Greenhouse Tomato Cultivation Research Articles

Characteristics and Driving Factors of Nitrogen-Use Efficiency in Chinese Greenhouse Tomato Cultivation

Excessive nitrogen fertilizer application in greenhouses could cause a significant variation in the nitrogen-use efficiency at the regional scale. This study aims to quantify agronomic nitrogen-use efficiency (AEN) and identify its driving factors across Chinese greenhouse tomato cultivation. Three hundred and forty-eight AEN values were obtained from 64 papers, including mineral nitrogen (MN) and mineral combined with organic nitrogen (MON) treatments. The average AEN values for the MN and MON treatments were 56.6 ± 7.0 kg kg−1 and 34.6 ± 3.5 kg kg−1, respectively. The AEN of the MN treatment was higher than that of the MON treatment for cultivation using soil with an organic matter content of less than 10 g kg−1 and the drip fertigation method. The AENs of the MN and MON treatments were divided into two segments according to the nitrogen application rate. The inflection points of the nitrogen application rate were 290 and 1100 kg N ha−1 for the MN and MON treatments, respectively. When the ratio of organic nitrogen to total nitrogen was less than 0.4, it was beneficial for improving the AEN. The soil organic matter content and the nitrogen application rate were the most critical factors determining the AEN. These results suggest that rationally reducing the nitrogen input and partially substituting mineral nitrogen with organic nitrogen can help improve the nitrogen-use efficiency.

Evaluating tomato production in open-field and high-tech greenhouse systems

High-tech greenhouse production of vegetables has been proposed as a path to sustainable intensification of food production. While these systems have clear productivity advantages, there are outstanding questions around their overall sustainability that merit evaluation. Using a simulation approach, we assessed crop yields, water, energy, and greenhouse gas footprints, average cost per unit of tomato produced, and net income for Washington State, United States as a case study. Compared to open-field production, high-tech greenhouse resulted in 6.4 times yield per unit area with 231 times energy, 18 times greenhouse gas, and 0.74 times water footprints (per unit of fresh tomato mass). Greenhouse tomato cultivation would need to focus on both reducing the energy needs and shifting to cleaner sources to reduce environmental impacts and lead to sustainable intensification of food production.

Lifecycle Assessment of Tomato Production in Open Field and Greenhouse in Dharmapuri District of Tamilnadu

Aim: Tomatoes are commercially cultivated in open- field (OF) and greenhouse (GH) in Dharmapuri district of Tamilnadu. The main aim of this study is to assess the environmental impact of selected categories in open-field and greenhouse tomato cultivation using the lifecycle assessment (LCA) methodology.
 Methodology: The primary data was gathered from 30 open field and 30 greenhouse farmers in Dharmapuri district. The system boundary selected for the study is ‘cradle to farm gate’ approach and the functional unit based on mass is one ton of tomato production. The Openlca software was used for the impact assessment in which the CML- IA baseline method was used to calculate the impact categories.
 Findings: The results indicated that the environmental impact of greenhouse is lower than the open-field due to high yield and less energy inputs. Field emissions of ammonia, methane, nitrous oxide and carbon dioxide due to the incorporation of large amount of manure and the usage of fertilizers were the main contributor of the impact categories.

Reliability Analysis of Rainwater Harvesting Tanks for Irrigation Use in Greenhouse Agriculture

