FLUXES OF NITROGEN WITHIN DECIDUOUS FRUIT TREES

Nitrogen (N) nutrition is a major means of controlling growth and fruiting of trees. In EU Countries, society’s expectations and political decisions have pushed for the adoption of sustainable ways to manage orchards. Guidelines for N management aim to limit fertiliser applications under threshold limits, in order to reduce N losses. Increasing the effectiveness of the recycling of the N present in the orchard is a basic step to reduce external N inputs. The availability of the stable isotope 15N as experimental tool has made possible significant advances in the knowledge of the fluxes of N at tree and orchardlevel. This paper discusses the N fluxes occurring within the tree both between the years and within the year (root-shoot-root N recycle) and their role in the vegetative and reproductive cycle of fruit trees

Contribution of cauliflower residues to N nutrition of subsequent lettuce crops grown in rotation in an Italian Alpine environment

Up to 75% of nitrogen (N) taken up during cauliflowers production is allocated to leaves, which are left as crop residues after harvest. The inclusion of cauliflower, cultivated alone or intercropped with legumes, in rotation schemes, is a promising tool to optimize N availability to subsequent crops. This original study assessed, for the first time in South Tyrol, Italy, the effect of removal or soil incorporation of cauliflower and clover residues on the growth and N uptake of subsequent lettuce. In 2015, cauliflower was sole-cropped or intercropped with clover, under different N regimes (N0, N1, N2, N3 = 0, 75, 150, 300 kg N ha−1). Cauliflower and clover residues were either removed or incorporated in the soil in 2016. The effects of the residual fertility left by the N fertilizer, the two cropping systems, and the crop residues were assessed on the yield and N uptake of two subsequent lettuce crops. Isotopic 15Nlabeled cauliflower residues were additionally used to quantify the N contribution of cauliflower residues to lettuce growth. During the first lettuce crop, residues incorporation was the only factor increasing lettuce yields (+41%) and N uptake (+58%). The residual effect of N1 and N2 rates increased the lettuce N uptake when clover residues were incorporated. During the second lettuce crop, residues incorporation increased lettuce yields (+26%) and N uptake (+44%). On average, 64% and 35% of the lettuce N amounts, in the first and second cycles, respectively, derived from cauliflower residues, and accounted for 38% of the total N contained in cauliflower residues (214 kg N ha−1). Results from this experiment, uncommon for the examined species, demonstrate that incorporation of cauliflower and clover residues provides an excellent source of N for lettuce. Incorporating residues of the preceding cauliflower crop, alone or intercropped with clover, before establishing the lettuce crop, substantially reduce the N fertilization needs of subsequent lettuce crops

A Review

Abstract This review is based partly on complete articles and partly on abstracts. Three of the 60 articles deal with the total uptake of elements in strawberry plant organs in two different strawberry production systems, both considered as optimal concerning amount and balance of elements. The effect on fruit quality may be dramatic if the level of a particular element is outside this range, but there may also be effects initiated by differences within the optimal range of elements. Most articles refer to product oriented quality, but some focus on consumer oriented quality, as discussed by Shewfelt (1999). The discussion here is on a general basis, so one should keep in mind that there are cultivar differences and that specification of nutrition ideally should mirror the needs of a single cultivar, or a group of cultivars with similar requirements. Also, to get a complete understanding of the subject future reviews should embrace a broader access of information including the effect on plant development ..

Chemical and biological indicators of water quality in three agricultural watersheds of the Po valley, Italy

open9noAgriculture has both direct and indirect effects on quality of surface water and is one of the key activities causing water quality degradation. Its environmental impact can be evaluated by the determination of indicators of the quality of water bodies that collect drainage and runoff waters from agricultural watersheds. For this research, the water quality draining from three watersheds, totally or partially cultivated, all within the Po river valley (Italy), was determined, using chemical indicators (N-NO3 and N-NH4 concentration, N balance), trophic status (chlorophyll-a concentration) and benthic population indexes. Together, they should provide an overview of the water status, which is supposed to be strictly related to the land use and the management. Results show that the chemical parameters are well related to land use and farming management: intensive agricultural activity leads to high N-NO3 concentration in water and N surplus and vice versa. The chlorophyll-a concentration follows the same trend, being linked to nitrogen loads and land use. Not always there is accordance between chemical and biological indicators: no direct correspondence is evident between the N-NO3 concentration in waters and benthic community. Its presence and abundance seems to be mostly correlated with the geomorphology, hydrology, riparian strips, etc. of the habitat than to the land use. Only the integration of chemical and biological parameters allows a correct understanding of the state of health of water body and benthic communities.openPIERI L.; VENTURA F.; VENTURA M.; TAGLIAVINI M.; PONTI M.; PISTOCCHI R.; ALBERTAZZI S.; VIGNUDELLI M.; ROSSI PISA P.PIERI L.; VENTURA F.; VENTURA M.; TAGLIAVINI M.; PONTI M.; PISTOCCHI R.; ALBERTAZZI S.; VIGNUDELLI M.; ROSSI PISA P

Understanding carbon sequestration, allocation, and ecosystem storage in a grassed vineyard

