Do cover crops change the lability of phosphorus in a clayey subtropical soil under different phosphate fertilizers?

Plants have developed different mechanisms to absorb and solubilize phosphorus (P) in the soil, especially in environments with low P availability. This study evaluated the effects of different winter cover crops on soil P availability in a clayey subtropical (Hapludox) soil receiving soluble P fertilizer and a rock phosphate applied to the summer crop, under no‐tillage. The experiment was carried out over 3 yrs (2009–2011) with five different cover crop species: common vetch, fodder radish, ryegrass, black oat, white clover and fallow as control. The soil was sampled after the third year of cover crop cultivation and analysed for inorganic and organic P forms according to the well‐established Hedley fractionation procedure. Phosphate fertilizers promoted accumulation of both labile and nonlabile P pools in soil in the near surface layer, especially under rock phosphate. Fertilizer applications were not able to change P fractions in deeper layers, emphasizing that the Brazilian clayey soils are a sink of P from fertilizer and its mobility is almost nil. Although the cover crops recycled a great amount of P in tissue, in a short‐term evaluation (3 yrs) they only changed the content of moderately labile P in soil, indicating that long‐term studies are needed for more conclusive results.     

Incidental phosphorus losses – are they significant and can they be predicted?

Fresh applications of phosphorus (P) may cause ‘incidental’ losses of dissolved and particulate P forms in land runoff when rainfall interacts directly with fertilizers and manures which are spread, or excreted, onto the soil surface. Research indicates that when incidental P losses (IPL) occur, they often make the dominant (50–98 %) contribution to measured P loads in surface and sub‐surface runoff from field plots, with increased risk of eutrophication where P‐enriched runoff is routed directly to the watercourse. Rates of P loss are temporally and spatially very variable (< 1 to 25 % of total P applied) depending on the amount of P applied; the P release properties of the materials applied (% P extractable in water), the timing of storm events after application and the amounts of runoff generated. Large P applications left on the surface of wet, frozen, compacted, and intensively underdrained soils in high rainfall areas are particularly vulnerable to IPL. Concentrations of P in runoff are often greatest during the first storm event following P application, but can remain high for several weeks, or even months after application. Catchment scale impacts are more difficult to quantify due to the effects of dilution with runoff from fields without IPL, and the contributions of P from other sources. Approaches to predicting IPL are discussed and need to be improved in order to assess the contribution of IPL to catchment P loads in river basin management planning. Strategies to control IPL should focus on adoption of more sensitive management practices in fields with a high risk of rapid runoff or preferential flow, and are likely to very effective.     

Rise of the Andes

The surface uplift of mountain belts is generally assumed to reflect progressive shortening and crustal thickening, leading to their gradual rise. Recent studies of the Andes indicate that their elevation remained relatively stable for long periods (tens of millions of years), separated by rapid (1 to 4 million years) changes of 1.5 kilometers or more. Periodic punctuated surface uplift of mountain belts probably reflects the rapid removal of unstable, dense lower lithosphere after long-term thickening of the crust and lithospheric mantle.     

The Response of the Bitch to Treatment with Medroxyprogesterone Acetate

Abstract— —Medroxyprogesterone acetate (M.A.P.) was administered to three groups of bitches as follows:

• 1 Eighty-six bitches received a total of 166 injections of M.A.P. to prevent or suppress oestrus. This procedure was entirely successful in 83 bitches (96.5 per cent) and partially successful or unsuccessful in the remaining 3 bitches. Nine others showed unfortunate sequelae of which three bitches subsequently required an ovaro-hysterectomy, 1 showing a chronic endometritis and 2 showing a gross cystic hyperplasia of the endometrium upon histopathological examination. Methods of reducing the rate of failure are suggested.
• 2 Forty bitches received 5 cm³ M.A.P. (250 mg) to suppress false pregnancy and the results were satisfactory in 31 (86 per cent) of the 36 bitches where a follow-up history was obtained. However, the use of M.A.P. to control this condition is considered to be beyond the financial means of the average client.
• 3 Three “poor risk” cases of pyometra were given 5 cm³ M.A.P. and the initial response was good, but all 3 died subsequently. Two suffered a relapse of pyometra, 1 died of nephritis. This form of therapy demands further investigation.

Two bitches developed signs of diabetes mellitus following the administration of M.A.P. Résumé— —L'Acétate de Medroxyprogesterone (M.A.P.) a ?té administréà 3 groupes de chiennes comme il suit:

• 1 Quatre-vingt six chiennes ont reçu un total de 166 injections de M.A.P., pour prévenir ou supprimer l'oestrus. Ce procédé a eu un réultat parfait dans quatre-vingt trois cas (96.5 pour cent) et un succès partiel or un résultat nul dans les 3 autres cas. Neuf autres chiennes ont montré des séquelles malheureuses et conséquemment 3 chiennes durent subir une ovaro-hystérectomie, une montrant une endomedArite chronique et deux autres, une hyperplasie cystique de l'endomètre, visible à l'oeil nu et vérifiée par examen histologique. Des méthodes pour réduire le nombre d'échecs ont été suggérées.
• 2 Quarante chiennes ont reçu 5 cm³ M.A.P. (250 mgm), pour supprimer une fausse grossesse et les résultats furent satisfaisants dans 31 cas (86 pour cent) de 36 chiennes mises en observation. Cependant, l'utilisation du M.A.P. pour dominer cette situation, est considérée au-delà de possibilités financières d'un client moyen.
• 3 Trois chiennes avec pyométrie, dans un mauvais état général, reçurent 5 cm⁵ de M.A.P., et mêrne que la réaction initiale fut bonne, toutes les 3 décédérent subséquemment. Deux chiennes eurent une rechute de la pyométrie et une décéda à cause d'une néphrite. Cette forme de traitement nécéssite d'autres investigations. Deux cas deéeloppèrent des signes de diabète sucré, suivant l'administration de M.A.P.

Zusammenfassung— —Medroxyprogesteron Acetat (M.A.P.) wurde 3 Gruppen von Huendinnen wie folgt verabreicht:

• 1 86 Huendinnen erhielten im ganzen 166 Injektionen von M.A.P., urn Brunst zu verhindern oder zu unterdruecken. Dieses Verfahren war bie 83 Huendinnen (96.5%) voellig erfolgreich und bie den ucbrigen 3 Huendinnen entweder teilweise erfolgreich oder erfolglos. Neun andere zeigten unerwuenschte Folgen; in 3 Faellen war Ovaro-Hysterektomie erforderlich; davon wurde in einem Fall chronische Endometritis gefunden, und in 2 Faellen stark ausgepraegte zytiscshe Hyperplasie des Endometriums bie histologischer Untersuchung. Methoden zur prozentualen Reduktion der Versager werden vorgeschlagen.
• 1 40 Huendinnen erhielten 5 ml M.A.P. (250 mg), um Pseudo-Schwangerschaft zu unterdruecken. Die Resultate waren bie 31 (86%) von den 36 Huendinnen erfolgreich, wo der weitere Verlauf verfolgt werden konnte. Die Anwendung von M.A.P., um diesen Zustand unter Kontrolle zu halten, is jedoch zu teuer fuer den Durchschnitte-Klienten.
• 1 In 3 Faellen von Pyometrium mit zweifelhafter Prognose wurde 5 ml M.A.P. gegeben. Der Anfangserfolg war gut, aber alle drei starben spaeter. Zwei hatten einen Rueckfall von Pyometrium, ein Tier starb an Nephritis. Diese Behandlungsform bedarf weiterer Untersuchung.

Zwei Faelle entwickelten Symptome von Diabetes mellitus nach der Anwendung von M.A.P.