Chemical Fertilizer Application Rates Research Articles

Effects of farmyard manure and chemical fertilizer application rates on soil biology, cotton and fiber yield

Organic and inorganic fertilizers have significant effect on plant physiology, yield per unit area, available plant nutrient contents and extracellular enzyme activities of soils. This study was carried out in field conditions in arid and semi-arid regions between 2020-2021 years, May 01. The effects of farmyard manure (FM) (20, 40, 60 Mg ha-1) and chemical (CF) (350 kg urea ha-1, 100, 200, 300 kg DAP ha-1) fertilizers applied at different rates on plant nutrient (N, P, K, Ca, Mg, Fe, Cu, Zn and Mn) contents, SPAD value and NDVI of cotton plants, seed cotton yield and soil enzymes (urease, catalase, dehydrogenase, alkaline phosphatase) were investigated. The results showed that FM applications significantly (p<0.01) increased the plant macro and micronutrients compared to CF applications, except for N (200 + 150 kg urea ha-1), Zn and Cu (300 kg DAP + 200 + 150 kg urea ha-1) in the 2021 cotton growing season. Mineralization of FM is slow under natural conditions; therefore, the use of FM alone is not sufficient to meet the nutrient needs of high yielding varieties. Urease and dehydrogenase activities increased significantly in FM treated soils compared to CF, while no significant (p<0.01) increase was recorded in alkaline phosphatase and catalase activities. Farmyard manure is a useful management practice for increasing soil biological activity. Physiological parameters of NDVI, SPAD and seed cotton yield significantly increased in FM treated soils compared to CF applications. The increase in cotton yield was 29.15%, in NDVI value was 22.38% and in SPAD value was 121.7%. The main issues with cotton in the area are the low organic carbon content of the soils, high clay content, arid and semi-arid soils, and their detrimental impact on the uptake of particular nutrients (N, P and B).

Effect of bio enriched FYM on growth, yield and economics of finger millet (Eleusine coracana (L.) Gaertn) under dryland condition

Crop suffers from the slow release of nutrients from organic manures at initial stages, which may cause a significant reduction in crop yield and farm income. This can be overcome by enrichment of organic manures with beneficial microbial culture and a judicious combination of inorganic fertilizers with such enriched organic manures. Finger millet was grown at AICRP for dryland Agriculture field during Kharif -2019 to study the effect of bio-enriched FYM viz., nitrogen fixers, phosphorus solubilizers, potassium solubilizers, PGPR and microbial consortia with 60 and 80 per cent RDF on growth, yield and economics of finger millet. Application of bio enriched FYM with microbial consortia + 80 per cent RDF (T10) recorded significantly higher plant height (86.38, 111.52 and 115.33 cm), number of tillers per plant (4.42, 5.20 and 5.42) and dry weight per plant (5.50, 15.05 and 27.27 g) at 60, 90 DAS and at harvest, respectively. Whereas, higher grain yield (2999 kg ha-1) and straw yield (4274 kg ha-1) were recorded in T10 treatment Which received 80 per cent RDF with microbial consortia and sème trématent recorded additional return of rupees 12683 per hectare over recommended use of fertilizers. The overall result showed that the bio enrichment of FYM with microbial consortia tended to reduce the application rate of chemical fertilizer and thus microbial consortia along with 80 per cent RDF could be recommended for finger millet.

Variation of Soil Bacterial and Fungal Communities from Fluvo-Aquic Soil Under Chemical Fertilizer Reduction Combined with Organic Materials in North China Plain

