THE PREPARATION OF INORGANIC-ORGANIC ADJUVANT FERTILIZER AND THE TRANSFORMATION PROCESS OF NUTRIENT WITH ISOTOPIC TRACER TECHNIQUE

The application of struvite precipitation is not widespread for high cost. To reduce the cost, struvite can be used as slow-release fertilizer. However, struvite is not suit for using as basic fertilizer for low nitrogen content. Therefore, a new inorganic-organic adjuvant fertilizer was prepared, struvite was used as wrapper, and organic fertilizer as core. The results showed that the cumulative release rate, the primary dissolution rate and the differential dissolution of phosphorus and nitrogen have a similar upward trend with the increase of the weight rate of struvite. When the weight rate of struvite and the organic fertilizer was 3:1, the cumulative release rate of phosphorus and nitrogen were 37.444%, 15.224%, respectively. The release amount of phosphate, TP and nitrogen at the weight rate of struvite:organic fertilize 2:1 were 5 mg/L, 8mg/L and 3 mg/L, respectively. The results of isotope tracer technique showed that the value of dl5N/14N in vegetables root is reached to 160.8. It can be proved that nitrogen from struvite were ingested by vegetables, and most of which were ingested by vegetables roots.