發(fā)布時間：2018-05-20 00:29

  本文選題：典型草原 + 灘羊��； 參考：《蘭州大學》2015年碩士論文

【摘要】：放牧是全球最重要的家畜生產(chǎn)方式之一,氮是維持放牧生態(tài)系統(tǒng)最重要的營養(yǎng)元素之一。為此,以隴東黃土高原灘羊輪牧系統(tǒng)為對象,研究放牧率(圍封,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)對草地土壤N礦化作用、溫室氣體排放和植被特征的影響。主要結(jié)果如下：(1)2013年土壤NH4+-N和礦質(zhì)N含量在8月份達到最大值,分別為15.97mg/kg和36.95 mg/kg, NO3--N含量在9月份達到最大值23.86 mg/kg；2014年NO3--N、NH4+-N和礦質(zhì)氮含量都在7月份達到最大值,分別為57.37 mg/kg、11.19mg/kg和68.56 mg/kg。土壤NO3--N、NH4+-N和礦質(zhì)氮含量均與N素添加量線性相關顯著。施N后,土壤N礦化速率分別在2013年8月和2014年7月達到年度最大值(p0.05),都顯著高于未施N組(p0.05)；最低礦化速率分別出現(xiàn)在2013年9月和2014年8月(p0.05),均顯著低于同期未施N組(p0.05)。說明施N短期內(nèi)顯著促進土壤N礦化作用,但隨時間推移而作用減弱。放牧率對土壤N礦化無顯著影響。施N量與放牧率對土壤N礦化的交互作用不顯著,說明放牧會減弱施N對土壤N礦化的促進作用。(2)放牧率對草地C02排放的影響顯著(p0.05),對CH4排放和N20排放的影響不顯著；不同放牧率下,草地的CH4和N2O排放日動態(tài)存在差異,而C02排放日動態(tài)趨勢大體一致。在5.3 sheep/ha放牧地中,草地CH4吸收速率和C02排放速率最大,分別為0.59×10-3mg·m-2·min-1和0.61 mg·m-2·min-1,但N20排放速率居中,為8.1×10-3mg·m-2·min-1; 8.7sheep/ha放牧地N2O排放速率最高,達到11.53μg·m-2·min-1。N素添加促進N20的排放(p0.05),抑制草地CH4吸收和C02排放。施N量對CH4、CO2和N20排放日動態(tài)變化趨勢無顯著影響。放牧率與施N量對CH4、CO2和N20排放速率的交互作用不顯著。(3)施N量對茵陳蒿、長芒草和胡枝子生物量的影響無顯著規(guī)律(部分施N量之間差異顯著)。放牧率對植被生物量有顯著影響,茵陳蒿、長芒草和胡枝子的生物量和總生物量都在5.3 sheep/ha放牧地中最高(p0.05),分別達到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,為45.16 g/kg,顯著低于2.7 sheep/ha放牧地和5.3sheep/ha (p0.05);隨著放牧率的增加,牧草磷含量相應增加。施N量對草地植被物種數(shù)無顯著影響,但顯著增加牧草粗蛋白含量。牧草粗蛋白含量與施N量線性正相關顯著,y=0.665x+44.936(R2=0.9026,p0.01),在20 g/m2施氮組中牧草粗蛋白含量最高,達到57.37g/kg。N素添加對牧草磷含量沒有顯著影響。施N量和放牧率的交互作用對草地植被生物量、牧草粗蛋白含量和磷含量均不存在顯著影響,說明放牧抵消N添加的作用。上述結(jié)果表明,放牧可能削弱N素添加對草原的作用,N素添加也可能減弱放牧對草原的作用,兩者疊加可能有助于放牧生態(tài)系統(tǒng)的穩(wěn)定。家畜排泄物、特別是尿的作用部分類似N添加,因此本研究表明適度放牧下,家畜的采食、踐踏和排泄物的綜合作用對于放牧系統(tǒng)的可持續(xù)利用有積極影響。
[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.
【學位授予單位】：蘭州大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：S812

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