Characterization of Spatial Variability Structure in Three Separate Field Trials on Pesticide Dissipation
✍ Scribed by Vischetti, Costantino; Businelli, Mario; Marini, Mauro; Capri, Ettore; Trevisan, Marco; Del Re, Attilio A. M.; Donnarumma, Lucia; Conte, Elisa; Imbroglini, Giancarlo
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 372 KB
- Volume
- 50
- Category
- Article
- ISSN
- 1526-498X
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✦ Synopsis
Experiments were carried out on three Italian farms to assess the degree of spatial variation of pesticide Ðeld concentration during treatment and during dissipation trials. Test pesticides were chloridazon and metamitron (both sugar-beet herbicides) applied as a tank mix. The classical statistical technique and geostatistics were used to summarize and evaluate variable spatial data.
The results show that the actual values of pesticide concentration for application rate and initial concentration in all three areas are lower than expected, thus indicating that under Ðeld conditions only a part of the pesticide reaches the soil during the distribution. The actual values for both herbicides in all three areas expressed as percentage of expected values ranged from 44É1% to 64É2% for application rate and from 40É5% to 99É5% for initial concentration. The coefficient of variation was similar for both pesticides and ranged from 23É8 to 74É1 for application rate, 24É1 and 58É8 for initial concentration and 11É1 and 110É0 for dissipation half-lives. The high variability in application rate and initial concentration could be ascribed to an uneven herbicide distribution, and in dissipation studies to variation in half-lives for the rate of herbicide loss from soil in di †erent parts of the Ðeld.
Geostatistic analysis indicated little spatial correlation, probably because the sampling sites were widely spaced on the Ðeld. In all cases, the data were not sufficient to estimate the range of inÑuence, probably because of the size of the experimental Ðelds and the sampling strategy.