Since 2015, China has implemented chemical fertilizer reduction, aiming to achieve zero growth in the application rate of chemical fertilizer. Therefore, it is of great significance to explore the effect of chemical fertilizer reduction combined with organic materials in a wheat-maize rotation system from fluvo-aquic soil in North China on soil microbial community. The field experiment included five fertilization treatments, i.e., chemical fertilizer with conventional application rate (F), chemical fertilizer reduction on the basis of conventional fertilization (FR), chemical fertilizer reduction plus straw (FRS), chemical fertilizer reduction combined with organic fertilizer (FRO), and chemical fertilizer reduction combined with organic fertilizer and straw (FROS). The abundance, composition, diversity, and structure of bacterial and fungal communities among treatments were evaluated using qPCR and Illumina high-throughput sequencing technology. The results showed that the concentrations of soil organic matter (SOM) and total nitrogen (TN) in all treatments with addition of organic materials were much higher than those in treatments applied with only chemical fertilizer. The SOM content in the FRS, FRO, and FROS treatments increased by 23.91%, 37.12%, 26.09%, and the TN content increased by 11.96%, 21.08%, 15.22% in comparison with the F treatment, respectively. The lowest contents of available phosphorus (AP) and nitrate nitrogen (NO3−-N) were observed in FR treatment. The AP content in FRO and FROS treatments were 2.44 times and 2.42 times greater than that in FR treatment, respectively. Compared with F treatment, the organic materials input significantly increased bacterial and fungal abundances. More significant effects on the α-diversity with organic fertilizer were observed in the fungal community compared with the bacterial community. The significant increase of Ascomycota and the decline of Mortierellomycota and Glomeromycota were observed in the combined with organic materials treated soils. The nonmetric multidimensional scaling (NMDS) analysis demonstrated that the bacterial community structure in the F treatment was clearly separated from the other treatments, and the other treatments clustered closely, while with respect to fungal community structure, the FRO and FROS treatments grouped together and were separated from the other three treatments. The redundancy analysis (RDA) results showed that the structure of the bacterial community was significantly correlated with SOM and TN, and the fungal community structure was strongly correlated with AP, SOM, and TN. The chemical fertilizer reduction combined with organic fertilizer and straw can effectively improve soil fertility and nutrient availability, altered the community structure of both bacteria and fungi, but only significantly reduced fungal biodiversity. The influence of chemical fertilizer reduction combined with organic materials on fungi was greater than that on bacteria in fluvo-aquic soil of North China.

Identifying the sources of nitrate in a small watershed using δ15N-δ18O isotopes of nitrate in the Kelan Reservoir, Guangxi, China

China has one of the largest areas of agriculture and one of the highest application rates of chemical fertilizer in the world. Agricultural non-point source pollution has became important source of nitrogen (N) pollution of surface water. In this study, the δ15N and δ18O isotopes of nitrate as a tool were used to reveal the sources of nitrate in water bodies in the Nala watershed, at a sugarcane planted area in Guangxi, China. According to the analyses based on a stable isotope analysis in R (SIAR), the mean contributions of different nitrate sources in the Nala watershed could be ranked as follows: manure (39.90 %) > soil N (SN) (34.94 %) > chemical fertilizer (CF) (17.77 %) > rainfall (7.39 %) in July; manure (42.30 %) > SN (33.54 %) > CF (24.16 %) in December. The CF and SN collectively mean contributing > 50 % of nitrate both in July and in December in the watershed, therefore, reducing the use of CF is the key to control nitrate pollution in the Nala watershed. Manure also composed a substantial contribution (mean 39.68 %, in July and December) to nitrate in the small watershed, it is necessary to provide recycle treatment for manure for the purpose of alleviating the pollution. The δ15N and δ18O isotopes of nitrate can accurately identify various sources of nitrate and SIAR offers a useful method to quantify the contribution rates of different N sources to the N pollution of watersheds.

Growth and Yield Response of Sweet Potato to Different Application Rates of Chemical Fertilizer under Polyethylene Mulch

Growth and Yield Response of Sweet Potato to Different Application Rates of Chemical Fertilizer under Polyethylene Mulch

Assessment of the Potential of Indole-3-Acetic Acid Producing Bacteria to manage Chemical Fertilizers Application

Indole-3-acetic acid (IAA) has a vital role in stimulation of root growth and nutrients acquisition from soil. The study was conducted to isolate rhizospheric (R) and endophytic (E) IAA producer bacteria from the rhizosphere soil and surface sterilized root of wheat, and evaluate the effects of isolates to managing of chemical fertilizers application. For this, we examined the influence of different chemical fertilizer application rates (40, 60, 80 and 100%) coupled with R (Bacillus toyonensis) and E (Pseudomonas mosselii) IAA producer bacteria on wheat growth. Results indicated that supplementing 80% of the recommended chemical fertilizers rate with E isolates resulted in increase of wheat growth indices, which were similar to 100%-fertilizer need without bacterial inoculant. It seems that application of reduced chemical fertilizers integrated with IAA producer bacteria can positively affect the plant growth and led to decrease of chemical fertilizers application. Then optimal condition for IAA release was determined by P. mosselii and B. toyonensis. Results revealed that optimal growth medium conditions for isolates defined to be at l-tryptophan concentration of 3.0 mg mL−1 at 96 h of incubation and 32 °C by spectrophotometry. Increase in l-tryptophan concentration (> 3.0 mg m−1) significantly decreased the IAA production. These results could be attributed to a possible inhibition towards the indigenous (and/or exogenous) soil microbial population by the higher concentrations of l-tryptophan. Glucose used as carbon source, gave the most IAA production (22.9 μg mL−1) in E isolate. About R isolate use of sucrose in the medium culture stimulates IAA production.

