Long-term Application Of Organic Manure Research Articles

Long-term application of organic manures and chemical fertilizers improve the organic carbon and microbiological properties of soil under pearl millet-wheat cropping system in North-Western India

An on-going long term field experiment started in Rabi 1995 at the Research Farm of the Department of Soil Science, Chaudhary Charan Singh Haryana Agricultural University, Hisar, Haryana (India) under the pearl millet-wheat cropping system was selected to study the effect of long-term application of organic manures and fertilizers on soil organic carbon and microbiological properties. Highest soil organic carbon (SOC: 1.18 %), dissolved OC (DOC: 64.74 mg kg−1) content, microbial biomass C (MBC: 618.40 mg kg−1), dehydrogenase (DHA: 72.83 μg TPF g−1 24 hr−1), alkaline phosphatase (APA: 685.44 μg PNP g−1 soil hr−1) and aryl sulfatase (ASA: 12.56 μg PNP g−1 soil hr−1) activities were observed with the application of 15 Mg FYM+150 kg N+30 kg P2O5 ha−1. Integrated application of chemical fertilizers with pressmud showed superiority in the improvement of microbial biomass nitrogen (MBN: 73.73 mg kg−1) and urease activity (69.54 μg NH4+ g−1 hr−1) than FYM or poultry manure plus NP. Beneficial impacts of the sole application of organic manures on SOC, DOC, MBC content, DHA, APA, and ASA were found in order as: FYM > pressmud > poultry manure. Impacts of nutrient management practices on soil carbon fractions decreased with depth. Poultry manure application, either alone or in combination with NP fertilizers was inferior to FYM and pressmud. The SOC had a positive relationship with MBC (R2 = 0.95) and MBN (R2 = 0.75) and, also showed a highly positive and significant correlation with microbiological properties of soil. This dynamic equilibrium among soil properties indicated that the nutrient management practices that improve SOC could lead to improve soil fertility and accrued microbiological properties in these soils. This study revealed that conjuctive use of organic manures and chemical fertilizers have positive impact on soil fertility and microbiological properties as compared to sole application of organic manures or fertilizers; and among organic manures, FYM was superior to pressmud followed by poultry manure.

Impact of Long-Term Organic Manure Application on Yield, Zinc, and Copper Uptake in Maize, Peas, and Mungbean (Vigna radiata L.) Cropping System

To evaluate the impact of the long-term application of organic manures on yield, uptake of zinc and copper in maize, peas and summer mungbean cropping systems, a field study was conducted at the integrated farming system of Punjab Agricultural University, Ludhiana. The treatment combinations were; T1: 50% N through recommended NPK + 50% N was substituted through FYM, T2: 100% N through FYM, T3: T2 + intercropping (marigold in pea, cowpea in maize), T4: T2 + agronomic practices for weed and. pest control, T5: 50% N as FYM + rock phosphate to substitute the P requirement of crops + phosphate solubilizing bacterial. cultures (PSB), T6: T2 + biofertilizer (consortium) containing N and P carriers and T7: 100% Recommended NPK through chemical fertilizers. Significant increases in the yield, micronutrient content and uptake were recorded due to the application of 50% nitrogen through farmyard manure (FYM) and 50% of the recommended dose of fertilizers (T1) followed by 100% N through FYM + biofertilizer containing. N and P, carriers (T6). The highest grain yield of maize (5.72 t ha-1), pea (16.2 t ha-1) and summer mungbean (11.6 t ha-1) were recorded in treatment T1, surpassing the 100% recommended dose of fertilizer (T7) by 13.7%, 20% and 10.4 %, respectively. The concentration of copper (Cu) and zinc (Zn) in the grains of maize, pea and summer mung bean was 38.3%, 14.1%, 29.6% and 53.4%, 22.8 % and 19.8% higher in treatment T1 as compared to treatment T7. Moreover, the concentration of copper and zinc in the grains of maize, pea and summer mung bean was 32.1%, 24.2% and 29.5 % and 21.7%, 17.6% and 11.6% higher in treatment T1, respectively, compared to treatment T7. Similarly, the increase in the uptake of Cu and Zn was observed in both grain and straw of maize, pea and summer mung bean. The study concluded that the integrated nutrient management (INM) treatment is to substitute a portion of chemical fertilizers with a more sustainable and environmentally safe organic compost in order to mitigate soil degradation, improve crop production, and protect the environment.

