Ammonium nitrogen increases Ca uptake from non-exchangeable reservoirs by eucalypt plants

Author(s)

dos Santos, Mateus Alves ^[1] ; Valadares, Rafael Vasconcelos ^{[2, 3, 4]} ; Lima Neves, Julio Cesar ^[5] ; da Silva, Ivo Ribeiro ^[5] ; Totola, Marcos Rogerio ^[3] ; Costa, Mauricio Dutra ^{[3, 6]}

Affiliation

^[1] Univ Fed Vicosa, Dept Fitotecnia, BR-36570900 Vicosa, MG - Brazil

^[2] Univ Estadual Campinas, Nucleo Interdisciplinar Planejamento Energet, BR-13083730 Campinas, SP - Brazil

^[3] Univ Fed Vicosa, Dept Microbiol, BR-36570900 Vicosa, MG - Brazil

^[4] Fundacao Amparo Pesquisa Estado Sao Paulo FAPESP, BR-36570900 Sao Paulo, SP - Brazil

^[5] Univ Fed Vicosa, Dept Solos, BR-36570900 Vicosa, MG - Brazil

^[6] CNPq, CONICET, Brasilia, DF - Brazil

• Document type: Journal article
• Source: FOREST ECOLOGY AND MANAGEMENT; v. 465, JUN 1 2020.
• Web of Science Citations: 0

Abstract

Eucalypt plants can take up calcium (Ca) from soils with nondetectable levels of exchangeable Ca2+. This suggests the operation of unknown processes capable of rendering non-exchangeable forms of the nutrient available to eucalypts. An explanatory hypothesis for this phenomenon is that soil acidification by ammonium can release Ca from Ca-oxalate and soil minerals. Therefore, the objective of this work was to study the interactions between Ca-oxalate and ammonium on Ca and N nutrition of a Eucalyptus grandis x Eucalyptus urophylla hybrid (Eucalyptus urograndis) in a soil with nondetectable exchangeable Ca2+. For this, E. urograndis seedlings (clone AEC 144) were grown in pots with soil fertilized with the combination of five Ca doses (0, 0.10, 0.20, 0.40, and 0.80 cmol(c)/kg) as Ca-oxalate, and five N doses (0, 25, 50, 100, and 200 mg/kg) as NH4Cl. The experiment was conducted in a greenhouse for 60 days. Two additional experiments were conducted to verify the stability of Ca-oxalate at different doses in the soil along an incubation time of 60 days and at different soil pH. E. urograndis dry matter production and Ca and N uptake were highly dependent on ammonium applied to the soil, but only slightly influenced by Ca-oxalate. When no Ca-oxalate was added, Ca from a non-exchangeable source was transferred to E. urograndis. This transfer increased with increasing ammonium supply, stabilizing at the highest N dose applied. Ca-oxalate solubilization in the soil without E. urograndis plants ranged from 62 to 94% after 60 days of soil incubation and the release of Ca from Ca-oxalate did not change as a function of pH. In general, the release of Ca from Ca-oxalate presented two behaviors: pH-independent (trial without plants) and pH/NH4+-dependent (trial with plants). This is the first report demonstrating that ammonium lead to the mobilization of non-exchangeable Ca reservoirs by E. urograndis plants cultivated in a soil with no exchangeable Ca. (AU)

• FAPESP's process: 18/24707-0 - Assessing the effects of integrated crop-livestock systems and associated management practices on soil carbon and nitrogen cycling processes using the Daycent model
• Grantee: Rafael Vasconcelos Valadares
• Support Opportunities: Scholarships in Brazil - Post-Doctoral