Microbial nitrogen: Schizachyrium scoparium Nutrient Uptake Profiles

The objective of this experiment is to determine the distances over which Schizachyrium scoparium can reduce available soil N. This experiment is being conducted in field B, outside the fenced area of the microplots. Each experimental unit consists of a circular plot of 3 meters diameter, at the center of which there is a Schizachyrium scoparium plant. Two treatments are being tested:

1 (=A). All the vegetation around the central S. scoparium was killed with roundup at a rate of 2.04 g/m2 (1g of Isopropylamine salt of N (phosphonomethyl ) Glycine ). Spraying was repeated at the same rate as needed (Yearly folder). A plastic barrier, 80 cm high, was placed around each Schizachyrium scoparium plant to protect it from any drift that might occur. The area sprayed is the circle with 2 m radius around the central plant.

2 (=B). The vegetation around S. scoparium is left intact. Each treatment is replicated 5 times. The two treatments were randomly assigned to the 10 plots of the experiment.

The plot layout is:

Plot # Treatment
1 2
2 1
3 2
4 2
5 1
6 1
7 1
8 2
9 2
10 1

Soil samples were taken several times and the amount of ammonium and nitrate were determined at the lab. Soil samples were also taken once for mineralization rate, microbial biomass and total carbon determination. When plants reached maturity, they were harvested and dried for dry matter determination, then ground for tissue nitrogen determination. For an additional list of treatments see the treatment layouts in file trmte38.

本实验旨在测定须芒草（Schizachyrium scoparium）降低土壤有效氮的作用距离。实验于微区围栏外的B地块开展。每个实验单元为直径3米的圆形样地，样地中心种植一株须芒草。本实验设置两种处理方案：
1（=A）：以2.04 g/m²的剂量使用农达（Roundup）杀灭中心须芒草周围的所有植被，其中农达有效成分为每平方米1克N-(膦酰甲基)甘氨酸异丙胺盐；根据需要按相同剂量重复喷施（按年度归档记录）。为避免喷施漂移对中心植株造成影响，需在每株须芒草周围布设80厘米高的塑料隔离屏障，喷施区域为中心植株周边半径2米的圆形范围。
2（=B）：保留须芒草周围的原有植被。
每种处理均设置5次重复，两种处理随机分配至本实验的10个样地中，样地布局如下：
| 样地编号 | 处理编号 |
|---------|---------|
| 1 | 2 |
| 2 | 1 |
| 3 | 2 |
| 4 | 2 |
| 5 | 1 |
| 6 | 1 |
| 7 | 1 |
| 8 | 2 |
| 9 | 2 |
| 10 | 1 |
实验过程中多次采集土壤样品，在实验室测定其中铵态氮与硝态氮含量；另外单次采集土壤样品用于测定矿化速率、微生物生物量及总碳含量。待植株成熟后，收获植株并烘干以测定干物质质量，随后研磨植株样品用于组织氮含量测定。如需查阅其他处理列表，请参见文件trmte38中的处理布局方案。