E. Bonari

Variation in agronomic characteristics and seed oil composition of new oilseed crops in central Italy

The following new potential oilseed crops for industrial uses have been considered for agronomic traits and seed oil composition during a 3 year trial in Central Italy: Calendula officinalis (calendic acid); Camelina sativa and Lepidium sativum (linolenic acid); Coriandrum sativum (petroselinic acid); Euphorbia lagascae and Vernonia galamensis (epoxy fatty acids); Madia sativa (linoleic acid); Lesquerella fendleri (hydroxy fatty acids). Agronomic characteristics were examined in replicated field trials and phenological and morphological assessments were made. Seed oil content was determined by the Soxhlet method. Fatty acids were determined by gas liquid chromatography after transesterification to the methyl esters. A range of variation within most species was established for genetic differences in such traits as date of flowering, plant height, seed yield and oil percentage. Mean oil content in Camelina sativa, Lepidium sativum, Madia sativa and Coriandrum sativum was also influenced by the climatic conditions occurring in the different years, decreasing in the driest seasons. Some species (Coriandrum sativum, Madia sativa, Vernonia galamensis, Euphorbia lagascae and Lesquerella fendleri) produced high levels (more than 50%) of a single fatty acid in their seeds. This finding is favourable for industrial uses by minimising dowstream processing costs. On the other hand, other species (Lepidium sativum, Camelina sativa, Calendula officinalis) contained a mixture of fatty acids in their seeds. Some of these species showed good agronomic traits, including tolerance to drought and to high temperature, making them potentially suitable for cultivation in the Mediterranean area. For most of them, further breeding work should be directed towards increasing seed oil content and eliminating certain wild characteristics such as fruit dehiscence.

Biomass production and energy balance of a 12-year-old short-rotation coppice poplar stand under different cutting cycles

Given todays political targets, energy production from agricultural areas is likely to increase and therefore needs to be more sustainable. The aim of this study was thus to carry out a long‐term field trial based on the poplar short‐rotation coppice (SRC), in order to compare dry matter, energy‐use efficiency and the net energy yield obtainable from this crop in relation to different harvest frequencies (1‐, 2‐ and 3‐year cutting cycles). The results showed that poplar SRC performed very well under temperate climates as it can survive up to 12 years, providing a considerable annual biomass yield (9.9, 13.8, 16.4 t ha−1 yr−1 for annual T1, biannual T2 and triennial T3 cutting cycles, respectively). The system tested in southern Europe showed a positive energy balance characterized by a high energy efficiency. We found that the choice of harvest interval had huge consequences in terms of energy yields. In fact, the energy efficiency improved from T1 to T2 and T3, while the net energy yield increased from 172 to 299 GJ ha−1 yr−1. This study suggests that, with 3‐year harvest cycles, poplar SRC can contribute to agronomic and environmental sustainability not only in terms of its high yield and energy efficiency but also in terms of its positive influence on limiting soil tillage and on the environment, given its low pesticide and nutrient requirements.

Landscape agronomy: a new field for addressing agricultural landscape dynamics

Landscape dynamics increasingly challenge agronomists to explain how and why agricultural landscapes are designed and managed by farmers. Nevertheless, agronomy is rarely included in the wide range of disciplines involved in landscape research. In this paper, we describe how landscape agronomy can help explain the relationship between farming systems and agricultural landscape dynamics. For this, we propose a conceptual model of agricultural landscape dynamics that illustrates the specific contribution of agronomy to landscape research. This model describes the relationship between three elements: farming practices, landscape patterns and natural resources. It can stimulate agronomists to deal with research issues in agricultural landscape dynamics and enhance the interdisciplinary integration of farming systems in wider landscape research. On these premises, we discuss the main research issues that will benefit from an active involvement of agronomy, to understand, but also to assess landscape dynamics and to design relevant decision support systems.

