An evaluation of the Olsen test as a measure of plant-available phosphorus in grassland soils derived from basalt parent material

Abstract. Anecdotal and circumstantial evidence have suggested that the Olsen test underestimates plant-available phosphorus (P) in basaltic soils in Northern Ireland. Therefore, the ability of this test to predict plant-available P in basaltic (and non-basaltic) soils was investigated by regressing Olsen-P data against herbage P indices calculated from plant tissue test data using the diagnosis and recommendation integrated system. The average Olsen-P concentration for a range of fields situated on basaltic soils was considerably lower than the average Olsen-P concentration for a range of fields situated on non-basaltic soils, and yet mean sward P status, as given by the herbage P indices, was similar for both groups of fields. Herbage P indices were also much better correlated with Olsen-P measurements in non-basaltic soils than in basaltic soils. Furthermore, at low Olsen-P values (≶9mgPL⁻¹) some swards on basaltic soils were genuinely deficient in P, while others were sufficient or even in surplus for this nutrient. The results confirm that Olsen-P is inadequate as a predictor of plant-available P in basaltic soils. It is concluded that an alternative soil test is needed to provide a reliable assessment of plant-available P in basaltic soils, to prevent overuse of fertilizer and manure P and to minimize the amounts of P entering local watercourses.     

Spring Barley Responses to Row Spacing and Fungicide Triadimefon in Regions with a Short Crop-growing Season

Aspects of intensive management practices such as high-yielding cultivars, narrow-row spacings and fungicide treatments could potentially increase cereal yields in regions with a short crop-growing season and occasionally dry and hot weather. A field experiment was carried out at McGill University, Canada for three years (1987 to 1989) to test the effects of triadimefon (1-[4-chlorophenoxy]-3,3-dimethyl-1-[1H-1,2,4-triazol-1-yl]-2-butanone, or Bayleton, a trade name) fungicide (0 vs. 140 g a.i. ha⁻¹) and row spacing (10 vs. 20 cm) on the yield components, yield and other agronomic traits (spike emergence, days to maturity, leaf disease and plant height) of spring barley ( Hordeum vulgare L.) cv. Cadette, Laurier and Leger. A cultivar by row spacing interaction resulted in a 11 to 13.5 % increase in grain yield due to narrow rows for Laurier in two out of the three years and up to 16 % for Leger in one year. Over the three years grain yields were on average increased 6 to 12 % due to use of the narrower row spacing. Fungicide application to barley at the early heading stage effectively controlled leaf diseases without influence on yield components or grain yield. Our results indicate that some components of intensive management such as narrow row spacing can be applicable in regions with a short crop-growing season.     

The Effect of Diet on the Biochemical Composition of Juvenile Artemia: Potential Formulations for Rock Lobster Aquaculture

The lipid class and fatty acid (FA) composition of juvenile Artemia fed continuously on four diets—the microalga Tetraselmis suecica , a mix of oat bran-wheat germ-lecithin (OWL), OwL-eicosapentaenoic acid (EPA), and OWL-EPA-arachidonic acid (AA)—were examined over a 9-d experiment in an attempt to approximate the FA profile of phyllosoma larvae of wild southern rock lobster Jasus edwardrii . The main difference in lipid class composition of Artemia fed the four diets was the relative level of polar lipid (PL) and triacylglycerol (TAG). By day 9, the algal-fed Artemia were highest in PL (95% of total lipid) and lowest in TAG (2%), whereas the remaining diets resulted in Artemia with 16–30% PL and 41–82% TAG. After 2 d, the relative FA composition of all Artemia treatments closely reflected those of the diets, with no marked change after further feeding (to day 9). In terms of the content of essential polyunsaturated fatty acids (PUFA), by day 5 Artemia fed: 1) with the algal diet contained 7 mg/g FA dry mass (0.3% DHA, 6.3% EPA, 3.4% AA of total FA); 2) with the OWL diet contained 3 mg/g (0.3% DHA, 0.9% EPA, 0.7% AA); 3) with the OWL-EPA diet contained 55 mg/g (6.2% DHA, 11.6% EPA, 1.1% AA); and 4) with the OWL-EPA-AA contained 83 mg/g (3.8% DHA, 7.5% EPA, 17.4% AA). The PUFA profiles of Artemia using the OWL-oil diets were similar to wild rock lobster phyllmmata, although levels of doco-sahexaenoic acid (DHA) were lower (10% DHA) than in J. edwardsii larvae. On the basis of PUFA composition data alone, the results suggest the suitability of the OWL-oil mixed diets for consideration for feeding to Artemia used in the culture of southern rock lobster larvae, particularly if the level of DHA can be further enhanced.     

