Smarter fertilizers can reduce environmental contamination while maintaining both volume and quality improvement

Farmers typically fertilize crops in two ways. They spray fields with ammonia, urea or other substances that generate the nutrient nitrogen when they react with water. And they apply granules of potash or other minerals to produce phosphorus, also in reaction to water. But relatively little of those nutrients makes its way into the plants. Instead, much of the nitrogen goes into the atmosphere in greenhouse gases, and phosphorus ends up in watersheds frequently triggering excessive growth of algae and other organisms. Controlled-release formulations, in contrast, can ensure that significantly higher levels of nutrients reach the crops, leading to higher yields with less fertilizer.

A class known as slow-release fertilizers has been sold for some time. These formulations typically consist of tiny capsules filled with substances that contain nitrogen, phosphorus and other desired nutrients. The outer shell slows both the rate at which water can access the inner contents to liberate the nutrients and the rate at which the end products escape from the capsule. As a result, nutrients are meted out gradually, instead of in a wasteful, rapid burst that cannot be absorbed efficiently. Newer formulations include substances that slow nutrient delivery still further by retarding the conversion of starting materials, such as urea, to nutrients.

Fertilizers that more fully fit the description “controlled release” have been developed recently – made possible by sophisticated materials and manufacturing techniques that can tune the shells so they alter nutrient-release rates in desired ways as the soil’s temperature, acidity or moisture changes. By combining different types of tuned capsules, manufacturers can make fertilizers that have profiles tailored to the needs of specific crops or growing conditions. Companies such as Haifa Group and ICL Specialty Fertilizers are among those offering more precise control. Haifa, for instance, ties the rate of nutrient release solely to temperature; as temperatures rise, the rates of crop growth and of nutrient emission increase together.

Although controlled-release technologies make fertilizers more efficient, they do not eliminate all drawbacks of fertilizer use. The products still include ammonia, urea and potash, for example; producing these substances is energy-intensive, which means that their manufacture can contribute to greenhouse gas production and climate change. This effect could be mitigated, however, by using environmentally friendlier sources of nitrogen and incorporating microorganisms that improve the efficiency of nitrogen and phosphorus uptake by plants. There is no evidence that the materials composing the shells hurt the environment, but this risk must be monitored whenever any new substances are introduced in high volumes.

Controlled-release fertilizers are part of a sustainable approach to agriculture known as precision farming. This approach improves crop yield and minimizes excessive nutrient release by combining data analytics, AI and various sensor systems to determine exactly how much fertilizer and water plants need at any given time and by deploying autonomous vehicles to deliver nutrients in prescribed amounts and locations. Installing precision systems is costly, though, so only large-scale operations tend to have them. In comparison, advanced controlled-release fertilizers are relatively inexpensive and could be a front-line technology that would help farmers to sustainably increase crop production.

In Vietnam's Mekong Delta, including 12 southern provinces and Can Tho city, farmers are increasingly switching to smart rice farming to improve yields, cut costs and protect the environment, local media reported.

They use fewer seeds, pesticides and fertilizers compared to traditional farming methods without losing out on yield or quality, while utilizing advanced technologies like smart rice seeding and transplanting machines and other smart devices. In Dong Thap and Tra Vinh provinces, farmers have used smart rice farming to good effect. Their use of urea has declined by around 40 percent and the cost of labor for fertilizing their fields has fallen by 75 percent.

Fertilizer deep placement has helped reduce greenhouse gases by 40 percent when used with alternate wetting and drying irrigation. Smart farming reduces the amount of water required for irrigation by 30 percent and the labor cost and seed requirement by 50 percent. It also reduces saltwater intrusion into rice fields as farmers can actively regulate freshwater through smart devices that monitor the quality of water. The profit from this model is 20 percent higher than from traditional methods, according to farmers.

In the future, by making a step further to use controlled-release fertilizers, farmers in countries like Vietnam could continue to keep their production grow both in terms of volume and quality while constantly reduce greenhouse gas emissions and climate impact.

Source: World Economic Forum, VNS