ブロッコリー秋作における被覆肥料の施用が土壌からの一酸化二窒素発生に与える影響  [in Japanese] Effects of controlled-release nitrogen fertilizer on soil nitrous oxide emissions from broccoli (<i>Brassica oleracea</i> var. italica) autumn-cultivation field  [in Japanese]

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Abstract

<p>ブロッコリーの秋作において,被覆尿素または被覆硝カルの施用が土壌からのN<sub>2</sub>O発生に与える影響について調べた.2016年9月から11月にかけて,愛媛大学農学部附属農場に無施肥(C)区,尿素(U)区,被覆尿素(CU)区,および被覆硝カル(CN)区をそれぞれ4反復で設けた.CU区とCN区ではU区より全窒素(N)施用量を2割減らし,施用Nの4割を被覆Nで施用した.N<sub>2</sub>Oフラックスを測定し,施用Nから発生したN<sub>2</sub>Oの割合(<i>EF</i>)を算出した.さらに,地温,土壌pH,土壌アンモニウム態Nおよび硝酸態N含量を測定し,作土層からの無機N溶脱量と頂花蕾収量,N吸収量およびN利用率を求めた.被覆尿素や被覆硝カルの<i>EF</i>はそれぞれ0.62%および0.23%で尿素(0.06%)よりも高い傾向にあり,被覆尿素および被覆硝カルの施用は尿素を分施するブロッコリー秋作体系においてN<sub>2</sub>O発生量を削減する効果は見られなかった.その原因として,生育前半の高温と多雨が被覆肥料Nの溶出とその後の硝化・脱窒におけるN<sub>2</sub>O生成を促進し,かつ生育後半に追肥で施用した尿素Nは低温と少雨のためN<sub>2</sub>O生成が少なかったためと考えられた.CN区では収量もC区と同程度に低く無機N溶脱量は最も多く,生育前半の多雨によるN溶脱が収量にも影響した可能性がある.以上より,尿素に代えて被覆尿素を用いる場合,肥料施用時期の気象条件によってはN<sub>2</sub>O発生量が増加する可能性があり,また被覆硝カルは収量低下や肥料N溶脱が増加することが懸念された.</p>

<p>Nitrous oxide (N<sub>2</sub>O) is one of the important greenhouse gases emitted from agricultural field. We investigated nitrous oxide (N<sub>2</sub>O) emissions following the application of coated urea (CU) and calcium nitrate in autumn broccoli cultivation field. The experiment was conducted in Ehime University Farm from September to November 2016 and comprised four treatments: non-fertilized (C), urea (U), CU, and coated calcium nitrate (CN) applications. In CU and CN treatments, we applied only 80% of the nitrogen (N) fertilizer used in treatment C; of this, 40% was replaced with coated fertilizer. We measured the N<sub>2</sub>O flux and N<sub>2</sub>O emission factor (EF) induced by applied N as well as soil environmental factors including soil temperature at 5-cm-depth, soil pH, and soil ammonium and nitrate concentrations. We also measured yield, concentration of N leaching from the top 20-cm soil layer, N uptake by plant, and N use efficiency. EFs of the CU (0.62%) and CN (0.23%) treatments were higher than that of the U (0.06%) treatment. Application of CU or CN instead of U did not reduce N<sub>2</sub>O emissions from the autumn cultivation of broccoli. In the early stages of the experiment, N elution from the coated fertilizer following nitrification and denitrification might have been enhanced due to higher temperatures and precipitation. In addition, N<sub>2</sub>O emission from the applied supplemental N was low because of lower temperature and precipitation conditions following the supplemental fertilization in U. Lower yield and higher levels of leached N in CN treatment may have been due to the loss of N with higher precipitation after basal fertilization. Our study demonstrates that application of coated U could increase N<sub>2</sub>O emissions relative to the application of U under higher temperature and precipitation conditions following the application. Furthermore, application of CN may decrease the yield and increase leaching of N.</p>

Journal

  • Japanese Journal of Soil Science and Plant Nutrition

    Japanese Journal of Soil Science and Plant Nutrition 89(4), 302-310, 2018

    Japanese Society of Soil Science and Plant Nutrition

Codes

  • NII Article ID (NAID)
    130007433192
  • NII NACSIS-CAT ID (NCID)
    AN00195767
  • Text Lang
    JPN
  • ISSN
    0029-0610
  • NDL Article ID
    029202076
  • NDL Call No.
    Z18-331
  • Data Source
    NDL  J-STAGE 
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