Land Retirement Demonstration Project

THE BERM AND MYCORRHIZA TRIAL

Overview

The Berm and Mycorrhiza Trial was developed to investigate methods of enhancing topography and of facilitating recovery of the soil's mycorrhizal communities. Two factors were considered: 1) berm "architecture" {i.e., the manner by which berms were constructed}; and 2) mycorrhizal inoculation. Two methods of berm construction were compared. The first method ("dressed" berms) approximated that used to construct berms in the HRS trial; in the second method ("rough" berms), berms were constructed using just the border maker and were not compacted. Commercially purchased mycorrhizal was applied to half the plots.

Plot size was approximately 0.2 ha (0.5 ac); each treatment was replicated five times. Each plot contained seven berms; berms were evenly-spaced on approximately 9.1 m (30 ft) centers and were oriented east to west. A seed mixture of thirteen native species was imprinted. Installation of the trial began in mid-February, 2002. Because of the late seeding date and the low rainfall, the plots were irrigated twice during the course of the experiment (21 March and 20 April, 2002). Data (percent cover and species composition) were collected from 15 quadrats (35 x 70 cm) per plot. Vegetation monitoring was conducted in mid-May 2002 (May 6, 11-12, 14, 17-20).

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Table 1. Species planted in the Berm and Mycorrhiza Trial, including Family, common name, life-form, and seeding rate. Seeding rates are expressed in gross (i.e., not lbs. pure live seed) pounds per acre.

Taxon	Family	Common Name	Life-form	Seeding Rate
Allenrolfea occidentalis	Chenopodiaceae	iodinebush	shrub	3.00
Atriplex polycarpa	Chenopodiaceae	allscale saltbush	shrub	3.00
Atriplex spinifera	Chenopodiaceae	spinescale saltbush	shrub	2.25
Bromus carinatus	Poaceae	California brome	perennial herb	4.50
Frankenia salina	Frankeniaceae	alkali heath	perennial herb	0.75
Heliotropium curassavicum	Boraginaceae	seaside heliotrope	perennial herb	0.75
Hemizonia pungens	Asteraceae	common spikeweed	annual herb	0.15
Isocoma acradenia	Asteraceae	goldenbush	shrub	1.00
Lasthenia californica	Asteraceae	California goldfields	annual herb	0.75
Leymus triticoides	Poaceae	creeping wild-rye	perennial herb	3.00
Sporobolus airoides	Poaceae	alkali sacaton	perennial herb	1.50
Suaeda moquinii	Chenopodiaceae	bush seepweed	sub-woody perennial	0.75
Vulpia microstachys	Poaceae	small fescue	annual herb	3.00

Page created: March 1, 2005; Last updated: Dec. 20, 2005