Impacts of organic and conventional management systems on weeds and insects’ biodiversity

Global farming systems aim to improve productivity while minimizing its negative environmental consequences. Organic farming is one of the solutions for reducing the negative impact of global warming which requires a comprehensive assessment as the extent of its benefits and impacts is largely uncertain in different regions of the world. Thus, this study was done to assess weeds and insects' diversity under organic and conventional farming systems of wheat and potato in a semi-arid region. The experiments were conducted on two certified organic wheat and potato fields and two conventional wheat and potato fields in northeast of Iran during 2011–2013. Insects and weeds sampling were carried out for several times during the growing season. Shannon-Wiener and Simpson's indices calculated for different sampling stages. The results illustrated that species richness and biodiversity indexes of insects in organic wheat fields was higher than the conventional fields. The number of harmful (pest) families in conventional fields was higher than organic fields. The organic potato field had a higher Shannon index for weed communities during the first and second year of the experiment than the conventional one. The reported organic yields were higher than conventional management mainly due to the application of high yielding varieties in organic fields. In summary, our results show that there is a great potential for transformation from conventional to organic farming particularly for wheat production.