Conventional Mineral Fertilization Research Articles

Assessment of the Agronomic Value of Manure-Based Fertilizers

Producing manure-based fertilizers (MBFs) with specific nutrient ratios is a solution to overpassing the imbalance of nitrogen and phosphorus in manures, and a way to recycle manure’s nutrients, promoting sustainable agricultural practices. Several MBFs with different tailored N:P ratios (0.5:1, 1:1 and 2:1) were produced to determine their agronomic value in a pot experiment with oat (0.5:1 ratio: cattle manure with pig slurry (CaM+PiS), cattle manure with poultry manure (CaM+PoM) and poultry manure with superphosphate (PoM+SP); 1:1 ratio: poultry manure with cattle slurry (PoM+CaS) and poultry manure with pig slurry (PoM+PiS); 2:1 ratio: cattle slurry with the liquid fraction of cattle slurry (CaS+CaS-LIQ), pig slurry with the liquid fraction of pig slurry (PiS+PiS-LIQ) and poultry manure with urea (PoM+U)). The performance of these MBFs was compared with conventional mineral fertilizers (MFs) in sandy soils (Haplic Arenosols) with different nutrient requirements. Oat fertilized with PoM+SP (0.5:1) and PoM+PiS (1:1) led to yields similar to those obtained with the use of MFs (6.3 and 7.2 mg DM, respectively). The MBFs PoM+SP and PoM+PiS, as well as PiS+PiS-LIQ (2:1), were agronomically equivalent to the MFs. N uptake with those MBFs was equivalent to that obtained with the MFs. Replacing MFs with MBFs in the basal fertilization of oat was demonstrated to be a solution to turn agriculture more sustainable by recycling nutrients efficiently.

Analytical perception and kinesthetic engagement in evaluation of copper chloride crystallization patterns of wheat, grape juice and rocket samples from conventional, organic and biodynamic cultivation

BackgroundWhen a dihydrate cupric chloride solution is crystallized in a petri dish in the presence of extracts of food products, dendritic crystal patterns emerge. The degree of growth, ripening and decomposition of the product is reflected in these patterns as salient unities (gestalts) of phenomenological features. In the present study we evaluated wheat, grape, and rocket (arugula) samples grown under different farming systems, fertilization treatments or horn silica application. The hypothesis of the present study was: samples are more precisely differentiated with a kinesthetic engagement in the perception of the gestalt decomposition than with ranking solely based on analytical criteria.ResultsIn six out of seven panel tests with three different agricultural products grown with different methods, the following rankings for accelerated decomposability were derived:For wheat: biodynamic < organic < conventional (mineral fertilization and manure) < mineral (mineral fertilization only)For grapes: biodynamic < organic < conventional (mineral fertilization and compost)For rocket (arugula): biodynamic < organic < mineralFor rocket (arugula): with horn silica < without horn silica application.Analytical assessment was compared with kinesthetic priming of the evaluation panel. In six out of seven tests kinesthetic assessments (i) yielded more highly significant differences in ranking between the cultivation methods; (ii) clearly improved matching of the samples in a confusion matrix to the ranking of the cultivation methods; and (iii) generated lower RMSE values.ConclusionsKinesthetic engagement in gestalt evaluation proved superior to an evaluation based on analytical perception. Highly significant differences between biodynamic and organic variants and also between treatments with and without horn silica application were found in six out of seven tests. In five of the six tests the only difference between organic and biodynamic variants was the application of the biodynamic preparations. The results indicate increased resistance to deterioration of the biodynamic variants, in terms of lower degradation in the crystallization images. This prompts additional research to establish whether the crystallization method can serve as a universal test to monitor the stress resistance of plants.Graphical

Maize crop response to different levels of mineral and or-ganomineral fertilization associated with plant growth promoting bacteria (PGPBs)

