摘要:

Soil and plant samples were taken from tropical fruit tree plantations, temperate fruit tree orchards and vegetable gardens grown using organic agricultural methods in Tenerife. Micronutrients Cu, Fe, Mn, and Zn were determined. The micronutrient content of most soils was found to fall within the normal range reported in the literature. Mn was present at low levels in the foliage of many plants, and a negative correlation between foliar Mn and soil organic matter content was observed in avocado and banana plantations. Consequently, maximum levels of soil organic matter content are established for avocado and banana. Cu, Fe, and Zn were also deficient in leaves of some plants.

ISSN:0144-8765    

DOI:10.1080/01448765.1996.9754771

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The present study was performed to elucidate if microbial activity, fungal abundance, and distribution ofPenicilliumandFusariumcan be used as bioindicators to characterize organically cultivated soils. The experimental approach was to study a potential long-term development following transition to organic farming at four farms that had been cultivated organically for 2, 8, 11, and 31 years, respectively. Sampling was performed four times in two crops (winter wheat and leys with a mixture of grass and leguminosae). The importance of the crop was clearly demonstrated in the form of a significantly higher microbial activity in the ley soils than in the wheat soils. However, the wheat soils yielded the most consistent results and thus seem better suited for studies of the long-term development of a bioindicator. The farms were chosen carefully in an attempt to minimize the variations that will always be present when studying different, commercially run farms. These variations are caused by differences in e.g. soil type, soil management, fertilizer practice, and crop rotation and development. Bearing this in mind, the results showed that the abundance of the mainly soil-borne penicillia was significantly higher at the ‘oldest’ organically cultivated farm than at the other localities, indicating a temporal development during later years following transition to organic farming. The abundance ofFusariumwas more variable at the genus level, but some of the species seem very promising as bioindicators, especiallyF. solaniandF. equiseti, but alsoF. culmorumandF. tabacinum.The results also indicate a temporal development in species richness ofFusariumduring the first years following transition.

ISSN:0144-8765    

DOI:10.1080/01448765.1996.9754772

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

In Portugal, strawberries are a key crop for the organic farming market. In 1990 and 1991Frankliniella occidentalis(Pergande) (Thysanoptera: Thripidae), the western flower thrips (WFT), was a major pest of strawberries in the Algarve. In 1993, the predatorOrius laevigatus(Fieber) (Heteroptera: Anthocoridae), a common naturally occurring species in Portugal, was experimentally released in strawberry plantings. Numbers of thrips per flower were lower in cages where theOriuswere released. In one of the cages whereO. laevigatuswas released there was also an appreciable growth of the composit weedChamaemelum mixtum(L.). The later produced large amounts of pollen and there was a lower thrips populations and a higherOriuspopulation in this plot, which happened after the weed flowering. It is not clear if this thrips reduction was caused by the increase ofO. laevigatus, as a result of feeding on the weed pollen, or by a similar transfer of thrips to theCompositaealso attracted by their pollen. A knowledge of the role of composit weeds in the reduction of thrips populations on strawberries would be very useful.

ISSN:0144-8765    

DOI:10.1080/01448765.1996.9754773

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

In Sri Lanka soil erosion is listed as the main environmental problem related to land. Mulching is an effective agronomic method of soil and water conservation if suitable material can be found. The objective of this study was to evaluate three types of coconut fibre matting for soil and water conservation in an Ultisol of Sri Lanka. This was carried out using erosion plots and soya bean as the reference crop. The results showed that coconut fibre matting reduced run-off and soil loss significantly. Soil loss reduced from 18.2 fha in no mulch plots to 0.7 t/ha in mulched plots during the 3.5 month growing season. Closely woven coconut fibre matting was the most effective as it was dense and covered the total land surface. The soil moisture depletion was less in mulched plots during the longest dry period due to increased infiltration and less evaporation. Soil temperature was reduced by 4°C when mulched with coconut fibre matting and the diurnal temperature variation also decreased. The carbon nitrogen (C:N) ratio of coconut fibre matting was very high when compared to a commonly used green manure species, showing its low decomposition rate. The dry matter production and seed yield of soya bean was significantly higher in mulched plots. With the long lasting characteristics combined with biodegradability, these materials hold great potential for long term soil erosion control.

ISSN:0144-8765    

DOI:10.1080/01448765.1996.9754774

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Changes in understorey management which accompany a shift to organic production potentially affect water and nutrient relationships for apple trees. Here we report field trials from a biological production orchard established at Winchmore, Canterbury, New Zealand in 1989 which involved a study of the changes in nutrient status of soil and of apple trees within red clover, ryegrass and mixed herb ley understories. These changes were assessed by soil, leaf and fruit analysis and related to differences in fruit production, tree growth and fruit quality. Soil and leaf nutrient levels increased with additions of nitrogen and potassium in composts and mulches. Nitrogen levels changed with both herbage (main treatment) and mow management (sub treatment) and were higher in trees grown with legumes in the understorey than in trees grown with a ryegrass understorey.

ISSN:0144-8765    

DOI:10.1080/01448765.1996.9754775

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Crop yields of cereals, carrots, beetroots and potatoes from 28 different field plot and pot experiments (on a site near Marburg/Germany) were compared to determine the influence of the biodynamic preparations 500 and 501 on yields. Under generally low yields the preparations tended to increase the yields. When the yields reach a medium level this positive effect was smaller. At higher yield levels preparations tended to lower yields. For the yield effect of the preparations 500 and 501 (= Y) and the yield levels in the untreated control (= X) a significant linear regression could be calculated: Y = 4.497—0.181 X (r = −0.615; α < 0.01%). In another experiment with spring wheat conducted for 9 years in Darmstadt/Germany the application of all eight biodynamic preparations modified yields similarly, but only at a high fertilization level. In this treatment the effects followed a significant linear regression Y = 28.930—0.87 X (r = −0.767; α = 1.59%). Yields in the untreated control varied from 1.6 to 5 t/ha. These effects have previously been discussed as a normalization of yields or as a compensation of a non-optimal nutrient supply. A new model is suggested here based on the regressions of preparation effects and yield levels.

ISSN:0144-8765    

DOI:10.1080/01448765.1996.9754776

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

ISSN:0144-8765    

DOI:10.1080/01448765.1996.9754777

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

ISSN:0144-8765    

DOI:10.1080/01448765.1996.9754778

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

ISSN:0144-8765    

DOI:10.1080/01448765.1996.9754779

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

ISSN:0144-8765    

DOI:10.1080/01448765.1996.9754770

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor