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Benefits and risks of nitrogen fertilizers for support of straw decomposition
Mühlbachová, Gabriela ; Růžek, Pavel ; Kusá, Helena ; Vavera, Radek ; Káš, Martin ; Watzlová, Elizaveta
The methodology evaluates the benefits and risks of generally used nitrogen application to support cereal straw decomposition. The possibilities of reduction of the commonly recommended nitrogen doses were verified. The appropriate fertilization manners are suggested with regard to nutrient availability for following crops including optimal N doses in cases when the N supply is necessary. The recommendations represent the result of field trials in different soil-climatic conditions and also on farms, where different nitrogen fertilizers have been applied to winter wheat straw. The results showed that depending on the weather, the fertilization with nitrogen in the summer and autumn period decomposes 30-50% of the straw in the given year, and without fertilizing then 25-30%. Based on the obtained results, there is recommended to reduce fertilization with nitrogen mineral fertilizers to 4-5 kg N/t of straw If the following crop id the oilseed rape or intercrop with higher nitrogen nutrition demands, there is possible to increase N dose to 6-10 kg N/t straw. This recommendation is related also on liquid manure and organic fertilizers containing nitrogen also in organic form. Lower doses of above mentioned range are recommended if no following crop is sown, higher does if possible to apply before sowing of winter crops or intercrops. Overall straw decomposition was higher after application of fertilizers on straw leaved 3 weeks on soil surface. Straw on soil surface reduces water losses from soil and warming in warm summer period, which improves water, carbon and nutrient retention in a soil.
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