陇东典型草原土壤和植被对滩羊轮牧和氮素添加的响应

发布时间：2018-05-20 00:29

本文选题：典型草原 + 滩羊　；参考：《兰州大学》2015年硕士论文

【摘要】：放牧是全球最重要的家畜生产方式之一,氮是维持放牧生态系统最重要的营养元素之一。为此,以陇东黄土高原滩羊轮牧系统为对象,研究放牧率(围封,2.7 sheep/ha,5.3 sheep/ha,8.7 sheep/ha)和N添加水平(0 g/m2、5g/m2、10g/m2、 20 g/m2)对草地土壤N矿化作用、温室气体排放和植被特征的影响。主要结果如下：(1)2013年土壤NH4+-N和矿质N含量在8月份达到最大值,分别为15.97mg/kg和36.95 mg/kg, NO3--N含量在9月份达到最大值23.86 mg/kg；2014年NO3--N、NH4+-N和矿质氮含量都在7月份达到最大值,分别为57.37 mg/kg、11.19mg/kg和68.56 mg/kg。土壤NO3--N、NH4+-N和矿质氮含量均与N素添加量线性相关显著。施N后,土壤N矿化速率分别在2013年8月和2014年7月达到年度最大值(p0.05),都显著高于未施N组(p0.05)；最低矿化速率分别出现在2013年9月和2014年8月(p0.05),均显著低于同期未施N组(p0.05)。说明施N短期内显著促进土壤N矿化作用,但随时间推移而作用减弱。放牧率对土壤N矿化无显著影响。施N量与放牧率对土壤N矿化的交互作用不显著,说明放牧会减弱施N对土壤N矿化的促进作用。(2)放牧率对草地C02排放的影响显著(p0.05),对CH4排放和N20排放的影响不显著；不同放牧率下,草地的CH4和N2O排放日动态存在差异,而C02排放日动态趋势大体一致。在5.3 sheep/ha放牧地中,草地CH4吸收速率和C02排放速率最大,分别为0.59×10-3mg·m-2·min-1和0.61 mg·m-2·min-1,但N20排放速率居中,为8.1×10-3mg·m-2·min-1; 8.7sheep/ha放牧地N2O排放速率最高,达到11.53μg·m-2·min-1。N素添加促进N20的排放(p0.05),抑制草地CH4吸收和C02排放。施N量对CH4、CO2和N20排放日动态变化趋势无显著影响。放牧率与施N量对CH4、CO2和N20排放速率的交互作用不显著。(3)施N量对茵陈蒿、长芒草和胡枝子生物量的影响无显著规律(部分施N量之间差异显著)。放牧率对植被生物量有显著影响,茵陈蒿、长芒草和胡枝子的生物量和总生物量都在5.3 sheep/ha放牧地中最高(p0.05),分别达到49.55g/m2、12.68 g/m2、13.67 g/m2、82.84 g/m2。放牧降低牧草粗蛋白含量,8.7 sheep/ha放牧地牧草粗蛋白含量最低,为45.16 g/kg,显著低于2.7 sheep/ha放牧地和5.3sheep/ha (p0.05);随着放牧率的增加,牧草磷含量相应增加。施N量对草地植被物种数无显著影响,但显著增加牧草粗蛋白含量。牧草粗蛋白含量与施N量线性正相关显著,y=0.665x+44.936(R2=0.9026,p0.01),在20 g/m2施氮组中牧草粗蛋白含量最高,达到57.37g/kg。N素添加对牧草磷含量没有显著影响。施N量和放牧率的交互作用对草地植被生物量、牧草粗蛋白含量和磷含量均不存在显著影响,说明放牧抵消N添加的作用。上述结果表明,放牧可能削弱N素添加对草原的作用,N素添加也可能减弱放牧对草原的作用,两者叠加可能有助于放牧生态系统的稳定。家畜排泄物、特别是尿的作用部分类似N添加,因此本研究表明适度放牧下,家畜的采食、践踏和排泄物的综合作用对于放牧系统的可持续利用有积极影响。
[Abstract]:Grazing is one of the most important livestock production methods in the world. Nitrogen is one of the most important nutrient elements for maintaining the grazing ecosystem. Therefore, the grazing rate (enclosure, 2.7 sheep/ha, 5.3 sheep/ha, 8.7 sheep/ha) and N addition level (0 g/m2,5g/m2,10g/m2, 20 g/m2) for N mineralization in the grassland soil in the Loess Plateau of the Loess Plateau of East Gansu Province are studied. The effects of greenhouse gas emission and vegetation characteristics are as follows: (1) in 2013, the soil NH4+-N and mineral N content reached the maximum in August, respectively 15.97mg/kg and 36.95 mg/kg, NO3--N content reached the maximum value of 23.86 mg/kg in September, and 2014 NO3--N, NH4+-N and mineral nitrogen reached the maximum value in July, respectively, 57 The contents of NO3--N, NH4+-N and mineral nitrogen in.37 mg/kg, 11.19mg/kg and 68.56 mg/kg. soil are all linearly correlated with the content of N element. After the application of N, the soil N mineralization rate reaches the annual maximum value in August 2013 and July 2014 respectively (P0.05), which are significantly higher than those in the unapplied N group (P0.05), and the lowest mineralization rate appears in September 2013 and August 2014, respectively. It was significantly lower than the non N group (P0.05) in the same period. It