INFLUENCE OF ENVIRONMENTAL CONDITIONS ON RELEASE RULES OF FERTILIZER FROM WOOD RESIDUE SLOW-RELEASE FERTILIZER SHELL

Slow/controlled-release fertilizer is a kind of fertilizer that controls or slows down the nutrient release rate according to a specific release rate or release period. The development and application of slow/controlled-release fertilizer is highly valued all over the world because of its benefits. However, the materials used for the fertilizer coating are mostly difficult to degrade, causing many negative effects to the environment. Wood is a porous material that could be used as a coating material through which fertilizers could infiltrate. In addition, a shell glued with adhesives could degrade in soil because of the loose structure, providing another channel for infiltration of fertilizer. As a kind of environmental friendly material, a wood residue fertilizer shell could be used to provide fertilizer for trees, flowers, and other plants. Toona sinensis wood residues were used as the raw material to manufacture a slow-release fertilizer shell using the secondary molding method. The influence of external environmental conditions such as temperature and rainfall on the release rules of fertilizers from shells were studied through artificial rainfall simulation. Results showed that release rules were similar in three sets of rainfall. The release amount increased quickly at the early stages and then decreased gradually. Also, the release amount changed as rainfall increased. Temperature also had a major influence on release rate of fertilizer from the shell. Generally, the release rate of fertilizer in the shell increased with increase of environmental temperature. The release amount kept relatively stable at lower temperatures. This study indicated that the wood residue shell could slow down the release of fertilizer. Both rainfall and temperature had a great influence on the release rate of fertilizer from the shell.