Rainwater harvesting is an ancient water management practice that has been used to cover potable and non-potable water needs. In recent years, this practice is adopted as a promising alternative and sustainable source of water to meet irrigation needs in agriculture in arid and semi-arid regions. In the present study, a daily water balance model was applied to investigate the size of rainwater tanks for irrigation use in greenhouse begonia and tomato cultivation in two regions of Greece with significant greenhouse areas. For the application of the water balance model, daily rainfall depth values of a 12-year time series (2008–2020) from representative rainfall stations of the study areas were used, as well as the daily water needs of the crops. The greenhouse roof was assumed to be the water collection area of the rainwater harvesting system with values ranging from 1000 to 10,000 m2. The analysis of the results showed that in the case of the begonia crop, the covered tanks ranged from 100 to 200 m3 per 1000 m2 greenhouse area with a reliability coefficient that ranged from 65 to 72%, respectively, to meet the water needs of plants. Further increase of the reliability coefficient was carried out with disproportionately large volumes of tanks. In the case of the tomato crop, covered tank volumes ranged from 100 to 290 m3 per 1000 m2 of greenhouse area, and had a reliability coefficient of 90% to 100%, respectively, while uncovered tanks had a maximum reliability coefficient of 91% for a critical tank volume of 177 m3 per 1000 m2 of greenhouse area and decreased for any further increase of tank volume.

Combined effect of partial root drying and elevated atmospheric CO2 on the physiology and fruit quality of two genotypes of tomato plants with contrasting endogenous ABA levels

Elevated CO2 concentration (e[CO2]) could induce the decline of nutrient concentration in tomato fruit, although it enhances the yield. Alternate partial root drying (PRD) irrigation is a water-saving irrigation strategy, which may enhance tomato fruit quality including both organic and inorganic attributes. Yet, it remains unknown whether PRD could alleviate the negative impact of e[CO2] on the quality attributes of tomato fruit. To investigate that, two genotypes of tomato plants differing in their endogenous abscisic acid level, i.e. Ailsa Craig (wild type, WT) and its correspondent ABA-deficient mutant (flacca), were grown in ambient CO2 (a[CO2], 400 ppm) and e[CO2] (800 ppm) environment, respectively. And three irrigation regimes including full irrigation (FI), deficit irrigation (DI) and PRD were applied during anthesis to fruit ripping stages. The results showed that e[CO2] increased net photosynthetic rate, decreased stomatal conductance and transpiration rate. Tomato yield was more sensitive to irrigation regimes than [CO2], and the reduction of fruit yield caused by PRD was attenuated under e[CO2], especially in flacca. Both e[CO2] and PRD enhanced water use efficiency. The concentration of total soluble solid, total sugar and total acid, as well as fruit firmness were improved in PRD. A negative effect of e[CO2] on fruit mineral nutrition was seen only in flacca, and as expected, such impact was attenuated by the reduced irrigation regimes (DI and PRD). Collectively, it is suggested that the responses of tomato fruit quality to e[CO2] and reduced irrigation regimes are genotypic-dependent, where the endogenous ABA level of the plants plays an important role, and this must be considered in climate management in greenhouse tomato cultivation.

Effects of Combined Biochar and Vermicompost Solution on Leachate Characterization and Nitrogen Balance from a Greenhouse Tomato (Solanum Lycopersicum) Cultivation Soil

ABSTRACT Both biochar (B) and vermicompost (V) can provide the soil with soluble organic matter. We evaluated the effect of B in reducing nitrate and dissolved organic carbon (DOC) losses from soil via leaching together with the effect of B combined with V solution (vermiwash) in increasing the efficiency of plant nitrogen. Tomato plants (Solanum lycopersicum L.) were cultivated in a greenhouse with soil under three different amendments (B, V and a mix BV). B was applied at a rate of 2% w/w corresponding to 34 t ha−1. V was applied at 25 mg per plant through fertigation. Leachate and soil were monitored in terms of nitrates and DOC throughout the trial (120 days), and plants and fruits were monitored in terms of nitrogen balance index (NBI) and dry matter biomass. B and BV significantly decreased NO3 –_N content in the leachate in all recovered times by 66.8% and 71.3%, respectively. In contrast, the absence of biochar in the V treatment led to a 38.1% increase in NO3 –_N concentration. Similar results were found for DOC content. The dry biomass of plants increased in B and BV treatments by 19.5 and 28.7%, respectively. The dry biomass of tomato fruits was enhanced by 18.5, 12.1, and 37% in V, B and BV treatments, respectively. Synergisms were found between the char material and complex organic compounds derived from the vermicompost process in terms of safeguarding the quality of the soil, the underground water, and the sustainability of crops.

