Organic Greenhouse Research Articles

Does an agroecological approach impact the nematode biological and functional diversity in intensive protected production systems?

ABSTRACT Food production systems in protected conditions are probably the most intensive agricultural systems causing biodiversity loss. Experimental sites in different European areas were established to investigate whether an agroecological approach to organic greenhouse production allows preserving or increasing biodiversity. Soil nematode communities were characterized by DNA-metabarcoding, and some biodiversity indices were calculated. A general increase in absolute number of genera indicates that the innovative treatments potentially positively influence biodiversity. A multidimensional analysis revealed that the change in nematode community compositions is caused more by country and sampling year than by the farming system. However, regionally, some shifts in biodiversity are obvious and the impact by a farming practice likely. This study is the first indication that the implementation of some agroecological measures in European protected cropping systems is feasible as at least they did not worsen (nor improve) soil biodiversity.

Responses of Soil Macro-Porosity, Nutrient Concentrations and Stoichiometry Following Conversion of Rice–Wheat Rotation to Organic Greenhouse Vegetable System

Responses of Soil Macro-Porosity, Nutrient Concentrations and Stoichiometry Following Conversion of Rice–Wheat Rotation to Organic Greenhouse Vegetable System

Effects of different nutrient inputs in organic parsley cultivation

ABSTRACT Parsley (Petroselinum crispum Mill.) can play a key role in healthy nutrition for people. This study evaluated the effects of different fertilisers on parsley grown in organic greenhouse conditions in the Samsun province of Turkey. Three organic fertilisers (liquids based on compost, nettles and wood ash) were tested and compared with chemical fertiliser and a control with no fertiliser. The results showed that application of wood ash solution significantly increased EC and concentrations of P and K in the soil, compared with the no fertiliser control. The nettle extract and the compost solution had the most prominent effects on concentrations of nutrients in the parsley leaf tissue. The highest total yields were obtained in the treatments with nettle extract (8.95 kg m−2) and wood ash solution (8.71 kg m−2), which were similar to the yield in the treatment with chemical fertiliser (8.48 kg m−2). The present results suggested that nettle extract and wood ash solution provided effective fertilisers to achieve high yields and quality in organic parsley cultivation. Further studies were recommended to test combinations of nettle extract and wood ash solutions in different proportions for edible leafy species.

The influence of natural preparations on the chemical composition, flesh structure and sensory quality of pepper fruit in organic greenhouse cultivation

The influence of natural preparations on the chemical composition, flesh structure and sensory quality of pepper fruit in organic greenhouse cultivation

Crop rotations in organic greenhouse production – effects of increased crop diversity on the soil microbiome

Crop rotations in organic greenhouse production – effects of increased crop diversity on the soil microbiome

Tomato microbiome under long-term organic and conventional farming.

The compartment niche is the main reason behind the shifts in endophytic bacterial communities. Long-term organic greenhouse exerted limited influence on the variations of endophytic bacterial communities. Organic greenhouse and root had more complex co-occurrence networks than conventional greenhouse and stem, respectively. Cultivable method results found that Protecbacteria, Bacteriodes, and Actinobacteria are the dominant phyla in the endophytes.

Biostimulants Promote Plant Development, Crop Productivity, and Fruit Quality of Protected Strawberries

Berries such as strawberries are recognized as a significant constituent of healthy human diets owing to their bioactive secondary metabolites. To improve crop sustainability, yield and berry quality, alternative production systems should be proposed such as organic farming and the use of biostimulants. Thus, we have compared within a complete randomized block design seven biostimulant treatments: 1-control, 2-seaweed extract, 3-Trichoderma, 4-mycorrhiza, 5-mixture of three bacteria, 6-combination of mycorrhiza + bacteria, and 7-citric acid. Strawberry plants were grown in conventional high tunnel (CH), conventional greenhouse (CG) and organic greenhouse (OG). Our results showed that biostimulants did not impact the soil microbial activity (FDA) when compared with the control. Leaf chlorophyll content and photosynthetic leaf performance were not affected by any studied biostimulants. Bacteria, citric acid, and the combination of mycorrhiza + bacteria increased the number of flowering stalks compared with the control in CH, while bacteria increased the crown diameter and all biostimulants increased fresh and dry shoot plant biomass. Citric acid increased leaf Ca content in CG, when all biostimulants increased leaf N content in CH. Studied biostimulants increased berry productivity in CH, while citric acid treatment had the highest yield in CG. The anthocyanins content increased with the use of biostimulants in CH, whereas Trichoderma (CG) and the combination of mycorrhiza + bacteria (OG) increased the Brix, total polyphenols, and anthocyanin contents of the berries compared with the control.