Corn has a high nutritional requirement, especially with regard to NPK fertilization. However, the low efficiency of conventional fertilizers combined with the high cost of the input has limited the reach of high yields. The use of fertilizers with increased efficiency seeks to mitigate these limitations, reducing potential losses due to the gradual release of nutrients. The objective of this work was to compare the nutrition, growth and production of maize plants subjected to different doses and special NPK fertilizers fully applied at planting, as well as their residual effect on the soil. A randomized block design was used, in a 3 x 4 factorial scheme, with four replications. The first factor consisted of conventional mineral, polymer coated and organomineral fertilizers inoculated with PGPBs. The second factor was doses of 0, 60, 90 and 120 kg ha-¹ of NPK. Vegetative growth, foliar nutrition (N, P and K), yield growth components, productivity, profitability and P and K nutrient content remaining in the soil after cultivation were evaluated. The conventional mineral fertilizer presented higher production of dry biomass of the aerial part and profitability in relation to the special fertilizers. However, the special fertilizers presented better results in the vegetative and productive growth, in general, still showing a potential reduction of the applied doses, without compromising the grain yield, especially in the organomineral fertilization + PGPBs. The same showed greater residual effect of K in the soil, proving to be relevant longterm studies for better elucidation of these effects in the soil and subsequent culture.

Drip fertigation with treated municipal wastewater and soil amendment with composted sewage sludge for sustainable protein-rich rice cultivation

Rice paddy farming is threatened by global water scarcity, necessitating the adoption of novel water-saving cultivation practices. The purpose of this study is to determine the effects of drip fertigation with treated municipal wastewater (TWW) on a rice–soilsystem that is amended with composted sewage sludge (CSS). The treatments included flood irrigation with tap water (Control; T1), flood irrigation with TWW (T2), drip irrigation (DI) with TWW at 86% water consumption (T3), DI with TWW at 75% water consumption (T4), DI with TWW at 69% water consumption (T5), and DI with tap water at 86% water consumption (T6). The control was administered mineral fertilizers, and all other treatments received the same N amount (260 kg ha −1 ) from CSS. The results indicated that TWW drip fertigation had a significant beneficial effect on rice production by increasing (59.7 g pot −1 , T3) or maintaining (51.4 g pot −1 , T4) grain yield while conserving up to 25% of water when compared to conventional flood irrigation and mineral fertilizer application (52.9 g pot −1 ). In comparison to conventional farming, TWW drip fertigation in conjunction with CSS amendment significantly increased grain protein and Cu content while reducing As accumulation by 50%. Both CSS and TWW are effective at retaining soil fertility while avoiding unfavorable accumulation of As, Pb, Cd, Cu, and Zn. The novel cultivation techniques described herein have the potential to significantly improve the sustainability of rice farming in water-stressed areas, as well as integrated wastewater management strategies aimed at achieving sustainable development goals. • Rice farming can benefit from treated wastewater (TWW) and composted sludge (CSS). • TWW drip fertigation greatly increased rice yield and conserved up to 25% of water. • CSS and TWW reuse increased protein while lowering As contents by 50% in grains. • The practices effectively preserved soil fertility without toxic element buildup.

Comparative Evaluation of Mineral and Organo-Mineral Nitrogen Fertilization and the Role of Amino Acids as Plant Growth Promoters in Maize Cultivation

The challenge to increase nitrogen uptake efficiency in intensively cultivated soils without runoffs and atmospheric release has been difficult to handle and usually leads to the excess application of mineral fertilizers. In the present study, four combinations of two different N fertilizers and a control were used in maize cultivation to evaluate the use of different types of N fertilization in the case of agronomic and plant physiology characteristics, as well as the quantity and quality characteristics of maize’s yield. The results show that, when the full rate of mineral fertilization with the addition of half rate of organo-mineral fertilizer with amino acids (MF+OMAA/2) was used, maize presented a 16% yield increase in comparison with the control, followed by mineral fertilization (MF) with a 10% increase. Protein content was increased in all treatments by 3–6% compared to the control, with the conventional fertilization and the alternates with lower rates of mineral fertilization not differing significantly. The nitrogen content in the leaves of maize increased in both measurements (11–23% and 19–40% at 70 and 107 days after sowing, respectively) of the different fertilizer treatments compared to the control. The results of this study confirm that the organo-mineral fertilizer containing amino acids can be used as an alternative or additive N fertilization that can decrease the use of conventional mineral fertilizers or can result in improved seed productivity and protein content in maize farms.

