摘要:

Certain herbs, in particular chicory (Cichorum intybus), ribgrass (Plantago lanceolata), salad burnet (Poterium sanguisorba), sheep's parsley (Petroselinum crispum) and yarrow (Achillea millefolium), are regarded by farmers as being mineral-rich and deep-rooting, thereby adding essential variety to animal diet and improving soil structure and composition. This historical review of research into and attitudes towards the inclusion of herbs in leys in Britain covers the period from 1850 to the present.

ISSN:0144-8765    

DOI:10.1080/01448765.1988.9755134

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The influence of several heavy metals and a sewage sludge on soil catalase and dehydrogenase activities were studied. A pronounced inhibition of enzyme activity was observed with Ag and Hg, slight inhibition occurred with Cu but no inhibition was found with Cd, Pb, Zn, Mg Na or K. Dehydrogenase activity was more sensitive to the toxic action of metals than was catalase activity.

ISSN:0144-8765    

DOI:10.1080/01448765.1988.9755135

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

In a study aimed at stemming the declining fertility of farmer small-holdings in our rural communities the effect of cassava peels (CP) mixed in different proportions with cattle dung (D) on the growth of maize (Zea maysL), yam (Dioscorea rotundata) and yam-bean (Sphenostylis stenocarpa) intercrops was evaluated on a 0.28 ha plot of a mostly sandy loam soil. Each of the treatments—100% CP + 0% D, 75% CP + 25% D, 50% CP + 50% D, 25% CP + 75% D and 0% CP + 100% D—was applied at the rates of 0, 25, 50 and 75 Mg ha−1respectively and, after a month's incubation, planted to maize and yam with yam-bean following a month later.

ISSN:0144-8765    

DOI:10.1080/01448765.1988.9755136

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The pattern of change of soil nutrient status under cocoa plantations, aged between one and 55 years, owned and managed by peasant farmers in southwestern Nigeria, was investigated. The mean values of the measured soil properties were significantly lower under cocoa than those under forest. The pattern of change of these properties over time under cocoa, however, demonstrated a small initial rise followed by a decline to about the tenth year. This was followed by an increase in their values reaching a peak about the twenty-fifth year. Consistent decreases in their values then followed. In order to maintain the nutrient status of the soil beyond the twenty- fifth year it would be necessary for farmers either to apply chemical fertilisers, or to use organic manure as a mulch in the practice of cocoa plantation management. It is also possible that appropriate agroforestry systems may be devised to achieve the same objective.

ISSN:0144-8765    

DOI:10.1080/01448765.1988.9755137

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

FemaleTrioxys indicus, an aphidiid parasitoid of the pigeonpea aphidAphis craccivora, responded to aqueous extracts of the host topically sprayed on to host-infested leaves by examining such areas intensely with their antennae. The host-extract application reduced the host search-time, thus increasing the probability of finding more hosts. By increasing the concentration of the host-extract on the host-patch, the frequencies of host contact, prick and oviposition behaviour increased significantly. Similarly, the retention period of the parasitoids with the hosts significantly increased which, when combined with their intensified behaviour, resulted in a higher degree of host parasitisation. The females parasitised 60% more hosts under host-extract exposure (200 aphid/ml) than with the control. Their area of discovery increased expotentially with increasing host-extract concentration. These studies suggest the value of using the host- extract in the mass culture of the parasitoid in the laboratory. The active ingredients functioning as host-seeking stimulants (kairomones) in the host-extract have yet to be investigated.

ISSN:0144-8765    

DOI:10.1080/01448765.1988.9755138

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

ISSN:0144-8765    

DOI:10.1080/01448765.1988.9755139

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

ISSN:0144-8765    

DOI:10.1080/01448765.1988.9755140

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

ISSN:0144-8765    

DOI:10.1080/01448765.1988.9755142

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

ISSN:0144-8765    

DOI:10.1080/01448765.1988.9755133

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor