Scientists Scrutinize Elements Flowing Through Food Trade

May 09, 2023

By Sue Nichols

Nitrogen and phosphorus are two elements essential for all life on earth yet how much and where are crucial to global sustainability. An international group of scientists show how the two elements flow through the booming global food trade and how to protect both the environment and markets.

The two elements are abundant in fertilizer, soil and manure. In Nature Communications, scientists from Michigan State University Center for Systems Integration and Sustainability (MSU-CSIS) with colleagues across the world explore what impacts as global diets change and crops and animal products are traded increasingly. Flows of nitrogen within the global food and animal feed trade increased by eightfold during 1961–2010, accounting for one-third of the total nitrogen produced in the world then. Phosphorus flows in global agricultural trade increased by 750% in that time period.

But, researchers note, the flows of nitrogen and phosphorus haven’t been studied together at a global scale.

“Examining the global flows of nitrogen and phosphorous simultaneously can help compare their effects across the world,” said co-author Jianguo “Jack” Liu, Rachel Carson Chair of Sustainability and CSIS director. “The findings can be useful to enhance the benefits and reduce the risks brought by agricultural trade flows.”

The group turned to the conceptual framework of telecoupling, which allows scientists an integrated way to look at how people and nature interact across the world and provides a new language to look at the big picture and at details simultaneously.

The group found that overall, the growth of global trade saved on nitrogen and phosphorus, the finer points demanded attention. They also noted that countries who lacked efficiency in production would do well to improve technology that would trim both the waste and pollution of the elements.

The work also explored virtual nutrients – a way to represent how the elements can move across trade because they were used in growing or producing the products. This perspective shows an oft-hidden environmental burden can be shifted to exporters. For example, the U.S. suffered pollution when the pork and chicken it produced to send to Japan resulted in 0.11 million tons of nitrogen leaking into the to the local environment.

“Physical and virtual nutrient flows in global telecoupled agricultural trade networks” was written by Xiuzhi Chen, Yue Hou, Thomas Kastner, Liu Liu, Yuqian Zhang, Tuo Yin, Mo Li, Arunima Malik, Mengyu Li, Kelly R. Thorp, Siqi Han, Yaoze Liu, Tahir Muhammad and Yunkai Li.

The work was supported by National Natural Science Foundation of China, The National Science Foundation, the National International Postdoctoral Exchange Fellowship Program, World Sustainability Award, Gunnerus Award in Sustainability Science, Deutsche Forschungs Gemeinschaft (German Research Foundation), German Federal Ministry for Economic Cooperation and Development, Natural Science Foundation of Guangdong Province and Australian Research Council Grants.

Source : msu.edu

Video: Turning Plant Defense Into a Management Strategy

Turning Plant Defense Into a Management Strategy

Understanding how a plant responds to stress is one thing.

Using that knowledge to make better management decisions is another.

Systemic acquired resistance, or SAR, is the plant's more direct defense response. When stress or infection occurs, the plant begins signaling throughout its system and preparing defensive compounds.

But if we know that response exists, can we help prepare the plant before the stress arrives?

The answer starts with understanding what triggers the response and what the plant needs to carry it out.

The Trigger and the Fuel

Salicylic acid plays an important role in triggering the SAR pathway.

Think of it as turning the truck on.

The engine may be running, but it still needs fuel to do the work.

In this case, manganese plays an important role in supporting the enzyme systems involved in the plant's defensive response.

This makes manganese status an important part of the conversation. Whether a producer is using tissue testing, sap analysis, or simply scouting for visible deficiency symptoms, the goal is to make sure the plant has adequate manganese available.

Manganese is required in relatively small amounts, but that does not make its role small.

If the plant receives a signal to defend itself but lacks the nutrition needed to support that response, it may struggle to carry out the process efficiently.

The trigger matters.

The fuel matters too.

Prepare Before the Stress Arrives

The best time to think about stress management is before the plant is overwhelmed.

Once a crop is already struggling, management can quickly turn into a game of catch-up.

This is similar to nitrogen management. Once a plant becomes severely deficient, correcting the problem does not necessarily erase the time and yield potential already lost.

Plant defense can work the same way.

Low-rate, targeted approaches designed to support the SAR pathway may fit best ahead of an expected stress event rather than after significant damage has already occurred.

That requires producers to think about predictable stress.

We may not know exactly what the weather will do tomorrow, but we generally know summer heat is coming. We know certain field conditions increase disease pressure. We know a herbicide application can temporarily stress a crop as the plant processes the chemistry.

Even a properly timed and labeled herbicide application can create a temporary response in the plant.

That does not mean the herbicide is bad.

Weeds can create significantly more yield loss than the temporary stress caused by controlling them.

The question is not whether we should eliminate every stressor.

The question is whether we can better prepare the plant to manage necessary and predictable stress.

Not All Stress Is Bad

Stress is a normal part of plant growth.

A perfectly stress-free environment does not exist in the field.

In fact, some stress is necessary for normal plant development. A plant responds to wind, temperature, moisture, sunlight, and countless other environmental signals throughout the season.

The environment is stress.

The plant's job is to manage it.

Problems begin when the stress load becomes greater than the plant's ability to respond.

Extreme heat, drought, high salt concentrations, disease pressure, and even certain management practices can add to that load.

This is where understanding SAR becomes useful.

Instead of waiting until the plant is visibly struggling, producers can begin identifying periods when stress is likely and make management decisions around those windows.

ISR Starts With the Soil

While SAR is a more direct defense response, induced systemic resistance, or ISR, brings the conversation back to soil health.

The longevity of a farm is closely connected to the health of its soil.

Carbon plays a major role because it supports biological life within the soil. Bacteria, fungi, and other organisms interact with plant roots and influence how the plant grows, accesses nutrients, and prepares for stress.

This is why soil health cannot be reduced to one product or one application.

It is a system.

Keeping living plants in the field longer can support biological activity. Cover crops may fit some operations. Better water management can improve soil conditions.