The potential of recycling wool residues as an amendment for enhancing the physical and hydraulic properties of a sandy loam soil

Climate change and global food demand in coming decades urge effective actions for more efficient uses of water and soil resources. This paper reports the preliminary findings of a study assessing the potential of sheep scoured wool residues (SWRs) as soil amendments to enhance the physical and hydraulic properties of a sandy loam soil under rain conditions. Methods: Two different SWRs were used: scoured residues (white wool, WW) and carbonized scoured residues (black wool, BW) at different SWRs/soil ratios (0.0, 0.5, 1.0 and 2.0%). Soil bulk density (BD), total porosity (TP), aggregates stability, aggregate size distribution, saturated hydraulic conductivity, and water retention properties were determined under rain conditions, in addition to rainwater balance (storage, percolation and runoff). Results: Both WW and BW, particularly at the high wool/soil ratio (2%), significantly reduced soil BD by 11.98% and 9.85%, respectively. Moreover, WW and BW increased TP by 16.45% and 13.57% and available water capacity by 6.5% and 18.1%, respectively. SWRs increased the formation of macro-aggregates and increased aggregate stability. The results of rainwater balance showed higher percolation percentages and less rainwater storage in the wool-treated soil. Conclusions: The increase in water percolation is in line with the increased total porosity and the higher saturated hydraulic conductivity of wool-treated soil. Despite the high capacity of absorbing water, SWRs affected the water movement of the soil more than its water retention

Retrieving soil moisture in rainfed and irrigated fields using Sentinel-2 observations and a modified OPTRAM approach

Abstract Surface soil water content plays an important role in driving the exchange of latent and sensible heat between the atmosphere and land surface through transpiration and evaporation processes, regulating key physiological processes affecting plants growth. Given the high impact of water scarcity on yields, and of irrigated agriculture on the overall withdrawal rate of freshwater, it is important to define models that help to improve water resources management for agricultural purposes, and to optimize rainfed crop yield. Recent advances in satellite-based remote sensing have led to valuable solutions to estimate soil water content based on microwave or optical/thermal-infrared data. This study aims at improving soil water content estimation at high spatial and temporal resolution, by means of the Optical Trapezoid Model (OPTRAM) driven by Copernicus Sentinel-2 data. Two different model variations were considered, based on linear and nonlinear parameters constraints, and validated against in situ soil water content measurements made with time domain reflectometry (TDR) on irrigated maize in central Italy and on rainfed maize and pasture in northern Italy. For the first site the non-linear model shows a better correlation between measured and estimated soil water content values (r = 0.80) compared to the linear model (r = 0.73). In both cases the modeled soil moisture tends to overestimate the measured values at medium to high water content level, while both models underestimate soil moisture at low water content level. Estimated versus measured normalized surface soil water for rainfed pasture plots from nonlinear OPTRAM parametrized based on irrigated maize parameterization (SIM1), and site-specific parametrization for rainfed pasture (SIM2), indicate that both models (SIM1 and SIM2) are comparable for rotational grazing pasture (RMSEsim1 = 0.0581 vs. RMSEsim2 = 0.0485 cm3 cm-3) and the continuous grazing pasture (RMSEsim1 = 0.0485 vs. RMSEsim2 = 0.0602 cm3 cm-3), while for the rainfed maize plots SIM1 shows lower RMSE (average for all plots RMSE = 0.0542 cm3 cm-3) compared to the site-specific calibration model (SIM2 – average for all plots RMSE = 0.0645 cm3 cm-3). Finally, OPTRAM estimations are close to in situ measurement values while Surface Soil Moisture at 1 km (SSM1 km) tends to underestimate the measurements during maize crop growing season. Soil moisture retrieval from high-resolution Sentinel-2 optical images allows water stress conditions to be effectively mapped, supporting decision making in irrigation scheduling and other crop management

