Manutenção do solo

A mobilização do solo é uma prática ancestral. Tem servido propósitos tão nobres e determinantes para a humanidade como a preparação do solo para as sementeiras, a cobertura das sementes e a eliminação das ervas daninhas ou plantas infestantes. Em olival tradicional conduzido em sequeiro, o solo é mobilizado visando um objectivo principal - destruir as infestantes que competem com as oliveiras pela água e pelos nutrientes. As infestantes têm de ser eliminadas, de contrário o olival enfraquece pela invasão da vegetação espontânea

Abundance and diversity of soil arthropods in olive grove ecosystem (Portugal): effect of pitfall trap type

Soil arthropod biodiversity is an indicator of soil quality and can be studied using pitfall trapping. In this research, olive grove edaphic fauna was assessed at different sampling dates by comparing two different diameters (7 and 9 cm) and three different contents (empty, water and preservative) of pitfall traps in order to determine which type of pitfall trap is more efficient. Considering all pitfall trap types and sampling times, a total of 12,937 individual edaphic arthropods belonging to 11 taxa were recovered. Smaller traps with preservative collected significantly more individuals than the other pitfalls tested. Larger and empty traps collected significantly more spiders and traps with preservative collected more beetles. Smaller and empty traps collected fewer individuals than the other trap types. Both Shannon’s diversity and Pielou’s evenness indexes were higher in the larger and empty traps and richness was higher in the smaller traps filled with water. The study of myrmecocenosis was emphasised because olive grove soil fauna was numerically dominated by Formicidae (56.6% of all organisms captured) belonging to 12 genera and 24 species; Tapinoma nigerrimum, Messor barbarus, Cataglyphis hispanicus, Tetramorium semilaeve, Cataglyphis ibericus, Messor bouvieri and Camponotus cruentatus were the most abundant ant species. Traps with preservative reached the highest accumulation of species for a small number of pitfalls when compared with the other pitfalls studied and a sampling effort of 20 samples is apparently sufficient to sample the greater part of the ant species of the olive grove. From this study, it seems that traps with preservative are the best choice to use in further studies concerning the epiedaphic fauna of the olive grove

Tuber yield and leaf mineral composition of Jerusalem artichoke (Helianthus tuberosus L.) grown under different cropping practices

Jerusalem artichoke is commonly grown for its edible tubers, livestock feed and as an ornamental. The possibility of growing Jerusalem artichoke for energetic purposes has aroused scientific interest in this species. Despite several studies that have already been done in the last few decades, many aspects of the cropping practice are still relatively unknown. During the growing seasons of 2004-2006 field trials were carried out in NE Portugal. During the experimental period different cropping conditions were imposed, regarding irrigation, planting density, nitrogen fertilization and propagation method. The crop was irrigated in 2004 and 2005 and grown in rain-fed conditions in 2006. The planting densities were 7 plants m-2 in 2004, 2, 3 and 4 plants m-2 in 2005 and 2 and 4 plants m-2 in 2006. Botanical seed was used in 2005 and seed-tubers in all the three years. In 2005, 0 and 100 kg N ha-1 was combined in a factorial design with the planting densities. Maximum tuber dry matter yield (18.4 Mg ha-1) was recorded in 2005 in the plots where 100 kg N ha-1, 2 plants m-2 and seed-tubers were combined. The best planting density was 2 plants m-2 in irrigated (2005) and rain-fed (2006) conditions. Nitrogen significantly increased tuber yield in 2005 only when seed-tubers were used. Averaged across N fertilization rates and planting densities mean tuber yields were 12.8 and 6.9 Mg ha-1 for seed-tuber and botanical-seed, respectively. Leaf mineral composition was little affected by cropping practices, as well as chlorophyll SPAD readings