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Biochar increases soil enzyme activities in two contrasting pastoral soils under different grazing management
(CSIRO Publishing, 2022-12) Garbuz S; Mackay A; Camps-Arbestain M; Devantier B; Minor M; Solaiman Z
Context: Soil enzyme activities are key regulators of carbon and nutrient cycling in grazed pastures. Aims: We investigated the effect of biochar addition on the activity of seven enzymes involved in the carbon, nitrogen and phosphorus cycles in a Sil-Andic Andosol and a Dystric Cambisol under permanent pastures. Methods: The study consisted of a one-year field-based mesocosm experiment involving four pastures under different nutrient and livestock practices: with and without effluent under dairy cow grazing on the Andosol, and with either nil or high phosphorus fertiliser input under sheep grazing on the Cambisol. Soil treatments were: (1) willow biochar added at 1% w/w; (2) lime added at the liming equivalence of biochar (positive control); (3) no amendments (negative control). Key results: Compared with the Cambisol, the Andosol had higher dehydrogenase, urease, alkaline and acid phosphatase and, especially, nitrate-reductase activities, aligning with its higher pH and fertility. In both soils, biochar addition increased the activity of all enzymes, except for acid phosphatase and peroxidase; lime addition increased peroxidase and nitrate-reductase activity. Conclusions: The increased enzyme activity was strongly positively correlated with soil biological activity following biochar addition. Biochar caused a 40-45% increase in cellulase activity, attributed to increased root biomass following biochar addition. The response in acid and alkaline phosphatase activity can be attributed to the impact of biochar and lime addition on soil pH. Implications: The results provide more insights in realising the potential benefits of biochar to the provision of ecosystem services for grazed pastures.
Repurposing Grape Marc in marlborough: The Way Forward - from Assessment of Options to Next Steps
(Marlborough District Council, 2020-06-03) Jones J; McLaren S; Chen Q
Five options for repurposing grape marc in Marlborough have been investigated in the techno-enviro-economic analyses presented in two reports and at two fora . The two fora were attended by wine industry representatives. A number of the participants attending the second forum have agreed to establish a Working Group. A first meeting is planned, to which representatives of the major peak bodies and wine industry groups will be invited. The Working Group will determine the option or options to take to Stage II development. This study was initiated by the Marlborough District Council and is funded in part by them and by the Waste Minimisation Fund. The motivation to consider alternatives for repurposing grape marc has a number of contributing factors; (i), the quantity of grape marc is large, estimated in 2019 at 46,000 tonnes from 305,467 tonnes of pressed grapes, which produce an estimated 218 million litres of wine; (ii), the vineyard area is expanding rapidly, from 25,135 ha (2017) to 27,808 ha (2020). (iii), earlier attempts to compost grape marc led to prosecution of some operators for poor environmental outcomes; (iv), direct land-spreading of raw grape marc has arisen as the preferred activity but is not without environmental risk; (v), both direct land-spreading and composting require land and necessitate take-back arrangements with winegrowers; and (vi), neither composting nor direct land-spreading offer the opportunity to value add. All five options investigated here avoid that risk. They are: • best-practice composting; • drying to make dried grape marc for sale; • combustion to generate steam to make electricity; • gasification to produce electricity in gas engines and excess heat; and, • pyrolysis to produce biochar/charcoal and excess heat. Some calculations are also included for comparison with direct land-spreading of raw grape marc. A number of these options have viable commercialisation pathways that balance positive environmental outcomes with volume reduction of grape marc and profitability. They all require capital investment. This report summarises the options and presents the next steps towards commercialisation. The Working Group will further assess and refine these options.
Research Report - Repurposing Grape Marc
(Marlborough District Council, 2020-03-06) Jones JR; McLaren S; Chen Q; Seraj M
Section 1. Executive Report (page 2) Section 2. Background to the Project (page 25) Section 3. Detail Report - Thermal Processes: Technical and Economic Analysis (page 35) Section 4. Detail Report - Environmental Analysis by Carbon Footprint (page 69)

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