Valley Of Chile Research Articles

Phosphate retention on soils in the central valley of Chile

Abstract The retention of phosphate and the content of available phosphate were estimated by a new method with monobasic sodium phosphate (pH 4.5) and the Olsen's method, respectively, on the Principal soils in the central valley in Chile. Trumaos (Andosols) are, in general, distinctly in the value of P-retention than other soils with the exception of trumaos of alluvial origins. This characteristic of trumaos can be employed for the identification of trumaos among r soils and alluvial trumaos among ordinary ones. The P-retention value of volcanic ash soils of decreases with the crystallization of the amorphous inorganic materials. According to the data of P-retention, certain rojos arcillosos (red clays) are presumed to have surface horizons of volcanic ash origins. Granitic rojos arcillosos are notably low in P-retention compared with other arcillosos. The organic matter content and P-retention value of soils are closely related to each other, suggesting that both organic matter and phosphate are retained by soils on the same a erials though by different mechanisms. The content of available phosphate in surface horizons varied from soil to soil and no difference was noticeable among the soil groups of trumaos, rojos arcillosos, and paddy soils. Also no relation was found between the P-retention value and available phosphate content. However, in lower horizons where plant roots are scarce or absent, no available phosphate was found in trumaos in contrast to the presence of an appreciable amount of phosphate in rojos arcillosos. Phosphate of native trumaos appear to be practically insoluble. The surface soil rich in available phosphate was limited to cultivated fields, suggesting that the available phosphate was largely due to the remnant of applied fertilizers and partly to the remains of organic phosphorus from plants and soil organisms. The content of available phosphate tends to decrease with time after application of phosphates, and a significant negative correlation coefficient was obtained between the amount of available phosphate and the P-retention value of soils at least by three months after application of phosphate. The higher the P-retention value of soils, the less the content of available phosphate, and the faster the fixation of phosphate.

Nitrogen and organic matter of volcanic ash soils of Santa Bárbara Association in Chile

Abstract Santa Barbara association is a group of Andosols widely distributed on the western foothills of the Andes Mountains in the Central Valley of Chile from about 36° to 40° south latitude. The soils of this association may be divided into two groups—south and north—by the characteristics of soil organic matter, although they are much alike in morphology. The line of demarcation between the groups lies at about 38° south latitude. The potential nitrogen fertility or , the content of easily decomposable organic nitrogen is greater in the south soils than in the north soils of which humic matter is at a more advanced stage of humification, as compared with that of the south soils. Dry summers have caused the north soils to lessen in their potential nitrogen fertility and to stimulate humification of organic matter, altering the organic matter in quantity as well as in nature. It is evident that the analysis of soil organic matter is an effectual measure for the characterization of Andosols, and hence fo...

Experimental Studies in Two Genera of Helenieae (Compositae): Blennosperma and Lasthenia

The biosystematics of Blennosperma and Lasthenia (Compositae: Helenieae) are discussed. Blennosperma consists of B. nanum (Hook.) Blake, widespread and racially diverse in California; B. bakeri heiser, a narrow California endemic; and B. chilense Less. of the central valley of Chile. Evidence presented suggests that B. chilense is an amphiploid species derived from ancestors similar to the modern california species. The line giving rise to B. chilense apparently developed during or after the Miocene, migrates to South America, andsubsequently became extinct in North America. Lasthenia (sect. Lasthenia) consists of two closely related species: L. glaberrima DC. of Pacific North America and L. kunthii (Less.) Hook & Arn. of Chile. On several grounds it appears that the Chilean species is a vicariad derived from populations established after long-distance dispersal from the northern hemisphere.

Cordillera of Chile, South America: ABSTRACT

Chile, 2,600 miles long and 100 miles wide, extends from the arid deserts of the North to the cold, windy pampas of the South. It occupies the area from the crest of the Andes to the Pacific Ocean. Geologically, it occupies a long, mobile belt lying west of the stable shield area. Through a series of orogenies it has developed the present Cordilleras. This Andean geosyncline has been a zone of weakness from Precambrian time to the present. The Andean Cordillera, one of the highest mountain chains in the world, is complicated geologically and tectonically. Two principal provinces can be described, the Eastern and Western, separated by the great central valley of Chile, in which lies the capital, Santiago. The Western Cordillera, the older, represents an extensive batholith of continental character, and is largely granitic in character. Normal block faulting and folding occur. The principal uplift occurred in the Upper Mesozoic. The Eastern Cordillera is composed principally of metamorphic and sedimentary rocks, although evidences of its crystalline core are common. Structurally they show block faulting, with some evidence of thrusting toward the east. Principal uplift occurred during the Tertiary and Quaternary. Close inshore in the Pacific are troughs 23,000 feet deep. Recent vulcanism is common. At the southern end of Chile the Andes make a strong eastward swing and thence, by an island arc very similar to the Caribbean Island Arc, join the Andes to the mountains of the Palmer Peninsula of the Antarctic, 600 miles south. End_of_Article - Last_Page 408------------

A geographical interpretation of “El Vergel,” a fundo of the central valley of Chile

A geographical interpretation of “El Vergel,” a <i>fundo</i> of the central valley of Chile