摘要:

Traditional approaches to agricultural science present a number of barriers to increasing our understanding of sustainable agriculture. Logical positivist and reductionist methods limit the information that can be obtained from complex biological systems, and institutional forces help to prevent scientists from exploring comprehensive and new directions that do not fit the predominant paradigms. A diverse range of political and institutional strategies for supporting research in sustainable agriculture is proposed.

ISSN:0144-8765    

DOI:10.1080/01448765.1989.9754518

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The experiment investigated the effect of intercropping plantains with 2,500, 5,000 and 10,000 melons/ha on delayed weeding for 3, 5 and 7 months respectively after planting. The yield of melons decreased with increased population. Intercropping plantains with 5,000 melons/ha suppressed weed growth for 7 months and significantly enhanced plantain establishment growth and yield. At 2,500 melons/ha, weeding could be delayed for only 3 months after planting beyond which weed competition reduced plantain growth and yield. Planting melons at high density checked weed growth for 7 months but reduced plantain establishment, retarded the growth and reduced the yield.

ISSN:0144-8765    

DOI:10.1080/01448765.1989.9754519

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A study was performed to examine the influence of ‘organic’ and ‘conventional’ farming on the number and composition of saprophytic soil fungi. The fields of the organic farm had been cultivated according to the principles of Steiner (1963) for 32 years. The soils were similar as to climatic conditions, soil type and vegetation. Soil samples were taken 3 times during winter and spring (October, January, and April). The soil fungi were isolated by soil washing, enumerated and identified. The differences between the two soils were less than the seasonal variation in occurrence of the soil fungi. More fungi were isolated from the two soils in January than in October and April. In January and April, a higher number of fungi was isolated from the ‘organic’ soil than from the ‘conventional’ soil, indicating a higher potential for decomposing organic material. The species richness was also higher in the ‘organic’ soil,Penicillium janczewskiibeing the most frequent species. All tested isolates ofP. janczewskiiproduced griseofulvin.

ISSN:0144-8765    

DOI:10.1080/01448765.1989.9754520

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Toothpick ammi (Ammi visnaga(L.) Lamarck, Apiaceae), a summer annual of Eurasian origin, commonly occurs along agricultural field margins in the Sacramento Valley of northern California, typically flowering from June to August. Observations during 1979–1984 yielded 65 distinguishable insect taxa attending the flowers, including 60 groups that were at least in part entomophagous. Peak attendances occurred for Braconidae, Ichneumonidae, Sarcophagidae, Sphecidae, Tachinidae, and Vespidae during early morning hours.

ISSN:0144-8765    

DOI:10.1080/01448765.1989.9754521

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

ISSN:0144-8765    

DOI:10.1080/01448765.1989.9754522

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

ISSN:0144-8765    

DOI:10.1080/01448765.1989.9754523

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

ISSN:0144-8765    

DOI:10.1080/01448765.1989.9754524

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

ISSN:0144-8765    

DOI:10.1080/01448765.1989.9754525

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

ISSN:0144-8765    

DOI:10.1080/01448765.1989.9754517

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor