The Phosphorus Fertilizer Dump

Adding phosphorus fertilizer to soil to correct pH or nutrient balance is commonly done by farmers and gardeners. But it’s normally done in small to moderate amounts to boost the P needed in NPK to the level needed by whatever you’re growing. Unless you happen to have tropical soil. Then you need lots of it. So much, in fact, that it’s, well… kind of insane.

Phosphorus Fertilizer Abuse

It calls for input equal to output – every time you plant. Why? Because the soil makeup locks up phosphorus making it unavailable to the crop. So, in a place like Brazil a single soy bean field consumes exorbitant amounts of rock phosphate annually.

This would be considered “marginal land” in the US, because it’s inhospitable and has undesirable characteristics. Not being able to maintain macro nutrient value with a reasonable amount of inputs is definitely undesirable, without which its totally inhospitable to commodity crops. It’s economically inefficient production that’s only possible on a costly, highly unsustainable life support system. It’s also a really wasteful approach to feeding the world, because:

  1. Agricultural phosphorus fertilizer is made from rock phosphate.
  2. The rock is found in only a handful of places globally.
  3. It’s a non-renewable resource.

Even so, Brazil has been industrial farming soy for feed exports to Europe and China for decades. The phosphorus poured on cropland there likely was imported from Morocco or the Sahara to begin with, where over 70% of the world reserves are located. They go through 1-4 million metric tons of it a year to produce a big portion of the world’s soy bean supply, and 50% of it is forever lost, tied up in the soil. In comparison, North America uses 2 million metric tons for all crops annually. One would think that over the course of 30 years some reserve would have built up in the soil, but that’s not the case.

Soybean Harvest: Mato Grosso, Brazil Farm

Courtesy of La Croix (Paulo Whitaker/Reuters)

It’s grand that a state with some of the poorest soil in a developing nation can become “an global agricultural powerhouse” – but not when it’s this unsustainable in terms of soil inputs. Successful Farming reports that 185,000 hectares of pasture were converted to soybean production for the 2015/16 crop season in Mato Grosso alone, the state with the worst soil in the country. Yet, agricultural scientists from the US are currently studying the situation, and questioning the rationality of increasing industrial farming on tropical soils with their excessive phosphorus consumption. Brazil may be the world’s #2 producer of GMO crops, but at what cost to the well being of the rest of the world? There is only so much phosphate rock.

Not only is this absurd, it will cause all manner of psychological, economic, and political unrest. This practice could create drastic food insecurity issues worldwide, not to mention rising costs of biofuels and pharmaceutical crops due to production costs will be passed on to consumers. Further expense increases would be felt in other business and consumer pursuits connected to the soil – namely home gardening, one of the all time top pastimes on the planet. The price of phosphorus to grow anything will skyrocket. As with other such situations, it’s very likely that consumers who need this resource will pay much more per ton than farmers.

Scientists call this predicted hike in fertilizer prices “the P tax” – because it takes a pound of phosphorus fertilizer to grow a pound of phosphorus-rich grain on tropical soil. Just this week the University of Vermont announced, “The P tax cometh” on the science news site, EurekAlert. And its not just Brazil… 10% of global farmland has this phosphate hungry soil. It exists in the places that there’s a big push to expand industrial farming, like most of South America and Africa.

Drivers of this system think it’s all good, you just dump on more fertilizer. Never mind that it’s like a bottomless pit. Currently suggested solutions include stopping food waste, figuring out how to extract the lost P out of the soil it’s bound to, and using human sludge.

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Tammy Clayton

Contributing Writer at Garden Culture Magazine

Tammy has been immersed in the world of plants and growing since her first job as an assistant weeder at the tender age of 8. Heavily influenced by a former life as a landscape designer and nursery owner, she swears good looking plants follow her home.