宁夏回族自治区农田—畜牧系统氮素流动与平衡时空变化特征

TEMPORAL AND SPATIAL VARIATIONS OF NITROGEN FLOW AND BALANCE IN CROP-LIVESTOCK PRODUCTION SYSTEM IN NINGXIA HUI AUTONOMOUS REGION

关键词:  NUFER模型  农牧系统  氮素平衡  宁夏  氮素利用率

Key words:  NUFER model  crop-livestock production system  nitrogen balance  Ningxia  N utilization rates

摘要:

目的 通过研究宁夏的农牧系统氮素流动及平衡特征，为农牧业绿色、协调发展提供理论基础。方法 文章以“农田—畜牧”系统为研究对象，利用2002—2021年的统计数据，运用 NUFER （Nutrient Flows in Food Chain，Environment and Resources Use）模型，开展对宁夏农牧系统氮素流动特征及利用效率的研究。结果 （1）2002—2021年宁夏畜牧系统氮素总量呈逐年上升趋势，从9.3万t增长到26.0万t；（2）宁夏农田系统氮素总量呈先上升后下降趋势，2013年均达到峰值，从94.8万t增长到2013年的126.0万t，2021年为118.3万t，其中化肥氮输入的占比最大，占氮素总量的80.9%~86.4%；（3）宁夏农牧系统氮素总量从99.6万t增长到126.7万t，趋势与农田系统一致。农牧系统氮素利用率为12.1%~19.7%，较我国其他地区偏低；环境排放量在2013年最高，为130.9万t；（4） 氨挥发为氮素环境排放量的主要损失形态，占氮素总投入的40%~50%。（5）从空间分布上看，2002年和2021年宁夏农牧系统氮素总量表现出极大的不平衡，在空间上氮素投入总量平罗县、青铜峡市、利通区和贺兰县区域明显大于其他地区，盐池县氮素总量最少，整体看农牧系统氮素投入呈现西北高、东南低的特征。结论 宁夏农牧系统化肥投入比例偏高，畜禽粪尿利用效率偏低，本地饲料供给不足，应减少化肥投入比例，增加氮素在农田和畜牧系统内的循环，减少外源氮素投入，合理分配氮素资源，提高农牧系统氮素利用率。

Abstract:

This paper aimed to provide a theoretical basis for the green and coordinated development of crop-livestock production system by studying the characteristics of nitrogen flow and balance in Ningxia 's crop-livestock production system. Taking the ' crop-livestock ' system as the research object, and using the statistical data from 2002 to 2021, the NUFER (Nutrient flows in food chain, environment and resources use) model was used to study the nitrogen flow characteristics and utilization efficiency of the crop-livestock production system in Ningxia. The results were showed as follows. (1) From 2002 to 2021, the total amount of nitrogen in the Ningxia livestock system increased from 93 thousand tons in 2002 to 260 thousand tons in 2021, showing an increasing trend year by year. (2) The total amount of nitrogen in the Ningxia cropland system increased from 0.948 million tons in 2002 to 1.183 million tons in 2021, showing a trend of rising first and then decreasing, which peaked at 1.260 million tons in 2013. Among them, the chemical fertilizer nitrogen input accounted for the largest proportion, accounting for 80.9 % ~ 86.4 % of the total nitrogen. (3) The total amount of nitrogen in the crop-livestock production system in Ningxia increased from 0.996 million tons in 2002 to 1.267 million tons in 2021, showing a trend of increasing first and then decreasing, and it reached a peak of 1.309 million tons in 2013. The nitrogen utilization rate of the crop-livestock production system was 12.1 % ~ 19.7 %, which was lower than those of other regions in China. Environmental emissions were the highest in 2013, reaching 1.309 million tons. (4) The ammonia volatilization was the main loss form of nitrogen environmental emissions, accounting for 40 % ~ 50 % of the total nitrogen output. (5) From the perspective of spatial distribution, the nitrogen input of Ningxia 's crop-livestock production system in 2002 and 2021 showed a great imbalance. The total nitrogen inputs in Pingluo county, Qingtongxia city, Litong district and Helan county were significantly larger than those in other regions, and the total nitrogen in Yanchi county was the least. The nitrogen input of crop-livestock production system in the northwest was higher than that in the southeast of Ningxia. In conclusion, the proportion of chemical fertilizer input in Ningxia crop-livestock production system is high, the utilization efficiency of livestock and poultry manure is low, and the local feed supply is insufficient. The proportion of chemical fertilizer input should be reduced, the circulation of nitrogen in crop-livestock production system should be increased, and the input of exogenous nitrogen should be reduced. The input of nitrogen resources should be allocated reasonably in order to improve the nitrogen utilization rate of crop-livestock production system.