Now, this International Year of Soils 2015 merits our Fellowship’s recognition, reflection and response:
An annual World Soil Day was initiated by the UN on December 5th 2014 but 2015 has all year to hail soils! Since soils yield 95% of our global diet, plus many other ecosystem services (carbon capture, water filtration and storage, ‘culture’..) it is self-evident that they’re the basis of all farming systems and ‘where the answers lie’ gifting true sustainability. Long ago the Psalmist (65:9) wrote, ‘You care for the land and water it; You enrich it abundantly’. As with a farming business, it is not the exact amount of organic matter that soils contain so much as its turnover rate that indicates dynamic fertility and soil health. Threats to soil health include erosion, exhaustion, pH imbalance, wetness, drought and infestation with weeds, pests and diseases. Solutions offered by good soil management – proper land husbandry – to these respective issues include:- soil conservation, soil nutrient management, pH adjustment (usually to 6.5), drainage, moisture conservation and/or irrigation and positive soil health through proper weed, pest and disease prevention and control.
Worldwide, around one-third of all farmed soils are reckoned by the FAO to be degraded to varying degrees, and this proportion is increasing. Soil degradation may be due to erosion, compaction, soil sealing, salinisation, depletion of soil organic matter and nutrients, acidification, pollution and other processes caused by unsustainable land management practices. Furthermore, while world population grew by some 30% between 1990 and 2010, soil losses are estimated at some 24 billion tonnes of fertile soil each year, that is the equivalent of 3.4 t/year/person on earth. José Graziano da Silva, Director General of FAO, notes, “It can take up to 1,000 years to form one centimetre of soil (1 tonne per hectare per year), and with 33 percent of all global soil resources degraded and human pressures increasing, critical limits are being reached that make stewardship an urgent matter.” Urbanisation led to loss of some 705,000 hectares of British rural land between 1945-1990, and building is now leading to loss of some 1400 hectares per year from UK agriculture. Globally, some 2 hectares of soil per minute (300 acres an hour!) are sealed over by expanding cities. Furthermore, although some undergrazing by sheep is possible, covering productive fields with solar panels exacerbates this loss of productive land – notwithstanding their sound short-term business sense given recent UK energy grants, and the appeal of generating renewable energy…
Soils are reckoned to contribute some 25% of the world’s biodiversity, with their myriad micro-organisms (more than the global human population of 7.25 billion in a thimbleful of normally fertile loam) plus the larger contributors such as the humble yet noble earthworm. Our forebears were not far out in reckoning the potential productivity of a pasture in terms of meat, wool and milk being proportional to the population of earthworms within its underlying soil! The International Union of Soil Sciences reckons that there are over 100,000 different types of soil – that’s biodiversity indeed! The hefting of particular breeds of sheep – and of types within them – to particular soils and their associated climates contributes hugely to the rich agricultural biodiversity within the UK; not forgetting our rich heritage of crop ecotypes such as Suffolk’s Kersey wild white clover or Kent’s variant of the same species. In this connection, I have just read and commend to members a superb book Counting Sheep: a celebration of the Pastoral Heritage of Britain by Philip Walling (2015, Profile Books, London, 266 pp.). I don’t have shares in the book or the publisher!!
As might be expected, we have many members cherishing and striving to care for their soils while obtaining optimum productivity from them by means of correct cultivation, appropriate planting techniques, strategic use of cover cropping and suitable crop rotation. I was taught 3 great principles of soil management by my late great Professor E. Walter Russell at Reading, which I have sought to pass on to others and to apply:-
1. Maintain Soil Cover as much as possible; especially with loose, light soils on erodible sites
2. Keep the nutrients in; maintaining vigorous nutrient cycles and pursuing nutrient management plans
3. Keep the weeds out; this is easier said than done in the case of such recalcitrant ones as blackgrass!
Conservation Farming – CF is an overall soil management system that is gaining ground worldwide (Indo-Gangetic Plain, Southern Africa, Brazil and elsewhere in South America, North America, Australia, as well as in parts of continental Europe, and here in the UK). It is also called Conservation Agriculture – CA, and often historically called Minimal Tillage or Reduced Cultivations in the UK, which some members have assiduously practised. However, CF has a set of associated practices that are combined together:- it links reduced early cultivation, seed and nutrient placement, mulching and rotations. Its efficacy lies not only in saving the operational/energy costs of traditional cultivations (by moving only some 15% of soil by contrast with overall tillage) but also in conserving moisture which can substantially increase yields in dry seasons and drought-prone climates. In such situations, farmers have doubled or even trebled yields quite commonly with proper CF adoption where ample nutrition is maintained using composts, manures and fertilisers.
CF offers a disciplined but adaptable management approach. CF benefits of Water and Organic Matter Conservation combined with soil structural improvement are cumulative but rely on enough previous crop yield and thus proportionate root activity and enough healthy mulching matter residues to use for the next crop. Minimal cultivation tends to change weed ecology needing more initial in-crop weed control and maybe more perennial, especially grass weed control later.
Professor John WibberleyShare this
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