bluuebunny/crossref_metadata_2025 huggingface dataset:
Analytic model of a compound thermal-field emitter and its performance
Authors: Jensen Kevin L. , McDonald Michael , Harris John R. , Shiffler Donald A. , Cahay Marc , Petillo John J.
Published: December 2019

A methodology for implementing the recently developed reformulated general thermal-field equation describing simultaneous thermal and field emission contributions to electron emission is developed, with modifications directed to enhancing speed and accuracy of computation as demanded by emitter characterization and electron beam simulations. An accurate factor to correct both thermal-field (TF) and high field (Fowler-Nordheim or FN) predictions based on a rapid Lorentzian fit model is given. The analytic protrusion model is constructed from modifications to a point dipole model that allow surface elements and field enhancement factors to be rapidly evaluated. The model is applied to an analytical model of a protrusion on a bump in a diode configuration to characterize how current-voltage I(V) relations are affected by TF emission conditions. In addition, it is also shown (i) how aggressively Schottky’s conjecture is undermined as the protrusion dimensions become larger; (ii) how the total current in the TF regime can be substantially larger than predicted by canonical [FN and Richardson-Laue-Dushman (RLD)] formulations; (iii) how an optimal protrusion size may exist; and (iv) how the inference of field enhancement, notional emission area, and work function are poorly predicted using conventional methods relying on the canonical FN and RLD equations even outside the thermal-field regime, even though data can be linear on FN and RLD plots.
Mott insulator to metal transition driven by oxygen incorporation in epitaxial LaTiO3 films
Authors: Zhang T. T. , Gu C. Y. , Mao Z. W. , Chen X. F. , Gu Z. B. , Wang P. , Nie Y. F. , Pan X. Q.
Published: December 2019

Lanthanum titanate, LaTiO3, is an antiferromagnetic Mott insulator with a Ti 3d1 electronic configuration and exhibits an intriguing metallic state in its epitaxial film grown on the SrTiO3 substrate. Here, we explore the driving force of the Mott insulator to metal transition in LaTiO3 epitaxial films by a systematic study of the film growth conditions and biaxial strain using reactive molecular beam epitaxy. Within the achievable range (up to −2.4%) of the biaxial compressive strain in our study, we found that the oxygen incorporation plays a more crucial role than the biaxial epitaxial strain in the Mott insulator to metal transition in LaTiO3 films.
Cortical chimera states predict epileptic seizures
Authors: Lainscsek Claudia , Rungratsameetaweemana Nuttida , Cash Sydney S. , Sejnowski Terrence J.
Published: December 2019

A chimera state is a spatiotemporal pattern of broken symmetry, where synchrony (coherent state) and asynchrony (incoherent state) coexist. Here, we report chimera states in electrocorticography recordings preceding, by several hours, each of seven seizures in one patient with epilepsy. Before the seizures, the onset channels are not synchronized, while the remaining channels are synchronized. During the seizures, this pattern of behavior flips and the nononset channels show a more asynchronous behavior. At a seizure offset, synchrony can be observed that might facilitate termination.
Spectral principal component analysis of the Hβ region of low-redshift SDSS quasars
Authors: Ma Bin , Shang Zhaohui , Brotherton Michael S.
Published: December 2019

Studying the relationships among quasar spectral features is essential to unveil the origins of the emission lines and the quasars’ physical processes. Principal component analysis (PCA) is a powerful tool to investigate correlations between variables. Here, we present the results of PCA on the spectra of low-redshift SDSS quasars. The rest-frame wavelength range studied is 4000 – 5500 Å, involving some typical features of quasar spectra, such as Hβ, [O iii] and Fe ii emission lines. The first principal component is the anti-correlation between [O iii] and Fe ii, the well-known eigenvector one (EV1). The next six principal components also show clear (anti-)correlations between line strengths and/or velocity widths of various features, which agree well with measured spectral properties. By comparing the weights of these principal components with other quasar properties, we can identify their underlying drivers. We find that the second principal component represents spectral slope, and can quantify quasar host fraction, intrinsic slope and reddening well. The third component exhibits the velocity width variation of Hβ, and may be a proxy for orientation. In addition, we calculate the fractional-contribution spectra to investigate which components dominate the variance at individual wavelength ranges. Our results also indicate that the optical Fe ii emission may have distinct origins.
A photometric study of the high-mass-ratio contact binary AV Puppis
Authors: Han Quan-Wang , Li Li-Fang , Jiang Deng-Kai
Published: December 2019

The multi-color photometric light curves for contact binary AV Puppis (AV Pup) in VRcIc
bandpasses are presented and analyzed by using the 2013 version of the Wilson-Devinney (W-D) code. The solutions suggest that AV Pup is a peculiar A-subtype W UMa contact binary with a high mass ratio (q = m
2/m
1 = 0.896) and a low fill-out factor (f = 10%). Combining our newly determined times of minimum with those collected from literatures, the orbital period changes of this system are investigated. The O – C analysis indicates that the orbital period of AV Pup is increasing at a rate of dP/dt = 4.83 × 10−7 days yr−1, which can be explained by mass transfer from the less massive component to the more massive one.
A new strategy for estimating photometric redshifts of quasars
Authors: Zhang Yan-Xia , Zhang Jing-Yi , Jin Xin , Zhao Yong-Heng
Published: December 2019

