Comparison of characteristics of new biodegradable chelating agents

Abstract

Micronutrients serve many roles in plant metabolism and growth. However their deficiencies have been verified in many soils. Thus the use of micronutrient fertilizers which supply plants with necessary micronutrients determines proper and efficient plant growth. In fertilizers technology these compounds are enclosed by chelating agents. Nowadays pressure is mounting for the removal and replacement of non-biodegradable chelating agents with alternative, readily biodegradable chelates. In this paper characteristics of new biodegradable chelating agents – a potential substitutes for insufficiently biodegradable ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) – are presented.
Authors: Jakub SKUT, Magdalena BOROWIEC, Krystyna HOFFMANN, Józef HOFFMANN

1. INTRODUCTION

1.1. GLOBAL FERTILIZER DEMAND

According to International Fertilizer Industry Association summary report, income growth of GDP (gross domestic product) in emerging economies stimulates food diversification towards more meat, fish, fruits, vegetables, sugar and vegetable oils and less cereals and pulses per capita. More meat production will require greater amounts of coarse grains and oilseed meals thus trigger fertilizer demand. Record high oil prices have a dual effect on fertilizer demand: they impact fertilizer prices on one hand and they stimulate biofuel production (nowadays one of the main key drivers of world fertilizer consumption) on the other hand [2].

1.2. MICRONUTRIENTS AND FERTILIZERS

Micronutrients (Fe, Mn, Zn, Cu, B, Mo, Cl, Ni) are as important as the primary and secondary nutrients in plant nutrition. However, the amounts of micronutrients required for optimum nutrition are much lower. Micronutrient deficiencies are widespread because of increased nutrient demands from the more intensive cropping practices [3, 5]. Micronutrient deficiencies have been verified in many soils. Furthermore they occur in soil in forms which are unavailable for uptake by plant. Thus numerous micronutrient fertilizers are on the market. These sources are classified as inorganic, synthetic chelates, natural organic complexes, and fritted glasses. Chelated micronutrients are widely used in agriculture and are strongly promoted by the fertilizer industry [3].

1.3. CHELATED MICRONUTRIENTS

Chelates are useful for micronutrients applied to different kind of soils. Iron, manganese, zinc and copper react with the ions in fertilizers (e.g. macronutrients) and form insoluble substances. As a result, the nutrients are made unavailable to plants. The organic coating in the chelate prevents these reactions from occurring in the soil. The plant roots take up the chelated nutrient and the chelate releases the nutrient within the plant [10].

Chelated nutrients are also useful for foliar application. Plant leaves have a waxy coating that prevents them from drying. The wax repels water and inorganic substances making it difficult for inorganic nutrients to penetrate into the leaf. However, organic molecules like chelating agents can penetrate the wax [5, 10].