• Authors:
    • Salgado-Garcia, S.
    • Aguirre-Rivera, J. R.
    • Ortiz-Ceballos, A. I.
    • Ortiz-Ceballos, G.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 1
  • Year: 2015
  • Summary: In Central America, the traditional cropping system milpa de ano (summer season) and tornamilpa (winter season) were compared over 3 yr (2007-2009). Our experimental objectives were to measure the performance of a maize ( Zea mays L.)-velvet bean [ Mucuna pruriens (L.) DC. subsp. utilis (Wight) Burck] milpa system throughout the summer and winter cultivation, to detect any problems associated with velvet bean use, and to determine the contribution of this tropical legume to soil fertility and maize productivity. In each crop season (separated in space and time) we used a completely randomized design with a 2*2 factorial arrangement of treatments with five repetitions each: without velvet bean and without fertilizer (-V-F), with velvet bean and without fertilizer (+V-F), without velvet bean and with fertilizer (-V+F), and with velvet bean and with fertilizer (+V+F). Results showed that in the winter milpas the presence of velvet bean significantly increased the soil pH, organic matter content, total N, and decreased soil bulk density. In both cycles (winter and summer), treatment with velvet bean (+V) produced higher grain yield, while the treatment without velvet bean (-V) had a lower production. We concluded that the use of velvet bean in the winter milpa contributed to the restoration of soil fertility and increased yield maize in agricultural systems of the small-holder farmers based on low external input.
  • Authors:
    • Karasawa,Toshihiko
    • Takahashi,Shigeru
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 103
  • Issue: 1
  • Year: 2015
  • Summary: Field experiments were conducted to clarify whether the introduction of several cover crop species increases P uptake of the following wheat and soybean. Four summer cover crops (sorghum, buckwheat, groundnut and crotalaria) and four winter cover crops (oat, rye, vetch and lupin) were tested. Growth and P uptake of succeeding wheat were significantly increased by P fertilizer application and tended to be increased by sorghum, groundnut or crotalaria incorporation, whereas buckwheat did not show positive effects. Growth and P uptake of succeeding soybean were significantly increased by oat or vetch incorporation and tended to be increased by P fertilizer or other cover crop incorporation. These positive effects of cover crops were attributed to the large amount of P incorporation, increase in the P-solubilizing fungal population and/or biomass P in soil. Sorghum, oat, rye and vetch were thought to be suitable cover crops to accelerate P uptake of the following crops since a large amount of P would be incorporated. Sorghum, groundnut and lupin were thought to be suitable cover crops because they increased the indigenous P-solubilizing fungal population in soil. Soil biomass P correlated with P uptake of wheat. Incorporation of suitable cover crops as a P source and activation of indigenous soil microorganisms by the carbon supply were thought to have accelerated P uptake of the following wheat and soybean. It is therefore thought that introduction of suitable cover crops could be an effective means to reduce P fertilizer application for the following crops.
  • Authors:
    • Nishina,Kazuya
    • Sudo,Shigeto
    • Yagi,Kazuyuki
    • Sano,Tomohito
    • Takata,Yusuke
    • Obara,Hiroshi
    • Eguchi,Sadao
    • Oura,Noriko
    • Yano,Shinji
    • Ohkoshi,Satoru
    • Fujita,Yutaka
    • Shiratori,Yutaka
    • Tsuji,Masaki
    • Hasukawa,Hiroyuki
    • Suzue,Yasufumi
    • Yamada,Yasunao
    • Mizukami,Hiroyuki
    • Uezono,Ichiro
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 103
  • Issue: 1
  • Year: 2015
  • Summary: The use of N fertilizers for agricultural production acts as a sources of atmospheric . Fertilizer induced emission considerably varies in accordance with environmental factors. We conducted a flux measurement campaign across 10 different experimental sites with various soil types throughout Japan and investigated the fertilizer induced emission factors (FIEFs) of synthetic fertilizers (mainly urea) in multiple growing periods at each experimental site. FIEFs considerably varied among the 10 sites, and measurement periods ranged from 0.00 to 7.13 % in 40 total observations. Soil profile information divided the experimental sites into two major groups through cluster analysis, which are volcanic or non-volcanic soils. According to this classification, FIEFs were clearly differentiated into high and low FIEF groups (mean values: 2.67 and 0.59 %, respectively). Regression trees selected total soil carbon, the depth to the Fe mottling horizon, and mean air temperature as the key parameters to determine the strength of FIEFs out of 10 explanatory variables (e.g., N fertilizer application rates, fertilizer application times, clay content, total precipitation during measurement periods, pH, total soil carbon, and total soil nitrogen). The existence of shallow Fe mottling layer (up to 42.5 cm) induced high FIEFs in this model, suggesting that upward emissions derived from the intermediate Fe mottling layers presumably contributed high emissions in such soils. Our results suggest that the soil profile information associated with the water regime is an important index for synthetic fertilizer induced emissions.
