ORGANIC vs COVENTIONAL

Organic vs conventional chemical composition of an onion

According to Gundersen, Bechmann, Behrens, et al. (2000)

They explain in the abstract that there are statisticaly significant differences but in the table there are only two chemical elements with differences:

I've calculated the student T test using the previous data in the website Graphpad Students T test online.

Also in some examples we have seen that the (std. dev.) is higher than the (mean), and that gives you 0 or a negative number, and I think that is impossible, because we can't have a negative component.

I've also done a search with some minor components like in B and the authors say that there are statisticaly significant differences in organic conditions it's 888 ± 324 mg/kg and in conventional conditions 1590 ± 806 mg/kg and the authors said that de P value with t test is 0.0056 and I've calculated it again and my P value equals 0.0189, there is a difference but not as high as they said.

Gundersen V, Bechmann I.E, Behrens A, et al. (2000) Comparative Investigation of Concentrations of Major and Trace Elements in Organic and Conventional Danish Agricultural Crops. Onions (Allium cepa Hysam) and Peas (Pisum sativum Ping Pong) J. Agric. Food Chem. 2000, 48, 6094−6102