An Integrated Approach to Assessing the Soil Quality and Nutritional Status of Large and Long-Term Cultivated Rice Agro-Ecosystems

Aschonitis, Vassilis; Karydas, Christos; Iatrou, Miltos; Mourelatos, Spiros; Metaxa, I.; Tziachris, Panagiotis; Iatrou, George

doi:10.3390/agriculture9040080

Cited by 10 publications

(6 citation statements)

References 67 publications

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“…To define ecological thresholds where ecosystem attributes suddenly change due to small variations in specific environmental drivers, Threshold Indicator Taxa Analysis (TITAN) is a promising method as it provides not only the detection of potential indicator taxa, but rather as it provides information for potential community-level change points [ 51 , 84 ], whereby both (micro-) biological parameters such as taxa abundances [ 85 , 86 ] and chemical parameters such as targeted nutrient concentrations can be used [ 87 ]. TITAN was carried out using the R package “TITAN2” [ 51 , 84 ].…”

Section: Methodsmentioning

confidence: 99%

Microbiome Diversity and Community-Level Change Points within Manure-Based Small Biogas Plants

et al. 2020

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Efforts to integrate biogas plants into bioeconomy concepts will lead to an expansion of manure-based (small) biogas plants, while their operation is challenging due to critical characteristics of some types of livestock manure. For a better process understanding, in this study, three manure-based small biogas plants were investigated with emphasis on microbiome diversity. Due to varying digester types, feedstocks, and process conditions, 16S rRNA gene amplicon sequencing showed differences in the taxonomic composition. Dynamic variations of each investigated biogas plant microbiome over time were analyzed by terminal restriction fragment length polymorphism (TRFLP), whereby nonmetric multidimensional scaling (NMDS) revealed two well-running systems, one of them with a high share of chicken manure, and one unstable system. By using Threshold Indicator Taxa Analysis (TITAN), community-level change points at ammonium and ammonia concentrations of 2.25 g L-1 and 193 mg L-1 or volatile fatty acid concentrations of 0.75 g L-1were reliably identified which are lower than the commonly reported thresholds for critical process stages based on chemical parameters. Although a change in the microbiome structure does not necessarily indicate an upcoming critical process stage, the recorded community-level change points might be a first indication to carefully observe the process.

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Section: Methodsmentioning

confidence: 99%

Microbiome Diversity and Community-Level Change Points within Manure-Based Small Biogas Plants

et al. 2020

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“…If an efficient nitrogen topdressing management advice is provided to the growers timely, the spatial availability of P and K can also be addressed; P and K explain a large proportion of the yield variance [3]. Fertility issues of rice cultivation in the soils of the area have been discussed by [18].…”

Section: Resultsmentioning

confidence: 99%

“…The company has been monitoring and consulting about 1500 ha of rice (shared between 15 different farms) throughout Greece all these years, providing vertical precision farming support to the growers (from crop heterogeneity detection, to interpretation, decision-making, and applications). The company is steadily receiving scientific and technical backup by the Soil and Water Resources Institute, Hellenic Agricultural Organization-Demeter (see Aschonitis et al, (2019) [18]).…”

Section: Introductionmentioning

confidence: 99%

Topdressing Nitrogen Demand Prediction in Rice Crop Using Machine Learning Systems

Iatrou¹,

Karydas²,

Iatrou³

et al. 2021

Agriculture

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This research is an outcome of the R&D activities of Ecodevelopment S.A. (steadily supported by the Hellenic Agricultural Organization—Demeter) towards offering precision farming services to rice growers. Within this framework, a new methodology for topdressing nitrogen prediction was developed based on machine learning. Nitrogen is a key element in rice culture and its rational management can increase productivity, reduce costs, and prevent environmental impacts. A multi-source, multi-temporal, and multi-scale dataset was collected, including optical and radar imagery, soil data, and yield maps by monitoring a 110 ha pilot rice farm in Thessaloniki Plain, Greece, for four consecutive years. RapidEye imagery underwent image segmentation to delineate management zones (ancillary, visual interpretation of unmanned aerial system scenes was employed, too); Sentinel-1 (SAR) imagery was modelled with Computer Vision to detect inundated fields and (through this) indicate the exact growth stage of the crop; and Sentinel-2 image data were used to map leaf nitrogen concentration (LNC) exactly before topdressing applications. Several machine learning algorithms were configured to predict yield for various nitrogen levels, with the XGBoost model resulting in the highest accuracy. Finally, yield curves were used to select the nitrogen dose maximizing yield, which was thus recommended to the grower. Inundation mapping proved to be critical in the prediction process. Currently, Ecodevelopment S.A. is expanding the application of the new method in different study areas, with a view to further empower its generality and operationality.

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“…For nutrient analyses, available phosphorus (P) was determined according to the Olsen method [24], while the concentrations of K, Ca, Mg, Na, Cd, Co, Cr, Ni, Pb, Mn, Fe, Zn, and Cu were measured as described in [25].…”

Section: Harvest and Analytical Measurementsmentioning

confidence: 99%

Exploitation of Liquid Digestate as the Sole Nutrient Source for Floating Hydroponic Cultivation of Baby Lettuce (Lactuca sativa) in Greenhouses

Ντίνας¹,

Bantis

Κουκουνάρας

et al. 2021

Energies

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Sustainable agriculture relies on replacing fossil-based mineral fertilizers, which are highly cost-energetic to produce, and demand extensive use of scarce natural resources. Today, agronomic practices within the concept of circular economy are emerging and, as such, the exploitation of digestate as a biofertilizer and soil amender is extensively investigated. This study aimed at evaluating the agronomic potential of liquid digestate as the sole nutrient source for hydroponic cultivation of baby lettuce in greenhouses. Growth rate, physiological responses, concentration of secondary metabolites, and nutrient uptake were compared between baby leaf lettuce grown in digestate in concentrations of 5, 10, and 20% diluted in water (either with or without pH adjustment) and in Hoagland solution (control). Results showed that the production yield was negatively correlated with the concentration of the added digestate. Nevertheless, the antioxidant capacity was significantly enhanced in 5 and 10% liquid digestate treatments compared to the control. Additionally, the nutrient composition in the baby leaf lettuce and the reduction in nutrient concentrations in the growth media demonstrated efficient mineral uptake by the plants. Thus, the application of liquid digestate as a fertilizer in hydroponic systems is a promising practice to recover residual resources, leading to the transition towards more sustainable greenhouse production.

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An Integrated Approach to Assessing the Soil Quality and Nutritional Status of Large and Long-Term Cultivated Rice Agro-Ecosystems

Cited by 10 publications

References 67 publications

Microbiome Diversity and Community-Level Change Points within Manure-Based Small Biogas Plants

Microbiome Diversity and Community-Level Change Points within Manure-Based Small Biogas Plants

Topdressing Nitrogen Demand Prediction in Rice Crop Using Machine Learning Systems

Exploitation of Liquid Digestate as the Sole Nutrient Source for Floating Hydroponic Cultivation of Baby Lettuce (Lactuca sativa) in Greenhouses

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