Farmers’ Preferences for Fertilizers derived from Domestic Sewage and Kitchen Waste – A Discrete Choice Experiment in Germany

In view of increasing energy and resource scarcities, nutrient recycling from domestic wastewater is a promising way to obtain mineral fertilizers. Given the lacking evidence about the acceptance of recycling fertilizers by the farming sector, we elicited farmer preferences and willingness to pay (WTP) for selected attributes of mineral fertilizers made from domestic sewage and kitchen waste. We conducted a Discrete Choice Experiment with 206 German farmers and fitted a Random Parameter Logit (RPL) model. As-suming an average market price level of around 300 euros per tonne of N-P-K fertilizer, the choice exper-iment revealed that farmers not engaged in non-food production such as forage cultivation or renewable energies activities and without farmer-to-consumer direct marketing would accept a recycling fertilizer only together with a financial compensation via price discount of approximately 10%. The average WTP drops considerably if a fertilizer’s heavy metal contents are relatively high and if the absence of drug residues cannot be guaranteed, whereas a customizable nutrient composition and a constant supply availability would have a sales promoting effect. Farmers’ characteristics can only partly explain the notable heterogeneity of the WTP for the considered fertilizer attributes. Even though the WTP for a recycling fertilizer is on average less than that for a conventional mineral fertilizer, the estimated WTP standard deviations suggest that not all farmers expect a financial compensation via price discount when purchasing recycling fertilizers.

Integrated biofertilization using yeast with cyanobacteria on growth and productivity of wheat

BackgroundThe heavy use of conventional mineral fertilization considerably increased wheat growth and yield components. However, the excessive nitrogen fertilization accounts for large expenses on farmers’ budget and has negative environmental drawbacks to soil and water ecosystems. Recently, establishing wheat plants associations with a variety of N2-fixing cyanobacteria and/or growth promoting microorganisms in farming systems as nutrients source is seen as ecofriendly and economically feasible solution.ResultsIn this work, the influence of different nitrogen (N) levels (100% N, 75% N, and 50% N as urea) and cyanobacteria (Cy) and/or yeast (Y) inoculation each alone or both in combination with different nitrogen levels were assessed on two different wheat (Triticumae stivum L.) genotypes (Sids-14 and Giza-171) through field experiments over two consecutive seasons (2019/2020 and 2020/2021). Although, the full recommended dose (FRD) (100% N) showed the highest chlorophyll (Chl) a, b content during tillering stage, grains quality (NPK-uptake, protein%), and wheat yield components in both genotypes. The integrated inoculation of cyanobacteria and yeast with 50% N, 75% N-fertilization enhanced wheat growth characteristic (Chl a,b) and upgraded soil microbial community (nitrogenase activity and CO2 evolution) in Sids-14 and Giza-171. Cy combined with Y and partial N-fertilization levels enhanced NPK-uptake Kg/fed and protein% in wheat grains in the two wheat genotypes. Moreover, this combination recorded a wheat yield components (plant height, number of spikes/m2, number of grains/spike, 1000 grains wt (gm) and grains yield (tonne/fed) insignificantly different from those obtained by FRD in wheat cultivation.ConclusionThe integrated application of cyanobacteria with yeast and 50% N or 75% N-fertilization improved soil fertility index and promoted NPK- uptake, protein% and wheat yield components, showing comparable values to conventional chemical fertilization. Cyanobacteria combined with yeast inoculation had socio-economic benefits as it can save about 25–50% of the required mineral nitrogen fertilizers for wheat crop production.

Impact of Super-High Density Olive Orchard Management System on Soil Free-Living and Plant-Parasitic Nematodes in Central and South Italy.

Simple SummarySuper-high density olive orchards are spreading in Italy to reduce production costs and increase yields per hectare. The objective of this study was to assess the orchards’ effect on the soil nematode community in five sites located in the main Italian olive cultivation areas compared to the adjacent traditional olive orchard system. Super-high density olive orchard management combined with conventional tillage and mineral fertilization decreased total organic carbon compared to traditional management. The soil nematode community was affected by the depletion of organic matter, especially for plant-parasitic nematodes, which increased. Moreover, this investigation evidenced that the Super-high density olive orchard management system could change the soil plant-parasitic nematode composition of olive orchards. In fact, the families Telotylenchidae, Paratylenchidae, Meloidogynidae, and Criconematidae were favored in the Super-high density olive orchard system, while Longidoridae, Heteroderidae, and Pratylenchidae were disadvantaged. However, conservative and sustainable soil management might maintain or improve the soil nematode community functionality and reduce plant-parasitic nematodes.The soil nematode community plays an important role in ecosystem services. The objective of this study was to assess the effect of Super-high density (SHD) olive orchards on the nematode community in five sites with different soils, climates, and cultivars. At each site, the SHD management system was compared to the adjacent olive orchard traditional (TRAD) system, in which the same soil management and phytosanitary measures were applied. Soil management was assessed by total organic carbon content (TOC), while the soil nematode community was evaluated using the nematode taxa abundances and soil nematode indicators. TOC was significantly decreased in the SHD olive orchard system compared to TRAD in the sites characterized by conventional tillage and mineral fertilization. The two-way ANOSIM analysis on nematode abundance showed no difference between the two olive management methods, instead showing only a significant difference per site mainly due to variabilities in plant-parasitic nematode assemblage. However, a negative impact of SHD management was evident in environments stressed by summer droughts and conventional tillage: the ratio of obligate plant-parasites to bacterivores and fungivores (Pp/(B+F)) was significantly higher in SHD than in the TRAD olive orchard system, and the prey-to-predator θ mass ratio showed the lowest values in the sites under organic fertilization or green manure. The canonical correspondence analysis showed that the free-living nematodes were only slightly affected by SHD olive orchards; instead, the presence of plant-parasitic nematodes families such as Telotylenchidae, Paratylenchidae, Meloidogynidae, and Criconematidae was favored, in comparison to Longidoridae, Heteroderidae, and Pratylenchidae.