S-methylcysteine sulphoxide,the brassica anaemia factor (a valuable dietary factor for man?)

Ruminant animals fed mainly or exclusively on brassica crops may develop a severe Heinz body anaemia. Clinical signs of the disease include haemoglobinuria, jaundice, increase in pulse rate and fall in milk production; there may also be growth retardation. Nitrate and thiocyanates were excluded as primary haemolytic factors in kale which contains up to 2% in DM of S-methylcysteine sulphoxide (SMCO). In test goats, daily intakes of SMCO in the range 15 to 19 g/100 kg liveweight, whether given as kale or the pure synthetic compound, elicited comparable haemolytic responses. SMCO was thus implicated as the major primary toxin in brassica poisoning. Rumen organisms converted SMCO into dimethyl disulphide which mimicked the haemolytic action of kale and SMCO in goats and is thus considered to be the secondary haemolysin. The practical consequence of this disulphide mechanism is that, because there is no simple way of counteracting the systemic action of dimethyl disulphide, prophylactic measures are restricted to limiting the intake of SMCO or to inhibiting disulphide production. Manipulation of rumen flora by dietary means to exclude organisms with SMCO-lyase is seen as a possible way of minimising the problem which in the long term however calls for developing brassica varieties with low SMCO content. The SMCO content of leafy brassicas increases as the plants mature; within a single plant highest SMCO levels are found in young leaves and growing shoots. SMCO is a heritable character and its selection will probably not lead to marked changes in protein or carbohydrate contents. In steers acute haemolytic response with growth inhibition was obtained with daily SMCO intakes, given as cabbage, of 18 to 35 g/100 kg liveweight. At the lower daily intake of 10–15 g the response was sub-acute, but the low grade anaemia produced would probably be incompatible with maximum productivity. Daily intakes below 10 g/100 kg generally lead to mild disturbances only in blood picture; and it is speculated that, on balance, at this level the effects of SMCO may even be beneficial to the animal. The possible prophylactic action of the S-alkylcysteine sulphoxides in coronary heart disease in man is briefly discussed.Resume Les ruminants nourris principalement ou exclusivement de crucifères peuvent contracter une grave anémie à corpuscules endoglobulaires. Les signes cliniques de la maladie comprennent l'hémoglobinurie, la jaunisse, l'élévation du pouls et la baisse de la production de lait et éventuellement aussi un retard de la croissance. Le nitrate et les thiocyanates ont été exclus comme facteurs hémolytiques primaires du chou à feuilles, qui contient jus qu'à 2% en matières sèches du sulfoxyde de s-méthylcystéine (SMCO). Chez les chèvres utilisées comme sujets d'expériences, des doses quotidiennes de SMCO de l'ordre de 15 à 19 g par 100 kg de poids corporel, absorbée sous la forme de chou ou sous celle de composé synthétique pur ont donné des réactions hémolytiques comparables. On a donc conclu que le SMCO était la principale toxine primaire responsable de l'empoisonnement brassicaire. Les organismes du rumen ont transformé le SMCO en disulphide de diméthyle qui a reproduit l'action hémolytique du chou et du SMCO chez les chèvres, et qui est donc considéré comme l'hémolysine secondaire. Étant donné qu'il n'y a pas de moyens simples de contrecarrer l'action systémique du disulphide de diméthyle, les seules mesures prophylactiques sont la limitation de l'absorption de SMCO ou l'inhibition de la production de disulphide. L'action sur la flore du rumen par des moyens diététiques, à fin d'exclure les organismes à SMCO-lyase, semble un moyen possible d'atténuer le problème. Mais à long terme, il faudra développer des variétés de crucifères à faible teneur en SMCO. La teneur en SMCO des crucifères feuillus augmente au fur et à mesure de la maturation. Sur une même plante, les teneurs les plus élevées se rencontrent dans les jeunes feuilles et dans les pousses en croissance. Le SMCO est un caractère héréditaire et une sélection operée en fonction de lui n'entraînera probablement pas de modifications importantes des teneurs en protéines ou en hydrates de carbone. Une réaction hémolytique aiguë avec inhibition de la croissance a été provoquée chez les bouvillons au moyen de doses quotidiennes de SMCO de 18 à 35 g par 100 kg de poids corporel, administrées sous forme de chou. A la dose quotidienne plus faible de 10 à 15 g la réaction a été sub-aiguë mais l'anémie faible qui en résulte serait probablement incompatible avec une productivité optimale. Les doses quotidiennes inférieures à 10 g par 100 kg ne provoquent généralement que de légères perturbations de la formule hématologique. On estime qu'à ce taux les effets du SMCO peuvent même, dans l'ensemble, être bénéfiques à l'animal. L'action prophylactique possible des sulfoxydes de s-alkylcysteine dans les cas de maladies coronaires chez l'homme est examinée brièvement.

