Biochars in soils : towards the required level of scientific understanding

Key priorities in biochar research for future guidance of sustainable policy development have been identified by expert assessment within the COST Action TD1107. The current level of scientific understanding (LOSU) regarding the consequences of biochar application to soil were explored. Five broad thematic areas of biochar research were addressed: soil biodiversity and ecotoxicology, soil organic matter and greenhouse gas (GHG) emissions, soil physical properties, nutrient cycles and crop production, and soil remediation. The highest future research priorities regarding biochar's effects in soils were: functional redundancy within soil microbial communities, bioavailability of biochar's contaminants to soil biota, soil organic matter stability, GHG emissions, soil formation, soil hydrology, nutrient cycling due to microbial priming as well as altered rhizosphere ecology, and soil pH buffering capacity. Methodological and other constraints to achieve the required LOSU are discussed and options for efficient progress of biochar research and sustainable application to soil are presented.Peer reviewe

THE ROLE OF MINERAL NUTRITION ON YIELDS AND FRUIT QUALITY IN GRAPEVINE, PEAR AND APPLE

ABSTRACT Fertilization of temperate fruit trees, such as grapevine ( Vitis spp.), apple ( Malus domestica), and pear ( Pyrus communis) is an important tool to achive maximum yield and fruit quality. Fertilizers are provided when soil fertility does not allow trees to express their genetic potential, and time and rate of application should be scheduled to promote fruit quality. Grapevine berries, must and wine quality are affected principally by N, that regulate the synthesis of some important compounds, such as anthocyanins, which are responsible for coloring of the must and the wine. Fermenation of the must may stop in grapes with low concentration of N because N is requested in high amount by yeasts. An N excess may increase the pulp to peel ratio, diluting the concentration of anthocyanins and promoting the migration of anthocyanins from berries to the growing plant organs; a decrease of grape juice soluble solid concentration is also expected because of an increase in vegetative growth. Potassium is also important for wine quality contributing to adequate berry maturation, concentration of sugars, synthesis of phenols and the regulation of pH and acidity. In apple and pear, Ca and K are important for fruit quality and storage. Potassium is the most important component of fruit, however, any excess should be avoided and an adequate K:Ca balance should be achieved. Adequate concentration of Ca in the fruit prevents pre- and post-harvest fruit disorders and, at the same time, increases tolerance to pathogens. Although N promotes adequate growth soil N availability should be monitored to avoid excessive N uptake that may decrease fruit skin color and storability

Effect of soil management and Biochar addition on productivity and vegetable quality on a tomato-lettuce rotation

Conventional management practices in horticulture allow obtaining high standard of productivity in terms of quantity and quality although their long-term impacts on the agricultural soils are often negative and responsible for the loss of substantial amounts of soil organic matter. On the other hand sustainable agricultural practices such as minimum tillage promote the conservation of the native soil organic matter improving progressively the soil fertility. The objective of this study was to compare in a tomato-lettuce rotation the effect of 1) management practices (conventional or sustainable) and 2) biochar additions (with or without biochar) on total productivity and quality of tomato and lettuce. The two-year-experiment was conducted in a tunnel on 24 lysimeters (1.44 m2 each), 12 cultivated with lettuce (Lactuca sativa L.) and the other 12 with tomato (Solanum lycopersicum). The lysimeters that during the first year were used for tomato in the second year were cultivated with lettuce. Biochar was obtained from pirolysis at 500\ub0C of fruit trees pruning residues and added at a dose of 30 ton ha-1. Total commercial productivity was higher in tomato only in the second year grown with sustainable practices compared to traditional ones. This was mainly due to the less incidence of brown rot on the fruit, probably for the better management of water availability with sustainable practices. Although biochar did not influenced total commercial productivity its addition significantly reduced the amount of brown rot. Differently, lettuce productivity was not influenced by the management practices in the two year. Addition of biochar improved the productivity in the sustainable management practice of 14% and 36% in 2010 and 2011, respectively. Also the amount of nitrate in lettuce leaves was significantly reduced in presence of biochar (14% and 10% less in the sustainable and traditional treatment, respectively). The use of biochar in combination with sustainable practices seems to be a promising alternative to improve quality of the commercial product especially in case of leaf vegetable crops like lettuce, spinach and rocket

