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The influence of frequency of cutting on the yield, chemical composition, digestibility and nutritive value of some grass species Texte intégral
1938
Five species of indigenous grasses, namely Cloris gayana, Setaria Lindenbergiana, Cencrus Ciliaris, Digitaria Pentzii Pretoria small, and Panicum Maximum, were established each in five replications on 25 plots, each measuring (24 x 17) square feet, in a Latin Square arrangement. Each plot was again subdivided into five equal portions and a different treatment allocated at random to each subplot within a main plot. The effective cutting area of a subplot measured (22 x 3) square feet. The experiment covered two growing seasons and various treatments were applied. The objects of the investigation were to study the effect of the treatments on the yield, chemical composition, digestibility and the nutritive value of the grasses under natural conditions of soil and climate. To test the digestibility the produce obtained under any one cutting treatment for all the species was combined as a single sample. Three adult Merino wethers were employed and the hay samples were tested in nine successive periods. Since the results obtained with the grass species studied on the particular type of soil and under the climatic conditions obtaining during the two seasons of the investigation may not be taken to apply generally, it is not possible to lay down clear directions for the practical man. Nevertheless from a consideration of the evidence of the data obtained in this experiment as a whole it seems to be a warrantable conclusion that a system of cutting grasses at approximately 2-monthly intervals during the growing season for the purpose of providing feed during times of scarcity will result in the most economical utilisation of indigenous grass species under natural conditions.
Afficher plus [+] Moins [-]Capillary conductivity of peat soils at different capillary tensions
1938
Wilson, B.D. | Richards, S.J.
Studies were made of the capillary conductivity of water in four peat soils for varying capillary tensions. The conductivities of the soils were found to decrease rapidly and continuously with increasing values for capillary tension. To measure conductivities below the values recorded in this report would necessitate a modification of the apparatus employed in the work in order to avoid moisture losses. An increase in the capillary conductivity of peat soil seems to accrue from prolonged cultivation owing to a type of structure resulting from cultural practices. Certain comparisons are made between the capillary conductivity of peat and mineral soils and of the moisture content of the soils at low conductivity measurements. The conductivity of peat soil was found to be extremely low in the presence of relatively large amounts of moisture. More information is needed before the significance of the conductivity values which are reported can be interpreted with respect to the capacity of the soils to supply water to growing plants.
Afficher plus [+] Moins [-]Bunt reaction of some varieties of hard red winter wheat Texte intégral
1938
Rodenhiser, H.A. | Quisenberry, K.S.
Bunt nurseries of hard red winter wheat were grown for 1 to 6 years at 10 experiment stations in the Great Plains states and at Kearneysville, W. Va., St. Paul, Minn., and Logan, Utah. Each nursery contained 50 varieties and strains of winter wheat grown in duplicate rows. The inoculum used was a composite of collections of T. levis and T. tritici obtained from fields selected at random throughout the state in which the test or tests were made. No variety or selection proved to be bunt-free at all stations, but a large number may be classed as resistant. Oro, Martin, and Hussar, and Minturki to a limited extent, contributed factors for resistance, in hybrid lines, to the races of the bunt organism used in these tests except those collected in Montana. The four above-mentioned varieties were susceptible when inoculated individually with certain races present in Montana and other wheat-growing areas. Bunt-resistant reactions determined by experiments in which bulk inoculum is used should be considered as preliminary evidence only, and such tests should be supplemented by others in which the known races of Tilletia are used individually. Only 10 of 50 wheats tested proved to be resistant to the so-called "dwarf" smut race of T. tritici prevalent in the vicinity of Logan, Utah, and in the Gallatin Valley of Montana. Factors for resistance to this race are present in Martin, Hussar, Ioturk, and Relief.
Afficher plus [+] Moins [-]The correlation among various constituents of forage plants
1938
Greaves, J.E.
Seventy-two samples, representing 16 species of forage plants growing on the Trout Creek winter range in Juab County, Utah, were analyzed for calcium, magnesium, phosphorus, sulfur, crude fat, crude protein, and nitrogen-free extract. The correlation existing between pairs of these constituents has been calculated with the following results: A highly significant correlation was found to exist between ash and calcium, ash and magnesium, ash and sulfur, calcium and magnesium, calcium and sulfur, phosphorus and crude protein, phosphorus and crude fat, and sulfur and crude protein. A highly significant negative correlation was found to exist between ash and phosphorus, ash and crude fat, calcium and phosphorus, calcium and nitrogen-free extract, phosphorus and crude fibre, sulfur and crude fibre, crude fibre and crude protein. These results indicate that the organic sulfur varies, and it is necessary to determine the quantity which is inorganic before one can state its nutritive value. Insofar as these plants are concerned, a total phosphorus determination is a good indication of the nutritive value of the plant because phosphorus and sulfur, phosphorus and protein, and phosphorus and crude fat vary directly, whereas the phosphorus and crude fibre and phosphorus and total ash vary inversely. The fact that the phosphorus and calcium vary inversely indicates that from the nutritional standpoint one must balance the calcium in relation to the phosphorus. This unbalanced relationship may be the reason why supplements used in connection with these forage plants give such poor results.
