粒径、包膜厚度及淋溶模式对控释肥氮素释放特性的影响

Effect of granular diameter、coating thickness and leaching patterns on characteristics of nitrogen releasing of controlled release fertilizer

【目的】为正确评价包膜控释肥养分释放机理及降低控释肥制造成本提供理论依据。【方法】采用培养土柱淋溶试验，探讨粒径（D1=2．5～3mm、D2=4～5mm）、包膜厚度（CTh1=50g／m^2、CTh2—70g／m^2）以及淋溶模式（干湿交替淋溶、常规间歇淋溶）对控释肥氮素释放特性的影响。【结果】在常规间歇淋溶模式下，粒径大小对控释肥氮素累积释放率无明显影响。而同一粒径下，包膜厚度对控释肥氮素累积释放率有影响，培养5～54d，包膜厚度小（50g／m^2）的控释肥氮素累积释放率基本上明显大于包膜厚度大（70g／m^2）的控释肥，前者平均是后者的1．25倍。淋溶模式影响控释肥氮素累积释放率，常规间歇淋溶模式下控释肥氮素累积释放率大于干湿淋溶交替模式，前者平均是后者的1．26倍。【结论】当粒径对控释肥氮素释放特性无明显影响时，可采用大粒径核芯代替小粒径核芯制造相同厚度的控释肥，既可以达到相似的肥效，又降低了控释肥的生产成本。

[Objective] The study was done to provide a theoretical basis for correct assessment of controlled release fertilizer （CRF） which released mechanism and to reduce the cost of CRFs. [Method] This paper studied the effects of granular diameter （D1 = 2. 5- 3 mm, D2 = 4-- 5 ram）, the coating thickness （CThl = 50 g/m2 , CTh2 = 70 g/m2 ） and leaching patterns （Dry-wetting alternation, Normal intermittent） on the nitrogen release rate of CRFs by soil column leaching experiment. [Result] Granular diameter had little effect on the nitrogen accumulative release rate under the normal intermittent leaching patterns. Coating thickness had influence on the nitrogen accumulative release rate and the release rate of CThl （ 50 g/m2） was significantly higher than that of CTh2（ 70 g/m2） during 5--54 d for the same diameter fertilizer. The release rate of the former was 1.25 folds higher than that of latter in average. Leaching patterns had influence on the nitrogen accumulative release rate. The release rate of the normal intermittent leaching under constant soil moisture was significantly higher than that of the dry-wetting alternation leaching system. The leaching rate of the former was 1.26 folds higher than that of the latter in average. [Conclusion] When granular diameter had no clear effect on CRFs, big granular diameter may replace small granular diameter to manufacture controlled release fertilizer of the same thickness. This can achieve similar fertilizer efficiency,and reduce production costs of CRFs.