Long Term Amendment with Fresh and Composted Solid Olive Mill Waste on Olive Grove Affects Carbon Sequestration by Prunings, Fruits, and Soil

Abstract

The soil amendment with organic wastes represents a way to increase the soil fertility and the organic carbon (C) stored in the agro-ecosystems. Among the organic waste materials produced by agricultural and industrial activities, olive mill wastes derived from the olive oil extraction process may represent a suitable soil amendment. The aim of the study was to evaluate the effect of fresh (SOMW) or composted mixture of SOMW and shredded olive tree prunings (C-SOMW+P) on the vegetative and productive activities of olive trees, on the C stored in the tree non-permanent structures (prunings and fruits) and in the soil. The plots treated with SOMW or C-SOMW+P showed higher vegetative and productive activities than the untreated plots, and this was attributed to the higher total N and availability of P and K supplied by the amendments. Consequently, treatments increased the C sequestered in the tree non-permanent structures than in the control trees. However, no significant different effect between SOMW and C-SOMW+P treatments was found for the C stored in prunings and fruits, whereas it was evident a stronger influence of C-SOMW+P than SOMW on soil C sequestration. Indeed, about 50% the C supplied by the treatment with C-SOMW+P was sequestered in the olive grove system, with more than 90% of the sequestered C stored into the soil. The low amount of C sequestered in the soil following the addition of SOMW was attributed to its richness of moisture and easily degradable compounds that triggered the mineralization processes controlled by the soil microbial community. Although the 8 years of amendment produced a higher fruit yields than the control, no difference occurred between the characteristics and the oil content of the olive fruits. Only the total phenol content for the oil obtained from the SOMW-treated plots was significantly higher. The other considered fruit characteristics did not show significant differences.

The use of gamma radiation for extractability improvement of bioactive compounds in olive oil wastes

“…In Portugal, this industry produces N600,000 t of wastes, whose discharge without treatment would have a negative impact in the environment. Due to the high content in phosphorous, potassium and organic matter, these wastes have been applied as amendment on the agricultural soils, not only because of its low cost but also for its potential to enhance soil fertility and reduce the risks of soil degradation (Federici et al, 2017;Regni et al, 2017). On the other hand, these wastes contain high amounts of organic substances (fibers, sugars, volatile fatty acids, polyalcohols, pectins and fats) and a variety of phenolic compounds such as hydroxytyrosol and tyrosol, secoiridoid derivatives, phenolic acids and flavonoids (Papaioannou et al, 2013), thus being also a promising source of valuable compounds.…”

Co-composting of Olive Mill Waste and Wine-Processing Waste: An Application of Compost as Soil Amendment

“…e different residues from the wine industry are characterized by low pH and electrical conductivity and high organic matter content [7]. e richness of these by-products in organic matter allows their use for soil fertility improvement [8,9]. e direct incorporation of these residues could cause serious environmental problems if they are added excessively to the soil in an uncontrolled manner.…”

“…Recently, researchers have shown that composting is one of the effective alternatives for the recycling and the valorization of organic wastes [8,[17][18][19][20][21][22]. It is a degradation process of the organic matter, allowing the achievement of a stable product, rich in humic substances and in fertilizing elements, serving as soil organic amendment [23][24][25].…”

“…It is a degradation process of the organic matter, allowing the achievement of a stable product, rich in humic substances and in fertilizing elements, serving as soil organic amendment [23][24][25]. e application of compost can have strong ecological environmental values, allowing not only the removal of very expensive chemical fertilizers but also the improvement of the quality of agricultural soils and carbon sequestration [8,9,26].…”

Recent Achievements and New Research Opportunities for Optimizing Macronutrient Availability, Acquisition, and Distribution for Perennial Fruit Crops

“…Inter-row cover cropping, retention of on-farm sources of organic matter (e.g., prunings), and application of off-farm sources of organic matter (e.g., composts and organic mulches) all can potentially increase soil organic carbon (SOC) stocks in perennial fruit cropping systems [19,20]. For example, amendments with olive mill waste have been reported to improve carbon sequestration in soils and improved N, P, and K availability in olive groves [21]. The use of fescue (Festuca arundinacea Schreb) has been reported to increase soil organic carbon and microbial biomass C in grapes [22].…”