Using alder, biochar and seaweed as an agro-ecological improver for nutrient and water retention in semi-arid viticulture

We propose to conduct field soil experiments in the Arrighi Winery on Elba Island to determine the impact they have on vine growth and yield. This experiment will involve amending the soil with two different natural additives – biochar and/or dried seaweed. Small experimental plots will be loading with different concentrations of each (biochar or seaweed) or a combination of both. These field experiments will be monitored throughout the experimental period to investigate water holding capacity, nutrient storage, carbon sequestration and nutrient/micro-nutrient uptake in the vine/grape. Each plot will be evaluated in terms of yield and grape quality to determine which soil amendment strategy is best for the Arrighi Winery. In addition, alder trees will be planted to help with nitrogen capture and fixation in the soil, since it is a nitrogen fixing tree. It is predicted that all three amendment strategies will benefit the vine/grape production for the Arrighi Winery, as well as improving soil health, sustainable farming and regional biodiversity.

Previous experimental research undertaken by SIBL, Durham University has shown that biochar and seaweed can improve the growth of trees and arable crops, increases water retention, nutrients and micronutrients in the soil, and carbon capture. Climate change predictions estimate less rainfall in the Elba region and thus water scarcity will become a real issue – enabling water retention in the soil through biochar and seaweed is one natural solution that can be used. In addition, the alder tree is a “nitrogen-fixing” tree and thus will draw down nitrogen from the atmosphere into the soil – which can then be used by neighbouring plants. All of these amendments will improve the soil health and thus, benefitting the plants living on top of it. The predicted outcome of this study is that it will yield greater vine growth and grape yield. As yet unknown, the different soil amendment (e.g., using seaweed and/or biochar) may even result in different textural flavours in the grape!

Prof Darren Gröcke is the Director of the Stable Isotope Biogeochemistry Laboratory (SIBL) at Durham University, UK. Over the past decade Darren and his group have worked on many aspects of seaweed, such as using them to monitor nitrogen pollution in estuaries and coastlines, their ability to absorb trace metals, as an estuarine bioremediation tool and as a biofertiliser in agriculture. This has also included the use of biochar in agricultural soils (in collaboration with Prof Mike Church – environmental archaeologist specialising in charcoal) as a method of carbon capture, soil health and growth responses in trees in arable crops. Currently, SIBL is working with a group of 50 farmers in Cumbria, England, researching sustainable and environmental methods in arable crops to improve soil health and food security in the region; it also involves designing biodiverse forests in unfarmable areas (e.g., corners of fields). Since much of this research takes multiple years to perform the experiments, publications are in progress, but here are a few related to seaweed and investigating modern and past agricultural amendment strategies:

Alldred, F.C., Gröcke, D.R., Jackson, S.E. (2024). Nitrogen isotope variability of macroalgae from a small fishing village, Staithes Harbour, Yorkshire, UK. Marine Pollution Bulletin 207:116828. https://doi.org/10.1016/j.marpolbul.2024.116828

Blanz, M., Gröcke, D.R., Martin, P., Church, M.J. (2024). The effect of seaweed fertilisation on sulfur isotope ratios (δ³⁴S) and grain size in barley: Implications for agronomy and archaeological research. Frontiers in Environmental Archaeology 3:1465082. https://doi.org/10.3389/fearc.2024.1465082

Styring, A.K., Vaiglova, P., Bogaard, A., Church, M.J., Gröcke, D.R., Larsson, M., Liu, X., Stroud, E., Szpak, P., Wallace, M.P. (2024). Recommendations for stable isotope analysis of charred archaeological crop remains. Frontiers in Environmental Archaeology 3:1470375. https://doi.org/10.3389/fearc.2024.1470375

Treasure, E.R., Gröcke, D.R., Lester, J.J., Bishop, R.R., Church, M.J. (2024). Further investigation into the impact of manuring on stable carbon (δ13C) and nitrogen isotope (δ15N) values in pulses: a four-year experiment examining Celtic bean (Vicia faba). Archaeological and Anthropological Sciences 16:130. https://doi.org/10.1007/s12520-024-02045-x

Alldred, F.C., Gröcke, D.R., Leung, C.Y., Wright, L.P., Banfield, N. (2023). Diffuse and concentrated nitrogen sewage pollution in island environments with differing treatment systems. Scientific Reports 13:4838. https://doi.org/10.1038/s41598-023-32105-6

Gröcke, D.R., Treasure, E.R., Lester, J.J., Gron, K.J., & Church, M.J. (2021). Effects of marine biofertilisation on Celtic bean carbon, nitrogen and sulphur isotopes: implications for reconstructing past diet and farming practices. Rapid Communications in Mass Spectrometry 35:e8985. https://doi.org/10.1002/rcm.8985

Treasure, E.R., Gröcke, D.R., Caseldine, A.S. & Church, M.J. (2019). Neolithic farming and wild plant exploitation in western Britain: archaeobotanical and crop stable isotope evidence from Wales (c. 4000–2200 cal BC). Proceedings of the Prehistoric Society 85:193–222. https://doi.org/10.1017/ppr.2019.12

This proposal can be subdivided into three main budget streams:

(1) Experimental: this would involve the purchase and installation of environmental monitoring equipment, delivery and introduction of biochar and seaweed into the soils. This would involve fieldtrips by the group to install the instruments and amend the soils. During this phase we will incorporate a citizen science aspect to the project where we will train local volunteers and/or employees of the Arrighi Winery to regularly monitor, use and extract environmental data from the instruments installed – some will be automatic but other instruments will have to be manually used to obtain environmental data (e.g., carbon dioxide gas monitoring). Indicative costs for this aspect of the project are €95,000 which includes all costs related to fieldwork such as air-travel, accommodation and subsidence.

(2) Analytical: during the experimental period, many samples will be collected for elemental and isotopic analysis (e.g., soil, water, plants) and microbiology. This will be regularly done during the growing season and once again, in order to reduce travel costs and limit our own carbon budget we would train local volunteers and/or employees of the Arrighi Winery to collect these samples and post them to SIBL. Indicative costs for this aspect of the project are €40,000, including research assistant time to prepare all the samples in SIBL.

(3) Reporting: this study will benefit two undergraduate students in SIBL who will undertake dissertations on this project. Each will produce a report at the end of growing season 1 and 2, that will culminate into a single report that will be generate by Prof Darren Gröcke for the Arrighi Winery. The outcome of this study will also be presented to the Arrighi Winery and local stakeholders on Elba Island to develop an-island wide model for Elba’s agricultural community that will enhance and sustain the natural biodiversity on the island in a changing climate. Indicative costs for this aspect of the project are €15,000.

A total indicative budget of €150,000 will enable this 2+-year experimental project on Arrighi Winery to meet the primary objective of the challenge, “importance of harmonizing viticulture with natural ecosystems, fostering a sustainable and resilient agricultural model that strengthens both vineyard productivity and environmental balance.” SIBL looks forward to working with Arrighi Winery on this exciting, sustainable and innovative project.