Differential Responses of Soil Microbial N-Cycling Functional Genes to 35 yr Applications of Chemical Fertilizer and Organic Manure in Wheat Field Soil on Loess Plateau

Fertilization changes nitrogen (N)-cycling processes and associated microbial communities in agricultural ecosystems. However, the long-term responses of N-cycling potential and microbial functional genes to different fertilization sources remain unclear. Soil samples were collected to a depth of 20 cm under winter wheat applied annually with N fertilizer (NF), organic manure (OM), N fertilizer plus organic manure (NM), and a control without fertilization (CK) for 35 yr, and they were analyzed for microbial functional genes involved in soil N cycling using metagenome sequencing in the Loess Plateau of China. Soil N fractions were greater with OM and NM than NF and CK. The total abundances of N-cycling genes were 9.3% (p < 0.05) greater with NM than CK, and 8.2% (p < 0.05) and 12.2% (p < 0.01) higher with OM and NM than NF, respectively. Compared to CK, OM and NM increased the abundance of genes associated with nitrification, denitrification, dissimilatory nitrate reduction, and assimilatory nitrate reduction, but decreased the abundance of genes related to organic N metabolism. However, NF increased the abundance of genes involved in nitrification. Both OM and NM also enhanced the relative abundance of Proteobacteria carrying N-cycling genes but reduced those of Firmicutes and Cyanobacteria. Soil organic carbon, total N, and potential carbon mineralization were the dominant factors affecting the abundances of N-cycling genes. Long-term application of OM and NM can promote N cycling by enhancing gene abundance due to increased soil organic matter and microbial biomass compared to NF and CK.

Impact of Long-Term Application of Organic Manure on Inceptisol Properties, Grain Protein Content and Yield of Wheat

ABSTRACT A field experiment was conducted to investigate the implications of long-term farm yard manure (FYM) use on chemical and microbial properties of Inceptisol in the North-Western Plain Zone of India, and their correlation with yield and protein content of wheat grains. FYM was used at four different doses (0, 10, 20, 30 t ha−1) with recommended dose of nitrogen, phosphorus and potassium (NPK) as standard practice before sowing of both rice and wheat under rice-wheat cropping system. Application of FYM at 30 t ha−1 significantly enhanced the electrical conductivity (36.36%), nitrogen (29.79%), phosphorus (216.75%), potassium (280.15%), zinc (186.90%), copper (24.23%), organic carbon (130.77%), organic matter (132.43%), operational taxonomic units (OTUs) of top 30 bacterial classes (82.27%), genera (73.95%), plant growth promoting bacteria (PGPB, 86.00%) and lignocellulose degrading bacteria (LDB, 109.14%) over recommended NPK at p value of 0.05. Significantly high plant biomass (14.21 t ha−1) and grain yield (5.69 t ha−1) were obtained in recommended NPK treatment, followed by 30 t ha−1 FYM treatment, whereas significantly higher grain protein was obtained in 30 t ha−1 FYM treatment at p value of 0.05. The abundance of top 30 bacterial classes was highest under 30 t ha−1 FYM (100117), while lowest under recommended NPK treatment (54928). This treatment also witnessed highest presence of all beneficial bacterial classes, top 30 bacterial genera, PGPB and LDB. Highest up-regulated bacterial genes in recommended NPK, and superior soil quality parameters (nutrient profile and microbial diversity) in 30 t ha−1 FYM, indicate that sustainable yields and quality are achievable by using a balanced amount of inorganic fertilizers and organic manure.

Effects of long-term application of organic manure and chemical fertilizer on soil properties and microbial communities in the agro-pastoral ecotone of North China

Long-term irrational fertilizer inputs affect soil nutrients conditions in the agro-pastoral ecotone of North China. However, the mechanisms by which biotic and abiotic factors are affected by different fertilizer types remain unclear. A 16-year, long-term fertilization experiment was conducted to explore how soil physicochemical properties and microbial communities respond to different fertilizer types at an experimental site in North China. The key environmental factors that drove changes in soil microbial communities were also determined. In September 2019, soils were collected from plots of four fertilizer treatments: 1) non-fertilization control (CK), 2) chemical fertilization only (CF), 3) organic manure fertilization only (M), and 4) chemical fertilization plus organic manure (CFM). Compared with CK, soil organic matter, total nitrogen, available nitrogen, available phosphorus, and available potassium contents were higher in M and CFM, whereas soil pH was significantly lower in CF. Abundances of dominant soil bacterial phyla Proteobacteria, Bacteroidetes, and Gemmatimonadetes were higher in M and CFM than CK. Abundances of dominant soil fungal phyla Ascomycota was lower in CFM than in other treatments. The pathogenic fungi Fusarium, Paramyrothecium, Cladosporium, and Alternaria had the highest abundances in CK and CF, whereas abundances of the beneficial fungi Mortierella were significantly higher in M and CFM than in CF and CK. According to partial least squares path modeling, differences in fertilizer types had direct positive effects on fungal communities but little effect on bacterial communities. Overall, CFM maintained higher soil fertility and a healthy ecosystem because it increased beneficial microorganisms and inhibited pathogenic microorganisms, whereas CF increased the risk of crop infection with soil-borne diseases. The study provided a better understanding of how long-term fertilization affects microbial community composition and their associated ecosystem functions.