Based on the SDSS and SDSS-WISE quasar datasets, we put forward two schemes to estimate the photometric redshifts of quasars. Our schemes are based on the idea that the samples are firstly classified into subsamples by a classifier and then a photometric redshift estimation of different subsamples is performed by a regressor. Random Forest is adopted as the core algorithm of the classifiers, while Random Forest and kNN are applied as the key algorithms of regressors. The samples are divided into two subsamples and four subsamples, depending on the redshift distribution. The performances based on different samples, different algorithms and different schemes are compared. The experimental results indicate that the accuracy of photometric redshift estimation for the two schemes generally improves to some extent compared to the original scheme in terms of the percents in

|
Δ
z
|

1
+

z
i

<
0.1

and

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Δ
z
|

1
+

z
i

<
0.2

and mean absolute error. Only given the running speed, kNN shows its superiority to Random Forest. The performance of Random Forest is a little better than or comparable to that of kNN with the two datasets. The accuracy based on the SDSS-WISE sample outperforms that based on the SDSS sample no matter by kNN or by Random Rorest. More information from more bands is considered and helpful to improve the accuracy of photometric redshift estimation. Evidently, it can be found that our strategy to estimate photometric redshift is applicable and may be applied to other datasets or other kinds of objects. Only talking about the percent in

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Δ
z
|

1
+

z
i

<
0.3

, there is still large room for further improvement in the photometric redshift estimation.
A new data structure for accelerating kinetic Monte Carlo method
Authors: Zheng Xu-Li , Quan Dong-Hui , Zhang Hai-Long , Li Xiao-Hu , Chang Qiang , Sipilä Olli
Published: December 2019

The kinetic Monte Carlo simulation is a rigorous numerical approach to study the chemistry on dust grains in cold dense interstellar clouds. By tracking every single reaction in chemical networks step by step, this approach produces more precise results than other approaches but takes too much computing time. Here we present a method of a new data structure, which is applicable to any physical conditions and chemical networks, to save computing time for the Monte Carlo algorithm. Using the improved structure, the calculating time is reduced by 80 percent compared with the linear structure when applied to the osu-2008 chemical network at 10 K. We investigate the effect of the encounter desorption in cold cores using the kinetic Monte Carlo model with an accelerating data structure. We found that the encounter desorption remarkably decreases the abundance of grain-surface H2 but slightly influences the abundances of other species on the grain.
Hydrodynamical simulations of the triggering of nuclear activities by minor mergers of galaxies
Authors: Yang Chao , Ge Jun-Qiang , Lu You-Jun
Published: December 2019

Major mergers of galaxies are considered to be an efficient way to trigger Active Galactic Nuclei and are thought to be responsible for the phenomenon of quasars. This has however recently been challenged by observations of a large number of low luminosity Active Galactic Nuclei at low redshift (z ≲ 1) without obvious major merger signatures. Minor mergers are frequently proposed to explain the existence of these Active Galactic Nuclei. In this paper, we perform nine high resolution hydrodynamical simulations of minor galaxy mergers, and investigate whether nuclear activities can be efficiently triggered by minor mergers, by setting various properties for the progenitor galaxies of those mergers. We find that minor galaxy mergers can activate the massive black hole in the primary galaxy with an Eddington ratio of f
Edd > 0.01 and > 0.05 (or a bolometric luminosity >1043 and >1044 erg s−1) with a duration of 2.71 and 0.49Gyr (or 2.69 and 0.19Gyr), respectively. The nuclear activity of the primary galaxy strongly depends on the nucleus separation, such that the nucleus is more active as the two nuclei approach each other. Dual Active Galactic Nuclei systems can still possibly be formed by minor mergers of galaxies, though the time duration for dual Active Galactic Nuclei is only ∼ 0.011 Gyr and ∼ 0.017 Gyr with Eddington ratio of f
Edd > 0.05 and bolometric luminosity >1044 erg s−1. This time period is typically shorter than that of dual Active Galactic Nuclei induced by major galaxy mergers.
Constraints on individual supermassive binary black holes using observations of PSR J1909–3744
Authors: Feng Yi , Li Di , Li Yan-Rong , Wang Jian-Min
Published: December 2019

We perform a search for gravitational waves (GWs) from several supermassive binary black hole (SMBBH) candidates (NGC 5548, Mrk 231, OJ 287, PG 1302–102, NGC 4151, Ark 120 and 3C 66B) in long-term timing observations of the pulsar PSR J1909–3744 obtained using the Parkes radio telescope. No statistically significant signals were found. We constrain the chirp masses of those SMBBH candidates and find the chirp mass of NGC 5548 and 3C 66B to be less than 2.4 × 109
M
⊙ and 2.5 × 109
M
⊙ (with 95% confidence), respectively. Our upper limits remain a factor of 3 to 370 above the likely chirp masses for these candidates as estimated from other approaches. The observations processed here provide upper limits on the GW strain amplitude that improve upon the results from the first Parkes Pulsar Timing Array data release by a factor of 2 to 7. We investigate how information about the orbital parameters can help to improve the search sensitivity for individual SMBBH systems. Finally, we show that these limits are insensitive to uncertainties in the Solar System ephemeris model.
The jet of FSRQ PKS 1229−02 and its misidentification as a γ-ray AGN
Authors: Zhao Wei , Hong Xiao-Yu , An Tao , Yang Jun
Published: December 2019

