Perennial grain facts for kids

A perennial grain is a special type of grain crop that lives and produces food for more than two years. Most grains we eat today, like wheat, rice, and corn, are annuals. This means they grow for only one season before they are harvested and die.

Many fruit and nut trees are perennial plants, meaning they live for many years. But all the main grain crops used in large-scale farming today are annuals. Scientists from different countries believe that creating perennial versions of our grain crops could make farming much more sustainable and better for the planet.

Why Perennial Grains Matter

In 2005, a big report from the United Nations said that farming is the "biggest threat to nature and how ecosystems work." Perennial grains could help reduce this threat. Here's why:

• Most farmland is used to grow grains like cereals, oilseeds, and legumes. These grains, including wheat, rice, and corn, provide over 70% of the food calories humans eat.
• All these grains are currently annual plants. They are usually planted in soil that has been tilled, or dug up, often.
• Digging up the soil often can cause it to be lost or damaged. This is called soil degradation.
• This creates a problem: how we grow food now can harm the ability to grow food in the future. Perennial grain crops could solve this because they don't need the soil to be tilled every year. While no-till farming helps, perennial plants protect the soil the most.

Developing Perennial Grains

Today's farming mostly uses annual plants. Growing these plants often requires a lot of tilling and chemicals like pesticides and fertilizers. This can lead to problems like soil erosion, too many nutrients in water (eutrophication), and using too much fossil fuel.

Developing perennial grains could make farming much more sustainable. Unlike annual plants, perennial plants have deep, long-lasting roots. A perennial farming system would not need as much tilling. It could also reduce the need for chemicals, improve soil health, and help store carbon in the soil.

Farmers have been growing annual crops for almost 10,000 years. But no commercial perennial grains have been developed yet. It's not clear why perennial grains weren't grown alongside annuals when farming first began.

One reason might be that wild annual plants were easier to grow at first. They often produced more seeds in a single year than wild perennial plants. Annuals naturally put a lot of energy into making seeds because their survival depends on it. Perennials, however, have to balance making seeds with surviving through winter, so they tend to produce fewer seeds each year.

Also, annual plants grow faster from seed to seed. This made it easier for early farmers to choose the best plants to grow over time. Early farming also involved tilling the soil to clear fields for the next year's crop. This practice of tilling isn't good for perennial grains, which need to stay in the ground. Once annual grains became popular, there was less reason to try to grow new perennial grains.

However, scientists believe that these early challenges don't mean high-yielding perennial grains are impossible. Perennials might actually do better in later years because their roots are already established. This means they can get more water and nutrients from the soil, possibly reducing the need for fertilizer. Even if perennials put less energy into seeds, their overall yield might still be good because they can get more resources and grow larger.

How Scientists Create Perennial Grains

Scientists are working hard to speed up the process of creating perennial grains. Serious efforts began in the 1980s, led by Wes Jackson and The Land Institute in Kansas. There are three main ways scientists are trying to develop new perennial grains:

• Making annual plants perennial.
• Starting from scratch with wild perennial plants.
• Using modern genetic science.

These methods can be used together, but each has its own challenges.

Making Annuals Perennial

One way is to mix existing annual crops with their wild perennial relatives. The goal is to keep the good traits of the annual grain, like high yield, while making the plant live for many years with strong, deep roots.

However, plants created this way are sometimes unable to reproduce. Also, the traits that make a plant perennial are often controlled by many genes. This means it's hard to transfer all the necessary genes from the wild perennial parent to the new hybrid plant.

Starting with Wild Perennials

Another way is to find wild perennial plants and then choose the best ones to grow. Scientists then use artificial selection to improve traits important for farming. These traits include high yield, seeds that stay on the plant until harvest, seeds that are easy to remove from their husks, and plant height.

Scientists at The Land Institute have created guidelines to help choose which wild perennial species have the best chance of becoming good crops. They also guide which traits to focus on when breeding.

A big challenge with this method is that wild perennial grains naturally produce very low yields compared to our farmed annuals. So, a lot of breeding work is needed to make them good enough for commercial farming.

Using Genetic Methods

Modern genetic science can also help. Scientists can use methods to predict plant traits by looking at their genes. This helps them choose the best young plants earlier, saving time and resources.

