Crop productivity under increasing nitrogen rates and different organic fertilization systems in a long-term IOSDV experiment in the Czech Republic†

Abstract

The yields of winter wheat, winter barley, and potatoes in a long-term field experiment on one of the international IOSDV network sites, were evaluated. The experiment was set up in 1983 in Lukavec, Czech Republic, within a potato growing region on a sandy-loam soil. The experiment includes three systems of organic fertilization: Without manure; manure added for the potatoes; and cereal straw ploughed-down, in combination with increasing nitrogen (N) rates from 0–160 kg N ha−1 or 0–200 kg N ha−1, for cereals and potatoes, respectively. The results of two rotations, during the years 2002–2007, were analyzed. Nitrogen rates had a strong effect on the yields of all crops (p < 0.001). The highest average yields of the cereals 7.2–7.4 t ha−1 (wheat), and 5.2–5.5 t ha−1 (barley) were attained with nitrogen rates of 120 or 160 kg ha−1. With potatoes the highest yields of 46–54 t ha−1 were observed with 150 or 200 kg N ha−1. The yield differences between the two highest N levels were small and not significant. Organic fertilizers had a positive impact on the yields of all crops (p < 0.001), with increasing N rates the effect diminished. Manure and straw yield effects for the most part can be attributed to the nitrogen in the manure and the extra N added for better decomposition of the straw. The strong effects of the year conditions upon the yields of all crops (p < 0.001) were moderated by the N level. The coefficient of variability decreased with increasing N levels from 37–22% (wheat), from 33–16% (barley), and from 32–20% (potatoes).