Acid Upland Soils Research Articles

The Effects of Soil Acidity and Aluminium on the Root Systems and Shoot Growth of Lotus pedunculatus and Lupinus polyphyllus.

Lotus pedunculatus (lotus) and Lupinus polyphyllus (Russell lupin) persist in the upland grasslands of New Zealand, where soil acidity and associated aluminium (Al) toxicity impede conventional pasture legumes. This experiment investigated the response of lotus and Russell lupin to soil acidity and Al. The species were sown in 20 cm tall 1.2 L pots of acidic upland soil. A mass of 4.5 or 6.7 g lime (CaCO3)/L was added to either the top or bottom or both soil horizons (0-9 cm and 9-18 cm), resulting in six treatments across six randomised blocks in a glasshouse. The soil pH was 4.4, 4.9, and 5.4; the exchangeable Al concentrations were 24, 2.5, and 1.5 mg/kg for 0, 4.5, and 6.7 g lime/L. At 16 weeks post-sowing, the plants were divided into shoots and roots at 0-9 cm and 9-18 cm. Root morphology, shoot and root dry matter (DM), shoot nitrogen (N), and nodulation were measured. The total plant DM and shoot-to-root DM ratio were higher, and the shoot %N was lower for the lotus plants than the Russell lupin plants for the various lime rates (13.2 vs. 2.9 g plant-1, 5.6 vs. 1.6, and 2.4 vs. 3.3%, p < 0.05). No response to lime in terms of total DM or total root morphology parameters was exhibited in either species (p > 0.05). Root morphology adjustments in response to acidity between soil horizons were not observed. The results indicated that lotus and Russell lupin are tolerant to high soil acidity (pH 4.4-5.4) and exchangeable Al (1.5-24 mg kg-1), highlighting their considerable adaptation to grasslands with acidic soils.

Effect of phosphorus management on yield and economics under direct seeded rice (Oryza sativa) and blackgram (Vigna mungo) intercropping in a rainfed acidic upland soil

A field experiment was conducted during rainy (kharif) season of 2019 at ICAR-National Rice Research Institute (NRRI), Central Rainfed Upland Rice Research Station (CRURRS), Hazaribagh, Jharkhand to study the effect of phosphorus management on productivity and profitability under direct seeded rice (Oryza sativa L.) (DSR) and blackgram [Vigna mungo (L.) Hepper] intercropping in rainfed acidic upland soil. The experiment was laid-out in a split-plot design comprised 4 methods of cropping, viz. Sole DSR; Sole blackgram; DSR + blackgram (4:1); and DSR + blackgram (4:2) allotted to main-plots and 4 phosphorus management practices, viz. P control (P0 ); Recommended dose of phosphorus (RDP) @17.5 kg P/ha; 50% RDP + phosphate solubilizing bacteria (PSB) @500 g/ha + arbuscular mycorrhiza fungi (AMF) @12.5 kg/ha; and 25% lime requirement (LR) + PSB + AMF in sub-plots. Experiment consisted of 16 treatment combinations, replicated thrice. The rice variety ‘Sahabhagi’ and blackgram variety ‘Uttara’ were used. Among the cropping systems, the highest grain yield was recorded in sole rice (3.84 t/ha) and sole blackgram (1.14 t/ha) which was significantly higher than yields under intercropping in both the ratios. Gross (`96,879/ha) and net returns (`70,603/ha) of sole blackgram were significantly higher than other cropping systems and followed by DSR + blackgram (4:2). Net benefit:cost (B:C) of sole blackgram was maximum (`2.69) and lowest in sole rice (`1.01). Among phosphorus management treatments, 50% RDP + PSB + AMF gave significantly higher net return (`49,440) and net benefit:cost (`1.68). Application of 100% RDP and 25% LR + PSB + AMF gave at par returns and net benefit:cost. It may be suggested that under rainfed uplands of eastern India, farmers may adopt either sole blackgram or intercropping of rice and blackgram in 4:2 over sole DSR for higher productivity and monetary returns. For better phosphorus management in soil they should inoculate PSB and AM fungi along with 50% RDP at the time of sowing.