Flat-spectrum radio quasar PKS 1229–02 with a knotty and asymmetric radio morphology was identified as the optical and radio counterpart of a γ-ray source. In this paper, we study the properties (e.g. morphology, opacity, polarization and kinematics) of the jet in PKS 1229–02 using radio interferometry. With our results, we find that the knotty and asymmetric morphology of this source may probably shaped by the interaction between its anterograde jet and the nonuniform dense ambient medium. By reproducing a Spectral Energy Distribution of PKS 1229–02 with the obtained kinematic parameters, we find that the relativistic beaming effect in PKS 1229–02 is not strong enough to produce the reported γ-ray emission, i.e. PKS 1229–02 may not be a γ-ray AGN. The misidentification may probably be due to the poor spatial resolution of the γ-ray detector of the previous generation.
Alignment between satellite and central galaxies in the EAGLE simulation: dependence on the large-scale environments
Authors: Zhang Ming-Ge , Wang Yang
Published: December 2019

The alignment between satellite and central galaxies serves as a proxy for addressing the issue of galaxy formation and evolution, and has been investigated abundantly in observations and theoretical works. Most scenarios indicate that the satellites preferentially are located along the major axis of their central galaxy. Recent work shows that the strength of alignment signals depends on the large-scale environment in observations. We use the publicly-released data from EAGLE to figure out whether the same effect can be found in the associated hydrodynamic simulation. We found much stronger environmental dependency of alignment signals in the simulation. We also explore change of alignments to address the formation of this effect.
Early acceleration of electrons and protons at the nonrelativistic quasiparallel shocks with different obliquity angles
Authors: Fang Jun , Lu Chun-Yan , Yan Jing-Wen , Yu Huan
Published: December 2019

The early acceleration of protons and electrons in the nonrelativistic collisionless shocks with three obliquities are investigated through 1D particle-in-cell simulations. In the simulations, the charged particles possessing a velocity of 0.2 c flow towards a reflecting boundary, and the shocks with a sonic Mach number of 13.4 and an Alfven Mach number of 16.5 in the downstream shock frame are generated. In these quasi-parallel shocks with the obliquity angles θ = 15°, 30° and 45°, some of the protons and the electrons can be injected into the acceleration processes, and their downstream spectra in the momentum space show a power law tail at a time of

1.89
×

10

5

ω

pe

−
1

, where ω
pe is the electron plasma frequency. Moreover, the charged particles reflected at the shock excite magnetic waves upstream of the shock. The shock drift acceleration is more prominent with a larger obliquity angle for the shocks, but the accelerated particles diffuse parallel to the shock propagation direction more easily to participate in the diffusive shock acceleration. In the early acceleration stage, more energetic protons and electrons appear in the downstream of the shock for θ = 15° compared with the other two obliquities. Moreover, in the upstream region, the spectrum of the accelerated electrons is the hardest for θ
nB = 45° among the three obliquities, whereas the proton spectra for θ
nB = 15° and 45° are similar as a result of the competition of the effectiveness of the shock drift acceleration and the diffusive shock acceleration.
Forecasts of cosmological constraints from HI intensity mapping with FAST, BINGO and SKA-I
Authors: Yohana Elimboto , Li Yi-Chao , Ma Yin-Zhe
Published: December 2019

We forecast the cosmological constraints of the neutral hydrogen (Hi) intensity mapping (IM) technique with radio telescopes by assuming 1-year of observational time. The current and future radio telescopes that we consider here are Five-hundred-meter Aperture Spherical radio Telescope (FAST), Baryon acoustic oscillations In Neutral Gas Observations (BINGO), and Square Kilometre Array phase I (SKA-I) single-dish experiments. We also forecast the combined constraints of the three radio telescopes with Planck. We find that the 1σ errors of (w
0, wa
) for BINGO, FAST and SKA-I with respect to the fiducial values are respectively, (0.9293, 3.5792), (0.4083, 1.5878) and (0.3158, 0.4622). This is equivalent to (56.04%, 55.64%) and (66.02%, 87.09%) improvements in constraining (w
0, wa
) for FAST and SKA-I respectively relative to BINGO. Simulations further show that SKA-I will put more stringent constraints than both FAST and BINGO when each of the experiments is combined with Planck measurements. The 1σ errors for (w
0, wa
), BINGO + Planck, FAST + Planck and SKA-I + Planck covariance matrices are respectively (0.0832, 0.3520), (0.0791, 0.3313) and (0.0678, 0.2679) implying there is an improvement in (w
0, wa
) constraints of (4.93%, 5.88%) for FAST + Planck relative to BINGO + Planck and an improvement of (18.51%, 23.89%) in constraining (w
0, wa
) for SKA-I + Planck relative to BINGO + Planck. We also compared the performance of Planck data plus each single-dish experiment relative to Planck alone, and find that the reduction in (w
0, wa
) 1σ errors for each experiment plus Planck, respectively, imply the (w
0, wa
) constraints improvement of (22.96%, 8.45%), (26.76%, 13.84%) and (37.22%, 30.33%) for BINGO + Planck, FAST + Planck and SKA-I + Planck relative to Planck alone. For the nine cosmological parameters in consideration, we find that there is a trade-off between SKA-I and FAST in constraining cosmological parameters, with each experiment being more superior in constraining a particular set of parameters.
Effect of plant spacing and type of P fertilizer on soil chemical properties and yield of maize on C type swampland South Kalimantan
Authors: Hadiayompamungkas B , Sulistyaningsih E , Utami S N H , Sosiawan H , Yusuf W A
Published: December 2019

