No abstract

In order to comply with the European Union regulatory threshold for the adventitious presence of genetically modified organisms (GMOs) in food and feed, it is important to trace GMOs from the field. Appropriate sampling methods are needed to accurately predict the presence of GMOs at the field level. A 2-year field experiment with two maize varieties differing in kernel colour was conducted in Slovenia. Based on the results of data mining analyses and modelling, it was concluded that spatial relations between the donor and receptor field were the most important factors influencing the distribution of outcrossing rate (OCR) in the field. The approach for estimation fitting function parameters in the receptor (non-GM) field at two distances from the donor (GM) field (10 and 25 m) for estimation of the OCR (GMO content) in the whole receptor field was developed. Different sampling schemes were tested; a systematic random scheme in rows was proposed to be applied for sampling at the two distances for the estimation of fitting function parameters for determination of OCR. The sampling approach had already been validated with some other OCR data and was practically applied in the 2009 harvest in Poland. The developed approach can be used for determination of the GMO presence at the field level and for making appropriate labelling decisions. The importance of this approach lies in its possibility to also address other threshold levels beside the currently prescribed labelling threshold of 0.9% for food and feed.

The impact of organic fertilization and the level of mineral nitrogen fertilization on organic nitrogen and humus balance was studied in a long-term field experiment IOSDV Jable in central Slovenia (sub-Alpine climate, average annual precipitations 1345 mm, average annual temperature 9.58C, heavy hydromorphic silty loam, umbric Planosols). During the period 1993-2010, precipitation increased significantly at an average rate of 19 mm a 71 ; over the same period, average annual temperature increased by 0.0258C (l.f.). The increase in annual precipitation had a negative impact on the yield of all crops (maize, wheat and oats). Increases in mineral N rate led to increased yields. At the highest mineral nitrogen rate, farmyard manure (FYM) did not have a positive impact on yield in the investigated crops, although there was a positive effect of straw incorporation on the yield of maize and oats, and a negative impact on the yield of winter wheat. The organic carbon (Corg) level in the soil increased for all treatments, including FYM or straw and mineral N fertilization. The N content in the soil decreased in the treatment with no organic fertilization and no mineral N, and in the treatment with straw and no mineral N. Corg was increased in treatments with organic fertilization and the highest N rates and remained the same in treatments with moderate N fertilization. All C balances were negative.

No abstract

No abstract