桂林毛村岩溶区和非岩溶区牧草养分动态的对比研究

通过进行岩溶区和非岩溶区牧草田间对比试验,测定植被在生长季内( 6- 8月)的养分动态变化,并结合N / P化学计量学的原理和方法,研究了岩溶区牧草的养分限制状况。结果表明: ( 1)在生长季节的6- 8月,岩溶区4种牧草N、P养分浓度都具有显著的随月份的增长而减少的趋势。从岩溶区和非岩溶区所测定的4种牧草养分结果来看,岩溶区牧草的N素平均值为22. 79 mg /g ,非岩溶区牧草的N素略小于岩溶区,为22. 15 mg /g ;岩溶区的P素平均值为6. 03 mg /g ,非岩溶区牧草的P素小于岩溶区,为5. 35 mg /g。( 2)无论是岩溶区还是非岩溶区,牧草的N /P与N 的相关性最大,相当系数都大于0. 6,与非岩溶区不同的是,岩溶区牧草的N /P与Ca 的相关性也很大,而非岩溶区的则较小。( 3)岩溶区牧草植物体Ca、Mg总含量分别是非岩溶区的2和1. 5倍。不同种类的牧草对Ca、Mg 的吸收和累积能力有较大的差异,本研究中的类玉米其钙含量远远小于其它3种牧草的钙含量。 

Comparison on the regime of herbage nutrient between karst and non karst area in Maocun village, Guilin

Many field experiments have shown that nitrogen (N) and phosphorus (P) are the most limited nutrients. In order to determine the nutrient situation, this paper examined the nutrient regime of four kinds of herbage in their growth period under different geologic background soils.The limited nutrients in karst area were investigated under the principles and methods of N/P stoichiometry method. The results are as follows: (1) The N and P concentrations of the four kinds of herbage in karst area had a significant monthly regime from June to August.It is found that the average of N concentration is 22.79 mg/g in karst area, but 22.15 mg/g in non karst area; that the average of P concentration is 6.03 mg/g in karst area, they are lower in non karst area.(2)The relativity between N/P and N is the most prominent whether in karst or non karst area; the relativity between N/P and Ca is prominent in karst area but not in non karst area.(3)The total Ca and Mg concentrations in karst area are 2 and 1.5 times higher than those in non karst area, and there is obvious difference in the capability of absorbency and cumulation to calcium and magnesium among the four herbages. The calcium concentration of teosinte is much smaller than that of the other three herbages in our experiment.