本省兩期作水稻之氮素營養比較

Abstract

本省之兩期稻作，無論是在不氮肥施用量，氮肥分施，密植栽培及一般推廣品種栽培情形之下，第二期作都比第一期作減產。第二期水稻之氮素濃度比第一期作較高，氮肥之吸收率亦不差，但水稻所吸收之氮素量大用為於稻藁之生長。所以水稻之氮素吸收並不是第二期作稻否產量之限制因素，即水稻氮素營養不是第二期稻作減產之原因。 The cause of lower yield of rice in the second crop than in the first crop has been a subject which attracts agricultural scientists in Taiwan. It is generally recognized that less tiller number, less total dry matter production, lower grain/straw ratio and lower grain yield are found in the second crop than in the first corp.