Tidal swampland is one of the suboptimal lands need technology to increasethe yield of maize crops and soil quality. This study aimed to determine the effect of plant spacing and types of P fertilizer on the chemical properties of soil and maize yields, was carried out in type C tidal swampland, and arranged in factorial Randomized Completely Block Design (RCBD). The first factor was the plant spacing, consisting of legowo and zigzag planting system. The second factor was the application of P fertilizer types, namely 1000 kg ha−1 RPR, 250 kg ha−1 SP-36, 1000 kg ha−1 Guano Phosphate, and without P. The results showed that the treatments of P fertilizer type could increase the pH value and available P-nutrient content. Total N content at legowo plant spacing was higher than at zigzag spacing. The highest available K content in all treatments was at 60 days after planting. The zig zag spacing is significant in increasing maize yield by 30% compared to legowo spacing. The provision of RPR fertilizer increased maize yield significantly up to 20%. Therefore, the zigzag spacing and the provision of RPR fertilizer are recommended for maize cultivation in type C tidal swamplands.
Examination of mycorrhizal inoculum for improving maize tolerance to water stress in pot culture using zeolite and Andisol
Authors: Cahyani V R , Suryanti  , Setiawan D F , Suntoro  , Minardi S , Purwanto  , Rahayu
Published: December 2019

Arbuscular mycorrhiza (AM) is known as beneficial microsymbiont that capable to support plant growth by increasing nutrient uptake and improving plant tolerance toward diverse adverse conditions, such as water stress. The present study examined single and mixture mycorrhizal inoculum sources for improving maize tolerance to water stress in pot culture using zeolite and Andisol. Pot culture experiment was conducted using a Factorial Completely Randomized Design with three factors: A: Media type (A0: zeolite, A1: Andisol), B: AM Inoculum sources (B0: No inoculum, B1: Inoculum from Andisol, B2: Inoculum from eight soil types), C: Media moisture level (C1: 50%, C2: 70% of field capacity), with three replications. Each pot contained 300 g of media that sterilized using formaldehyde 2%, Maize were grown until maximal vegetative phase (77 days after planting). The results showed that maize growth on Andisol was higher than on zeolite, inoculum from Andisol were resulted in higher effect than a mixture of inoculum from eight soil types. On zeolite media (A0), inoculum B1 showed to improve plant tolerance to water stress at moisture level of C1 as indicated by plant dry weight (PDW) that 38.6% higher than B2 and 31.9% higher than B0, whereas on Andisol (A1), inoculum B1 resulted PDW 13.4% higher than B2 and 38.4% higher than B0. By AM inoculation in pot culture, maize growth on zeolite media at C1 was lower than at C2, whereas maize growth on Andisol at C1 was higher than at C2 conditions.
The application of various types of organic fertilizer and N, P, K combination on soil fertility, growth and yield of black rice
Authors: Yuniarti A , Machfud Y , Damayani M , Solihin E
Published: December 2019

Black Rice is a source of carbohydrates foodstuff that is a local natural wealth of Indonesia. Black Rice contains a lot of aleurone and endosperm which produce anthocyanin (functions as an antioxidant and antidote to free radicals) so that it has dark purple to black colour. Beside, this black rice also contains fewer sugar levels, more fibre and vitamin E. Other advantages of black rice. It can be used as natural medicine or natural functional food ingredients to treat the body from degenerative diseases such as cancer. Potential yield of black rice is around 4–5 t/ha. Fertilizer is one of the most important factors besides land, labour and capital. Balanced fertilisation has an important role to improve agricultural products. In this study, the extent of the role of various types of organic fertilizers (straw compost, cattle manure, chicken manure and sheep manure) and N, P, K fertilizers on soil quality, the growth and yield of black rice were investigated. The experimental design was carried out using a Randomized Block Design (RBD) consisting of 10 treatments with triplicates. The combination of treatment consisted of straw compost, cattle manure, chicken manure, sheep manure and 0-100% N, P, K. The results showed that the combination of various types of organic fertilizers and N, P, K fertilizers had an effect on plant height, number of tillers and black rice yield (dry grain weight). The application of chicken fertilizers which was added with N, P, K fertilizers for one recommendation gave grain weight of 55.40 g/tiller(7,09 ton/ha).
Understanding nutrient cycles as a key to sustainable forest plantation on tropical peatland in Indonesia
Authors: Sumawinata B , Djajakirana G , Suwardi  , Darmawan
Published: December 2019

Indonesia has around 14 million ha of peatlands which constitutes 7.4% of Indonesia’s land area and very potential to be developed to support national development, especially related to economic strengthening and in enhancing employment opportunities. An expand areas of peatlands in Indonesia are already being utilized for forest plantation of Acacia crassicarpa. To gain clues in understanding how the chemically poor ecosystems can support the plantation, nutrient cycles. The research was carried out in Acacia crassicarpa plantation areas in South Sumatra, Jambi, and Riau, respectively representing shallow, medium, and deep peat. Data collection includes chemical characteristics of the peat, decomposition rate of the litter, fluctuations of the water table, and growth and production of the Acacia crassicarpa. The results show that: a) Acacia crassicarpa growth and production on peatlands much more depend on the nutrient cycles than on the chemical characteristics of the original soil; b) Leaf-fall and the speed of decomposition respectively from the highest to the lowest, are Riau (deep peat), South Sumatra (shallow peat), and Jambi (medium peat); and c) The more leaf-fall produced and the faster the decomposition, the faster is the nutrient cycles and hence the highest is the production of plant biomass.
Relationships between sodium adsorption ratio and water productivity of tomato plants affected by NaCl applications at different growth stages
Authors: Nurlaeny N , Onggo T M , Arifin M , Herdiyantoro D , Setiawan A
Published: December 2019