Scientists can also use genetic modification to add or change specific "domestication genes" in perennial plants. These genes are known to affect traits important for farming and have been found in annual crops. Scientists are finding that many similar genes also exist in perennial species.

Right now, using genetic methods is limited because the genes of many wild perennial plants haven't been fully mapped. Also, the methods for changing genes aren't perfect for all these plants yet. But genetic techniques are improving quickly and will likely be very helpful in developing perennial crops in the future.

Benefits of Perennial Grains

Scientists have found many good things about perennial grains:

• Longer growing season: Perennial plants usually start growing earlier in spring and stay alive longer in autumn than annuals. This longer growing season means they can capture more sunlight and rainfall. For example, in Minnesota, annual soybeans start growing in June. But perennial alfalfa is already ready for its first harvest by then.
• Deeper roots: Plants that live a long time usually have bigger, deeper root systems than short-lived plants in the same area. Deeper roots let perennials reach more soil each year. This larger soil area also means more water is stored for times without rain.
• Better use of soil nutrients: Less nitrogen from fertilizer is lost under perennial crops like alfalfa compared to annual crops like corn. Wild perennial grasses have been known to produce good hay for 75 to 100 years without needing fertilizer. This is likely because their larger root systems and the tiny living things in the soil use nutrients much more efficiently.
• Sustainable farming on difficult land: For many poor regions, growing annual grains might not be sustainable because of serious erosion. Perennial crops are better for these areas. Grains provide more food security than other crops like forage (animal feed) or fruit because they can be eaten directly by humans and stored for winter or dry seasons.
• Less soil erosion: Perennial plants of all kinds grow thick root systems that hold soil in place. This prevents soil from being washed away by water or blown away by wind. When water runoff slows down, it has more time to soak into the ground.
• More wildlife: Slower water release into streams helps keep water levels steady. This leads to more fish, amphibians, waterfowl, and mammals that depend on a consistent water source.
• Fewer weeds: Perennial grains can reduce the need for tilling and weed-killing chemicals.
• Healthier soil: Perennial grain crops may help good tiny living things in the soil grow. The frequent digging of soil for annual crops can harm these helpful soil organisms.
• Store more carbon: It's thought that perennial grains might store more carbon in the soil. This helps fight climate change.

Possible Challenges

There are also some challenges with perennial grains:

• Not a quick fix for food security: Perennial grain crops are still new. It might take many years before they produce as much food as annual grains.
• Harder crop rotation: It's possible to rotate crops with perennial systems, but the whole cycle will take longer. For example, a perennial hay crop like alfalfa is often rotated with annual crops after 3-5 years. This slower rotation could allow more pests or weeds to build up.
• Can use up soil nutrients: In soils with low organic matter and no tilling, crops with large root systems might use up almost all the nitrogen and phosphorus in the soil. This can make the plants less productive unless fertilizer is added.
• Impact on water: Perennial plants might use more rainfall each year than annual plants. This could cause water levels in the ground to drop or reduce water flowing into rivers.
• Less nutrients for farms downstream: If many annual crops are replaced with perennials, it could reduce the amount of soil and dissolved nitrogen flowing downstream. Farmers in those areas might currently rely on these natural nutrient inputs. However, other areas could benefit from cleaner water.
• More pests: If fields are not left bare for part of the year, populations of rodents and insects might grow. Burning the leftover plant parts of perennial grains could reduce these pests, but burning might not be allowed in some places. Also, pests living underground would survive burning, while tilling usually disrupts their homes.

Perennial Grains You Can Find

Kernza, a type of intermediate wheatgrass, has been developed as a grain crop since the 1980s. Since 2001, Dr. Lee DeHaan at The Land Institute has led its development. He gave it the trademarked name Kernza in 2009.

Recently, work on Kernza has grown rapidly. More than 25 lead scientists across three continents are working on it. This international team has found new ways to grow it and greatly improved traits like how well the seeds stay on the plant, seed size, and yield. This means Kernza can now be grown and sold on a small scale.

Researchers hope that Kernza, as the first perennial grain crop grown across the northern United States, will help change farming. They want croplands to do more than just produce food, like also providing benefits for the environment.

The Land Institute created the Kernza trademark to help identify intermediate wheatgrass grain that is certified as a perennial using the most advanced types of T. intermedium seed.

Another example is perennial rice 23 (PR23). It's used in a new rice farming system that doesn't require tilling the soil.