SR0084280_SSNL - Laserfiche WebLink

Home Browse Search

B. SOIL PHYSICAL CHARACTERISTICS AND ANALYTICAL TEST RESULTS The UC Davis Soil Web indicates the future effluent disposal area soils consist of Honcut sandy loam (#175), with 4%Chuloak,4%Tinnin, 4%Delhi, and 3%Veritas soils. SSS§5.2,NLS§ 1.1, 1.2. The surface and subsurface soil investigation began on July 27, 2021. A mini excavator was used to dig down to nine ft below grade in an irrigation furrow that accepts winery wastewater in addition to clean irrigation water. Soil samples were obtained from the 3 ft, 6 ft and 9 ft depths, and were retrieved for chemical and particle size analysis. As noted on the attached A&L Laboratory Soil Analysis Report in Appendix B, chemical analyses of the soil samples quantify several constituents that influence nitrate loading for this project. The parameters for nitrate loading assessment are the organic matter, clay content, pH, cation exchange capacity(CEC), organic nitrogen, ammonium nitrogen, Total Kjeldahl Nitrogen(TKN), and the nitrate-nitrogen fractions of the soil. The organic matter in the samples are low and very low, which is the norm for San Joaquin Valley soils. The 3 f depth possesses 11%clay content,and decreases substantially in the 6 ft and 9 ft depths. The pH is acidic in the shallow soils,becomes neutral at 6 ft and alkaline at the 9 ft depth. The CEC indicates low calcium and high magnesium concentrations at 3 ft, but becomes more aligned with agronomically based ratios at the deeper depths. The organic nitrogen and the ammonium fractions shows a precipitous decrease in concentrations with depth. Ammonium molecular retention within clay micro-sites is limited due to the low clay content. Likewise in conjunction with the Org-N and NH4 N,there is a 67%decrease from 3 ft to 9 ft in the TKN concentration(179 ppm to 59 ppm). The nitrate-nitrogen concentrations reveal interesting results: At the 3 ft depth, the NO3-N concentration was 26 ppm, but increased almost sevenfold to 172 ppm in a distance of three ft. The concentration then decreased 31%to 118 ppm at the 9 ft depth. This 31%decrease indicates the denitrification potential that will be used in the nitrate loading calculations and can be attributable to a number of soil chemistry and soil physics influences. NLS§3.3, SSS§5.3,5.4. Table 1 below summarizes the analyzed soil physical and chemical characteristics from the retrieved soil samples: TABLE 1 SOIL PROFILE CHARACTERISTICS AND ANALYTICAL TEST RESULTS SAMPLE SOIL TEXTURE pH AND NITRATE- AMMONIUM- ORGANIC- TOTAL I.D. CLASSIFICATION CATION NITROGEN NITROGEN NITROGEN KJELDAHL i DEPTH EXCHANGE NITROGEN L SAND/SILT/CLAY CAPACITY PERCENTAGES 3 FT Sandy Loam 6.1 26 ppm NO,-N" 4.4 ppm N04 N 175 ppm 179 ppm 67% 22% 11% 6.1 meq/1008 6 FT Loamy Sand 7.0 172 ppm NO3- 1.6 ppm N04-N 135 ppm 137 ppm 77% 20% 3% 8.7 meq/1008 N 9 FT I Loamy Sand 7.6 118 ppm NO3- 1.6 ppm N0;N 57 ppm 59 ppm 83% 12% 5% 1 5.7 meq/100g N Page -3- Chesney Consulting