Nutrient dynamics and uptake of rice in irrigated lowland soils of agusan del norte subjected to episodic flooding

Abstract

© 2019, International Society for Southeast Asian Agricultural Sciences. All rights reserved. The dynamics of N, P, K, Ca and Mg in irrigated lowland soils subjected to episodic flooding and uptake of these nutrients at different growth stages were evaluated in Agusan del Norte, Philippines to address the recurring and persistent problems of nutrient deficiencies resulting in poor crop growth and subsequently low yield. The study was conducted at PhilRice – Agusan Experiment Station for two cropping seasons from June 2017 to March 2018. Five fertilizer treatments were laid out in randomized complete block design and crops were managed following the PalayCheck® system. Nutrients such as N, P, K, Ca and Mg both in soil and plant tissue were collected at various growth stages and analyzed in the laboratory. Unlike N and P, K is the most dynamic in the soil when subjected to flooding. The medium to high level of exchangeable K inherent in the soil can drop to a critical level during flooding but could rise to optimum level after the flooding episodes. Soil total N and available P are high and less affected by flooding incidents. The exchangeable Ca and Mg are very high and resulted in a very wide (Ca + Mg):K ratio of 176:1 and Mg:K ratio of 86:1. The wide exchangeable Mg:K ratio and very low exchangeable Ca:Mg ratio in the soil significantly reduced Mg content at all growth stages, far below the critical limit for rice. Discovering K – induced Mg deficiency in irrigated lowland rice in Agusan del Norte is the breakthrough of this study. Thus, further study on soil K and Mg interactions and their management should be prioritized.

Source or Periodical Title

Journal of the International Society for Southeast Asian Agricultural Sciences

ISSN

8593132

Page

31-44

Document Type

Article

Subject

Flooding episodes, Imbalanced cations, Nutrient absorption, Nutrient management

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