Soil nitrate and ammonium: Plant Competition Under Different Nitrogen Levels:A Garden Experiment

This garden plot experiment is located next to the E026 gardens in Field E (Old Field 44). This garden contained monocultures of major grass species from across the grassland biome of North America, and also 3 legume species (E070). The design and purpose were similar to E026, except the plots were larger. The basic experimental design consisted of growing plants in monoculture and in various competitive combinations on each of 14 different soil mixtures. In 1988 a bulldozer was used to remove 30 inches of top soil at the site. To each plot a certain amount of black dirt, ranging from 0.3 inches to 10 inches, was added. Total carbon ranged from 0.1928% to 5.63134% and total nitrogen ranged from 0.0158% to 0.4591%. The exact amounts of black soil added to each plot are described in the field operations.

Equal amounts of MgSO4, CaCO3, P2O5 \

本园圃试验位于E地块（原44号地块）的E026园区旁。该园圃种植了覆盖北美草原生物群区的各主要草本物种单作群落，同时包含3种豆科物种（E070）。本次试验的设计思路与研究目的与E026地块基本一致，仅试验小区规模更大。基础试验方案为：在14种不同土壤基质上，分别以单作及多种竞争组合模式开展植物种植实验。1988年，使用推土机移除了该地块30英寸厚的表层土壤。随后向每个试验小区施加厚度介于0.3英寸至10英寸不等的黑土。试验土壤的总碳含量范围为0.1928%至5.63134%，总氮含量范围为0.0158%至0.4591%。各试验小区的黑土精确施加量详见田间作业记录。向每个小区施加等量的硫酸镁（MgSO4）、碳酸钙（CaCO3）与五氧化二磷（P2O5）