The conversion from conventional tillage (CT) to no-tillage (NT) of the soil is often suggested for positive long-term effects on several physical and hydraulic soil properties. In fact, although shortly after the conversion a worsening of the soil may occur, this transition should evolve in a progressive improvement of soil properties. Therefore, investigations aiming at evaluating the effects of NT on porous media are advisable, since such information may be relevant to better address the farmers’ choices to this specific soil conservation management strategy. In this investigation, innovative and standard methods were applied to compare CT and NT on two farms where the conversion took place 6 or 24 years ago, respectively. Regardless of the investigated farm, results showed negligible differences in cumulative infiltration or infiltration rate, soil sorptivity, saturated hydraulic conductivity, conductive pores size, or hydraulic conductivity functions. Since relatively small discrepancies were also highlighted in terms of bulk density or soil organic carbon, it was possible to conclude that NT did not have a negative impact on the main physical and hydraulic properties of investigated clay soils. However, a significantly higher number of small pores was detected under long-term NT compared to CT, so we concluded that the former soil was a more conductive pore system, i.e., consisting of numerous relatively smaller pores but continuous and better interconnected. Based on measured capacity-based indicators (macroporosity, air capacity, relative field capacity, plant available water capacity), NT always showed a more appropriate proportion of water and air in the soil.
To assess spatial variability at the very fine scale required by Precision Agriculture, different proximal and remote sensors have been used. They provide large amounts and different types of data which need to be combined. An integrated approach, using multivariate geostatistical data-fusion techniques and multi-source geophysical sensor data to determine simple summary scale-dependent indices, is described here. These indices can be used to delineate management zones to be submitted to differential management. Such a data fusion approach with geophysical sensors was applied in a soil of an agronomic field cropped with tomato. The synthetic regionalized factors determined, contributed to split the 3D edaphic environment into two main horizontal structures with different hydraulic properties and to disclose two main horizons in the 0–1.0-m depth with a discontinuity probably occurring between 0.40 m and 0.70 m. Comparing this partition with the soil properties measured with a shallow sampling, it was possible to verify the coherence in the topsoil between the dielectric properties and other properties more directly related to agronomic management. These results confirm the advantages of using proximal sensing as a preliminary step in the application of site-specific management. Combining disparate spatial data (data fusion) is not at all a naive problem and novel and powerful methods need to be developed.
A three-year field experiment was conducted in a Mediterranean environment on lettuce to study the production, characteristics and possible use of different amendments as substitution for nitrogen mineral fertilizers. The effects on soil dynamics were also investigated. The following treatments supplying 140 kg N ha−1 were compared: Stabilized anaerobic digestate from wine distillery wastewater (SAD); Non-stabilized organic material from wine distillery wastewater (NSAD); Olive pomace compost (OPC); Mineral N fertilizer (MIN); Commercial organic fertilizer (CORG). These treatments were compared with an unfertilized control (CONTR). No significant reduction occurred with SAD as compared to MIN, but its application significantly increased marketable yield in all experimental years compared to the unfertilized control. Furthermore, SAD treatment reached the highest marketable yield with an increase of 52.9% compared to CONTR in the year characterized by high unevenly rainfall distribution. Even with low absolute values, the application of mineral fertilizer not only had the highest level of nitrate in the leaves but also determined higher value of soil mineral N compared to by-products treatments, thereby increasing pollution risks. The NSAD and the OPC treatments had significantly lower biomass and marketable yield than MIN and presented the highest soil N mineral deficit. As a consequence, the choice and the production of the more appropriate agroindustrial by-product (in our research SAD treatment) is crucial to ensure lettuce yield and the sustainability of agro-ecosystem.
Alternaria alternata and Alternaria radicina are fungal species that occur in several food crops and may produce mycotoxins and phytotoxins. The toxigenic profile of A. alternata and A. radicina isolated from carrot and other umbelliferous plants was determined by growing the fungus on rice and carrot discs. Most of the tested isolates of A. alternata produced the mycotoxins tenuazonic acid, alternariol, alternariol methyl ether and altertoxin–I on rice. Only alternariol and alternariol methyl ether were produced on carrot discs. When cultured on rice, none of the isolates of A. alternata from umbelliferous plants produced AAL toxins and fumonisins. AAL toxins, but not fumonisins, were instead produced by A. alternata f. sp. lycopersici isolate NRRL 18822 isolated from tomato. A. radicina produced the phytotoxic compounds radicinin, epi–radicinol and radicinol on carrot discs, whereas it produced radicinin and radicinol on rice. Although A. alternata has been frequently found in organic carrots, none of the above mycotoxins was detected in carrot roots or in carrot commercial products. The reduction of alternariol and alternariol methyl ether during carrot juice processing at laboratory scale was estimated to be >98%. Based on these findings and previous reports, it can be concluded that Alternaria mycotoxins in carrots do not represent a hazard for consumers.