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No description available.

The purpose of this study was to analyze the different soils in Denton, Texas. For the purpose of this study, the soils of Denton County are divided into three general groups with respect to origin: 1)those formed in place by the weathering of consolidated rocks, 2) those formed from the weathering of unconsolidated rocks, and 3) alluvial soils. A chemical analysis of representative samples of Bell Clay, Kirvin fine sandy loam, and San Saba clay has been made, and shown to have a strict correlation with their respective geological origins.

Implementation of Sustainable Management Practices at Two California Central Coast Vineyards and Their Effects on Soil Fertility Dawn Michelle Stimson “Sustainable agriculture” has gained increased popularity in recent years. This study was conducted to determine the effects of sustainable management practices on soil fertility at two California Central Coast vineyards. The effects of cover crops (Erosion Control Mix - blando brome [Bromus hordeaceus], hykon rose clover [Trifolium hirtum All.], and zorro annual fescue [Vulpia mourns]), green waste compost (Forest Blend), and reduced tillage on soil fertility were investigated in San Luis Obispo, California on a clay and sandy loam soil. Between the fall 2007 and spring 2008, which had a low precipitation amount (13.3 & 15.6 inches), there was a significant difference (P <0.001 to 0.007) between vineyards in terms of their mean soil nutrient and ratio concentrations. The range of soil values (soil pH, P, K, exchangeable Ca, Mg, and K, OM, Ca/Mg and C/N ratios) was either completely separate or different between Vineyard One and Two. There was almost no significant difference found between treatments and their effects on soil nutrients, exchangeable cations, and ratios. However, there were some noticeable effects on soil nutrients, exchangeable cations and ratios. Soil P and K concentrations increased in most areas (except cover crop/till where it decreased slightly). Soil P increases ranged from 14 to 143% while potassium increases ranged from 9 to 78%. Soil OM increased in all areas at both vineyards (5 to 55%). Ca/Mg ratios increased in some areas between 8 and 43%. C/N ratios increased in all areas between 5 and 85%. Soil type appears to affect soil nutrients, exchangeable cations, and ratios more than sustainable management practices. Keywords: Sustainable, vineyard, and soil nutrients.

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No description available.

No description available.

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A field experiment was conducted to evaluate the possibility of using shallow reservoirs containing aquatic plants to reduce excess nutrient levels of agricultural drainage effluent from organic soils. The reservoir systems consisted of three small reservoirs in series, containing separate stands of Eichhornia crassipes, Egeria densa and Typha sp., and a single large reservoir containing equal areas of all three aquatic plants. A control reservoir without plants was included. Drainage water from organic soils was pumped through each reservoir at 39.6 l/sec., 6 hours per day, 6 days per week. the major nutrients monitored in theses flow-through systems included nitrate-N, ammonium-N, total-N, ortho-P (soluble reactive phosphorus) and total-P. Temperature, pH, alkalinity, dissolved oxygen, carbon dioxide and turbidity were also monitored at the inflow and outflow of each reservoir system. Standing crop measurements and plant tissue analysis for nitrogen and phosphorus were conducted every 21 days. When a single large reservoir was used, effluent nitrate-N, ammonium-N, ortho-P and total-P concentrations decreased by 65%, 57.9%, 70.3% and 51% respectively, while organic-N concentrations increased by 7.2%. In the a series of small reservoirs the concentrations of nutrients decreased by 80%, 73%, 33%, 74%, and 70% for nitrate-N, ammonium-N organic-N, ortho-P and total-P respectively. The dissolved oxygen increased and turbidity was reduced in both reservoir systems. The bicarbonate and carbonate equilibrium in the series of reservoirs and control reservoir shifted to the carbonate sides as carbon dioxide was reduced. The carbon dioxide in the large reservoir remained at the same concentration throughout the study. The standing crop in both reservoir systems was similar with an average of 11.6 mt/ha grown in R-1 and 11.2 mt/ha grown in the series of reservoirs. The nitrogen retained during the study was 1017 kg/ha and 750 kg/ha in the series and the large reservoir respectively. Phosphorus retained in the series was 249 kg/ha while the large reservoir retained 211 kg/ha of phosphorus. The series of reservoirs was more effective in reducing the nutrient levels of the drainage effluent than the large single reservoir. The results obtained from this study indicated that reservoirs in series can be used to reduce excess nutrient levels of agricultural drainage waters. However, further studies are necessary to increase the efficiency of the system and to accelerate plant removal. The physical, chemical, and biological processes involved in removal of the nitrogen and phosphate should be optimized in future applications.