This major land resource area (MLRA) occupies 3,950,395 ha (9,754,062 acres) and is located just inland of the southeastern coast of Texas. Much of this information was obtained from county soil survey reports of this region.
Climate This land area has a humid subtropical climate characterized by warm hot summers. Annual precipitation in MLRA 150A is approximately 950 to 1300 mm with about half falling between April and September, which includes the growing season for most crops. The area is susceptible to hurricanes, which occur every few years. Snowfall is rare. In approximately 90% of the winters no snowfall is recorded. On average, less than 10 mm of snow is recorded. The average relative humidity is about 60% during midday and approaches 90% at dawn. During the summer months, the sun shines 60% of the time possible and 60% of the time during the winter months. Winds prevail from the south-southeast at 15 to 20 km h-1. In the winter months, the average daily high temperature is 13°C with a low temperature of 7°C. In the summer, the average daily temperature is about 28°C with an average daily maximum temperature of 33°C. Average annual temperature is approximately 21°C. The average number of frost-free days is 266 and the average number of growing degree-days ranges from 7000 to 7500.
Geology and Topography MLRA 150A is located in southeastern Texas just inland from the Gulf of Mexico and is known as the Gulf Coast Prairies.
Landuse Agriculture - The main agricultural enterprises in MLRA 150A are growing crops, such as rice, grain sorghum, cotton, and raising beef cattle. Some corn, alfalfa, and vegetable crops are also produced in this area. Farm income is often supplemented by leasing hunting rights for geese, ducks, and deer. Livestock operations are mainly cow-calf. On prairie rangeland and pasture, supplemental feeding is usually needed in winter. Rice has traditionally been produced by tenant farmers that have short-term leases from landowners. Rice is commonly grown on a field for two years. Then the field is fallowed, used as pasture, or used for grain sorghum or soybeans for one year.
Natural Resources - Soil is a very important resource in this region for crop production and pasture. Oil, natural gas, and sand and gravel, are important commercial natural resources. Several underground reservoirs and rivers, streams, and lakes provide fresh water.
Water Resources Water is relatively abundant throughout the region. Precipitation is adequate for crops in most years. In 2 out of 10 years, rainfall from April to September is less than 500 mm. About 50 thunderstorms occur per year, mostly during the summer. Additional water is available from underground sources, lakes, and rivers.
Soils Most of the soils in this area belong to the Gulf Coast Prairies major land resource area. The dominant soils in this area are the Lake Charles, Victoria, Edna, Bernard, Midland, Brazoria, Pledger, Orelia, Telferner, and Dacosta (Table 1). STATSGO soils are presented in Fig. 1.
The Lake Charles Series consists of deep, very slowly permeable, somewhat poorly drained clayey soils on uplands. These soils formed in calcareous clayey sediments. The Victoria series consists of deep, somewhat poorly drained, very slowly permeable soils that formed in clayey marine sediments. These soils are on nearly level to gently sloping marine terraces. The Edna series consists of deep, very slowly permeable, poorly drained loamy soils on uplands. These soils formed in clayey and loamy sediments. The Bernard series consists of nearly level, somewhat poorly drained nonsaline soils. These soils formed in clayey ancient coastal deposits. The Midland series consists of very deep, poorly drained, very slowly permeable soils that formed in clayey sediments of late Pleistocene age. These soils are on terraces and formed under grass vegetation. The Brazoria series consists of nearly level to gently sloping somewhat poorly drained nonsaline soils. These soils formed in recent clayey fluvial deposits. The Pledger series consists of deep, nearly level, somewhat poorly drained nonsaline soils. These soils formed in recent clayey fluvial deposits. The Orelia series consists of deep, somewhat poorly drained, very slowly permeable soils that formed in thick marine sediments on coastal terraces. These soils are on nearly level to gently sloping uplands. The Telferner series consists of deep, very slowly permeable, somewhat poorly drained soils on uplands. These soils formed in clayey and loamy sediments. The Dacosta series consists of deep, very slowly permeable, somewhat poorly drained loamy soils on uplands. These soils formed in calcareous clayey sediments. Various physical properties of these soils are presented in Table 2. Many of these clay soils show a significant temporal change in hydraulic conductivity depending on the water content of the soil, and may have a very high initial infiltration rate depending the moisture status of the soil. Infiltration rates after prolonged dry spells may be 100 to 200 micrometers per second (Lin et al 1997; Lin et al., 1998).
Literature Cited Lin, H.S., K.J. McInnes, L.P. Wilding, and C.T. Hallmark. 1997. Low tension water flow in structured soils. Can. J. Soil Sci. 47:649-654.
Lin, H.S., K.J. McInnes, L.P. Wilding, and C.T. Hallmark. 1998. Macroporosity/moisture effect on infiltration rates in vertisols and vertic intergrades. Soil Sci. 163:2-8.
USDA, 1998. NRCS, National Cartogrophy & Geospatial Center, Fort Worth, Texas.