Journal article

Publication year: 1985

Pages: 403-413

Journal: Plant and Soil

Volume number: 86

Issue number: 3

ISSN: 0032-079X

eISSN: 1573-5036

DOI Link: https://doi.org/10.1007/BF02145461

Publisher: Springer

Abstract: 
The importance of initial exchangeable soil NH4+ in N nutrition and grain yeild of rice was studied in a number of representative lowland rice soils in the Philippines. The initial exchangeable soil NH4+ + fertilizer N plotted against N uptake by the crop resulted in a highly significant linear relationship (R2 = 0.91), suggesting that the presence of exchangeable NH4+ in the soil at transplanting behaved like fertilizer N. The correlation between N fertilizer rate and N uptake by the rice crop was relatively poor (R2 = 0.73). On the other hand, relative grain yield was more closely correlated with the initial exchangeable soil NH4+ + fertilizer N than with fertilizer N applied alone. The initial exchangeable NH4+ in the soil apparently contributed substantially to the N uptake of the crop. Critical N levels in the soil defined as the initial exchangeable soil NH4+ + fertilizer N at which the optimum grain yield (95% of the maximum yield) is obtained, varied from 60-100 kg N/ha in the wet season and from 100-120 kg N/ha in the dry season for the different fertilizer treatments. The initial exchangeable soil NH4+ should serve as a guide in selecting an optimum N fertilizer rate for high grain yields.

Harvard Citation style: SCHON, H., MENGEL, K. and DEDATTA, S. (1985) THE IMPORTANCE OF INITIAL EXCHANGEABLE AMMONIUM IN THE NITROGEN NUTRITION OF LOWLAND RICE SOILS, Plant and Soil, 86(3), pp. 403-413. https://doi.org/10.1007/BF02145461

APA Citation style: SCHON, H., MENGEL, K., & DEDATTA, S. (1985). THE IMPORTANCE OF INITIAL EXCHANGEABLE AMMONIUM IN THE NITROGEN NUTRITION OF LOWLAND RICE SOILS. Plant and Soil. 86(3), 403-413. https://doi.org/10.1007/BF02145461