The analysis was performed on average field data for 2010 from
four farms of the Province of Siena (Table 1). The utilization of
arable land was 5 ha yr1. The variety of sunflower crop used was
high oleic. Sunflower seeds are produced with intensive use of
mineral fertilizers and pesticides, a common practice in conventional
farming. The sunflower production systems analyzed
differed in the form of mineral nitrogen fertilizers applied after
sowing with both ammonium nitrate (NH4NO3) and urea
(CO(NH2)2). Ammonium nitrate and urea contain nitrogen in
different forms. Plants cannot use the nitrogen content in either
fertilizers until it has been converted to the nitrate form. The use of
ammonium nitrate allows a faster absorption of nitrogen from the
plants than urea (particularly for low temperatures soils). The same
yield for the cultivation systems was assumed. The analysis focused
on the agricultural phase of the sunflower seed production