Use of compost in the uptake mitigation of arsenic in Beta vulgaris L. var. cicla.

Arsenic (As) may represent a risk for crop yield quality and human health since it may accumulate in the edible plant organs with the potential of leading to acute or chronic toxic effects in varied segments of the population. Management of soil fertility through compost has proven to be a valuable practice for increasing and maintaining soil organic matter, with nutritional benefits for crops. This work aimed to evaluate Swiss chard yield and the change in the bioavailability, bioaccumulation, and partitioning of As in the response of the use of compost or conventional mineral fertilization in an open-field trial conducted in a volcanic area in central Italy characterized by the natural contamination of As in soil. Compost treatment led to a short-term increase trend in soil organic carbon, total nitrogen, and available phosphorus in a significant way. In the compost-amended plots, the mitigation of the As uptake was detected in leaves, which are the edible part of Swiss chard. The As bioaccumulation factor in leaves of Swiss chard and the translocation factor for leaves/roots were also decreased using compost. Fertilization by compost can improve soil fertility, sustain Swiss chard production, and mitigate As accumulation in leaves of this crop grown in a naturally As-contaminated soil. © 2022 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Cattle Manure Alters the Soil Nutritional Status and Soybean Yield (Glycine max L. Merr.)

Soybean is one of the most important crops globally, despite significant numbers the crop in the Cerrado biome presents low natural fertility with a higher demand for fertilization. Seeking to improve the production of culture by reducing costs there is the possibility of using organic waste, which can be a very advantageous and interesting option when well used. The objective of this work was to evaluate the physiological, nutritional, and productive aspects of soybean crops grown with cattle manure associated with chemical fertilizers. The experimental design was in randomized blocks with eight replications (4 for destructive analyses and 4 for grain harvesting). The treatments were composed of 5 doses of cattle manure (0.0, 2.5, 5.0, 10.0, and 20.0 t ha-1) and control treatment (Control) without fertilization, without the use of manure and mineral fertilizer. The cattle manure provided a positive increase in the increase of levels of Ca, Mg, M.O, P, K, Fe, Zn and in the characteristics of plant height, stem diameter, soybean node number, dry weight of shoot, Falker chlorophyll index, root length and dry weight of root. The dose of 20.0 t ha-1 was the best response dose for soil nutritional conditioning for both physical and chemical characteristics, with an average increase of 68.26% in a comparison with only the use of conventional mineral fertilization.

Composted Sewage Sludge Application Reduces Mineral Fertilization Requirements and Improves Soil Fertility in Sugarcane Seedling Nurseries