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Kurzfassung Bei Wiederkäuern, die hauptsächlich oder ausschliesslich Brassica-Futter erhalten, kann es zu einer schweren Innenkörperanämie kommen. Klinische Anzeichen hierfür sind u.a. Bluthernen, Gelbsucht, erhöhte Pulsfrequenz und Rückgang der Milcherzeugung, ausserdem unter Umständen ein verlangsamtes Wachstum. Nitrat und Thiocyanat wurden als primäre hämolytische Faktoren im Brassica oleracea, das bis zu 2% S-Methylcystein sulfoxid (SMCO) in der Trockenmasse enthält, ausgeschlossen. Bei Test-Ziegen führten Tagesdosen von SMCO im Bereich von 15 bis 19 g/100 kg Lebendgewicht in Form von Brassica oleracea oder dem reinen, synthetisierten Bestandteil zu vergleichbaren hämolytischen Reaktionen. SMCO war also als wichtigstes Primärtoxin bei Brassica-Vergiftungen beteiligt. Die Pansenorganismen setzten SMCO in Dimethyldisulfid um, das die selbe hämolytische Wirkung wie Brassica oleracea und SMCO bei Ziegen hatte und so als sekundäres Hämolysin gilt. Die praktische Folge dieses Disulfidmechanismus ist, dass vorbeugende Massnahmen auf die Begrenzung der SMCO-Aufnahme oder die Verhinderung der Disulfidproduktion beschränkt sind, da es keine einfache Möglichkeit gibt, der systematischen Aktion von Dimethyldisulfid entgegenzuwirken. Eine Manipulation der Pansenflora durch entsprechende Ernährung zur Ausschaltung von Organismen mit SMCO-Lyase gilt als Möglichkeit zur Minimalisierung des Problems, das langfristig gesehen jedoch die Entwicklung von Brassica-Arten mit geringem SMCO-Gehalt erforderlich macht. Der SMCO-Gehalt von Blattkohl nimmt mit zunehmender Reife der Pflanze zu; innerhalb einer Pflanze findet sich der grösste SMCO-Gehalt in jungen Blättern und wachsenden Trieben. SMCO ist ein erbliches Merkmal, und seine Selektion wird vermutlich nicht zu grösseren Aenderungen im Protein-oder Kohlehydratgehalt führen. Bei Ochsen wurde eine akute hämolytische Reaktion mit Wachstumsverzögerung bei täglichem SMCO-Dosen von 18 bis 35 g/100 kg Lebendgewicht in Form von Kohl erzielt. Bei der geringeren Tagesdosis von 10–15 g war die Reaktion subakut, die entwickelte geringfügige Anämie wäre jedoch vermutlich mit maximaler Produktivität unvereinbar. Tagesdosen unter 10 g/100 kg führen im allgemeinen nur im Blutbild zu geringen Störungen; man vermutet, dass alles in allem SMCO bei dieser Dosierung sogar eine positive Auswirkung auf das Tier haben kann. Die mögliche prophylaktische Wirkung der S-Alkylcystein sulfoxide bei Erkrankungen der Herzkranzgefässe beim Menschen wird kurz erörtert.