Nitrogen partitioning in apple trees as affected by application time

15Nitrogen-ammonium nitrate was applied to four 'Mutsu' apple (Malus x domestica Borkh.) trees 40 days before harvest of 1996 (summer supplied nitrogen, SUN) and four others at full bloom in 1997 (spring supplied nitrogen, SPN) to evaluate the effect of application timing on N partitioning in mature trees. At leaf fall the largest amount of SUN was partitioned to roots and 2- to 4-year-old wood; the largest amount of SPN was partitioned to fruit and leaves and only a small amount detected in the roots. SUN did not increase N concentration in fruit or modify fruit firmness and soluble solids concentration, although it contributed to building up N reserves in the perennial woody organs. In 1997, as a result of the different timings of N supply, two sources of labeled N were distinguished and monitored in the vegetative organs: 1) the remobilized N, taken up in summer of 1996, stored in winter and then translocated to the growing tissues; 2) the newly absorbed N, taken up and moved to the canopy after the 1997 spring supply. Both fractions of remobilized and newly uptaken labeled N contributed to leaf and fruit N. Remobilized 15N was provided principally by roots which, from August to leaf fall, decreased their percentage of 15N by ≃18%, replacing the labeled with unlabeled N to maintain a constant concentration of total N

The effects of irradiation and artificial aging on the wear behaviour of UHMWPE.

Ultra-high-molecular-weight-polyethylene (UHMWPE) for hip implants can present serious clinical problems: the cyclic nature of the contact stresses at the articular surface can lead to pitting, delamination and crystallinity changes of the polymer with formation of PE debris, which may lead to extensive bone loss around the implant and consequently osteolysis and implant loosening. The effects of different sterilization methods have been studied by various authors, but no one produced a full conclusive verdict (1,2). To assess long term stability of polymers, various accelerated aging methods have been developed. In this study, an internal protocol was developed to evaluate the effects of the accelerated aging on wear. Three EtO-sterilised and six gamma-irradiated (standard 3 Mrads dose in air) UHMWPE acetabular cups (Chirulen GUR 1050, POLY HI SOLIDUR, France) were aged in air at 80\ub0C for 4 weeks and thereafter tested in conjunction with twelve 28-mm CoCrMo femoral heads. Wear tests were carried out using a 12-station hip joint simulator (Shore Western, USA) run for 3 million cycles, with bovine calf serum as lubricant. A frequency of 1 Hz, according to the rotation test frequency, was applied with a sinusoidal load having a peak magnitude of about 2 kN. Wear behaviour was evaluated by gravimetric measurements and Raman analysis. Since Raman spectra reflect PE morphology, Raman spectroscopy was used to investigate the crystallinity changes induced by aging and wear testing. Micro-Raman spectra were obtained in a non-destructive way using a Jasco NRS-2000C instrument (exc=488 nm, 20 7 magnification). For each cup, 12 spectra were recorded in the inner surface within 1.5 mm from the centre, the most worn area. Crystallinity (C%) was determined from Raman spectra using the partial least-squares (PLS) regression. Significant differences were observed between the wear behaviours of the two sets of acetabular cups after 3 million cycles ( = 0.0001). The mean C% values obtained for untreated gamma and EtO-sterilised UHMWPE unworn cups were significantly different (62 and 60%, respectively). Upon ageing significant changes in C% were observed for all the cups and were more pronounced for gamma-sterilised cups (meanly from about 62% to 65%) than for EtO-sterilised cups (meanly from 60% to 61%). Upon wear testing of the gamma-sterilised cups, only three samples showed significant increases in C%. Conversely, all the EtO-sterilized cups showed significant C% changes: one cup showed a C% increase (from (60.9\ub10.2)% to (61.9\ub10.4)%), while the other two underwent a C% decrease (from (60.3\ub10.3)% to (56.4\ub10.7)% and from (60.9\ub10.3)% to (59.4\ub10.4)%). The higher crystallinity found for the gamma-sterilised cups can be explained by considering that the energy of the gamma rays is sufficiently high to break the UHMWPE polymeric chains, resulting in a reduction of molecular weight and in a corresponding increase in crystallinity. Raman spectroscopy proved a valid tool to non-destructively monitor the C% changes the samples underwent upon aging and wear tests. By Raman-PLS analysis it was confirmed that aging affected more significantly the morphology and wear behaviour of the gamma-sterilised cups; also the EtO-sterilised cups underwent detectable C% changes, which, however, did not affect so dramatically wear behaviour