Sugarcane demands large amounts of nutrients to reach a high level of productivity. Nutrients are generally supplied by mineral fertilizers, but their high costs and negative environmental impacts have generated interest in greater use of organic nutrient sources such as composted sewage sludge (CSS). In this study, we evaluated changes in soil chemical properties after the application of CSS or CSS/mineral fertilizer (MF) combinations to soil containing sugarcane seedlings under nursery conditions. Treatments included: T1: conventional mineral fertilization (MF) without application of CSS, T2: 100% of the recommended MF (06–30–24); T3: application of 2.5 Mg−1 CSS; T4: 5.0 Mg−1 CSS, T5: 7.5 Mg−1 CSS, T6: 2.5 Mg−1 CSS and 50% MF, T7: 5.0 Mg−1 CSS and 50% MF, T8: 7.5 Mg−1 CSS and 50% MF, T9: 2.5 Mg−1 CSS and 100% MF, T10: 5.0 Mg−1 CSS and 100% MF, T11: 7.5 Mg−1 CSS and 100% MF. Soil chemical properties were evaluated from the soil surface (0.0–0.25 m) and subsurface (0.25–0.50 m) horizons. The results showed that the increase in CSS application did not affect soil organic matter content at either depth, while Zn concentrations increased in the soil subsurface horizon. The application of CSS at 5.0 Mg ha−1 with or without 50% MF resulted in the highest pH values, sum of bases, cation-exchange capacity, P, K, Ca, Mg, Cu, and Zn in surface horizons. The use of CSS as an organic fertilizer in sugarcane nurseries improves soil fertility, reduces mineral fertilizer requirements, and, thus, facilitates the sustainable disposal of sewage sludge.

Effect of Fertilisation with Ash from Biomass Combustion on the Mechanical Properties of Potato Tubers (Solanum tuberosum L.) Grown in Two Types of Soil

The aim of the research was to determine the effect of fertilising with various doses of ash from biomass combustion (D2–D6) compared to control plots and classic NPK (D1) fertiliser on the morphological and mechanical properties of potato tubers (Solanum tuberosum L.). The field experiment was carried out in the years 2019–2021 (south-eastern Poland, 49°59′ N, 21°57′ E) on two types of soil: Gleyic Chernozem (silty loam) and Haplic Luvisol (silt). The values of mechanical parameters, such as the peel and flesh punching force (FD), deformation (DR) and energy (ED) needed to destroy the test sample, were assessed. The biometric features of the tubers were also assessed. It was found that tubers obtained from the experimental fields where D3 and D4 ash fertiliser doses were applied (corresponding to doses of 188 and 282 kg∙ha−1 K) had the highest tuber yields and the highest resistance to mechanical damage under quasi-static loads. Ash from biomass combustion can be an alternative to conventional mineral fertilizers and can be used in the development of mineral fertilization plans for sustainable agriculture, which will help to solve the problem of storage of this waste.

Volcanic Ash Application in Agricultural Practice

For the first time in international practice, agricultural experiments were carried out to introduce volcanic ash from the Kamchatka Peninsula in combination with conventional mineral fertilizers into ocherous volcanic soils (Andosols Acroxic). According to various variables of field experiment, yield increases were obtained relative to the background: for potatoes (Solanum tuberosum) by 31–63% in 2014, by 7–19% in 2017 and by 14–31% in 2018; on timothy (Phleum pretense) by 21-50% in 2015. Production experience in the cultivation of annual forage grasses in 2016 showed an increase in yield by 32%. In addition, the crude protein in forage grasses and the content of starch potato tubers also increase, and potatoes have better resistance to potato diseases.

An Assessment of the Effects of Applying Ash from the Thermal Disposal of Sewage Sludge for Fertilizing Energy Plants Using the Example of Giant Miscanthus (Miscanthus sinensis giganteus)

The aim of the research was to determine the possibility of using ash from the thermal utilization of municipal sewage sludge as a fertilizer in the cultivation of giant miscanthus (Miscanthus sinensis giganteus) for energy purposes. An attempt was also made to determine the optimal level of fertilization with ash from the thermal utilization of municipal sewage sludge in the commodity cultivation of miscanthus. It was assumed that the ash produced after thermal utilization of municipal sewage sludge could replace conventional mineral fertilizers. To prove the thesis, laboratory experiments of the miscanthus cultivation miscanthus were carried out. The results allowed to determine the optimal fertilization dose for miscanthus to be used in the next stage of the field research. Miscanthus does not pose a succession threat due to the method of reproduction in central Europe; therefore, its cultivation may remain under control. The research showed that for fertilization of miscanthus × giganteus crops, the ashes from thermal utilization of municipal sewage sludge could be used effectively. In experimental crops, it was shown that the optimal level of miscanthus fertilization in terms of yield was 8.32 g of ash per pot and 0.1 g of nitrogen per pot. As a result of laboratory tests, based on biometric features, the most favorable dose of ash and nitrogen fertilization from thermal utilization of municipal sewage sludge for use in field conditions was selected. The dose amounted to 3.7 t of ash∙ha−1 and 45 kg of nitrogen∙ha−1. In order to reduce the costs of cultivation, it was possible to abandon the use of nitrogen fertilizers since their omission did not cause a significant drop in yield. It is necessary to continue research in the field in order to confirm the correctness of the results obtained from laboratory tests.

