Search

In order to best nutrient use efficiency, as required by the increasing food demand for the future global population, in this work an innovative hybrid nanocomposite was designed as an alternative nanoscale fertilizer. An environmentally friendly chemical preparation based on polyelectrolyte complexation was used. A chitosan and sodium alginate complex was selected as a biodegradable shell to release the nanoscale nutrient, CuO nanoparticles. By optimizing the synthesis conditions, i.e. pH and polymer/cross-linker ratio, good stability and accurate size control of the resulting nanocomposites were achieved. The morphology features were evaluated using scanning and transmission electron microscopy, and chemical characterization was performed using X-ray diffraction, thermogravimetric analysis, Fourier-transform infrared spectroscopy, dynamic light scattering and inductively coupled plasma optical emission spectrometry. All the collected data confirmed spontaneous polymeric aggregation in nanostructures of sperical shape, having a mean diameter of about 300 nm, as well as CuO encapsulation inside the polymeric coating. Moreover, the role of the biopolymer shell in the significant slowing of copper release from the hybrid nanocomposite was reported. Finally, the nanocomposite efficacy in seeding and germination was evaluated on Fortunella margarita Swingle seeds. The tests demonstrated the benefits in the seedling growth together with a synergic effect in developing both the epigean and hypogean parts. The obtained results indicated that the proposed hybrid nanocomposite could be a potential alternative to realize a smart delivery nanofertilizer using an eco-sustainable method.

(1) Background: The commercial sustainability of the citrus nursery industry involves cutting costs by using alternative planting substrates to replace (or partially replace) the conventional black peat. Conifer wood biochar was evaluated as a component of the growth medium in a commercial citrus nursery for Carrizo citrange seedlings. (2) Methods: Seven growth media mixtures (A&ndash, G) were tested. Each mixture consisted of 50% sandy volcanic soil with the remaining 50% made up as follows: A = black peat and perlite 1:1, B = biochar 1, C = black peat, perlite, and biochar 0.5:1:0.5, D = black peat and biochar 1:1, E = black peat, compost, and biochar 0.5:0.5:1, F = black peat, perlite, compost, and biochar 0.5:0.5:0.5:0.5, G = black peat and lapillus 1:1, this substrate, previously adopted by the hosting nursery, was the control. (3) Results: The best media for the rootstock studied here were those containing 25% biochar (mixtures D and E). In the deeper layers the substrate was more compact, and the roots were limited to the shallow layers of the pot. (4) Conclusions: Conifer wood biochar can be partly added in place of peat in growth media mixtures, thus reducing costs and ameliorating sustainability.

We investigated long-term (18 years) effects of three organic (cow manure (CM), poultry manure (PM), compost from agro-industry orange wastes (OW)) and one inorganic fertilization (IF) on various soil biological indicators (microbial biomass C, soil respiration, total phospholipid fatty acids (PLFAs), total bacteria, Gram-positive and Gram-negative bacteria and fungi) and nutrient contents (total and extractable organic C, total and mineral N, available P and K) along the profile of a Typic Haplustept under orange Mediterranean orchards. All fertilizers were added on the same N content basis (190 kg N ha−1 per year). Variables related to carbon cycling gradually worsened with depth, regardless of treatment, but at any soil depth they improved according to IF < PM < OW < CM. Similarly, mineral nutrient availability decreased with increasing soil depth, according to CM > OW > PM > IF. Organic manures favoured Gram-negative bacteria, especially between 35 and 55 cm depth, whereas Gram-positive bacteria flourished better under inorganic fertilization up to 55 cm. Organic fertilizers increased microbial biomass C, compared with IF, with CM being the most efficient, i.e. inducing the greatest C use efficiency, in turn coupled with a greater amount of fungi compared to bacteria. This is crucial from the environmental viewpoint, since fungi better contribute to soil C storage. PLFAs signatures of microbial communities reflected the differences in resources availability determined by soil depth and fertilizer type; indeed, fungi and Gram-negative bacteria responded more promptly to nutrient contents than other microbial groups. Oligotrophic conditions in deeper soil horizons increased the metabolic quotient, an indicator of stress conditions.

The aim of the present paper was to investigate the agronomical responses of a fertilizer able to release nutrients on the basis of plant-demand, glass-matrix based fertilizer (GMF). Nutrient release was stimulated by mixing the glass-matrix with organic components such as digested vine vinasse (DVV) or meat-meal (MM), added with the aim to increase GMF biological affinity toward roots. Laboratory tests and short-term pots trials showed that the mixture GMF+DVV increased nutrient availability and plant growth. In the following stage these mixtures were tested for their ability to contrast in calcareous soils citrus iron chlorosis, one of major abiotic stresses affecting fruit tree crops in the Mediterranean area. Three year studies were conducted: i) in pots, on ‘Tarocco ScirA¨â€™ orange trees [Citrus sinensis (L.) Osbeck] grafted on Swingle citrumelo and ii) in field, on Tarocco grafted on sour orange rootstock [C. aurantium (L.) Osbeck], by comparing GMF and its mixtures with DVV and MM to a synthetic Fe chelate application. The GMF+DVV mixture was able to supply adequately micronutrients, particularly iron, reducing the chlorosis symptoms, increasing the leaf SPAD index and Fe concentration, and decreasing the "Fe index".