Application of Biogas Digestate with Rice Straw Mitigates Nitrate Leaching Potential and Suppresses Root-Knot Nematode (Meloidogyne incognita)

This study investigated the effects of biogas digestate application to soil with rice straw on nitrate leaching potential and nematicidal activity toward root-knot nematodes Meloidogyne incognita. The following seven treatments were set up: (i) control (CONT); (ii) chemical fertilizer (CF); (iii) wet biogas digestate derived from pig manure (WBD); (iv) and (v) dry biogas digestate derived from a mixture of pig manure and rice straw at an initial C/N ratio of 20 and 30 (DBD20 and DBD30); (vi) and (vii) DBD20 mixed with rice straw to adjust the C/N ratio to 16 (Mix1) and 30 (Mix2), respectively. The application rate of CF and digestates was adjusted to 200 mg N kg−1 soil based on the inorganic ammonium nitrogen contents. Nitrate contents readily increased in all the treatments with incubation, except for Mix2, and those at day 90 were decreased with increasing initial labile C contents. Garden balsam was grown as a test plant for root-knot nematodes using the soils at day 90 and the results showed that the gall index was significantly lower in Mix2 and Mix1 than in CF. These results suggest that dry digestate mixed with rice straw might have potential for lower nitrate leaching and nematicidal properties.

Technical training and rice farmers’ adoption of low-carbon management practices: The case of soil testing and formulated fertilization technologies in Hubei, China

More than a decade ago, the Chinese government created several agricultural programs with the objective to promote food security and to foster environmental sustainability via the adoption of more eco-conscious practices in agriculture. While the overall application rate of chemical fertilizer has significantly declined, the adoption of low-carbon technologies promoted through these initiatives remains relative low—partly due to the lack of a wide-reaching systems to implement the recommended practices and farmers' lack of awareness and knowledge about the technologies. The purpose of this study is to examine the impact of technical training on low-carbon management practices, specifically on the adoption of soil testing and formulated fertilization technologies. We hypothesize that technical training and education facilitates the adoption of promoted technologies. Data for this research come from a random sample of 1115 rice farmers in Hubei, China. Using a logistic regression, we empirically examine the effect of having received formal technical training within the last 12 months on the likelihood of adopting low-carbon technologies. To account for potential heterogeneity and selection bias, we employ counterfactual framework and propensity score matching and estimate the average treatment effect for those who have received formal technical training. Our results revealed a positive and significant association between formal technical training and rice farmers’ adoption of low-carbon technologies, with an average treatment effect of 0.2078. Males, younger farmers, and members of agricultural cooperatives were more likely to adopt soil testing and formulated fertilization technologies. Further, a gender analysis, conducted only with those who indicated having received technical training on low-carbon technologies, showed that trained females were more prone to adopt these technologies than trained males. Our findings provide and discuss meaningful implications for the development of future efforts to promote the adoption of low-carbon agricultural technologies in China.

Quantification of nitrogen load in a regulated river system in Vietnam by material flow analysis

In this study, nitrogen (N) loads in Day-Nhue River Basin (DNRB) in Vietnam were quantified (at river basin and province scale) via field observation and application of material flow analysis (MFA). By developing L(Q) curves, measured N loads were estimated from water level data and N content of rivers. N loads from DNRB to Tonkin Gulf were quantified by MFA. The gaps between MFA results and measurements were increased from 4.48 to 21.47% corresponding to the accumulative rainfall from year 2008 to 2010. Results illustrate that MFA can estimate potential N load across the river basin to surface water. Observed ranges in upstream and downstream river loads were different at 55–84% and 5–20% respectively, corresponding well with those estimated by MFA. MFA is effective at quantifying N load to surface water the downstream regions, which are mainly used for paddy agriculture. Original N sources were traced via MFA, identifying that decreasing chemical fertilizer application rates and pretreatment of drainage water before discharging to the surface water reduce N load from the DNRB to the surface water. Additionally, MFA identified a hidden flow in the upstream portion of the DNRB, which meant that measurement data were under-estimated.

