Effects of soil disturbance on weed seedling emergence and its long-term decline

The long-term effect of different depths of soil cultivation on weed seedling emergence from naturally occurring populations of weed seeds in the soil was examined in four experiments on land previously in pasture, raspberry canes or intensive vegetable production. At approximately monthly intervals, weed seedlings were counted and then killed with contact herbicides, after which plots were cultivated to 250 or 10mm, or were left undisturbed. The treatments were continued for 7 years. One experiment was then discontinued whilst the previously uncultivated plots on the other three were cultivated to 150 mm at approximately monthly intervals for a further 4 years in one experiment, and for 8 years in the other two. After the first year, very few seedlings emerged in the uncultivated and shallow cultivated plots, and seedling numbers declined slowly in the deep-cultivated plots. Under repeated deep cultivation, seedling emergence of almost all species declined exponentially. Different species declined at different rates, with Rubus idaeus L., Plantago lanceolata L., Veronica arvensis L. and Ranunculus spp. being the most rapidly declining group. Rates of decline for individual species were similar to those observed in Europe.Juncus bufonius L. behaved differently from the other species, and showed no decline in seedling numbers. In the initial 7-year period, 28 000 weed seedlings per m^?2 emerged from the deep-cultivated plots on soil previously cropped with vegetables. Over the same period, less than 11 000 seedlings emerged in shallow-cultivated plots, and just over 4000 in uncultivated plots. In the second phase of the experiments, fewer seedlings of most species emerged than in the first phase, and the decline in numbers of Coronpous didymus (L.) Sm. seedlings was slower. Résumé Les effets à long terme de différentes profondeurs de travail du sol sur la levée des mauvaises herbes ont étéétudiés sur des populations naturelles dans des parcelles dont les précédents étaient: paturage, framboisier ou maraichage intensif. À des intervalles d'environ un mois, les jeunes plantes de mauvaises herbes étaient dénombrées puis détruites à l'aide d'herbicides de contact, aprés quoi les parcelles étaient travaillées sur 250 ou 10 mm, ou laissées sans intervention. Cette premiére phase a duré 7 ans. Une expérience a alors été arretée et les parcelles précédemment non cultivées des trois autres ont été travaillées à une profondeur 150 mm, à des intervalles d'environ un mois pendant 4 ans dans un expérience, et pendant 8 ans dans les deux autres. Aprés un an, trés peu de mauvaises herbes levaient dans les parcelles non cultivés et dans celles travaillées superficiellement, et le nombre de levées diminuait lentement dans les parcelles travaillées profondément. Lá oú le travail profond était répété, les levées de presque toutes les especes declinaient exponentiellement. Les différentes espéces déclinaient à des vitesses différentes,Rubus idaeus L., Plantago lanceolata L., Veronica arvensis L. et Ranunculus spp. déclinant le plus rapidement. Les vitesses de diminution pour les differentes espéces étaient similaires à celles observées en Europe. Juncus bufonius L. se comportait différemment des autres espéces et ne montrait aucune décroissance du nombre de levées. Au cours de la période initiale de 7 ans, 28 000 mauvaises herbes par m^?2 levaient dans les parcelles maraicherés travaillées profondément. Au cours de la meme periode, moins de 11000 mauvaises herbes lavaient dans les parcelles travaillées superficiellement et un peu plus de 4000 dans les parcelles non travaillées. Dans la seconde phase de I'expérience, on observait moins de levées de la plupart des especes que au cours de la premiére et la decroissance du nombre de levés de Coronpous didymus (L.) Sm. était moins rapide. Einfluβ der Bodenbearbeitung auf Keimung und Populationsdynamik von Unkrautern Der langfristige Einfluβ verschieden tiefer Bodenbearbeitung auf die Keimung von Unkrautern aus der naturlich gegebenen Samenbank im Boden wurde in 4 Versuchen auf Flachen untersucht, die vorher als Weide oder mit Himbeer oder intensiven Gemusekulturen genutzt worden waren. Die Keimpflanzen wurden 7 Jahre lang etwa monatlich ausgezahlt und mit Kontaktherbiziden abgetotet, danach wurden die Parzellen 25 tief 15 cm, tief oder gar nicht bearbeitet. Ein Versuch wurde beendet, wahrend eine der 3 ubrigen unbearbeiteten Parzellen fur weitere 4 Jahre und die anderen beiden fur weitere 8 Jahre in etwa monatlichen Abstanden 15 cm tief bearbeitet wurden. Am Ende des ersten Jahres liefen auf den unbearbeiteten und den flach bearbeiteten Flachen sehr wenige Keimpflanzen auf; auf den tief bearbeiteten Flachen nahm die Zahl der Keimpflanzen langsam ab. Bei wiederholt tiefer Bodenbearbeitung verringerte sich die Zahl der Keimpflanzen fast aller Arten exponentiell. Am schnellsten sank die Keimrate bei Rubus idaeus L., Plantago lanceolata L., Veronica arvensis L. und Ranunculus spp. Die Abnahme der Keimrate war bei den einzelnen Arten ahnlich wie in Europa beobachtet. Juncus bufonius L. verhielt sich von den anderen Arten abweichend und lieβ keine Abnahme der Keimrate erkennen. In der anfanglichen 7-Jahres-Periode keimten auf den vorher gemusebaulich genutzten, tief bearbeiteten Flachen 28000, den flach bearbeiteten weniger als 11 000 und den unbearbeiten gut 4000 Samen m^?2. In der 2. Versuchsphase wurden bei denmeisten Arten weniger Keimpflanzen als in der 1. beobachtet, und die Abnahme der Keimrate von Coronopus didymus (L). Sm. war langsamer.     

