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Ferralsols correspond to the red and yellow soils that are common in the tropics. They are deeply weathered but physical fertility is high because they exhibit a strong microgranular structure whose origin is still actively debated. In the present study, we looked for evidence of the biological origin of the structure resulting from soil fauna activity. We present results recorded with Brazilian Ferralsols developed under native vegetation. It was found that the Ferralsols studied exhibit morphological features related to the activity of social insects. We showed the presence of potassium 2:1 clays originating from the saprolite in the microaggregates of all the Ferralsols studied. These 2:1 clays were earlier discussed as markers of long-term termite activity. This highlights the threat that weighs on the physical fertility of these soils, and more broadly on the water cycle in the tropical regions concerned, if intensive agriculture reduces the soil fauna biodiversity, as indicated by several studies., (© 2023. The Author(s).)

A growing concern on the deleterious effects of chemical inputs to the environment has been on the rise from the excessive use of chemical inputs leading to soil and water pollution, destruction to fauna and microbial communities, reduced soil fertility and increased crop disease susceptibility. In the Great Mekong Region (GMR), a large majority of the population relies on agriculture and faces severe challenges including decline in soil fertility, increased pests and diseases, leading to lower ecosystem productivity. In this region, over-dependence on chemical fertilizers also continues to impact negatively on soil health and the wider ecosystem. Agroecological practices, and beneficial microorganisms in particular, offer an affordable and sustainable alternative to mineral inputs for improved plant nutrition and soil health for optimal crop performance and sustainable production. Biofertilizers are a key component in integrated nutrient management as well as for increased economic benefits from reduced expenditure on chemical fertilizers, holistically leading to sustainable agriculture. To cope with the need for biofertilizer adoption for sustainable agricultural production, the countries in the GMR are putting efforts in promoting development and use of biofertilizers and making them available to farmers at affordable costs. Despite these efforts, farmers continue to use chemical fertilizers at high rates with the hope of increased yields instead of taking advantage of microbial products capable of providing plant nutrients while restoring or improving soil health. This study explored the current agricultural practices in the six countries in the GMR (China, Vietnam, Myanmar, Thailand, Cambodia and Lao PDR), the critical need for sustainable agroecological practices with a special emphasis on biofertilizers. We highlighted the current status, distribution, adoption and gaps of biofertilizer production in the GMR, in order to obtain an insight on the nature of biofertilizers, efficacy and production standards, adoption or lack of biofertilizers in the GMR., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Intensive monoculture coffee farms quickly expanded in Yunnan Province in the 1990's and 2000's. In 2012, local authorities in Pu'er and Xishuangbanna Prefectures, the main coffee producing centre in the province, initiated a large-scale conversion program of these farms towards coffee-agroforestry systems to promote "ecologically-friendly coffee". Shade tree inventories and household interviews were conducted in these two prefectures to characterize coffee farms and the Local Ecological Knowledge (LEK) of farmers on the provision of ecosystem services by associated tree species. This study on newly emerging coffee farming systems revealed a high level of tree species diversity at both farm and landscape levels despite the previous dominance of intensive coffee monoculture and the large-scale distribution of a limited number of shade tree species by the government. 162 tree species were encountered during farm inventories, out of which the community of coffee farmers was able to rank 30 against 9 ecosystem services and disservices. This study reveals that this LEK is a type of hybrid knowledge that still relies mostly on traditional knowledge of tree species combined with experience acquired from newly-implemented coffee-agroforestry practices. This study also pointed out knowledge gaps regarding the impact of mature trees on coffee yield, coffee quality and pest control. The participatory approach resulted in the identification of non-promoted species with a high potential to provide locally relevant ecosystem services in coffee-agroforestry systems. These results lead to the upgrade of an online tool (www.shadetreeadvice.org) which allows extension services generating lists of recommended shade tree species tailored to the local ecological context and individual farmers' needs. This tool will benefit farmers' livelihood, support landscape health and contribute to the sustainability of the emerging Yunnan coffee agriculture sector., Competing Interests: The authors have declared that no competing interests exist.

Rubber plantations have expanded rapidly over the past 20 years in tropical Asia and their impacts on regional ecosystems have garnered much concern. While much attention has been given to the negative impacts on aboveground diversity and function, the belowground bacterial soil community has received much less attention. Here, we investigated the community composition and diversity of soil bacteria of rubber plantations on Hainan Island in south China. The goals of the study were to describe changes in bacterial compositions and diversity across seasons. We found that seasonality defined by differences in rainfall amount strongly influenced bacterial communities. At both the Phylum and Family levels, we found significant differences in the total number of taxa, as well as the composition of the community as a function of season. Diversity of soil samples in the dry-rainy season was highest of three seasons, suggesting that bacterial structure was more sensitive in alternate periods of season. Diversity in the rainy season was substantial lower than in dry season. Results from a redundancy analysis showed that seasonal changes explained the largest part (31.9%) of the total variance of bacterial community composition. In conclusion, seasonal change had the greatest influence on bacterial communities, which overshadowed the effects of soil nutrient as well as other factors, and controls the bacterial communities in soils of RP in tropical region of Hainan., (Copyright © 2018 Elsevier B.V. All rights reserved.)

In agroforestry systems, shade trees strongly affect the physiology of the undergrown crop. However, a major paradigm is that the reduction in absorbed photosynthetically active radiation is, to a certain extent, compensated by an increase in light-use efficiency, thereby reducing the difference in net primary productivity between shaded and non-shaded plants. Due to the large spatial heterogeneity in agroforestry systems and the lack of appropriate tools, the combined effects of such variables have seldom been analysed, even though they may help understand physiological processes underlying yield dynamics. In this study, we monitored net primary productivity, during two years, on scales ranging from individual coffee plants to the entire plot. Absorbed radiation was mapped with a 3D model (MAESPA). Light-use efficiency and net assimilation rate were derived for each coffee plant individually. We found that although irradiance was reduced by 60% below crowns of shade trees, coffee light-use efficiency increased by 50%, leaving net primary productivity fairly stable across all shade levels. Variability of aboveground net primary productivity of coffee plants was caused primarily by the age of the plants and by intraspecific competition among them (drivers usually overlooked in the agroforestry literature) rather than by the presence of shade trees., (© 2017 John Wiley & Sons Ltd.)