Organic Fertilization of Growing Media: Response of N Mineralization to Temperature and Moisture

Patrice Cannavo,Louise Paillat,Matthieu Valé,Mohammed Benbrahim,Sylvie Recous,Sophie Bresch,René Guénon

doi:10.3390/horticulturae8020152

Abstract

Managing plant fertilization is a major concern of greenhouse growers when it comes to sustainable production on growing media. Organic fertilization is popular, but more difficult to control since organic compounds first need to be mineralized by microbes. The objective of this study was to characterize the time course of N mineralization by different fertilizer–growing media pairs, in the absence of plants. Several incubations were carried out at four temperatures (4, 20, 28, and 40 °C) and three suction potentials (−3.2, −10, and −31.6 kPa) on four growing media under two organic fertilization conditions to study the dynamics of NH4+ and NO3− production. The results showed that the release of mineral N was strongly dependent on growing media, temperature, humidity, and fertilizer nature, varying from 10.7% to 71.3% of the N fertilizer applied. A temperature action law was established for the four growing media. The Q10 value of the growing media was 1.13, lower than the average Q10 value of arable soils. On the other hand, the specific behavior of the growing media did not yield a single humidity action law. Nevertheless, the nitrification process, evaluated by analyzing the ratio of NO3− to total mineral N, showed a humidity-dependent relationship common to the four growing media and comparable to admitted observations on soils. Nitrification was optimal when growing media humidity was higher than 0.46 v/v.

Highlights

Publisher’s Note: MDPI stays neutralConsumers are concerned about food quality and the environmental impact of its production
(GM × Temp × Hum: F > 1.7, p < 0.001, between effect). We focused on these interaction factors to present our results
The N mineralization dynamics of two organic fertilizers in four growing media types at different temperature and humidity conditions showed a strong impact of the different treatments on NH4 + and NO3 − release

Summary

Introduction

Publisher’s Note: MDPI stays neutralConsumers are concerned about food quality and the environmental impact of its production. The subject is thorny in horticulture, in soilless production which consumes resources (water and other inputs). Producers are moving toward agro-ecological practices such as organic fertilization and the development of growing media from renewable organic materials [1]. In conventional soilless production (cultivation in pots and containers), the plant grows in a finite volume of a growing medium with limited buffering capacity for water, temperature, and pH in particular [2]. The physical, chemical, and, to a lesser extent, biological properties of growing media materials have been investigated over the last 40 years, but practical considerations have been relatively little investigated [3]. Professionals have good knowledge of the physicochemical properties of the growing media, allowing for the control of irrigation and mineral fertilization. Introducing organic fertilizers requires with regard to jurisdictional claims in published maps and institutional affiliations

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