Active microbial taxa preferentially assimilate inorganic nitrogen in acidic upland soils using a 15N-DNA-SIP approach

Soil endogenous nitrogen is an essential source of crop nitrogen supply. Nitrogen assimilation is a vital transformation process that maintains nitrogen availability and promotes the mineralization of endogenous organic nitrogen in acidic soils. However, the dominant microbial populations that assimilate NH4+ and NO3− in acidic upland soils were unknown, and their response to long-term fertilization remained unclear. In this study, 15N-labeled NH4+ and NO3− were added to acidic upland soils characterized by long-term (32 years) differentiation in organic matter inputs. Glucose was added to facilitate nitrogen assimilation, and a nitrification inhibitor (dicyandiamide, DCD) was added to distinguish the contribution of NH4+ and NO3− assimilation. Results showed that soil inorganic N assimilation mainly occurred in the first week after inorganic N addition. Soil net inorganic N assimilation rates were 0.006–0.42 mg N kg−1 d−1 in the NH4+, NO3− and NH4++DCD treatments. The analysis of 15N-DNA-based stable isotope probing (SIP) found that the majority of inorganic N assimilation in our soils was conducted by a limited number of active microbial taxa, which accounted for 1.4%–2.0% of the entire bacterial community and 15.7%–28.8% of the fungal community. The dominant bacteria governing inorganic N assimilation in acidic upland soils included Bacillus, Burkholderia–Caballeronia–Paraburkholderia and Micrococcaceae. The primary fungi included Penicillium, Chaetomium, Aspergillus, and Fusarium. No obvious bias was detected in nitrogen assimilation rates and the dominant microbial taxa for NH4+-N and NO3−-N. Compared with unfertilized soil, long-term organic matter input decreased the dominating N assimilating microbial taxa. These findings demonstrate the feasibility of 15N-DNA-SIP technology in soil nitrogen cycling research and suggest the importance of active microbial taxa in acidic agricultural soil nitrogen retention and loss.

Long-Term Successive Seasonal Application of Rice Straw-Derived Biochar Improves the Acidity and Fertility of Red Soil in Southern China

Soil acidity is a crop production problem of increasing concern in acid red soil. The potential of biochar as a soil amendment/for soil acid management in agricultural fields is a recently recognized yet underutilized technology. Related evidence is currently limited to short-term indoor experiments with one-time BC applications and no crop cultivation, yet the degree to which soil acidity may be impacted by the biochar aging process on long-time scale remains unclear. To evaluate the effects of successive seasonal applications of rice straw-derived biochar (BC) on acidity and fertility of soil, a five-year outdoor column trial was conducted using wheat-millet rotated acidic upland soils from the south of China. BC was applied to the top 0–15 cm of soil at the rates of 0 (BC0), 2.25 (BCL), and 22.5 (BCM) Mg ha−1 with an identical dose of NPK fertilizers at the beginning of each crop season. Our results showed that the wheat-millet biomass yield gradually decreased over five rotation cycles in BC0 without BC application. In contrast, after five rotations, BCM led to an increase in the total wheat/millet grain yield by 138%, and the straw yield increased by 253% compared to the control. The cumulative above-ground nutrient uptake of P, K, Ca, Na, and Mg in BCM also increased by 139%, 171%, 129%, 182%, and 71%, respectively, compared to that in the control. This positive effect was attributed to the increase in soil pH (3.29 units), cation exchange capacity (5.66 cmol kg−1), soil available P (241%), K (513%), Ca (245%), Mg (265%), exchange base (3.36 cmol kg−1), base saturation percentage (65.7%), and decrease in the exchangeable acidity, especially exchangeable Al3+ content (&lt;0.1 cmol kg−1). Our results demonstrated that rice straw-derived BC application to soil at 22.5 t ha−1 was found to be highly consistent in decreasing soil acidity and reducing soluble and exchangeable Al3+, indicating its higher ameliorating capacity in the south of China in the long run.