Conservation Agricultural Practices Impact on Soil Organic Carbon, Soil Aggregation and Greenhouse Gas Emission in a Vertisol

Conservation agriculture (CA), comprising of minimum soil disturbance and crop residue retention (>30%), with a diversified cropping system, has become increasingly popular around the world. It is recognized as a sustainable practice to improve soil health by augmenting key soil properties. However, scanty information exists about the effect of CA practices on soil organic carbon (SOC), aggregation and greenhouse gas emissions (GHG) in a vertisol. Thus, this study investigated the effect of CA practices on SOC, soil aggregation and GHG emission under soybean-wheat and maize-chickpea cropping systems in a vertisol in Central India. Treatment consisted of three different tillage practices, being conventional tillage (CT), reduced tillage (RT), and no tillage (NT) under four cropping systems viz., Soybean–Wheat, Soybean + Pigeon pea (2:1), Maize–Chickpea and Maize + Pigeon pea (1:1). Regardless of cropping system, the soil under NT and RT exhibited better aggregation (20.77 to 25.97% increase), and SOC (12.9 to 19.4% increase) compared to the CT practice in surface layers. The aggregate-associated C concentration increased with aggregate size, and it was highest with large macroaggregates and lowest with silt and clay fractions across different tillage and cropping systems. Higher SOC stock was recorded under NT (4.22 ± 0.133 Mg C/ha) compared to RT (3.84 ± 0.123 Mg C/ha) and CT (3.65 ± 0.04 Mg C/ha) practices at 0 to 5 cm depth. Thus, the adoption of CA practices reduced CO2 emissions, while also contributing to increases in SOC as well as improvement in soil structure.

Soil CO2 Efflux Response to Combined Application of Adaptation Technologies, Nitrogen Fertilization, and External Carbon Amendment in Wheat and Barley Field

Agricultural practices applied to increase crop production and secure future food demands can have a large negative impact on the environmental quality. They should be, therefore, also evaluated in terms of an impact on soil organic carbon (C) content and greenhouse gas emissions. In this study, we investigated the combined effects of adaptation technology (AT) based on no-till crop sowing into cover crop mulch, nitrogen (N) fertilization, and external C supply in the form of biochar, compost, and composted biochar on soil CO2 efflux (Rs). Rs was measured using a closed gas-exchange system in biweekly to monthly intervals during 2 consecutive years when winter wheat (first year) and spring barley (second year) were cultivated. Biochar, compost, and composted biochar had no significant effects on Rs. N fertilization with the medium fertilizer dose tended to increase Rs compared to the control at the beginning of the growing season, followed by Rs decrease later in the season. On the other hand, fertilization with the maximum fertilizer dose mostly decreased Rs throughout the whole growing season. AT affected the dynamics of Rs substantially, depending on the year, site, and N fertilization, resulting in significant interactions between technology and date of measurement and also between site and technology. However, the mean effect of AT across the whole season was insignificant. The results show that the C increase in the soil that occurs after the application of compost and the combination of composted biochar application with AT is not accompanied by an increase in Rs and, thus, leads to at least short-term C storage in the soil. The reduction in CO2 emissions from soil to the atmosphere under AT represents a positive aspect of such management practice for mitigating climate change.

