Microbe-plant growing media interactions modulate the effectiveness of bacterial amendments on lettuce performance inside a plant factory with artificial lighting

There is a need for plant growing media that can support a beneficial microbial root environment to ensure that optimal plant growth properties can be achieved. We investigated the effect of five rhizosphere bacterial community inocula (BCI S1-5) that were collected at three open field organic farms and two soilless farms on the performance of lettuce (Lactuca sativa L.). The lettuce plants were grown in ten different plant growing media (M1-10) composed of 60% v/v peat (black peat or white peat), 20% v/v other organics (coir pith or wood fiber), 10% v/v composted materials (composted bark or green waste compost) and 10% v/v inorganic materials (perlite or sand), and one commercial plant growing medium inside a plant factory with artificial lighting. Fractional factorial design of experiments analysis revealed that the bacterial community inoculum, plant growing medium composition, and their interaction determine plant performance. The impact of bacterial amendments on the plant phenotype relied on the bacterial source. For example, S3 treatment significantly increased lettuce shoot fresh weight (+57%), lettuce head area (+29%), root fresh weight (+53%), and NO3-content (+53%), while S1 treatment significantly increased lettuce shoot dry weight (+15%), total phenolic content (+65%), and decreased NO3-content (-67%). However, the effectiveness of S3 and S1 treatment depended on plant growing medium composition. Principal component analysis revealed that shoot fresh weight, lettuce head area, root fresh weight, and shoot dry weight were the dominant parameters contributing to the variation in the interactions. The dominant treatments were S3-M8, S1-M7, S2-M4, the commercial plant growing medium, S1-M2, and S3-M10. Proper selection of plant growing medium composition is critical for the efficacy of bacterial amendments and achieving optimal plant performance inside a plant factory with artificial lighting

Onderbouwen van een methodiek voor de systematische monitoring van koolstofvoorraden in landbouwbodems

Gedurende het laatste decennium kende het onderzoek naar organische koolstofvoorraden in de bodem (BOC-voorraden) een sterke opgang in Europa en ook in Vlaanderen. Deze hernieuwde interesse in organische stof kwam voornamelijk voort uit de ratificatie van het Kyoto-protocol dat een mogelijkheid voorzag om CO2 ‘sinks’ in te brengen in nationale broeikasgasemissiebalansen. Eerder onderzoek in België toonde een sterk verlies aan BOC aan gedurende de jaren ‘90. Bovendien bleek het potentieel om koolstof op te slaan in de bodem beperkt te zijn voor de intensieve Vlaamse landbouw. Dit maakt onze landbouwbodems kwetsbaar voor verder BOC-verlies en de daaraan verbonden bodemdegradatie. Bijgevolg dienen BOC-voorraden verder opgevolgd te worden om de gevolgen van het huidige en toekomstige landbouwbeleid op de bodemkwaliteit te evalueren. Hoewel België op wereldvlak over de grootste dichtheid aan BOC-data beschikt, is een verdere opvolging van BOC-voorraden momenteel niet georganiseerd in Vlaanderen. Dit onderzoeksproject behelst in hoofdzaak het opstellen van een methodiek voor de opvolging van BOC-voorraden in Vlaanderen. De studie werd onderverdeeld in vier werkpakketen: - WP 1: bespreking van de reeds bestaande BOC-monitoringsystemen in Europa - WP 2: bespreking van de methodologische aspecten bij de bepaling van BOC-voorraden - WP 3: inschatting van de ruimtelijke en temporele variabiliteit van BOC-voorraden in Vlaamse landbouwbodems - WP 4: opstellen van een bemonsteringsstrategie voor de Vlaamse landbouwbodem

Evaluatie en waardering van de archeologische sites Rooiveld-Papenvijvers Oostkamp (West-Vlaanderen) Juli-November 2008

Dit rapport werd ingediend bij het agentschap samen met een aantal afzonderlijke digitale bijlagen. Een aantal van deze bijlagen zijn niet inbegrepen in dit pdf document en zijn niet online beschikbaar. Sommige bijlagen (grondplannen, fotos, spoorbeschrijvingen, enz.) kunnen van belang zijn voor een betere lezing en interpretatie van dit rapport. Indien u deze bijlagen wenst te raadplegen kan u daarvoor contact opnemen met: [email protected]

Biochar amendments change microbial community structure and activity and nutrient dynamics in loamy soils

Increasing levels of greenhouse gases in the atmosphere have lead to the search for new technologies to mitigate climate change. The use of biochar contributes to stable organic C sequesteration into soils. However the addition of biochar to soils may also change physico-chemical soil properties, microbial activity, nutrient dynamics and consequently soil productivity (Glaser et al., 2002). An incubation experiment was conducted over 98 days into two silty loamy soils, with different management histories, arable land and recently converted grassland to which four different types of biochar were added. Biochar, prepared from either poultry litter or pine chips and pyrolized at both 400 °C and 500 °C, was added at a rate of 20 Mg.ha-1. Every two weeks pH, mineral N (NO3-, NH4+) and plant available phosphorus (PAP) was determined. Additionally soil microbial parameters, such as phospholipid fatty acid analysis (PLFA) for the microbial community structure, microbial biomass (by the fumigation-extraction method) and enzyme activities were measured. Due to the biochar amendments nutrient cycles in these loamy soils were affected. Depending on the charring temperature and the biomass feedstock, N dynamics differed significantly among the treatments. Higher charring temperatures slowed the rate of N mineralization down. In pine wood biochar amended soils even an immobilization of N was observed. PAP increased in poultry litter amended soils, also charring temperature increase the amount of PAP. At the end of the incubation the activity of dehydrogenase, an enzyme that plays a role in the microbial oxidation of organic matter was for both soils highest in the P500 biochar treatment. Microbial biomass C (MBC) decreased during the incubation. While in the arable land only the 400°C biochar applications made the MBC increase, in the converted grasslands all biochar types (and especially the 500°C biochars) induced a MBC increase. PLFA analysis, followed by Fisher’s Canonical Discriminant Analysis (CDA) revealed that pyrolysis temperature had a higher influence on the microbial community structure than the biochar feedstock. Due to biochar amendments there was a decrease of arbuscular mycorrhizal fungi (AMF) in both soil types, however in arable land this decrease was more pronounced than in converted grassland. We conclude that the addition of biochar to Flemish loamy soils has a tremendous effect on microbial community and nutrient dynamics. Especially nitrate leaching and the accompanied environmental harm may be prevented by adding woody biochar types to these soils. Soil biological parameters are changed due to biochar amendments, however the microbial response is dependent on the biochar feedstock; pyrolysis conditions and the soil management