across years and cropping systems, the application of 100% NP improved grain yields, returns and WUE by 1.7, 3.9 and 1.6 times than no application of nutrients. The results suggest that the profitability and WUEs of crop production in this hot arid environment can be improved, compared with groundnut–wheat cropping, by substituting groundnut by mung bean and nutrients application.