我国典型农区耕地承载畜禽容量对比分析

根据农田养分平衡理论,对我国南北两个县级区域山东禹城和湖南桃源的耕地承载畜禽容量和负载指数进行了对比分析。 基于农田N收支情景分析表明:当农田施用粪便N分别占到总投入N的30%、60%和100%时,山东禹城耕地承载畜禽容量分别为4.1、8.3和13.8 LU·hm^-2,相应负载指数分别是2.2、1.1和0.7,湖南桃源耕地承载畜禽容量分别是4.4、8.7和14.6 LU·hm^-2,相应负载指数分别是1.4、0.7和0.4;基于农田N收支的耕地畜禽容量呈现为禹城略低于桃源,负载指数呈现为禹城显著高于桃源。基于农田P收支情景分析表明:当农田施用粪便P₂O₅分别占总施入P₂O₅的30%、60%和100%时,山东禹城耕地承载畜禽容量分别为6.7、13.5和22.5 LU·hm^-2,相应的耕地畜禽承载指数分别是1.3、0.7和0.4,湖南桃源耕地承载畜禽容量分别是2.5、5.1和8.5 LU·hm^-2,相应的负载指数分别是2.4、1.2和0.7,基于农田P收支的耕地畜禽容量呈现为禹城显著高于桃源,负载指数为禹城低于桃源。可见,禹城基于农田N收支的耕地承载畜禽容量显著低于基于农田P收支的耕地承载畜禽容量,桃源正好与禹城相反。因此,今后在制定减少农田环境污染对策时,禹城应首先考虑农田N收支及粪便N的有效管理与利用;桃源则应首先考虑农田P收支及粪便P的有效管理与利用,并且因为区域内乡镇之间存在较大差异,还应在乡镇之间进行协调平衡。

Carrying Capacity of Livestock in Cropland of Two Typical Regions Dominated by Agriculture in China

According to the nutrients demand and available loss of current cropping system, livestock density under environmental capacity in two different areas, i.e., Yucheng County in Shandong Province and Taoyuan County in Hunan Province, was analyzed on the basis of nutrition budget of cropland by different input scenarios of manure N and manure P₂O₅. When the input of manure N accounted for 30%, 60% and 100% of total input of N in cropland, the carrying capacities of livestock in the farmland of Yucheng are 4.1 LU·hm^-2, 8.3 LU·hm^-2, 13.8 LU·hm^-2 and the corresponding load indexes of the farmland are 2.2, 1.1, 0.7; and those in the farmland of Taoyuan are 4.4 LU·hm^-2, 8.7 LU·hm^-2, 14.6 LU·hm^-2 and 1.4, 0.7, 0.4 respectively. When the input of manure P₂O₅ accounted for 30%, 60% and 100%of total input of P₂O₅ in cropland, the carrying capacities of livestock in the farmland of Yucheng are 6.7 LU·hm^-2, 13.5 LU·hm^-2, 22.5 LU·hm^-2 and the corresponding load indexes of the farmland are 1.3, 0.7, 0.4. Those in the farmland of Taoyuan are 2.5 LU·hm^-2, 5.1 LU·hm^-2, 8.5 LU·hm^-2 and 2.4, 1.2, 0.7 respectively. The results show that the carrying capacity of livestock in farmland of Yucheng depending on nitrogen budget is smaller than depending on phosphorus budget and the load index by nitrogen budget is higher than by phosphorus budget, and that of Taoyuan are opposite with Yucheng. Furthermore, the obvious differences existed among townships within the two areas. Therefore, to prevent regional environment from livestock manure related pollution the livestock density and the quantity of manure should be restricted based on the assimilative capacity of cropland to nutrition. Nitrogen balance in Yucheng and phosphorus balance in Taoyuan should be paid special attention to separately; and the livestock and manure should be distributed evenly within each region.