Enhancing chemical properties and maize yield through dolomite application on rock phosphate-amended oxisol

Improving soil quality is vital so plants can adapt to climate change. Indonesia's acid soils cover about 147.5 million hectares, and are generally acidic, with low levels of calcium and magnesium, and high levels of aluminum. This study aims to study the effect of dolomite application on acid upland soils that have been applied with rock phosphate to improve soil chemical properties and increase maize yields. The research was conducted in Jati Agung using a randomized block design with 5 treatments and 5 replications. The treatment consisted of 5 application levels of dolomite: 0, 500, 1000, 1500, and 2000 kg ha-1. The size of the experimental plot was 10 m x 10 m. Hybrid maize varieties were used as indicators. The results showed that applying dolomite increased soil pH, Ca, Mg, and K levels and decreased exchangeable and Al saturation. It also increases plant height, maize yield, and biomass. The implication of this study is that the application of dolomite 1000 kg ha-1 after rock phosphate is applied can improve soil chemical properties in acid soils.

Fungal dominance of gross nitrogen mineralisation in an acidic upland soil amended with organic fertiliser

AbstractFungi typically prevail in acidic soils and have a stronger preference for complex organic compounds than bacteria. Thus, we hypothesized that fungi would play a more important role in gross nitrogen (N) transformation in acidic soil than bacteria, and the dominance of fungi on gross N transformations in acidic soil would increase following complex organic inputs. Herein, we determined bacterial and fungal contributions to gross N transformation processes using a 15N tracing approach combined with selective inhibition in an acidic upland soil under aerobic conditions. Streptomycin was used as the bacterial inhibitor and cycloheximide as the fungal inhibitor. Our results showed that bacteria appeared to dominate autotrophic nitrification but fungi were also involved, and both bacteria and fungi contributed to the gross rate of dissimilatory nitrate reduction to ammonium (NH4+). When rape seed cake was added to the soil, fungi dominated gross N mineralisation and played an important role in gross NH4+ immobilisation. Our results suggest that the addition of organic fertiliser into acidic upland soil can enhance the contribution of fungi to the mineralisation‐immobilisation turnover of N.Highlights Bacterial and fungal contributions to gross N transformation rates were quantified. Bacteria dominated autotrophic nitrification in acidic upland soil. Fungi dominated gross N mineralisation following organic fertiliser addition. Adding complex carbon to acidic soil boosts fungal‐mediated N transformations.

Productivity of ‘Robusta’ coffee trees in response to different pruning systems in an acid upland soil

Productivity of ‘Robusta’ coffee trees in response to different pruning systems in an acid upland soil

Soil Water Responses to Wood Ash Addition to Acidic Upland Soils: Implications for Combatting Calcium Decline in Lakes

Soil Water Responses to Wood Ash Addition to Acidic Upland Soils: Implications for Combatting Calcium Decline in Lakes

Comparison study of growth and yield of three soybean varieties on acid upland soil of South Lampung

Lampung is mostly occupied by marginal acid upland soils. However, applying of suitable technology innovations could improve the soybean productivity in this marginal land. Until now, only a few field studies have been conducted on the adaptability of new soybean varieties in acid upland soils of Lampung. Therefore, present study’s objectives were to compare the agronomic performance and the yield of three soybean varieties on an acid upland soil of South Lampung. As the treatments, the three soybean varieties were Anjasmoro, Grobogan, and Dering 1. The research was set in a Completely Randomized Design with four replications. The results showed that in general, based on the agronomic performance, the Anjasmoro variety was more adaptable compared with Grobogan and Dering 1 variety. This might be related to the number of effective nodules in the rooting system of Anjasmoro variety which was higher than that of Grobogan and Dering 1 varieties. In addition, the Anjasmoro variety had the highest yield as 2.60 t ha−1 than that of the Grobogan and Dering 1 varieties as 2.33 and 1.99 t ha−1, respectively.

Organic matter management for sustainable productivity of corn-groundnut cropping pattern on acid upland soils

