Soil and Fertilizer

The Downside of Fertilizers

In a belated celebration of Earth Day, this fourth in our April series on soil focuses on the negative side effects of various soil amendments and on hopeful signs we can do better. We are all familiar with the phenomenon of eutrophication, algal blooms that overwhelm waterways when too much phosphorous runs off from agricultural operations. Nitrogen fertilizers also can easily volatilize, leading to emissions of nitrous oxide, which has hundreds of times the warming potential of CO2. However, as the second article below details, the exploitation of these resources has led to human rights violations as well as environmental degradation. The example of the Rich Earth Institute offers hope that we may be able feed a growing population without destroying the planet in the process.

Reducing nitrogen use key to human and planetary health: study

The use of chemical fertilisers helped fuel the four-fold expansion of the human population over the last century.

Better management of nitrogen-rich fertilizers through alternating crops, optimizing use and other measures can yield huge environmental and health benefits, but must boost food production at the same time. Reducing nitrogen pollution from global croplands is a “grand challenge,” the group of international researchers said in a study published in Nature outlining a dozen urgently-needed reforms.

The intensive use of chemical fertilizers helped fuel the four-fold expansion of the human population over the last century, and will be crucial for feeding 10 billion people by 2050. But the bumper crops of what was once called the Green Revolution have come at a terrible cost. Today, more than half the nitrogen in fertilizers seeps into the air and water, leading to deadly pollution, soil acidification, climate change, ozone depletion and biodiversity loss.

Earth’s natural “nitrogen cycle” has been massively imbalanced by the use of some 120 million tons of chemical fertilizer each year. Less than half of that input is actually absorbed by plants, with the rest seeping into the environment and causing a constellation of problems. Researchers led by Baojing Gu, a professor at Zhejiang University, analyzed over 1,500 field observations from croplands around the world and identified 11 key measures to decrease nitrogen losses while still enhancing crop yields. One such method is crop rotation where a variety of crops are planted on the same plot of land, optimizing the flow of nutrients in the soil. The benefits of slashing agricultural nitrogen pollution are some 25 times higher than the implementation costs of about $34 billion, they found.

Phosphorus Saved Our Way of Life—and Now may End It

Bou Craa conveyor belt from the phospahe mine. Photo from flickr, taken on 11 March 2013 in Western Sahara near Laayoune Marsa Boujdour. Photo by jbdodane.

Like nitrogen, phosphorous soil amendments were an important part of the Green Revolution that enabled us to feed so many more humans. And like nitrogen amendments, using phosphorous as a soil amendment comes with unanticipated costs. Writing in The New Yorker, Pulitzer Prize winning author Elizabeth Kolbert details the sordid colonial history of guano exploitation in Peru and South Pacific Islands. Once the accumulated bird poop of thousands of generations had been consumed by farmers in Europe and the US, and the nesting sites of many birds destroyed, science stepped in to invent chemical ways to extract nitrogen from the atmosphere and phosphorous from rock. As Kolbert writes: ” The longest conveyor belt on earth begins in the town of Bou Craa and runs for sixty miles across Western Sahara to the port city of El Marsa…. The conveyor carries phosphorus-rich rock, which is mined in Bou Craa and then shipped from the coast to places like India and New Zealand to be processed into fertilizer. The mine, and indeed the vast majority of the rest of Western Sahara, is controlled—illegally, by most accounts—by Morocco, which possesses something like 70% of the planet’s known phosphorus reserves.”

The political fragility of Western Sahara is just one worrying aspect of the future of phosphorous use. Phosphorus is critical not just to crop yields but also to basic biology. DNA is held together by what’s often called a “phosphate backbone”; without this backbone, the double helix would be a hash. Isaac Asimov described phosphorus as “life’s bottleneck.” What distinguishes it from other elements that are essential to life—carbon, say, or nitrogen—is its relative scarcity. The atmosphere contains almost no phosphorus. Phosphate-rich rocks, meanwhile, exist only in limited quantities, in certain geological formations. China holds the world’s second-largest reserves—these are less than one-tenth the size of Morocco’s—and Algeria the third-largest.

There are parallels between the exploitation of guano in the 19th Century and phosphorous in the 20th Century. The Bou Craa mine is the main reason Morocco illegally invaded Western Sahara in 1975. The descendants of tens of thousands of refugees from Western Sahara are still living in refugee camps in Algeria today. Meanwhile, phosphorous use in agriculture has led to increasing large “dead zones” in waterways and oceans around the world. Harmful algal blooms caused by phosphorous leaching into waterways can also contaminate water supplies and cause illness. Scientists warn that, as nutrient loads continue to grow and the planet heats up, the problem will only get worse.

