Current crop growth models, whether process-based or data-driven, rarely incorporate spectral light composition, limiting their applicability in highly controlled environments such as vertical farming. This work enhances the predictive performance of a well-established process-based lettuce growth model by exploiting existing experimental evidence on the role of light spectrum in plant development. To this end, we introduce a parameter gamma, modelled as a function of key spectral features (i.e. the Blue:Red and Far-Red:Red ratios), selected through machine-learning techniques. The resulting adjusted model (aVH opt) is then validated on an independent literature dataset, showing a substantial reduction in prediction error compared to the reference model, with a more than 60% decrease in RMSE. The application of the aVH opt model to a commercial dataset confirms its capability to capture key spectral effects, but also reveals its sensitivity to environmental and biological variability not fully accounted for in the current formulation.

In greenhouses, fossil CO2 is commonly used to increase crop yield. Regardless of future availability, which is expected to decrease, fossil CO2 enrichment is unsustainable. However, without CO2 enrichment, yields per unit area may decrease, increasing the energy intensity of produce. Non-fossil (‘short-cycle’) CO2 may prevent this, but its provision also requires energy. Here, CO2 sources are quantified from an energy perspective, using a new methodology applied to three sources: (1) biogenic CO2, (2) direct air capture (DAC), and (3) ambient CO2 from ventilation. The energy demand of CO2 has two aspects: (1) a ‘fixed’ aspect, from generating or supplying the CO2, and (2) a weather-dependent aspect, from heating displaced air in the greenhouse. Both affect the environmental impact of CO2 enrichment, depending on the carbon intensity of the energy source. Approximately 1% volumetric CO2 concentration is sufficient to make weather-dependent energy demand negligible, which makes greenhouses an interesting destination for biogenic CO2. The implications of non-fossil CO2 are calculated using year-long simulations, comparing the three sources' effect on yield and energy intensity of produce. Efficiency and the potential to increase it are investigated with Lorenz curves, revealing that most additional yield comes from a small minority of CO2 introduced into the greenhouse. This study consistently showed the following: the role of ambient ventilation in CO2 provision is minor, the energy efficiency of DAC should be prioritised rather than high outgoing CO2 concentrations (>1%), and biogenic CO2 is an energetically favourable option to be explored depending on locally available sources.

Determinate dwarf tomato has emerged as a crop with significant potential to be cultivated in a wide range of production systems, from open fields and simple tunnels to advanced vertical farms. However, there is currently only limited, cultivar-specific information available on its growth and development, and no dedicated crop models exist to support the selection of optimal production systems and/or climate set-points. Existing tomato models focus on large-fruited, indeterminate cultivars and on nearly optimal temperature ranges, which limits their validity for determinate dwarf cultivars in diverse climates. The aim of this study is to build, calibrate, and validate a crop model that simulates the yield of determinate dwarf tomato plants as a function of indoor air temperature, CO2 concentration, and photosynthetically active radiation (PAR). Two experiments in controlled-climate chambers were performed with two dwarf tomato cultivars to assess crop responses and thus adapt an existing indeterminate tomato model, calibrate and validate the new crop model. The adapted crop model reasonably predicted yield responses under a range of sub- and supra-optimal temperatures and daily light integral (DLI) conditions. The crop model was then integrated with a greenhouse-climate model and validated with a separate dataset from a greenhouse experiment, providing a powerful decision-support tool for designing and managing controlled-environment systems for varying climate regions worldwide.

[This corrects the article DOI: 10.3389/fpls.2020.592171.].

Vertical farming (VF) is a type of farming system where crops are cultivated in enclosed and sunless environments, offering a high level of precision and control of the crop environment. Several recent reviews have highlighted VF as a potential solution to global challenges like population growth, urbanization and climate change, thanks to land conservation, sustainability, reduced water usage, enhanced food safety, and shorter supply chains. This review critically analyses claims regarding the sustainability and other proposed benefits of VF, by focusing on what is known about crop energy budgets and productivity. It makes evident that staple crops, vital for calorie intake, cannot be economically grown in VF. Nonetheless, leafy vegetables can and are grown in VF. Based on existing literature, VF's annual production potential and its associated electricity consumption are quantified here. Figures about electricity production demonstrate that it is doubtful that urban VF production is more climate-smart than transport from far away. Even in a future world of green (but not unlimited) electricity, there will be a need for balancing grid usage, which does not fit well with the electricity craving of VFs. A review of pro and cons of growing systems of increasing technology content, shows that reduction of water use and of chemical emissions can be attained as well in greenhouses, without the environmental impact of the electricity consumption associated to VF. It is indeed wishful thinking that there is no environmental cost to getting rid of (free and non-polluting) sun light, even for the very best lighting fixtures. VF may have potential for niche crop production, or be employed for other practical reasons. However, this review challenges the claim that VF production is inherently more environmentally friendly than conventional agriculture.

