8Johnston A. Nutrients in soil and nutrients for fool pxxxtuction [J]. Better Crops with Plant Foctl,2003 (2) :4 - 5.
9Cordron L M,Camemn K C,Di H J,et al.A comparison of soil and Environmental quality under organic and conventional farming systems in New Zealand[J] .New Zealand J. Agri. Research, 2000, 43(4) :443 - 466.
10The Council for the Rural Area (under the Ministry of Agriculture of Netherlands). Prospects for organic farming[ R]. In: Advice on the opportunities for organic farming in the Netherlands for the period until 2015,2001.13.