Restoration of Long-Term Monoculture Degraded Tea Orchard by Green and Goat Manures Applications System

Tea is an economic shrubby plant in tropical and subtropical regions of the world. To obtain high yield in tea cultivation, chemical fertilizer application rates have generally been used. However, a large quantity of chemical fertilizer application in a long-term continuously ratooned and monoculture tea orchard can inevitably lead to soil acidification and a decline in fertility. Therefore, the restoration of soil fertility and the sustainable development of tea planting by organic ways are critical for the tea industry. In this study, field trials were conducted in the tea orchard that was continuously ratooned and mono-cultured for 20 years. Nitrogen fertilizer (NF), Laredo soybeans green manure (LF), and goat manure (GM) treatments were applied to restore optimum acidity, soil fertility, microbial activity, and the community structure of a long-term continuously monoculture tea orchard. This paper investigated that the pH value was increased from 4.23 to 4.32 in GM and LF, respectively. Similarly, the content of exchangeable acidity (EA) was decreased by 1.21 and 1.46 cmol·kg−1 in GM and LF, respectively. Available nutrient results indicated that the content of NH4+-N was increased by 3.96, 4.38, NO3−-N by 1.07, 2.16, AP by 3.46, 6.86, AK by 0.26, 0.3 mg kg−1 in GM and LF treatments, respectively. Enzyme analysis revealed that the activity of urease and sucrase was promoted by 7.98 mg·g−1·24 h−1 and 6.77 mg·g−1·24 h−1, respectively, in LF treatment. Likewise, the activity of acid phosphatase and polyphenol oxidase was sharply increased by 2.3 mg·g−1 h−1 and 63.07 mg·g−1 h−1 in LF treatments. Additionally, the activity of urease, sucrase, acidic phosphatase, polyphenol oxidase, and peroxidase were also significantly increased by applying GM treatments. Meanwhile, LF and GM treatments significantly improved soil microbial biomass as well as low weight organic acid content in degraded tea rhizosphere. Furthermore, high throughput sequence results illustrated that the relative abundance of Rhizobiaceae and Bradyrhizobiaceae families increased in LF and GM treatments, respectively, which are mostly a kind of nitrogen fixer and plant growth promoting bacteria. Taken together, the physiological traits of the new sprouts and the biochemical components of new tea leaves were also significantly improved by GM and LF treatments. From this study, it is concluded that LF and GM are good agriculture management practices, which promote plant growth, yield, and nutrient availability by maintaining and improving pH, enhancing available nutrients status, improving the secretion of low molecular weight organic acids, and balancing the microbial community structure in the long-term mono-cultured tea orchard.

Combined effects of temperature and precipitation on soil organic carbon changes in the uplands of eastern China

Temperature and precipitation simultaneously influence the soil organic carbon (SOC) in agroecosystems. While these parameters' individual impacts have been extensively studied, their combined effects remain poorly understood at a regional scale. Thus we conducted this study to quantify the combined influence of temperature and precipitation on the SOC in upland-crop fields of the northern Jiangsu Province in eastern China. This quantification was achieved by using the DeNitrification-DeComposition (DNDC, version 9.5) model with the most detailed upland soil database in China. The model simulations indicated that under a scenario where the air temperature (T) increased by 2 °C (T2) and the precipitation (Prec) simultaneously decreased by 20%, the upland soils in the study region were estimated to a sequestered 39.10 Tg C from 2010 to 2039. Meanwhile, a scenario with T2 and a simultaneous increase in Prec by 20% led to a lower C sequestration of 37.39 Tg C. We found that the respective C sequestration from the combined effects of T and Prec in the above two scenarios was 1.24 (or 2.12) Tg C less compared to the sum of their individual effects. Moreover, if the increase of T changed from 2 °C to 4 °C, and the Prec continued to decrease (or increase) by 20%, the C sequestration was 34.69 (or 33.64) Tg C, which was 3.60 (or 3.82) Tg C lower than the sum of the individual effects. Our analysis of the combined effects of T and Prec on the SOC changes suggested that future warming and Prec changes in this region may cause a decrease in the SOC sequestration, but the upland agroecosystems will still serve as a long-term sink for atmospheric CO2 due to the high application rates of chemical fertilizer and farmyard manure. Furthermore, the separate and combined effects of temperature and precipitation on the SOC changes in the different upland soil groups varied widely due to the heterogeneity of soil properties, physicochemical conditions and fertilizer practices. This result emphasized the importance of using fine scale soil datasets and the need to understand the intricacies in the soil carbon sequestration potential at a regional scale in a changing climate.

