About Us | Help Videos | Contact Us | Subscriptions
 

Abstract

 

This article in SSSAJ

  1. Vol. 48 No. 2, p. 291-294
     
    Received: Jan 19, 1983
    Published: Mar, 1984


 View
 Download
 Alerts
 Permissions
 Share

doi:10.2136/sssaj1984.03615995004800020012x

The Release of Nonexchangeable Ammonium (15N Labelled) in Wetland Rice Soils1

  1. G. Keerthisinghe,
  2. K. Mengel and
  3. S.K. De Datta2

Abstract

Abstract

The release of nonexchangeable (fixed) NH+4 was studied for three representative rice soils of the Philippines. Soil samples from these soils were treated with 15NH+4 in the laboratory so that they contained appreciable amounts of nonexchangeable NH+4 in 15N form. Special soil holders were filled with the labelled soil and incubated in the wetland rice soils from July to October at a depth of 0.2 m. During this period of incubation, highly significant amounts of labelled nonexchangeable NH+4 were released from all three soils. For the Maligaya silty clay loam and Guadalupe clay, both containing vermiculite, the total release of nonexchangeable NH+4 was higher than the release of labelled nonexchangeable NH+4 showing that non-labelled NH+4 was released as well. 15N analysis of the rice plants showed that the nonexchangeable labelled NH+4 was subsequently available to the crop. Assuming a soil bulk density of 1 and a rooting depth of 0.2 m release of nonexchangeable NH+4 from the Maligaya silty clay loam ranged from 80 to 100 kg N ha−1, while for the Guadalupe clay and Santa Rita clay the net release of nonexchangeable NH+4 amounted to about 20 to 40 kg N ha−1, respectively. It is concluded that nonexchangeable NH+4 may play a major role in N nutrition of rice crops grown in wetland rice soils rich in vermiculite.

  Please view the pdf by using the Full Text (PDF) link under 'View' to the left.

Copyright © . Soil Science Society of America