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No.21 (1974/12) >

 
Title :ジャーガル土壌におけるサツマイモ収量におよぼす窒素とりん酸の肥効(農芸化学科)
Title alternative :Effects of nitrogen and phosphorus on the yield of sweet potato grown on a calcareous clayey soil of Okinawa (Department of Agricultural Chemistry)
Authors :大屋, 一弘
Authors alternative :Oya, Kazuhiro
Issue Date :1-Dec-1974
Abstract :沖縄本島の稲嶺統土壌(ジャーガル土壌の1種)にサツマイモ(品種 : ナカムラサキ)を1972年と1973年の2回にわたり秋植栽培し, 窒素・りん酸・在圃期間などが, 塊根およびかずら収量・でん粉含量・でん粉収量などにおよぼす効果を調べた。カリ(K_2O)は全実験区一様に10a当たり7.0kgの割合で施用したが, 窒素(N)は0,3.5,7.0kgの3段階, りん酸(P_2 O_5)は3.5,7.0kgの2段階, 在圃期間は4カ月および5カ月とし, これら3因子を組合せた実験を行なった。実験前の土壌の養分含量は表土および心土において, それぞれ全窒素0.10,0.11%, 有効態りん酸3.1,13.4mg/100g, 置換性カリ0.54,0.31ml/100gであったが, 塊根収量に対しては窒素施用の効果があり, りん酸の多少および在圃期間の長短による効果はみられなかった。かずら収量は塊根収量と密接な相関関係を示した。でん粉含量は平均22.68%であったが, 処理区間に大きな相違がみられず, そのためでん粉収量には窒素による塊根増収の傾向が反映された。結果としてこの実験の範囲では, 供試土壌が上記程度の養分を含むとき, 秋植サツマイモの塊根およびかずら収量, でん粉収量などを増加させるためには10a当たり窒素7.0kg, りん酸3.5kg施用が適当であり, 在圃期間は4カ月でも良いと考えられた。
A variety of sweet potato (Ipomoea batatas L.) was grown on a calcareous clayey soil of Okinawa Island in order to investigate the effects of nitrogen, phosphorus, and growth period on the starch content and the yields of root tuber, vine, and starch. Nitrogen was applied in three levels of 0,3.5,and 7.0kg N/10 are, and phosphorus in two levels of 3.5 and 7.0kg P_2O_5/10 are with thorough application of potassium as much as 7.0kg K_2O/10 are. Ammonium sulfate, superphosphate and potassium chloride were used as the source of nitrogen, phosphorus, and potassium, respectively. Sweet potato seedlings were planted in August of 1972 for the first experiment and harvested four and five months later. The experiment was run in randomized complete block design with three replications. The second experiment in 1973 was run in the same manner as in the first one succeeding the same treatment plots, but with an exception that the second one had only two replications. The root tuber significantly increased in the yield of two years average with the increasing amounts of nitrogen applied but not with phosphorus and growth period when the initial nutrient contents of the farm soil were 0.1% in total nitrogen and 3.1mg per 100g of the surface soil in available phosphorus. The yield of vine showed a close correlation with the root tuber yield. The starch content was 22.68% in average without much deviation regardless the treatments of nitrogen, phosphorus, and growth period. Because of this tendency, the starch yield, which was obtained by multipling the root tuber yield by the starch content, showed a similar trend to the yield of root tuber which demonstrated the effect of applied nitrogen only. As an overall result, the autumn crop of sweet potato yielded best by the applications of 7.0kg N, 3.5kg P_2O_5 and 7.0kg K_2O per 10 are with 4 months of the growth period in the present experiment on this particular soil. The maximum yield of the root tuber obtained here was only 1.7t/10 are, being much lower than those obtained elsewhere. Accordingly, further studies must be done to bring out higher productions on the pertinent amount of nitrogen to be applied, the mineralization of soil nitrogen in organic forms and the fixation problem of phosphorus as well as nitrogen and potassium.
Type Local :紀要論文
ISSN :0370-4246
Publisher :琉球大学農学部
URI :http://hdl.handle.net/20.500.12000/4366
Citation :琉球大学農学部学術報告 = The Science Bulletin of the Faculty of Agriculture. University of the Ryukyus no.21 p.99 -107
Appears in Collections:No.21 (1974/12)

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