THE USE OF HERBICIDES IN ALTERNATE HUSBANDRY AS A SUBSTITUTE FOR PLOUGHING

Summary. It is practicable to use herbicides as an alternative to ploughing grass swards for the preparation of a seedbed for the sowing of cereals and kale. The yields of spring barley and kale following a glaass/clover sward killed with 10 lb/ac amitrole-T were similar to those obtained following ploughing. Yields of tip to 40 cwt/ac of winter wheat were obtained following grass swards killed with amitrole-T compared with up to 45 cwt/ac after ploughing.
The ideal herbicide must kill all plants in a sward and have no residual toxicity to the subsequent crop. At 10 lb/ac, amitrole-T killed most plants in the sword, but it was considered necessary to delay sowing for at least 3 weeks after spraying to minimize the danger of residual toxicity. Ploughing gave the lowest incidence of grasses persisting from the sward. Paraquat did not control clover and Agropyron repens , while broad-leaved weeds were more common on the ploughed than on the sprayed land.
There were differences in the amount of nitrogen mineralized in ploughed and In undisturbed soil, but these were insufficient to affect crop yields materially. When a lower yield followed herbicidal destruction of the sward, this was not accompanied by a reduced percentage nitrogen content.
L'emploi des déherbants pour la rénovation des prairies     

Giant radiation-induced color halos in quartz: solution to a riddle

The radii of radiation-induced color halos(RICHs) surrounding radioactive mineral inclusions in mica generally correspond closely to the calculated range of common uranogenic and thorogenic alpha particles in mica. Many exceptions are known, however, and these variants have led investigators to some rather exotic interpretations. Three RICHs found in quartz are identified as aluminum hole-trapping centers. Whereas the inner radii of these RICHs closely match the predicted range of the most energetic common alphas(39 micrometers), the color centers observed extend to 100 micrometers. Migration of valence-band holes down a radiation-induced charge potential might account for enigmatic RICHs. Such RICHs provide natural experiments in ultraslow charge diffusion.     

The impact of the Department of Phytopathology at the Wageningen Agricultural University, as evaluated by citation analysis

The results of a citation analysis of all publications by the Department of Phytopathology which appeared in the period 1969–1987, but based on citations recorded by the Science Citation Index only, are presented. Together with the results of an analysis of self-citations by the eight most cited authors they suggest, that phytopathology as a science is poorly covered by the Science Citation Index.Een citatie-analyse van alle in de periode 1969–1987 verschenen publikaties van de Vakgroep Fytopathologie omvatte uitsluitend citaties voorzover vermeld in de Science Citation Index (SCI).Enkele vermeldenswaardige resultaten betreffen de krommen, die de cumulatieve citatie-aantallen weergeven (Figuren 1b en 2b) en de grafiek, die de relatieve bijdrage van uiteenlopende publikaties aan het totaal der citaties uitbeeldt (Fig. 3). Uit Fig. 2b blijkt, dat het citatieverloop van een gemiddelde publikatie het karakter van een logistische groeikromme vertoont: na een lagfase en een fase van exponentiële groei vlakt de kromme at naar een stationaire fase. Uit Fig. 3 kan worden afgeleid, dat weinig artikelen veel, en vele weinig tot het totale aantal citaties bijdragen; zo nemen 25 van de in totaal 321 geciteerde artikelen 50% van het totale aantal (3659) citaties voor hun rekening!