Takaya et al. - 1974 - Rice cultivation and its environmental conditions

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220 Y. TAKAYA, K. KYUMA, and K. KAWAGUCHI Downloaded by [37.24.145.98] at 13:58 25 May 2015 2) Inland Valley near Badajoz This is the only example of rice land situated inland in the Iberian peninsula. The Guadiana river reveals a braided feature at its middle reach when it comes out from high land of Cambrian rocks to a saucershaped inland basin of Tertiary rocks near Badajoz. Several terraces appear along its braided streams. Near stream portions form narrow strips of alluvial plain with the relative height 1 to 3m from the stream bed. The sediments are composed of fresh gravel with a gray silty to clayey topset bed several centimeters thick. Outside this are situated other surfaces having a relative height 3 to 8 m from the stream bed. These have a yellowish-gray sandy top soil and somewhat indurated red colored clayey underlay at a depth of several ten centimeters. 3) Albufera Lagoon The Albufera lagoonal portion is an oval shaped swale sandwiched between beach and dunes on the east and Quaternary terraces and older hills on the west. The silted-up portion of this lagoon forms a main rice land. Shallow valleys penetrating into Quaternary terraces, which appear like the arms of the lagoonal portion, are another rice growing area. The silted-up portion of the lagoon is flat and lowlying. This is in most places lower than 2m above sea level and some places are as low as to be protected by polder banks. Soils are dominantly clay. The penetrating valleys, on the other hand, are gently sloped, rich in coarser materials including gravels and encountered by calcareous bed rocks at relatively shallow depth, though the main portion is still clayey. The silted-up portion of the lagoon is exclusively utilized for rice growing because of its poor drainability. The valley portion, on the other hand, has a mosaic pattern of rice, vegetables, and citrus trees . .J) Ebro Della The Ebro delta has three physiographic units; levee, backswamp and coastal marsh-beach complex (Fig. 7). The levee is an elevated zone along the present and Q Levee U Backswamp ~ Marsh and beach (SJ Tt•l'l'nce and hill 14·17 Sampling sites Fig. 7. Simplified physiographic map of the Ebro delta, Spain; simplified from BAHR ( 8, 9 ),
!~ice Lands in Mediterranean Countries (!) 22r Downloaded by [37.24.145.98] at 13:58 25 May 2015 ahondoned river channels. This is usually 1 to :3m higher than the adjoining hacl
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Takaya et al. - 1974 - Rice cultivation and its environmental conditions

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