Afficher plus [+] Moins [-]Breeding rye by continuous selection Texte intégral
1938
Sprague, H.B.
Rye is apparently partly cross-pollinated to the extent of approximately 50%, judging by the amount of xenia evident in a colorless kerneled variety of rye growing adjacent to a colored kerneled variety. Less than 10% of the foreign pollen was effective at a distance of 10 feet under comparatively normal conditions. A total of 216 strains were selected from a mass variety containing 10 varieties and strains after two years of natural crossing. Each of the 216 lines was continued from 1928 through 1937 by selection of superior plants in space-planted rows with open-pollination permitted between all lines in the breeding nursery. Parallel tests of yielding ability were made for all lines, using solid rows, with unselected common rye as the check. After five years of selection, 98 were chosen for 1933-34 on the basis of yield performance during the previous two years, and these were combined to form a new variety named Raritan. Raritan proved to be stable in yielding ability in subsequent generation, exceeding common rye by 10% to 12% in grain yield. Further improvement in productivity by continued selection within each of the 216 lines for the four years ending in 1937 is indicated by the yielding ability of the best 95 lines and by that of the entire breeding nursery. The limitations and advantages of this system of breeding are briefly discussed. Gradual concentration of desirable traits, and elimination of non-adaptive characters is provided without danger of losing valuable genes as usually occurs with inbreeding. The system requires relatively little time and skilled aid, but furnishes no information on inheritance of specific factors.
Afficher plus [+] Moins [-]Effect of certain crops and soil treatments on soil aggregation and the distribution of organic carbon in relation to aggregate size
1938
Metzger, W.H. | Hide, J.C.
Studies of the effect of several crops and certain soil treatments on the degree of aggregation of soils in the field and in the greenhouse are presented. The organic carbon contents of various size groups of soil aggregates obtained from a single soil sample were determined. Samples taken from the soil under growing corn and kafir in field and greenhouse showed as good aggregation under the sorghum crop as under corn. When oats succeeded these two crops in the field, however, soil samples removed from the oats stubble revealed a greater degree of dispersion where oats followed sorghum than where corn was the preceding crop. Sweet clover left the soil better aggregated after 1 year's growth than soybeans, while alfalfa and sweet clover gave similar results. Soil fallowed for 2 years in the field was less aggregated than soil fallowed for 1 year. Limed soil supporting sweet clover and red clover in a greenhouse experiment was more highly aggregated than similar soil unlimed but supporting these crops. Unlimed and unleached fallow soil in the greenhouse was as well aggregated as limed fallow soil. It is suggested that perhaps the combined action of lime and a legume crop, or possibly other crops, produces an aggregating force which lime alone may not exert. The grasses failed to produce the aggregation of the soil expected of them, but their failure in this experiment may have been due to the shortness of the growth period. The more aggregated portions of the soil contained significantly more organic carbon than the less aggregated portions. Ultimate particle size in the various size groups of aggregates was quite similar. Hence it is believed these results lend weight to the assignment of an important role to organic matter in the aggregation of the mineral particles of soils.
Afficher plus [+] Moins [-]The assimilation of calcium and phosphorus by the growing bovine Texte intégral
1938
Three series of long period feeding experiments with cattle are recorded, during which balances of Ca and P for the individual animals were determined. The first experiment was designed to test the availability of various types of phosphate supplement, with varying amounts of CaCO3, when fed at a total P intake level well below the requirement of the particular class of animal used and with a constant Ca: P ratio of 2: 1. Disodium phosphate was slightly more available than either dicalcium phosphate or bonemeal, the relative retentions being 100, 97 and 94 per cent. of the P supplement. The retentions of Ca varied from 65 to 100 per cent. In a second experiment rations containing 8. 5 g. P and 16. 4 g. Ca daily were found to be adequate for steers whereas intakes of 5. 8 g. and 12. 0 g., respectively, were insufficient when tested by blood and bone analyses and Ca and P balances. It was considered that the percentage of ash in the fresh bones was an excellent index of calcification and paralleled the breaking strength of the metacarpus for animals of the same age. In the third experiment, both the levels of P and Ca and the Ca: P ratios were varied over wide ranges for the various groups of heifers. A daily intake of 23 g. Ca and 10. 5 g. P, giving average daily retentions of 9. 7 g. Ca and 6. 6 g. P, was found to be adequate for growing heifers on the bases of blood and bone analyses and Ca and P balances. At this level of P, lowering the Ca intake to 4. 1 g. reduced the P balance more than did raising the Ca intake to 45. 0 g. It is suggested that the main factor which determines retention of Ca or P is the level of intake of the element in question, apart from the ratio in which it is associated with the other mineral element in the food.
