It is great of importance to better understand the effects of the long-term fertilization on crop yields, soil properties and nitrogen (N) use efficiency in a rotation cropping cultivation system ...under the conditions of frequent soil disturbance. Therefore, a long-term field experiment of 40 years under soybean-maize rotation was performed in a brown soil to investigate the effects of inorganic and organic fertilizers on crop yields, soil properties and nitrogen use efficiency. Equal amounts of
N-labelled urea with 20.8% of atom were used and uniformly applied into the micro-plots of the treatments with N, NPK, M
NPK, M
NPK before soybean sowing, respectively. Analyses showed that a total of 18.3-32.5% of applied N fertilizer was taken up by crops in the first soybean growing season, and that the application of manure combining with chemical fertilizer M
NPK demonstrated the highest rate of
N recovery and increased soil organic matter (SOM) and Olsen phosphorus (Olsen P), thereby sustaining a higher crop yield and alleviating soil acidification. Data also showed that no significant difference was observed in the
N recovery from residue N in the second maize season plant despite of showing a lower
N recovery compared with the first soybean season. The recovery rates of
N in soils were ranged from 38.2 to 49.7% by the end of the second cropping season, and the residuals of
N distribution in soil layers revealed significant differences. The M
NPK treatment demonstrated the highest residual amounts of
N, and a total of 50% residual
N were distributed in a soil layer of 0-20 cm. Our results showed that long-term application of organic fertilizers could effectively promote N use efficiency by increasing SOM and improving soil fertility, and thus leading to an increase in crop yields. This study will provide a scientific reference and guidance for improving soil sustainable productivity by manure application.
Abstract
In view of the problems of low straw decomposition rates and reduced soil fertility in southern Liaoning, China, we investigated the effects of no-tillage mode (NT), deep loosening + deep ...rotary tillage mode (PT), rotary tillage mode (RT) and the addition of decomposing agent (the next is called a decomposer) (NT + S, PT + S, RT + S) on the decomposition proportion of straw, respectively, by using the nylon net bag method in combination with 365-day field plot experiments. The decomposition rules of cellulose, hemicellulose and lignin as well as the dynamics of soil organic carbon (SOC), soil microbial biomass carbon (MBC) and soil dissolved organic carbon (DOC) in straw returned to the field for 15, 35, 55, 75, 95, 145 and 365 days were analyzed. The results showed that in the short term, the decomposition of straw was better in both the rotray tillage and deep loosening + deep rotary modes than in the no-tillage mode, and the addition of decomposer significantly promoted the decomposition of straw and the release of carbon from straw, among them, the RT + S treatment had the highest straw decomposition proportion and carbon release proportion in all sampling periods. After a one year experimental cycle, the RT + S treatment showed the highest proportion of cellulose, hemicellulose and lignin decomposition with 35.49%, 84.23% and 85.50%, respectively, and soil SOC, MBC and DOC contents were also higher than the other treatments with an increase of 2.30 g kg
−1
, 14.22 mg kg
−1
and 25.10 mg kg
−1
, respectively, compared to the pre-experimental soil. Our results show that in the short term, to accelerate the decomposition rate of returned straw and increase the content of various forms of carbon in soil, rotary tillage can be used to return the straw to the field, while also spraying straw decomposer on its surface. This experiment used a new straw decomposer rich in a variety of microorganisms, combined with the comparison of a variety of straw return modes, and in-depth study of straw decomposition effects of cellulose, hemicellulose and lignin. Thus, a scheme that can effectively improve the decomposition rate of straw and the content of various forms of organic carbon in soil within a short period of time was explored to provide theoretical support for the southern Liaoning.
•Increase in biochar dose increased contents of small macroaggregates.•Soil aggregate stability decreased in 47.25 t ha−1 compared to lower doses.•Biochar contents was higher in macroaggregates than ...microaggregate.•Structural equation model showing the potential mechanisms in soil aggregation.