Under greenhouse condition, tomato plants (Lycopersicon esculentum Mill. cv. Umagna) were planted in the polybags containing a mixture of soil and charcoal husk with a ratio of 2:1 (v:v) and factorial randomized block design was used in this experiment. Four levels of NaCl concentrations (0; 500; 1000 and 2000 mg kg−1, respectively) and three stages of plant growth i.e. vegetative stage (2-4 weeks after transplanting, WAT); generative stage (5-12 WAT) and vegetative until generative stages (2-12 WAT) with three replications. Seedlings of grafted beef tomato cv. Umagna with rootstock of Rampart cultivar at the age of 40 days after transplanting (DAT) were planted in the polybags. Plants were initially watered until the field capacity, then each NaCl concentrations of 200 mL polybag−1 were given at weekly intervals of 2-4 WAT, 300 mL polybag−1 at 5-8 WAT, and 400 mL polybag−1 at 9-12 WAT in combination with freshwater. Application of 2000 mg kg−1 NaCl significantly affected electrical conductivity (EC), water content and organic C, exchangeable Na+, Cl−, Ca2+, Mg2+ and sodium adsorption ratio (SAR) of soil mixed media. The negative correlations between SAR and water productivity (WP) of tomato (r = 0.37-0.89) are caused by NaCl applications at different growth stages
Application of fishpond sediment and water to increase the efficiency of phosphorus fertilization in land integrating agriculture and fishery
Authors: Hartono A , Anwar S , Hazra F , Prasetyo Y S , Putril S M L
Published: December 2019

The utilization of water from Mount Salak by farmers in addition to agriculture activities is also for fishponds that are widely spread among agricultural lands. The phosphate from fishpond sediment and water flowing to the river was supposed contributing to the enriched phosphate in the Jakarta Bay. The use of fishpond sediment and water in agricultural land was expected to decrease the load of phosphate to the river and increase the efficiency of phosphorus (P) fertilization by decreasing P sorption and increasing the release of P. The fishpond sediment with the rates of 0, 2.5%, 5.0%, 7.5% and 10% were combined with fishpond water or distilled water for watering. They were incubated for one month. The experiment was set up in Completely Randomized Design with three replicates. The results showed that fishpond sediment treatments decreased P bonding energies of P sorption and after P desorption and also the rate constant of P sorption. The best treatment in this experiment was the application of 10% of fishpond sediment watered by fishpond water for those determined parameters. The results suggested that application of fishpond sediment and water increased the efficiency of P fertilization in land integrating agriculture and fishery.
The exploration and utilization of functional microorganisms isolated from the tropical peatlands
Authors: Razie F , Saidy A R , Aidawati N
Published: December 2019

The utilization of peatlands may decline the ecological functions of peatlands as carbon sink, water storage and biodiversity source. Therefore, different scientific approaches are required to increase peat productivity and inhibit decline in the ecological functions of peatlands. This article is aimed to provide information on researches that have been carried out in tropical peats in the South Kalimantan Province. The exploration and the potential utilization of microbes was reviewed from several studies conducted in the Desa Landasan Ulin Utara (LaURa), Kota Banjarbaru, South Kalimantan Province. Peat research carried out in the Desa LaURa during the dry season after peat fires in 2015 showed that microbial SRBM (mixture of N fixing, solubilizing P and cellulolytic microorganisms) from the modified recharge bio-pore system was able to improve the growth of roots, stems, and leaves, nutrient uptake, and increase production and biomass of soybean. In another research in 2018, the use of commercial biofertilizers containing Azotobacter sp and Lactobacillus sp applied to the LaURa peats significantly increased the total N and pH of peats but did not accelerate the decomposition of peat materials. In subsequent study on the exploration of nitrogen fixing microorganisms from the LaURa peats (sapric peats) which amounted to 10375-10500 cells g−1, the total N-fixing microbial population was correlated positively to the pH and EC of peats, and correlated negatively to the contents of peat organic C. Combining the results, the total N2 fixing microbial (NFM) population was significantly affected by organic C and peat EC (total NFM population = -154.052 + 33.126 pH + 607.117 EC, R2 = 51.63%). Results obtained from these studies demonstrated that the functional microbes of peatlands are able to maintain ecological functions of the peats.
The opportunity of direct seeding to mitigate greenhouse gas emission from paddy rice field
Authors: Susilawati H L , Setyanto P , Kartikawati R , Sutriadi M T
Published: December 2019