Effect of No-Tillage Management on Soil Organic Matter and Net Greenhouse Gas Fluxes in a Rice-Oilseed Rape Cropping System

No-tillage (NT) management is considered a leading approach for sustaining crop production and improving soil and environmental quality. Based on a long-term no-tillage experiment in a rice–oilseed rape cropping system, we examined differences in soil organic matter (SOM), soil microbial carbon (C) and nitrogen (N) content, and methane (CH4) and carbon dioxide (CO2) fluxes between NT and conventional tillage (CT) management. SOM under NT was 21.0 g kg–1, and a significant difference was detected between 2004 and 2016. SOM increased under NT and CT by averages of 0.60 and 0.32 g kg–1 year–1, respectively. Soil microbial C and N content were higher under CT than under NT. However, soil C:N ratios under NT were 17.4 and 9.7% higher than the CT, respectively, whereas soil microbial C:N ratios under NT were on average 9.47 and 9.70% higher. In addition, about 70% of CO2 net uptake and over 99% of net CH4 emissions occurred during the rice season in May–September in the rice–oilseed rape cropping system. Annual cumulative CH4 and daytime net ecosystem CO2 exchange (NEE) under NT was 1813.9 g CO2 equiv. m–2, 10.8% higher than that under CT. Our results suggest that a higher soil microbial C:N ratio and NEE (CH4 and daytime CO2) could contribute to increasing SOM/C in the surface soil under NT management.

LASAM Model: An Important Tool in the Decision Support System for Policymakers and Farmers

Today’s global food system (including production, transportation, processing, packing, storage, retail sale, consumption, losses and waste) provides income to more than a billion people all over the world and makes up a significant part of many countries’ economies. The 21st century’s food systems that bring food from “farm to fork” face various challenges, including a shortage of agricultural land and water, competition with the energy industry, changes in consumption preferences, a rising global population, negative effects of climate change, etc. Therefore, many countries are working on creating various models to function as an important decision support system tool for policymakers, farmers and other stakeholders. Various agricultural sector models see particularly extensive use in the European Union (EU), determining the impact of the Common Agricultural Policy (CAP) and helping to create future development scenarios. This is why a special model adapted to the national conditions, called LASAM (Latvian Agricultural Sector Analysis Model), was created in Latvia, making it possible to use historical data on the development of agricultural sectors, medium-term price projections for agricultural products in the EU, changes in support policy, as well as the necessity for the resources used to project the long-term (up to 2050) development of agriculture. The LASAM model covers the crop sector, the animal sector and the overall socioeconomic development, as well as the growth of organic farming and greenhouse gas (GHG) emissions. This paper discusses the main objectives achieved in developing a decision support tool and presenting the research results: LASAM was used to prepare projections of the possible development of Latvia’s principal sectors of agriculture until 2050, considering the necessity to reduce GHG emissions, made available through the LASAM web application. Given that the projection data obtained by LASAM are public, they can be used (1) for national policy making in rural business development, which affects the development of the economy as a whole; and (2) internationally, to compare the projections made in Latvia with those obtained through various agricultural sector models and projected development trends.

Liquid Organic Fertilizer Effects on Growth and Biomass of Lettuce Grown in a Soilless Production System

Demand for locally produced, organically grown leafy greens is increasing throughout the United States. However, due to lack of efficient organic fertilizers (OFs) for soilless substrates, organic greenhouse production of leafy greens may be challenging. Therefore, a greenhouse study was conducted to analyze the effects of six liquid OFs on growth and development of lettuce in a soilless system. Two experiments were conducted using a randomized block design, and treatments included six fish- or plant-based OFs: OF1 (5N–1P–1K), OF2 (2N–5P–1K), OF3 (3N–1P–1K), OF4 (2N–2P–2K), OF5 (4N–1P–1K), and OF6 (3N–3P–2K); one inorganic fertilizer treatment (IF, 24N–8P–16K); and one unfertilized control treatment. Fertilizer solutions were prepared at 2 dS⋅m–1 and applied at 100 mL/plant. In Expt. 1, fresh biomass for IF-treated plants was 12% to 38% greater than OF treatments, whereas this difference ranged from 25% to 57% in Expt. 2. Similarly, leaf area values of IF-treated plants were 5% to 40% greater than OF treatments in Expt. 1, and the difference ranged from 28% to 90% in Expt. 2. A possible explanation could be greater availability of nutrients in the IF treatment compared with OF treatments. There was no significant difference among fertilized treatments for number of leaves and stem diameter. Based on the index-based ranking, fish-based (OF1) and fish- and plant-based (OF2 and OF6) performed well among different liquid OFs used in the study. Although the yield under OFs was less compared with that under IF, there is potential to reduce this yield gap by optimized fertility management of these fertilizers. Future research is needed to investigate the impact of optimized rate, timing, different placement, and additional nitrogen (N) sources of OFs on the soilless production of lettuce.

