Ngom et al J. Appl. Biosci. 2013. Caractéristiques écologiques du peuplement ligneux de la réserve de biosphère du Ferlo, Sénégal ABSTRACT Objectives : This study aims to characterize the various structural parameters of the woody vegetation in Ferlo Biosphere Reserve (FBR). Methods and Results: In 2011 measurement of dendrometric characteristics of trees and an inventory of the woody flora was carried out in 110 plots of 900 m² each. The total specific richness was 49 species and the Journal of Applied Biosciences 65:5008 -5023 ISSN 1997-5902 Ngom et al J. Appl. Biosci. 2013. Caractéristiques écologiques du peuplement ligneux de la réserve de biosphère du Ferlo, Sénégal 5009 average of the specific richness was 5.8 species / plot. The analysis of centesimal frequencies showed that Guiera senegalensis (75%), Combretum glutinosum (65.5%), Boscia senegalensis (63.6%) and Pterocarpus lucens (60.9%) are the most common species. Tree density is higher in the central area (392 ind / ha) while the basal area and the recovery are higher in the buffer zone with respectively 9.17 m²/ha and 43%. Concerning the structure, the woody trees have a relatively high proportion of seedlings. In fact, over 90% of trees surveyed have heights between 0 and 6 m and circumference between 10 and 100 cm, which shows the importance of the shrub layer in the FBR. With regard to the ecological importance, three species are distinguished : Pterocarpus lucens (18%), Guiera senegalensis (16%) and Combretum glutinosum (13%). The rate of regeneration of plant population is 72% in the FBR. It is twice higher in the core area (79%) which is less anthropized than the buffer zone (36%) and the transition zone (39%). Guiera senegalensis has the highest potential of regeneration with a specific regeneration index more than 62%. Conclusion and applicability of the results: These results demonstrate the potential of the FBR to ensure the dual role of biodiversity conservation and provision of ecosystem services to local communities.

This document synthesizes information about the warm season cover crop sunn hemp. The question-and-answer format addresses frequently asked questions for growers with answers that summarize the growing body of sunn hemp research. The information is provided so that growers in Florida can learn about up-to-date cultivation and management options for sunn hemp as well as better understand its practical uses. This document is a follow-up to the following: Wang, Qingren, Yuncong Li, Waldemar Klassen, and Edward Hanlon. 2015. “Sunn Hemp : A Promising Cover Crop in Florida”. EDIS 2015 (7), 4. https://doi.org/10.32473/edis-tr003-2015. Wang, K., and Robert McSorley. 2004. “Management of Nematodes and Soil Fertility With Sunn Hemp Cover Crop”. EDIS 2004 (18). https://journals.flvc.org/edis/article/view/114109.

Potato (Solanum tuberosum L.) has low phosphorus (P) use efficiency as compared with other vegetable crops. This study was conducted at two commercial chipping potato farms (A and B) in Northeast Florida to evaluate different P rates for potato production. Plot size was 0.62 and 0.49 hectares for Farms A and B, respectively. The total trial area was 13.32 hectares per growing season for three consecutive years from 2018 to 2020. The randomized complete block design (RCBD) was employed with four replications per P rate. The chipping potato variety, ‘Atlantic’ was cultivated with three P rates: 0, 24.5, and 48.9 kg P ha−1 in 2018, and 12.2, 24.5, and 48.9 kg P ha−1 in 2019 and 2020. The soil of Farm A contained 497 mg kg−1 Mehlich-3 extractable P and 946 mg kg−1 aluminum (Al), and that of Farm B had 220 mg kg−1 Mehlich-3 extractable P and 253 mg kg−1 Al. The results showed that a P rate of 48.9 kg P ha−1 significantly improved tuber yield as compared to 0 in 2018 or 12.2 kg P ha−1 in 2019 and 2020. Application of 48.9 kg P ha−1 fertilizer P significantly increased the soil P level in 2018 and 2020, while the application of 24.5 kg P ha−1 fertilizer P increased the soil P level significantly in 2018 only. Tubers with 48.9 kg P ha−1 showed significantly lower external quality issues than 0 or 12.2 and 24.5 kg P ha−1. However, there were no significant differences in specific gravity, internal tuber quality, and tuber size among the different P rates. The tuber yield data show that potato plants grown on soil with high legacy P still require approximately 50 kg ha−1 P application for sustainable potato production in the area. This high P requirement results from the combination of high concentrations of active metals (Al and iron (Fe)) and a decrease in pH of one unit in the growing season. New P-fertilization programs with post-plant applications rather than with pre-plant application are urgently needed for minimizing P-immobilization by Al and Fe and improving P-use efficiency for potato production in the state.

Expansion of cultivated lands and field management impacts greenhouse gas (GHG) emissions from agriculture soils. Soils naturally cycle GHGs and can be sources or sinks depending on physical and chemical properties affected by cultivation and management status. We looked at how cultivation history influences GHG emissions from subtropical soils. We measured CO2, N2O, and CH4 fluxes, and soil properties from newly converted and continuously cultivated lands during the summer rainy season in calcareous soils from south Florida. Newly converted soils had more soil organic matter (OM), more moisture, higher porosity, and lower bulk density, leading to more GHG emissions compared to historically cultivated soils. Although more nutrients make newly converted lands more desirable for cultivation, conversion of new areas for agriculture was shown to release more GHGs than cultivated lands. Our data suggest that GHG emissions from agricultural soils may decrease over time with continued cultivation.

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