N fertilizer response of tobacco (Nicotiana tabacum L.) plants as a function of the spring NO3-N content of the soil
1990
Gondola, I. (Dohanykutato Intezet, Debrecen (Hungary))
The effect of 0-120 kg N/ha was studied for three years in the field on a sandy brown forest soil. Due to the dry weather the NO3 + NO2 content in the root zone rose continuously from 6.2 kg to 53.9 kg N/ha. The yield of the previous corp was lower than planned and the plants did not utilize the entire qunatity of N fertilizer, while the NO3 + NO2 was not washed out of the soil to any great extent. The optimum N rate from the economical point of view decreased as the mineral N content of the soil rose. The optimum rate can be determined more acuurately from the mineral N content of the 0-60 cm layer than from the humus content. In the case of sand, if the water management is satisfactory, the NO3 + NO2-N reserves of the 0-60 cm layer can be regarded as equivalent to N fertilizer, so the fertilizer rate must be reduced by the quantity of N present due to the NO3 + NO2 content of the root zone. Over-fertilization can be avcided by means of the mineral N method.
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