Soilless Culture System Research Articles

Mineral and organic growing media have distinct community structure, stability and functionality in soilless culture systems.

The choice of soilless growing medium for plant nutrition, growth and support is crucial for improving the eco-sustainability of the production in horticultural systems. As our current understanding of the functional microbial communities inhabiting this ecosystem is still limited, we examined the microbial community development of the two most important growing media (organic and mineral) used in open soilless horticultural systems. We aimed to identify factors that influence community composition over time, and to compare the distribution of individual taxa across growing media, and their potential functionality. High throughput sequencing analysis revealed a distinctive and stable microbial community in the organic growing medium. Humidity, pH, nitrate-N, ammonium-N and conductivity were uncovered as the main factors associated with the resident bacterial communities. Ammonium-N was correlated with Rhizobiaceae abundance, while potential competitive interactions among both Methylophilaceae and Actinobacteridae with Rhizobiaceae were suggested. Our results revealed that soilless growing media are unique niches for diverse bacterial communities with temporal functional stability, which may possibly impact the resistance to external forces. These differences in communities can be used to develop strategies to move towards a sustainable horticulture with increased productivity and quality.

EFFECT OF SUBSTRATE MIXTURES AND NUTRIENT SOLUTIONS SOURCES ON STRAWBERRY PLANTS UNDER CLOSED HYDROPONIC SYSTEM

Current study was done for evaluation effect of substrate mixtures and nutrient solutions on growth, yield and chemical characteristics of strawberry (Fragaria×ananassa) cv. Festival in soilless culture system. Planting was done on 1st week of October during the two winter seasons of 2012/2013 and 2013/2014 under unheated double-span plastic house conditions, Central Laboratory for Agricultural Climate (CLAC), Agricultural Research Center (ARC). Experimental treatments consisted of three substrate mixtures perlite: peat moss (1:1v/v) (M1), perlite: vermicompost (4:1v/v) (M2), and perlite: plant compost (4:1v/v) (M3) and three nutrient solutions (vermicompost-tea, animal compost-tea and mineral nutrition (control). The tested factors were arranged in factorial design with three replicates. Measured traits were number of leaves, plant height, leaf chlorophyll reading, leaf area, early and total yield, number of fruits, average number of fruit and N, P, and K percentage content of the fourth leaf. The results show that these vegetative growth parameters, yield and leaf chemical contents responded and positively significantly to using perlite: peat-moss under this investigation. Furthermore, using mineral solution had significant effects on all measured characteristics. While, using perlite: peat-moss combined with mineral had the highest values of all measured. Adding, using perlite: peat-moss combined with vermicompost-tea was affected in plant height and leaf area. These results were reported during the two seasons.

養液栽培で栽培されるベビーリーフ野菜研究のための実験室レベルでの試験施設について

Investigating several environmental factors affecting plant growth implies having sound experimental facilities equipped to test individual factors in lab-scale although applicable later at the industrial scale. Sometimes, detailed information is hardly given in a manuscript that allows for replications by other authors, maybe due to the shortening of pages requested by journal publishers and editors. A system and methodology was developed for qualitative and quantitative analyses of baby leaf vegetables (BLV) raised in floating growing systems (FGS). Lab-scale pilot plants (LSPP) were developed in 2 greenhouses differing in structure and equipment, suitable for different growing seasons in a continental climate. The equipment and technology allowed multiple treatments and replicates for sound statistical design and data analyses. Environmental conditions and cultural techniques were studied in major and minor species (white mustard, Brassica alba L. Boiss; black mustard, Brassica nigra L. Koch; garden cress, Lepidium sativum L.; water cress, Nasturtium officinale R. Br.; rocket salad, Eruca sativa Mill.; perennial wild rocket, Diplotaxis tenuifolia L. DC.; corn salad, Valerianella olitoria L.; baby spinach, Spinacia oleracea L.) to determine best cultivation techniques in a standard soilless culture system (SCS) for BLV, based on FGS. Considering that SCS can improve raw material quality at harvest, and enhance the postharvest shelf-life of many vegetables and herbs, a standardized growing system is required to obtain premium quality raw material in terms of commercial stage, low nitrate content and long shelf-life. Among the SCS used, the FGS are suitable systems to grow leafy vegetables because the plants can grow at high densities, thereby producing high yields, and in a short time. FGS are based on sub-irrigation technology, avoiding over-head irrigation and contact between nutrient solution and edible parts, and result in greater qualitative and quantitative yields than the traditional cultivation techniques, reducing pollution, crop and substrate residues, leading to clean raw material with potential low microbiological load. The FGS is a modern technology that could be exploited more to enhance yield, quality and safety of fresh and fresh-cut BLV. The LSPP installed are providing the basis for expanding the research to other species and agronomic factors.

