【作者】 蒲小鹏；

【导师】 胡自治；

【作者基本信息】 甘肃农业大学 ， 草业科学， 2005， 博士

【摘要】 氮肥对农业生产贡献很大,是全世界应用最多的化学肥料,氮肥投入极大地改善了人类生存和生活条件;与此同时,氮肥的负面效应也在不断增加。本研究立足青藏高原这块生态脆弱区,以氮肥投入为出发点,研究分析了氮肥对当地草地畜牧业生产稳定性的影响。从2003～2005年,在青藏高原祁连山东段的甘肃农业大学金强河高山草原定位试验站进行了燕麦氮肥试验,在“土-草-畜”三位一体的草地生态系统思想指导下,分别研究氮素对燕麦群落、燕麦可消化养分、土壤常规养分和土壤酶活性的影响,定量化、模型化地反映了氮素在土-草子系统中的流转过程。结果表明:1、燕麦产量月动态:高寒牧区5月份月平均温度大于5℃,燕麦从5月中旬播种到9月下旬生长期结束,生育期约120天,产量的季节动态呈S曲线,可用Logostic曲线方程来模拟: ,其中x表示生长天数,值域[0,120],y为实际产量占最大产量的比例,值域[0,100]。2、氮肥与燕麦草产量关系:氮肥处理中的氮素以尿素计,草产量与施肥量变化趋势表现为二次曲线,其模型为: y = -0.0001x2 + 0.0253x + 9.5115 (R2 = 0.6626)其中,y-施肥后的小区产量,单位为t/h㎡.DM x-为施肥量,单位为kg/h㎡利用产量曲线可以对最佳施氮量进行预测,通过对模型求导、计算极值,得到的最大草产量和施肥量为11.1t/h㎡.DM和126.5㎏/h㎡。3、氮肥对燕麦各营养成分消化率的影响:用尼龙袋法测定燕麦干草消失率时,随施氮量增加DCP递增,施肥处理DNDF大于对照,DEE和DNFE却呈递减趋势。4、氮肥对燕麦总可消化养分的影响:TDN是根据植物概略养分以及各养分平均消化性来评价饲草,在概略养分基础上,结合了能量体系优点,成为综合的、比较直观的、最简单的一个饲料评价体系和草地生产能力评价的一种重要方法。试验中,TDN在F4处理取得最大值,596g/kg,F8下降为524 g/kg。这种变化趋更多还原

【Abstract】 Nitrogen fertilizer plays an important role for agricultural development, which was the most widely used chemical fertilizer over the world. Nitrogen fertilizer is closely related with the improvement of human’s living condition, however, it is recently found that excessive use of nitrogen fertilizer has brought much negative effects on soil and environment.The study on the relation between nitrogen fertilizer application and oat (Avena sativa L)production and environment stability in Qinghai-Tibetan Plateau was carried out on the Alpine Grassland Experimental Station of Gansu Agriculture University, which located in Tianzhu County, from 2003 to 2005. The components in garland ecosystem, including soil, grass and animal were involved in and the parameters including oat production, nutritive value of oat dry matter, soil nutrients and soil enzyme were measured. The results are shown as follows:1.Monthly dynamic of oat above-ground yield The dynamic change of oat yield in about 120 days growing period from May to September shown a S curve, which could be simulated by the following Logistic equation: y(%) = 100.8/(1+e6.628x-0.092)×100 x means days of growing; range from [0,120] y means proportion of real above-ground yield to the peak yield, range from [0,100]2. Relationship between nitrogen fertilizer and oat yield The relationship between above-ground yield and amount of nitrogen fertilizer could be expressed with the following quadratic regression equation: Y = -0.0001x2 + 0.0253x + 9.5115 (R2 = 0.6626) Y means yield, t/hm2. DM X means amount of nitrogen fertilizer, kg/hm2 The aboveground peak yield of oat and the proper applying amount of urea could be predicted by above-mentioned model as 11.1 t/hm2 and 126.5 kg/hm2 respectively.3.Effect of nitrogen fertilizer on nutritional composition and digestibility of oat Fertilization increased the content of CP (crude protein) in oat and it could be expressed by the following model: y= 0.1159x + 76.671, y was CP content of above-ground oat, %; X was amount of nitrogen fertilizer, kg/hm2.更多还原