畜禽粪污土地承载力系统动力学模型及情景仿真

为实现畜禽粪污土地承载力系统评估、预判其发展态势及考察不同减排政策的实施效果,本文进行畜禽粪污土地承载力系统模型的设计、仿真与情景调控。在社会经济、畜禽养殖和种植业各子系统及其要素分析的基础上,以中国北方畜牧大市——石家庄市为例,建立畜禽粪污土地承载力系统动力学模型并进行有效性检验。系统运行结果显示,模型具有具有较好的稳定性,而且模拟值与实际值误差普遍小于10%,因此模型有效。在确定模型有效之后,应用系统动力学模拟仿真不同方案下的石家庄市2007—2025年畜禽养殖土地承载力变化情况。本文设置了4种与系统惯性发展相比较的方案——调整养殖业经济结构、调整环境保护治理投资、调整粪肥占施和协同发展模式,并针对上述5种情景进行仿真。仿真结果显示:1)惯性趋势发展条件下,畜禽养殖业和种植业的产出规模都有增长,但种植业产量增长不及畜禽养殖业的增长,致使种植业难以消纳畜禽养殖产生的氮磷排放,土地承载压力加大;2)调整养殖业经济结构情景下,氮、磷平衡承载均呈现出下降的趋势,但磷平衡承载仍存在压力;3)调整环境保护治理投资情景下,氮平衡承载处于可载状态,磷平衡承载压力下降明显,但只有后8个年度可载;4)调整粪肥占施情景下,氮平衡承载处于可载状态,磷平衡承载情况虽好于初始情景,但仍超载;5)协同发展模式下,氮、磷平衡承载压力均呈下降趋势,且氮、磷承载均处于可载的水平,通过比较分析发现,协同发展模式的效果最好。本研究一方面为开展畜禽养殖污染监测评估工作、建立畜禽养殖污染评估机制提供支撑,另一方面为畜牧大市(县)和其他资源环境超载区养殖业发展的调控提供科学依据。

System dynamic model and scenario simulation of land carrying capacity for livestock and poultry manure

Abstract: To implement systematic evaluation of land carrying capacity for livestock and poultry manure, prejudge its development trend and inspect the implementation effects of different emission reduction policies, this paper conducts the design and simulates different scenarios of land carrying capacity system model for livestock and poultry manure. Based on analyzing various subsystems of social economy, livestock and poultry breeding, crop planting and land carrying, and their elements, we established a system dynamic model of land carrying capacity for livestock and poultry manure, taking Shijiazhuang City as an example, which was an important city of animal husbandry in north of China. The system operation results indicated that: The model had good stability and reality, the error between the simulated value and the measured value was generally less than 10%. Therefore the model was effective. The system dynamic model was used to simulate the carrying capacity of livestock and poultry farming land in Shijiazhuang City from 2007 to 2025 under different scenarios. Five scenarios were designed. Scenario1: Inertial trend development condition, adjusting the economic structure of the animal husbandry, the investment in environmental protection, the proportion of manure and fertilizer and the mode of coordinated development, the simulation results show that: the output scale of animal husbandry and planting has increased, but the output growth of planting is inferior to that of livestock and animal husbandry, making it difficult for planting to consume nitrogen and phosphorus emissions by animal husbandry, and bringing more land carrying pressure. Scenario 2: Adjusting the economic structure of animal husbandry, both nitrogen and phosphorus balance carrying capacity present a downward trend, but phosphorus balance carrying pressure still exists. Scenario 3: Adjusting the environmental protection governance investment, nitrogen balance carrying is in the loadable state. Although the phosphorus balance carrying pressure is obviously decreased, only 8 years are loadable. Scenario 4: Adjusting the manure use ratio, nitrogen balance carrying is in the loadable state. The phosphorus balance carrying with improvement over the initial situation is still overloaded. Under the coordinated development mode, both nitrogen and phosphorus balance carrying pressure present a downward trend, both nitrogen and phosphorus balance carrying capacity are at the loadable level. It can be found through comparative analysis that the coordinated development mode has the best effect. This study provides support for carrying out monitoring and evaluation of livestock and poultry pollution and establishes an assessment mechanism for livestock and poultry breeding pollution on one hand. On the other hand, this paper provides scientific basis for the regulation and control of animal husbandry development in major livestock cities and other resources and environment overloading areas.