Response of strawberry cv. Festival grown under vertical soilless culture system

Strawberry is being promoted for year round production due to its highly desirable taste, flavour and health properties, and it is possible through soilless cultivation. A study on production of strawberry cv. Festival under vertical growth system with four tiers on soilless medium in a passively ventilated greenhouse was attempted. Significant differences were observed for the growth parameters, viz., number of leaves, leaf area, crown diameter and biomass production. Of the four tiers, first tier planting tended to show the enhanced plant growth and photosynthesis rate with early flowering, higher fruit yield of improved fruit quality than lower tiers tested.

MICROJARDIM CLONAL DE MIRTILEIRO EM SISTEMAS DE CULTIVO SEM SOLO

RESUMO O uso de microjardins clonais em sistemas de cultivo sem solo para fornecimento de material propagativo na cultura do mirtileiro (Vaccinium spp.) pode trazer grandes avanços na produção de mudas dessa cultura. O objetivo desta pesquisa foi avaliar a produção de microestacas e a sobrevivência de plantas matrizes de mirtileiro micropropagadas das cultivares Woodard e Aliceblue, em dois sistemas de cultivo. Os sistemas de cultivo utilizados foram o semi-hidropônico (floreiras com substrato de areia e fornecimento diário de solução nutritiva) e o com substrato organomineral (sacos plásticos com substrato comercial e fornecimento de solução nutritiva a cada 15 dias). Após o período de 90 dias do plantio das plantas matrizes, foram iniciadas as coletas de microestacas, as quais foram realizadas a cada 60 dias, com exceção do período de inverno, em que as coletas foram realizadas a cada 90 dias, totalizando ao final do experimento onze coletas. O experimento foi constituído como um fatorial 2 x 2 x 11 (sistemas x cultivares x coletas), em delineamento inteiramente casualizado, com três repetições de 12 plantas cada. Foram avaliadas a produção total de microestacas ao final das onze coletas, o número de microestacas produzidas por planta matriz a cada coleta, a sobrevivência das plantas matrizes ao final das onze coletas e a sobrevivência das plantas matrizes a cada coleta. Os resultados indicaram que o sistema semi-hidropônico foi superior ao substrato organomineral para a produção de microestacas de ambas as cultivares. A maior produtividade total de microestacas ocorreu no sistema semi-hidropônico combinado com a cultivar Aliceblue, com produção total média de 237,67 microestacas. Porém, nesta condição, houve menor sobrevivência das plantas matrizes. A produção de microestacas apresentou alternância ao longo das coletas. A sobrevivência das plantas matrizes diminuiu após sucessivas coletas. Após as coletas de verão, ocorreu maior mortalidade de plantas matrizes.

Soilless cultivation of cherry tomato with gutter subirrigationn and reused substrate

Soilless cultivation systems in horticultural production are modern technologies that involve the supply of water and minerals through the nutrient solution and plant growth on media. The soilless cultivation of vegetables ensures higher yields and better quality than with traditional soil crops. When managed in a closed system with irrigation water of good quality soilless cultivation can significantly reduce the environmental impact of nutrient solutions with respect to crops grown in open systems. Compared with drip irrigation, gutter subirrigation simplifies the management of the closed system because disinfection of recirculated nutrient solution and correction of its chemical composition is not necessary. Gutter subirrigation was developed in previous experiments for the cultivation of tomato on fresh substrate. The objective of this work was to evaluate the use of the same substrate after two consecutive crops of tomato and to study the effect of the presence, if any, of previous radical residues with the same cultivar and rootstock. The experiment was conducted in an unheated iron and polycarbonate greenhouse with forced ventilation. Cherry tomato plants were transplanted into pots containing fresh or reused coconut fiber. The following parameters were considered: biomass, production, product quality (electrical conductivity, pH, titratable acidity, dry residue, dissolved solid content) and chemical analysis of recirculated and radical nutrient solution. The results obtained in this experiment reveal no significant differences in production and fruit quality between plants grown on fresh substrate and those grown on reused substrate (marketable yield was 5.4 kg m-2 vs 5.3 kg m-2, respectively).

New ‘solutions’ for floating cultivation system of ready-to-eat salad: A review

Soilless cultivation systems represent an alternative to traditional agriculture, as they offer the possibility to reduce water use and to design nutrient formulations of the hydroponic solutions in order to maximize yield and quality of the products. Reduction in accumulation of undesired compounds, like e.g. nitrate, and enhanced nutritional value for human consumption, like e.g. Se-rich compounds, could be reasonably achieved. These aspects, together with the extension of the shelf life, would increase the market value of ready-to-cut vegetables. This review discusses how recent advances in understanding the role of plant nutrients and their interactions and the management of nutrient solution composition, including the addition of non-essential elements, micronutrients’ biofortification, biostimulants, together with the control of some crucial environmental conditions, like temperature, can help accomplishing this task.

NITROGEN AND AERATION LEVELS OF THE NUTRIENT SOLUTION IN SOILLESS CULTIVATION SYSTEMS AS IMPORTANT GROWING CONDITIONS AFFECTING INHERENT QUALITY OF BABY LEAF VEGETABLES: A REVIEW

NITROGEN AND AERATION LEVELS OF THE NUTRIENT SOLUTION IN SOILLESS CULTIVATION SYSTEMS AS IMPORTANT GROWING CONDITIONS AFFECTING INHERENT QUALITY OF BABY LEAF VEGETABLES: A REVIEW

Amelioration of an open soilless cultivation system for microgardening spinach (Spinacia oleracea L.)

The objective of this study was to develop an open soilless culture system with high water and nutrient use efficiency, and low emission in the environs for microgardening high quality spinach. For this purpose, spinach (Spinacia oleracea L.) was grown in containers with soilless media supplemented with organic and inorganic nutritional sources. The experiment was laid out in a complete randomized design with four replications. Seven growing media were assessed: peat moss, peat moss combined with 150, 200 and 250 ppm ammonium nitrate (NH 4 NO 3 ), and peat moss amended with compost having nitrogen equivalent to the mentioned NH 4 NO 3 concentrations. Scheduled and quantified irrigation was provided with a sprinkler system to conserve water and minimize emission into the environment. Salt accumulation and pH of media was monitored throughout growing period. Spinach leaves were analyzed for total soluble solids, titratable acidity, ripening index, total nitrogen, total organic carbon, carbon to nitrogen ratio, fresh biomass, dry biomass, dry matter (mg g -1 fresh biomass), leaf moisture contents, nitrate content, colorimetric traits (lightness, chromacity and hue angle), ascorbic acid, total flavonols and anthocyanins and antioxidant capacity. Among all media, combinations of peat moss with NH 4 NO 3 resulted in less nitrate, more organic carbon and dry matter (mg g -1 fresh biomass), higher total soluble solid contents and ripening index of the plants. A higher flavonoid content and higher antioxidant capacity were also observed in plants grown in these combinations. Further, these media accumulated less salt and maintained optimum pH level for spinach growth.

EFFECTS OF NUTRITIONAL ELEMENTS LEVEL ON NUTRITIONAL CHARACTERS AND PHYTOCHEMISTRY OF STRAWBERRY IN HYDROCULTURE

This study was conducted to evaluate the impacts of nutrient elements on phytochemistry characters and qualities of strawberry in soilless culture system. The experiment was carried out in a factorial experiment based on randomized complete design with three replications. Treatments consisted of 6 groups of strawberry growing on soilless medium made of perlite and coco peat that were treated with different ratio of nutrient solutions. According to the results modified nutrient improved fruit nutritional characters but it was not unique. TSSS, TA, vitamin C and pH often were increased by increasing nutritional elements but anthocyanin was decreased by increasing some nutritional elements.

Microbial safety and sanitary quality of strawberry primary production in Belgium: risk factors for Salmonella and Shiga toxin-producing Escherichia coli contamination.

Strawberries are an important fruit in Belgium in both production and consumption, but little information is available about the presence of Salmonella and Shiga toxin-producing Escherichia coli (STEC) in these berries, the risk factors in agricultural production, and possible specific mitigation options. In 2012, a survey was undertaken of three soil and three soilless cultivation systems in Belgium. No Salmonella spp. were isolated. No STEC was detected in the strawberry samples (0 of 72), but STEC was detected by PCR in 11 of 78 irrigation water and 2 of 24 substrate samples. Culture isolates were obtained for 2 of 11 PCR-positive irrigation water samples and 2 of 2 substrate samples. Multivariable logistic regression analysis revealed elevated generic E. coli numbers (the odds ratio [OR] for a 1 log increase being 4.6) as the most important risk factor for STEC, together with the berry-picking season (elevated risk in summer). The presence of generic E. coli in the irrigation water (≥1 CFU per 100 ml) was mainly influenced by the type of irrigation water (collected rainfall water stored in ponds was more often contaminated than groundwater pumped from boreholes [OR = 5.8]) and the lack of prior treatment (untreated water versus water subjected to sand filtration prior to use [OR = 19.2]). The follow-up study in 2013 at one of the producer locations indicated cattle to be the most likely source of STEC contamination of the irrigation water.

Rooting Potential of Mini-Cuttings for the Production of Potato Plantlets

The production of mini-tubers under soilless cultivation system increased the availability of pathogen-free seed potatoes. The objective of this study was to evaluate the rooting capability of mini-cuttings of potato clones as a function of the irrigation solution and the physiological age of the mother plant, under soilless cultivation system. Potato mini-cuttings were collected from young and mature plants of the cultivars Asterix and Macaca and the advanced clone SMINIA 793101-3. The young plants were newly acclimatized individuals and the mature plants were at the stage of producing mini-tubers. In the first experiment, mini-cuttings originating from summer pruning of mature plants were grown under closed soilless cultivation system irrigated with a nu- trient solution developed for the production of potato mini-tubers and a solution comprised of tap water only. The experiment was conducted in a 3 × 2 factorial arrangement (clones and irrigation solutions) in the complete random design with four replicates of 15 mini-cuttings. In the second experiment, the young and mature mini-cuttings were established under a closed soilless cultivation system irrigated with nutrient solution. The experiment was conducted in a 3 × 2 factorial arrangement (clones and physiological age of the mother plant) in the complete random design with four replicates of 15 mini-cuttings. In both experiments, the percentage of rooting and survival of mini-cuttings, number of roots and length of the longest root were assessed at 21 days of cultivation. Potato mini-cuttings can be rooted under closed soilless cultivation system irrigated with nutrient solution or tap water. Mini-cuttings of young plants have higher rooting capability compared to the ones taken from mature plants. The loss of rooting capability depends upon the potato cultivar.