Impact of Biochar Formulation on the Release of Particulate Matter and on Short-Term Agronomic Performance

When applied in agriculture, the solid carbonaceous residue of anoxic thermochemical conversion of biomass (biochar) has variable effects on soil, crop yields, and climate mitigation. Biochar can be added to soil as powder or as pellets. While powdered forms have demonstrated effects on crop yields, they may release coarse and fine particulate that can be transported into the atmosphere during production, packaging, storage, transport, and distribution. Biochar weathering and wind erosion may also cause the release of particles. Particulate matter (PM) released from biochar may have negative effects on human health and increase the atmospheric burden of shortwave absorbing black carbon aerosols with non-negligible effects on atmospheric radiative forcing. Pelletizing feedstock before the thermochemical conversion and moistening of biochar are expected to reduce the emission of PM in the processing and post-processing phases while also increasing the mean residence time of Carbon in soils. The impact of biochar formulation (pellet and non-pellet) on the release of coarse and fine particulate in wet and dry conditions was assessed in a laboratory experiment. In parallel, the effects of pellet and non-pellet formulations on growth and yield of processing tomato plants were tested in a pot experiment. Results show that pelletization and moistening substantially reduce the amount of fine particles released and are therefore practices that should be adopted to maximize the mitigation potential of biochar. A reduction of tomato yield was observed in pellet treatment, suggesting that the higher interface area of powdered biochar may boost productivity in the short term. This work points to the existence of a tradeoff between the short-term maximization of agronomic benefits and the minimization of harmful effects due to particulate release

Studio del ciclo del carbonio in relazione con la sostenibilità della fertilizzazione organica in arboricoltura da legno in ambiente mediterraneo

Short Rotation Woody Crops (SRWC) is a method of cultivation of selected material of fast growing species (poplar, willow, eucalyptus, black locust) to produce in short time large quantity of biomass for energy purposes (calorific or/and electric energy). In a SRWC very high plant density per hectare is used (from 5-10,000 to 15,000 plants per hectare), the rotation age is 2-3 years. It is estimated that a SRWC Eucalyptus requires an average of at least 100 kg of N year, thus the use of irrigation and fertilization to meet the demand of this type of crop is not feasible because is a very uneconomic crop. Irrigation can be used as a rescue intervention and inorganic fertilizer at planting and after the cuts. For this reason, the fertilization with manure, where available, may be an attractive option because allows to properly dispose of the sewage and to give to the plant nutrients necessary for growth. The European Union Directive 91/676/EEC, known as Nitrates Directive, has dictated basic agronomic principles regarding the use of animal manure source, zoo-technical and waste waters from small food companies. The use of nitrification inhibitors together with animal effluents may be beneficial for nutrient recycling, soil quality, plant productivity and greenhouse gas emission, and offers economic advantages to make it an alternative to conventional fertilizers. The aim of this research was to investigate the sustainability of organic fertilization combined with a nitrification inhibitor in relations to carbon dynamics. Were compared the effectiveness of the nitrification inhibitor 3,4 dimethyl pyrazole phosphate (DMPP), together with the addition of fresh organic matter (bovine effluent, BE) to the soil of a short rotation forestry. The results of microcosm experiments suggested that the combined use of DMPP and BE could be a good solution to limit the drastic effect of BE application on soil biological properties and microbial dynamics. The preliminary study of field application of DMPP and BE evidenced that this strategy of fertilization could be also a good solution to reduce the ammonia and carbon dioxide emissions and to improve the productivity in SRWC agro-ecosystems of Mediterranean environment and preserve the soil functions.Le culture da legno a ciclo breve (SRWC) sono un metodo di coltivazione di materiale selezionato a rapida crescita di specie (pioppo, salice, eucalipto, robinia) per produrre in breve tempo grande quantità di biomassa a fini energetici (calorifico e / o elettrici energia). Una densità di piantw molto alta per ettaro viene utilizzata (da 5-10.000 a 15.000 piante per ettaro) e l'età di rotazione è di 2-3 anni. È stimato che un Eucalyptus SRWC richiede un media di almeno 100 kg di N anni, quindi l'uso di irrigazione e fertilizzazione per soddisfare la domanda di questo tipo di coltura non è possibile perché è una coltura non redditizia. Per questo motivo, la concimazione con liquami zootecnici, può essere un'opzione interessante in quanto permette di smaltire correttamente i liquami e di dare alla pianta le sostanze nutritive necessarie per la crescita. La Direttiva europea 91/676/CEE, nota come Direttiva sui nitrati, ha dettato le basi agronomiche per quanto riguarda l'uso di concime animale fonte, zoo-tecniche e le acque reflue provenienti da piccole le aziende alimentari. L'uso di inibitori della nitrificazione insieme ad effluenti animali può essere utile per il riciclaggio dei nutrienti, la qualità del suolo, la produttività e le emissioni di gas serra, e offre vantaggi economici tali da renderli un'alternativa ai fertilizzanti convenzionali. Lo scopo di questa ricerca è stato quello di indagare la sostenibilità della concimazione organica combinata con un inibitore della nitrificazione in relazioni con le dinamiche di carbonio nel suolo. E’ stata confrontata l'efficacia dell’ inibitore della nitrificazione 3,4 dimetil pirazolofosfato (DMPP), insieme con l'aggiunta di un effluente bovino,( BE) al terreno di una SRWC. I risultati di esperimenti in microcosmi suggeriscono che l'uso combinato di DMPP e BE potrebbe essere un buon soluzione per limitare l'effetto drastico dell’applicazione di BE sulle proprietà biologiche del suolo. Lo studio preliminare del campo applicazione di DMPP e BE ha evidenziato che questo strategia di fertilizzazione potrebbe essere anche un buon soluzione per ridurre le emissioni di ammoniaca e anidride carbonica e per migliorare la produttività economica in agro-ecosistemi di ambiente mediterraneo e preservare le funzioni del suolo.Dottorato di ricerca in Ecologia forestal