The use of biochar as soil amendment might improve the soil structure and carbon sequestration. However, few studies have focused on the effects of biochar doses on soil aggregates in brown earth. A six-year field experiment was conducted from May 2013 to October 2018. Four biochar doses were tested: 0, 15.75, 31.5, and 47.25 t ha−1 (control, BC1, BC2, and BC3, respectively). The objective of this study was to explore the effects of different biochar doses on soil biological binding agents (soil organic carbon (SOC), glomalin-related soil protein (GRSP), and microbial biomass carbon (MBC)). The ignition method was used to analyze the biochar content within different aggregate fractions. Biochar was applied before sowing in the first year of this experiment, and mineral fertilizer was applied to all treatments every year before sowing. All biochar treatments increased small macroaggregates (0.25–2 mm) and the soil aggregate stability, as reflected by the MWD (mean weight diameter), GMD (geometric mean diameter) and R>0.25mm (proportions of macroaggregates). The aggregate stability increased with increasing biochar dose and then decreased in the BC3 treatment. All biochar treatments increased the SOC content within macroaggregates. Biochar contents increased with the biochar dosage in all soil aggregate fractions except the microaggregate fraction. Biochar increased the amount of biological binding agents and the soil pH; electrical conductivity (EC); cation exchange capacity (CEC); exchangeable K+, Na+ and Mg2+ levels. Structural equation modeling revealed that biochar enhanced SOC first; SOC influenced the small macroaggregate fraction and silt and clay fraction indirectly via MBC, easily extractable glomalin-related soil proteins (GRSPe) and exchangeable Mg2+. However, the reason why the MWD decreased in the BC3 treatment was not clear. Therefore, the use of biochar as a soil amendment might improve the soil structure under a suitable application dose, but the underlying mechanism still requires further research.
•Soil pH determines fertilization strategy and fungal community response.•Long-term inorganic fertilization can achieve high crop yield in alkaline soils.•Acidic soil productivity can be maintained ...by inorganic-organic fertilization.•Mortierella and Pseudaleuria were enriched by inorganic-organic fertilization.
Agricultural fertilization plays a crucial role in crop production, and the fungal communities catalyze transformation of soil nutrients in support of crop production. However, it remains controversial about the optimal strategy for fertilizer inputs and the adaptive mechanisms of fungal communities across China. By using seven long-term field fertilization experiments in China, we analyzed crop yields, soil properties and fungal communities in soils that were treated for > 25 years with no fertilizer (control), inorganic fertilizers (NPK) and organic-inorganic fertilizers (NPKM). Long-term NPK resulted in significant acidification up to a decline by 1.20 pH units, while NPKM prevented acidification and increased pH up to 6.39 in three acidic soils with pH < 5.70. NPKM increased crop yields by 1.19–8.72 folds in acidic soils, being significantly higher than NPK. Specific saprotroph Mortierella and Pseudaleuria in acidic soils were exclusively enriched by NPKM. Soil pH was directly related to the abundance of Mortierella, and the enrichment of Mortierella species further caused a positive direct effect on crop yield. In four alkaline soils with pH > 8.11, both NPK and NPKM led to only marginal decline of soil pH, and NPK and NPKM showed comparable crop yields. Some members of Ascomycota in alkaline soils were both enriched by NPKM and NPK. Soil available P and C:N ratio, rather than pH, directly or indirectly affect crop yield in alkaline soils. High crop yield can be achieved by the sole use of inorganic fertilizers in alkaline soils, but acidic soil productivity should be maintained by organic amendment to counteract acidification by inorganic fertilization. Our study advances a mechanistic understanding for optimizing fertilization strategies towards sustainable agriculture under increasingly intensified fertilizer inputs.
Background
Manures and synthetic fertilisers can affect soil pH and plant-microbe processes and thus influence P forms and composition.
Aims
The objective of this study was to examine the effects of ...the 40-year application of synthetic fertilisers or pig manure combined with synthetic fertilisers on the P forms and composition and the response of corn growth and yield to changes in P availability.
