Comparative Analysis of Energy and GHG Emissions Using Fixed and Variable Fertilization Rates

Marius Kazlauskas,Indrė Bručienė,Egidijus Šarauskis,Algirdas Jasinskas

doi:10.3390/agronomy11010138

Abstract

Reducing the overuse of mineral fertilizers in crop production is a key factor related to healthier soil, healthier food, and more economical, efficient, and cleaner agricultural production. The aim of this study was to investigate and to compare the effects of fixed and variable rate fertilization with fertilizer consumption, energy consumption, and environmental impact. A 4-year experimental field study using crop rotation of four plants (spring barley, winter oilseed rape, winter wheat, and faba bean) was performed. Fertilization with phosphorus and potassium at a variable rate were performed and applied based on the soil properties analyzed before the start of the research and completion of the fertilization maps. Nitrogen fertilization was performed by additional fertilization using a proximal N-sensor, which gives the accurate nitrogen uptake in plants in real-time. This was followed by a comparative evaluation analysis of variables and conventional fixed-rate fertilization methods to assess fertilizer consumption, energy consumption, environmental impact, and economic efficiency. The results of the study showed that an application of a variable fertilization rate can reduce the total amount of nitrogen, phosphorus, and potassium fertilizers by 24.9%, energy consumption by 3463.1 kg ha−1, and emissions of greenhouse gases (GHG) by 341.5 kg CO2eq ha−1 compared to fixed fertilization rate. The method of fertilization with a variable application rate reduced the costs of fertilization, and at the same time, the costs of the total plant production by €168.0 ha−1, on average.

Highlights

Plant nutrition is one of the most important factors on which the yield and the quality of agricultural products depend [1]
In 2018, global consumption of chemical and mineral fertilizers amounted to 188 million tons, of which nitrogen (N) averaged 58%, phosphorus (P2 O5 ) 22%, and potassium (K2 O) 21%
The aim of this work was to investigate and to compare the effects of two fertilization methods, i.e., fixed rate used in conventional farming practice and variable rate, applied after analyzing the soil and assessing the changes in fertilizer consumption, energy consumption, greenhouse gases (GHG) emissions, and economic costs related to fertilizers

Summary

Introduction

Plant nutrition is one of the most important factors on which the yield and the quality of agricultural products depend [1]. Intensive use of mineral fertilizers and application of conventional fertilization methods have negative effects on the soil, the environment, and human health. Variable rate fertilization (VRF) is essential for the implementation of precision farming and for the efficient use of mineral fertilizers and nutrient management in plants adapted to the conditions of individual field sites [5]. It should be taken into consideration that the application of VRF usually requires prior knowledge of the field characteristics. This method often relies on accurate soil sampling and/or monitoring and analysis of crop yields for a specific field site [6]

Objectives

Results

Conclusion