The dual experimental constraints of only two years of data collection (1995 and 1996) and relatively few differences among patterns of viticultural practices applied to the three types of treatment plots (i.e., organic, biologically-intensive, conventional) suggest the wisdom of extreme caution in attempting to draw biologically meaningful conclusions from results thus far in the study. However, several patterns of numerical trends indicate directions in which experimental results appear to be progressing. Total soil nitrogen analysis demonstrated differences of only 0.006%between 1995 and 1996, along with a nearly identical tight range of data grouped by treatment for 1996 (0.005%), as well as for 1995 and 1996 combined (0.006%). Data for soil microbiology activity indicates that conventional plots had higher biomass levels than organic or biologically intensive plots. Overall, one should be safe in concluding that no substantially significant differences across treatment plots for the soil chemistry and microbiological parameters as measured in this study were revealed through the 1996 sampling period. Nutritional status of the vines was greatly reduced from the adequate levels expressed during 1995. Nitrogen levels were half of their 1995 levels while magnesium, zinc, and manganese levels showed increases over 1995 levels. There was never any significant differences between nutrient levels in any of the treatments. During 1995 and 1996, arthropod data were collected for the herbivorous western grape leafhopper (Erythroneura elegantula), along with a wide array of natural enemies (i.e., predators and parasitoids), at approximately two-week intervals. With WGLH nymph densities throughout both 1995 and 1996 generally averaging well below 5 per leaf, very little differences between treatments could be reliably detected. The slowly developing grapevine canopy yielded very few beneficial arthropods sampled by leaf counts in 1996. A tremendous number of spiders were collected by pitfall trap sampling in this study during.1996: over one-half million (508,017) spiders were recorded! However, of the half-million spiders trapped in 1996, nearly 95% (3265/3456) belonged to the family Lycosidae, commonly known as wolf spiders and virtually never being found in the grapevine canopy itself. Thus, although these highly abundant lycosid spiders are most certainly generalist predators, the prey upon which they were feeding in 1996 most likely was limited to small soil-dwelling arthropods, which may themselves have had little distinct involvement (good or bad) with the grapevine canopy proper.
/wp-content/uploads/2017/09/AFV-Header-Logo.png 0 0 AVF /wp-content/uploads/2017/09/AFV-Header-Logo.png AVF1996-11-10 14:23:022019-01-22 19:11:01Optimal Viticulture Systems Comparison