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Bilance dusíku v půdě ve víceletých polních experimentech
Prchalová, Renáta
The objective of the present study was to evaluate the effect of various forms of fertilisers (mineral, organic, and their combinations) with graded rates of N (N0, N1, N2, N3) on yields of crops (peas, winter wheat, root and tuber crops, spring barley) and the N content in the staple product (HP) and by-product (VP); subsequently to assess the nitrogen balance (uptake and output) in the individual crops in 2009 -- 2012. Experiments involving 9 combinations of fertilisation were established in 1996 at 13 ÚKZÚZ (Central Institute for Supervising and Testing in Agriculture) stations lying in different soil and climate conditions (potato growing region - BVO, sugar-beet growing region - RVO). Yields differed according to region and crop. As a general rule the yields increased with the rates of nitrogen (various rates for the respective crop). Fertiliser application increased potato yields (BVO) much more than yields of sugar-beet (ŘVO). The application of the fertiliser to potatoes increased the yields of subsequently grown spring barley, while after the application of organic fertiliser to sugar-beet the differences in barley yields were minimal. The contents of N in the staple product and by-product usually increased with the N rate; the N contents in grain and straw of both cereals were higher in the ŘVO than in BVO. The total and/or average annual N balance (uptake, output) in both regions was negative in 8 out of the 9 treatments (-- 2 to -- 62 kg N/ha and -- 6 to -- 86 kg N/ha in BVO and ŘVO, respectively). There is no doubt that the application of the fertiliser considerably improved the N balance, but a positive balance was achieved only in combination with the highest N rate in the mineral fertiliser. As the results show, it is necessary to select the adequate rate of N considering the uptake by the yields.
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