Effect of leaf-area management on tomato plant growth in greenhouses

Photosynthesis in plants depends on various vegetative growth factors, such as leaf age, leaf area, and leaf number. Leaf area is related to canopy photosynthesis and production of crops. However, there are few studies that quantify the relationship between leaf area and crop growth according to various climatic conditions for tomato crops. Therefore, this study was conducted to quantify the relationship between leaf area and two cultivars of tomato plants in a greenhouse in the northeast Asian climate. In the experiment, tomato seedlings of ‘Super334’ and ‘Poongyoung’ were used. We ran the experiment from May 28 to September 16, 2019, with various leaf-area index (LAI) treatments. The greenhouse environments were managed to maintain a relative humidity of 38–90% and temperature of 15–35 °C. Irrigation was controlled based on accumulated radiation. We compared the tomato growth according to five leaf-area treatments: non-defoliation (control), LAI (2.5), LAI (3.0), LAI (3.5), and LAI (4.0). In terms of the vegetative growth of tomatoes, the smaller the LAI, the greater the plant height of the crops. In terms of reproductive growth, the number of flowers did not show significant differences between the control and the LAI treatments, but the number of fruits in the ‘Poongyoung’ cultivar seemed to increase with the higher LAI treatment. In terms of fruit quality, although fruit weight, sugar content, and acidity did not show any trends between the treatments, firmness was reduced below 3.0 LAI treatments. Given this experiment, we think that appropriate leaf-area management may be effective for increasing productivity in greenhouse tomato cultivation and that the data on the relationship between leaf area and plant growth of the various tomato cultivars should be further increased by continuous research.

Early recognition of tomato gray leaf spot disease based on MobileNetv2-YOLOv3 model

BackgroundTomato gray leaf spot is a worldwide disease, especially in warm and humid areas. The continuous expansion of greenhouse tomato cultivation area and the frequent introduction of foreign varieties in recent years have increased the severity of the epidemic hazards of this disease in some tomato planting bases annually. This disease is a newly developed one. Thus, farmers generally lack prevention and control experience and measures in production; the disease is often misdiagnosed or not prevented and controlled timely; this condition results in tomato production reduction or crop failure, which causes severe economic losses to farmers. Therefore, tomato gray leaf spot disease should be identified in the early stage, which will be important in avoiding or reducing the economic loss caused by the disease. The advent of the era of big data has facilitated the use of machine learning method in disease identification. Therefore, deep learning method is proposed to realise the early recognition of tomato gray leaf spot. Tomato growers need to develop the app of image detection mobile terminal of tomato gray leaf spot disease to realise real-time detection of this disease.ResultsThis study proposes an early recognition method of tomato leaf spot based on MobileNetv2-YOLOv3 model to achieve a good balance between the accuracy and real-time detection of tomato gray leaf spot. This method improves the accuracy of the regression box of tomato gray leaf spot recognition by introducing the GIoU bounding box regression loss function. A MobileNetv2-YOLOv3 lightweight network model, which uses MobileNetv2 as the backbone network of the model, is proposed to facilitate the migration to the mobile terminal. The pre-training method combining mixup training and transfer learning is used to improve the generalisation ability of the model. The images captured under four different conditions are statistically analysed. The recognition effect of the models is evaluated by the F1 score and the AP value, and the experiment is compared with Faster-RCNN and SSD models. Experimental results show that the recognition effect of the proposed model is significantly improved. In the test dataset of images captured under the background of sufficient light without leaf shelter, the F1 score and AP value are 94.13% and 92.53%, and the average IOU value is 89.92%. In all the test sets, the F1 score and AP value are 93.24% and 91.32%, and the average IOU value is 86.98%. The object detection speed can reach 246 frames/s on GPU, the extrapolation speed for a single 416 × 416 picture is 16.9 ms, the detection speed on CPU can reach 22 frames/s, the extrapolation speed is 80.9 ms and the memory occupied by the model is 28 MB.ConclusionsThe proposed recognition method has the advantages of low memory consumption, high recognition accuracy and fast recognition speed. This method is a new solution for the early prediction of tomato leaf spot and a new idea for the intelligent diagnosis of tomato leaf spot.

