Disease suppression of potting mixes amended with composted biowaste

Peat mining destroys valuable nature areas and contributes to the greenhouse effect. This warrants the search for alternatives for peat in potting mixes. Composted biowaste could provide such an alternative. An additional advantage of (partially) replacing peat by compost is the increased disease suppressiveness. In this study, nine commercial composted biowastes were tested for disease suppressiveness using the pathosystems Pythium ultimum-cucumber, Phytophthora cinnamomi-lupin and Rhizoctonia solani-carrot. Increased disease suppression was found in compost-amended potting mixes for all three pathosystems. The level of disease suppression ranged from slight stimulation of disease to strong suppression. Suppressiveness against one disease was not well correlated with that against the other diseases. The CO2 production, a measure of general microbial activity, was the parameter most strongly correlated with the level of disease suppression. Wetsieving the biowaste with tap water over a 4-mm sieve prior to composting yielded a compost with an 2.4-fold increase in organic matter and a twofold decrease in EC and Cl--concentration of the compost. The latter reductions allow for an increase of the amount of peat that can be replaced by compost. A linear relation was found between the amount of compost added to the potting mix and the level of disease suppression indicating the potential for increasing disease suppressiveness of potting mixes by replacing peat by high-quality composted biowastes

Handbook for Composting and Compost Use in Organic Horticulture

Compost, as a product of recycling processes, can be a very appropriate input material for organic farming, provided the composting process is well-managed, the input materials are free of contaminants, and the resulting product is applied according to the system’s ecological needs. Compost is a very important input material for organic greenhouse production. Organic greenhouse production may vary in the level of intensity, but it is generally a system with high turnover rates of organic matter, high inputs of both nutrients and energy, and high production levels. Compost is used as an important source of organic matter and nutrients in greenhouse horticulture, and is an important component of growing media for nurseries. Compost plays an important role in building a resilient farming system, by providing both the energy sources and the nutrients to sustain soil biodiversity

Testing the paradox of enrichment along a land use gradient in a multitrophic aboveground and belowground community

In the light of ongoing land use changes, it is important to understand how multitrophic communities perform at different land use intensities. The paradox of enrichment predicts that fertilization leads to destabilization and extinction of predator-prey systems. We tested this prediction for a land use intensity gradient from natural to highly fertilized agricultural ecosystems. We included multiple aboveground and belowground trophic levels and land use-dependent searching efficiencies of insects. To overcome logistic constraints of field experiments, we used a successfully validated simulation model to investigate plant responses to removal of herbivores and their enemies. Consistent with our predictions, instability measured by herbivore-induced plant mortality increased with increasing land use intensity. Simultaneously, the balance between herbivores and natural enemies turned increasingly towards herbivore dominance and natural enemy failure. Under natural conditions, there were more frequently significant effects of belowground herbivores and their natural enemies on plant performance, whereas there were more aboveground effects in agroecosystems. This result was partly due to the “boom-bust” behavior of the shoot herbivore population. Plant responses to herbivore or natural enemy removal were much more abrupt than the imposed smooth land use intensity gradient. This may be due to the presence of multiple trophic levels aboveground and belowground. Our model suggests that destabilization and extinction are more likely to occur in agroecosystems than in natural communities, but the shape of the relationship is nonlinear under the influence of multiple trophic interactions.

An Overview of Phytosanitary Risk Aspects of Composting by Organic Farmers

Usage of compost in agriculture always brings about the risk of introducing plant pathogens. By proper composting, resulting in high temperatures during the thermophilic phase, compost can be applied safely. Organic farmers often prefer to compost organic residues themselves. The advantage of such an approach is that no material of foreign origin is introduced, but a drawback is the smaller scale of composting, which brings about greater phytosanitary risks. These risks can be dealt with by increasing the composting duration and by proper turning of the compost heap. If only organic residues from farms are composted, this usually results in low-quality composts because of the low lignin contents. Therefore, addition of materials that are high in lignin, such as wood chips, is advisable. In conclusion, on-farm composting is well possible from a phytosanitary point of view, but the farmer has to be aware of the factors that affect the phytosanitation of organic waste and the quality of the compost

Maatregelen in de landbouw tegen bodempathogenen : De beheersing van bodempathogenen is niet hetzelfde als management van bodemkwaliteit

Uit een recent verschenen rapport1 valt op te maken dat er geen generieke manier is om bodempathogenen aan te pakken. Het helpt om zorg te dragen voor optimale groeiomstandigheden, maar dit beschermt onvoldoende.1 Ook een goede biologische bodemkwaliteit, voor zover deze al helder is gedefinieerd, leidt niet automatisch tot effectieve ziektewering. De werkelijkheid is complexer en lichten we toe

Inleiding: Wat is plantgezondheid en waarom is het belangrijk?

Planten, ze zijn overal. Veruit het meeste land op aarde is bedekt met een groene laag van bossen, oerwouden of graslanden, en ook de oceanen zitten vol met primi-tieve planten, algen. Zonder planten kunnen wij niet leven; zonder planten zou er nauwelijks zuur-stof zijn en geen voedsel. Het bladgroen dat plan-ten hun groene kleur geeft, is de krachtige motor. Aangedreven door zonlicht maakt dat zuurstof uit water en suikers uit kooldioxide (CO2). Dit unieke proces heet fotosynthese. De plant zet de suikers om in eiwitten, vetten en zetmeel en slaat die op in vruchten, granen, peulen en knollen, die dieren en mensen vaak weer opeten. Planten staan dus aan de basis van de voedselpiramide