This study aims to conduct the organic management that sustain productivity of corn-groundnut sequential cropping on acid upland soil in South Kalimantan, Indonesia. Tanah Laut Regency is the target area for this conservation farming system. Furthermore, these areas havebeen identified potentially for food crop development The experiment was conducted Bumi Asih villages, Panyipatan sub district, Tanah Laut, South Kalimantan provinces. In 1994/1995 WS until 1995 DS. These area as a ultisol soil type and transmgiration areas. Randomized Complete Block Desgind (RCBD) with four replication, and plot size 10 m x 20 m. There were Six treatment consisted of O1(No Farm Yard Manure/FYM), organic matter remains incorporated in to the soil + Fertilizer 60 kg N + 35 kg P2O5 per ha; O2 (1 t FYM organic matter remains incorporated in to the soil + 120 kg N + 70 kg P2O5/ha); O3 (All organic matter remains incorporaed in to the soil + 2,5 t FYM/ha); O4 (as Treatment O3 + 5 t FYM/ha); O5 (as treatment O3 + 10 t FYM/ha) and O6 (as treatment O3 + 20 t FYM/ha). Corn cv Arjuna was planted with row spacing 200 cm x 20 cm; and intercrops with Groundnut cv Pelanduk with row spacing 25 cm x 20 cm during two seasons planting. Data were colect i.e some physical soil properties such as soil moisture; soil hardness; some chemical soil properties such as soil pH, Org-C; plant nutrient such plant nutrient content such as leaf of N; P; Ca and Mg contents.. Growth parameter i.e shoot dry weight and yield of corn and groundnut. Data colected were analyzed by Variant analyzis. Diferently among treatment were analyzed by DMRT.0.05.. ...The results showed that the increase ins oil pH due to highC-organd some nutrient contents such as N, P, Ca and P inleaf of corn were significantly affected during the last seasons by organic amendment. In terms of cultivation, organic matter increased the infestation of weeds.. The organic management with the highest application (20 tonnes.ha-1 FYM) in every season yielded up to four – five times for corn and 0.65 – 1.28 for groundnut compared to control/farmer practices (1.175 t dry seed/ha).

Methane-Oxidizing Communities in Lichen-Dominated Forested Tundra Are Composed Exclusively of High-Affinity USCα Methanotrophs.

Upland soils of tundra function as a constant sink for atmospheric CH4 but the identity of methane oxidizers in these soils remains poorly understood. Methane uptake rates of −0.4 to −0.6 mg CH4-C m−2 day−1 were determined by the static chamber method in a mildly acidic upland soil of the lichen-dominated forested tundra, North Siberia, Russia. The maximal CH4 oxidation activity was localized in an organic surface soil layer underlying the lichen cover. Molecular identification of methanotrophic bacteria based on retrieval of the pmoA gene revealed Upland Soil Cluster Alpha (USCα) as the only detectable methanotroph group. Quantification of these pmoA gene fragments by means of specific qPCR assay detected ~107 pmoA gene copies g−1 dry soil. The pmoA diversity was represented by seven closely related phylotypes; the most abundant phylotype displayed 97.5% identity to pmoA of Candidatus Methyloaffinis lahnbergensis. Further analysis of prokaryote diversity in this soil did not reveal 16S rRNA gene fragments from well-studied methanotrophs of the order Methylococcales and the family Methylocystaceae. The largest group of reads (~4% of all bacterial 16S rRNA gene fragments) that could potentially belong to methanotrophs was classified as uncultivated Beijerinckiaceae bacteria. These reads displayed 96–100 and 95–98% sequence similarity to 16S rRNA gene of Candidatus Methyloaffinis lahnbergensis and “Methylocapsa gorgona” MG08, respectively, and were represented by eight species-level operational taxonomic units (OTUs), two of which were highly abundant. These identification results characterize subarctic upland soils, which are exposed to atmospheric methane concentrations only, as a unique habitat colonized mostly by USCα methanotrophs.

Contrasting effects of different pH‐raising materials on N2O emissions in acidic upland soils

AbstractAcidic soils, occupying ca. 40% of the world's arable soils, often need to be managed (e.g., to raise their pH and to improve crop productivity); however, the environmental impact of raising soil pH is often difficult to assess. Increasing soil pH stimulates the reduction of N2O to N2, thus lowering N2O emissions associated with denitrification, but can also increase autotrophic nitrification rates and related N2O emission. Using a 15N tracing technique, we provide process‐based insights into the effects of two acid‐neutralizing materials (quicklime [CaO] vs. pig manure) on N2O emissions in an acidified upland soil that had experienced excessive N application. Without pH adjustments we found that N2O emissions, stimulated by supply of reactive N, were related to denitrification‐ and heterotrophic nitrification‐derived N2O emissions, whereas autotrophic nitrification‐derived N2O emissions declined with decreasing soil pH. These effects were reversed by increasing soil pH via liming. However, increasing the soil pH via application of pig manure significantly increased soil N2O emissions from both nitrification and denitrification. Our study highlights that pH‐amelioration practices may enhance N2O emissions depending on the type of material applied to the soil. Therefore, both pH remediation and greenhouse gas mitigation options need to be considered together to avoid adverse environmental effects. The effect of different acid‐neutralizing materials on soil N2O emissions should be incorporated into ecosystem models to better estimate global N2O emissions when pH amelioration is practised.Highlights Enhanced N2O emission by N input was from denitrification and heterotrophic nitrification. Chemical N input and liming have reversible effects on N2O emission. Soil N2O emission was decreased by liming but increased by animal manure input. Careful consideration of pH raising substrates is needed to avoid adverse effects.

