More than half of the acreage in the Antelope Valley is used for production of carrots, onions, or potatoes. These crops are grown on the land once a year and in many cases the land has to remain fallow during windy time periods for land preparation reasons or simply because the grower could not fit the land into crop rotation. There are a wide variety of cover crop options available to growers depending on the planting situation.

Mustard cover crops have been known to reduce populations of soil borne pests such as nematodes and diseases. Research from 2002-2003 showed that mustard grown prior to carrot planting increased carrot yields. On the other hand disease (cavity spot) levels were higher in carrots from the mustard plots compared to those from the fallow control plots without a mustard crop. These results could have been due to the six month period of time between mustard incorporation and carrot planting. During this time the pythium sp. that causes cavity spot could have recolonized in the mustard residue in the mustard plots. UCCE is currently re-evaluating these parameters as they pertain to mustard cover crops.

Warm season legume cover crops can be grown during the summer months. Legumes fix nitrogen in the soil which is an added benefit of growing warm season cover crops. In 2003 several varieties of cow pea were compared to Sesbania, or Colorado River Hemp, and evaluated for their performance and nitrogen contribution to the soil. Although the cowpeas looked poor visually in the field, the top performing cowpea variety Iron Clay contributed approximately 160 lbs of N to the soil.

Cereal grains can be grown as a low cost cover crop. These covers are usually acceptable when land is going to remain fallow for a year or more and there are no other cropping options. Solum barley performed very well in desert conditions under six to seven inches of rainfall in 2002-2003.

Results from these trials were reported in the 2003 High Desert Research Results. You may contact Grant Poole, UC farm advisor for this publication.