Modelling transformational adaptation to climate change among crop farming systems in Romagna, Italy

As the impact of climate change on the agricultural sector has begun to manifest itself in its severity, adaptation planning has come under scrutiny for favoring the preservation of status-quo conditions over more substantial changes. The uptake of transformational adaptations, involving a significant re-structuring of the agricultural system, is however hindered by a lack of assessment tools capable of quantifying the effects of these often more complex, far-reaching, and unprecedented changes. Agent-based models can simulate decision processes and multi-level feedbacks between system components and may therefore illustrate how transformational adaptations emerge and help identify cases where their implementation is necessary and desirable. We explore this modelling potential and aim to quantify (1) how climate change, farmer behavior and water policies may influence strategic adaptation decision-making at the farm-level, (2) the extent to which implemented adaptations represent transformations, and (3) their impact on farm structure and wider socio-ecological change. We investigate these aims through a case study of crop farming systems in the drought-prone historical region of Romagna (NE Italy), integrating insight from stakeholder interviews, local reports, spatially-explicit biophysical data and behavioral theory in the construction of an agent-based model. Results show that, on average, more than half of all implemented adaptations are transformations, thereby requiring important social and financial investments from farmers. The number of implemented transformations is highest in scenarios where drought risk perception among farmers is more widespread, notably in scenarios simulating drier climates, more adaptive behaviors and policies promoting greater water use efficiency. Under higher drought risk perception, farmers are motivated to explore a broader set of adaptations, including those outside of the trajectory determined by their farming strategy. This process particularly favors the implementation of transformational increases in farm size and irrigated area, eventually stimulating farmers to adopt an expansionist strategy. Regionally, these adaptations lead to the smallest decline in agricultural extent with fewest, yet highest profit-earning farmers, largely exacerbating presently occurring trends. Under policy scenarios simulating increased irrigation availability, fewer farmers initially experience drought and therefore perceive a drought risk. Consequently, fewer farmers undertake transformational adaptations and switch from a contractive to an expansive strategy, culminating in a relatively smaller and less profitable agricultural extent despite a larger farmer population. As transformative changes to farming strategy trigger farmers to engage in new path-dependencies, aims of water policies may therefore rebound into unintended effects, emphasizing the importance of accounting for transformational perspectives

Nitrogen accumulation and leaf gas exchange in apple trees grafted on M.26 EMLA, M.9 EMLA and mark rootstocks under low soil temperature and drought stress

Two-year-old apple trees of cv Jonee grafted on Mark, M.9 EMLA and M.26 EMLA rootstocks were exposed for 10 days to low root temperature (8± 1°C) and drought stress to evaluate, over a 3-day period, the accumulation of labeled nitrogen (N) in root and scion and leaf gas exchange rate under adverse soil environment. M.9 EMLA showed a similar and a higher percentage of N derived from fertilizer (NDFF) in the xylem sap than M.26 EMLA and Mark, respectively. Unlike drought stress, low root temperature was effective in reducing NDFF in the xylem sap, compared to control trees. While not affected by rootstock, the labeled N removed by trees in control soil was similar and higher (P=0.09) than in dry and low temperature ones, respectively. Labeled N increased from Day 1 to Day 3 in the xylem sap as well as in the whole tree. Three days after N supply, most of the labeled N was accumulated in the root and less than 16% was detected in the shoot. A linear correlation was observed between the percentage of NDFF in the xylem sap and the amount of labeled N detected in shoot both one and three days after fertilization. Carbon assimilation (A) and transpiration (E) rates were higher in control, intermediate in low temperature and were lowest in drought-stressed trees. M.9 EMLA showed the highest A under optimal soil conditions but the lowest under drought stress. Low root temperature was more effective than drought stress in depressing N absorption while drought stress was more effective than low root temperature in decreasing leaf gas exchange