Potato Review

36 POTATO REVIEW MAY/JUNE 2023 FERTILISATION A natural resource that’s not unlimited Phosphate used by agriculture is from a non-renewable source that is gradually being depleted, while a high percentage bypasses crops and is found in waterways. Simon Fox, CEO of biostimulant provider Optiyield, explains. T HE Guardian recently ran an article highlighting the worldwide issue that scientists are referring to as ‘phosphogeddon’, its impact on fertiliser stocks and the knock- on e ects on world food supplies. It is imperative to understand how phosphate is supplied, e ectively used or wasted, not simply for growers’ bottom line, but for the continued ability for humans to feed themselves. Agriculture must acknowledge and fully understand three facts about the phosphate it uses to avoid ‘phosphogeddon’. Only through this greater understanding can we start to make better and more sustainable choices in our use of additional phosphate applications. Phosphorus used on farm today and consumed in food we eat is mined from a few sources of phosphate rock. is is unsustainable and by some estimates, there could be as little as 50 to 100 years’ resource left, especially if we continue to consume it at the current rate. In fact, 70% of the world’s phosphate supply is controlled by four countries: China (39%), Morocco (17%), the US (10%), and Russia (6%). With supply geographically limited, it leaves the market exposed to massive uctuations in costs and supply as a result of political disputes, trade wars and escalating fuel prices. Since 2020, the prices of both phosphate rock and fertiliser have increased by around 400% and continue to rise. Phosphate E ciency Phosphate e ciency refers to increased crop health and the additional yield gained from supplementary applications of phosphate, or rather the lack of it. ere are a number of possible reasons for inadequacies of phosphate fertiliser recommendations and applications. ey should encourage the industry to question not only the volumes being applied, but the methods of analysis and recommendation that lead to this. rough the results of continued research and development of soil nutrient analysis methods, greater understanding of nutrient interactions/ interdependencies and plant physiology should encourage the industry to question RB209. Developed in the 1970s and based on research from earlier in the 20th century, a review of the assumptions it’s based on and the recommendations it produces is long overdue, if for no other reason than the good management practice of ‘reviewing procedures’. Is it still t for purpose in today’s environment? e RB209 philosophy of “topping up” soil reserves to meet a certain level is surely not only outmoded, but wasteful and potentially unethical in leading to higher levels of pollution risk. Phosphate Waste Phosphorus runo from farms contributes to widespread water pollution. Admittedly most is not from agriculture. It’s estimated that 59% of nitrates (ADAS, 2007) and 26% of phosphates (White and Hammond, 2006) in English waters are of agricultural origin. Of the 26% of phosphate that comes from agriculture, particulate phosphate from tilled land accounts for 75-95% in the UK’s waterways. is comes from phosphates sorbed by soil particles and organic matter which is eroded during runo