An analysis of optimal fertigation implications in different soils on reducing environmental impacts of agricultural nitrate leaching

Nasrin Azad,Vahid Rezaverdinejad,Fariborz Abbasi,Javad Behmanesh,Maryam Navabian

doi:10.1038/s41598-020-64856-x

Nasrin Azad, Vahid Rezaverdinejad + Show 3 more

Open Access

https://doi.org/10.1038/s41598-020-64856-x

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Abstract

Excessive and incorrect use of nitrogen (N) fertilizers in agriculture leads to high nitrate leaching to groundwater and harmful effects on the environment. The main objective of this research was to optimize the N fertigation scheduling for a surface micro-irrigation system in different soils. N uptake by corn and its losses were investigated for two fertigation scheduling scenarios including regional recommendation scheduling with three fertigation events and a weekly application schedule. The fertigation scheduling was then optimized to achieve both environmental objectives (minimizing nitrate losses) and corn N requirements (maximizing N uptake sufficiency). For this purpose, the HYDRUS-2D model, simulating water flow and N transport in soil, was linked to an optimization algorithm. In both scenarios, N uptake by plant was not adequate at different stages of growth in all three soil types, especially in the sandy loam soil. Optimization produced a decrease in nitrate leaching and an increase in N uptake as well as fully supplied plant requirements at different stages of corn growth. Optimization framework presented in this study and optimum fertigation scheduling in various soil textures can be applicable as a guideline for operators of micro-irrigation systems which reduce nitrate leaching and increase N uptake sufficiency.

Highlights

Excessive and incorrect use of nitrogen (N) fertilizers in agriculture leads to high nitrate leaching to groundwater and harmful effects on the environment
Deep percolation water losses and nitrate leaching during a weekly fertilizer cycle, which includes one irrigation event with a fertigation application and one without, are minimal in this soil type for these optimum decision parameters
The results of this study showed that the optimized fertigation schedules for three soil textures increased N uptake and provided sufficient N supply during different stages of the corn growth, as well as reduced nitrate losses in comparison with scenarios involving either regional recommendations for fertilizer applications or uniform weekly fertilizer applications

Summary

Introduction

Excessive and incorrect use of nitrogen (N) fertilizers in agriculture leads to high nitrate leaching to groundwater and harmful effects on the environment. The fertigation scheduling was optimized to achieve both environmental objectives (minimizing nitrate losses) and corn N requirements (maximizing N uptake sufficiency) For this purpose, the HYDRUS-2D model, simulating water flow and N transport in soil, was linked to an optimization algorithm. It should be possible to reduce the risk of groundwater contamination by nitrate without decreasing the crop yield by creating the balance between the N crop requirements and its efficient use by optimizing management strategies for water and N fertilizer applications in the field[3,4]. Different strategies for water and fertilizer management in agriculture have recently been investigated using numerical models simulating variably-saturated water flow and solute transport, as well as root water and nutrient uptake in soils. Ramos et al simulated water flow and N transport using HYDRUS-2D and indicated that high nitrate uptake occurred when the number of fertigation events was large, and the amount of applied fertilizer in each event was small[16]

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