Response of sunflower to organic and chemical fertilizers in different drought stress conditions

The main objectives of this research were to determine the effects of applying organic and chemical fertilizers under different irrigation regimes on sunflower (Helianthus annuus L.) morphological traits, yield components, grain yield and grain quality. The experiment was conducted as spilt plots based on a randomized complete block design with three replicates. Irrigation treatments at three levels (well-irrigated, mild and severe drought stress) were allocated to main plots and eight fertilizer treatments (urea (F1), urea + composted cattle manure (F2), zeocompost (F3), vermicompost (F4), zeolite-amended chicken manure (Z-ACM) (F5), zeocompost + vermicompost (F6), zeocompost + Z-ACM (F7) and vermicompost + Z-ACM (F8)) were randomized in sub-plots. The results showed that irrespective of the drought stress intensity, organic fertilizer treatments produced more dry matter, heavier and greater grain than did chemical treatments. In well-irrigated plots, the highest grain yield was obtained from F6, F7 and F8 treatments. Under drought stress conditions, the highest grain yield was obtained from the high zeolite content organic fertilizers i.e. F3, F5 and F7. We concluded that amending soil with organic fertilizers in combination with zeolite can be a beneficial approach for decreasing chemical fertilizer application rates and improving the sustainability of agricultural systems.

Effects of different irrigation and fertilization practices on nitrogen leaching in facility vegetable production in northeastern China

Excessive nitrogen fertilizer and irrigation in facility vegetable production cause N leaching, which leads to a series of environmental problems. It is urgent to develop practical management strategies to reduce N leaching while maintaining or increasing yield and water use efficiency (WUE). In the present study, a greenhouse experiment was conducted in the mollisols of northeastern China, where eggplant was planted as the main vegetable. We aimed to evaluate the effects of different fertilization and irrigation practices on N leaching, eggplant yield and WUE. Four treatments were set: applying regular amounts of fertilizer and irrigation (WF), reducing chemical fertilizer application rates by 20% (W80%F), reducing irrigation by 20% (80%WF) and adding biochar into the WF treatment (WF + B). The results showed that the WF + B treatment significantly decreased N leaching while increasing eggplant yield and WUE by 5.5% and 11%, respectively, in comparison with the results of the WF treatment. The amount of N leaching, eggplant yield and WUE in the W80%F treatment were quite similar with those in the WF treatment. Compared with the WF treatment, the 80%WF treatment significantly decreased N leaching and increased WUE; however, it casued a sharp decrease in yield. Our results demonstrated that adding biochar may be a good practice for minimizing N leaching and increasing yield and WUE in facility vegetable production systems.