Treated Wastewater and Fertigation Applied for Greenhouse Tomato Cultivation Grown in Municipal Solid Waste Compost and Soil Mixtures

Low-fertility soil and the use of brackish water for irrigation act as obstacles and limit crop production. The utilization of municipal solid waste (MSW), compost (C), and treated wastewater (TWW) is receiving attention nowadays not only to overcome the above limitations but also as an efficient way for waste management and reuse of raw materials. In the present study, MSW compost in different ratios (5%, 10%, 20%, and 40%), fertigation and/or irrigation with TWW were studied in tomato plants (Solanum lycopersicum L.). The addition of compost increased organic content, pH, electrical conductivity (EC), and mineral content of the growing media, while fertigation and TWW supported the mineral status of the growing media, and this was reflected in the increase of N, K, and Na in tomato leaves. Plants grown in compost-based media with fertigation produced more leaves, compared to the control, while irrigation with TWW did not increase the number of leaves. Plant biomass increased with the application of ≥20% C, fertigation, and/or TWW applications. Plant yield increased in 40% C, while fertigation increased yield in case of lower (5%-10% C) compost ratios, but TWW application did not change the yield. The combination of high C ratios and fertigation and/or TWW decreased tomato fresh weight. Different levels of C did not affect leaf photosynthesis, stomatal conductance, internal CO2 concentration, and chlorophyll fluorescence, but, in general, the combination of compost with fertigation and/or TWW affected them negatively. Fruit total soluble solids, acidity, ascorbic acid, firmness, and total phenolics were increased with the high ratios of compost and/or fertigation and TWW applications, but marketability did not. Bacteria (total coliform and Escherichia coli) units increased in growing media subjected to TWW, but lower levels were counted on the fruit, mainly due to splashing or fruit contact with the soil. The results indicate that up to 40% C can be added into the substrate, as increased plant growth and maintained plant yield for greenhouse tomato cultivation is observed, while fertigation and TWW could be used in a controlled manner as alternative means for nutrient and irrigation in vegetables following safety aspects.

Development of a transpiration model for precise irrigation control in tomato cultivation

Since transpiration model of tomato is a main index for precise irrigation control in greenhouse soilless culture, more precise transpiration model needs to be developed for tomato cultivation. Although various models have been developed, they are limited under low VPD condition due to high light intensity in greenhouse, especially during the daytime at summer season of Korea. Therefore, the objective of this study was to develop an improved model considering the above unusual environment in greenhouse. Experiments were conducted between 2017 and 2018. The actual transpiration rate was measured by a load cell, weight measuring device, and used as data for model development. In 2018 experiment, an environment suitable for the growth of crops was established through shading film and humidification. The model equation was developed by calibrating parameters within the VPD range suitable for crop growth with compensated radiation under high light conditions. Experimental results showed that the transpiration rate had exponential increase to the maximum with respect to radiation and transpiration rate to VPD was fitted to gaussian peak shape. The developed model equation was verified by comparing with measured transpiration rate. Verification result showed that the developed model had a higher correlation coefficient than the existing one. In summary, a tomato transpiration model considering the specific environment in the greenhouse was developed in this study. It could be used to precision irrigation and environment control in greenhouse tomato cultivation.

Seaweed Extract Improved Yields, Leaf Photosynthesis, Ripening Time, and Net Returns of Tomato (Solanum lycopersicum Mill.).