The Rich Earth Institute in Brattleboro, Vermont, works for “a world with clean water and fertile soil achieved by reclaiming the nutrients from our bodies”.  The Institute encourages donations of urine from the local community. Arthur Davis, who directs Rich Earth’s Urine Nutrient Reclamation Program, explains, “Around 60% of the phosphorus we excrete comes out in our pee.” Peecycling can cut down on the amount of conventional fertilizer that the farmers purchase. (Urine contains not only phosphorus but also large amounts of nitrogen and potassium.) At the same time, it keeps nutrients out of the sewage system and, by extension, it is hoped, out of Vermont’s waterways. It may also help to avoid some of the human and environmental rights violations associated with the historical exploitation of phosphorous.

Credit: Unsplash/CC0 Public Domain

(See also: Phosphorus shortage could affect worldwide crop yields)

Biodiversity Climate Change Conservation Gardening Pollinators, Molluscs and Other Invertebrates Sustainable Living

2023 February Conservation Update

In this post, a fascinating DNA sampling technique; conflicting news about human impact on animal populations; and a cute story about newt rescues in California. We also look at how rising temperatures due to climate change may damage animals; and a study that shows protected areas aren’t designed to protect invertebrates. It turns out we’ve been putting those anti-bird-strike decals on the wrong side of the window; and we look at where your plants come from.

Postcard-sized poo sample collection cards offer an affordable alternative to more cumbersome methods of collecting and storing the genetic information in dung. The cards do not need to be refrigerated and maintain viable DNA for months after collection. Credit: Fred Zwicky

Streamlined DNA for wildlife conservation

A team from University of Illinois at Urbana-Champaign has come up with a new way of sampling DNA that allows scientists to capture genetic information from wildlife without disturbing the animals or putting their own safety in jeopardy. The protocol, tested on elephant dung, yielded enough DNA to sequence whole genomes not only of the elephants but also of the associated microbes, plants, parasites and other organisms—at a fraction of the cost of current approaches. The researchers report their findings in the journal Frontiers in Genetics.

A family of urban raccoons. Photo by Jon Last.

Can urban neighborhoods be both dense and green?

The British Ecological Society reports on a new study from The Nature Conservancy (TNC) that explores how we can make our cities work better for people and wildlife.  By analyzing existing approaches, as well as highlighting cities already creating the right balance of people and wildlife, the study pioneers an alternative method of city design that allows for the accommodation of both denser populations as well as wildlife. “This needn’t be a zero-sum game,” explains senior author and TNC lead scientist for nature-based solutions, Rob Mcdonald. “Having denser cities doesn’t automatically mean less space for nature.”

But, while animals may be able to co-exist happily with humans in urban areas, another study highlights how human incursions into natural areas can disturb wildlife.

Researchers placed camera traps along hiking trails in Glacier National Park during and after a COVID-19 closure. They found that 16 out of 22 mammal species changed the way they accessed areas when humans were present. Credit: Mammal Spatial Ecology and Conservation Lab, Washington State University

Human recreation changes wildlife behavior

Even without hunting rifles, humans appear to have a strong negative influence on the movement of wildlife. A study of Glacier National Park hiking trails during and after a COVID-19 closure adds evidence to the theory that humans can create a “landscape of fear” like other apex predators, changing how species use an area simply with their presence. Researchers found that when human hikers were present, 16 out of 22 mammal species, including predators and prey alike, changed where and when they accessed areas. Some completely abandoned places they previously used, others used them less frequently, and some shifted to more nocturnal activities to avoid humans. The study was published in the journal Scientific Reports. The researchers had also expected to find an effect known as “human shielding,” when human presence causes large predators to avoid an area, providing opportunity for smaller predators and perhaps some prey species to use an area more frequently. In this case, they found this potential effect for only one species, red fox. The foxes were more present on and near trails when the park was open–perhaps because their competitors, coyotes, avoided those areas when humans were around. While the influence of low-impact recreation is concerning, the researchers emphasized that more research is needed to determine if it has negative effects on the species’ survival.

Credit: Unsplash/CC0 Public Domain

Animals at risk from heat waves

More than 40% of all land vertebrates may be subjected to extreme heat events by 2099 under current maximum estimates of future global temperatures, according to a study published in Nature. Prolonged exposure to high temperatures could be dangerous for the future of many species across the globe. Extreme thermal events, a period in which the temperature greatly exceeds a historical threshold, have increased in frequency compared to historical records, exacerbated by climate change caused by human activity. Recurring periods of extreme heat affect wildlife and are associated with increased psychological stress, reduced reproductive output and decreased population sizes, meaning that the continuation of these temperature spikes would pose a substantial threat to future biodiversity.