Several citrus orchards develop symptoms of Fe deficiency when cultivated in calcareous and alkaline soils. In a field trial a new type of fertilizer, the glass-matrix based fertilizer (GMF, a by-product from ceramic industries) was applied. GMF is able to release nutrients, particularly Fe, on the basis of plant-demand, being nutrients not soluble in water, but only in acidic or metal complexing solutions. In our experiment, the effectiveness of GMF was tested on “Tarocco” orange trees of twenty years, severely suffering from Fe chlorosis, also by mixing GMF with meat meal (MM) or digested vine vinasse (DVV), thus comparing these treatments to the conventional Fe-chelate fertilization and the Fe-unfertilized control. The GMF + DVV mixture showed to be able to supply adequately micronutrients (particularly Fe) on long term, reducing the chlorosis symptoms, increasing the leaf SPAD index, Fe concentration and decreasing Fe index. No significant effect on yield and fruit quality was noticed. Our results indicated that these innovative formulates, and in particular glass-matrix based fertilizer mixed with digested vine vinasse, could be used as an “environmental friendly” fertilizer, allowing not only to reduce the use of chemicals (such as Fe-chelate), but also to re-use industrial wastes and organic residues which gave an “adding value” to these novel organo-mineral formulates.

To investigate the influence of different types of fertilizers on quality parameters, N-containing compounds, and the δ15N, δ13C, δ2H, δ 34S, and δ18O values of citrus fruit, a study was performed on the orange fruit cv. ‘Valencia late’ (Citrus sinensis L. Osbeck), which was harvested in four plots (three organic and one conventional) located on the same farm. The results demonstrated that different types of organic fertilizers containing the same amount of nitrogen did not effect important changes in orange fruit quality parameters. The levels of total N and N-containing compounds such as synephrine in fruit juice were not statistically different among the different treatments. The δ15N values of orange fruit grown under fertilizer derived from animal origin as well as from vegetable compost were statistically higher than those grown with mineral fertilizer. Therefore, δ15N values can be used as an indicator of citrus fertilization management (organic or conventional), because even when applied organic f...

A 6-year study was conducted in an organically managed orange orchard located in Sicily (Southern Italy) to assess the effect of compost and organic fertiliser utilisation on soil quality. Adopting a randomised-block experimental design with three replicates, four treatments were carried out. In treatments 1 and 2, two different composts (C1 from distillery by-products and C2 from livestock waste) were applied. The plots of treatment 3 were fertilised using dried poultry manure. The control treatment was fertilised by mineral/synthetic fertilisers. In order to verify the hypothesis that composts and organic fertilisers improve soil fertility, soil quality was evaluated by selecting dynamic soil parameters, as indicators linked to C and N cycles. Total organic C, total N, C/N ratio, humified fraction, isoelectric focussing (IEF) of extracted organic matter, microbial biomass C, potentially mineralisable N under anaerobic conditions, potentially mineralisable C, C mineralisation quotient and metabolic quotient were determined for each sample. Moreover, the Community Level Physiological Profile (by Biolog technique) was defined, calculating derived functional biodiversity and versatility indexes. Parameters related to IEF and potentially mineralisable C showed significant differences among the treatments. Moreover, total C, total N and humification parameters tended to increase, while no differences were observed in biodiversity indexes. On these findings, it was concluded that composts and poultry manure only weakly affected soil properties, though they increased soil potentially available nutritive elements to crops.

In a study realised over a three year period on orange bearing trees (Citrus sinensis (L.) Osbeck) ‘Valencia late’, grafted on sour orange (C. aurantium L.), the effect of organic fertilisers (OF) on plant nutrition and performance was verified. In a randomized block experimental design, four treatments were compared, namely: mineral fertiliser (MF) treatment adopted as control, citrus byproduct compost (CB), poultry manure (PM) and livestock waste compost (LW). The trees, with the exception of (MF) treatment, were organically grown since 1994 in the experimental farm of CRA-ACM in Lentini, Sicily, and received the same N input every year. Significant differences for micronutrients (Fe, Mn, Zn) were noticed in leaf analyses, whereas no difference was found between treatments for leaf macronutrient content. The δ 15 N detected in leaves, proteins of pulp and amino acids of juice showed the lower level in MF, an intermediate value in CB and the highest level in animal derived fertilisers treatments (PM and LW). Fruit of the CB treatment showed values of total soluble solids and total acidity significantly lower than other treatments. Orange peel Chroma C* in CB and MF was higher than in PM and LW treatments. Discriminant analysis of the leaf and fruit analytical data set successfully separated treatments. First discriminant canonical function explains the 96,9% of the variability, with highly significant Wilks’ lambda. Cross validation classified correctly all MF and CB samples, whereas PM and LW in few cases were mixed up.