Soil Bacterial and Fungal Communities Response Differently to Bombax Ceiba (Malvaceae) in a Traditional Agroforestry System

Background Agroforestry system is one of promising directions for developing sustainable agriculture because the intercropping of crops and trees may facilitate resource cycling and avoid soil degradation. Bombax ceiba (Malvaceae), a tall tree with red flowers blooming in Spring, is traditionally planted in rice paddies in tropical Asia, while the roles of B. ceiba in the agroecosystem remain unexplored.Methods In this paper, we investigated and assessed spatiotemporal variations of soil nutrient contents and soil bacterial and fungal communities along the distance gradients to B. ceiba during three reproductive stages of rice, i.e. booting, heading, mature, in a typical Bombax-dominated rice paddy on Hainan Island, South China.Results B. ceiba in rice paddy could improve the soil nutrient conditions, particularly available K and soil organic carbons. The relative abundance of Chloroflexi and Ascomycota increased while Actinobacteria decreased along the distance gradient to B. ceiba. In addition, the relative abundance of Firmicutes was highest at harvesting stage of rice, while Acidobacteria was richer in the early reproductive stage of rice. Soil potassium content was the principal driver in shaping soil bacterial diversity and composition, while fungal community was mainly affected by soil nitrogen.Conclusions Our results provide evidences for positive influences of B. ceiba on biotic and abiotic traits of rice paddy soils and thus lend supports to the ecological basis of this tropical Asian endemic traditional Agroforestry system, which could increase resource cycling and paddy stability and have the potential to reduce carbon emission.

Effects of source location on the pozolannic properties of Rice Husk Ash (Rha) and strength properties of concrete

This paper presents the effects of variability in the chemical and elemental composition of Rice Husk Ash (RHA) sourced from four (4) different locations on Tensile Properties of Concrete. RHA is an agricultural waste gotten from rice mills after removal of rice paddy for food and burnt in open air or under controlled processes. RHA is found to be pozzolanic and can be used to partially replace cement to enhance the strength and quality of concrete. The different sources where RHA was gotten are; Ogoja, Abakaliki, Adani and Adikpo in Nigeria. It is discovered that the pozolanic properties of RHA varies based on their source location. Samples from Ogoja where found to have the highest pozzolanic properties followed by Abakaliki, Adani, and Adikpo, their silica content was found to be 84.55, 76.3, 70.12, 70.11, respectively. RHA was used to replace cement in concrete at 5, 10,15,20,25 and 30%. The compressive strength was determined and the values are as follows; And the compressive strength values at 28 days was found to be in the range of 37-42N/mm2 at 5%RHA, 35-39.5N/mm2 at 10%RHA, 30-34.5N/mm2 at 15%RHA, 27-29N/mm2 at 20%RHA, 22-25.6N/mm2 at 25% RHA and 21-24N/mm2 at 30% RHA compared to the controlled sample with a strength value of 42.64N/mm2. Cylindrical columns concrete of size 100mm diameter by 200mm long were moulded and stored in water for 28 days before testing for tensile splitting strength. The values determined from the split tensile test are as follows; 2.1-3.1N/mm2 at 5%RHA, 2.1-2.5N/mm2 at 10% RHA, 1.8-2.10 N/mm2 at 15% RHA, 1.2-1.7 N/mm2 at 20%RHA, 1.1-1.3 N/mm2 at 25% RHA and 0.62-0.9 N/mm2 at 30% RHA while the results of the controlled sample is 3.1 N/mm2.From the results above it can be deduced that source location influences the chemical properties of RHA strength characteristics of the Concrete with RHA as partial replacement.

ANALISI DAMPAK BENDUNGAN PANDANDURI TERHADAP USAHATANI PADI SAWAH DI KECAMATAN SAKRA BARAT KABUPATEN LOMBOK TIMUR

This study aims to determine the impact of the Pandan Duri dam on changes in the Crop Index (IP) and changes in the productivity level of rice paddy farming in West Sakra District, East Lombok Regency. The method in this research is descriptive, data collection is done by survey technique. Determination of the number of samples as many as 30 people is done by sampling quota and taking farmers in each village is done by proportional random sampling and determining the village as a sample is done by purposive sampling. The results showed that: 1) The total planting index (IP) of lowland rice before the Pandan Duri dam in West Sakra District was 1.39 and after 2.12. This means that the existence of the Pandan Duri dam can have an impact on the difference in the Crop Index (IP) of lowland rice farming in Sakra District and, 2) The average productivity of rice before the Pandan Duri dam in West Sakra District was 49,682 Kw/Ha while after the Pandan Duri dam was 57,267 Kw/Ha and there was a significant difference at the alpha 5% (0,05) level.or in the other word, that the existence of Pandan Duri development has real/significant impact on the productivity of lowland rice farming in West Sakra District, East Lombok Regency

Fractionation of stable carbon isotopes during acetate consumption by methanogenic and sulfidogenic microbial communities in rice paddy soils and lake sediments

Acetate is an important intermediate during the degradation of organic matter in anoxic flooded soils and sediments. Acetate is disproportionated to CH4 and CO2 by methanogenic or is oxidized to CO2 by sulfate-reducing microorganisms. These reactions result in carbon isotope fractionation, depending on the microbial species and their particular carbon metabolism. To learn more about the magnitude of the isotopic enrichment factors (ε) involved, acetate conversion to CH4 and CO2 was measured in anoxic paddy soils from Vercelli (Italy) and the International Rice Research Institute (IRRI, the Philippines) and in anoxic lake sediments from the northeastern and the southwestern basins of Lake Fuchskuhle (Germany). Acetate consumption was measured using samples of paddy soil or lake sediment suspended in water or in phosphate buffer (pH 7.0), both in the absence and presence of sulfate (gypsum), and of methyl fluoride (CH3F), an inhibitor of aceticlastic methanogenesis. Under methanogenic conditions, values of εac for acetate consumption were always in a range of −21 ‰ to −17 ‰ but higher in the lake sediment from the southwestern basin (−11 ‰). Under sulfidogenic conditions εac values tended to be slightly lower (−26 ‰ to −19 ‰), especially when aceticlastic methanogenesis was inhibited. Again, εac in the lake sediment of the southwestern basin was higher (−18 ‰ to −14 ‰). Determination of εCH4 from the accumulation of 13C in CH4 resulted in much lower values (−37 ‰ to −27 ‰) than from the depletion of 13C in acetate (−21 ‰ to −17 ‰ ), especially when acetate degradation was measured in buffer suspensions. The microbial communities were characterized by sequencing the bacterial 16S rRNA (ribosomal ribonucleic acid) genes as well as the methanogenic mcrA and sulfidogenic dsrB genes. The microbial communities were quite different between lake sediments and paddy soils but were similar in the sediments of the two lake basins and in the soils from Vercelli and the IRRI, and they were similar after preincubation without and with addition of sulfate (gypsum). The different microbial compositions could hardly serve for the prediction of the magnitude of enrichment factors.