菌渣化肥配施对稻田土壤微生物量碳氮和可溶性碳氮的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 菌渣化肥配施对稻田土壤微生物量碳氮和可溶性碳氮的影响 DOI: 10.5846/stxb201711272117 作者: 作者单位: 浙江农林大学环境与资源学院,浙江农林大学环境与资源学院,浙江农林大学环境与资源学院,浙江农林大学环境与资源学院,浙江农林大学环境与资源学院,浙江农林大学环境与资源学院,浙江农林大学环境与资源学院 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（31601271）；浙江省自然科学基金（LY16D010010） Effects of the combination of fungal residue and chemical fertilizer on soil microbial biomass carbon and nitrogen and dissolved organic carbon and nitrogen in paddy soil Author: Affiliation: School of Environmental and Resource Science，Zhejiang A＆F University,School of Environmental and Resource Science，Zhejiang A＆F University,,,,, 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:菌渣作为一种养分丰富的有机物料还田，可减少化肥施用，同时保持土壤肥力；而土壤微生物量碳、氮和可溶性碳、氮是土壤活性碳氮库的重要组成部分，其含量和比例变化对土壤肥力均具有重要作用。因此，探讨不同比例菌渣化肥配施对土壤微生物量碳、氮及可溶性碳、氮的影响，评价菌渣在优化土壤肥力方面的生态作用具有重要意义。在水稻田间定位试验条件下，设置3个化肥水平（C）0、50%、100%，菌渣相对用量（F）0、50%、100%，共9个处理，分析了各处理土壤微生物量碳（MBC）、氮（MBN）和可溶性碳（DOC）、氮（DON）的变化特征，及其占土壤有机碳（SOC）和全氮（TN）的比例与相关关系。结果表明：菌渣化肥配施后，微生物量碳和可溶性碳、氮均在C100F50最高，微生物量氮在C50F100最高，与不施肥处理相比，分别显著增加了49.40%、43.65%、83.52%、207.19%；MBC/SOC和DOC/SOC均随着菌渣化肥配施量的增加而减少，MBN/TN和DON/TN均在C100F50最高。相关分析表明，MBC、DOC与SOC，MBN与TN均呈极显著正相关，DON和TN呈显著正相关。总体来讲，菌渣化肥配施能够显著提高土壤微生物量碳、氮和可溶性碳、氮含量，但不是随着用量的增加一直呈增加趋势，高量菌渣或者化肥下会有降低趋势；菌渣化肥配施降低了土壤微生物量和可溶性碳氮比，因此适宜的菌渣化肥配施是提高土壤有机碳周转速度、微生物活性及其氮素供应能力和有效性的最佳选择。 Abstract:As an excellent organic material additive to soil, fungal residue can reduce the application of chemical fertilizer and also plays an important role in maintaining soil fertility. As the most active organic components, soil microbial biomass carbon (MBC) and nitrogen (MBN) and dissolved organic carbon (DOC) and nitrogen (DON) are usually regarded as important and sensitive indices for soil fertility change. Therefore, it is vital to evaluate the ecological and soil fertility significance of fungal residue application under different rates return to the paddy soil. In our study, a randomized complete block field experiment with nine treatments(0,50%, and 100% levels of chemical fertilizers (C) and edible fungal residue (F) were considered, C100F50 stands for 100% of chemical fertilizer and 50% of fungal residue application, etc.) was set up. The changes of MBC, MBN, DOC, and DON, and ratios of these parameters to soil organic carbon (SOC) and total nitrogen (TN) were analyzed. Results showed that the highest contents of MBC, DOC and DON were observed under treatment of C100F50, which were 49.40%, 43.65% and 83.52% higher than that under the treatment of control. Meanwhile highest MBN content was found under treatment of C50F100 which was 207.19% higher than that under the treatment of control. Both ratios of MBC and DOC to SOC were decreased with increased application rate of fungal residue and chemical fertilizer; the highest ratios of MBN and DON to TN were observed in C100F50. There were highly significant positive correlations between MBC, DOC and SOC, respectively, and between MBN and TN as well. The correlation between DON and TN was significantly positive too. In conclusion, application of fungal residue with chemical fertilizer in paddy soil could increase the contents of MBC, MBN, DOC, and DON, but over dosage of fungal residue or chemical fertilizer application could lead to a negative effect. Consequently, the appropriate application rate of chemical fertilizer combined with fungal residue was the optimum choice to improve the SOC turnover rate, microbial activity, and nitrogen supply capacity and efficiency in paddy soil. 参考文献 相似文献 引证文献

Uncertainty and Sensitivity Analyses for Modeling Long-Term Soil Organic Carbon Dynamics of Paddy Soils Under Different Climate-Soil-Management Combinations

AbstractReporting modeling results with uncertainty information can benefit decision making by decreasing the extent that variability exerts a disproportionate influence on the options selected. For making decisions with more confidence, the uncertainty interval should be as narrow as possible. Here, the soil organic carbon (SOC) dynamics of the major paddy soil subgroup from 4 different paddy field regions of China (located in 4 counties under different climate-soil-management combinations) were modeled using the DeNitrification-DeComposition (DNDC) model for the period from 1980 to 2008. Uncertainty intervals associated with the SOC dynamics for these 4 subgroups were estimated by a long-term global sensitivity and uncertainty analysis (i.e., the Sobol? method), and their sensitivities to 7 influential factors were quantified using the total effect sensitivity index. The results, modeled with high confidence, indicated that in the past 29 years, the studied paddy soils in Xinxing, Yixing, and Zhongjiang counties were carbon (C) sinks, while the paddy soil in Helong County was a C source. The 3 C sinks sequestered 12.2 (5.4, 19.6), 17.1 (8.9, 25.0), and 16.9 (−1.2, 33.6) t C ha−1 (values in the parentheses are the 5th and 95th percentiles, respectively). Conversely, the C source had a loss of −5.4 (−14.2, 0.06) t C ha−1 in the past 29 years. The 7 factors, which changed with the climate-soil-management context, exhibited variable influences on modeled SOC. Measures with potential to conserve or sequestrate more C into paddy soils, such as incorporating more crop residues into soils and reducing chemical fertilizer application rates, were recommended for specific soils based on the sensitivity analysis results.