  • Authors:
    • Nugroho,P. A.
    • Shimizu,M.
    • Nakamato,H.
    • Nagatake,A.
    • Suwardi,S.
    • Sudadi,U.
    • Hatano,R.
  • Source: Plant, Soil and Environment
  • Volume: 61
  • Issue: 9
  • Year: 2015
  • Summary: The effect of mineral fertilizer (F) and mineral combined with organic fertilizer (MF) on N 2O flux in grassland and cornfield was investigated for one year in Southern Hokkaido, Japan. Annual N 2O flux was higher in grassland than in cornfield, and it was higher in MF plot (14.9 kg N/ha/period) than in F plot (11.1 kg N/ha/period) in grassland. However, in cornfield, the annual N 2O flux was equal between both plots (5.6 kg N/ha/period). These results clarified that high nitrogen application was not always responsible for the high soil N 2O flux. N 2O flux was significantly correlated with air, soil temperature and water-filled pore space. More than 80% of the annual N 2O flux occurred before freezing and less than 4% during melting period. Denitrification was the main process of N 2O flux during study, it was evidenced by the distribution of N 2O and NO ratio which is from 1 to 1000. The denitrification activity (DEA) potentially increased in grassland soil in the beginning and the end of winter season when NO 3-N was abundant; on the other hand the abundance of carbon potentially increased DEA in cornfield soil.
  • Authors:
    • Gao,H.
    • Shao,M.
  • Source: Soil and Tillage Research
  • Volume: 153
  • Year: 2015
  • Summary: Accurate simulation of the effects of temperature on soil water movement processes is lacking in the study of hydrothermal interactions in soil systems. Previous research has proposed some likely mechanisms (e.g., surface tension-viscous flow) to explain soil hydraulic properties in relation to temperature, but little research has focused on the temperature dependence of soil particles (e.g., thermal expansion). Using simulation analyses and experimental data, the effect of temperature on soil hydraulic properties was explored focusing on the thermal effect of water surficial properties and soil particle characteristics. Two temperature coefficients, λ, representing the thermal effect of water surficial properties and c, representing the thermal effect of soil particle characteristics are introduced into soil hydraulics formulae to represent temperature dependence. Results show that temperature-dependent changes in water surficial properties including kinematics viscosity, surface tension and water density effects on soil hydraulic properties. Changes in temperature also affect soil particles, soil porosity and the interactive surface between liquid and solid, especially in heavy loam with high clay content. Expected soil hydraulic properties were calculated at three temperatures in two soil types and then compared to corresponding experimental results. Comparison of predicted and experimental soil hydraulic properties revealed overall similarities with a few exceptions. This study represents an initial simulation study of the effects of temperature on soil hydraulic properties. © 2015.
  • Authors:
    • Shimoda, S.
    • Hayashi, K.
    • Koga, N.
  • Source: Journal
  • Volume: 62
  • Issue: 1
  • Year: 2015
  • Summary: In the context of sustainable soil-quality management and mitigating global warming, the impacts of incorporating raw or field-burned adzuki bean (Vigna angularis (Willd.) Ohwi & Ohashi) and wheat (Triticum aestivum L.) straw residues on carbon dioxide (CO2) and nitrous oxide (N2O) emission rates from soil were assessed in an Andosol field in northern Japan. Losses of carbon (C) and nitrogen (N) in residue biomass during field burning were much greater from adzuki bean residue (98.6% of C and 98.1% of N) than from wheat straw (85.3% and 75.3%, respectively). Although we noted considerable inputs of carbon (499 ± 119 kg C ha–1) and nitrogen (5.97 ± 0.76 kg N ha–1) from burned wheat straw into the soil, neither CO2 nor N2O emission rates from soil (over 210 d) increased significantly after the incorporation of field-burned wheat straw. Thus, the field-burned wheat straw contained organic carbon fractions that were more resistant to decomposition in soil in comparison with the unburned wheat straw. Our results and previously reported rates of CO2, methane (CH4) and N2O emission during wheat straw burning showed that CO2-equivalent greenhouse gas emissions under raw residue incorporation were similar to or slightly higher than those under burned residue incorporation when emission rates were assessed during residue burning and after subsequent soil incorporation. © 2015 Japanese Society of Soil Science and Plant Nutrition
  • Authors:
    • Yoshihara, T.
