UN sustainable development goals include “to raise awareness of soil organic matter as a key attribute of soils to illustrate its importance for soil functions and ecosystem services, noting that soils contribute to basic human needs like food, clean water, and clean air, and are a major carrier for biodiversity. Extensive land and soil degradation still occurs all over the world and fertile soil resources are still rapidly depleted.”
Soil is a biological construct, powdered rock inhabited by thousands of species of viruses, bacteria, fungi, protozoa, nematodes, enchytraeids, collembolas, mites, earthworms, insects and some vertebrates. Soil formation is an ongoing process and its interface with agriculture may be degradative, not necessarily progressive. It has a major role in above-ground biodiversity, control of plant, animal and human pests and diseases, and climate regulation.
At Maori Point, we seriously endeavour to promote soil formation and soil health. We recognize that soil is more than the substrate for growing our vines. It has a vital role in preventing climate change: there is more organic matter in soils than in all tropical forests combined; and the top one metre of soils globally contains 3 times as much carbon as the atmosphere. Generating new healthy soil helps combat global warming, perhaps as much or more than planting trees.
We are in the slightly unusual situation of orchestrating the development of new soil from powdered glacial rocks. At present, our soil is based on recent glacial outwash: sands, pebbles, rocks and boulders with surface layers of finely powdered glacial rock (wind-blown loess); with very low organic content. Natural soils develop slowly over geological time, and by understanding this natural process we can intervene and accelerate their formation. Soil organic matter comes mainly from biological fixation of carbon and nitrogen from the air. To do this, soil micro-organisms require phosphate, calcium, magnesium, a range of trace elements, and, of course, water and oxygen. After planting our vines in what looked like fine pale sand, it took only a few years for surface soil to become rich and black.
How was this transformation achieved? Our organic matter is the product both of soil microorganisms and of plants growing in the inter-rows, mulched and thrown back under the vines. Products of the vines are recycled back to the land. Wine is bottled and sold, but grape pressings and prunings are composted and replaced back in the vineyard. Geological formation of soil occurs with the slow generation of phosphate and minerals by microbiological digestion of powdered rock. We short-circuit this process by importing powdered phosphate rock and crushed dolomite, spreading these on the soil each winter. They are slowly incorporated into our soil, and our busy soil fungi and bacteria grow on each particle and progressively release phosphate, magnesium and calcium, making these available to the vines and inter-row plants. Industrial agriculture would employ purified chemicals, giving transient encouragement of plant growth and then being washed into the subsoil and polluting sub-surface water. Mycorrhyzal fungi bridge solid particles of phosphate and dolomitic rock with vine roots, transferring nutrients with minimal loss. We consider that our system is both economically and ecologically more efficient than an industrial chemical approach.