Methods
A long-term field experiment with unfertilised, urea, urea+superphosphate, pig manure+urea and pig manure+urea+superphosphate fertilised soils was studied.
31
P nuclear magnetic resonance spectroscopy was used to quantify P compounds.
Results
The maximum corn yield was found when adding pig manure+urea, despite Olsen-P was lower than on adding manure+superphosphate. Other monoester P compounds, typically related to microbial biomass and processes were highest on adding pig manure+urea. When adding superphosphate+urea+pig manure a reduction of these P compounds was observed as well as the highest accumulation of inositol hexakisphosphate (IHP). Synthetic fertilisers increased Olsen-P, orthophosphate and other monoester and total IHP and largely decreased soil pH. The addition of pig manure greatly increased the stereoisomers of IHP (myo-IHP, scyllo-IHP, neo-IHP, and D-chiro-IHP) and the concentration of orthophosphate diesters. D-chiro-IHP was not found in unfertilised soils while neo-IHP was not detected in synthetically fertilised soils.
Conclusions
P compounds related to microbial processes, such as other monoester, increased when adding pig manure. Additions of superphosphate on top of manures reduced other monoester, while they increased on adding synthetic fertilisers alone. Unfertilised soils were virtually free of P compounds related to microbial processes.
Purpose
Biochar mediation of soil structure and carbon (C) sequestration has been tested, but the underlying mechanisms in this process are poorly understood. We investigated the effects of different ...organic matter applications on soil aggregation and associated C in Northeast China.
Materials and methods
Non-disrupted soil samples (0–20 cm in depth) were collected from the field improvement experiment (established in 2009) with four addition treatments: (1) corn straw (CS), (2) pig manure compost (PMC), (3) biochar from corncob (BIO), and (4) biochar-based compound fertilizer (BF), of which CS, PMC, and BIO were combined with extra mineral fertilizers including nitrogen (N), phosphorus (P), and potassium (K). Soil aggregate distribution and associated C concentrations were estimated using physical fractionation techniques.
Results and discussion
The CS and PMC additions increased mean weight diameter (MWD), large macroaggregate fractions (>2 mm), and small macroaggregate fractions (0.25–2 mm). In contrast, BIO and BF significantly increased silt + clay fractions (< 0.053 mm). Compared with CS and PMC, applying BIO and BF had limited benefits for soil aggregation. Nevertheless, BIO promoted fine and coarse particulate organic matter (POM) accumulation significantly, and BF promoted fine POM accumulation significantly (within small macroaggregates). The concentrations of mMPOM (POM occluded in microaggregates within small macroaggregates) in BF and mPOM (POM within microaggregates) in BIO were the highest (
P
< 0.05).
Conclusions
Biochar addition did not significantly improve soil structure compared to corn straw and pig manure compost treatments, but it was beneficial to SOC accumulation. Furthermore, C sequestration in the organic addition treatments was driven by the POM dynamics, and biochar debris was preferentially incorporated into the < 0.25 mm fractions.
In this study, the effect of mineral fertilizer and organic manure were evaluated on soil microbial biomass, dehydrogenase activity, bacterial and fungal community structure in a long-term (33 years) ...field experiment. Except for the mineral nitrogen fertilizer (N) treatment, long-term fertilization greatly increased soil microbial biomass carbon (SMBC) and dehydrogenase activity. Organic manure had a significantly greater impact on SMBC and dehydrogenase activity, compared with mineral fertilizers. Bacterial and fungal community structure was analyzed by polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE). Long-term fertilization increased bacterial and fungal ribotype diversity. Total soil nitrogen (TN) and phosphorus (TP), soil organic carbon (SOC) and available phosphorus (AP) had a similar level of influence on bacterial ribotypes while TN, SOC and AP had a larger influence than alkali-hydrolyzable nitrogen (AHN) on fungal ribotypes. Our results suggested that long-term P-deficiency fertilization can significantly decrease soil microbial biomass, dehydrogenase activity and bacterial diversity. N-fertilizer and SOC have an important influence on bacterial and fungal communities.