Establishment, persistence and effectiveness of arbuscular mycorrhizal fungal inoculants in the field revealed using molecular genetic tracing and measurement of yield components

• Inoculation of crop plants by non-native strains of arbuscular mycorrhizal (AM) fungi as bio-enhancers is promoted without clear evidence for symbiotic effectiveness and fungal persistence. To address such gaps, the forage legume Medicago sativa was inoculated in an agronomic field trial with two isolates of Funneliformis mosseae differing in their nuclear rDNA sequences from native strains. • The inoculants were traced by PCR with a novel combination of the universal fungal NS31 and Glomeromycota-specific LSUGlom1 primers which target the nuclear rDNA cistron. The amplicons were classified by restriction fragment length polymorphism and sequencing. • The two applied fungal inoculants were successfully traced and discriminated from native strains in roots sampled from the field up to 2 yr post inoculation. Moreover, field inoculation with inocula of non-native isolates of F. mosseae appeared to have stimulated root colonization and yield of M. sativa. • Proof of inoculation success and sustained positive effects on biomass production and quality of M. sativa crop plants hold promise for the role that AM fungal inoculants could play in agriculture.

Suitability of giant reed (Arundo donax L.) for anaerobic digestion: Effect of harvest time and frequency on the biomethane yield potential

This study aimed to investigate the potential of giant reed for biomethane production by examining the influence of harvest time and frequency on the Biochemical Methane Potential (BMP), the kinetics of biomethane accumulation in batch reactors and the expected methane yield per hectare. The crop was cut at five different times, regrowths from early cuts were harvested in autumn and BMP of each cut was assessed. The highest BMP (392 NL kg VS(-1)) and the best kinetics of methane production were associated to juvenile traits of the crop. By coupling the early cuts with the corresponding regrowths (double harvest), the dry biomass (from 35 to 40 Mg ha(-1)) equaled that obtained by a single cut at end of the season (38 Mg ha(-1)), while the methane yield per hectare (11,585-12,981 Nm(3) ha(-1)) exceeded up to 35% the methane produced with a single harvest at crop maturity (9452 Nm(3) ha(-1)).

Evapotranspiration, crop coefficient and water use efficiency of giant reed (Arundo donax L.) and miscanthus (Miscanthus × giganteus Greef et Deu.) in a Mediterranean environment.

Giant reed (Arundo donax L.) and miscanthus (Miscanthus × giganteus Greef et Deu.) are two perennial rhizomatous grasses (PRGs), considered as promising sources of lignocellulosic biomass for renewable energy production. Although the agronomic performance of these species has been addressed by several studies, the literature dedicated to the crop water use of giant reed and miscanthus is still limited. Our objective was thus to investigate giant reed and miscanthus water use by assessing crop evapotranspiration (ETc), crop coefficients (Kc) and water use efficiency (WUE). The study was carried out in central Italy and specifically designed water‐balance lysimeters were used to investigate the water use of these PRGs during the 2010 and 2011 growing seasons. Giant reed showed the highest cumulative evapotranspiration, with an average consumption of approximately 1100 mm, nearly 20% higher than miscanthus (900 mm). Crop evapotranspiration rates differed significantly between the species, particularly during the midseason (from June to September), when average daily ETc was 7.4 and 6.2 mm in giant reed and miscanthus respectively. The Kc values determined in our study varied from 0.4 to 1.9 for giant reed and 0.3 to 1.6 for miscanthus. Finally, WUE was higher in miscanthus than in giant reed, with average values of 4.2 and 3.1 g L−1 respectively. Further studies concerning water use under nonoptimal water conditions should be carried out and an assessment of the response to water stress of both crops is necessary to integrate the findings from this study.

Effects of conventional and minimum tillage on winter oilseed rape (Brassica napus L.) in a sandy soil

Abstract A 3-year (1986–1988) comparison between conventional (CT) (25 cm deep ploughing) and minimum (MT) (10–15 cm deep disk harrowing) tillage was carried out in southwest Tuscany on a very sandy soil (Typic Xeropsamment) where oil rapeseed was cultivated. The CT plots showed a greater water retention capacity in the deeper horizons than the MT plots. Moreover CT was characterized by a quicker water rate of depletion in the upper soil layers when evapotranspirative demand was high. The bulk density and penetration resistance of the ploughed soil, measured to 30 cm depth, were less under CT than under MT. The presence of subsurface compacted soil layers as the result of continuous MT caused a progressive worsening of soil conditions for plant root growth and, consequently, a reduction of root system mass and tap-root length compared with the ploughed plots. However, rapeseed grain and biomass yields under CT and MT never differed significantly. Finally, MT use was connected with remarkable reductions (55% on average) of working time, fuel consumption, energy requirement and cost when compared with CT.