Effects of different long-term fertilization patterns on net carbon sink effect and economic benefits in double cropping rice paddy ecosystem in southern China

There is close relationship between fertilizer managements and net carbon (C) sink effect, economic benefits in rice paddy ecosystem. Based on a long-term (35-year) field experiment, we analyzed the effects of different fertilization patterns on soil C sequestration rate, C density of topsoil, annual C balance, and economic benefits in the double cropping rice paddy in southern China. There were four fertilization treatments, chemical fertilizer alone (MF), rice straw and chemical fertilizer (RF), 30% organic manure and 70% chemical fertilizer (OM), and without any fertilizer input as a control (CK). The results showed that soil C pool in the double cropping rice paddy field under different fertilization treatments changed from 216.02 to 866.74 kg·hm-2·a-1, and soil C pool under OM treatment were significantly higher than that of MF, RF and CK. The soil C sequestration rates in the double cropping rice paddy field under different fertilization treatments ranged from 51.5 to 650.7 kg·hm-2·a-1, and that of C density of topsoil was from 55.64 to 78.42 t·hm-2. The order of soil C sequestration rates and C density of topsoil was OM>RF>MF>CK. The change range of C adsorption in the double cropping rice paddy field ecosystem was from 4.42 to 9.32 t C·hm-2·a-1, with an order of OM>RF>MF>CK. Compared with the MF treatment, soil net C sink under OM and RF treatments increased by 27.6% and 13.6%, respectively. The change range of C cost material input ranged from 1.49 to 2.17 t C·hm-2·a-1, and that of annual economic benefits was from 1.30×103 to 7.83×103 yuan·hm-2·a-1 with an order of RF>OM>MF>CK. The net income of economic benefits of OM, RF and MF treatments were significantly higher than that of CK. Generally, soil C sequestration rate, C sink effect and annual economic benefits were increased by the long-term application of organic manure and rice straw returning together with chemical fertilizer, which could increase soil organic carbon storage in the double cropping rice paddy field of southern China.

Living and Dead Microorganisms in Mediating Soil Carbon Stocks Under Long-Term Fertilization in a Rice-Wheat Rotation.

Although soil microorganism is an active area of research, we are still in the early stages of understanding how living microorganisms influence the accumulations of soil microbial residues under different agricultural practices. Based on a 39-year fertilization experiment, we characterized the soil microbiota and correlated their compositions to soil microbial residues, which are indicated by amino sugars under a rice-wheat rotation. In the present study, fertilization regimes and crop season all exerted significant impacts on the compositions of soil microbial communities and their residues, although no significant difference in the microbial residues was found between soil depth (0–10 cm vs. 10–20 cm). Compared within fertilization regimes, the long-term fertilization, especially the application of organic manure, stimulated the accumulations of carbon (C) and nitrogen in soils and microbial residues. Upland soils in wheat season accumulated more microbial residues, particularly in fungal residues, than paddy soils in rice season. Our results suggested that the long-term application of organic manure favored the growth of soil microbial communities, and then increased the contents of microbial residues, particularly in fungal residues, leading to an enlargement of soil C pools. The keystone taxa Pseudaleuria identified by network analysis showed a significantly positive potential in soil C sequestration by increasing the accumulation of fungal residues. Thus, this study revealed the strong and close connections between microbial communities and their residues, and provided evidence about the critical role of keystone taxa in regulating C sequestration.

