不同种养结合区农田系统氮磷平衡分析

Nitrogen and Phosphorus Balance of Cropland at Regional Scale for Integrated Crop-Livestock Farming System in Two Different Areas

山东禹城和湖南桃源是位于我国不同地区均以种养生产为主的两个县(市),根据养分平衡原理对这两个县级区域尺度的农田系统氮、磷收支状况进行了计算分析,结果表明:自1980年以来,单位面积耕地上氮磷的输入量与输出量均表现为不断增加,但是,因为输入增长高于输出增长,导致农田系统产生较多氮磷养分盈余,两个地区存在明显差异。禹城农田系统氮磷盈余量呈逐年增长趋势,氮盈余量从133.8 kgN.hm-2增加到目前的450 kgN.hm-2以上,磷盈余量从6.2 kgP2O5.hm-2增加到目前的148.9 kgP2O5.hm-2;在其11个乡镇中有10个表现为氮盈余、9个表现为磷盈余,其中氮盈余量最多的高达841.8 kgN.hm-2,磷盈余量最多的达到297.8 kgP2O5.hm-2。桃源农田系统氮磷盈余量表现为先增后降,氮盈余量从100 kgN.hm-2左右增加到2002年达到峰值253.7 kgN.hm-2后,逐渐下降到目前的150.0 kgN.hm-2左右,磷盈余量从20.0 kgP2O5.hm-2左右增加到2002年的峰值95.9 kgP2O5.hm-2后,下降到目前的34.4 kgP2O5.hm-2;在其40个乡镇中有36个表现为氮盈余、26个表现为磷盈余,其中氮盈余量最高的达到561.7 kgN.hm-2,磷盈余量最高的为171.1 kgP2O5.hm-2。农田系统氮磷养分大量盈余主要是源于投入化肥量和承载粪便量较高,山东禹城明显高于湖南桃源,所以,为了减少养分盈余损失,应根据农田作物生长养分需求尽可能地减少化肥投入,并根据耕地粪便承载容量在区域内外合理调配畜禽粪便的施用。

The nitrogen（N） and phosphorus（P） balances of cropland within two different areas of crop-animal mixed farming system,Yucheng County,Shandong Province and Taoyuan County,Hunan Province were taken as the case study.The result shows that N and P input to the cropland has been increased since 1980,so is the case of N and P export.However,a large amount of N and P surplus was produced owing to the increasing input of N and P to cropland which is greater than the export,and there were differences between the two areas.In the cropland of Yucheng County,the surplus of N and P has been increasing year by year,annual N surplus per hectare of farmland was greatly increased from 133.8 kgN·hm-2 to over 450.0 kgN·hm-2,and annual P surplus per hectare farmland was increased from 6.2 kgP2O5·hm-2 to 148.9 kgP2O5·hm-2.As a result,in 11 villages and towns of Yucheng,10 of them show N surplus and 9 of them have P surplus to different extent of which the largest amount of N surplus reaching 841.8 kgN·hm-2 and the P surplus 297.8 kgP2O5·hm-2.In the cropland of Taoyuan County,the surplus amount of both N and P were increased till 2002,and then began to decline.The N surplus increased from about 100.0 kgN·hm-2 to the ceiling amount of 253.7 kgN·hm-2,then decreased to the present about 150.0 kgN·hm-2,and the P surplus increased from about 20 kgP2O5·hm-2 to the peak of 95.9 kgP2O5·hm-2 and then decreased to about 34.4 kgP2O5·hm-2 at present.In 40 village and towns of Taoyuan County,36 of them exhibit N surplus and 26 of them appear P surplus to different extent,of which the highest amount of N surplus is 561.7 kgN·hm-2and the highest amount of P surplus is 171.1 kgP2O5·hm-2.A great deal of N and P surplus resulted from either overuse of fertilizer or overload of manure within cropland,and the surplus amount of both N and P in Yucheng County is greater than that in Taoyuan County.To cut down N and P surplus and loss,fertilizer should be minimized as much as possible according to crops need,besides manure should be applied inside and outside the area according to the carrying capacity of cropland to manure.