Amelioration of Acid Upland to Increase Soil Productivity and Soybean Yield

The space between young rubber plants can be utilized for growing soybean. The aim of this study was to quantify the effectiveness of some soil ameliorants applied in combination with a reduced dosage of NPK fertilizer on soil properties and soybean yield. in a young rubber and soybean intercropped system on acid upland soil. The study was conducted in East Lampung Indonesia from April to July 2013. The plots were designed in a split-plot with three replications. The main plots were the level of NPK fertilizer recommendation dosage (100% and 75%). The subplots were soil ameliorants. The results showed that a 25% reduction of NPK did not significantly affect the soil properties and soybean yield when applied with soil ameliorants. Application of dolomite 2 t/ha and Biochar SP50 2.5 t/ha reduced soil exchangeable Al content by 25.3% and 20.8% respectively. Dolomite was the most effective to increase soil pH, whilst Biochar SP50 provided the highest soil available water pores (15.25% vol.). Soybean gave better yield when the soil was treated with dolomite, Biochar SP50, and organic fertilizer plus. Reduction in soil acidity and improvement of soil available water pores most likely were responsible factors to give better yields of soybean planted on acid soil.

Assessing the viability of soil successive straw biochar amendment based on a five-year column trial with six different soils: Views from crop production, carbon sequestration and net ecosystem economic benefits

Converting straw to biochar (BC) followed by successive application to soil has been increasingly suggested as a multi-win approach for soil fertility improvement, carbon (C) sequestration and efficient disposal of straw residues in intensive cropping agroecosystems. However, different soil types response differently in terms of crop growth and non-CO2 greenhouse gas (GHG) emissions after BC application. Furthermore, few studies have comprehensively evaluated the net global warming potential (GWP) and net ecosystem economic benefits (NEEB) after long-term BC incorporation across representative soil types in China. A five-year outdoor column experiment was conducted using three rice-wheat rotated paddy soils and three millet-wheat rotated upland soils developed from different parent materials. Rice straw BC application rates of 0, 2.25 and 11.3 Mg ha−1 were used in each crop season with identical doses of NPK fertilizers. Compared with the no BC controls, BC significantly boosted crop growth, enhanced C sequestration, and decreased cumulative N2O and CH4 emissions in all six soils over five rotation cycles. The response of the upland soils to BC was better in terms of crop growth and N2O mitigation, whereas the soil organic carbon (SOC) increment and CH4 mitigation were less effective compared with the paddy soils. Net GWP decreased 0.6–19 fold after BC application; however, given the low trade price of CO2 (0.21 × 103 CNY Mg−1), only a small contribution was made in terms of C costs to the NEEB. The BC-induced NEEB was mainly dependent on grain yield gains and BC costs. These findings highlight that widespread adoption of successive straw BC application to farmland requires an increase in crop yield and substantial lowering of the BC cost regardless of the soil type. From the standpoints of agronomics, environment and economics, acid upland soil shows most potential in terms of BC application.