Productivity improvement of bread wheat (Triticum aestivum L.) through crop rotation and organic matter application in degraded crop farms of Ethiopian highlands

AbstractBread wheat is one of the most important staple crops in Ethiopia and it is largely produced by smallholder farmers in the highlands of the country. Its productivity is, however, very low below the world average mainly due to the dwindling of soil productivity and depletion of soil fertility as the result of complete removal of crop residues as well as abandoning of crop rotation and organic matter application. Hence, a 3 years experiment was conducted to study the productivity improvement of bread wheat through crop rotation and organic manure application in degraded crop fields of Ethiopian highlands. Both at station and on-farm sites, factorial combinations of five crop rotations (R1+ = bread wheat–clover–potato, R2+ = clover–bread wheat undersowing lupine–potato, R3+ = potato–clover–bread wheat, R4+ = bread wheat undersowing lupine–potato undersowing lupine–bread wheat and R5+ = lupine–potato undersowing lupine–bread wheat) and four manure application rates [M1 = control/without manure, M2 = 2.5 t ha−1 Sesbania green manure (SGM), M3 = 5 t ha−1 fresh cattle manure (FCM) and M4 = 2.5 t ha−1 SGM + 5 t ha−1 FCM] were laid out in a randomized complete block design with four replications. Crop rotation treatments with plus sign (+) indicated that crop residues and/or green manure of preceding crops were incorporated into the soil. Sole bread wheat crop (R1) without manure application (M1) in the first year (2013) was considered as the control and baseline of the study. Results of the study clearly showed that the interaction of R3+ and M4 in 3 years period (2013–2015) enabled to recover the highest grain productivity of bread wheat from 0.95 and 0.69 to 4.83 and 4.14 t ha−1 with the percentile increments of 408.42 and 500.00% at station and on-farm sites, respectively. Thus, long-term application of organic manure with moderate quantity and incorporation of crop residues in pragmatic crop rotation of a vigorous legume before wheat have great potentials for recovering the productivity of bread wheat in degraded crop fields.

Ratio of nitrate to ammonium mainly drives soil bacterial dynamics involved in nitrate reduction processes

Denitrification and dissimilatory nitrate reduction to ammonium (DNRA) influence the nitrate (NO3−) reduction and its final fate in the environment. However, it is unclear how denitrifying and DNRA bacterial communities respond to different environment conditions. Here, we investigated the effects of fertilization and sampling time (April, July and November) on the abundances of nitrogen (N) cycling genes in processes of denitrification and DNRA at different soil depths (0–20, 20–40 and 40–60 cm) based on a long-term fertilization experiment station (initiated in 1987). The abundances of genes involved in NO3− reduction process were determined using quantitative PCR (qPCR) analysis method. Sampling time showed a stronger effect on the abundances of denitrifying and DNRA genes than fertilization. And the effect of fertilization on the abundances of genes involved in NO3− reduction process was decreased with soil depths. Compared with no fertilizer (CK), the application of mineral N fertilizer (N2 and N4) reduced the abundances of denitrification and DNRA genes at 0–20 cm soil depth, regardless of sampling time. However, the application of organic manure combined with mineral N fertilizer (M2N2) clearly increased the abundance of specific denitrifying genes, including napA (NO3− to NO2−) and nosZ (N2O to N2) genes compared with N2 and N4 treatments at 0–20 and 20–40 cm soil depths. Although the abundance of nrfA gene was the highest, the abundance of norB gene was the most sensitive to environmental variation among all the tested N cycling genes. Ratio of NO3− to ammonium (NO3−/NH4+) was significantly correlated with all the denitrifying and DNRA genes. In general, long-term application of organic manure combined with mineral N fertilizer has a potential to mitigate the NO3− leaching and N2O production, and NO3−/NH4+ ratio is an important factor driving the dynamics of bacterial communities involved in the NO3− reduction process.

Effects of Long-Term Application of Chemical Fertilizers and Organic Fertilizers on Heavy Metals and Their Availability in Reddish Paddy Soil