Direct seeded rice (DSR) is one of the options to reduce CH4 emission because it uses less water during initial cropping but it sometimes has side effects such as increasing N2O emissions. The trade-off N2O and CH4 production in rice soils makes a real challenge to reduce the gas production. Nonetheless, few studies have observed the effect of DSR to GHG emission. This study aims to investigate the option of agriculture strategy used to reduce GHG emission without any yield loss through DSR. The study was conducted during rainy season at experimental field of Indonesian Agricultural Environment Research Institute (IAERI), Central Java, Indonesia. We compared the emission of CH4 and N2O, yield and yield components that affected by DSR and TPR practices. Total CH4 emission in TPR was from 352 kg ha−1 season−1 and, it ranged from 187 kg ha−1 season−1 in the DSR. The CH4 emissions were 47% lower for DSR than for TPR during a rice growing season. No significant differences were observed among crop establishments on N2O emissions. GWP were reduced by 46.4% under DSR compare to TPR. Crop-establishment did not influence grain yield, indicating the potential of DSR as alternative methods of establishing lowland rice with low GHG emissions.
Amelioration of Ultisols in West Java Indonesia with microparticle of steel slag
Authors: Devnita R , Hudaya R , Rosana M F , Sandrawati A , Hazarika H
Published: December 2019

Researchs used steel slag as ameliorant had proven that it can improve some soil chemical characteristics. The objective of this reasearch was to investigate the influence of microparticle of steel slag in improving some soil chemical characteristics of Ultisols. The treatments were arrange in Completely Randomized Designed (CRD) with ten treatments: control (without steel slag), steel slag in coarse particle (mesh), and 1-9% (in weight percentage) of microparticle of steel slag. The soil and the treatments were repeated three times and incubated for four months and then be analyzed the change of soil characteristics due to the amelioration after 1, 2, 3 and 4 months of incubation period. The result showed that amelioration of Ultisols with microparticle of steel slag improved several soil characteristics like increased pH, CEC, available P, and exchangeable basic cations like Ca, Mg, K and Na. The treatments did not decrease the P-fixation, however they increased available P.
Soil properties, growth and spears yield quality of five asparagus cultivars grown in tropical soil affected by NaCl applications
Authors: Nurlaeny N , Onggo T M , Arifin M , Setiawan A , Herdiyantoro D , Putra R M
Published: December 2019

To cultivate asparagus (Asparagus officinalis L.) in the tropics is constrained by high temperature and humidity that are potentially stimulating the development of soil-borne diseases. The research was aimed to observe the NaCl applications effects on properties of soil physicochemical, growth and spears yield quality of asparagus in the tropical medium elevation (730 meters above sea levels). The experiment used Split-Plot Design with three levels of NaCl concentrations (1, 2 and 3 g L−1, respectively) as the main plot and five asparagus cultivars (Atlas F1, de Paoli F1, Jing Green F1, San Knight F1 and Jaleo) as the subplot with three repetitions. No interaction was found between NaCl applications and asparagus cultivars at 12 weeks after planting. NaCl concentrations significantly increased soil electrical conductivity (2.14 -2.68dS m−1); levels of soil Na+ (1.77-2.34 cmol kg−1) and Cl- (25.02 -27.79 mg kg−1), but decreased the levels of Ca2+ and Mg2+, respectively by 1.23 and 1.44 cmol kg−1. Higher spears number and weight of asparagus were produced by cultivars of Jaleo (54.3% and 66.4%, respectively) and Atlas F1 (50.9% and 62.6%, respectively). The conclusion shows that Jaleo and Atlas F1 can adapt to the tropical medium environment due to their genetic traits.
Effect of arbuscular mycorrhizal fungi and different composition of growing medium on growth and production of potato seed cultivars Medians in Inceptisols Jatinangor
Authors: Nurbaity A , Hamdani J S , Rahayu R P
Published: December 2019

Arbuscular mycorrhiza fungi (AMF) has been known can increase the productivity of many crops including potatoes. Growing medium is also vital for the growth of potatoes, especially in medium-high land. Good combination of AMF and growing medium is expected to improve the physical and biological soil properties and increase growth and seed production. An experiment aimed to evaluate the effect of AMF and different media composition on growth and yield of potato seeds G2 cultivars Medians in medium land has carried out at Jatinangor, Indonesia. The experiment used randomized block design with treatments: growing medium (soil + compost (2: 1), soil + compost + cocopeat (2:1:1), and soil + compost + charcoal husk (2: 1: 1); and AMF (without and with AMF). Results showed that there was interaction effect between AMF and composition of growing medium on percentage of stolon formed into tuber and weight of potato tubers per plant. Treatment of medium soil + compost + cocopeat (2:1:1) and the addition of AMF increased the percentage stolon formed into tubers as high as 84%, and potato tuber weight to 328 g plant. Growing medium consisted of soil + compost + cocopeat (2:1:1) increased plant height, plant dry weight, shoot root ratio, and number of potato tubers. This finding showed that AMF application combined with proper growing medium increased the the production of potato seeds.
A critical contribution on understanding the mechanism and implication of peat irreversible drying
Authors: Wardani I K , Suwardi  , Darmawan  , Sumawinata B
Published: December 2019