Roofs of the Future: Rooftop Greenhouses to Improve Buildings Metabolism

Ancient civilizations had agriculture production in their metropolis but modern urban planning separated agriculture from cities, such as Chandigarh by Le Corbusier. At present, FAO estimates that urban agriculture produces food for a quarter of world's population, reducing food transport, package and waste impact among others and improving food safety. Meanwhile, city governments and citizens are reinventing their roofs usage in order to take more advantage of them. Rooftop Greenhouses (RTGs) are an interesting option because they increase the scarce green area of the cities, create new agricultural spaces and promote food self-sufficiency in urban areas among other growing interests. RTGs are greenhouses located on the roof of the buildings that usually produce food using soil-less culture systems. These structures as well as the green façades called Vertical Farming (VF) are part of the “building-based Urban Agriculture (UA)”.In this sense, this article presents the first results of the research project Fertilecity, which aims to analyze, from a technological and sustainability approach, a new agricultural production system for Mediterranean urban areas through the integration of greenhouses on the roof of buildings. This innovative system is an integrated RTG (i-RTG) that includes energy, water and CO2 flows in the metabolism of the building. Multidisciplinary experts participate in Fertilecity Project using multiple methods such as Life Cycle Assessment and the Integrated Value Model for Sustainable Assessment (MIVES). Their first results are: a review of the main experiences in UA; an environmental and economic life cycle analysis of implementing Rooftop Greenhouses (RTGs) in Barcelona and the construction of the ICTA Rooftop Greenhouse Lab (RTG-Lab) near Barcelona. This project aims to demonstrate the potential of i-RTGs and quantify their environmental, economic and social benefits, as well as study how they can change the image of our cities.

Soilless Culture System to Support Water Use Efficiency and Product Quality: A Review

The driving force of future agricultural industry is to provide sufficient yield that satisfy the needs of consumers and meet their interests in terms of quality. Soilless cultivation is intensively used in protected agriculture to improve control over the growing environment and to avoid uncertainties in the water and nutrient status of the soil. Recently the type of soilless culture transformed from open to close-loop system. This system is known for better result in water use efficiency, while maintaining the quality of the yield. This study aims to describe the specific purpose of soilless culture specifically in close-loop system and how substrate nutrition produces the better quality of the yields.

Photochemical Wastewater Treatment for Potential Agricultural Use

The urban wastewaters after advanced primary treatment (APT) are again discharged into the river without any use. In the present research in a soilless culture system where maize seedlings were tested three different treatments were planted: 1. Obtained from the effluent water of an APT, 2. Photochemically treated wastewater (PCT) and 3. Urban water network (UW). A block randomly distributed design was tested, with five repetitions where the experimental unit was formed by a 36 cavities filled with Peat Moss and the useful plot was considered by 16 central plants for each experimental unit. Irrigations were scheduled since the first time of the planting, employed 27 mL/cavity. The removal of the organic contaminants present into the water was conducted by the employment of a Batch photoreactor, adapted with a recirculation system (UV/H 2 O 2 /O 3 ), evaluated to determine UV-Vis spectra, pH, color and turbidity parameters initial and final samples. Measurements of height and percentage of germination in plants, where is determined that the seedlings irrigated with water PCT were reached the highest average compared to APT and UW irrigated; After the 50 cm growing plant, a determination of the presence of heavy metal, via atomic absorption method, were carried on analyzing the leaves, roots and stalks of the samples. Concluding that the presences of heavy metals into the APT were higher than PCT treatments, it can be an impediment for the normal growing of the plants. Therefore, the application of the photochemical treatment using (UV/H 2 O 2 /O 3 ) system, represent a viable alternative for the wastewater treatment after the APT process to possible use of irrigation.

