Here’s new evidence that fertilising grasslands can make them less stable. Therefore, fertilised grasslands might become more vulnerable to climate change. This is a serious matter in our hungry world.
Here’s the science. This research was led by Andy Hector at Future of Food, also called the Oxford Martin Programme on the Future of Food. ‘Here we analyse diversity–stability relationships from 41 grasslands on five continents and examine how these relationships are affected by chronic fertilization, one of the strongest drivers of species loss globally.’
Fertiliser can make land and water over-rich (eutrophic). Prof Hector’s team weren’t surprised to find that eutrophication robbed land of biodiversity, as often seen before. But they were surprised, in a bad way, to find that fertilised land lost stability in its production of plant material (biomass). This started to happen very soon, even before species disappeared.
The fertilised grasslands got extra plant nutrients, of course. That increased productivity in the short term. But as each dose of fertiliser was used up, productivity fell again. At the same time fertilised grasslands lost biodiversity. So plant species couldn’t balance each other’s productivity as much as they’d usually do.
Two changes during the year: nutrient levels fluctuating, and plant species not present to balance each other. In a world of changing climate, this doesn’t bode well for food security.