A ‘Big Night’ for Newts

The New York Times has a heart-warming story about the heroic work of the northern California Chileno Valley Newt Brigade in rescuing amphibians that might otherwise become roadkill as they cross a road from their breeding grounds and their burrows. But newt rescue is just a short-term solution. The group is also fundraising for road modifications that will allow the newts to pass safely underneath.

Black swallowtail on thistle at New Life Retreat. Photo by Carol English.

Protected areas fail insect species

Insects play crucial roles in almost every ecosystem—they pollinate more than 80% of plants and are a major source of food for thousands of vertebrate species—but insect populations are collapsing around the globe, and they continue to be overlooked by conservation efforts. Protected areas can safeguard threatened species but only if these threatened species actually live within the areas we protect. A new study in the journal One Earth found that 76% of insect species are not adequately covered by protected areas.

Northern cardinal. Photo by Jon Last.

What we know about bird window strikes is inside-out

New research from William & Mary published in PeerJ reveals that decals intended to reduce incidents of bird window strikes—one of the largest human-made causes of bird mortality—are only effective if decals are placed on the outside of the window. Researchers found that the patterns on the films and decals placed on the internal surface of windows do not reduce collision because they may not be sufficiently visible to birds.

A fynbos bouquet from South Africa. Credit: Juan Pablo Moreiras/Fauna & Flora

Where do your plants come from?

Tim Knight of Fauna and Flora International asks if we ever ask ourselves where all our garden plants come from? The local garden center or superstore isn’t the answer. Take bulbs, for instance. There’s a common understanding that most bulbs come from The Netherlands. In fact, most wild tulips hail from the mountainous regions of Central Asia. Kyrgyzstan, Tajikistan, Kazakhstan and Uzbekistan—countries not widely recognized as havens of biodiversity—harbor the lion’s share of species. Turkey is also one of the richest areas in the world for bulbs, including familiar garden favorites such as snowdrops, crocuses, cyclamens and, yes, tulips too. It’s easy to forget that these wild relatives are the original source of the endless varieties and hybrid forms that grace our gardens and fill our flower vases. And that they face a variety of threats, from overharvesting and habitat loss to climate change.

Houseplants come from all over, including the popular Monstera, which is an epiphyte, growing on trees in its native South America. With one notable exception, bromeliads are found only in Central and South America. A single species—endangered and known only from Guinea—occurs in West Africa. Most bromeliads are also epiphytes, but the one that we’re most familiar with—though you may not think of it as a bromeliad—grows on the ground and produces one of our most popular tropical fruits, the pineapple.

White Christmas cactus. Photo by R. Last.

Cacti may be famous for their tolerance of extreme heat and drought—and plummeting temperatures at night—but they’re not confined to hotspots like the American Midwest and Mexico. Of the roughly 2,500 species of cactus in the world, quite a few thrive in rainforests or cooler climes. The Christmas cactus is native to damp forest in the coastal mountains of Brazil.

The article goes on to detail the origins of orchids (pretty much from every continent, except Antarctica); where cut flowers come from; and what makes the fynbos in South Africa so special. Mr. Knight concludes by urging gardeners to pay attention to the origins of plants they purchase and avoid those that come from unsustainable sources.

Food & Agriculture

2023 February Farming

Credit: Shutterstock

Better nitrogen management yields more than it costs

Better management on agricultural lands to reduce nitrogen losses to the environment costs only a fraction of what it provides. This could yield nearly $500 billion in societal benefits globally for both food supply and human health, ecosystems and the climate. And this at a net cost of nearly $20 billion. That’s according to a study published in the scientific journal Nature.

Skylark (Alauda arvensis), at the grassy edge of a small field. Cornwall, England. June. Credit: RSPB

