• Ammonia as a gas has the property of dissolving in soil water to form ammonium hydroxide. The challenge lies less in the application technique (= injection into the soil at low pressure) and more in the availability of ammonia. In the USA, anhydrous ammonia is used extensively in large-scale agriculture.
• Carbon Dioxide: In many horticultural (greenhouse) production systems, the rate of photosynthesis is limited by the transport of carbon dioxide into the leaves. This happens because the CO₂ concentration within the plant canopy drops due to plant uptake when the air exchange with the outside greenhouse air is too low (air exchange < 5 times per hour). Therefore, carbon dioxide can be applied to increase the ambient CO2 concentration around the plants, for example:

As CO2 gas from compressed (liquid) CO2, or dry ice,

By burning propane or butane,

By utilizing the exhaust gases from gas heating systems, etc.

This often leads to yield increases if a concentration of 400 ppm CO₂ is maintained near the leaves and gassing is applied from shortly after sunrise until about two hours before sunset.

Whether the investment pays off must be evaluated on a case-by-case basis. The Carborain method (= continuous burner under discussion) has not yet been successfully validated by independent institutions.