Potato Review

www.potatoreview.com POTATO REVIEW MAY/JUNE 2023 41 SOIL HEALTH ‘Build better soils to help with SFI funding’ Funding and crop growth rely on a good understanding, says expert G ROWERS will need to gain a better understanding of their soils to meet the new Sustainable Farming Incentive (SFI) ‘arable soils’ standard. Timac Agro Technical Manager, David Newton, says this knowledge will be key to accessing future funding, but also for supporting future crop growth. “ e SFI funding aims to encourage activities which improve soil health, but it can be hard to knowwhere to even begin,” he said. “Under the current guidelines, farmers and growers can receive £22/ha at an introductory level, or £40/ha at an intermediate level for the ‘arable and horticultural soils’ standard, so it’s well worth investing in your soil health.” David said as well as testing for soil pH and macronutrients (nitrogen, phosphorus and potassium), checks should b made on trace elements ans soil structure assessed at the same time, since the scheme requires a test for organic matter levels. It’s also important to understand your soil type, he stressed. “Understanding your soil type means understanding it’s advantages and challenges, how best to work with it and improve its health and biology,” he said. Soil type in uences structure and its consequent ability to retain nutrients and water, as well as its workability. Lighter, sandier soils can be more acidic and prone to leaching owing to their porous nature. ey can also have lower organic matter levels, which consequently a ects soil biology, David said. “On the other hand, heavier clay soils are more prone to compaction and poorer water drainage owing to smaller particle sizes and are heavier to work. However, often they are more fertile and retain organic matter more e ciently,” he said. David says crops require a host of essential nutrients for growth and requesting a more detailed soil analysis for nutrients, such as sulphur, calcium, manganese, copper, iron and boron, can help you predict any de ciencies and limitations to plant growth in the future. Encouraging soil biology to thrive is paramount to soil processes, such as the mineralisation of organic matter to provide nutrient availability for plants, he added. “Using a soil conditioner, such as Humistart+, can help provide a better environment for fungi and bacteria to thrive, in turn encouraging rapid break down of organic matter and the release of nutrients,” David said. Taking steps to better understand your soils and carrying out practices which enhance soil biology and fertility will lead to maximised nutrient use e ciency, he advised. “Under the current circumstances where the cost of fertiliser is still high, improving your nutrient use e ciency is paramount, as well as reducing risks such as soil run- o and leaching – an ultimate goal the SFI standards are wishing to achieve.” Reviewing past season Looking back at last season with robust soil and crop analysis data is a good means of determining how to improve performance for the coming season with insightful management decisions, according to Sajjad Awan of agronomic analysis provider NRM. Regular soil testing has always been a part of good farm practice and was recently included as legislation in the Farming Rules for Water. Taking this further and analysing soils in conjunction with plant tissue, harvested crops, and inputs, can help growers and advisors to better understand their nutrient status and benchmark against other farms, Sajjad advised in a recent submission for PDA (Potash Development Association). When it comes to soil nutrient analysis, the starting point must be to understand the pH of the soil, he stressed. “Incorrect soil pH can have a big impact on nutrient availability, particularly phosphate, however it is surprising howmany soils still show up as being too acidic and in need of rectifying. In 2021/22, the samples analysed by NRM showed that soils ranged from pH 4.8 right up to pH 9, although the median of all results was close to pH 7. 25% of soils were below the optimum of 6.5 for arable soils and therefore in need of lime,” he said. e Professional Agricultural Analysis Group (PAAG) data has regularly shown the proportion of UK soils that fall below the target levels for phosphate and potash, and NRM’s data from last season is no di erent. For phosphate, whilst the median result came in at the top of index 2 (23.2mg/l), the spread ranged from just 4mg/l (low index 0) right up to 56.6mg/l (index 4). Nearly a quarter of samples came in below an index 2 therefore below the target for optimal uptake by potato crops. “As with phosphate, the potash samples showed that the median result was at the target level of index 2- (154.7mg/l). However, unlike the P samples, a greater proportion were measured at, or below, index 1 (29%) and therefore at risk of potassium de ciency. is could reduce crops’ yield potential, especially with the recent history of dry weather patterns throughout spring and summer,” said Sajjad. For magnesium, the median value was 2, which is the target level, and although 27% of samples were measured above the target index, there were still nearly a quarter of the results that were at index 1 or belowwhich would bene t frommagnesium applications for most crops. is is not surprising, econsidering the large increase in the cost of fertiliser last season. More concerning could be the results of future soil samples, where applications may have been reduced or omitted, Sajjad said. “Soil analysis is one piece of the puzzle but is not the only measure that is worth considering. e basic principles of P&K nutrition in the UK revolve around ensuring that the soils contain su cient nutrient (and the correct pH to ensure optimal availability of these nutrients) to provide crops with adequate daily quantities through the season to meet the peak uptake requirements. “Although this is the theory, every soil will work slightly di erently, and no two seasons are the same. Just because a soil is at the target index, does not necessarily mean it is able to access su cient quantities due to variables such as soil characteristics (texture, moisture content, temperature); root characteristics (depth, length, architecture, health, mycorrhizal associations) and crop species.”