Overuse of chemical fertilizers in the intensive greenhouse tomato cultivation system has limited the increase of plant production. Nowadays, seaweed extract has been gradually applied in agriculture as an effective way to achieve a higher yield of crops, but its effects on tomato cultivation have not been fully explored. In this study, a greenhouse experiment was conducted in Shandong province of China with a novel seaweed extract (SES) originated from Sargassum horneri, to investigate the effects of different doses of SES (0, 30, 60, and 90 kg hm–2) on yields, quality, ripening time, and net returns of tomato. The results indicated that the application of SES significantly increased tomato yield by 4.6–6.9% compared to the control, which is attributed to the improved photosynthetic capacity of tomato leaves. The yields of tomato increased first and then decreased with increasing dosage of SES, and SES applied at the dose of 60 kg hm–2 achieved the highest tomato yield. Compared to the control, SES at 60 and 90 kg hm–2 significantly increased the hardness of tomato by 10.2 and 19.8%, respectively, and this can help to reduce losses during transportation and storage. Moreover, SES shortened the ripening time of tomato, and the coincidence between tomato harvest and sale price peak achieved a high net return.

Morphology, yield and quality of greenhouse tomato cultivation with flexible photovoltaic rooftop panels (Almería-Spain)

Flexible photovoltaic panels are an option to generate renewable energy that could be compatible with the production of greenhouse crops, especially in warm sunny countries. The aim of this study was to evaluate, during two growing seasons, the effect of shading caused by flexible photovoltaic panels mounted on the greenhouse roof on tomato plant morphology and fruit yield and quality. This study was conducted during two growing seasons in a commercial greenhouse for tomato production. Two photovoltaic panel arrays placed on the greenhouse roof were analysed. Both occupied 9.8% of the cover. The parameters studied were PAR, plant morphology, crop yield and fruit quality. The results show that the small reduction in PAR caused by flexible photovoltaic panels on the roof did not affect the total and marketable yield; plant morphology; number of flowers per branch; and fruit colour, firmness and pH. However, the fruit diameter decreased, without affecting the yield (kg·m−2). Both flexible photovoltaic panel arrays on the greenhouse roof produced a similar effect on plant morphology, crop yield and fruit quality.

Reduction of sooty mold damage through biocontrol of the greenhouse whitefly Trialeurodes vaporariorum (Hemiptera: Aleyrodidae) using selective insecticides in tomato cultivation greenhouses

The proliferation of sooty mold on tomato fruit, Solanum lycopersicum L.—as caused by the secretion of honeydew on the fruit by greenhouse whitefly, Trialeurodes vaporariorum (Westwood) (Hemiptera: Aleyrodidae)—has recently become a serious problem in estivo-autumnal greenhouse tomato cultivation in Japan. It is becoming increasingly difficult to control T. vaporariorum using insecticides because whiteflies have developed resistance to a variety of insecticides. As the first step towards integrated pest management, we examined whether the use of selective insecticides could prompt a cascade process in which an increase in parasitoids is followed by a decrease in whitefly occurrence and then a reduction in sooty mold damage. We compared greenhouses in which nonselective insecticides effective against T. vaporariorum and its parasitoids were used (hereafter denoted “nonselective insecticide greenhouses”) with greenhouses in which selective insecticides for T. vaporariorum were used (hereafter denoted “selective insecticide greenhouses”) in terms of the density and level of parasitism of T. vaporariorum as well as the degree of damage from sooty mold. The number of parasitized whiteflies increased with the number of whiteflies in the selective insecticide greenhouses, whereas it remained at low levels regardless of the number of whiteflies in the nonselective insecticide greenhouses. Furthermore, the selective insecticide greenhouses showed significantly higher parasitism levels, fewer whiteflies, and reduced sooty mold damage compared to the nonselective insecticide greenhouses. These results suggest that the use of selective insecticides causes an increase in parasitism, which in turn suppresses the number of greenhouse whiteflies and, eventually, sooty mold.