Purpose
Nitrification inhibitor plays an important regulatory role in inhibiting the nitrification of ammonium in soils. However, most of nitrification inhibitors lack the sustainable effects in ...suppressing the nitrification of ammonium. In this study, a novel DMS nitrification inhibitor was prepared and tested to explore its lasting effect of nitrification suppression in black soil.
Materials and methods
Both culture experiments and field trial were performed in black soils. Three kinds of nitrification inhibitors (NIs), dicyandiamide (DCD) with low bioactivity, 3,4-dimethylpyrazole phosphate (DMPP) with high bioactivity, and a novel 3,4-dimethylpyrazole sulfate zinc (DMS) with long half-life, were applied into soils, respectively, and the abundance changes of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) were investigated; then, the accumulation changes of inorganic nitrogen, nitrogen use efficiency, and crop yields were furtherly evaluated.
Results and discussions
A novel DMS nitrification inhibitor with high activity and long half-life maintained a persistent effect of nitrification suppression, and remarkably increased the accumulation of ammonium nitrogen in soil, thus improving nitrogen use efficiency and crop yields. This study implies that lowering the nitrogen loss of nitrification-triggered in soil is of great importance for improving nitrogen use efficiency.
Conclusions
This study provided an insight into the sustainable nitrification suppression of a novel DMS nitrification inhibitor under excessive application of nitrogen fertilizer in black soils. Compared with improving the activity, reasonably prolonging the validity of nitrification inhibitors in soil is a more important strategy increasing the sustainable effects of nitrification inhibition, and the survival period of nitrification inhibitors in soil should be a crucial factor improving nitrogen use efficiency.
Calcium ions (Ca
2+
) regulate plant growth and development during exposure to multiple biotic and abiotic stresses as the second signaling messenger in cells. The extracellular calcium-sensing ...receptor (CAS) is a specific protein spatially located on the thylakoid membrane. It regulates the intracellular Ca
2+
responses by sensing changes in extracellular Ca
2+
concentration, thereby affecting a series of downstream signal transduction processes and making plants more resilient to respond to stresses. Here, we summarized the discovery process, structure, and location of CAS in plants and the effects of Ca
2+
and CAS on stomatal functionality, photosynthesis, and various environmental adaptations. Under changing environmental conditions and global climate, our study enhances the mechanistic understanding of calcium-sensing receptors in sustaining photosynthesis and mediating abiotic stress responses in plants. A better understanding of the fundamental mechanisms of Ca
2+
and CAS in regulating stress responses in plants may provide novel mitigation strategies for improving crop yield in a world facing more extreme climate-changed linked weather events with multiple stresses during cultivation.
Soil microbial diversity is extremely vulnerable to fertilization, which is one of the main anthropogenic activities associated with global changes. Yet we know little about how and why soil ...microbial diversity responds to fertilization across contrasting local ecological contexts. This knowledge is fundamental for predicting changes in soil microbial diversity in response to ongoing global changes. We analyzed soils from ten 20-year field fertilization (organic and/or inorganic) experiments across China and found that the national-scale responses of soil bacterial diversity to fertilization are dependent on ecological context. In acidic soils from regions with high precipitation and soil fertility, inorganic fertilization can result in further acidification, resulting in negative impacts on soil bacterial diversity. In comparison, organic fertilization causes a smaller disturbance to soil bacterial diversity. Despite the overall role of environmental contexts in driving soil microbial diversity, a small group of bacterial taxa were found to respond to fertilization in a consistent way across contrasting regions throughout China. Taxa such as Nitrosospira and Nitrososphaera, which benefit from nitrogen fertilizer addition, as well as Chitinophagaceae, Bacilli, and phototrophic bacteria, which respond positively to organic fertilization, could be used as bioindicators for soil fertility in response to fertilization at the national scale. Overall, our work provides new insights into the importance of local environmental context in determining the responses of soil microbial diversity to fertilization, and identifies regions with acidic soils wherein soil microbial diversity is more vulnerable to fertilization at the national scale.
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