To investigate the effects of long-term fertilization on the accumulation and availability of heavy metals in reddish paddy soil and to analyze the major influencing factors, soil samples were collected after the later rice was harvested in 2018 from a long-term fertilization field experiment that began in 1984. Six treatments were selected, namely CK (control without fertilization), PK (P and K fertilizer), and NPK (N, P, and K fertilizer), and different proportions of organic fertilizer plus chemical fertilizer (M1NPK: 30%M+70%NPK; M2NPK: 50%M+50%NPK; and M3NPK: 70%M+30%NPK), soil chemical properties, total and available heavy metal contents, and the relationships between the available forms of heavy metals and soil chemical parameters and total heavy metals (THM) were analyzed. The results showed that ① long-term fertilization changed the soil chemical properties; compared with those of CK, PK significantly increased the contents of soil available phosphorus (AP) and available potassium (AK), NPK significantly increased the soil organic matter (SOM), cation exchange capacity (CEC), AP, and AK, and the organic fertilizer treatments significantly increased the contents of SOM, CEC, AP, AK, and nitrate (NO3--N). ② There were slight variations in the THM contents under the chemical fertilizer treatments (PK and NPK), whereas the organic fertilizer treatments significantly increased the total contents of Cu, Zn, and Cd. ③ The chemical fertilizer treatments significantly increased the available Cr and As, whereas the organic fertilizer treatments significantly increased the available Cu, Zn, Cr, Cd, As, and Fe. ④ There were significant positive correlations between the available Cu, Zn, Cr, Cd, As, and Fe and the SOM, CEC, AP, and NO3--N. In addition, the available Zn and Cd were significantly positively correlated with the soil pH, whereas the available Pb was significantly negatively correlated with soil pH, SOM, CEC, and NO3--N. ⑤ There were significant positive correlations between the available and total contents of Cu, Zn, and Cd, whereas there were significant negative correlations between the available and total contents of Cr and Fe. ⑥ Redundancy analysis showed that SOM and pH accounted for 80.7% and 5.5% of the variation in THM, whereas the soil CEC, AP, and pH accounted for 81.1%, 4.9%, and 3.3% of the variation in the available heavy metals, respectively. ⑦ The partial least squares path model analysis showed that the path coefficients of the THM, CEC, and AP on the available state of heavy metals were 0.459, 0.417, and 0.293, respectively. Long-term application of organic manure, such as pig manure, significantly improved the soil chemical properties and affected the availability of heavy metals, and soil CEC and AP may play key roles in regulation.

Long-term fertilization alters soil properties and fungal community composition in fluvo-aquic soil of the North China Plain

Different fertilization regimes can substantially influence soil fungal community composition, yet fewer studies try to control for the effects of nitrogen input. Here, we investigated the impact of fertilization with equal nitrogen upon soil properties and soil fungal diversity and community composition in the North China Plain in a long-term field experiment. Long-term (32 years) fertilization regimes were applied with equal amounts of nitrogen: no chemical fertilizer or organic manure; chemical fertilization only; organic manure fertilization only, and; combination of 1/2 chemical fertilizer and 1/2 organic manure. Then we investigated the influence of these four fertilization regimes to soil properties, fungal diversity and community composition. The results showed that applying organic manure significantly influenced soil properties. Illumina MiSeq sequencing and its analysis revealed that organic manure fertilization significantly changed soil fungal alpha diversity, but chemical fertilization did not. Although soil fungal community composition did not differ significantly among all the fertilization regimes at the phylum and class levels, they did show differences in the abundance of dominant fungi. Yet at the genus level, soil fungal community composition, abundance, and beta diversity was affected by all fertilization regimes. Application of organic manure also reduced the abundance of soil-born fungal pathogens such as Fusarium. Our results suggest that long-term application of organic manure could markedly improve soil properties, altering soil fungal community composition and its diversity. Moreover, organic manure fertilization could limit soil-born fungal diseases, to further contribute to soil ecosystem sustainability.

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.

Soil Nematode Abundances were Increased by an Incremental Nutrient Input in a Paddy-upland Rotation System.

SummaryTo study the effect of fertilization on soil nematode communities in a paddy-upland rotation system, an ongoing thirty-three years long-term fertilizer experiment is conducted which includes seven treatments; an unfertilized treatment (control), nitrogen (N), phosphorus (P), potassium (K) fertilizer treatments (N, NP, NPK) and organic manure (M) combined with chemical fertilizer treatments (MN, MNP, and MNPK). The soil nematode community structure and crop yields were determined in 2012 and 2013. Overall total nematode abundance was increased by an incremental nutrient input both in the rice and wheat fields. Total number of nematode was 1.25 – 2.37 times greater in the rice field and was 1.08 – 2.97 times greater in wheat field in the fertilization treatments than in the unfertilized treatment. Soil free-living nematode abundances was significantly (P < 0.001) increased in organic manure combined with chemical fertilizer treatments in rice field. Fungi-feeders and plant-feeding nematodes abundances were not significantly different among treatments in rice and wheat fields. Omnivorous and predatory nematodes were the most dominant groups in the present study. Omnivores, predators and Prodorylaimus abundances were significantly (P < 0.05) higher in organic manure combined with NPK fertilizer treatments than in chemical fertilizer alone and unfertilized treatments both in rice and wheat fields. Stepwise regressions revealed that soil free-living nematodes were significant predictors of rice grain yields (R2 = 0.56, P < 0.001) and omnivorous and predatory nematodes were significant predictors of the wheat grain yield (R2 = 0.89, P < 0.001). Therefore, long-term application of organic manure combined with chemical fertilizer could increase nematode abundances and crop yields. Organic manure combined with chemical fertilizer application was recommended in agricultural ecosystem.

