Potato Review

12 POTATO REVIEW MARCH/APRIL 2020 CUPGRA 2019 CONFERENCE Building resilience B y changing to a min-till strategy, costs can be reduced as fewer tractors are needed, but more work is needed to understand the consequences for wildlife, he said. This implies the need to better understand soil health and the impact of crop rotations, and the impacts of changing to min-till or no-till regimes. These can help concentrate the carbon in the top five centimetres of the soil, which is exactly where it is required. “Unfortunately, we have been unable to discover whether it increases the overall carbon bank of a particular soil, so switching tillage is not necessarily a solution to carbon banking in the soil.” Reducing runoff and erosion is also crucial, and soil used for growing potatoes is subjected to a lot of working, both at planting and when lifting. “Eighty per cent of the erosion of our soils comes from tram-lines, so water runs off the surface and carries the soil with it,” said Dr Leake. To help alleviate this problem, he recommends low-pressure tyres which create less compaction, so Respecting the land Dr Alastair Leake, Director of Policy & the Allerton Project for the Game &Wildlife Conservation Trust, has been undertaking research which involved measuring carbon emissions, earthworms, cultivation costs and yields. drainage is less compromised. He went on to speak about the old Norfolk rotations, which had restorative phases alongside exploitative phases, followed in sequence, saying growers had moved away from this towards “endlessly exploitative rotations”. He suggested government support for the re-introduction of grass, to help re- build organic carbon and stability. “We have been cutting and mulching, and letting the worms pull down the organic matter, and this has been working really well.” Crops do not appear to be suffering in quality or yield, costs of fertiliser and spraying have gone down, and soil structure is benefitting, he added. Regenerative cropping, such as using cover crops where suitable, planting headlands with low productivity with flower mixes, and the use of sheep to graze land over winter, so that soils can become more resilient. “We need to keep our focus on respecting land and, where possible, harvesting when conditions are at their best so they are in a drillable state for the next season.” Soil used for growing potatoes is subjected to a lot of working. The measurement of earthworms, along with carbon emissions, has formed part of Dr Leake’s team’s research.