Optimum concentrations and/or sufficiency ranges of nutrients are useful for a correct diagnosis and improvement of nutrient status of cultivated plants. To develop boundary‐line approach (BLA) standards for Opuntia ficus‐indica L., a database of N, P, K, Ca, and Mg concentrations in 1‐year‐old cladodes and cladodes fresh‐matter yield was used. The BLA optimum concentrations (associated with estimated maximum yield) for O. ficus‐indica were: N = 13.1 g kg–1, P = 3.2 g kg–1, K = 44.4 g kg–1, Ca = 38.1 g kg–1, and Mg = 17.3 g kg–1. The BLA sufficiency ranges at 95% yield were 8.4–20.3 g kg–1 for N, 2.4–4.2 g kg–1 for P, 38.2–50.8 g kg–1 K, 31.8–45.2 g kg–1 for Ca, and 14.3–20.9 g kg–1 for Mg. The BLA standards are comparable to those obtained in a previous study using compositional‐nutrient‐diagnosis (CND) approach.

No abstract

No abstract

The purpose of this study was to compare chlorinated and ozonated water in reducing Salmonella typhimurium inoculated onto fresh ripe tomatoes. Surface-inoculated tomatoes were immersed/sprayed with chlorinated (200 mg l(-1)) and ozonated water (1 and 2 mg l(-1)) under 2 and 100 nefelometric turbidity units (NTU). Contact times were 120 and 30 s for immersing and spraying applications, respectively. Immersing in chlorinated water and low turbidity resulted in the most effective application with 3.61 log(10) bacterial reduction, while 1 and 2 mg l(-1) of ozone reduced 2.32 and 2.53 log(10), respectively. High turbidity and chlorine reduced the bacterial counts by 3.39 log(10), while 1 and 2 mg l(-1) of ozonated water and low turbidity reduced the bacteria by 1.48 and 1.92 log(10), respectively. Spraying chlorinated water reduced bacteria by 3 log(10), and ozonated water at 1 and 2 mg l(-1) reduced counts by 1.84 and 2.40 log(10), respectively. No statistical differences were found between chlorine and ozone (2 mg l(-1)) during spraying applications (p < 0.05). The use of ozonated water both in immersing and spraying applications is suggested when water turbidity remains low.

Virus removal was studied in a multispecies subsurface‐flow constructed wetland. Tracer studies and a virus survival test were conducted using bromide and bacteriophage PRD1 that were simultaneously added into a 6‐year‐old gravel‐filled wetland. The estimated dimensionless variance and the observed bromide breakthrough curve suggest a plug‐flow reactor with some dispersion. Most of the PRD1 was removed during the first 4 days; however, the PRD1 background concentration was not reached by the end of the study. Average bacteriophage removal was 98.8%, whereas bromide mass recovery was 75%. The removal rate of PRD1 was estimated to be −1.17 d−1; in contrast, its inactivation rate in situ for a 12.4‐day period was −0.16 d−1. Apparently, virus removal is governed by an initial irreversible attachment followed by a comparatively long inactivation period. This study suggests that a subsurface‐flow wetland can decrease the virus load by approximately 99% with a 5.5‐day detention time.