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Organo-mineral fertilizers (OMFs) with low organic carbon (Corg) content have been associated with higher mineral fraction nutrient use efficiency. However, the extraction of peat, which is typically used in these OMFs, from endangered ecosystems causes long-time stored Corg to mineralize and to be released back into the atmosphere as carbon dioxide (CO2). This study analyzes the replacement of peat in OMFs with biowaste materials. These materials, considered organic byproducts that microorganisms and other living things can decompose through composting and aerobic or anaerobic digestion, offer a viable opportunity. This study investigated three stabilized biowastes—green compost (GC) from pruning residues, municipal solid waste compost (MSWC), and manure-based vermicompost (VC)—as the organic matrices for granular OMFs. These matrices were impregnated with dissolved ammonium sulfate and urea and used to coat diammonium phosphate granules. Each biowaste OMF contained 7.5% Corg, 20% mineral N, and 10% mineral P2O5 (OMF20 − 10). Fertilizers with high nutrient concentrations have the advantage of requiring low application volumes, facilitating their application in the field. Biowaste OMFs were compared with peat OMFs with the same Corg-N-P2O5 concentration. Peat and MSWC were also used to create OMFs containing 7.5% Corg, 10% mineral N, and 5% mineral P2O5 (OMF10 − 5). A 75-day tunnel trial was conducted under semi-controlled conditions using tomato plants (Solanum lycopersicum L.) fertilized to an equivalent of 81 mg N kg−1 soil and 18 mg P kg−1 soil. Controls included no fertilization (N0P0) and mineral N and P fertilization (MFNP). The Soil Plant Analysis Development (SPAD) chlorophyll meter and the BBCH (from German Biologische Bundesanstalt, Bundessortenamt und CHemische Industrie) scale as well as the number of shoots were measured over time, as berry and total aboveground yield, N and P uptakes, and N and P use efficiencies (NUE and PUE, respectively) were calculated at harvest. All treatments outperformed the control N0P0 in most indicators. Peat20 − 10 did not have more berry yield than other OMF20 − 10; however, the higher number of shoots indicated a higher potential yield in the event of prolonging the experiment. At the end of 75 days, VC20 − 10 and MSWC20 − 10 showed similar PUE to peat, suggesting that those materials can be used as replacements. In the case of OMF10 − 5, MSWC10 − 5 had yield and N and P uptakes like peat OMFs, confirming the potential use of MSWC as peat replacement even at different nutrient concentrations. This research provides reassuring evidence of the effectiveness of biowaste OMFs, offering a positive outlook for sustainable agriculture. However, their use is not recommendable for short growing seasons.

Abstract Vermicompost (VC), a stabilized organic material with high organic and humic carbon, and favorable aggregation properties, was tested as a fraction of organo‐mineral fertilizers (OMFs), where organic and mineral fractions interact in hotspot areas with surrounding soil. Solutions containing 33P radioisotope and 15N‐labeled mineral fertilizers were combined with VC at two ratios of organic carbon (Corg) to mineral nitrogen (N) and phosphorus (P) (OMF7.5C and OMF15C) to simulate OMF granules. Control treatments included unfertilized soil (N0P0), mineral fertilizer (MFNP), and sole VC at two rates (OF7.5C and OF15C). Nitrogen and P uptake by Italian ryegrass (Lolium multiflorum) were measured over in 8 weeks. Furthermore, MFNP, OMF7.5C, and OMF15C treatments were incubated for 10 days without plant to measure atom% 15N excess and 33P radioactivity, as indicators of N and P movement from two soil layers (surrounding fertilizer hotspot and below it). In the pot study, OMF15C caused 24% lower biomass and less nutrient recovery derived from fertilizer (N, 11% and P, 8.5%), compared to MFNP. In the incubation study, OMF15C exhibited +19% atom% 15N excess in the combined two soil layers, relative to MFNP, and +28% 33P radioactivity in the soil surrounding the hotspot, and −89% in the soil below it. We interpreted this as a reduction in nutrient availability of the combined VC + mineral fertilizers, due to lower P mobility in soil. The combination of VC with mineral fertilizers can reduce P movement in soil. A higher Corg:N:P ratio resulted in lower nutrient use efficiency in 2 months.