The term irreversible drying is known as a condition when peat soil material is dry and cannot be re-wet after an intensive drying. This condition is a result of peat soil hydrophobicity that occurs when a contact angle between peat soil particles and water is greater than 90° and is always understood to be associated with water content. However, in South Kalimantan, there was a phenomenon of irreversible drying but soil water content was still around field capacity and there was a visible coating substance on the particle surface. The purposes of this study were 1) to clarify the cause of irreversible drying in this location and 2) to show a possible effect of rock phosphate addition on the hydrophobicity’s disappearance. A hydrophobic peat soil sample was taken from the location that is cultivated for oil palm. Field observation was conducted on the peat soil that had been amended by rock phosphate. The peat soil hydrophobicity was identified by the Water Drop Penetration Time method and the surface coating substance was observed using SEM-EDS. The WDPT result shows that the peat soil was in hydrophobic condition, but the water content was still around field capacity. The results from SEM-EDS indicate that the coating substance was found as sulfate salts. The rock phosphate that had been added in the field shows a positive effect on the disappearance of the peat irreversible drying. However, the mechanism of soil properties change due to rock phosphate cannot be confirmed yet and need further investigation.
On the development of measurement procedure of particle density for peat material
Authors: Faoziah N , Iskandar  , Djajakirana G , Darmawan  , Sumawinata B
Published: December 2019

Value of particle density of tropical peat materials commonly is considered to be 1.4 g/cm3. This value was based on the measurementusing a pycnometer. However, this value would not be correct for tropical peat that has coarse material that could plug the narrow opening of the pycnometer. Hence, the use of pycnometer to measure particle density of tropical peat material has a possibility to get false values because the coarse material will inhibit the measurement process. Therefore, we are proposing the use of a three phases meter to measure particle density of tropical peat materials. The particle density value obtained by using three phases meter was around 1.8 g/cm3. The value was higher than pycnometer result due to the three phases meter could ensure the measurement of all size tropical peat material.
The Impact of slope steepness and land use type on soil properties in Cirandu Sub-Sub Catchment, Citarum Watershed
Authors: Siswanto S Y , Sule M I S
Published: December 2019

The research was conducted to investigate the relationship between topography (slope steepness) and landuse on soil physical properties. This research was conducted at Cirandu sub-cathment, Citarik Catchment Area, Citarik Sub Watershed, Upper Citarum Watershed, West Java. The study was carried out using a physiographic free survey method, which is a survey based on land physiographic appearance, and soil sampling was carried out into transect on the similarity slope without calculating the point of observation range. Soil sampling was carried onto three classes of slope and three land use type The result of the research showed that there are no effect of slope steepness and landuse on organic matter, hydraulic conductivity and erodibility. The highest erodibility value was found on the forest with 8-15% slope.
Infiltration effectiveness of Alfisols under albazia and coconut trees and in barren land in the middle part of Bogowonto Watershed, Central Java – Indonesia
Authors: Sampurno V N , Sartohadi J , Pulungan N A H J
Published: December 2019

Surface runoff is the source of soil erosion, leading to soil resources degradation in the hilly and the mountainous areas. Albazia is a common revegetation trees at the study area as a source of annual income. Coconut is a traditional plantation tree becoming a source of daily income from its sap and/or monthly income from its fruit. This study was based on field observations during 20 rainfall generated runoff. The collected research data were rainfall intensity, stemflow, throughfall, infiltration, and physico-chemical characteristics of the soil. The results show that the effective infiltration under Albazia trees, under coconut trees, and in barren land respectively 11%, 38% and -39% respectively. Physiological characteristics of Albazia and coconut which include canopies, stems, and roots have controled the soil capacity of infiltration. The barren land which is only covered by grass and bush vegetation is becoming the main source of runoff in the study area.
Effect of the conservation plants on runoff, soil erosion, and root characteristics in the volcanic areas
Authors: Saidi A , Adrinal
Published: December 2019

Research on reducing surface runoff and erosion by using vegetation method has been widely carried out. But the using of grasses plants to control erosion and landslide was not yet widely done, especially the effect of plant root parameters on reducing surface runoff and erosion. A research was carried out on volcanic soil in Experimental Station, Agriculture Faculty, Andalas University. This study was carried out from April 2018 to November 2018. It uses a 15 m x 2 m plots that was limited by brick concrete on 3 sides and the other side was used for measuring runoff and soil erosion. This experiment consisted of 4 treatments with 3 replications. The experimental units were arranged to according to a completely randomized design (CRD). Data were analyzed the variance using F test at 5 % level of significance and then continued using the Least Significance difference (LSD 0.05 if F calculated > F table. The treatments were; A = Vetiver + Simple terrace, B = Vetiver + Napier grass, C = vetiver + King grass, D = King grass + Napier grass. Observations were carried out on surface runoff, soil erosion, soil physical properties, soil shear strength, and root characteristics. Root characteristics observations using the Mwango et al (2014) method. Their parameters were root diameter, root density, root length density, root area ratio, and relative soil particles detachment rate. The field experimental results showed that combination of Napier and King grass (D) are better than another treatment to decrease surface flow and soil erosions. Between King grass + Napier grass (D), vetiver + Napier grass (B) and vetiver + King grass (C) treatments were not significantly different, exceptly with Vetiver grass + simple terrace. This statement also contribute by soil strength, and root properties at 0-30 cm depth.
Spatial analysis of hotspot data for tracing the source of annual peat fires in South Sumatera, Indonesia
Authors: Hamzah A S , Darmawan  , Sumawinata B , Suwardi  , Djajakirana G
Published: December 2019