    • Goto, F.
    • Shoji, K.
    • Kitazaki, K.
    • Johkan, M.
    • Hashida, S.
  • Source: Plant and Soil
  • Volume: 374
  • Issue: 1-2
  • Year: 2014
  • Summary: Nitrous oxide (N2O) is a strong greenhouse effective gas (GHG); the primary human source of N2O is agricultural activities. Excessive nitrogen (N) fertilization of agricultural land is now widely recognized as a major contributor. In soil, the microbial processes of nitrification and denitrification are the principal sources of N2O. However, it remains poorly understood how conventional hydroponics influences GHG emission. Here, we compared GHG fluxes from soil and rockwool used for hydroponics under identical nutrient conditions. Tomato plants (Solanum lycopersicum, momotaro) were grown in soil or by hydroponics using rockwool. In situ emissions of CH4, CO2, and N2O, and the abundance of genes involved in nitrification and denitrification were measured during cultivation. Hydroponics with rockwool mitigated CO2 emission by decreasing the microbial quantity in the rhizosphere. Dilution of the nutrient solution significantly decreased N2O emission from rockwool. Although proliferation of nitrifiers or denitrifiers in the rhizosphere did not induce N2O emission, reuse or long-term use of rockwool induced a 3.8-fold increase in N2O emission. Our data suggest that hydroponics has a lower environmental impact and that adequate fertilizer application, rather than bacterial control, governs N2O fluxes in hydroponic cultivation using rockwool.
  • Authors:
    • Makabe, S.
    • Kanazaki, N.
    • Ikeya, K.
    • Watanabe, A.
    • Sugiura, Y.
    • Shibata, A.
  • Source: Journal of Environmental Management
  • Volume: 144
  • Year: 2014
  • Summary: The application of char to agricultural land is recognized as a potential way to sequester atmospheric carbon (C) assimilated by plants in soil, thus decelerating global warming. Such a process would also be expected to improve plant growth and the physical and chemical properties of soil. However, field investigations of the effects of continuous char application have not been reported. In the present study, the effects of repetitive bamboo char application on CO 2, CH 4, and N 2O flux from soil, soil C content, and crop yield were investigated at two upland fields over five crop seasons. Three treatments: chemical fertilizer (CF) applied plots (Control plot); cattle manure (CM) (10 t ha -1) and CF applied plot (CM plot); and bamboo char (20 t ha -1), cattle manure (10 t ha -1), and CF applied plot (Char/CM plot), were arranged in each field. After three crop seasons, the fourth treatment with char was applied without CF (Char plot) was given to one of the fields. CM and/or char were applied every crop season. Gas fluxes were measured using the static chamber method. Seasonal variations in CO 2 flux and total CO 2 emissions were consistently similar between the CM and Char/CM plots and between the Char and Control plots. As such, the decomposition rate of bamboo char was quite small, and the positive or negative effect of char on CM decomposition was not significant in the fields. Soil C analysis provided confirmation of this. CM application enhanced N 2O emission mainly in the summer crop season. The differences in total N 2O emission between the Char/CM and CM plots as well as between the Char and Control plots were insignificant in most cases. Total CH 4 flux was negligibly small in all cases. Although the yield of winter crop (broccoli) in the Char/CM plots was twice observed to be higher than that in the Control and CM plots at one of the fields, in general, the char application had no effect on overall crop yield. Thus, the repeated application of bamboo char had no significant influence on greenhouse gas emissions and crop yields, but a high C accumulating function was found.