Changes in the abundance and structure of bacterial communities in the greenhouse tomato cultivation system under long-term fertilization treatments

The influence of fertilization on soil microenvironments is one of the frontier topics in agricultural science. Despite the numerous relevant studies on cropland, little is known about the effect of fertilization treatments, especially long-term treatments, on greenhouse vegetable cultivation systems. In this study, the greenhouse tomato (Solanum lycopersicum L.) cultivating soils in Shouguang, Shandong province, China, subjected to different fertilization treatments over a 11-year period were examined. The abundance and structure of the bacterial communities, particularly the pathogenic and beneficial communities, were analyzed. The results revealed that the carbon-nitrogen (C/N) ratio of the fertilizer input played crucial roles in soil fertility improvement. The treatment of “conventional chemical N and straw” with a C/N ratio of 33:1 presented the highest increase in soil nutrition and microbial activities, when compared with the treatments of “conventional chemical N” and “organic amendment only”, indicating the structural rationality of the microbial community. Disproportionate input of nitrogen tended to introduce soil-borne pathogens such as Luteimonas and suppress beneficial microorganisms such as nitrifier. Studies on the below-ground changes of soil could help to develop an optimized microbial community structure and an agro-ecosystem with better sustainability.

Photosynthesis, plant growth, and fruit production of single-truss tomato improves with supplemental lighting provided from underneath or within the inner canopy

Light insufficiency is a major abiotic stress limiting plant growth and crop yield in intensive greenhouse production. The application of supplemental lighting to the lower canopy is an efficient method to increase irradiation levels in greenhouse tomato cultivation systems. We evaluated the effects of supplemental lighting provided from underneath the canopy (USL) or within the inner canopy (ISL) on leaf photosynthetic traits, plant growth, and fruit development in single-truss tomato plants. Both USL and ISL significantly promoted leaf photosynthetic activities, plant growth, and fruit production in plants exposed to low solar irradiation levels. The use of USL maintained relatively stable light irradiation conditions in the lower canopy. It also promoted photosynthesis through improved CO2 assimilation and stomatal conductance, and contributed more to fruit yield than ISL. However, ISL induced greater increase in fruit soluble solid contents because of higher exposure to direct supplemental light to fruit. Based on physiological outputs and an energy cost performance analysis, the application of USL may be more financially viable than the use of ISL.

Carbon footprint and cumulative energy demand of greenhouse and open-field tomato cultivation systems under Southern and Central European climatic conditions

The horticultural industry consumes increasing amounts of energy and water contributing to greenhouse gas emissions and global warming. The aim of this study was to investigate the energy flow and the environmental impact of different tomato cultivation systems when renewable energy sources are implemented in the production chain. Seven scenarios including heated greenhouses and open-field crops, in Southern and Central Europe, were examined in order to identify potentials to reduce energy costs, greenhouse gas emissions and increase water use efficiency along the cultivation phase. The environmental impact category applied in this work (carbon footprint) is related to global warming potential, which includes the basic emitted greenhouse gases contributing to climate change and uses CO2 as reference gas (CO2-equivalents). Additionally, an energy flow indicator (cumulative energy demand) and an inventory flow indicator (water use), both relevant to climate change, agriculture and energy processes were determined to assess the different scenarios. The main results showed that annual carbon footprint values varied between 0.1 and 10.1 CO2-eq/kg tomato. Annual cumulative energy demand presented values from 0.8 to 160.5 MJ/kg tomato. Water use efficiency values ranged between 25.6 and 60.0 L/kg. Hotspots for all seven scenarios were determined, with fossil fuel consumption accounting for most of the environmental impact, where applicable. Open-field tomato cultivation presented lower greenhouse gas emissions and cumulated energy demand, however water use efficiency values were smaller than in greenhouse scenarios. In greenhouse production, the use of renewable energy sources and an increased marketable yield reduced their greenhouse gas emissions drastically, even to the levels of open-field cultivation.