Phosphorus (P) is an essential nutrient for maize production, but in temperate areas the P uptake during early growing stages can be limited due to low soil temperature, even though the soil was tested high in P. The objective of this study was to assess the effects of nitrogen and phosphorous (NP) starter fertilisation during early growth stages and its carryover until maize harvest, in mineral-fertilised or manured systems. A field experiment was carried out in north-west Italy during the 2019 and 2020 growing seasons. The trial compared sub-surface placement of NP (diammonium phosphate) or N alone (ammonium nitrate) in bands close to the maize seed furrows, in differing long-term (LT) fertilisation managements: two doses of urea (Min-L and Min-H), two doses of bovine slurry (Slu-L and Slu-H) or two doses of farmyard manure (Fym-L and Fym-H). The two rates, low (L) and high (H), corresponded to 170 and 250 kg N ha−1 year−1 respectively. Compared to N fertilisation, NP starter fertilisation improved early maize growth assessed by leaf area index (LAI) and shoot dry weight (SDW) in all systems. The effects differed between the two years (2019: LAI + 63%, SDW + 67%; 2020: LAI + 36%, SDW + 38%), as 2019 was cool during the first growth. Higher LAI and SDW values were confirmed at crop flowering in the mineral-fertilised systems only. As shoot growth was enhanced by NP starter fertilisation, anthesis occurred 1 day earlier in all systems. However, a response to NP starter fertilisation at harvest was recorded in mineral-fertilised systems only (+1.3 and +3.2 t ha−1 in Min-L and Min-H, respectively). The uptake of P, used as a true indicator of soil nutrient availability, increased with increasing soil Olsen P until 39 mg kg−1. These results suggest that soil test thresholds should be revised for points above which P fertilisation should be suspended.

Cover crop use in organic rice cropping systems efficiently manages the two most limiting factors in organic agriculture - weed competition and nutrient availability. Nonetheless, cover crop biomasses on soil surfaces under the anaerobic conditions in flooded rice systems produce organic acids (mainly acetic acid) that cause early phytotoxicity to rice seedling coleoptile and roots. This study evaluated the dose-response of acetic acid on germination rates and post-germination growth traits (coleoptile, first leaf, and roots). Under controlled conditions, the seeds of three rice varieties (Sant’Andrea, Salvo, and Selenio) were immersed in acetic acid concentrations (0, 9, 18, 36, 54, and 72 ppm) for eight days. Germination results suggest that acetic acid likely scarred var. Salvo, based on a 15% faster germination rate compared to untreated controls. Across all varieties, increased acetic acid concentrations never slowed germination. During post-germination growth stages, root phytotoxicity was always more evident than shoot phytotoxicity, although the responses varied among the varieties. Root length damage appeared first at acetic acid concentrations of 36 ppm in var. Sant’Andrea and Selenio, and at 54 ppm in var. Salvo. Root length measurements provided explicit and speedy information on varietal tolerance to acetic acid and, consequently to cover crop fermentation and suggested that direct observation of root damage in paddy fields is valuable for prompt water management decisions, such as flooding interruption. Further development of this method may lead to more complete varietal screening and identification of related genetic traits responsible for tolerance. Highlights - Based on genotype, increasing acetic acid levels in flooding waters can speed rice germination. - Roots are more sensitive than shoots to acetic acid phytotoxicity during very early germination. - Early root length impairments provide information on tolerance to acetic acid phytotoxicity. - A slower germination rate may induce higher tolerance to green mulching.

A field study was carried out in 2017 and 2018 in two Italian rice farms (at Livorno Ferraris and Rovasenda) to assess the effect of using cover crops as green mulching on weed control and rice yield. In each site, three different rice fields were sown after rice harvest with either Vicia villosa, Lolium multiflorum, or a mixture of both (V. villosa 40% + L. multiflorum 60%); at Rovasenda a small percentage of Brassica napus and Triticale was also present in the mixture. An additional field at both sites without cover crop was considered as a control reference. Rice was broadcasted sown within the cover crop in May. After few days, the cover crop was terminated in half of each field using a roller-crimper, while in the other half it was terminated by shredding. Within 10 days, the fields were flooded for about a week to promote the degradation of the cover crop biomass. Then, the fields were cultivated in flooding conditions without further weed control. Weed density and weed cover were evaluated thrice during the growing season. At harvest, rice yield and harvest index were determined. Mixed nested ANOVAs were performed for each site to assess the effect of cover crop species, termination technique, and the interaction between cover crop and year. L. multiflorum showed a high biomass before termination, while V. villosa had a more variable development. At Rovasenda, V. villosa growth was limited because of the combination of scarce emergence due to sod-seeding and frost damage. In general, green mulching significantly affected weed density. The best weed suppression was observed with L. multiflorum and mix at Rovasenda, with values of weed density 5 t ha-1) was observed in 2018 in the shredded mixture at Rovasenda and in V. villosa at Livorno Ferraris in 2017. Generally, control fields showed lower yields (1-3 t ha-1) at both sites. The termination methods did not significantly affect both weed density and rice yield. The results highlighted that green mulching could reduce weed infestations, even though alone is not able to completely avoid weed development. Some critical issues of the technique were observed, such as the need of a good cover crop establishment, that eventually results in abundant biomass production and significant weed suppression. Highlights - Green mulching reduces weed pressure but it should be integrated with other weed control techniques. - Hairy vetch showed poor establishment because of the combination of scarce emergence due to sod-seeding and low temperatures. - Italian ryegrass was more tolerant to low temperatures and showed a good cover that contained weed growth. - Cover crop mixture showed variable results with higher suppression probably related to the number of cover crop species present in the mixture. - The termination methods (crimping and shredding) did not affect weed density and rice yield.

