Exhausted Grape Marc Derived Biochars: Effect of Pyrolysis Temperature on the Yield and Quality of Biochar for Soil Amendment

The present study focuses on the valorisation of winery industry wastes through slow pyrolysis of exhausted grape marc (EGM). The optimal pyrolysis parameters were firstly identified by small scale experiments carried out using thermogravimetric analysis. Nine pyrolysis temperatures were tested and their influence on the decomposition of the EGM residue and biochar yield was evaluated. Then, biochar production was conducted in a pilot plant at three chosen temperatures (450, 500 and 550 °C) at which the biochar was shown to be stable. The effects of biochar application to soil with respect to plant (ryegrass) growth was also evaluated. Pyrolysis of EGM at the 450–550 °C temperature range has been shown to generate thermally stable and nutrient-rich biochars, but only the biochar produced at 450 °C showed a marked benefit effect of ryegrass growth.

Working with dairy farmers to improve their pasture management skills through better understanding the principles of ryegrass growth

The relationships between leaf regrowth stage, pre- and post-grazing pasture covers, and grazing rotation length are complex. Despite the existence of well-documented grazing guidelines for managing these relationships, implementation on-farm is highly variable indicating that skill levels are often inadequate and/or farmers are not convinced of the benefits. Twenty dairy farm managers and assistant managers from the Hopkins Farming Group in the lower North Island engaged in structured observation and discussion with experts to test the potential of the 3-leaf grazing technique for increasing pasture production and reducing imported supplement use from mid-spring to mid-autumn. The farmer members of the study group initially had little knowledge of the principles of ryegrass growth at the plant level, and how their management influences pasture production and persistence. Grazing management skills developed by group members during the process included: identification of pasture species within the sward, including perennial ryegrass; identification of leaf morphology, tillers, tiller buds and daughter tillers; pasture health checks to understand when new tillers appeared and their grazing and nutrient needs; and the importance of grazing residuals for future pasture quality. Pasture productivity, as measured by the amount of silage conserved, increased by approximately 0.45 t DM/ha during the 6 months of study through the application of this grazing management technique. Managing grazing using the 3-leaf technique requires a greater depth of knowledge than previous, simple, rotation length-based systems. Many farmers are concerned about the lack of persistence of new ryegrass cultivars, whereas it may be their management practices that have a greater influence.

Phytoextraction, Accumulation and Toxicological Effects of 1-Tetradecyl-3-Methylimidazolium Ionic Liquid in Ryegrass

Ionic liquids are widely used in many fields due to their extremely tunable nature and exceptional properties. The extensive application of ionic liquids raises great concerns regarding their bioaccumulation potential and adverse effects on organisms.Green plants have a great potential for uptake of persistent xenobiotics from aquatic and terrestrial environment. However, the assimilation and bioaccumulation of 1-tetradecyl-3-methylimidazolium bromide ([C14mim]Br) has not been studied in plantsyet. In order to explore the phytoaccumulationof [C14mim]+, ryegrass were exposed to [C14mim]Br with hydroponic experiment.The effects of [C14mim]Brdosages on growth index, chlorophyll content, malondialdehyde (MAD) content and antioxidant enzyme activity of ryegrass were investigated. The toxic effects of[C14mim]Bron ryegrass growth increased with increasing initial concentration. The high initial concentration treatment resulted in rapid changes in physiological characteristics in ryegrass tissue. [C14mim]+ions were mainly accumulated in root tissue and partly translocated to the above ground part of ryegrass.[C14mim]+was observed in the highest concentration (314.35 µg/gin root and 101.42 µg/gin aboveground partsof ryegrass) with 10 mg/L of [C14mim]Br.Our results demonstrated that ryegrass can uptake and accumulate [C14mim]+ and is therefore a suitable species for phytroremediationof trace amount of [C14mim]+ and possibly other ionic liquids.

Biochar-Compost Interactions as Affected by Weathering: Effects on Biological Stability and Plant Growth

Biochar addition to compost is of growing interest as soil amendment. However, little is known about the evolution of material properties of biochar-compost mixtures and their effect on plants after exposure to physical weathering. This study aimed to investigate the physico-chemical characteristics of fresh and weathered biochar-compost mixtures, their biological stability and their effect on ryegrass growth. To this end, we used the contrasting stable isotope signatures of biochar and compost to follow their behavior in biochar-compost mixtures subjected to artificial weathering during 1-year of incubation. We assessed their impact on ryegrass growth during a 4-week greenhouse pot experiment. Weathering treatment resulted in strong leaching of labile compounds. However, biochar-compost interactions led to reduced mass loss and fixed carbon retention during weathering of mixtures. Moreover, weathering increased carbon mineralization of biochar-compost mixtures, probably due to the protection of labile compounds from compost within biochar structure, as well as leaching of labile biochar compounds inhibiting microbial activity. After soil application, weathered mixtures could have positive effects on biomass production. We conclude that biochar-compost interactions on soil microbial activity and plant growth are evolving after physical weathering depending on biochar production conditions.