Farmland bird populations rise with nature-friendly farming

In a study published in the Journal of Applied Ecology, researchers from the Royal Society for the Protection of Birds (RSPB) say a more strategic approach to wildlife-friendly farming schemes is required to recover England’s farmland bird populations after monitoring their responses to different agri-environment scheme implementation levels. The U.K. government has recently introduced a legally binding target to halt species abundance declines in England by 2030. However, tiered environmental management schemes have been in place on UK farms sometime. Higher tiered schemes devote an average of 11% of the farmland to bird-friendly measures, while lower-tiered schemes set aside an average of less than 4% of their land. This 10-year study measured changes in the abundance of farmland birds on land managed under bird-focused lower- and higher-tier agri-environment schemes, as well as land no bird-friendly farming initiatives. The results showed that when approximately 10% of a farm was devoted to bird-friendly farming practices under the higher-tier scheme, this benefitted over half of the farmland bird species in two of the three study regions. Although lower-tier provision generally failed to increase bird numbers, it helped to sustain populations of some species, which continued to decline in the absence of agri-environment support elsewhere. The second part of the study asked what proportion of the farmed landscape would need to be placed into higher-tier agreements to recover farmland birds by 10% over ten years. The answer was similar in the two regions—26% in the pastoral West Midlands and 31% in arable East Anglia. However, by targeting higher-tier agreements to farms that already hold higher numbers of priority farmland birds, this requirement drops to 17% and 21% respectively, which represents a significant cost saving. This is the first study to shed light on the amount of nature friendly farming that might be required to recover farmland birds at a landscape scale.

Sheep grazing at the Arnprior Solar Project. Photo by Chris Moore

Solar panels and sheep get along just fine

Pippa Norman writes in The National Observer about how farming and clean energy production can work together. Like many farmers, Chris Moore once doubted the practicality of solar panels and agriculture co-existing on the same land. He couldn’t quite believe the land would be productive while shaded by these large, metallic shields. About 12 years ago, a 200-acre solar farm sprung up in Arnprior and he passed it by on his daily commute. The more he looked at the grass growing beside and beneath the solar panels, the more it started to seem an ideal spot for a sheep pasture. His skepticism began to fade. The Arnprior Solar Project is one of the largest solar electricity sites in Canada, generating enough energy to supply about 7,000 homes. And for the past five years, it has also doubled as a summer home for hundreds of the couples’ ewes. It took Moore a long time to picture his sheep grazing in the shade of those solar panels. Ontario environmental regulations, farmers associations and farmers have, historically, been resistant to allowing land to be used for both agricultural and solar power. But Joshua Pearce, Western University’s John M. Thompson Chair in Information Technology and Innovation, was convinced that without a crop or animals, the shade of those solar panels was a missed opportunity. Pearce is an advocate and expert in the field of agrivoltaics — the dual use of land for solar electricity and agriculture. Allowing animals to graze is the most basic version. More sophisticated versions tailor the solar panel installations to the crop that grows underneath. “You shade the plant that you’re growing with a partially transparent solar cell. It provides a little microclimate underneath it, so it conserves water, and then you get more growth,” Pearce explained. Vertical or movable solar panel options allow for plants like corn or wheat to grow high or for tractors to manoeuvre around crops, Pearce added. Outside of fields, solar panels can also be attached to greenhouses roofs or potentially even floated on bodies of water.

(Thanks to Erwin Dressler for sharing the link to this story.)

Guy Singh-Watson Riverford, pictured at Riverford organic farm in Devon, began experimenting with hazelnut and walnuts trees after feeling guilty about how much he ploughed his fields for vegetable crops. Photograph: Joanna Furniss/Riverford

English farmers turning to cultivating nuts as climate heats

Helena Horton writes in The Guardian UK about one way farmers are adapting to warmer temperatures. Nuts are being grown more than ever by English farmers as the climate heats, making the products more economically viable, growers have said. Nut trees are also helpful for biodiversity on farms, improving soil health as their roots improve the ability and capacity of soil to absorb water, reducing the risk of wind erosion. Guy Singh-Watson has enjoyed his recent foray into growing nuts on his 150-acre Devon farm. He said they were easy to grow: “You don’t have to do anything, I spent 40 years trying to coax vegetables into life and they just die all the time, but hazels grow so well. There doesn’t seem to be any problem growing walnuts in our climate.” He has had success grazing cattle in the orchards, and now plans to grow kale among some of his hazel trees. England’s climate is heating up, with last year the hottest on record, with a long, dry summer. This is making many crops difficult to grow, and many farmers reported crop failures during the drought. Though they sometimes need irrigation when first planted, nut trees do well in warm weather and can survive dry summers. Singh-Watson said he had recently visited Piedmont in Italy, where hazelnuts are a major crop – it is home to Ferrero, the company that makes Nutella. Despite the hot, dry summer in Italy, the nuts were flourishing. The article also reports on the promising nut-growing experiences of a couple of other English farmers.

A row of field maples (Acer campestre) trellis grape vines, and are pollarded to harvest ‘tree hay’ fodder for livestock. Maize grows beside the row. The grapes are harvested to make wine. Source. Found on Shelterwood Forest Farm website.

European farms mix things up to guard against food-supply shocks

The EU is increasingly promoting mixed farming as a hedge against climate change and food insecurity. In just over a minute, this video explains what that means.