Long-term benefits of combining chemical fertilizer and manure applications on crop yields and soil carbon and nitrogen stocks in North China Plain

Application of manure is reported to effectively improve agricultural soil fertility. However, the potential of annual manure applications to increase stocks of soil organic carbon (SOC) and total nitrogen (TN) needs to be better understood. In this study, we evaluated the long-term (1991–2012) effects of various fertilization regimes on crop yield, and SOC and TN in the topsoil (0–20 cm) of a fluvo-aquic soil in a wheat (Triticum aestivumL.)-maize (Zea mays L.) cropping system in the North China Plain. The treatments included no N fertilizer (PK), chemical N, P, K fertilizers (NPK), NPK plus 22.5 t ha−1 swine manure (NPKM), and NPK plus 33.75 t ha−1 swine manure (NPKM+). Compared with NPK and PK, both NPKM and NPKM+ significantly increased crop yields, with no significant difference between NPKM and NPKM+. NPKM and NPKM+ treatments had a lower N use efficiency (NUE) than NPK through the whole period and the average NUE were 30.1%, 14.8% and 12.3% in NPK, NPKM and NPKM+ treatments, respectively. Compared with the initial value of 17.2–17.4 Mg C ha−1 and 2.01–2.07 Mg N ha−1, SOC and TN stocks in NPKM and NPKM+ increased by 94.7–114.2% and 83.0–98.0% over the 22 experimental years, respectively, without any indication of C or N saturation in the soil. Furthermore, TN stock was positively correlated to SOC stock (P < 0.01) added with manure, indicating the significance of more organic C input from manure to build up TN pool. In conclusion, long-term application of organic manure in combination with conventional chemical fertilization could increase crop yield and soil C and N stocks in the wheat-maize cropping system of the North China Plain, but it should be noted that large amounts of manure N could also lead to elevated risk of environmental N losses.

Long-Term Organic Amendment Application Improves Influence on Soil Aggregation, Aggregate Associated Carbon and Carbon Pools under Scented Rice-Potato-Onion Cropping System after the 9th Crop Cycle

ABSTRACTA field experiment was conducted to investigate the influence of long-term application of organic manures on aggregate stability, associated carbon concentrations and carbon pools as an important soil-quality parameter under a scented rice-potato-onion cropping system in silt-loam textured soil in Eastern Bihar, India (subtropical climatic condition). Five treatments were used: 1) nitrogen, phosphorus and potassium (NPK) – 100% recommended dose of NPK; 2) NPK+FYM (farmyard manure) – 50%NPK+50% N as FYM; 3) FYM+VC (vermicompost)+ NC (neem cake) – different organic sources each equivalent to 1/3 of the recommended N (FYM +VC +NC); 4) FYM+VC+NC+PSB (phosphate-solubilizing bacteria – different organic sources each equivalent to 1/3 of the recommended N (FYM +VC+NC)+biofertilizers containing N and P carriers (PSB) and 5) FYM+BFN+BM+PSB – 50% N as FYM + biofertilizer for N +Bone meal to substitute P requirement of crops + PSB. The aggregate size distribution (>250 μm) at different soil depths is higher in treatment FYM+VC+NC+PSB and is at par with FYM+VC+NC, followed by FYM+BFN+BM+PSB and NPK+FYM, and the lowest in treatment receiving 100% NPK. The mean carbon concentration in each soil fraction was higher in soil depth 0–10 cm, followed by 10–20 cm and 20–30 cm. The trend of mean weight diameter (MWD) in different treatments was FYM+VC+NC+PSB ≥ FYM+VC+NC > NPK+FYM > FYM+BFN+BM+PSB > NPK. The trend of carbon concentrations in different treatments was FYM+VC+NC+PSB ≥ FYM+VC+NC > FYM+BFN+BM+PSB ≥ NPK+FYM > NPK. Non-labile pool of carbon forms the major portion (60.14%) of the total soil organic carbon (SOC) irrespective of all depths. Bulk density (BD) has a significant role in stabilizing soil aggregates as well as increasing the SOC content in soil. SOC was negatively correlated with BD (r = −0.870, p = 0.05), MWD (r = −0.911, p = 0.01) and geometric mean diameter (GMD) (r = −0.958, p = 0.05) irrespective of depth. This study took further steps toward understanding the enhancing of aggregate stability on organic manures addition for soil quality improvement.

