摘要:

The effect of finger-harrowing (FH) on weed control and yield of durum wheat (Triticum durumDesf) grown under conventional tillage (CT) or no-tillage (NT) was studied in 1995–96. Mechanical weeding—eight combinations between four tine adjustments and two treatment intensities (one or two passes)—was compared with post-emergence herbicide spraying and an unweeded control. Tine working depth was higher in CT than in NT due to lower soil dry bulk density, and increased with the theoretical aggressiveness of tine adjustments, but its correlation with short- and long-term effects on crop and weeds overall was poor, suggesting that tine adjustment was not a major factor involved. In 1995, durum wheat grain yield in FH was very low, because of high weed development in both tillage systems. In 1996, lower weed pressure resulted in FH grain yield, on average 3982 kg ha−1for CT and 2809 kg ha−1for NT, comparable with that obtained with herbicides. Durum wheat grain yield and weed biomass were much more affected by tillage system than by tine adjustment or harrowing intensity, and seemed mostly dependent on the lower crop competitive ability in NT, caused by reduced emergence, higher weed abundance and presence of aggressive weed species,Ammi majusin 1995 andLolium multiflorumin 1996. Dependence of FH effect upon soil and weed conditions encountered seasonally in the two tillage systems suggests that, in low-input durum wheat, mechanical methods alone would not always guarantee adequate weed control and grain yield.

ISSN:0144-8765    

DOI:10.1080/01448765.2000.9754850

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

In organic viticulture, downy mildew is often controlled with copper. Because copper is known to be phytotoxic and to accumulate in the soil, the replacement of copper is a major concern of organic agriculture. Here, 13 on-farm trials to evaluate potassium phosphonate as an alternative fungicide to copper are reported. Residues were determined in 53 samples of wine.

ISSN:0144-8765    

DOI:10.1080/01448765.2000.9754851

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Biodynamic (BD) agriculture is an organic farming system that relies heavily on compost as a fertilizer. Six herbal preparations are added to composting materials in order to make BD compost. Proponents claim these additions produce higher quality compost under farm conditions. In this study, BD compost preparations were applied to 3.5 t compost piles made of dairy manure and woodshaving bedding. Application of the BD preparations also requires 6 1 soil and 8 1 water; therefore control piles received the same additions of soil and water as BD compost piles, but no BD preparations. Biodynamic-treated composts maintained an average 3.4°C higher temperature throughout the eight-week active composting period, suggesting more thermophilic microbial activity and/or faster development of compost with BD treatment. Final samples were taken when active composting slowed and the piles entered a ripening stage. At the final sampling, BD-treated piles respired C02 at a 10% lower rate and had a larger ratio of dehydrogenase enzyme activity to C02 production. Microbial communities in the finished BD and control piles were differentiated by principal component analysis of microbial phospholipid fatty acids. Final samples of BD-treated composts also had 65% more nitrate than control piles. Biodynamic preparations thus effected discernible changes in compost chemical and microbial parameters.

ISSN:0144-8765    

DOI:10.1080/01448765.2000.9754852

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Soils of the groundnut(Arachis hypogaea) L. basin of Senegal are impoverished with low fertility and organic matter content. Previously, farmers maintained yields of millet (Pennisetum glaucum(L.) R. Br. and groundnut with subsidized inorganic fertilizers and fallow periods to restore soils. Fish meal or by-product in various forms is a commercial commodity worldwide, but in Senegal the non-edible portion of fish (intestines, bones, scales and gills) are often discarded after processing. A three-year study was conducted on processed fish by-products as a soil amendment for millet and groundnut productivity. Chemical analysis showed that the processed fish byproducts are high in major nutrients such as N, 5.35%; P, 4.17%; K, 0.92%; Ca, 9.77%; and Mg, 0.36%. Consequently, the application of the processed fish by-products significantly (p < 0.05) increased millet grain from 0.29 Mg ha−1in the control plot (no fish by-product) to 2.50 Mg ha−1with 6 Mg ha−1fish by-product. Millet stover yield was also increased. Groundnut yields increased (p < 0.01) from 0.23 Mg ha−1in the control plots to about 1.00 Mg ha−1with 2 Mg ha−1fish by-product. Response curves for millet and groundnut were curvilinear with the incorporated fish remains explaining 98 and 99% of variability in yields of millet and groundnut respectively. Residual effect of fish by-product after one year significantly (p < 0.05) improved yields of millet and groundnut compared with inorganic fertilizer and equalled yields of the same crops with inorganic fertilizer after two years. However, stability analysis indicated that millet yields with fish by-product were less stable (s.e. = 0.31) than yields with inorganic fertilizer (s.e. = 0.16) reflecting the non-uniformity of the by-products and processing methods across villages.