Effect of Integrated Nutrient Use on the Energetics and Economics of Sugarcane Production in Negros, Philippines

Sound management of soil nutrients is necessary in improving the productivity of sugarcane monoculture. Different fertilizers have advantages and limitations, thus, it is imperative to frame out a strategy for the judicious combination of these nutrient sources. This study determined the effect of using organic amendments and microbial inoculant on the energetics and economics of sugarcane production under acid upland soil. Field experiment involving twelve treatments using 'Phil 2004-1011' sugarcane variety was carried in acid Typic Hapludand soil. The recommended N rate (RRN) was reduced to 75, 50 and 25% with subsequent application of mudpress to satisfy the full N recommendation. Bagasse ash and microbial inoculant were used to supplement the nutrient sources. Reducing the recommended N rate with subsequent application of mudpress, bagasse ash and microbial inoculant produced the highest cane and sugar yield. Application of 25% RRN from inorganic fertilizer + 75% RRN from mudpress + bagasse ash + microbial inoculant had the highest energy efficiency and cane yield per joule. Utilization of 50% RRN IF: 50% RRN MP + BA + MI produced the most sugar yield per joule. Better return on investment and benefit-cost ratio were obtained from the application of 50% RRN from inorganic fertilizer: 50% RRN from mudpress. In conclusion, the combined use of inorganic, organic, and biofertilizers can improve cane yield and energy efficiency. Integrated use of inorganic and organic fertilizers can increase economic efficiency.

Evaluation of Udaipur Rock Phosphate as Phosphorus Fertilizer in Soybean (Glycine max L. Merrill) Grown on Acid Upland Soils of Nagaland

Evaluation of Udaipur Rock Phosphate as Phosphorus Fertilizer in Soybean (<i>Glycine max</i> L. Merrill) Grown on Acid Upland Soils of Nagaland

Nitrification Activity and Autotrophic Nitrifiers in Long-term Fertilized Acidic Upland Soils

Soil microcosm incubation, molecular ecology techniques including denaturing gradient gel electrophoresis and Illumina MiSeq high-throughput sequencing, and bioinformatics analysis were carried out to investigate the effect of long-term fertilization with chemical fertilizers (NPK) and organic manure (OM) on soil nitrification activity and the autotrophic nitrifying communities in acidic upland soils. No fertilization soil (CK) was the control. Relationships between soil nitrification activities, autotrophic nitrifying communities, and soil characteristics were further evaluated. Long-term fertilization significantly increased the soil organic carbon and inorganic nitrogen contents. Fertilization with organic manure significantly increased soil pH and total nitrogen contents, but decreased soil C/N. Autotrophic nitrification dominated soil nitrification, and accounted for 73.60%-85.32% of total nitrification. Fertilization significantly increased soil autotrophic nitrification activity and the highest value was observed in the OM soil. During the microcosm incubation, the absolute abundances of amoA genes and the relative abundances of 16S rRNA genes of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in the OM soil significantly increased. The relative abundances of 16S rRNA genes of the AOA greatly increased in both CK and NPK soils. These results suggested the remarkable activity of AOA in the three soils (the predominant population was Nitrososphaera,>99.30%) and implied that AOB was active in the OM soil (the predominant population was Nitrosospira,>99.99%). We also found the activity of nitrite-oxidizing bacteria (NOB) in the OM soil, and the predominant population was Nitrospira (>96.69%). Stepwise regression analysis demonstrated that soil autotrophic nitrification activity was significantly affected by soil total nitrogen content, whereas the abundances of archaeal and bacterial amoA genes were significantly affected by soil organic carbon content and soil pH, respectively. We also found significant positive correlation between the relative abundance of Nitrososphaera and soil nitrate content and a negative correlation between the relative abundance of Nitrosospira and Nitrospira with soil C/N. Overall, our results showed that long-term fertilization greatly increased soil nitrification activity and altered the autotrophic nitrifying communities in acidic upland soils. Soil autotrophic nitrification activity was significantly stimulated by soil total nitrogen content. The Nitrososphaera group played a critical role in nitrification of acidic upland soils. The increased soil pH and decreased soil C/N stimulated the growth of Nitrosospira.