The Possibility of Meeting Greenhouse Energy and CO2 Demands Through Utilisation of Cucumber and Tomato Residues

The article examines the possibility of using residues from greenhouse cucumber and tomato cultivation as biomass for energy and CO2 production in order to meet greenhouse needs. Methane fermentation and combustion were compared. Moreover, the legitimacy of ensiling as a storage method for biogas plant was evaluated. The tested waste was found to be an unsuitable feedstock for the production of silage due to low sugar and high protein content. Fresh waste had a higher biogas yield than silage; however, its fermentation lasted longer. Furthermore, the results showed that, in the case of fresh residues, the methane fermentation proved to be a more energy-efficient process, while air-dry biomass is a more sustainable feedstock for combustion. The energy and CO2 balance showed that, regardless of the method used, the available quantity of waste is too small to meet the greenhouse needs.

Economic Sustainability of Italian Greenhouse Cherry Tomato

Greenhouse tomato cultivation plays an important role in Sicily, being the primary production area in Italy, due to its favorable pedo-climatic conditions that permit extra-seasonal productions. In Sicily, more than half of greenhouse tomato production is derived from the Province of Ragusa on the southeastern coast, where especially cherry tomato typologies are cultivated. Over the last decade, the Ragusa Province has registered a decrease both in terms of greenhouse tomato area and harvested production due to several structural problems that would require restructuring of the tomato supply chain. Thus, since recognition of real costs and profitability of tomato growing is a vital issue, both from the perspective of the farm, as well as from that of the entrepreneur, the aim of this paper was to analyze the economic sustainability of Sicilian greenhouse cherry tomato cultivated in the Ragusa Province. In particular, an economic analysis on 30 representative farms was conducted in order to estimate production costs and profits of greenhouse cherry tomato. According to our results, the lack of commercial organization, which characterizes the small farms we surveyed, determines low contractual power for farmers and, consequently, low profitability.

A DECISION SUPPORT SYSTEM FOR TOMATO GROWERS BASED ON PLANT RESPONSES AND ENERGY CONSUMPTION

ISHS International Symposium on New Technologies for Environment Control, Energy-Saving and Crop Production in Greenhouse and Plant Factory - Greensys 2013 A DECISION SUPPORT SYSTEM FOR TOMATO GROWERS BASED ON PLANT RESPONSES AND ENERGY CONSUMPTION

Soil nitrogen mineralisation dynamics under long-term different irrigation methods in greenhouses

Irrigation is the only source of soil water in greenhouse cultivation. The objective of this study is to illustrate the differences in soil organic nitrogen mineralisation caused by irrigation volume and frequency, and provide theoretical bases for the process of nitrogen transformation and nitrogen fertiliser application under different irrigation methods. The soil nitrogen mineralisation process was studied by the long-term intermittent leaching aerobic incubation method which was used by Standford and Smith in 1972. Parameters of soil nitrogen mineralisation potential (N0), the mineralisation rate constant (k) and half-life period (t1/2) in different soil layers were studied in greenhouse tomato cultivation for seven years, irrigated in three ways: subsurface irrigation (SI), drip irrigation (DI) and furrow irrigation (FI). The results showed that the first-order reaction kinetic model can be used to predict the soil organic nitrogen mineralisation characteristics in a greenhouse. There were five soil layers (0–10, 10–20, 20–30, 30–40 and 40–50 cm) in this study. In 0–20 cm soil layers, the N0 value of DI was highest, then FI, and SI was lowest. Apart from 10 to 20 cm soil layer, the k values of SI and DI were higher than for FI in other soil layers, while the t1/2 value of FI was highest, then DI, and t1/2 of SI was the lowest. The main reasons were that large amounts of water in FI would lead to increased soil bulk density and reduced soil temperature. DI with property ratio of the temperature and moisture was beneficial to organic nitrogen mineralisation. For SI, due to the overall upward movement of water for many years, nitrate accumulated and the pH value decreased in 0–20 cm soil layers. DI could increase the proportion of N0 value to the soil's total nitrogen. Therefore, according to the results of this study, DI gives the best effect on soil fertility, followed by SI and then by FI.