Interactions between nitrogen release from organic fertilisers and organic horticultural soils

Mushroom compost has been one of the most commonly used fertilisers in organic greenhouse vegetable production in Iceland. However, mushroom compost contains conventional chicken manure. Therefore, the use of this fertiliser is prohibited in organic horticulture. In search of alternative nutrient resources, nine different substitutes for mushroom compost (plant compost, four composted animal manures, fishmeal, white clover residues, coarse meal of faba beans, ‘Pioner complete 6-1-3®’) were tested on two soils differing in organic matter in a pot experiment. Dry matter yield (DM) and the apparent N utilisation with the model plant perennial ryegrass was quantified in five cuts throughout 131 days. Both the DM yield and the apparent N utilisation was influenced by the fertiliser, the soil and their interaction. The N release of the tested alternative organic fertiliser resources was described by the N content and C:N ratio of the fertilisers, but was also affected by the soil. It was concluded that the composted animal manures provided an N release equal to mushroom compost and could therefore act as substitutes.

Legume-Based Mobile Green Manure Can Increase Soil Nitrogen Availability and Yield of Organic Greenhouse Tomatoes.

Information about the availability of soil mineral nitrogen (N) in organic greenhouse tomatoes after the application of mobile green manure (MGM), and its impact on plant nutrient status and yield is scarce. Considering this knowledge gap, the effects of legume biomass from faba beans that are cultivated outdoors (FAB), or from feed-grade alfalfa pellets at two different doses (AAL = 330 g m−2; AAH = 660 g m−2) that were applied as MGM on the nutrition and yield of an organic greenhouse crop of tomatoes were evaluated. All of the MGM treatments increased the mineral N concentrations in the soil throughout the cropping period, and the total N concentration in tomato leaves when compared to the untreated control. FAB and AAH treatments had a stronger impact than AAL in all of the measured parameters. In addition, AAL, AAH, and FAB treatments increased the yield compared to the control by 19%, 33%, and 36%, respectively. The application of MGM, either as faba bean fresh biomass or as alfalfa dry pellets, in organic greenhouse tomatoes significantly increased the plant available soil N, improved N nutrition, and enhanced the fruit yield. However, the N mineralization rates after the MGM application were excessive during the initial cropping stages, followed by a marked decrease thereafter. This may impose an N deficiency during the late cropping period.

Legume-Based Mobile Green Manure Can Increase Soil Nitrogen Availability and Yield of Organic Greenhouse Tomatoes

Legume-Based Mobile Green Manure Can Increase Soil Nitrogen Availability and Yield of Organic Greenhouse Tomatoes

Rhizosphere Microbiome Regulates the Growth of Mustard under Organic Greenhouse Cultivation

Organic cultivation can improve soil fertility and biodiversity through the preservation of soil organic matter. Meanwhile, greenhouse cultivation can provide a controlled environment and therefore enables the management of every aspect of plant growth. In recent years, the combination of organic and greenhouse cultivation has slowly become a popular option in tropical regions to prevent the unpredictable impact of weather. Although it is known that organic cultivation significantly increases the density and species of microorganisms, the impact of soil microbiome on short-term vegetable growth under organic greenhouse cultivation is still not elucidated. In this study, we examined soil physiochemical properties as well as the rhizosphere microbiome from healthy and diseased mustard plants under organic greenhouse cultivation. Through next generation sequencing (NGS) analysis, our results revealed that the rhizosphere microbiome structure of healthy mustard plants was significantly different from those of the diseased mustard plants under organic greenhouse cultivation. Our findings suggest that soil microbiome composition can influence the growth of the vegetable significantly. As such, we have shown the impact of soil microbiome on vegetable growth under organic greenhouse cultivation and provide a possible strategy for sustainable agriculture.