ISSN:0144-8765    

DOI:10.1080/01448765.2000.9754853

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The short-term effects of harvesting on survival and dispersal of insect predators in hay lucerne(Medicago sativaL.) were investigated in a commercial crop in Australia. Adults of two coleopterans, transverse ladybird beetle (Coccinella transversalisFabricius Coccinellidae) and pollen beetle(Dicranolaius bellulus(Guérin-Méneville) Melyridae), and one heteropteran, spined predatory shield bug (Oechalia schellembergii(Guérin-Méneville) Pentatomidae), were marked and released into lucerne strips immediately before they were cut for hay. Vacuum sampling of the stubble immediately after harvest showed that proportional mortalities were 0.16, 0.00 and 0.07 respectively. Proportions of the released individuals that were recovered alive were 0.66 for C.transversalis, 0.45 forO. schellembergiiand 0.02 forD. bellulus.The proportion of predators that were not recaptured from release areas was greatest forD. bellulus(0.80). To assess dispersal after harvest, 12 strips of lucerne were left uncut within the field in which the marked insects had been released. Intensive sweep-net sampling of these strips caught marked survivors of all three predators. The numbers of insects caught in strips declined with increasing distance from the release point. Many insect predators, therefore, survived harvesting and, if uncut refuge strips are provided, the within-field community of biological control agents is largely preserved.

ISSN:0144-8765    

DOI:10.1080/01448765.2000.9754854

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Lack of information about the specific environmental adaptation of cover crop species remains a serious constraint in the efficient design of agronomic experiments examining options for more suitable and more sustainable management of hillside farming systems in the tropics. Predictive models of crop phenology for cover crop species exist but how robust these are for legume cover crop species is largely unproven. We determined the predictive ability of phenological models, derived from glasshouse studies and driven by temperature and photoperiod, across a diverse range of cover crop genotypes and tropical hillside environments. The models were designed to predict the duration from germination to first flowering, and from first flowering to first pod maturity. Seeds of eleven legume species of cover and/or green manure crops collected from different hillside locations world-wide were sown in two groups of nurseries (tropical short-day plants in early summer and sub-tropical long-day plants in early winter) at Kabale and Namulonge in Uganda, Godavari and Lumie in Nepal, Cochabamba in Bolivia, Zamorano in Honduras, and Valenca in Brazil. Dates of sowing, first flowering and first pod maturity were taken and daily temperature data were recorded at each site. Similar observations for the same genotypes were available from independent experiments conducted at Islamabad, Pakistan, Hattiban, Nepal and at three locations in Cyprus. Model predictions were compared with field observations. The proportion of variation accounted for in the period from sowing to first pod maturity was 88% and 89% for the short-day and the long-day groups of genotypes, respectively. Likewise, the average difference from sowing to pod maturity between the model predictions and the field observations was 6.3% and 7.9% for the combined short-day species and the combined long-day species, respectively. It is clear that the model predictions, for this dataset at least, are sufficiently robust to serve as a filter for determining the environmental suitability of germplasm.

ISSN:0144-8765    

DOI:10.1080/01448765.2000.9754855

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

ISSN:0144-8765    

DOI:10.1080/01448765.2000.9754856

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

ISSN:0144-8765    

DOI:10.1080/01448765.2000.9754857

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

ISSN:0144-8765    

DOI:10.1080/01448765.2000.9754858

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

ISSN:0144-8765    

DOI:10.1080/01448765.2000.9754849

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor