Data from: Barley cover crops outperform brown mustard for early-season weed control in New Mexico chile pepper

Barley (Hordeum vulgare L.) and brown mustard [Brassica juncea (L.)
Czern.] are winter cover crops known to produce allelochemicals that
suppress plant growth. Incorporating barley or brown mustard residues into
the soil before planting a spring-seeded cash crop may suppress
early-season weeds in the cash crop; however, the comparative levels of
weed suppression offered by barley and brown mustard cover crops
incorporated into soil have not been determined. This study analyzed the
relative capacities of barley and brown mustard cover crops to suppress
early-season weeds of spring-seeded chile pepper (Capsicum annuum L.).
Reductions in weed density or hand-hoeing time as a result of barley
and/or brown mustard cover crop treatment were determined in two chile
pepper fields in New Mexico over two growing seasons. For cover crop
species that suppressed weeds in multiple site-years, a controlled
environment study clarified possible growth stages adversely affected by
determining the effects of cover crop–amended soil on the germination and
seedling development of Palmer amaranth (Amaranthus palmeri S. Watson).
Field study results indicated barley reduced early-season weed densities
of chile pepper by up to 80 % compared with the noncover control. Barley
also reduced hoeing time in 3 of 4 site-years without affecting chile
pepper fruit yield. Mustard cover crops reduced weed density in only 1
site-year (56 % reduction relative to noncover control) and did not
decrease hoeing time. The controlled environment study indicated that soil
amended with barley slowed germination of A. palmeri without inhibiting
seedling development. The results of this study indicate that a barley
cover crop is more effective than brown mustard for early-season weed
control of chile pepper in the southwestern United States.