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以青海省3类典型高寒草甸为研究对象,分析土壤可溶性有机氮库和土壤氨基酸库种类、质量分数及其季节动态变化过程,确定牧草不同发育期土壤的供氮能力,为进一步研究高寒草甸植物吸收土壤氮素奠定基础.结果表明:高寒草甸土壤中最占优势个体游离氨基酸是苯丙氨酸和天冬氨酸,其次是亮氨酸、精氨酸、脯氨酸、组氨酸、谷氨酸、赖氨酸和甘氨酸,它们占总游离氨基酸的80%~90%;藏嵩草草甸生长季土壤总游离氨基酸态氮平均质量分数为6.90×10~(-6),最高值出现在6月低.矮嵩草草甸生长季土壤总游离氨基酸态氮平均质量分数为7.44×10~(-6),随生长季土壤总游离氨基酸逐渐上升,到5月底达到最大值,随后逐渐下降.退化矮嵩草草甸土壤总氨基酸态氮季节变化不显著,平均质量分数为5.04×10~(-6);藏嵩草草甸土壤可溶性有机氮质量分数分别在4、9月初有2个高峰,分别为1.711×10~(-5)、2.594×10~(-5),6月底达到最低值,仅为7.63×10~(-6);矮嵩草草甸土壤可溶性有机氮质量分数高峰分别在4月底和10月初,分别为2.36×10~(-5)、2.036×10~(-5),6月底达到最低(1.1×10~(-5));退化矮嵩草草甸土壤可溶性有机氮质量分数季节动态与矮嵩草草甸相似,最高值出现在4月底,为1.582×10~(-5),最低值出现在6月(5.57×10~(-6));矮嵩草草甸土壤可溶性有机氮质量分数占土壤可溶性总氮的50.01%,土壤铵态氮占可溶性总氮的49.99%.土壤可溶性氨基酸态氮占土壤可溶性总氮的2 1.80%、占土壤可溶性有机氮的43.60%.与土壤无机氮比较,土壤可溶性有机氮库和可溶性氨基酸态氮库在高寒草甸土壤氮素中占有重要份额,这也是高寒植物可利用氮素的重要组成成分.
Taking three types of alpine meadow in Qinghai Province as the research object, the types and mass fractions of soil soluble organic nitrogen and soil amino acid were analyzed to determine the nitrogen supplying ability of soil at different growth stages. In order to further study the effects of alpine grass The results showed that the free amino acids of the most dominant individuals in the alpine meadow soil were phenylalanine and aspartic acid, followed by leucine, arginine, proline and histamine The contents of total free amino acid nitrogen in the growing season of Kobgyri grassland were 6.90 × 10 -6, The highest value appeared in June low.The total content of free amino acid nitrogen in the soil of Kobresia humilis meadow in the growing season was 7.44 × 10 ~ (-6), with the total free amino acid in the soil increasing gradually and reached the maximum at the end of May , Followed by a gradual decline.The total amino acid nitrogen in the degraded Kobresia humilis meadow was not significantly affected by seasonal changes, with an average mass fraction of 5.04 × 10 -6 (P <0.05). The contents of soil soluble organic nitrogen There are 2 peaks early this month, respectively, 1.711 × 10 ~ (- 5), 2. 594 × 10 ~ (-5), reaching the lowest at the end of June, only 7.63 × 10 ~ (-6). The peak of soil dissolved organic nitrogen in Kobresia humilis meadow was at the end of April and And the lowest was (1.1 × 10 -5) at the end of June. The content of soil dissolved organic nitrogen in the degraded Kobresia humilis meadow was significantly lower than that in the early October (2.36 × 10 ~ (-5), 2.036 × 10 ~ (-5) The seasonal dynamics was similar to that in Kobresia humilis meadow, and the highest value appeared at the end of April, which was 1.582 × 10 ~ (-5) and the lowest value appeared in June (5.57 × 10 ~ (-6)). Kobresia meadow soil The content of soluble organic nitrogen accounted for 50.01% of the total soluble nitrogen in soil and 49.99% of the total soluble nitrogen in soil, and soluble amino acid nitrogen in soil accounted for 2.80% of total soluble nitrogen in soil and 43.60% of soluble organic nitrogen in soil. Compared with soil inorganic nitrogen, soil soluble organic nitrogen pool and soluble amino acid nitrogen pool occupy an important part of soil nitrogen in alpine meadow, which is also an important component of available nitrogen in alpine plants.