Green manuring with crimson clover as an alternative to mineral fertilization in maize production

Role of mineral fertilizers is to complement the soils’ indigenous supply of minerals for crop plants nutrition. Among the mineral nutrients, nitrogen is generally considered as the most yield-contributing. Obtaining nitrogen from legumes is potentially more sustainable than from industrial sources. Crimson clover (Trifolium incarnatum L.) has long been appreciated as cover crop grown for green manuring due to its capability for binding the atmospheric nitrogen into plant-available form. Green manuring effects of crimson clover for succeeding maize crop were tested in 2019 year on two locations of Northeastern Croatia differing in soil texture: 1) on the site A where the soil was compact and dominated by clay and 2) on the site B where the soil was loose and dominated by loam. The research was conducted in a year with favourable rainfall during maize vegetation. Results have shown that green manuring with crimson clover for maize as the main crop delivered somewhat lower maize grain and aboveground mass yields than the conventional full-dose mineral fertilization on deep fertile soils around Osijek (Northeastern Croatia). When compared to conventional agronomy, green manuring was associated with additional agrotechnical operations required for crimson clover cover crop establishment and its herbage incorporation into soil prior to seeding main maize crop. Research should be continued in more different environments (year × location combinations) in order to produce reliable evaluation of crimson clover’s green manuring services.

Soil Quality Assessment after 25 Years of Sewage Sludge vs. Mineral Fertilization in a Calcareous Soil

The aim of this work was to identify the most sensitive soil quality indicators and assess soil quality after long-term application of sewage sludge (SS) and conventional mineral fertilization for rainfed cereal production in a sub-humid Mediterranean calcareous soil. The treatments included six combinations of SS at different doses (40 t ha−1 and 80 ha−1) and frequencies (every 1, 2 and 4 years), plus a control with mineral fertilization, and a baseline control without fertilization. Twenty-five years after the onset of the experiment, 37 pre-selected physical, chemical and biological soil parameters were measured, and a minimum data set was determined. Among these indicators, those significantly affected by treatment and depth were selected as sensitive. A principal component analysis (PCA) was then performed for each studied depth. At 0–15 cm, PCA identified three factors (F1, F2 and F3), and at 15–30 cm, two factors (F4 and F5) that explained 71.5% and 67.4% of the variation, respectively, in the soil parameters. The most sensitive indicators (those with the highest correlation within each factor) were related to nutrients (P and N), organic matter, and trace metals (F1 and F4), microporosity (F2), earthworm activity (F3), and exchangeable cations (F5). Only F3 correlated significantly (and negatively) with yield. From these results, we concluded that soil quality can be affected in opposite directions by SS application, and that a holistic approach is needed to better assess soil functioning under SS fertilization in this type of agrosystem.

Influence of the use of slow-release phosphate fertilizers on the growth and production of chili peppers

In general, fertilization recommendations for pepper are old and scarce. Because pepper is a semi-perennial crop with high yield potential and dependence on phosphorus (P), an extremely important element, as it participates in several metabolic processes, it is necessary to look for efficient alternatives for phosphatefertilization, due to its low availability and high adsorption capacity in most Brazilian soils. Slow-release fertilizers have been shown to be an excellent alternative to conventional mineral fertilization. Therefore, the objective of this study was to evaluate the effect of different sources of P on growth and yield of hot pepper (Capsicum frutescens L.). An experiment was carried out in a greenhouse in the JK campus of UFVJM, Diamantina -MG, Brazil, arranged in a completely randomized design with eleven treataments(absence of fertilization, mineral treatment, organic treatment and four slow-release phosphate sources: pelleted organomineral, granulated organomineral, MAP coated and triple formulated, at doses of 150 and 300 kg ha-1 of P2O5). Growth variables, fresh and dry matter accumulation and yield were evaluated 180 days after planting. The pelleted and granulated organomineral treatments at the dose of 300 kg ha-1 of P2O5,promoted the best results for the parameters dry mass of root, number of fruits per plant, fresh and dry mass of fruits and total yield. Such results can be explained by the better efficiency of P release and the better absorptionof this nutrient by the plant, making it an excellent option in relation to conventional sources commonly adopted.

