Plant Factory Using Artificial Light

Adapting to Environmental Disruption and Clues to Agricultural Innovation

Masakazu Anpo, Hirokazu Fukuda, Teruo Wada

• Publisher: Elsevier
• Year: 2018
• Print ISBN: 9780128139738
• eBook ISBN: 9780128139745
• Topic: Technologie et ingénierie
• Subtopic: Ingénierie de la chimie et de la biochimie

Plant Factory Using Artificial Light: Adapting to Environmental Disruption and Clues to Agricultural Innovation features interdisciplinary scientific advances as well as cutting-edge technologies applicable to plant growth in plant factories using artificial light. The book details the implementation of photocatalytic methods that ensure the safe and sustainable production of vegetables at low cost and on a commercial scale, regardless of adverse natural or manmade influences such as global warming, climate change, pollution, or other potentially damaging circumstances. Plant Factory Using Artificial Light is an essential resource for academic and industry researchers in chemistry, chemical/mechanical/materials engineering, chemistry, agriculture, and life/environmental/food sciences concerned with plant factories.- Presents an interdisciplinary approach to advanced plant growth technologies- Features methods for reducing electric energy costs in plant factories and increasing LED efficiency- Considers commercial scale operation

Part I

Efficient and Effective Vegetable Cultivation Technologies to Enhance Productivity and Quality

Section A

Fundamentals and Practices of Cultivation Technology

Chapter 1.1

Theory and Technology to Control the Nutrient Solution of Hydroponics

Teruo Wada Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Sakai, Japan

Abstract

Hydroponics is an essential technique in plant factory. Every plant is grown by supplying the nutrient solution which includes all essential elements with optimum composition and concentration for plant growth. It is important to keep nutrient composition and pH in the nutrient solution properly. Adjusting nutrient composition can be carried out by both analyzing the mineral concentrations in the nutrient solution and measuring the nutrient uptake by plants. In this chapter, the methods to adjust nutrient composition and pH of the nutrient solution in closed hydroponic will be introduced.

Keywords

Electric conductivity (EC); Essential elements; Hydroponics; Nutrient uptake; Nutrient composition; Nutrient solution; pH

Outline

• 1.1.1 Introduction
• 1.1.2 Nutrient Solution—Control System
• 1.1.3 Calculating Nutrient Uptake by Plants
  • 1.1.3.1 Principle of Yamazaki Formula in the Nutrient Solutions
  • 1.1.3.2 Application of Yamazaki's Method to Closed Hydroponic System
• 1.1.4 Management of Nutrient Concentration
• 1.1.5 Calculation Method for Adjusting the Nutrient Composition
• 1.1.6 Adjustment of pH
• 1.1.7 Conclusions and Prospects
• References

1.1.1 Introduction

Hydroponics is the cultivation methods of plants without any soils. Water culture such as NFT or DFT and substrate culture using some media such as rockwool or coconut-coir are included in it. All plant factories use hydroponic systems, because of (a) automatic control of irrigation and fertilization, (b) saving labor, (c) keeping cultivation environment clean, (d) enabling to make cultivation beds multilayer, and so on. Sixteen minerals are needed to grow plant healthy. The minerals are called essential elements. Nine elements such as C, H, O, N, P, K, Ca, Mg, and S are called major elements, and seven elements such as Fe, Cu, Zn, Mn, Mo, B, and Cl are called minor elements. Thirteen elements in them excluding C, H, and O, which are supplied from water and CO₂, are needed to supply to plants as fertilizer. In soil culture, only N, P, and K, which are called three major elements, are supplied to plant as fertilizer generally, and most of any other elements are supplied from soil naturally. Because hydroponics does not use any soil, all 13 elements must be supplied to plants as fertilizer. The cultivation fluids which contain these 13 elements as optimum ratio and concentration for plant growth are the nutrient solutions. In hydroponics, water and fertilizer which are essential to plants’ growth are supplied with nutrient solution. In this section, the basic theory and technique to control the concentration of major elements in the nutrient solution will be described.

1.1.2 Nutrient Solution—Control System

The nutrient solution in hydroponic system is usually controlled by EC (Electric Conductivity), which is an indicator of concentration and pH. For example, EC of Enshi-shoho nutrient solution, which is Japanese standard nutrient solution, is about 2.4 dS m^{− 1}, and EC for growing lettuce in the plant factory is usually controlled 1.2–1.6 dS m^{− 1}. So, almost half strength of Enshi-shoho is used for lettuce growth. pH is adjusted to around 6.0. pH should not be over 7.0 because this situation causes precipitation of Ion and Manganese. Basic system for controlling the nutrient solution in closed hydroponic system is described in Fig. 1.1.1. It consists of a solution tank, two kinds of stock solution (basically, calcium nitrate and others), acid and alkali (generally, 5 N phosphate and 5 N potassium hydroxide), level sensor, EC sensor, pH sensor, metering pumps for injecting every solution to the nutrient solution, irrigation system, and so on. A kind of disinfection system such as UV or ozone is also installed in a certain system. Basic procedure is below: (1) water level become low by plants’ absorption of water, (2) water is supplied to solution tank, (3) stock solutions are supplied until the EC become set value, (4) acid or alkali was added to the nutrient solution if it is needed. Analysis of concentrations of mineral elements in the nutrient solution is carried out periodically, but automatic control of the concentration of each mineral elements is not realized. So, adjusting the formula of the additional nutrient solution is carried out manually.

Fig. 1.1.1 Basic system for controlling the nutrient solution in closed hydroponics.

1.1.3 Calculating Nutrient Uptake by Plants

1.1.3.1 Principle of Yamazaki Formula in the Nutrient Solutions

Yamazaki formula is one of famous nutrient solution in Japan. The formula has many kinds of compositions which are suitable for growing each vegetable. Dr. Yamazaki measured the apparent concentrations of nutrient uptake by plants. The concentrations were measured by following procedure as shown in Fig. 1.1.2. Plants are grown in the bucket by aerated water culture until the volume of the nutrient solution become 70%–80% of start volume. Let a volume of the nutrient solution and a concentration of each element at the start of cultivation be w₁ and n₁, and a volume of the nutrient solution and a concentration of each element at the end of cultivation be w₂ and n₂, respectively. Apparent concentration of the nutrient uptake by plants (N/W) can be calculated as below:

$\frac{N}{W}=\frac{n_1\times w_1-n_2\times w_2}{w_1-w_2}$

(1.1.1)

Fig. 1.1.2 Principle of Yamazaki formula.

This is the principle of Yamazaki formula. Dr. Yamazaki thought that each plant has its own property of nutrient uptake. N/W of every major element was calculated under various conditions (e.g., some level of EC or pH, different plant ages, different season, and so on) and optimum compositions of nutrient uptake by many kinds of plant were published as Yamazaki formula [1]. It is t...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Contributors
• Introduction: Artificial Light-Type Plant Factories—Outline and a Vision for the Future
• Part I: Efficient and Effective Vegetable Cultivation Technologies to Enhance Productivity and Quality
• Part II: New Science and Technologies for Low Cost Production and IT Control Systems
• Part III: Various Technological Approaches and Business Strategies for Plant Factories
• Index