Vitamin D doses for alpacas (Lama pacos)

OBJECTIVE: To assess the effectiveness of cholecalciferol (D3) doses for maintaining adequate vitamin D status in crias and adult female alpacas at pasture. DESIGN: A field experiment during winter and early spring in a herd on a farm in South Australia. ANIMALS AND PROCEDURE: Crias, usually less than 6 months of age and female alpacas, aged 2 to 6 years, were given a single subcutaneous dose of 0, 1000 or 2000 IU D3/kg body weight. Plasma concentrations of 25-hydroxycholecalciferol (25-OH D3), phosphorus, calcium and vitamins A and E and alkaline phosphatase activity were measured at intervals over a period of 16 weeks after treatment. RESULTS: Crias not given a vitamin D supplement had reduced growth rate during winter and one animal showed clinical signs of rickets. Vitamin D treatment had no effect on the body weight of mature females. Vitamin D supplements increased the 25-OH D3 and phosphorus concentrations in plasma of both crias and adult females; alkaline phosphatase activity was not affected by treatment. CONCLUSION: It is suggested that for alpacas in southern Australia a subcutaneous dose of 1000 IU D3/kg body weight to crias in late autumn and again in mid winter and to adult females in mid winter should prevent vitamin D inadequacy.     

识别假劣、失效兽药的简易方法

介绍了识别假劣、失效兽药的简易方法,包括假劣兽药的外观识别和部分失效兽药的识别,可供畜牧养殖者参考.     

Evidence for Widespread 26Al in the Solar Nebula and Constraints for Nebula Time Scales

A search was made for 26Mg (26Mg*) from the decay of 26Al (half-life = 0.73 million years) in Al-rich objects from unequilibrated ordinary chondrites. Two Ca-Al-rich inclusions (CAIs) and two Al-rich chondrules (not CAIs) were found that contained 26Al when they formed. Internal isochrons for the CAIs yielded an initial 26Al/27Al ratio [(26Al/27Al)0] of 5 x 10(-5), indistinguishable from most CAIs in carbonaceous chondrites. This result shows that CAIs with this level of 26Al are present throughout the classes of chondrites and strengthens the notion that 26Al was widespread in the early solar system. The two Al-rich chondrules have lower 26Mg*, corresponding to a (26Al/27Al)0 ratio of approximately 9 x 10(-6). Five other Al-rich chondrules contain no resolvable 26Mg*. If chondrules and CAIs formed from an isotopically homogeneous reservoir, then the chondrules with 26Al must have formed or been last altered approximately2 million years after CAIs formed; the 26Mg*-free chondrules formed >1 to 3 million years later still. Because 26Mg*-containing and 26Mg*-free chondrules are both found in Chainpur, which was not heated to more than approximately400°C, it follows that parent body metamorphism cannot explain the absence of 26Mg* in some of these chondrules. Rather, its absence indicates that the lifetime of the solar nebula over which CAIs and chondrules formed extended over approximately5 million years.     

Tail docking in dogs: A sample of attitudes of veterinarians and dog breeders in Queensland

One hundred veterinarians and 100 breeders of traditionally docked dogs from Queensland were surveyed by telephone to determine their attitudes towards tail docking. Eighty-four percent of the breeders surveyed were in favour of docking, whereas 83% of veterinarians were opposed to the practice. Most pups were docked between 1 and 3 days of age. All veterinarians surgically amputated the tail, whereas 16% of breeders applied rubber bands to the tail. Seventy-six percent of the veterinarians, but only 18% of the breeders believed that docking caused significant to severe pain. No veterinarians, but 25% of the dog breeders believed that docking was painless. Although recent changes to the Queensland Canine Control Council's rulings allow dogs with intact tails to be shown in traditionally docked classes, the requirement of breed standard was cited as the major reason for tail docking by both breeders and veterinarians.