Comparison of Livestock Manure Compost and Chemical Fertilizer Application in Distribution of P Fractions at Reclaimed Land Soils

In order to compare phosphorus (P) behavior of livestock manure compost (LMC) and chemical fertilizer (CF) applied to the sea-reclaimed land soils, incubation experiments were conducted for five weeks. Four soils differing textural classes, sandy loam and clay loam, and electric conductivity (EC) value, high and low, were applied with CF and LMC. LMC was applied at the level of 0, 1, 2, and 3% on the soil weight basis and CF was applied at the same levels of P as LMC. The results showed that increase of P application rate of CF and LMC led to linearly increase available P₂O 5 and 0.01M CaCl₂ extractable P contents regardless of soil texture and EC. However, 0.01M CaCl₂ extractable P from soil applied with CF was significantly higher than with LMC. Correlation analysis between 0.01M-CaCl₂ extractable P and fractionated P by different extraction methods showed that 0.01M-CaCl₂ extractable P positively correlated with KCl-P (soluble and exchangeable P) and HCl-P (Ca and Mg bound P). However, NaOH-P (Fe and Al bound P and organic P) and residual P was adverse. The amount of NaOH-P significantly influenced to the amount of 0.01M CaCl₂ extractable P of CF and LMC in the soils. The application of LMC at sandy loam soil could be carried out in the consideration of nutrient leaching and crop uptake.

Profit Analysis by Soil Carbon Sequestration with Different Composts and Cooperated with Biochar during Corn (<i>Zea mays</i>) Cultivation Periods in Sandy Loam Soil

Despite the ability of biochar to enhance soil fertility and to sequester soil carbon, its potential reduction of green house gas emissions and profit analysis with different organic composts and cooperated with biochar for crop cultivation have been a few evaluated. This study was conducted to estimate their greenhouse gas emission reduction and profit analysis by soil carbon sequestration with different organic composts and cooperated with biochar application during corn cultivation periods. For the experiment, the treatments were consisted of aerobic digestate of swine wastes (AD), pig compost as the control (PC), cow compost (CC) and pig compost cooperated with 1% biochar (PC + 1% biochar). The soil texture used in this study was sandy loam, and application rates of chemical fertilizer were 190-39-221 kg·ha-1 (N-P2O5-K2O) as recommended amount after soil test. The soil samples were periodically taken at every 15 day intervals during the experimental periods. It was observed that soil carbon sequestration by AD, CC and PC + 1% biochar application was estimated to be 429 kg·ha-1, 2366 kg·ha-1, and 3978 kg·ha-1, and their CO2-e emission reductions were estimated to be 0.16 tones for AD, 0.87 tones for CC, and 14.58 tones for PC + 1% biochar per hectar for corn cultivation periods. Their profits were estimated at $14.58 for lowest and $451.90 for highest. In Korea Climate Exchange, it was estimated to be $115.20 per hectar of corn cultivation with PC + 1% biochar. So, the price of CO2 per hectar for corn cultivation with PC + 1% biochar was high at 16.8 times relative to cow compost treatment only. For the plant growth response, it was observed that plant height and fresh ear yield were not significantly different among the treatments. Therefore, these experimental results might be fundamental data for assuming a carbon trading mechanism exists for biochar soil application in agricultural practices.

Adsorption Characteristics and Kinetic Models of Ammonium Nitrogen using Biochar from Rice Hull in Sandy Loam Soil

Objective of this study was to investigate adsorption characteristics and kinetic models of NH₄-N to biochar produced from rice hull in respective to mitigation of greenhouse gases. NH₄-N concentration was analyzed by UV Spectrophotometer. For the experiment, the soil texture used in this study was sandy loam soil, and application rates of chemical fertilizer and pig compost were 420-200-370 kg ha -1 (N-P-K) and 5,500 kg ha -1 as recommended amount after soil test for corn cultivation. Biochar treatments were 0.2-5% to soil weight. Its adsorption characteristic was investigated with application of Langmuir isotherm, and pseudo-first order kinetic model and pseudo-second order kinetic model were used as kinetic models. Adsorption amount and removal rates of NH₄-N were 39.3 mg g -1 and 28.0% in 0.2% biochar treatment, respectively. The sorption of NH₄-N to biochar was fitted well by Langmiur model because it was observed that dimensionless constant (RL) was 0.48. The maximum adsorption amount (q m ) and binding strength constant (b) were calculated as 4.1 mg g -1 and 0.01 L mg -1 in Langmuir isotherm, respectively. The pseudo-second order kinetic model was more appropriate than pseudo-first order kinetic model for high correlation coefficient (r 2 ) of pseudo-second order kinetic model. Therefore, biochar produced from rice hull could reduce N₂O by adsorbing NH₄-N to biochar cooperated in sandy loam soil.

