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Title: Certified organic herb mulching demonstration

Author
item Webber Iii, Charles
item Davis, Angela
item SHREFLER, JAMES - Oklahoma Agriculture Experiment Station
item TAYLOR, MERRITT - Oklahoma Agriculture Experiment Station
item TOWNSEND, JOSEPH - Farmer
item TOWNSEND, VICTORIA - Farmer

Submitted to: Proceedings of Horticultural Industry Show
Publication Type: Proceedings
Publication Acceptance Date: 1/29/2010
Publication Date: 3/1/2010
Citation: Webber III, C.L., Davis, A.R., Shrefler, J.W., Taylor, M., Townsend, J.L., Townsend, V.M. 2010. Certified organic herb mulching demonstration. In: Proceedings of the 29th Annual Horticulture Industries Show, January 8-9, 2010, Tulsa, Oklahoma. p. 165-166.

Interpretive Summary: The scarcity of approved organic herbicides reinforces the necessity for organic crop producers to consider the entire spectrum of weed control options rather than placing their hopes solely on herbicide applications. Weed control in conventional and organic herb production present additional challenges because herbs are often slower growing and less competitive than are typical crops. An organo-pestiphysiological (the study of organic weed control) demonstration project was conducted on certified organic land to determine the impact of mulching systems on herb production and weed control. Raised beds, 3 ft wide on 6 ft centers, were prepared on certified organic land at Lane, OK. Beds were prepared using the mulching protocols plastic mulch, rye (Secale cereale L.) straw mulch, rye straw over shredded paper mulch, and a control with no mulch. Eight herbs and two vegetables were planted, June 5, 2009, into each mulching system and all beds were irrigated as needed. The herbs included rosemary (Rosmarinus officinalis L.), German winter thyme (Thymus vulgaris L.), garlic chives (Allium tuberosum Rottler), garden chives (Allium tuberosum Rottler), bronze and green tip fennel (Foeniculum vulgare Mill.), genovese basil (Ocimum basilicum L.), roquette arugula (Eruca vesicaria L.), and bouquet dill (Anethum graveolens L.). The two vegetables were royal burgundy beans (Phaseolus vulgaris L.) and rhubarb chard (Beta vulgaris L.). Weeds were removed once a week by hoeing or hand pulling, and the time required for each crop and mulching system were recorded. The absence of any mulch (bare soil) resulted in the greatest time required to remove weeds compared to those treatments with mulches. The rye straw over shredded paper mulch inhibited weeds to the greatest extent, reducing weeding time by 80%. The plastic mulch and rye straw mulch reduced weeding by 49% and 40%, respectively, compared to the no mulch (bare soil) control. Although the weed removal time decreased with the rye straw and rye straw/shredded paper mulches, the crop yields, in general, were also reduced. Reduction in weed and crop growth may of resulted from the allelopathic impact of rye straw and/or the increase carbon nitrogen ratio in the surface soil that may have reduced nitrogen availability for plant growth.

Technical Abstract: The objective of organo-pestiphytology (the study of organic weed control) is to investigate and develop weed control strategies that are fundamental to the cropping system rather than afterthoughts to a production system. The scarcity of approved organic herbicides reinforces the necessity for organic crop producers to consider the entire spectrum of weed control options rather than placing their hopes solely on herbicide applications. An organo-pestiphysiological demonstration project was conducted on certified organic land to determine the impact of mulching systems on herb production and weed control. Raised beds, 3 ft wide on 6 ft centers, were prepared on certified organic land at Lane, OK. Beds were prepared using the mulching protocols plastic mulch, rye (Secale cereale L.) straw mulch, rye straw over shredded paper mulch, and a control with no mulch. Eight herbs and two vegetables were planted, June 5, 2009, into each mulching system and all beds were irrigated as needed. The herbs included rosemary (Rosmarinus officinalis L.), German winter thyme (Thymus vulgaris L.), garlic chives (Allium tuberosum Rottler), garden chives (Allium tuberosum Rottler), bronze and green tip fennel (Foeniculum vulgare Mill.), genovese basil (Ocimum basilicum L.), roquette arugula (Eruca vesicaria L.), and bouquet dill (Anethum graveolens L.). The two vegetables were royal burgundy beans (Phaseolus vulgaris L.) and rhubarb chard (Beta vulgaris L.). Weeds were removed once a week by hoeing or hand pulling, and the time required for each crop and mulching system were recorded. The absence of any mulch (bare soil) resulted in the greatest time required to remove weeds compared to those treatments with mulches. The rye straw over shredded paper mulch inhibited weeds to the greatest extent, reducing weeding time by 80%. The plastic mulch and rye straw mulch reduced weeding by 49% and 40%, respectively, compared to the no mulch (bare soil) control. Although the weed removal time decreased with the rye straw and rye straw/shredded paper mulches, the crop yields, in general, were also reduced. Reduction in weed and crop growth may of resulted from the allelopathic impact of rye straw and/or the increase carbon nitrogen ratio in the surface soil that may have reduced nitrogen availability for plant growth.