Article Figures & Data
Figures
- FIG. 1.
Experimental design. SCL and LS soils were fertilized with inoculated or uninoculated manure and stored under 1 March to 9 August or 1 June to 28 September conditions. Each rectangle indicates a soil bed; two contiguous rectangles denote two half-beds. Vegetables were planted as indicated.
- FIG. 2.
Average daily high and low temperatures for 1 March to 1 October simulated in the environmental chambers, based on Madison, Wis., averages for 1985 to 1994.
- FIG. 3.
Total watering amounts for soil beds compared with average monthly precipitation for Madison, Wis., based on 1970 to 1999 data.
- FIG. 4.
Amount and frequency of watering during March to October conditions simulated in controlled-environment chambers. Each bar indicates a watering.
- FIG. 5.
Survival of S. enterica serovar Typhimurium (⧫) and E. coli (▦) in manure-fertilized LS (A) and SCL (B) after a 1 March manure application. Each point represents mean of three samples; error bars indicate ± 1 standard deviation. When cells were not detected by direct plating, a value of 1.0 log CFU/g was assigned for calculation of the mean and standard deviation. Sampling times for which samples were enriched before plating (after 9 weeks) are not shown.
- FIG. 6.
Survival of S. enterica serovar Typhimurium (⧫) and E. coli (▦) in manure-fertilized LS (A) and SCL (B) after the 1 June manure application. Each point represents the mean of three samples; error bars indicate ± 1 standard deviation. When cells were not detected by direct plating, a value of 1.0 log CFU/g was assigned for calculation of the mean and standard deviation.
- FIG. 7.
Log CFU of S. enterica serovar Typhimurium and E. coli/gram in SCL (A) and LS (B) soil containing inoculated (+) and uninoculated (−) manure after a simulated 1 June application. Each point represents the mean of three samples; the standard deviations for S. enterica serovar Typhimurium and E. coli in inoculated manure are the same as in Fig. 6. The standard deviations for E. coli in uninoculated manure ranged from 0.09 to 1.17 log CFU/g. A value of 1.0 log CFU/g represents no S. enterica serovar Typhimurium or E. coli detected by direct plating (no enrichment).
Tables
- TABLE 1.
Chemical and textural characteristics of SCL and LS soils
Soil type pH % Texture category Total N (%) Available Sand Silt Clay P (ppm) K (ppm) SCL 6.6 24 62 14 0.271 70 29 LS 5.8 98 1 1 0.0279 67 64 - TABLE 2.
Survival of S. enterica serovar Typhimurium and E. coli in manure-fertilized SCL and LS soils exposed to freezing-thawing treatments
Treatmenta Survivalb S. enterica serovar Typhimuriumc E. coli SCL LS SCL LS Group A −20°C, 4 mo; thaw NT NT + (1) + (1) 1 freeze-thaw cycled + (1) + (1) + (1) + (1) 10 freeze-thaw cycles + (1) + (1) + (1) + (1) 10 freeze-thaw cycles; 4 mo, −20°C; thaw NT NT + (1) + (1) 10 freeze-thaw cycles; 4 mo, −20°C; 10 freeze-thaw cycles + (2) + (1), − (1) + (2) + (2) Group B −20°C, 4 mo; thaw 3.22 (1) 3.17 (1) 1.87 (1) 3.36 (1) 1 freeze-thaw cycle 4.96 (1) 4.41 (1) NT NT 10 freeze-thaw cycles 1.57 (1) <DLe (1) 3.13 (1) 2.27 (1) 10 freeze-thaw cycles; 4 mo, −20°C; thaw 2.31 (2) 2.55 (2) 2.80 (2) 2.41 (2) 10 freeze-thaw cycles; 4 mo, −20°C; 10 freeze-thaw cycles <DL (2)f <DL (2) <DL (2) <DL (2) ↵ a The history of the soils prior to treatment was as follows. For group A, inoculated manure was applied to soils (in beds), manure-fertilized soils were exposed to 1 June to 28 September conditions, and radish and arugula were grown and harvested. For group B, inoculated manure was applied to soils (in beds), manure-fertilized soils were exposed to 1 June to 28 September conditions, radish and arugula were grown and harvested, and inoculated manure was added to soils in sample bags (initial levels of S. enterica serovar Typhimurium were ca. 5.50 log CFU/g in a soil-manure mixture).
↵ b Survival was determined quantitatively (log CFU/g) or qualitatively (+/−). The number of samples is given in parentheses. NT, not tested.
↵ c S. enterica serovar Typhimurium was not detected without enrichment in each soil type at the time of fall harvest.
↵ d A freeze-thaw cycle consisted of −20°C for 16 h, followed by thawing at 4°C for 8 h.
↵ e <DL, less than the detection limit for LS soil (1.64 log CFU/g).
↵ f <DL, less than the detection limit for SCL soil (1.23 log CFU/g).
- TABLE 3.
Effect of washing on the presence of S. enterica serovar Typhimurium and E. coli on arugula, radishes, and carrots grown in manure-fertilized SCL and LS soilsa
Soil type Vegetable (no. of wk after manure applicationc) Survival of organism (S. enterica serovar Typhimurium, E. coli)b: On unwashed vegetable On washed vegetable In wash water SCL Arugula (16) <DL, <DL <DL, <DL <DL, <DL Arugula (17) +, + +, + <DL, <DL Radish (14) 1.50, NT 1.80, NT 2.79, NT Radish (16) 2.61, 2.65 <DL, 2.53 <DL, 2.78 Radish (17) +, + +, + <DL, 1.92 LS Arugula (16) <DL, <DL <DL, <DL <DL, <DL Arugula (17) +, + −, + <DL, <DL Radish (14) <DL, NT <DL, NT <DL, NT Radish (16) <DL, 1.93 <DL, <DL <DL, <DL Radish (17) +, + −, + <DL, 2.34 ↵ a Manure-fertilized soils were exposed to 1 June to 28 September conditions, with planting on 15 August. Values are from quantitative (log CFU/g) or qualitative (+/−) analysis of a single sample.
↵ b DL, detection limits were 1.39 and 1.60 log CFU/g for radish and arugula, respectively; NT, not tested.
↵ c On 1 June.
