N release characteristics of controlled/slowed-release fertilizer in different media and its effects evaluation

Several media (water, soil, sand, mixture of soil and sand, and mixture of soil and zeolite) were used to study the nutrient release characteristics of five controlledrelease fertilizers (CRFs) or slowrelease fertilizers (SRFs). The results showed that for a fertilizer there were significant differences in release pattern and release rate when dissolving or leaching in different media due to the different properties. So considerable errors might occur if water dissolution rate method was used to estimate the fertilizer efficiency although the method can make quick comparisons of nutrient release rates among different CRFs/SRFs. More objective and reasonable evaluation of CRFs/SRFs should be taken in the system of Fertilizersoilcrop. Comparatively, soil column leaching method was much closer to the field reality than water dissolution rate method.