New technique for rose production in soilless culture system and disease reduction

ABSTRACTRose flower is one of the most important cut flowers, with the world's highest production rate. Soilless culture has been increasingly popular in plant production worldwide in the past few decades. In two separate trials, the efficacy of Trichoderma harzianum, Anearobacillus migululanas, slow filtration, and UV ultraviolet (UV) treatment and sand filtration in eliminating Fusarium oxyporum, artificially added in the recirculating nutrient solution, was evaluated with Rosea hybrid plants grown in closed soilless systems. The dynamics of these fungi in the recirculating nutrient solution and in the sand filter was also investigated. T. harzianum, A. migululanas, UV treatment and slow sand filtration were effective in reducing Fusarium root rot. However, slow sand filtration may be a more feasible disinfection method than UV because of lower costs of installation and maintenance and for its adaptability to a wide range of production systems. Moreover, these disinfection techniques can be successfully combined with the application of antagonistic microorganisms.

Tomato and eggplant scions influence the effect of rootstock under Na2SO4 salinity

A short-term experiment was conducted to investigate whether the effect of rootstock on plant response to salinity depends on the solanaceous species used as scion. Tomato cv. ‘Ikram’ and eggplant cv. ‘Black Bell’ were grafted onto two tomato interspecific hybrids (‘Beaufort’ and ‘He-Man’). Plants were grown in an open soilless cultivation system and supplied with two nutrient solutions: non-saline control and a saline solution (adding 15 mM Na2SO4, 3.7 dS m−1). Plant dry biomass production and partitioning were influenced by salinity, but its effect was depending on the rootstock/scion combination. ‘Beaufort’ eliminated the deleterious effect of salinity when tomato was used as scion, but reduced (−29.6%) the shoot biomass of eggplant. ‘He-Man’ had a different effect on scion growth under saline conditions: shoot biomass was less reduced in eggplant (−20.6%) than in tomato (−26.8%). Under salt stress, ‘Beaufort’ reduced the accumulation of Na+ in tomato leaves more than in eggplant, whereas no differences were observed between tomato and eggplant grafted onto ‘He-Man’. Stem Na+ accumulation followed a different pattern. The increase of Na+ in the stems was similar for tomato and eggplant grafted onto ‘Beaufort’, whereas stems of tomato accumulated more Na+ compared to eggplant grafted onto ‘He-Man’. The opposite response of the tested rootstocks to salt stress when the scion was either tomato or eggplant seems to be partially related to the capacity of the rootstock and scion to exclude Na+ from the shoot. However, the results of nutrient accumulation within plant tissues imply that other mechanisms in addition to ion competition are involved in the salt resistance of grafted plants.

Sustainable Urban Horticulture of Sweet Pepper via Vermicomposting in Summer Season

The need for extend the urban horticulture to cover the food security demands, to mitigate CO2 emissions and avoid the extreme heat waves drive this study to investigate the ability of using soilless culture systems, vermicomposting technology and net cover in producing vegetables in urban area in summer season. The aim of this study was to determine the effect of different vermicompost rates mixed with the standard substrate peat moss: perlite (perlite: peat moss: vermicompost (45:45:10) (Mix.10%), perlite: peat moss: vermicompost (40:40:20) (Mix.20%), perlite: peat moss: vermicompost (35:35:30) (Mix.30%) and perlite: peat moss (50:50 V/V) (Control) under three microclimate conditions (plants covered with black net, white net and without cover) on vegetative growth and yield of sweet pepper (Capsicum annuum L. cv. Reda) grown in pots culture during summer seasons of 2012 and 2013 at the Central Laboratory for Agricultural Climate, Agricultural Research Center, Dokki, Giza Governorate.
 Physical and chemical properties of substrates, vegetative growth and yield characteristics, agrometerological data and mineral contents were determined. The obtained data indicated that vermicomposting could contribute in mitigate CO2 emission, save the essential nutrients and energy via recycling the urban organic wastes to vermicompost. The physical and chemical properties were affected by vermicompost. The best vegetative growth and yield of sweet pepper were given by (Mix.20%) vermicompost mixture followed by (Mix.10%) and (Mix.30%) vermicompost mixture. There were also significant differences between cover net treatments in affecting vegetative growth and yield of pepper, the white net was superior for producing pepper during the summer season; while the black net gave the lowest plant growth and yield. The best treatment was (Mix.20%) vermicompost mixture with white net cover, while the lowest vegetative growth and yield were obtained by (Control) vermicompost mixture with black cover net during the two tested seasons. These results suggested that vermicomposting and green roof can be used in urban area for producing food instead of incineration the urban organic wastes or imported food from rural area and using white cover net to improve the pepper growth and productivity during summer season.

