Long-term control of the invasive annual grass cheatgrass is predicated on its biological suppression. Perennial grasses vary in their suppressive ability. We compared the ability of a non-native grass (“Hycrest” crested wheatgrass) and two native grasses (Snake River wheatgrass and bluebunch wheatgrass) to suppress cheatgrass. In a greenhouse in separate tubs, 5 replicates of each perennial grass were established for 96 d, on which two seeds of cheatgrass, 15 cm apart, were then sown in a semicircular pattern at distances of 10 cm, 30 cm, and 80 cm from the established perennial bunchgrasses. Water was not limiting. After 60 d growth, cheatgrass plants were harvested, dried, weight recorded, and tissue C and N quantified. Soil N availability was quantified at each location where cheatgrass was sown, both before sowing and after harvest. Relative to cheatgrass grown at 80 cm, all perennial grasses significantly reduced aboveground biomass at 30 cm (68% average reduction) and at 10 cm (98% average reduction). Sown at 10 cm from established perennial grasses, cheatgrass aboveground biomass was inversely related with perennial grass root mass per unit volume of soil. All cheatgrass sown at 10 cm from “Hycrest” crested wheatgrass died within 38 d. Before sowing of cheatgrass, soil 10 cm from established perennial grasses had significantly less mineral N than soil taken at 30 cm and 80 cm. Relative to cheatgrass tissue N for plants grown at 80 cm, cheatgrass nearest to the established perennial grasses contained significantly less tissue N. All perennial grasses inhibited the NO₂⁻ to NO₃⁻ nitrification step; for “Hycrest” crested wheatgrass, soil taken at 10 cm from the plant had a molar proportion of NO₂⁻ in the NO₂⁻ + NO₃⁻ pool of > 90%. In summary, a combination of reduced nitrogen availability, occupation of soil space by perennial roots, and attenuation of the nitrogen cycle all contributed to suppression of cheatgrass.

对入侵性一年生草白茅草的长期控制取决于其生物学抑制作用。多年生草的抑制能力各不相同。我们比较了非天然草（“ Hycrest”冠状小麦草）和两种原生草（Snake River小麦草和蓝枝小麦草）抑制白茅草的能力。在分开的盆中的温室中，将每棵多年生草的5个复制品放置96天，然后在两棵相距15厘米的小草种子上以半圆形的方式播种，距离10厘米，30厘米和80厘米。已建立的多年生束草。水不是限制性的。生长60天后，收获草茅草植物，干燥，记录重量，并定量组织C和N。在播种前和收获后，在每一个种植草茅的地方都对土壤氮的有效性进行了定量。相对于在80厘米处生长的虎杖，所有多年生禾草在30厘米处（平均减少68％）和10厘米处（平均减少98％）显着减少了地上生物量。从已建立的多年生草播种10厘米处，地上的草茅的生物量与每单位体积土壤的多年生草根质量成反比。距“ Hycrest”冠毛小麦草10厘米处播种的所有无草屑均在38天内死亡。播种草at之前，距已建立多年生禾草10厘米处的土壤中的氮素含量明显低于30厘米和80厘米处的土壤。相对于生长在80 cm处的草茅草组织N，最接近已建立多年生草的草茅所含的组织N明显减少。所有多年生草均抑制NO 所有的多年生草在30厘米（平均减少68％）和10厘米（平均减少98％）时都显着减少了地上生物量。从已建立的多年生草播种10厘米处，地上的草茅草生物量与每单位体积土壤的多年生草根质量成反比。距“ Hycrest”冠毛小麦草10厘米处播种的所有无草屑均在38天内死亡。播种草at之前，距已建立多年生禾草10厘米处的土壤中的氮素含量明显低于30厘米和80厘米处的土壤。相对于生长在80厘米处的植物的草茅组织N，最接近已建立多年生草的草茅所含的组织N明显减少。所有多年生草均抑制NO 所有的多年生草在30厘米（平均减少68％）和10厘米（平均减少98％）时都显着减少了地上生物量。从已建立的多年生草播种10厘米处，地上的草茅草生物量与每单位体积土壤的多年生草根质量成反比。距“ Hycrest”冠毛小麦草10厘米处播种的所有无草屑均在38天内死亡。播种草at之前，距已建立多年生禾草10厘米处的土壤中的氮素含量明显低于30厘米和80厘米处的土壤。相对于生长在80厘米处的植物的草茅组织N，最接近已建立多年生草的草茅所含的组织N明显减少。所有多年生草均抑制NO 地上草茅草的生物量与每单位体积土壤的多年生草根质量成反比。距“ Hycrest”冠毛小麦草10厘米处播种的所有无草屑均在38天内死亡。播种草at之前，距已建立多年生禾草10厘米处的土壤中的氮素含量明显低于30厘米和80厘米处的土壤。相对于生长在80厘米处的植物的草茅组织N，最接近已建立多年生草的草茅所含的组织N明显减少。所有多年生草均抑制NO 地上草茅草的生物量与每单位体积土壤的多年生草根质量成反比。距“ Hycrest”冠毛小麦草10厘米处播种的所有无草屑均在38天内死亡。播种草at之前，距已建立多年生禾草10厘米处的土壤中的氮素含量明显低于30厘米和80厘米处的土壤。相对于生长在80厘米处的植物的草茅组织N，最接近已建立多年生草的草茅所含的组织N明显减少。所有多年生草均抑制NO₂ ^-以NO ₃ ^-硝化步骤; 为“Hycrest”冰草，10cm处从植物采取土壤有NO的摩尔比例₂ ^-中的NO ₂ ^-  + NO ₃ ^- > 90％池。总而言之，减少的氮素利用率，多年生根系对土壤空间的占用以及氮素循环的减弱，都有助于抑制无茅草。