Temperature Effects on Recovery Time of Bacterial Growth After Rewetting Dry Soil.

The effect of temperature on the recovery of bacterial growth after rewetting dry soil was measured in a soil that responded with bacterial growth increasing immediately upon rewetting in a linear fashion (type (i) response sensu Meisner et al. (Soil Biol Biochem 66: 188-192, 2013)). The soil was air-dried for 4 days and then rewetted at different temperatures. Bacterial growth over time was then estimated using the leucine incorporation method. At 25 °C, the recovery of bacterial growth to levels of a wet control soil was rapid, within 6 h, while at 15 °C, recovery time increased to around 60 h, becoming more than a week at 5 °C. The temperature dependency of the recovery time was well modeled by a square root function. Thus, temperature will not only directly affect growth rates but also affect length of transition periods, like resuscitation after a drying event. The temperature during the rewetting event thus has to be taken into consideration when analyzing the microbial response dynamics

Assessing the Influence of Summer Organic Fertilization Combined with Nitrogen Inhibitor on a Short Rotation Woody Crop in Mediterranean Environment

The European Union Directive 91/676/EEC, known as Nitrates Directive, has dictated basic agronomic principles regarding the use of animal manure source as well as livestock and waste waters from small food companies. The use of nitrification inhibitors together with animal effluents as organic fertilizers could be beneficial for nutrient recycling, plant productivity, and greenhouse gas emission and could offer economic advantages as alternative to conventional fertilizers especially in the Mediterranean region. The aim of the present study was to investigate differences in plant productivity between bovine effluent treatments with (or without) addition of a nitrification inhibitor (3,4 DMPP) in a short rotation woody crop system. Results of the field experiment carried out in a Mediterranean dry environment indicated that the proposed strategy could improve tree growth with indirect, beneficial effects for agroforestry systems