This book provides an integrated approach to crop growth and development and the technical aspects of greenhouse cultivation and climate management. It combines an analysis of the relationship between crop production and ambient climate with an explanation of the processes that determine the climate in a protected environment. With the ability to modify the environment comes the need for growers to strike a balance between the costs and benefits of technology. This book outlines the methods and gives several examples of how to make 'optimal' choices about technology. Sustainable management of shoot and root environment is discussed, as well as the pros and cons of vertical farming. The processes addressed in this book, like crop growth, energy balance and mass exchange, apply to any kind of greenhouse. Therefore, in spite of the word 'technology', this is not a book about high-tech greenhouses only. 'Greenhouse horticulture' is an easy-to-read textbook for all those interested in protected cultivation, from university students and teachers to professional advisers in the field and managers of horticultural companies. Also available as E-book see greenhouse-horticulture-second-edition For more information about the e-book, please contact Sales.

BackgroundControlled environment agriculture, particularly vertical farms (VF), also called plant factories, is often claimed as a solution for global food security due to its ability to produce crops unaffected by weather or pests. In principle, essential macronutrients of the human diet, like protein, could technically be produced in VF. This aspect becomes relevant in the era of protein transition, marked by an increasing consumer interest in plant-based protein and environmental challenges faced by conventional farming. However, the real question is: what does the cultivation of protein crops in VF imply in terms of resource use? To address this, a study was conducted using a VF experiment focusing on two soybean cultivars.ResultsWith a variable plant density to optimize area use, and because of the ability to have more crop cycles per year, protein yield per square metre of crop was about eight times higher than in the open field. Assuming soy as the only protein source in the diet, the resources needed to get total yearly protein requirement of a reference adult would be 20 m2 of crop area, 2.4 m3 of water and 16 MWh of electricity, versus 164 m2, 111 m3 and 0.009 MWh in the field.ConclusionsThe study's results inform the debate on protein production and the efficiency of VF compared to conventional methods. With current electricity prices, it is unlikely to justify production of simple protein crops in VF or promote it as a solution to meet global protein needs. (c) 2024 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Recirculating hydroponic fertigation as used in high-tech greenhouses is over 95

Greenhouse horticulture grows increasingly important due to its ability to provide a controlled microclimate which is optimizable for highly efficient crop growth and resource use, although it may come at a significant energy and investment cost. One of the most crucial inputs in any greenhouse is sunlight, giving free energy and light for greenhouse crop growth. However, it is enormously variable, both geographically and seasonally. This review discusses materials and technologies usable in greenhouse cover and screen materials which can passively manipulate the incident sunlight to transmit a light spectrum that is ideal for crop growth, thereby improving the yield, and for greenhouse microclimate management, thereby reducing the energy usage of greenhouses. The current status of spectrum‐manipulating technology in greenhouses, developments over the last few years, some potential innovations adaptable from diverse fields to greenhouse horticulture, and the associated challenges, are discussed.

Cultivation and breeding of legumes as protein sources in the human or animal diet could benefit from accurate, rapid, and non-invasive measurements of protein content. A study was conducted into the feasibility of a fully non-invasive, in vivo protein measurement methodology applied to soybean (Glycine max. L.). The proposed methodology works by recording spectral images of the soybean pods in the visible and near-infrared (Vis-NIR), a rule-based segmentation approach, and partial least squares (PLS) regression to predict the crude protein content of the beans contained within the imaged pods. Using all 150 channels of the spectral camera, a model could be calibrated with a mean absolute precision error (MAPE) of 4.8 % (R2 = 0.92). Applying a tailored feature elimination approach to select only eight spectral bands and degrading the spectral resolution to 25 nm yields a model with a MAPE of 6.0 % (R2 = 0.88), indicating the potential for multispectral cameras in this application.

