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 71 or 0-200 kg N ha 71 , 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 5 0.001). The highest average yields of the cereals 7.2-7.4 t ha 71 (wheat), and 5.2-5.5 t ha 71 (barley) were attained with nitrogen rates of 120 or 160 kg ha 71 . With potatoes the highest yields of 46-54 t ha 71 were observed with 150 or 200 kg N ha 71 . 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 5 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 5 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).

Simulation of nitrogen leaching and nitrate concentration in a long-term field experiment

“…The simulated average N leaching and nitrate concentrations were in a tight (R2= 0.98, n=15) non-linear association with the increasing total N inputs in the fertilizers, manure, and straw ( Figure 2). Correspondingly, the relationship between the total N inputs and the yields was similar in all three treatments (Káš et al 2010). The regression of total N inputs on the average nitrate concentration suggested further that the level of 50 mg*l -1 was reached with N input 148 kg N*ha -1 y -1 , corresponding to an average simulated N leaching 22 kg N*ha -1 y -1 (Figure 2).…”

“…However, Köhler et al (2006) showed that even a strong decrease of N fertilization (severely reducing yields) did not substantially lower nitrate leaching within a period of five seasons, due to the mineralization of soil organic matter. The rapid increase of leaching and nitrate concentration above a certain level of nitrogen input, described by many authors, corresponds to diminishing increases of the yields at high N inputs (Figure 3) (Káš et al 2010).…”

“…The long-term field experiment has been carried out from 1983 to the present in Lukavec, Czech Republic, as a member of the network of Internationale Organische Stickstoff Dauerdüngungs Versuche (IOSDV) international experiments (Káš et al 2010). The experimental site (49 o 33´ N, 14 o 58´ E) is 620 m a.s.l., the soil is sandyloam Eutric Cambisol, and the average temperature and precipitation are 6.9 o C and 686 mm.…”

“…Manure contributed on average 150 kg N*ha -1 , straw 19 -25 kg N*ha -1 . For more detail on the experiment see Káš et al (2010).…”

Soil phosphorus and potassium availability in long-term field experiments with organic and mineral fertilization

“…The yields of winter wheat increase depending on the applied mineral nitrogen (N) dose particularly in areas with unfavourable soil-climatic conditions (Káš et al 2010). Bischoff (1995) showed that combined mineral and organic fertilization increased crop yields more than mineral treatments only.…”