Forest and land fires in Indonesia have become the main national and global concern for the last decade. This disaster can cause enormous losses in the economic, social and environmental sectors because it occurs almost every year. The cause of these fires was always strongly believed to be of human activities (anthropogenic). A definite description of what activities most often cause fire incidences can be approximated by pointing out the initial fires that can be than correlated with kinds of activities that ignited the fires. The initial fires can be traced from hotspot data. Therefore, this study aimed to seek the initial fire locations in South Sumatera where there are activities of both small-scale farmers and big-scale industrial plantations on peatland and the adjacent non-peat areas. Daily hotspot data (MODIS) from 2014 to 2018 with a confidence level of more than 80% of the South Sumatra wetland areas were used in this study. The result showed that the initial hotspots mostly detected on floodplains and coastal plains that are adjacent to the peatland that is called here as transitional land. The local community in these locations generally utilizes the land for rice or seasonal plant cultivation by burning the land (Sonor culture).
Financial analysis of direct application of reactive phosphate rock fertilizer on corn farming on upland acid soils
Authors: Irawan  , Kasno A , Husnain  , Samsun A
Published: December 2019

Indonesia has extensive upland acid soils, which is around 99.6 million hectares spread across Sumatera, Kalimantan and Papua Islands. The use of upland acid soils for food crops is an urgent need because of the government’s self-sufficiency target, including corn. The level of nutrient in upland acid soils is relatively low so it requires adequate input of ameliorant, inorganic and organic fertilizers to produce high corn yield. A demonstration farm of corn based on the direct application of reactive phosphate rock (RPR) fertilizer was carried out in rainy season 2018/2019 by involving three farmer groups as cooperative farmers, with an area of 50 ha in Margosari village, Metrokibang subdistrict, Lampung Timur Regency. This paper presents the results of financial analysis of corn farming at the demonstration farm area. Data was gathered from 52 farmers (43.7% of the cooperative farmers) which randomly selected as survey respondents. The results of the analysis showed that balanced fertilization using RPR as much as 1 t ha−1 as a source of P fertilizer was financially benefited to farmers. The average corn productivity of hybrid varieties reached 14.357 t ha−1 and it gave an R/C ratio of 1.8.
Spatial utilization control for supporting development acceleration: case study in South Tangerang city, Banten Indonesia
Authors: Cahyani D T , Munibah K , Mulyanto B
Published: December 2019

Spatial plan is a guideline for a country’s development containing strategic policies and spatial utilization programs. The high dynamics of space needs for development implementation impacting to the spatial uses change and raising number of spatial unsuitability. South Tangerang city, as an urban area which serves as a capital buffer zone, experiences a fairly high development intensity, that giving a development effect to some areas in economic and ecological ways. The existing land use analyses found that 21,91% of the existing land use are not suitable with the spatial plan, 55,28% suitable, and 22,81% are still in transition. The change of the land uses are dominated by trade and services area and areas which has an access to an infrastructure facilities. This development activity including infrastructure, potentialy raised spatial utilization unsuitablility. This research is about to map the land use gradations and the consistency of spatial utilization related with the development planning in South Tangerang city in order to raise the effectiveness of spatial utilization control. Detailed instrument are needed, so the Government must accelerate the preparation of Detailed Spatial Plan (RDTR).
Selecting land characteristics affecting local flash sweet potato production levels based on production indicator of consumer preference
Authors: Solihin M A , Setiawan A , Nurbaity A , Widiatmaka
Published: December 2019

Rancing sweet potato is one of preferred local flash sweet potatoes in Indonesia. The interesting thing about Rancing is on its sweetness taste that meet on common consumer’s preference. So, production indicator of Rancing should be consider the sweetness levels in addition of yield. The study aimed to selecting land characteristic affecting Rancing production levels based on combination of yield and sweetness indicator. Sampling units were research plot in actual production site in West Java. Sweet potato tuber samples were collected at harvest time, whereas the soil samples were taken by composite soil sample at each sampling unit. Rancing production indicator was measured in total sugar weight (kg ha−1). Total sugar weight was determined by multiplication of weight of yield (t ha−1) and total sugar content (%) of Rancing at harvest time at same sampling units. Selecting land characteristics were affecting Rancing production were determined using stepwise multiple discriminant analysis. Results showed that there were soil and climate properties affecting Rancing production levels. These land characteristics can be considered in determining land use requirements of Rancing.
Effect of toposequence on rice (Oryza sativa l.) by intermittent irigation in Bali
Authors: Arsana I G K D , Kariada I K
Published: December 2019

The research of toposequence effect on rice aims to study effect of toposequence on rice planting season by different way of irrigation in Yeh Ho watersheds Tabanan Bali. This research used some varieties of rice namely Mekongga, Inpari 1 and Inpari 10 Laeya. The result showed that toposequence had significant effect on milled dry paddy (GKG). Upstream toposequence able to produce rice about 6450 kg ha−1, middle was about 6460 kg ha−1 and downstream was about 7260 kg ha−1 by significantly different. Irrigation interval every eight days capable to produce 7400 kg ha−1 of rice which was 17,3% higher than continuously irrigation production about 6280 kg ha−1. Also, irrigation interval every four days can produce 6490 kg ha−1 of rice which was 12,3% higher than continuously irrigation production about 6280 kg ha−1. Varieties of Mekongga produce 6800 kg ha−1 of GKG which was 5% lower than Inpari 10 Laeya varieties, 4,1% lower than Inpari 1 varieties. Then, Inpari 1 produce 7080 kg ha−1 of GKG which was 0,89% lower than Inpari 10 Laeya. Irrigation interval every eight days capable to produce highest of GKG compared to others irrigation interval. It can be conclued that toposequence had significant different on rice production.