摘要
采用GPS定位、深层土钻取样的方法,研究北京市254个深层土壤剖面硝态氮的空间分布特征与累积状况。0～400cm土壤剖面硝态氮累积总量保护地菜田最高,115个塑料大棚和日光温室平均达1230kg·ha-1;果园土壤仅次于保护地菜田,16个取样点平均为1148kg·ha-1;相比之下,露地菜田硝态氮累积量较低,15个点平均为697kg·ha-1;粮田最低,93个冬小麦-夏玉米轮作地块平均为459kg·ha-1,8个春玉米地块平均为420kg·ha-1,水稻田7个点平均仅为69kg·ha-1。同一利用类型、不同地块之间硝态氮累积量相差可达几倍到几十倍。硝态氮累积量超过800kg·ha-1的地块,保护地菜田有70.4%,果园50.0%,露地菜田33.3%,而冬小麦-夏玉米轮作地块和春玉米地块仅有8.6%和12.5%。从剖面分布来看,旱地农田土壤剖面硝态氮含量自上向下逐渐降低,水田土壤变化不大,通体较低;利用类型不同农田200～400cm土层硝态氮累积量所占比例在32%～40%,但绝对量相差极大。保护地菜田和果园分别高达434和424kg·ha-1,露地菜田为284kg·ha-1,冬小麦-夏玉米轮作地块与春玉米地块较低,分别为148和135kg·ha-1。综合来看,北京市保护地菜田和果园土壤剖面硝态氮过量累积问题突出,严重威胁地下水安全;粮田总体状况较好,但个别地区仍有一定污染潜力。
The potential of nitrate pollution of groundwater can be forecasted to a great extent by the soil nitrateaccumulation. By means of GPS and deep soil core sampling, nitrate content in 254 soil profiles under different land usetypes was studied in Beijing. NO3---N accumulation in 0-400 cm soil profiles in 115 protected vegetable fields was thehighest, averaged as 1 230kg·ha-1, and in 16 orchards and 15 open vegetable fields was 1148 and 697 kg·ha-1, in 93winter wheat and summer maize rotation fields and 8 spring corn fields was 459 and 420 kg·ha-1 respectively, the lowestwas paddy fields, only 69kg·ha-1 averaged by 7 fields. Even for the same land use types, NO3--N accumulation amongsampling fields exists great difference. The percent of soil profiles with NO3--N accumulation more than 800 kg·ha-1 was 70.4 in protected vegetable fields, 50.0 in orchards, 33.3 in open vegetable fields, while only 8.6 and 12.5 in winter wheat-summermaize rotation fields and spring corn fields. NO3--N content reduced sharply with the depth of soil profile in dryland fields.Although there was no remarkable difference in the ratio of NO3--N content in 200-400 cm soil layer to the whole profileamong various land use types, which was about 32 to 40 percent, NO3--N accumulation rates differs distinctly. The highestwas protected vegetable fields and orchards, which was 434 and 424kg·ha-1, respectively.The second was open vegetablefields which was 284kg·ha-1, while that in cereal fields was much lower, only 148 and 135 kg·ha-1 in winter wheat-summermaize rotation fields and spring corn fields, respectively. In the whole, over accumulation of soil NO3--N in protectedvegetable fields will give a serious menace to the quality of groundwater, while in cereal fields the menace is much lower.
出处
《中国农业科学》
CAS
CSCD
北大核心
2004年第5期692-698,共7页
Scientia Agricultura Sinica
基金
北京市自然科学基金资助项目(6982012)
