重庆市化肥使用与残留的时空分异特征研究

Spatial and Temporal Variability of Fertilizer Application and Residue in Chongqing

通过采集39个样本,调查研究了重庆市1998～2002年化肥使用与残留的分布特征。重庆市化肥全年使用水平为317.08 km/hm^2,高于全国平均水平。都市发达圈水平最高达758.24 km/hm^2,是渝西走廊的2倍。按施肥量水平则分为高施肥量区、中施肥量区、低施肥量区。施肥量水平与粮食产出、种植业经济产出呈明显的负相关性,施肥量越高,其投入效率越低,呈现出明显的报酬递减规律。化肥当季使用水平(x)与粮食产量(y)之间的关系为一抛物线方程。化肥平均利用率为35.72％,其中高施肥量区域最低,只有32.33％,低施肥量区域则达到49.12％。化肥使用总体上基本平衡,但过量使用、基本平衡和可增加使用的区县分别有9,13,17个。都市发达圈为化肥过量使用,渝西走廊与三峡库区为基本平衡。化肥残留总量最高的是三峡库区,每年进入三峡库区重庆段的氮肥约为10.31×10~3t/a,磷肥13.60×10~3t/a,严重影响了三峡水库水质。直辖后化肥当季使用水平和全年使用水平分别减少18.83％,43.28％,单位化肥的粮食产出减少28.35％,化肥利用率减少31.78％,但单位化肥的种植业经济产出增加80.93％。

39 samples were collected to investigate the distribution of fertilizer application and its residue in Chongqing from 1998 to 2002. The amount of fertilizer applied annually in Chongqing, 317. 08 kg/hm^2, was more than the average of whole China. In details, the amount of fertilizer appliedin metropolitan region of Chongqing, 758. 24 kg/hm^2, was the greatest and twice of that in western Chongqing. According to the amount of applied fertilizer, fertilizer application area in Chongqing can be classified into 3 regions, that is, the maximum fertilizer input region, the middle fertilizer input region and the low fertilizer input region. There was a significant negative correlation between the amount of fertilizer applied at current season (x) and the grain yield (Y), which could be described by the following equation: y=2677. 03+22. 044x-0. 045x^2. The average fertilizer utilization efficiency (FUE) was 35. 72%. FUE in the maximum fertilizer input region, which was the lowest, and that in the low fertilizer input region was 32. 33 % and 49. 12%, respectively. In all, the fertilizer applied could basically keep balance, however, there were 9 excessive-fertilized counties. The residue of fertilizer was the highest in Three Goges Reservoir where 10. 31× 10~3 t nitrogen fertilizer and 13. 60× 10~3 t phosphorus fertilizer were applied yearly. After Chongqing was in direct jurisdiction, the application of fertilizer at current season and that in whole year decreased 18. 83% and 43. 28%, respectively. As far as unit fertilizer was concerned, the grain output de- creased 28. 35 % and FUE decreased 31. 78%, the economic output of cropping, however, increased 80. 93%.