Behavior of NO3-N and Accompanying Cations Derived from Urea under Upland Condition -I. Leaching of NO3-N and Accompanying Cations

요소유래(尿素由來) NO3-N 및 동반(同伴) 양(陽)이온의 토양(土壤) 중 행동(行動) -I. NO3-N 동반(同伴) 양(陽)이온의 용탈(溶脫)

  • 윤순강 (농업기술연구소 농화학과) ;
  • 류순호 (서울대학교 농업생명과학대학)
  • Published : 1994.03.31


Lysimeter experiments were conducted to elucidate the behavior of $NO_3-N$ derived from urea applied at different rates and accompanying cations in soils and to further provide fundamental information of rational nitrogen-fertilizer management. Urea was applied at rates of 0, 7, 14, 21, 28 and 35kg N/10a to sandy loam pakced into PVC cylindrical lysimeter(vol. : $0.187m^2$, area $0.43m^2$). Leachates from the lysimeter with or without grass grown were collected periodically and analyzed for $NO_3$ and cations. Grass growth and yield responses to N fertilization were also examined. Dry matter yield and nitrogen uptake increased with the urea application rate. The amount of leachate from the lysimeter was negatively correlated with urea application ratesl($r=-0.95^{**}$). The nitrate leaching loss with grass grown was 230 g N/10a at the maximum rate of 35kg N/10a, but the highest leaching loss was observed as 1,607 g N/10a from the bare plot. Increase in urea application rates decreased significantly leaching losses of Ca, Mg, K and Na(>0.01). The highest leaching loss from the bare plot was observed for Ca but only 6.5% of exchangeable form and 14.0% for K from the grass plot respectively. Equivalent ratio of cations to nitrate leached were 3.2 % for the bare plot and the ratio for the grass plot increased with the urea application rate, ranging from 18.6 to 32.7%.