In the final analysis, sustainable agriculture must derive from applied ecology, especially the principle of the regulation of the abundance and distribution of species (and, secondarily, their activities) in space and time. Interspecific competition in natural ecosystems has its counterparts in agriculture, designed to divert greater amounts of energy, nutrients, and water into crops. Whereas natural ecosystems select for a diversity of species in communities, recent agriculture has minimized diversity in favour of vulnerable monocultures. Such systems show intrinsically less stability (...) and resilience to perturbations. Some kinds of crop rotation resemble ecological succession in that one crop prepares the land for successive crop production. Such rotations enhance soil organic processes such as decomposition and material cycling, build a nutrient capital to sustain later crop growth, and reduce the intensity of pest buildup. Species in natural communities occur at discrete points along the r-K continuum of reproductive maturity. Clearing forested land for agriculture, rotational burning practices, and replacing perennial grassland communities by cereal monocultures moves the agricultural community towards the r extreme. Plant breeders select for varieties which yield at an earlier age and lower plant biomass, effectively moving a variety towards the r type. Features of more natural landscapes, such as hedgerows, may act as physical and biological adjuncts to agricultural production. They should exist as networks in agricultural lands to be most effective. Soil is of major importance in agroecosystems, and maintaining, deliberately, its vitality and resilience to agricultural perturbations is the very basis of sustainable land use. (shrink)

The text of Euripides' Troades depends mainly upon the versions preserved in two manuscripts, viz. Palatinus 287 and Vaticanus 909 . Both these manuscripts are well known and have been several times collated. Their importance in relation to one another and to the other existing manuscripts for the study of the text of Euripides in general has been frequently discussed and is no longer a subject of major controversy. The notes which follow are designed to put on record a number (...) of corrections to the readings ascribed to P and V for the Troades in the apparatus criticus of Prinz-Wecklein and later editors; and to correct and amplify the general descriptions of P and to call attention to certain difficulties in the current views of its relationship to Laurentianus xxxii. (shrink)

Cicero's philosophical works are now exciting renewed interest, in part because he provides vital evidence of the views of the Greek philosophers of the Hellenistic age, and partly because of the light he casts on the intellectual life of first century Rome. This edition uses the 1997 Clarendon text by the acclaimed translator P.G. Walsh.