Sulphur speciation and availability in long-term fertilized soil: evidence from chemical fractionation and SK -edge XANES spectroscopy

Knowledge of sulphur (S) speciation in soil following applications of chemical and organic fertilizers is important for understanding the availability and fate of S in agricultural ecosystems. Sulphur speciation of the soil in three fields, which are part of the National Long-term Monitoring Network of Soil Fertility and Fertilizer Effects of China, was investigated with a combination of a wet-chemical fractionation scheme and S K-edge X-ray absorption near edge structure (XANES) spectroscopy. Treatments of the soil included no fertilizers (control), regular applications of nitrogen, phosphorus and potassium fertilizers (NPK), or of NPK plus organic manures (MNPK) since 1990. Soil samples were taken from the topsoil (0–20 cm) and subsoil (20–40 cm) horizons in 2011. Chemical fractionation showed that available sulphate was the predominant inorganic S species in the Eutric Cambisol, whereas HCl-extractable sulphate was the main inorganic S species in the Haplic Phaeozem and Calcaric Cambisol. Organic S accounted for up to 77% of total S in all soil samples. Results from the fractionation (inorganic S plus ester-S) and XANES analysis (oxidized S) were correlated (r = 0.585, P < 0.01), which confirmed the presence of HCl-extractable sulphate and the speciation of residual S in soil. Long-term application of organic manures facilitated significantly the accumulation of intermediate and reduced S species and increased total and organic S in the soil (P < 0.01). In contrast, the application of chemical fertilizers (NPK) had little effect on the distribution of organic S species compared with the control. Atmospheric deposition was identified as an important source of S. The combination of chemical fractionation and XANES spectroscopy provided complementary information on the availability and speciation of S in soil. Highlights Availability and species of S are characterized with chemical fractionation and XANES spectroscopy. Insoluble sulphate is identified as an important form of S in the soil regardless of soil pH. Organic manure facilitates the accumulation of organic S in long-term fertilized soil. Atmospheric deposition contributes importantly to the input and cycling of S in soil.

The Influence of Continuous Organic Manure Application on Chemical Properties and Organic Carbon of Cultivated Soils

A study was conducted to determine the effects of short- and long-term application of organic manure on soil chemical properties including soil pH, EC, CaCO3, SOC, and soil available N and P under arid conditions. The solid and liquid organic manure were applied to the soils cropped with the vegetable for either up to 2-years under vegetable plants or 15-years to soils cropped with fruit trees. Soil samples were collected at sampling depths of 0-15, 15-30, 30-45, 45-60 cm. Results showed that the soil organic carbon (SOC) content ranged between 0.6-12 g kg-1 and 1.7-31.5 g kg-1 after organic manure application for one year and 15-years in soil samples cropped with fruit trees, respectively. Moreover, SOC content ranged between 0.6 and 6.4 g kg-1 and 0.9 and 8.6 g kg-1 after organic manure application for the one year and 2-years in soil samples cropped with vegetable, respectively. The highest soil available N (211 mg kg-1) was found after long term application of organic manure (15-years) followed by that (162 mg kg-1) found after the 2-years organic manure application. The higher soil available P (52-60.2 mg kg-1) was also found with 15-years and 2-years application of organic manure. It could be concluded that the addition of organic manure to the soil of arid condition may be suitable for maintaining soil organic carbon and improving soil fertility by increasing N and P availability.

Conventional tillage improves the storage of soil organic carbon in heavy fractions in the Loess Plateau, China

Soil labile organic carbon (C) plays an important role in improving soil quality. The relatively stable fractions of soil organic C (SOC) represent the bulk of SOC, and are also the primary determinant of the long-term C balance of terrestrial ecosystems. Different land use types can influence the distribution patterns of different SOC fractions. However, the underlying mechanisms are not well understood. In the present study, different fractions of SOC were determined in two land use types: a grazed grassland (established on previously cultivated cropland 25 years ago, GG) and a long-term cultivated millet cropland (MC). The results showed that C concentration and C storage of light fractions (LF) and heavy fractions (HF) presented different patterns along the soil profiles in the two sites. More plant residues in GG resulted in 91.9% higher LF storage at the 0–10 cm soil depth, further contributed to 21.9% higher SOC storage at this soil depth; SOC storage at 20–60 cm soil depth in MC was 98.8% higher than that in GG, which could be mainly attributed to the HF storage 104.5% higher than in GG. This might be caused by the long-term application of organic manure, as well as the protection from plough pan and silt- and clay-sized particles. The study indicated that different soil management practices in this region can greatly influence the variations of different SOC fractions, while the conventional tillage can greatly improve the storage of SOC by increasing heavy fractions.