Cover crops can determine positive benefits on soil fertility and rice productivity, although scant attention has been devoted to evaluating the effects of hairy vetch (Vicia villosa Roth) and the incorporation of rice straw with different N fertilization levels on soil N and P availability and crop yields in temperate cropping systems characterized by poorly developed soils. In this study, the effects of cover crops grown before rice in a temperate mono-cropping system (NW Italy) on: (i) crop yields and yield components; (ii) apparent N fertilizer recovery and optimal level of N fertilization with hairy vetch; and (iii) temporal variation of soil available N and P forms during the hairy vetch growth and rice cropping season, have been investigated. The cultivation and incorporation of hairy vetch in the rice cropping system increased grain productivity by 12%, while reducing N mineral fertilization requirements by 33%. Combined with the incorporation of crop residues, hairy vetch provided a N and P input of 178 and 18 kg ha−1, respectively, representing a readily available source for plant uptake over the whole rice cropping season, particularly under anaerobic conditions. This results in a better temporal synchronization of soil N and P availability with crop nutrient demand, leading to a better rice grain productivity and quality performance.

Agriculture contributes to over 20% of global anthropogenic GHG emissions and irrigated paddy fields account for 5–10% of CH4 emissions. Main organic input providing methanogenesis substrate is straw. We hypothesized that removing rice straw can mitigate CH4 emissions, and that replacing its carbon (C) input with raw or solid digestate can be a valuable alternative both for crop, soil and emission responses. A mesocosm study was setup to follow crop growth, changes in soil pore water chemistry (dissolved Fe(II) and dissolved Organic C), and CH4 emissions over one cropping season on soil treated with the combination of two straw managements (removal or incorporation) and three fertilizations (mineral, raw digestate, solid digestate). Soils not receiving straw on average emitted 38 % less than soils after straw incorporation, while the two organic fertilizers did not increase emissions with respect to mineral N application. Furthermore, straw incorporation induced a yield depression independently from the fertilization strategy, probably as a result of N immobilization, especially in early stages. This was evidenced by early SPAD observations and flag leaf length, and both grain and straw final production. Moreover, the two organic fertilizers were not fully able to sustain crop N requirements with respect to the mineral fertilizer. Straw management was therefore decisive for determining both rice yield and CH4 emissions, while the impact of fertilization treatments was crucial only for crop productivity.

Many excellent results are obtained in agricultural and forestry research projects, but their practical adoption is often limited. The aim of the European project VALERIE is to increase the transfer and application of innovations produced by research in agriculture and forestry, by facilitating their integration into management practices. The project is still ongoing and the results illustrated in this paper are still temporary and subject to being improved. Here we present the methodology used in VALERIE to extract and summarise knowledge for innovation from research documents with the aim of making it available to final users through ask-Valerie.eu; we also report on current progress. The tasks associated with extracting and summarising knowledge are centred on: i) an ontology; ii) a document base; and iii) a system (ask-Valerie.eu) that allows users to effectively search the document base. An ontology defines a set of concepts and the relations between them. The VALERIE ontology is built by experts in the agricultural and forestry domain and contains 6169 concepts (21st October 2016). The document base is the collection of documents in which the system searches. The VALERIE document base includes scientific and practical documents derived from various sources, written in any of a number of languages. All documents contained in the document base are annotated using the ontology: each term (a word or a short phrase) in the document that matches a concept in the VALERIE-ontology is linked to that concept. Annotation is an automated process that takes place whenever a document is added to the document base. The document base contains 4278 documents (October 2016). Among them, there are 201 minifactsheets written by members of the VALERIE project, each describing an innovation with: a short description of the innovation, a list of correlated projects, and some links to scientific and practical documents. ask-Valerie.eu searches documents and fragments of text from the document base that address the user’s query. ask-Valerie.eu mimics the dialogue between a practitioner and an expert and achieves this functionality by: i) supporting the practitioner in articulating the question (it completes terms that the user starts to type and suggests other possibly relevant terms); ii) expanding the query using synonyms; iii) extracting and ranking text fragments from the documents.