  • Authors:
    • Asano,Maki
    • Wagai,Rota
  • Source: Geoferma
  • Volume: 216
  • Year: 2014
  • Summary: Aggregate hierarchy, a fundamental soil feature controlling various physical and biogeochemical processes, is well-studied for soils dominated by crystalline minerals but not for the soils rich in poorly-crystalline or short-range-order (SRO) minerals. We examined the presence and nature of aggregate hierarchy in the surface horizon of an Andisol which is characterized by high concentrations of organic matter and SRO minerals (esp.allophane/imogolite). Several pretreatments were tested to achieve maximum dispersion and the particle-size fractions isolated (53 mu m) were characterized by SEM, XRD, and elemental analyses. Mass distribution as well as physical and chemical characteristics among the isolated size fractions were strongly influenced by the dispersion level, indicating the importance to find optimal dispersion level. Upon minimum dispersion (wet sieving), over 95% of total C was present as >53 mu m aggregates and the C concentration and C:N ratio remained constant across all size fractions. Even after mechanical shaking, >53 mu m and 2-53 mu m fractions accounted for 37% and 41% of total C, respectively. Maximum dispersion was achieved only after sodium saturation pretreatment followed by the sonication at the energy level 5-10 folds higher than normally required for non-volcanic soils (5 kJ While dissolving minor levels of organic matter and metals, the maximum dispersion treatment liberated large amounts of small particles (<2 mu m) that were enriched in N-rich organic matter, SRO mineral, and organo-metallic complex and that accounted for 48% of total mass, 63% of C, N, and 72 to 91% of extractable phases of Al, Si, and Fe by pyrophosphate and acid-oxalate. The step-wise breakdown of macro- and micro-aggregates with concurrent liberation of micron- to submicron-size particles upon the increased levels of dispersion, therefore, represents clear evidence of aggregate hierarchy on this soil type. Due to their abundance and chemistry, the small particles (<02 and 0.2-2.0 mu m fractions) likely acted as strong binding agents to form both micro- and macro-aggregates. Significant positive correlation of organic matter concentration and C:N ratio against the extractable metal concentrations was found when samples of all size fractions and dispersion treatments were combined. We proposed a simple conceptual model for Artdisol aggregate hierarchy to explain the observed variation in the abundance and chemistry of isolated fractions. (C) 2013 Elsevier B.V. All rights reserved.
  • Authors:
    • Shirato, Y.
    • Yonemura, S.
    • Kishimoto-Mo, A. W.
    • Wagai, R.
    • Hiradate, .
    • Yagasaki, Y.
  • Source: Global Change Biology
  • Volume: 19
  • Issue: 4
  • Year: 2013
  • Summary: Temperature sensitivity of soil organic matter (SOM) decomposition may have a significant impact on global warming. Enzyme-kinetic hypothesis suggests that decomposition of low-quality substrate (recalcitrant molecular structure) requires higher activation energy and thus has greater temperature sensitivity than that of high-quality, labile substrate. Supporting evidence, however, relies largely on indirect indices of substrate quality. Furthermore, the enzyme-substrate reactions that drive decomposition may be regulated by microbial physiology and/or constrained by protective effects of soil mineral matrix. We thus tested the kinetic hypothesis by directly assessing the carbon molecular structure of low-density fraction (LF) which represents readily accessible, mineral-free SOM pool. Using five mineral soil samples of contrasting SOM concentrations, we conducted 30-days incubations (15, 25, and 35°C) to measure microbial respiration and quantified easily soluble C as well as microbial biomass C pools before and after the incubations. Carbon structure of LFs (<1.6 and 1.6-1.8 g cm -3) and bulk soil was measured by solid-state 13C-NMR. Decomposition Q10 was significantly correlated with the abundance of aromatic plus alkyl-C relative to O-alkyl-C groups in LFs but not in bulk soil fraction or with the indirect C quality indices based on microbial respiration or biomass. The warming did not significantly change the concentration of biomass C or the three types of soluble C despite two- to three-fold increase in respiration. Thus, enhanced microbial maintenance respiration (reduced C-use efficiency) especially in the soils rich in recalcitrant LF might lead to the apparent equilibrium between SOM solubilization and microbial C uptake. Our results showed physical fractionation coupled with direct assessment of molecular structure as an effective approach and supported the enzyme-kinetic interpretation of widely observed C quality-temperature relationship for short-term decomposition. Factors controlling long-term decomposition Q10 are more complex due to protective effect of mineral matrix and thus remain as a central question.