Demonstrator: Experimental facilities (greenhouse and open-field orchard) of INHORT –

Composting with microbial consortia minimising nutrient loses

Type and volume of input materials/products

Use of specific microbial consortia (Streptomyces, Pseudomonas) and different additives (biochar, PGPR strains, the derived bio-organic fertilizers, microbial bioproducts) to accelerate composting and increase nutrient content/ bioavailability

Type & volume of output materials/products

With the use of newly elaborated microbial fertilizers, a circular agricultural production system will be established, in which organic waste biomass is processed to recover plant nutrients and return to the soil to support a sustainable production with minimal polluting emissions, towards a target of zero pollution.

VEGETATION SEASON 2023

MATERIAL AND METHODS

Strawberry plants

A field experiment with strawberry plants cv. Lycia was established in May 2023 at the Experimental Orchard of the National Institute of Horticulture in Skierniewice (IO-PIB). Frigo class A seedlings were used for the experiment establishment. Prior to setting up the experiment, biochar was applied at a rate of 2L/plot (15 plants), mixed with the topsoil layer, and poultry manure (granulate) at a rate of 200 g/plot was also applied. Strawberry plants were planted with a spacing of 0.9 m x 0.2 m.

The following measurements were conducted for the strawberry plants:

– Plant height (cm/plant),

– Chlorophyll content of the leaves (SPAD unit/plant).

Cucumber plants

A field experiment with cucumber plants cv. Octopus was established at the Experimental Orchard of the National Institute of Horticulture in Skierniewice (IO-PIB). Cucumber seeds were sown in May 2023. Prior to setting up the experiment, biochar was applied at a rate of 2L/plot (2 m^2), mixed with the topsoil layer, and Kurzak (granulate) at a rate of 200 g/plot (2 m^2) was also applied. Each plot constituted an experimental unit, where 14 seeds were sown with a spacing of 0.3 m within the row and 1 m between rows.

The following measurements were conducted for the cucumber plants:

– Chlorophyll content of leaves (SPAD unit/plant),

– Number of fruits (pcs/plant),

– Average weight of one fruit (g/plant),

– Total yield (g/plant),

– Assessment of the degree of root colonisation by arbuscular mycorrhizal fungi.

Apple trees

For the field experiment with apple trees, 4-year-old trees cv. Gold Milenium grafted on M9 rootstock, located in the Experimental Orchard of the National Institute of Horticulture in Skierniewice in Dąbrowice (IO-PIB), were selected. In spring 2023, the apple trees were fertilised with poultry manure at a rate 300 g/tree and biochar – 2L/tree. Biochar fertilizer was applied to the soil in a ring around the tree trunk and mixed with the topsoil layer. The trees were planted with a spacing of 2 m x 4 m.

The following measurements were conducted for the apple trees:

– Total yield (kg/plant),

– Assessment of the degree of root colonisation by arbuscular mycorrhizal fungi,

– Measurement of chlorophyll fluorescence in leaves.

The experiments were planned in a randomised block design. Eight combinations were applied in the experiments.

Experimental combinations:

1. Control

1. Biochar
2. Consortium of microorganisms 1
3. Consortium of microorganisms 2
4. Consortium of microorganisms 3
5. Biochar + Consortium of microorganisms 1
6. Biochar  + Consortium of microorganisms 2
7. Biochar + Consortium of microorganisms 3

Three consortia of microorganisms deposited in SYMBIO BANK of the National Institute of Horticultural Research in Skierniewice (IO-PIB) were selected for experiments with strawberry, cucumber and apple plants:

• Consortium 1 – TES10B3 Bacillus, TES5B21 Bacillus sp., GOS5B1 Promicromonospora sp., GOS10B9 Bacillus sp.
• Consortium 2 – Pi22B Pseudomonas, Pi25C Pseudomonas sp.,NAzot2 Klebsiella sp.
• Consortium 3 – TES5B10C Priestia, GOS5B22 Priestia sp.GOS10B151 Bacillus sp.

The prepared consortia of microorganisms were applied to all examined plant species at the end of June, at a rate of 15 liters for each species, through thorough soil spraying.

During the entire growing season maintance treatments were carried out.

The statistical analysis of the obtained results was performed using one-way analysis of variance with Tukey’s test, α=0.05, using the statistical software Statistica 13.3.

Molecular studies

In order to optimize the composition of microbial consortia to stimulate the growth and yield of strawberry, cucumber and apple plants and to accelerate the composting proces, molecular identification of strains of beneficial microorganisms will be continued in 2024. Moreover, the survival of applied strains of microorganisms in the soil will be assessed using the DGGE technique (Denaturating Gradient Gel Electropohoresis). 

Chlorophyll a fluorescence measurements

The photosyntesis efficiency in leaves expressed by chlorophyll fluorescence measurements were investigated. Chlorophyll fluorescence parameters were recorded on fully expanded leaves using a portable Pulse Amplitude Modulation (PAM) Chl fluorometer (FMS-1, Hansatech Instruments Ltd., King’s Lynn, Norfolk, United Kingdom). The measurements were performed in 3 replications (10 leaves per replication). The measurements were taken at the same time of day. The fiber optic of the FMS-1 was positioned using the PPF/temperature leaf clip at a 60◦ angle from the upper surface of the leaf, and the distance between the leaf surface and the fiber optic was kept constant for all measurements. Before chlorophyll a fluorescence measurements, the leaves were dark-adapted for 30 min to obtain oxidoreduction equilibrium of PSII-PSI electron transport carriers. The following parameters of chlorophyll fluorescence after dark adaptation were measured: F_V/F_M – the maximum potential photochemical reaction efficiency in PS II; F_V/F₀ – the activity of PS II – the maximum efficiency of water decomposition on the donor side of PSII.

The following parameters of light-adapted leaves were measured: Φ_PSII – quantum yield of photosystem II photochemistry, which is directly associated with the rate of electron transfer in PSII toward biochemical processes. This parameter measures the proportion of the light absorbed by PSII that is used in photochemistry and provides the rate of linear electron transport and so indicates overall photosynthesis; qP – photochemical quenching; ETR – electron flow rate through photosystems; Rfd – vitality index, a measure of potential photosynthetic activity under given light conditions and the interaction of the light phase reaction with biochemical reactions in the dark phase of photosynthesis.

In 2024, the evaluation of chlorophyll photosyntesis efficiency will be continued. 

PLANNED TASKS OF ECONUTRI PROJECT IN 2024

– Implementation of task WP2, participation in project-related meetings, ensuring proper execution of work, and providing the project coordinator with information on research results.

– Continuation of field experiments with strawberry cv. Lycia, cucumber cv. Octopus plants and apple trees of Gold Millennium variety.

– Preparation of microbiological consortia and their application to the soil.

– Maintenance treatments.

– Evaluation of growth and yield of strawberry, apple and cucumber.

– Molecular identification of strains of beneficial microorganisms and evaluation of survival in soil of applied microbial strains using the DGGE (Denaturating Gradient Gel Electropohoresis) technique.

– Preparation of results obtained from field experiments conducted during the 2024 growing season.