Soil Microbial Characteristics and Mineral Nitrogen Availability as Affected by Olive Oil Waste Water Applied to Cultivated Soil

Abstract Waste disposal is an urgent problem in those Italian areas devoted to olive oil production where a large amount of olive oil waste is produced in a short period of time. Given the high organic matter and macronutrient content of olive oil waste water, its use in agriculture could help to solve the disposal problem and, at the same time, to improve the physiochemical characteristics of intensely cultivated soils. However, olive oil waste water contains noteworthy quantities of phenols, which are toxic and have bacteriostatic activity. The effects of repeated spreading of olive oil waste water on alfalfa, on soil microbial properties, and on the availability of mineral nitrogen were determined. Doses of 0, 80, and 160 m3 ha−1 of olive oil waste water (OW) were spread over experimental plots sown with 3rd year alfalfa. Soil samples were collected at various intervals after OW application. The biomass, respiratory activity, metabolic quotient, mineralization index, and the potential nitrification activity (PNA) of the soil were measured. Polyphenol, organic carbon, and mineral nitrogen contents were measured on the same soil samples. In general, the spreading of OW caused slightly positive modifications to the soil microbial biomass and metabolic quotient. These modifications were temporary and disappeared as early as a few months after the treatment. The PNA, as well as the nitrate and nitrite contents, were lower in the treated plots during the vegetative cycle of alfalfa and after the last harvest, and appeared to be negatively correlated with polyphenols. The results of this experiment confirmed that the spreading of olive oil waste water on cultivated soil could be an eco‐compatible practice. Despite their origin, the OW had no toxic effects on the soil microflora, and in fact, stimulated growth and reproduction of cells. Only the PNA proved to be slightly reduced, but the yield was not negatively affected.

Hydrothermal Conversion of Giant Reed to Furfural and Levulinic Acid: Optimization of the Process under Microwave Irradiation and Investigation of Distinctive Agronomic Parameters

The hydrothermal conversion of giant reed (Arundo donax L.) to furfural (FA) and levulinic acid (LA) was investigated in the presence of dilute hydrochloric acid. FA and LA yields were improved by univariate optimization of the main reaction parameters: concentration of the acid catalyst, solid/liquid ratio of the reaction mixture, hydrolysis temperature, and reaction time. The catalytic performances were investigated adopting the efficient microwave (MW) irradiation, allowing significant energy and time savings. The best FA and LA yields were further confirmed using a traditionally heated autoclave reactor, giving very high results, when compared with the literature. Hydrolysis temperature and time were the main reaction variables to be carefully optimized: FA formation needed milder reaction conditions, while LA more severe ones. The effect of the crop management (e.g., harvest time) on FA/LA production was discussed, revealing that harvest time was not a discriminating parameter for the further optimization of both FA and LA production, due to the very high productivity of the giant reed throughout the year. The promising results demonstrate that giant reed represents a very interesting candidate for a very high contemporary production of FA and LA of up to about 70% and 90% of the theoretical yields, respectively.

Effects of tillage on porosity and microstructure of a loam soil

Abstract Changes in porosity, shape, size and length of pores and microstructure in a loam soil under different types of tillage were examined. A micromorphological method was used to evaluate soil structure, characterizing porosity in soil thin sections prepared from undisturbed soil samples by means of electro-optical image analysis (Quantimet 720). Results showed that both total porosity and number of pores in topsoil were not significantly different among the plots under different types of tillage. Below the topsoil (10–15 cm) in the plots tilled by a disc harrow porosity decreased substantially making for a massive structure. In the 25–30 cm layer porosity was not significantly different in plots ploughed to a depth of 25 cm than in those ploughed to a depth of 50 cm. In the chisel ploughed plots porosity seemed to be more homogeneously distributed along the Ap horizon. Modifications in pore shape, size distribution and length and in microstructure were also observed. Surface crusts formed frequently in ploughed plots.