Mineral profile of lettuce and onion from organic greenhouse production

Mineral profile of lettuce and onion from organic greenhouse production

Residual Gas for Ethanol Production by Clostridium carboxidivorans in a Dual Impeller Stirred Tank Bioreactor (STBR)

Recycling residual industrial gases and residual biomass as substrates to biofuel production by fermentation is an important alternative to reduce organic wastes and greenhouse gases emission. Clostridium carboxidivorans can metabolize gaseous substrates as CO and CO2 to produce ethanol and higher alcohols through the Wood-Ljungdahl pathway. However, the syngas fermentation is limited by low mass transfer rates. In this work, a syngas fermentation was carried out in serum glass bottles adding different concentrations of Tween® 80 in ATCC® 2713 culture medium to improve gas-liquid mass transfer. We observed a 200% increase in ethanol production by adding 0.15% (v/v) of the surfactant in the culture medium and a 15% increase in biomass production by adding 0.3% (v/v) of the surfactant in the culture medium. The process was reproduced in stirred tank bioreactor with continuous syngas low flow, and a maximum ethanol productivity of 0.050 g/L.h was achieved.

Effects of Different Organic Soil Amendments on Nitrogen Nutrition and Yield of Organic Greenhouse Tomato Crop

Manure is a common source of nitrogen (N) in organic farming. However, manure is not always easily available, while the maximum N amount added as animal manure in organic agriculture is restricted by EU regulations. The present study was designed to test whether green manuring with a warm-season legume and intercropping with a cold-season legume can substitute farm-yard manure or compost as N sources in organic greenhouse tomato crops. To test this hypothesis, a winter-spring (WS) tomato crop was installed in February following the incorporation of crop residues of an autumn-winter (AW) tomato crop intercropped with faba bean, which had been fertilized with cowpea residues as green manure. This treatment, henceforth termed legume treatment (LT), was compared with the use of compost or manure as an N fertilization source in both tomato crops. In addition, a combination of compost and LT was also used as a fourth treatment. The results showed that green manuring with legumes and particularly cowpea can contribute a significant amount of N to the following organic tomato crop, through the biological fixation process. Nevertheless, legumes as green manure, or compost, or their combination cannot efficiently replace farmyard manure as an N fertilization source. Compost exhibited a slow mineralization course.

Compost Functions as Effective Replacement for Peat-Based Potting Media in Organic Greenhouse Transplant Production

Commercial horticulture in many regions of the world depends upon Sphagnum peat as a potting-media substrate, but extracting peat has serious environmental consequences. Composts may be able to serve as effective substitutes for peat and offer potential environmental advantages. The suitability of compost as potting media depends upon the raw materials as well as processing methods used. This study includes two related experiments—one with beet (Beta vulgaris L.) and the other with tomato (Solanum lycopersicum L.)—aimed at assessing the potential viability of farm-produced, food-residuals compost as a replacement for peat-based potting media in the production of organic vegetable transplants. The experiments were conducted in 2021 on the Berea College Farm in Kentucky, USA, a USDA certified organic farm. The results indicated that potting media composed of 75% to 100% compost performed as well as fertilized, peat-based growing media for plant growth. Further, although weeds were present in the compost, weed pressure was not severe enough to adversely affect crop growth. Thus, sterilization of compost, which did eliminate weeds in the compost, was not deemed necessary for using the compost as a partial or complete potting medium. Compost pasteurization was also assessed but was ineffective in destroying weed seeds.