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Riassunto I ruminanti la cui dieta è in gran parte o esclusivamente rappresentata da cavoli (Brassica spp.) possono essere colpiti da una grave forma di anemia (Heinz body anaemia). I sintomi clinici della malattia comprendono emoglobinuria, ittero, aumento della frequenza cardiaca e caduta della produzione lattea. A volte si può anche avere ritardo della crescita. I nitrati e i tiocianati sono stati esclusi come fattori emolitici primari nei cavoli che contengono fino al 2% in DM di S-metilcisteina sulfossido (SMCO). In experimenti condotti sulle capre, la somministrazione giornaliera di SMCO in dosi di 15–19 g/100 kg di peso vivo, sia sotto forma di vegetale che di prodotto sintetico puro, ha provocato fenomeni emolitici relativamente simili. L'SMCO è stato pertanto indicato come la principale tossina che ha un ruolo primario nell'intossicazione da cavoli. La flora ruminale converte infatti l'SMCO in dimetil bisolfuro, il quale svolge un'azione emolitica simile a quella osservata nelle capre dopo l'assunzione di cavoli e di SMCO; il dimetil bisolfuro, pertanto, e ritenuto costituire l'emolisina secondaria. Le conseguenze pratiche di tale produzione di dimetil bisolfuro è che, non esistendo un metodo semplice per contrastare l'azione sistemica del dimetil bisolfuro, le misure profilattiche non possono essere volte ad altro se non a limitare l'assunzione di SMCO o ad inibire la produzione di bisolfuro. Gli interventi sulla flora del rumine mediante una dieta capace di eliminare i microrganismi provvisti di SMCO-liasi vengono considerati come un possibile mezzo per minimizzare il problema, il quale, tuttavia, se visto a lungo termine, richiede la creazione di varietà di cavoli a basso contenuto di SMCO. Il contenuto di SMCO delle foglie dei cavoli aumenta col maturare della pianta: nella pianta singola i livelli piu alti di SMCO si riscontrano nelle foglie giovani e nei germogli. La presenza di questa sostanza costituisce un carattere ereditario ed un intervento selettivo in tal senso non dovrebbe condurre a significative alterazioni del contenuto in proteine e carboidrati della pianta. Nei vitelloni e stato possibile indurre una risposta emolitica di tipo acuto somministrando giornalmente, sotto forma di cavoli, 18–35 g di SMCO per 100 kg di peso vivo. Un' assunzione giornaliera minore, pari a 10–15 g, ha dato luogo ad una forma emolitica subacuta, ma e tuttavia da ritenere che la lieve anemia cosi indotta non sia compatibile con una produttività ottimale. Livelli giornalieri al di sotto dei 10 g/100 kg hanno causato soltanto lievi alterazioni a carico del quadro ematico, ed è stata avanzata l'ipotesi che, tutto sommato, gli effetti dell'SMCO possano, a questi livelli, essere addirittura di beneficio all'animale. Viene discussa brevemente la possibile azione preventiva degli S-alchilcisteina sulfossidi sulle malattie cardio-coronariche dell'uomo.

     

Effects of organic amendments on evolution of ethylene and other hydrocarbons from soil

Evolution of C₂H₄ from soils under anaerobic conditions was stimulated by amendment with cereal straw, but hay had little effect. Temporary restoration of aerobic conditions resulted in large increases in C₃ and C₄ hydrocarbons, with both straw and hay amendments. Several known products of the fermentative degradation of carbohydrate increased the evolution of hydrocarbons under anaerobic, and to a greater extent, under aerobic conditions. In particular, ethanol and butyric acid promoted the formation of C₂H₄ and propylene, respectively. The association between degradation products and C₂H₄ suggests that both may be implicated when root growth is adversely affected by the anaerobic decomposition of plant residues.