Pemanfaatan Pembenah Tanah dan Mikroba Pelarut P untuk Meningkatkan Efektivitas Pupuk NPK pada Usahatani Jagung di Lahan Kering Masam

Maize farming on an acid upland soil generally gives high priority to the use of chemical/NPK fertilizers. Application of organic soil amendments and P (phosphate) solubilizing microbes in maize farming on an acid upland soil were expected to substitute the use of NPK fertilizer without reducing the yields. The research aims was to study the effectiveness of biochar, cow dunk and P solubilizing microbes applications to substitute NPK fertilizers application as shown on the growth and productivity of maize (var. P 27), Relatively Agronomic Effectivenes (RAE) and B/C ratio. The research was conducted from January to June 2014 on an acid upland soil at Tamanbogo Experimental Farm, East Lampung District using randomized block design with four replications. The treatment consisted of Control (T1), NPK fertilizer recommendation dose (T2); biochar 5 t/ha + 50% of NPK recommendation dose (T3); P solubilizing microbes 5 g/plant + 50% of NPK recommendation dose (T4); Cow dunk 5 t/ha + 50% of NPK recommendation dose (T5) and biochar 5 t/ha + P solubilizing microbes of 5 g/plant + cow dunk 5 t/ha + 50% of NPK recommendation dose (T6). The results showed that the combination of NPK fertilizer at a dose of 50% of NPK recommendation + cow dunk at a dose of 5 t/ha (T5), showed the best growth and productivity of P27 maize with B/C ratio of 2.10.

Perakitan Varietas Padi Adaptif pada Tanah dengan Kandungan Fosfor Suboptimum

Phosphorus deficiency is common in rice cultivated soils and particularly acting as a limiting factor in the acid sulfate and acid upland soils. Improved variety adapted to low soil-P condition is needed to reduce the need of P fertilizer and to increase rice yield. A study was conducted on the application of modified bulk selection method in rice breeding to develop lines adapted to low soil-P condition. The materials used in the study were two populations of F3 generation derived from crosses of IR6008023/Bernas Prima and Gampai/Progol. The materials were planted on P sub-optimum condition at Muara Experiment Station, Bogor, West Java, to obtain F4 and F5 population, selected using modified bulk method. The F5 population were planted on two environment conditions, namely on P optimum (36 kg/ha P2O5) and on P sub-optimum (without P fertilizer) to obtain F6 population. A total of 40 lines from each population were selected, so that 160 F6 lines were obtained. The F6 lines were evaluated on P+ and P- conditions, using augmented design. Result showed that selection for lines adapted to P- should be done on P- condition, whereas for those adapted to P+ could be done on either P+ or P- condition. Lines selected for P- were different from those selected for P+, and some lines selected for both P- and P+ felt at different yield ranks. It was concluded that modified bulk method followed by line selection was effective to develop breeding lines adapted to P- or P+. For P-, the modified bulk and line selection should be conducted in P-, whereas for P+, the modified bulk could be planted on P+ or P-, but the line selection should be conducted on P+ condition.

Microbial community composition and methanotroph diversity of a subarctic wetland in Russia

This study assessed the microbial diversity, activity, and composition of methane-oxidizing communities of a subarctic wetland in Russia,with mosaic cover of Sphagnum mosses and lichens of the genera Cladonia and Cetraria. Potential methane-oxidizing activity of peat sampled from lichen-dominated wetland sites was higher than that in the sites dominated by Sphagnum mosses. In peat from lichendominated sites, major bacterial groups identified by high-throughput sequencing of the 16S rRNA genes were the Acidobacteria (35.4-41.2% of total 16S rRNA gene reads), Alphaproteobacteria (19.1-24.2%), Gammaproteobacteria (7.9-11.1%), Actinobacteria (5.5-13.2%), Planctomycetes (7.2-9.5%), and Verrucomicrobia (5.1-9.5%). The distinctive feature of this community was high proportion of Subdivision 2 Acidobacteria, which are not char- acteristic for boreal Sphagnum peat bogs. Methanotrophic community composition was determined by mo- lecular analysis of the pmoA gene encoding particulate methane monooxygenase. Most (-80%) of all pmoA gene fragments revealed in peat from lichen-dominated sites belonged to the phylogenetic lineage represented by a microaerobic spiral-shaped methanotroph, "Candidatus Methylospira mobilis." Members of the genus Methylocystis, which are typical inhabitants of boreal Sphagnum peat bogs, represented only a minor group of indigenous methanotrophs. The specific feature of a methanotrophic community in peat from lichen-dominated sites was the presence of uncultivated USCa (Upland Soil Cluster alpha) methanotrophs, which are typical for acidic upland soils showing atmospheric methane oxidation. The methanotrophic community composition in lichen-dominated sites of a tundra wetland, therefore, was markedly different from that in bo- real Sphagnum peat bogs.