Recent studies concerning the integration of agricultural practices in cities demonstrated that Urban Agriculture (UA) can boost new sustainable urban developments. New technologies allow to integrate soil-less cultivation in- and on- mixed-use buildings, creating new synergies between the built environment and the urban food system. Accordingly, resource flows from buildings are an untapped opportunity for the creation of circular urban metabolisms that rely on recycling waste as input for food production systems. On this trail, this research work focuses on evaluating the feasibility of using urine and greywater streams as nutrient solution in a theoretical model of Building-Integrated Agriculture (BIA) located in Amsterdam. Results showed that it is feasible to use urine and greywater as nutrient solutions (NS). However, treated urine showed higher concentration of macronutrients compared to fertilizer recipes found in literature, and therefore needed to be diluted with increasing amount of greywater to match either N or P concentration. Accordingly, P deficiencies in the plants or excessive N concentration were found in the final wastewater-based NS. Future research is highly recommended to assess the quality of plants grown in BIA systems as well as the possible content of harmful viruses and bacteria in the harvested produce.

Within the public-private collaboration project Smart Materials, electrochromic glasses (EC glass, able to instantaneously switch light intensity or scattering) were evaluated on their potential for production of high value ornamental crops that are assumed to benefit from relatively low sunlight levels. Growers use shading screens or temporary coatings on glass during the summer, which react slowly to changing outside light conditions. EC glass allows timely light intensity control and therefore more constant light conditions. Experiments were carried out with pot Anthurium and Schefflera. Research questions were: Is EC glass able to control light intensity to a constant level with changing outside sunlight conditions? Does this improve crop growth and quality? The light levels were well controlled under EC glass. As a result, the plants were exposed to a higher light sum attained by more constant light, less peaks on sunny days and more light on clouded days. However, this did not translate into faster growth, more flowers nor better plant quality. The achieved light control advantage by the EC glass was counteracted by the thermal radiation behavior of the glass: light was absorbed, which lead to high glass temperatures, thus high leaf temperatures. That lead to stomata closure and lower photosynthesis efficiency during sunny periods. More research is needed to evaluate the potential of smart glasses as greenhouse covers for high value crops.

The rapid urban growth seen globally in recent years has not been supported by a simultaneous increase in agricultural land and/or crop productivity. Producing crops in (peri-)urban areas shows good potential to provide the vegetable products for a healthy and balanced diet for the growing population, but it has to deal with the local availability of resources. Thus, meeting the food requirements of the urban population as efficiently and robustly as possible is a challenge. This study developed a methodology to estimate the use of resources of urban farming systems to produce energy- and nutrient-dense vegetables capable of meeting human dietary needs. The method was applied to two extremely different cultivation systems (an open field farm and a plant factory with artificial lighting) for the production of seven crops. The results on the resource efficiencies to meet the annual per-capita vegetable requirements are discussed in relation to crop type, local climate and cultivation system. The application of this methodology can support farmers' decisions on the choice of crops and the type of urban farming systems that are most efficient in contributing to a plant-based diet. The results can also be translated into water, energy, and surface area needed to meet the nutritional requirements at a city-regional level.

Reducing environmental impact is a necessary condition for sustainability, but it is not a sufficient one. The current ‘linear’ economy not only leads to environmental impact; it also depletes finite natural reserves. This is why moving towards a more ‘circular’ economy is desired. One of the obstacles in implementing a circular economy are knowledge gaps about the nature and quantity of input and output flows of production processes. The aim of this paper is not to quantify environmental impact, but rather to bridge these knowledge gaps for a particular type of vegetable production, by detailing the resource input and output of a typical high-tech glasshouse tomato crop in the Netherlands. In particular, this paper has focused on material flows potentially suitable for relatively short-term re-use and/or substitution in a circular economy. The paper describes how figures have been collected about the sub-processes involving each of the material flows, the accuracy and range of such numbers, and how their consistency can be finally verified. After combining all numbers into three diagrams, this paper finally discusses the potential and obstacles for recycling of each of the material flows discussed. For instance, the results show that there is a good potential for recovering minerals from non-fruit biomass, where over half of Mg, Ca and S end up, at 58%, 70% and 70% respectively. However, its being virtually inextricably mixed with plastic is a huge barrier, requiring changes such as biodegradable plastics. Finally, by quantifying the flows per unit of produce (1 kg tomato), this paper provides numbers for dimensioning possible symbiotic production processes, such as aquaculture or animal husbandry.