Effects of Nutrient and NaCl Salinity on Growth, Yield, Quality and Composition of Pepper Grown in Soilless Closed System

The effects of nutrient or sodium chloride (NaCl) salinity on pepper grown in closed soilless culture systems were studied. A control (2 dS m−1) and two saline nutrient solutions (4 dS m−1) differing in the salt sources (fertilizers or NaCl) were studied. Shoot biomass production as well as total and marketable yield were more affected by NaCl than nutrient salinity. Fruit dry matter and total soluble solids increased in both salinity treatments compared to the control. Total phenol content rose slightly (10%) with NaCl salinity, while the concentration of carotenoids was enhanced by 40% with NaCl compared to the control and nutrient salinity. The results showed that the response of pepper to salinity is both osmotic and ion specific, but a more negative effect was recorded under NaCl stress. Moreover, the highest content of antioxidant compounds in NaCl treated fruits may indicate that NaCl caused more stressful conditions than nutrient salinity.

CLOSING THE WATER AND NUTRIENT CYCLES IN SOILLESS CULTIVATION SYSTEMS

Soilless cultivation systems are common in Dutch greenhouse horticulture, i.e., less than 20% of the greenhouse area is still soil grown. For long, it was assumed that in these so-called closed systems the emission of nutrients and plant protection products (PPPs) was close to zero. However, Water Boards have shown that in greenhouse areas with soilless cultivations the quality of surface waters is often far below the standards for chemical and ecological good water, as is demanded by the Water Framework Directive 2000/60/EC. In 2008 this lead to an agreement between the Grower’s organisation, Water Boards and others to reduce the emission of nutrients and PPPs from these systems to almost zero in 2027. To reach this goal, the sources should be clarified, and solutions should be developed to stop these emissions. We analysed the emission problem by joint fact finding with growers and other stakeholders. Since soilless cultivation systems recirculate nutrient solutions, they have the potency of a closed water cycle, and thus a zero emission of nutrients and PPPs to the water. In reality, drain water is often easily discarded when there is only the slightest doubt about the water quality. On average 10% of the nutrient solution is discharged yearly. From this follows that soilless cultivation in the Netherlands uses 6.5 million m3 year-1 fresh water, and annually emits 1,300 ton N, 200 ton P, and 1,134 kg PPPs. There are large differences in amount discarded between crops and greenhouses: from less than 50 to more than 3000 m3 ha-1 year-1. Reasons for discharge are accumulation of sodium, fear of unknown growth inhibiting factors, imbalances in nutrient composition, and fear of spreading diseases. There can also be significant discharge from filter back-flush water and technical malfunctions. This analysis resulted in a dual approach in our research program. Our long term goal is to close the water and nutrient cycle by developing solutions for the reasons for discharge. We have been focussing on growth inhibition and nutrient imbalances. Calculations show that elimination of those reasons for discharge will reduce the use of fresh water by 2.6 million m3 year-1, and reduce the water pollution by nutrients and PPPs by 60%. This can be further improved to (almost) 100% by the already known, but not yet broadly implemented solutions to prevent discharge (i.e., low sodium supply water, adequate disinfection equipment, and the reuse of filter back-flush water). Our second research goal is to develop end-of-pipe solutions through evaluating water purification tech¬niques for use in a greenhouse environment. These techniques may offer a short term solution to meet the demands of the WFD, but may also be of value on the long term, since growers will want to retain the possibility to discharge occasionally.