Zeolite-enriched manure for agricultural fields
Natural zeolites have been used successfully since the 1960s for fertilizing agricultural crops. Utilizing zeolite’s cation exchange capability, they are first saturated with a concentrated ammonium ion solution and then incorporated into crop soils. Because surface-colonizing microbes can access nitrogen sequestered within zeolite, zeolites saturated with ammonia-N have proven to be an excellent long-term, slow-release fertilizer when applied to agricultural crops. The key difference here is that the ammonia zeolite sequesters comes only from the animal manures naturally – in other words, they have already been paid for though feed rather than having to pay more for synthetically manufactured ammonia.
In fact, incorporating zeolite into CAFO operations is a technologically simple approach for minimizing ammonia losses from CAFOs thereby improving animal health and occupational safety. Furthermore, unlike fresh manure, zeolite-enriched manure can be stored or composted with no loss of nitrogen. This allows farmers to apply the zeolite-enriched manure to agricultural fields at any time without creating environmental risks. Applying zeolite-enriched manures to agricultural fields has many advantages over applying ordinary (unprocessed) manure:
- The sequestering of ammonia by zeolite maintains a N:P ratio in the zeolite-enriched manure that is more balanced with respect to crop nutrient requirements. When applied to field crops, this more nutrient-balanced natural fertilizer reduces the risk of phosphorus saturation in soils and subsequent soluble phosphorus leaching into surface and groundwater.
- Because of ammonia sequestering, the zeolite-enriched manure can be applied at different times of year while still maintaining a high N content, but with minimal odors and a greatly reduced risk of nitrate leaching into surface and groundwater.
- Zeolites incorporated into soils can still take up and release ammonia produced from organic decomposition in the soils and from subsequent fertilizer additions –which promotes further on-farm recycling of nitrogen originally purchased as feed.
- The cation-exchange properties of zeolites also increase the capacity of fields to safely sequester trace heavy metals found in manures.
- The ability of zeolite to absorb water makes composted manure volumes smaller and easier to manage and transport; later it can release absorbed water into the soil during dry periods.
- Unlike ordinary fresh manure, the relatively dry compost does not coat crop leaves, which causes salt burns and reduces photosynthetic activity.
- The consistency of zeolite-enriched manure is more uniform, reducing the risk of over or inconsistent application.
- Zeolite-enriched manure increases soil filtration rates, which in turn increases nutrient availability to crops, stabilizes soil moisture, and reduces surface erosion and associated losses of nitrogen and phosphorus.
- Since zeolites do not break down under ambient conditions, field crops will continue to benefit long after the composted manure is applied and totally decomposed. Zeolite accumulation in agricultural soils will benefit both water retention/management and crop yield consistency and sustainability.