Understanding if and to which extent a crop can act as a carbon sink is the basis of the assessment of its sustainability in the climate change context. Grassed vineyards have been indicated in the recent past as potentially large carbon sinks, questioning the assumption that crops are in general carbon sources. To this end, we conducted a detailed study along a growing season in a grassed mountain vineyard with two varieties (Chardonnay and Sauvignon blanc) to quantify the overall carbon stock of the system and to attribute the carbon fluxes to the specific components of the carbon cycle of the agroecosystem, including vines organs (shoots, fruits, roots), grasses (shoots and roots) and soil. We combined eddy covariance, soil respiration, biometric measurements, and soil analysis. Our findings determined the studied vineyard to be a moderate carbon sink. We found a gross primary production (2409 ± 35 g C m-2) much larger than previous data for vineyards, but the NEP (246 ± 54 g C m-2) of the growing season was on the lower end of previous reports. Based on similar above-ground net primary production values for the grapevines and herbaceous vegetation, we confirmed that the grassed alleys play an important role in overall carbon accumulation. We also observed that the soil represents by far the largest carbon storage, being the carbon retained by vegetation at harvest time only 7.3% of the total. The overall carbon stored in the vineyard (152.1 ± 7.1 t C ha-1) was less than that of forests and some orchards primarily due to the lower amount of plant biomass. Permanent grassland sites generally contained much higher amounts of carbon in the topsoil, indicating that there are vineyard characteristics or management practices which limit long term storage in this pool. Further studies are needed to unravel the relative contribution of the grapevines and grasses to overall gross primary productivity and carbon storage potential, especially in the context of different management decisions and the increasing frequency of drought events in similar mountain environments.Fil: Callesen Torben, Oliver. University of Bozen-Bolzano; ItaliaFil: Gonzalez, Carina Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Biología Agrícola de Mendoza. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Instituto de Biología Agrícola de Mendoza; ArgentinaFil: Bastos Campos, Flavio. University of Bozen-Bolzano; ItaliaFil: Zanotelli, Damiano. University of Bozen-Bolzano; ItaliaFil: Tagliavini, Massimo. University of Bozen-Bolzano; ItaliaFil: Montagnani. Leonardo. University of Bozen-Bolzano; Itali

How do geomorphic characteristics affect the source of tree water uptake in restored river floodplains?

Alpine rivers and their floodplains have been highly modified by human activities during the last decades. River restoration projects aim to counteract these negative impacts and to restore ecosystem services provided by riparian habitats. We studied two recently restored river sites in the Ahr/Aurino and Mareit/Mareta Rivers (Italian Alps) to investigate how geomorphic conditions, soil moisture, and groundwater level affect the source of water used by grey alder (Alnus incana (L.) Moench). We compared the isotopic composition (δ2H) of tree sap at different locations (low terraces formed during bed incision and recent floodplains formed after restoration) with that of potential water sources, that is, groundwater, soil water, and rainfall. The monthly variation in the isotopic composition of rainfall was reflected in both shallow and deeper soil water, as well as in the isotopic composition of sap. The redistribution of precipitation and groundwater in the soil differed between the post-restoration floodplain sites and the post-incision terraces, leading to a different relation between the sap water, soil water, and groundwater isotopic composition. The results show that transpiration of A. incana trees growing on recent floodplains is mostly supported by stream-fed soil water, whereas trees growing on terraces mainly use precipitation-fed soil water. These marked, morphology-related differences in the source of transpiration water of grey alder highlight how channel degradation still affects the ecohydrological processes in Alpine fluvial corridors. Nonetheless, large restoration interventions—in terms of channel widening—can enable the self-formation of new floodplain areas characterized by stream water-fed riparian ecosystems

Evapotranspiration Dynamics and Partitioning in a Grassed Vineyard: Ecophysiological and Computational Modeling Approaches

Plenty of information on evapotranspiration (ET) dynamics and partitioning into nonbiological (evaporation, E) and biological (transpiration, T) components is available in literature. However, in agro-ecosystems where more than one vegetation group is found, like intercropping or grassed orchards and vineyards, it is of great use to understand the contribution to T due to the single plant type or group of plants. We deployed empirical and modeling methods to study the ecosystem evapotranspiration (ETEC) components in a grassed vineyard in Caldaro (Italy) aiming to assess (a) which process, E or T, had greater influence on ETEC dynamics; (b) which component among grapevines and understorey portion dominated the ETEC; and (c) how rainfall influences ETEC components. A top-down approach combined the eddy covariance method to estimate ETEC, and the Transpiration Estimation Algorithm method to partition it. A bottom-up approach integrated the understorey evapotranspiration (ETu) with modeled vines transpiration (Tv((mod))). Measured and modeled fluxes showed high daily variability, consistently with meteorological conditions (vapor pressure deficit, Rn and Tair). The mean daily ETEC integrals were 3.45 and 3.40 mm d(-1) (2021 and 2022), being T-EC (estimated transpiration fraction of ETEC) the higher contributor (T-EC/ETEC of 0.77 and 0.79, same years). From the bottom-up approach, ETu assessed during ground flux chamber campaigns (0.74-1.65 mm d(-1)) was lower than Tv((mod)). A high agreement (R-2 = 0.85) was found between the eddy covariance ET hourly values and ET by summing Tv((mod)) and ETu. We concluded that the T process represented major fluxes in the agroecosystem during the warm season. Furthermore, the bottom-up approach indicated the vines as primary contributors to ecosystem T, particularly noticeable after rainfall, as the understorey T fraction (Tu) increased when the system became drier. This study helps disentangling grapevine contribution to evapotranspiration from adjacent herbaceous vegetation in a vineyard, and emphasizes the dominance of biologically mediated transpiration influenced by meteorological conditions. This novel combination of approaches not only enhances understanding of Mediterranean viticulture but also illuminates broader applications in sparsely vegetated environments, such as agroforestry systems and orchards, advancing ecological management practices