Cover Crops as Killed Mulches, An Alternative in Sustainable Agriculture in Semi-Arid New MexicoShiella Merriman-Parr *smerriman_parr@hotmail.com, E.M. Silva, Constance Falk

METHODS & MATERIALS:Six cover crop cultivars were planted into 101.6 cm beds in a split-plot design, with crop cold-hardiness as the whole plot factor and cover crop variety as the sub-plot factor. Each replication consists of three beds (60.39 cm2), with a total of three replications per cultivars.

Three cold-sensitive cultivar crops (Summer Cover Crops) were planted in September 2005 and killed by cold temperatures in November 2005Three cold-tolerant cultivars crops (Winter Cover Crops) were planted October 2005 and killed using glyphosate in March 2006

Cover crops were mowed in March 2006 and residues left on the soil surface Chile peppers (Capsicum annuum, cv. ‘AZ-20’) were transplanted into the center of each bed during April 2006Irrigation for each treatment was accomplished through subsurface irrigation and quantified using water meters for each cultivar planting. Scheduling of irrigation was determined by continual monitoring of soil moisture levels at the 20 cm depth using Frequency Domain Reflectrometry.Weed populations were monitored at a bi-monthly basis by quantifying specific weed species contained within a 1m X 1m quadrat located at random positions in each replication. Weed management was accomplished by hand-hoeing throughout the season.Chile peppers were harvested by hand in July 2006 and yields were determined for each replication.

RESULTS:The performance of the chile crop on the cold-tolerant cover crops was poor due to issues with the cover crop root systems infiltrating the irrigation system. Thus, data is not reported.Weed populations, although not significantly different, did show a decreasing trend in the Sudex cover crop early in the growing season. The lablab bean and cowpea cover crops did not suppress weed populations.The amount of water required to supply the chile crop with optimal soil moisture was not significantly different between the cover crop treatments.Yields of chile peppers grown on cover crops were not significantly different than chile grown on bare ground.

INTRODUCTION:

Chile crops grown in New Mexico are challenged by abiotic stresses throughout the growing season. In New Mexico, water is a diminishing commodity, and providing adequate irrigation to the chile crop for optimal yields is a growing concern in the face of drought and increased population growth (TWRI, 2005). High winds and heavy rains on the open landscape contribute to high amounts of soil erosion, with blowing sand in the spring often causing physical damage to the chile crop. Cover crops used as mulches on the soil surface offer a potential tool to mitigate these issues. Cover crops have been shown to provide multiple benefits to agricultural systems including controlling erosion, conserving soil moisture, suppressing weeds, improving soil physical properties, increasing macro-fauna activity, increasing soil organic matter, and increasing water infiltration (Findeling, 2003). Specific cover crop species may be better suited for certain crops through their varying effects on irrigation, weed management, and pest complexes. This work was initiated in order to investigate the use of cover crops in chile production and their effects on the chile agroecosystem.

References

Findeling, A., Ruy, S., Scopel, E. (2003). Modeling the Effects of a Partial Residue Mulch on Runoff Using a Physically Based Approach. J. Hydrology, 275, 49-66.TWRI, T. W. R. I. (2005). TWRI: Rio Grande Basin Initiative. Retrieved October 1, 2005

CONCLUSION:From the first year’s data, the integration of winter-killed mulches into chile production systems appears to have no negative effects on green chile yields.The use of a cover crop such as Sudex with increased biomass and residue may be useful in minimizing early season weed populations. Further work will be performed to replicate this data in 2007 and further investigate the effects of these mulches on the aforementioned factors as well as on insect populations and specific soil moisture retention.

ACKNOWLEDGEMENTS:

Thank You to the Rio Grande Basin Initiative for the funding of this project.

Thank You to Jeff and Christine Herrick for use of their land and their continued support of this project. LabLab Bean Sudex

Cowpea

OBJECTIVE:To evaluate and quantify the effects of using several species of cover crops as killed mulches on chile production, including soil moisture, weed populations, and yield.

130.1

SUMMER:CV1-LabLab bean (Dolichos lablab L.) CV2-Sudex (Sorghum-Sudan hybrid) (Sorghum sudanense (Piper)) CV3-Cowpea (Vigna unguiculata (L.) Walpers ssp. Unguiculata) *WINTER:CV1-Winter rye (Secale cereale) CV2-Fall manure mix:winter rye (Secale cereale L. cv Puma), field peas (Pisum sativum),

ryegrass (Lolium rigidum), crimson clover (Trifoliumin carnatum L.) and hairy vetch (Vicia villosa Roth)

CV3-Austrian winter pea (Pisum sativum var.Austrian) Control -BG-Bareground

CV3CV1BGCV2CV3CV2CV3CV1BGCV2CV1BG

CV3CV1BGCV2CV3CV2CV3CV1BGCV2CV1BG

Winter Cover Crop Meters

Summer Cover Crop Meters

Irrigation Pump

59,476

45,068

49,843 51,518

0.00

10,000.00

20,000.00

30,000.00

40,000.00

50,000.00

60,000.00

Bare Ground

LabLab Bean

Sudex

Cowpea

*values of a column designated with the same letter are not significantly different according to Fisher’s LSD (P<.05)

a*

aa a

Cover Crop

Yie

ld (

Pou

nd

s/A

cre)

2006 Chile Yield

0

10

20

30

40

50

60

70

80

90

April (Pre-Plant) May (Vegetative Stage) J une (ReproductiveStage)

J uly(Maturation/Harvest)

Bareground

LabLab Bean

Sudex

Cowpea

b

aba

a

b

ab

b

a

*values of a column designated with the same letter are

not significantly different according to Fisher’s LSD (P<.05)

a

a

a

a

aaa*

a

Month/Crop Development

Tot

al W

eed

Cou

nt

Weed Density

0.0

1000.0

2000.0

3000.0

4000.0

5000.0

6000.0

May (Vegetative Stage) June (Reproductive Stage) July (Maturation/Harvest)

Bareground

LabLab Bean

Sudex

Cowpea

*values of a column designated with the same letter are not significantly different according to Fisher’s LSD (P<.05)

a a

a

a*

aa

a

a

a aa

a

Tot

al G

allo

ns

Month/Crop Growth Stage

Monthly Irrigation Totals

A

B

C

Plant & Environmental Sciences