Cycling of Micronutrients in Terrestrial Ecosystems

Abstract

Through their involvement in various enzymes and other physiologically active molecules, micronutrients are important for gene expression; biosynthesis of proteins, nucleic acids, growth substances, chlorophyll and secondary metabolites; metabolism of carbohydrates and lipids; stress tolerance, etc. Micronutrients are also involved in structural and functional integrity of membranes and other cellular components (Rengel 2003).Millions of hectares of arable land in the world have low availability of micronutrients (White and Zasoski 1999). On such soils, growth and yields of crops and pastures are reduced (e.g. Cakmak et al. 1996), and supplementation with micronutrients in the form of fertilisers or organic amendments may increase crop growth.Food production in most countries results in depletion of soil nutrient reserves. Calculations for macronutrients show a world average depletion (in kg ha -1 year -1 ) of 12 for N, 5 for P and 20 for K (Sheldrick et al. 2002). Unfortunately, similar budgets are not available for micronutrients; however, offtake of micronutrients is generally small, and the total amounts in soils may be sufficient for a large number of crops (potentially hundreds to thousands) (e.g. Graham 1984).Voluminous literature exists on cycling of macronutrients in agroecosystems (e.g.

FERTILIZACIÓN CON BORO EN PLANTACIONES DE Eucalyptus urophylla S. T. Blake en TABASCO

“…Dichas plantaciones se perciben como una solución ambiental alterna deseable, cuando el aprovechamiento de los bosques naturales (especialmente de edad madura) no garantiza la conservación del recurso forestal ni beneficios socioeconómicos sostenidos para las comunidades (Rivera, Fierros, Vázquez, Gómez, & Velázquez, 2008). Por tanto, las PFC (en particular, las de turno corto) se manejan como sistemas intensivos y reciben un aporte nutrimental importante por medio de fertilizaciones (Rengel, 2007), aunque los métodos intensivos puedan conducir al agotamiento de la fertilidad del suelo y a problemas nutrimentales permanentes (Pritchett, 1990). Por otro lado, la productividad de los sistemas forestales está relacionada con una serie de factores ambientales que comprenden la radiación solar, temperatura y agua, así como la disponibilidad y absorción de nutrientes; esta última sigue siendo un factor crítico en los sistemas intensivos (Binkley, 1993).…”

“…These plantations are perceived as a desirable alternative environmental solution, when the logging of natural forests (especially old growth ones) does not ensure either the conservation of forest resources or sustained economic benefits for communities (Rivera, Fierros, Vázquez, Gómez, & Velázquez, 2008). Therefore, CFPs (particularly those of short rotation) are managed as intensive systems and receive an important nutrient input through fertilization (Rengel, 2007), although such intensive methods can lead to loss of soil fertility and permanent nutrient problems (Pritchett, 1990). On the other hand, the productivity of forest systems is related to a number of environmental factors including solar radiation, temperature and water, and nutrient availability and uptake; the latter continues being a critical factor in intensive systems (Binkley, 1993).…”

Profile distribution of micronutrients in an aquic brown soil as affected by land use

“…Micronutrient availability to plants can be measured in direct uptake experiments, or estimated with techniques that correlate quantities of micronutrients extracted chemically from soils (White andZasoski 1999, Kabata-Pendias 2001). Millions of hectares of arable land in the world have low availability of micronutrients, and many of these deficiencies were brought about by the increased demands of more rapidly growing crops for available forms of micronutrients (Rengel 2007, Alloway 2008). Micronutrient cycling is quite different among various terrestrial ecosystems (Rengel 2007), and land use changes may strongly affect their distributions in agro-forestry ecosystems (Eneji et al 2003, Venkatesh et al 2003, Jiang et al 2005a, Han et al 2007.…”

Soil properties determine the elevational patterns of base cations and micronutrients in plant-soil system up to the upper limits of trees and shrubs

“…In this study, negative correlations between soil C:N and base cations ( (Cremer and Prietzel, 2017). Therefore, significant negative correlations were detected between soil NO 3 -and base cations in this study ( A negative correlation between soil pH and soil available micronutrients (Table 3) might be due to precipitation of micronutrient cations at higher soil pH (Rengel, 2007).…”

“…However, little attention has been paid to base cation and micronutrient availabilities as well as their inputs and outputs under changing environmental conditions (Rengel, 2007). 65 The plant distribution along elevational gradients reflects changes in environmental conditions (Li et al, 2003(Li et al, , 2004(Li et al, , 2008aZhu et al, 2012a,b).…”