Agriculture is the main source of soil degradation processes in Bulgaria. Therefore, soil improvement is an important task. The possibilities for using composted either municipal waste or residues from biogas production for soil improvement in Bulgaria, suggested by the development of INEMAD (Improvement of Nutrient and Energy Management through Anaerobic Digestion) project, should be assessed and popularized. The advantages and disadvantages should be analysed and discussed. This paper uses the results of two previously published papers by AUP within the framework of INEMAD where the possibilities for production and sale of compost from municipal waste and digestate from biogas by anaerobic digestion of animal manure are discussed.
The possibilities for biogas production in Bulgaria as well as the potential for use of digestate as fertilizer are discussed. At present these options are not yet feasible for Bulgaria because of the high prices of anaerobic digestion plant and the insufficient quantities of animal manure. Advantages of waste processing are multiple, on one hand the processing of municipal waste produces compost of organic origin and can be used as a soil improver to recover nutrients and improve structure while at the same time this allows reducing the area of dunghills, unpleasant smell, and Greenhouse Gas emissions.
We report on twelve new records of ants species for the fauna in Asir region: Camponotus aegyptiacus, Camponotus sericeus, Camponotus xerxes, Cataglyphis bicolor, Cataglyphis fortis, Cataglyphis niger, Lepisiota opaciventris, Paratrechina longicornis, Crematogaster aegyptiaca, Crematogaster senegalensis, Monomorium carbonarium, and Monomorium salomonis. Genera like Cataglyphis, Camponotus, Crematogaster and Messor gradually dominate the ant fauna and are represented by a maximum number of endemic species with Myrmicinae accounting for the most numerous species followed by Formicinae. The maximum relative abundance and distribution of ant species in Asir province was observed in the Formicinae (Cataglyphis bicolor) and in the Myrmicinae (Messor ebeninus).
The DIN:DIP atomic ratio (N/P) considered optimal for phytoplankton growth is 16:1 (Redfield ratio). Significant deviations from 14 to low N/P ratio might indicate potential nitrogen limitation, the ratio between 14 and 16 indicates both nitrogen and phosphorus co-limitation, whereas from 16 to high N/P ratios indicates potential phosphorus limitation of phytoplankton primary production. This might affect the biological state of the ecosystem, in particular the phytoplankton biomass, species composition and food web dynamics. NO3- and PO43-concetrations in surface waters in six station samples were measured monthly by using spectrophotometer UV-VIS, whereas total Chl a was measured using flourometric method, from May - October 2011 and from June - October 2012. The data are converted on molar concentration (NO3-N and PO4-P) in order to calculate N/P ratios. The comparison of N/P ratios from 2011 to 2012 in Durres Bay, results in both N and P co-limitation for 2011 and N limitation of primary production in 2012. Comparing N:P ratio in Durres Bay to Southern Adriatic Sea for both 2011 and 2012, resulted in N limitation for Durres Bay and both N and P co-limitation of primary production in open waters. There is a strong positive relationship between primary production (total Chl a) and nitrogen in coastal waters and a moderate positive relationship of primary production and N/P ratio in coastal waters of Durres Bay.
Aims: Seed size, shape and colour intensity were compared in castor bean (Ricinus communis L.) grown in the field in twelve locations corresponding to four climatic regions in Tunisia.
Study Design: Seeds were obtained from plants grown in the field in twelve locations corresponding to four climatic regions in Tunisia.
Place and Duration of Study: Samples were taken in summer 2014 from plants growing spontaneously.
Methodology: Size is estimated as the area of the seed images. Shape is measured by the roundness and J index that gives the percent of similarity of the figure plane of a seed with an ellipse. Colour is measured as gray intensity in seed images.
Results: Among the parameters indicating seed shape, roundness varied more than J index. Values of J index were superior, thus J index describes better than roundness the shape of Ricinus communis seeds. Seed size and colour presented higher variation than magnitudes concerning shape indicating that shape is more conserved in Ricinuscommunis seeds, than size or colour.
Conclusion: Differences in size and shape were found among the climatic regions. Reduced size and J index values were observed together with increased values of roundness in seeds obtained from the population grown in the dessert.
Earthworms which inhabit soils and litter layers in agro-ecosystems play significant roles that regulate soil ecosystem services supporting agriculture. Through their feeding, burrowing and casting activities, earthworms redistribute organic material within the soil, increases soil penetrability, and influence soil organic matter decomposition and nutrient cycling. These activities modify plant root distribution, increase soil microbial activity and influence the supply of plant nutrients. Because earthworms respond quickly to land use changes, farm management practices affect their diversity, abundance and biomasses. While cultivation and use of acidic fertilizers and chemicals reduce earthworm numbers, management practices that enhance the supply of earthworm food such as fertilization and manure application increase their numbers. This article reviews the beneficial earthworm facilitated biotic interactions that enhance nutrient use efficiency in agro-ecosystems. First, earthworm identification, distribution, and ecology together with factors that determine their populations in agro-ecosystems are discussed. It shows that agricultural practices affect earthworms directly and that farm management can be manipulated to encourage practices that favour earthworms. Secondly, beneficial biotic initiated ecosystem services resulting from earthworm activities are presented highlighting the significant roles they play in influencing soil processes. Finally, the review ends with recommendations for future research. Overall, this review shows that earthworms are an important resource to be managed for nutrient use efficiency in agro-ecosystems. It also demonstrates the need for further research that links the physical, chemical and biological effects of earthworm activities to plant nutrient supply. It is necessary to develop suitable farm management practices that optimise these beneficial roles.