Abstract
In order to find out the effect of nitrogen fertilizers on soil pH, EC, $NO_3-N$ and lettuce growth, this study was conducted by pot experiment in plastic film house condition. The square-pot which was $42{\times}54.5{\times}22cm$ in length, width and height, respectively, was filled with two kinds of soils in different soil EC as $0.20dS\;m^{-1}$ and $1.13dS\;m^{-1}$. Seven kinds of nitrogen fertilizers (urea, potassium nitrate, calcium nitrate, ammonium nitrate, ammonium sulphate, complex fertilizer A(11-10-10) and complex fertilizer B(12-12-12)) were treated in same standard rate of nitrogen for lettuce, transplanted the six lettuce seedlings of 10 days grown per pot, and have been grown for 38~44 days with three times harvesting. Soil pH was increased with the potassium and calcium nitrate treatments and decreased with ammonium nitrate, ammonium sulphate, complex fertilzer A and B, and the pH of urea treatments was kept the same value as the pH of before experiment. The growing status of lettuce seedling were surveyed during the early period after transplanting and withering of seedling was occured in all treatments. The withering rates were 10% in soil of EC $0.20dS\;m^{-1}$ and 44% and 42% in complex fertilizer and ammonium sulphate treaments, respectively, in soil of EC $1.13dS\;m^{-1}$. $NO{_3}^-$ contents of lettuce were about $1,000{\sim}2,000mg\;kg^{-1}$ based on fresh weight and these contents were considered to be lower to compare the $NO{_3}^-$ level of EU countries.
질소비종이 토양 pH. EC, $NO{_3}^-$ 함량 및 상추 생육에 미치는 영향을 조사하고자 양분함량이 서로 다른 두 토양을 사각폿트에 충진하여 유리온실 내에서 상추를 재배하였다. 상추재배를 위해, 7종류의 질소 비료(요소, 질산가리, 질산석회, 질산암모늄, 황산암모늄, 복비A(11-10-10), 복비B(12-12-12)를 토양검정 시비량으로 시용하였다. 토양 pH는 질산가리 및 질산칼슘 시용구를 제외한 비료시용구에서 시험전 토양보다 시험후 토양에서 낮아 졌는데, 질소비료중 황산암모늄 시용구에서 가장 낮았다. 토양 EC및 $NO_3-N$은 모든 비료 시용구의 시험후 토양에서 시험전 토양에 비해 높은 경향이었다. 상추의 생존율은 토양 EC가 $0.20dS\;m^{-1}$의 비료 시용구에서는 90% 이상이었으나, 토양 EC가 $1.13dS\;m^{-1}$에서는 감소되었다. 특히, 복비와 황산암모늄 시용구의 생존율은 각각 56%, 58% 정도로 감소되었다. 상추의 생산량은 토양 EC가 $0.20dS\;m^{-1}$에서는 비료 시용구에서 무비료구 보다 높았으나, 토양 EC가 $1.13dS\;m^{-1}$에서는 모든 질소 비료 시용구에서 무비료구 보다 낮았다. 상추 엽내 $NO{_3}^-$ 함량은 모든 비료 시용구에서 약 $1,000{\sim}2,000mg\;kg^{-1}$ FW 정도였다.
(Chngbuk Agricultural Research and Extension Service)
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