Afficher plus [+] Moins [-]USDA Beltsville Agricultural Research Center Log Lodge construction photographs Texte intégral
1938
The USDA Beltsville Agricultural Research Center Log Lodge Construction Photographs contain photographs, documents, and news clippings related to the construction of the Beltsville (Maryland) Agricultural Research Center (BARC) Visitor Center, also known as the Log Lodge.
Afficher plus [+] Moins [-]Une légende forestière. - Le Tire et Aire. Texte intégral
1938
Reuss, Eugène | Blais, Roger
International audience | A FOREST MYTH - THE " TIRE ET AIRE " - This work was wrotten by Eugène Reuss (1847-1926) who was lecturer in second for the lectures on the forest management at the Ecole Nationale des Eaux et Forêts from 1880 to 1889.Reuss, Alsatian by origin, was quite master of the german language ; he devoted a part of his works to get the forets management and the forest organisation of the german countries known. Let us quote specially: Study on the forest experimentation in Germany and in Austria in Annales de la Science agronomique, 1884; The Spessart Forest, in Annales de la Science agronomique, 1896; The Forest teaching in Austria and in Bavaria, Annales de la Science agronomique,1885. The Baron of Seckendorf, Revue des Eaux et Forêts, 1887; The Forest Management in Saxony (on the pseudonym of Reaumont in Revue des Eaux et Forêts, 1885; The Qualified Selection System, report on the work by Tichy « Derqualifizierte planterbetrieb, Munich, 1891, », etc. In 1896 Reuss published a work on the International Forest Exhibition of 1884 in Edinburgh. Reuss is died leaving unfinished a voluminous manuscript on the question of the " Tire et Aire " (system of clear — cutting by successive compartments leaving 6 to 8 standards per acre). It is known that this point out currently the chief method of forest management used by the french foresters on the " AncienRégime ". The study of Reuss is built on the knowledge of numerous texts of archives, concerning specially the famous forest of Fontainebleau that he managed from 1897 to 1911 and from 1914 to 1918, and on the conscientious and methodic abstracts of the old forest works, specially of the collections of the regulations of the XVII° century. This manuscript was revised, often curtailed, sometimes completed by Mr. Blais, inspecteur des Eaux et Forêts, à Nancy, who, besides, gave an introduction and a conclusion. This study includes 3 book: Book I. — The author, in a kind of autobiography, indicates how he came to doubt the classic position of the problem of the" Tire et Aire ". He does so a serious criticism of the authors who preceded him and gives the first complete account of the Great Reformations of the forest of Fontainebleau. Book II. — The author scrutinizes the different forms of the expression " Tire et Aire ". It is one of the most important parts of the book. A philological and historical analysis leads him to distinguish the " Tire et Aire " common age or tire et aire wood cutter from the " Tire et Aire location ". In the first case the " Tire et Aire " gives to the wood cutter the obligation for cutting in following and for making ground clean. In the second case, it is equivalent to a rule of location of fellings. This last case assumes also modalities. If you laya stress on the word " Tire ", you are led to the " Tire et Aire contiguity " which is equivalent to the prescription of marking two successive fellings in following, from place to place. If, on the contrary, you lay a tress on the word " Aire ", that is to say,on the idea of empty space, you are led to the " tire et aire intensity " which can be expressed by the rule of removing all together, at the time of the felling, the greater part of the growing stock. The " Tire et Aire intensity " is then alike the clean felling. Book III. — These distinctions been done, Reuss examines the notion of " tire et aire " in general texts and in ones peculiar to some forests. He reviews so very suggestively our old forestbills. Amongst the results of this important study, it is right to point out essentially, that the old method of high forests management does not include the prescription of felling from place to place. The reality was much more compliant, much more shaded, and it is wrongfully that the famous ordonnance of Colbert 1669 was made to mean that it ordered the " Tire et Aire " as a method of forest management. It is a very good exemple of scientific method which is given by the author when he concludes: " The myth sprung from that the expression" "Tire et Aire "was used from immemorial time in various respects; from that the authors have often involved these respects between them and have not attentively read the text where they were; lastly from that the mistake committed by authors of note have been generally speaking, transcribed, with eyes shut, in the worksof their sucessors. "It is right to point out that the professor Huffel in his famous works on the forest history, had already criticized, very earnestly, the silly and as all of a lump, way, in which the old french sylviculture was fancied.The researchs of Eugène Reuss, on this point, undertaken before the ones of Gustave Huffel and drawn out during all hislife bring, on their posthumous form, something new. The french forest history, in order to be known in an adequate manner, will require many general or regional monographies. Eugène Reuss contributed by this work to light some dark recesses of our forest past time. The publication of that important general monography put to the disposal of the seekers a tool of first value.
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