Effect of manure application on seasonal carbon fluxes in a temperate managed grassland in Southern Hokkaido, Japan

Manure application in a managed grassland of reed canary grass in Southern Hokkaido, Japan, promotes carbon (C) sequestration. The objective of the present study is to elucidate the effect of manure application on seasonal change in the C balance components in a managed grassland. Net ecosystem production (NEP), ecosystem respiration (RE), and gross primary production (GPP) were measured using the open-path eddy covariance technique, and heterotrophic respiration from soil (RHs) was measured using the closed chamber method over a period of 2years in the fertilizer and manure plots established in the managed grassland. RE is the sum of autotrophic respiration (RA), RHs, and heterotrophic respiration from manure (RHm). RA in the fertilizer plot was estimated by subtracting RHs from RE. For the manure plot, RA was estimated from GPP multiplied by the RA/GPP ratio, which was assumed to be identical to that in the fertilizer plot. The grass was harvested twice per year, and the aboveground net primary production (ANPP) and aboveground nitrogen (N) uptake were measured at every harvest in the growing season (from the beginning of the growing season until the first crop harvest [G1 season], from the first harvest to the second harvest [G2 season], and from the second harvest to the end of the growing season [G3 season]) and non-growing season (NG). In the manure plot, cattle manure was applied at a rate of 43–44Mg fresh matter (5.8–7.7Mg C) ha−1yr−1 in the spring, and mineral N was supplemented by adding chemical fertilizer in the amount that equalizes the N supply rate to that of the fertilizer plots.Period cumulative NEP and GPP were significantly larger in the fertilizer plot than in the manure plot. In contrast, there was no significant difference in the period cumulative RE between the fertilizer and manure plots. The period cumulative RA, RHs, and RHm were significantly positively correlated with the period cumulative RE. The contribution of RA to RE was the largest, and RHm to RE was only 7% in the manure plot. Mineral supply of N through manure mineralization in the G1 and G2 seasons was estimated at 14±3, and 29±22kgNha−1yr−1, respectively. The ANPP and aboveground N uptake were significantly positively correlated with the application rate of chemical fertilizer N. The ANPP and aboveground N uptake were greater in the G1 season than in the G2 season except for the manure plot in 2005, in which mineralized N present in the manure was not sufficient for grass growth due to low air temperatures in the G1 season. These results suggest that the supplemental application of chemical fertilizer N is recommended in all periods of a grass growing season to increase grass production. Annual net biome production (NBP) was estimated as NEP−C export by harvest+C import by manure application, and the annual NBP was −0.45 and 4.33MgCha−1yr−1 for the fertilizer and manure plot, respectively. This result indicates that manure application is necessary to sequester C in the managed grassland.

Carbon Sequestration and Nitrogen Transformation in Soil Cooperated with Organic Composts and Biochar during Corn (<i>Zea mays</i>) Cultivation

Background: Objectives of this study were to investigate changes of soil carbon contents and to evaluate N mineralization and nitrification rates in soils cooperated with organic composts and biochar during the 2nd year corn cultivation. Methods and Results: For the experiment, the soil texture used in this study was clay loam. Application rates of chemical fertilizer were 480-150- 260 kg/ha (N-P2O5-K2O) as recommended amount after soil test. Biochar application was 0.2% to soil weight. The soil samples were periodically taken at every 15-day interval during corn cultivation periods. The treatments were consisted of cow compost (CC), pig compost (PC), swine digestate from aerobic digestion system (AD), and their biochar cooperation. TC contents in treatments cooperated with biochar at harvesting stages were ranged from 0.96% to 1.24%, and its CC applied plot was highest at 1.24%. It was observed that TC contents with biochar treatments were higher than the compost treatment only. Therefore, it was observed to be carbon sequestration into corn field cooperated with biochar. For nitrogen transformation in soil cooperated with organic composts and biochar, net mineralization rates were dramatically decreased at 44 days after sowing, but nitrification rates were abruptly increased at 73 days after sowing. For N mineralization and nitrification rates, it was shown that they were generally low in the soil cooperated with biochar as compared to the only application plots of different organic composts. Also, it was observed to be highest in the application plot of pig compost manure. Conclusion: Overall, application of biochar in the cropland could be an important role for mitigation of greenhouse gas as well as carbon sequestration.