CONTEXT: For high latitude countries like Norway, one of the biggest challenges associated with greenhouse production is the limited availability of natural light and heat, particularly in winters. This can be addressed by changes in greenhouse design elements including energy saving equipment and supplemental lighting, which, however, also can have a huge impact on investments, economic performance, resources used and environmental consequences of the production.OBJECTIVE: The study aimed at identifying a greenhouse design from a number of feasible designs that generated highest Net Financial Return (NFR) and lowest fossil fuel use for extended seasonal (20th January to 20th November) and year-round tomato production in Norway using different capacities of supplemental light sources as High Pressure Sodium (HPS) and Light Emitting Diodes (LED), heating from fossil fuel and electricity sources and thermal screens by implementing a recently developed model for greenhouse climate, tomato growth and economic performance.METHODS: The model was first validated against indoor climate and tomato yield data from two commercial greenhouses and then applied to predict the NFR and fossil fuel use for four locations: Kise in eastern Norway, M ae re in mid Norway, Orre in southwestern Norway and Tromso in northern Norway. The CO2 emissions for natural gas used for heating the greenhouse and electricity used for lighting were calculated per year, unit fruit yield and per unit of cultivated area. A local sensitivity analysis (LSA) and a global sensitivity analysis (GSA) were performed by simultaneously varying the energy and tomato prices.RESULTS AND CONCLUSIONS: Across designs and locations, the highest NFR for both production cycles was observed in Orre (116.9 NOK m- 2 for extended season and 268.5 NOK m- 2 for year-round production). Fossil fuel was reduced significantly when greenhouse design included a heat pump and when extended season production was replaced by a year-round production.SIGNIFICANCE: The results show that the model is useful in designing greenhouses for improved economic performance and reduced CO2 emissions from fossil fuel use under different climate conditions in high latitude countries. The study aims at contributing to research on greenhouse vegetable production by studying the effects of various designs elements and artificial lighting and is useful for local tomato growers who either plan to build new greenhouses or adapt existing ones and in policy formulation regarding incentivizing certain greenhouse technologies with an environmental consideration or with a focus on increasing local tomato production.

Tomato greenhouses at high latitudes (> 58 degrees North) require supplemental light to enable high yields and year-round production. Supplemental light systems can differ in lamp type, high-pressure sodium (HPS) or light emitting diode (LED), and also vary in lamp capacity. Based on a combined greenhouse climate, tomato yield, and greenhouse economics model, a methodology was developed, for determining the optimal supplemental light system, dependent on local climate and economic conditions. Two optimisation objectives were considered separately, maximal energy use efficiency (EUE) and maximal net financial result (NFR). The developed methodology was applied to four different greenhouse locations in Norway. At each location, both optimisation objectives were reached with LEDs. The optimal lamp capacities range from 256 to 341 mmol m(-2) s(-1) (maximal EUE) and 302-323 mmol m(-2) s(-1) (maximal NFR). The economically optimal lamp capacity is little sensitive to climate conditions. At the lamp type respective NFR maxima, LEDs resulted, on average, in 10% higher tomato yield, 102.2 NOK m(-2) year-1 higher NFR, and 35% higher EUE. Consequently, switching from HPS lamps to LEDs enables increasing productivity, energy efficiency and profitability of greenhouse tomato production. Furthermore, the difference between EUE and NFR optima was, on average, 24% lower in terms of EUE and 56% lower in terms of NFR, when using LEDs instead of HPS lamps. On farm-scale, the proposed methodology can be used as decision-support-tool for selecting an efficient and profitable supplemental light system for greenhouse tomato production, dependent on local climate and economic conditions. (c) 2022 IAgrE. Published by Elsevier Ltd. All rights reserved.