4.4. Soil fertility managementIn organic cropping systems nitrogen is usually limiting produc-tivity [30] and baking quality. Organic farmers’ nitrogen applicationis 33% less (50 kg/ha) than the recommended rate for conventionalspring wheat production (Table 3). Furthermore, as mineralisa-tion of organically bound nitrogen depends on temperature andwater availability, nitrogen availability is not evenly distributedover the season. Nitrogen scarcity during flowering, which maybe a problem in organic systems [31,32], reduces grain proteincontent and baking quality. Conventional farmers improve bakingquality of moderate baking quality varieties by increasing grainprotein content through additional (late) nitrogen applications.Similarly, traders advice organic farmers since 2005 to increasethe amount and improve timing of nitrogen application, i.e. applyorganic amendments with highly soluble nitrogen at tillering andflowering. However, such amendments are scarce and costly withinorganic cropping systems. Farmers who follow the traders´adviceusually apply waste products (e.g. molasses, feather meal) fromconventional agriculture. The importation of products from outsidethe organic system conflicts with organic principles and consumerexpectations. Therefore the Dutch organic certification schemeforesees in a gradual reduction of the use of nitrogen sources fromthe conventional sector and a total ban from 2020 onwards [33]. Thetightening of the rules on nitrogen provenance will further reduceavailability of this nutrient and thus increase the need for varietiesthat produce high baking quality, under an organic - low nitrogeninput - fertility management regime.Breeders select in nurseries that are fertilised with syntheticfertiliser, but the amount of applied nitrogen is moderate com-pared with conventional farmers´practices and more similar to theamount applied by organic farmers. Due to the difference in natureof the fertilizer (synthetic vs. organic) distribution of nitrogenavailability