ReducingEragrostis lehmannianapopulations by preparing seedbeds with unconventional tillage implements and seeding in a semiarid grassland

Abstract

The invasion of Eragrostis lehmanniana Nees in rangelands of Chihuahua, Mexico, has resulted in a need for revegetation to recover lost forage productivity. Thus, new knowledge on generating alternatives to improve these invaded grasslands is of great importance. This study evaluated seedbeds prepared with unconventional tillage implements and seeded with a grass mixture to reduce the plant density of E. lehmanniana while increasing the productivity of an invaded semiarid grassland of Chihuahua. The unconventional tillage implements were: Rangeland Harrow, which were used to prepare the Striped Harrowing and Full Harrowing seedbeds; Rangeland Rehabilitator, which prepared a Deep-Stingray Subsoiler seedbed; and a Tandem-type Aerator Roller, which prepared a Double-Digging Aeration seedbed. An area without tillage was left as control. The seed mixture was composed of Bouteloua gracilis (Willd. ex Kunth) Lag. ex Griffiths, var. Hachita (25%); Bouteloua curtipendula (Michx.) Torr., cultivar-6107 Kansas (25%); Leptochloa dubia (Kunth) Nees, var. Van Horn (5%); Eragrostis curvula (Schrad.) Nees var. Ermelo (40%), and Sorghum almum Parodi (5%). The experiment was conducted during four years and the evaluation started at the second year. Plant density and dry matter (DM) production was evaluated per species. In the control plot, the plant density of E. lehmanniana increased approximately 180% from the 2nd to the 4th year (18 to 50 plants m-2). The use of unconventional tillage implements for seedbed preparation and the inclusion of E. curvula in the seed mixture, decreased E. lehmanniana density in more than 50% and increased DM production in more than 100%. Considering the whole experimental period an all the prepared seedbed treatments, E. curvula had the highest establishment and DM production of all the seeded species. The native species B. gracilis, B. curtipendula and L. dubia had a poor establishment in all the prepared seedbeds.

Vegetation Response to Removal of Plant Groups and Grass Seeding in a Microphyllous Desert Shrubland: A 4-Year Field Experiment

“…In addition, seeding of this native grass led to the highest forage production after 4 years of grazing exclusion (1147% more forage than CON), which is higher than the 1213 kg ha −1 reported by Lair and Redente [23] for this grass seeded in combination with other native graminoids or <1000 kg ha −1 as monoculture [14,24]. Other studies had poor results in establishing B. curtipendula by the end of the third [25] or fourth growing season [26] due to low rate of plant establishment in arid ecosystems [27].…”