Long-term application of organic manure changes abundance and composition of ammonia-oxidizing archaea in an acidic red soil

Ammonia-oxidizing archaea (AOA) have more importance in ammonia oxidation than ammonia-oxidizing bacteria (AOB) in acidic red soils. The aim of this study was to investigate if the abundance and composition of AOA could be altered by long-term application of organic manure in an acidic red soil. The abundance and composition of AOA were evaluated by polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE) targeting archaeal amoA genes after long-term (24-year) application of mineral fertilizer and/or organic manure. The treatments were: non-fertilized control, mineral nitrogen (N) fertilizer only, mineral N, phosphorus (P) and potassium (K) fertilizer only, organic manure only, and organic manure plus mineral NPK fertilizer. The abundance of archaeal amoA genes was significantly increased after the long-term application of organic manures, either with or without mineral NPK fertilizer. So were the Shannon and Richness diversity indices of AOA deduced from the DGGE patterns. Phylogenetic analyses showed that most of the AOA sequences from various fertilization treatments were affiliated with group 1.1b thaumarchaea and only one with the group 1.1a-associated thaumarchaea. Nitrification potential was significantly increased after the long-term application of organic manures in comparison with the non-fertilized control. Our results strengthened the importance of organic manure in promoting the growth of AOA and thus nitrification potential in the acidic red soils.

EFFECTS OF 30 YEARS REPEATED FERTILIZER APPLICATIONS ON SOIL PROPERTIES, MICROBES AND CROP YIELDS IN RICE–WHEAT CROPPING SYSTEMS

SUMMARYLong-term fertilization experiment has been conducted since 1981 to study the effect of soil management practices on soil fertility, soil carbon and nitrogen sequestration, soil culturable microbe counts and crop yields at the Nanhu Experimental Station in the Hubei Academy of Agricultural Sciences (situated in the middle reach of the Yangtze River and the rice–wheat cropping system). The experiment was designed with the following eight treatments: (1) unfertilized treatment: Control; (2) inorganic nitrogen fertilizer treatment: N; (3) inorganic nitrogen plus inorganic phosphorus fertilizer treatment: NP; (4) inorganic nitrogen, inorganic phosphorus plus inorganic potassium fertilizer treatment: NPK; (5) pig dung compost (manure) treatment: M; (6) inorganic nitrogen fertilizer plus manure: NM; (7) inorganic nitrogen, inorganic phosphorus fertilizer plus manure treatment: NPM and (8) inorganic nitrogen, inorganic phosphorus, inorganic potassium fertilizer plus manure treatment: NPKM. The results showed that long-term application of organic manure in combination with inorganic fertilizer significantly (p&lt; 0.05) increased soil organic C concentrations compared with the corresponding inorganic fertilizers alone. Soil organic C contents were significantly (p&lt; 0.05) increased in balanced application of NPK fertilizers in comparison to unbalanced application of fertilizers. After 30 years of experiment, soil organic C and total N sequestration rate averagely were 0.48 t ha−1year−1and 28.3 kg ha−1year−1in the fertilized treatments respectively; nevertheless, it were 0.27 t ha−1year−1and 9.7 kg ha−1year−1in the unfertilized treatment. Application of organic fertilizer in combination with inorganic fertilizer significantly (p&lt; 0.05) increased culturable microbial counts compared with the corresponding inorganic fertilizers alone. The balanced application of NPK fertilizers significantly (p&lt; 0.05) increased culturable microbial counts compared with unbalanced application of fertilizers. The average grain yield of wheat and rice was significantly (p&lt; 0.05) higher in organic manure combined with inorganic fertilizer treatment than in inorganic fertilizer alone and unfertilized control. Therefore, long-term application of organic manure combined with inorganic fertilizer and balanced application of NPK fertilizers could increase soil organic C and total N sequestration, culturable microbial counts and crop grain yields.