indicated that N significantly promoted soil N mineralization in the short term, but decreased with time. The grazing rate had no significant effect on soil N mineralization. The interaction of N amount and grazing rate on soil N mineralization was not significant, indicating that grazing would weaken the effect of N on the N mineralization of soil. (2) grazing rate pairs The effect of C02 emission on grassland was significant (P0.05), and the effects on CH4 emission and N20 emission were not significant. The dynamic trends of CH4 and N2O emission days were different at different grazing rates, while the dynamic trends of C02 emission days were the same. In the 5.3 sheep/ha grazing land, the maximum rate of CH4 absorption and C02 emission was 0.59 * 10-3mg, m-2. .61 mg / m-2. Min-1, but the rate of N20 emission is 8.1 * 10-3mg. M-2. Min-1, and N2O emission rate of 8.7sheep/ha grazing land is the highest, reaching 11.53 mu g. The interaction of CH4, CO2 and N20 emission rates was not significant. (3) the effects of N on the biomass of Artemisia Artemisia, manmania and Lespedeza were not significant (significant difference between partial application of N). The grazing rate had significant influence on the biomass of vegetation, and the biomass and total biomass of Artemisia Artemisia, manmanna and Lespedeza were the highest in the 5.3 sheep/ha grazing land. P0.05), the crude protein content of herbage was reduced to 49.55g/m2,12.68 g/m2,13.67 g/m2,82.84 g/m2. respectively. The crude protein content of herbage was lowest in 8.7 sheep/ha grazing land, which was 45.16 g/kg, significantly lower than 2.7 sheep/ha grazing land and 5.3sheep/ha (P0.05). With the increase of grazing rate, the content of pasture phosphorus increased correspondingly. There was no significant effect, but the content of herbage crude protein was significantly increased. The content of coarse protein in herbage was positively correlated with the amount of N, y=0.665x+44.936 (R2=0.9026, P0.01), the content of coarse protein in the 20 g/m2 nitrogen application group was the highest. The addition of 57.37g/kg.N was not significantly affected by the addition of 57.37g/kg.N. The interaction of N and grazing rates on grassland plant There was no significant influence on the biomass, the content of crude protein and the content of phosphorus, which indicated that grazing offset the effect of N addition. The above results showed that grazing may weaken the effect of N addition on grassland, and the addition of N may also weaken the effect of grazing on grassland. The superposition may contribute to the stability of grazing ecosystem. The role of urine is similar to the addition of N, so this study shows that the comprehensive effect of feeding, trampling and excretion of livestock has a positive effect on the sustainable utilization of grazing system under moderate grazing.
【学位授予单位】：兰州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S812

【参考文献】