Investigation on the improved electrochemical and bio-electrochemical treatment processes of soilless cultivation drainage (SCD)

The soilless crop cultivation under cover generates wastewater called soilless cultivation drainage (SCD), being a nutrient-rich overflow. The average concentration of phosphorus- and nitrogen-based pollutants from soilless tomato cultivation usually ranges from 35.4 to 104.0 mg P/L and from 270.0 to 614.9 mg N/L, respectively. In bio-electrochemical reactors, nitrogen and phosphorus are removed via biological denitrification, electrochemical nitrate reduction, bio-electrochemical reduction, and electrocoagulation. The novelty of this study is due to the use of alternating current (AC), which can both mitigate the corrosion on the anode and solve the issue of insoluble oxide build-up on the cathode. Additionally, and crucially, it promotes bacterial growth and activity. The aim of the present study was to determine (1) the effectiveness of soilless cultivation drainage treatment methods that employ biological and electrochemical processes, with consideration given to (2) the quantity and quality of the produced sludge as a potential nutrient-rich product. The bio-electrochemical reactor proved more effective than the electrochemical one and ensured a high TP and TN removal efficiency exceeding 97% and 66%, respectively. The resulting sludge was rich in such elements as calcium, potassium, carbon, phosphorus, and nitrogen, and as such may serve as a viable alternative to conventional mineral fertilizers.

Reduced tillage, cover crops and organic amendments affect soil microbiota and improve soil health in Uruguayan vegetable farming systems.

Conventional tillage and mineral fertilization (CTMF) jeopardize soil health in conventional vegetable production systems. Using a field experiment established in Uruguay in 2012, we aimed to compare the soil restoration potential of organic fertilization (compost and poultry manure) combined with conventional tillage and cover crop incorporated into the soil (CTOF) or with reduced tillage and the use of cover crop as mulch (RTOF). In 2017, table beet was cultivated under CTMF, CTOF and RTOF, and yields, soil aggregate composition and nutrients, as well as soil and table beet rhizosphere microbiota (here: bacteria and archaea) were evaluated. Microbiota was studied by high-throughput sequencing of 16S rRNA gene fragments amplified from total community DNA. RTOF exhibited higher soil aggregation, soil organic C, nutrient availability and microbial alpha-diversity than CTMF, and became more similar to an adjacent natural undisturbed site. The soil microbiota was strongly shaped by the fertilization source which was conveyed to the rhizosphere and resulted in differentially abundant taxa. However, 229 amplicon sequencing variants were found to form the core table beet rhizosphere microbiota shared among managements. In conclusion, our study shows that after only 5 years of implementation, RTOF improves soil health under intensive vegetable farming systems.

Assessing the environmental behavior of alternative fertigation methods in soilless systems: The case of Phaseolus vulgaris with struvite and rhizobia inoculation

Urban agriculture, while being a promising solution to increase food sovereignty in cities, can lead to an unprecedented discharge of nutrient and fertilizer-related emissions into the urban environment. Especially relevant are nitrogen (N) and phosphorus (P), due to their contribution to marine and freshwater eutrophication. Therefore, alternative methods of fertilization need to be put into practice to avoid such impacts to the surrounding environment. Struvite, has been studied as a potential slow releasing fertilizer due to its high P content, while the bacteria rhizobium has been used to fix N directly from the atmosphere. Legumes, like the common bean are N-demanding crops capable of symbiosis with the bacteria rhizobium and have previously shown positive responses to fertilization with struvite. This study aims to analyze the environmental performance of plant production in hydroponic systems combining rhizobium inoculation and struvite (2 g, 5 g, 10 g, 20 g) irrigated with a N and P deficient nutrient solution, using life cycle analysis (LCA). The nutrient content of in- and out-going irrigation was analyzed as well as in plants and beans. The functional unit for the LCA was 1 kg of fresh beans. The results obtained indicate a yield reduction of 60% to 50% in comparison to the control which was irrigated with a full nutrient solution. The impacts from operational stage are less in all impact categories, where most significant reductions up to 69% and 59% are seen in marine-eutrophication and global warming respectively. Although the infrastructure does not change between treatments, its impacts increase due to the lower yields. We determine that below a 10% of the control yield, the alternative systems have more impact than the use of conventional mineral fertilizers in almost all impact categories, thus pointing to the importance of infrastructure to truly reduce environmental impacts for urban agriculture.