Patent ID: 7670842

Claim:
A method for discriminating an organic crop from a conventional crop, comprising: (a) measuring nitrogen isotope values in a crop sample at appropriate intervals during a single cultivation period; (b) calculating a pattern of nitrogen isotope index according to the formula (I) using the nitrogen isotope values of step (a): δ 15 N=[R sample/ R reference−1]×1,000 (I) wherein δ 15 N is a nitrogen isotope index, R sample and reference are 15 N/( 15 N+ 14 N) ratio of sample and reference, respectively; and (c) determining whether the crop belongs to an organic crop or a conventional crop wherein: (i) if the nitrogen isotope index exhibits an increasing trend during the cultivation period with time, the crop is determined to be a conventional crop during the cultivation period of which a chemical fertilizer had been used as a sole fertilizer in the early growth period; (ii) if the nitrogen isotope index exhibits a decreasing trend after initial increasing trend, the crop is determined to be a conventional crop during the cultivation period of which a chemical fertilizer had been used as a basal fertilizer in the early growth period and as an additional fertilizer in the latter growth period; (iii) if the nitrogen isotope index exhibits almost insignificant fluctuations or a slight decreasing trend during the cultivation period with time, the crop is determined to be an organic crop during the cultivation period of which an organic fertilizer had been used as a sole fertilizer; or (iv) if the nitrogen isotope index exhibits a decreasing trend after initial insignificant fluctuating trend during the cultivation period with time, the crop is determined to be a conventional crop during the cultivation period of which an organic fertilizer had been used as a basal fertilizer in the early growth period and a chemical fertilizer had been used as an additional fertilizer in the latter growth period.