What is not "logical" about cover crops?

"Illogical Captain" ...Cover Crops in New Mexico Vineyards?

 Dr. Mark Greenspan begins his recent article on cover crop selection (Wine Business Monthly, October 2019, https://www.winebusiness.com/wbm/ ) by describing what species of cover crops to utilize in vineyards. He restricts his comments for application/consideration in “wetter growing regions”, as dry winter regions are “challenging, or borderline impossible” places to establish cover crops. Dr. Greenspan continues: “…using additional water to grow a cover crop that sucks up more water from the ground in a dry climate does not seem desirable or logical”. Dr. Greenspan lists the many benefits of cover crops in vineyards: mitigation of soil compaction, erosion reduction, improved water infiltration, improved soil organic matter, increased soil aeration, providing substrate (food?) for soil microbiota, moderating vineyard microclimate and reduction of dust and mites, adding nitrogen to the soil (legumes) and the support of beneficial insects…not to mention the aesthetic appeal of flowering cover crops. These cover crop benefits sound like they are,... well, beneficial.

As described above, vineyard cover crops offer a potentially long list of benefits. Is it “illogical” to apply some water to gain these benefits? The use of such “illogical” cover crops in “dry regions” begs the question: Does the additional water required by the cover crop justify its benefits? As one trained to be a professional skeptic, I’m not sure. Consequently, I have adopted the use of cover crops in the experimental vineyard at Los Lunas ASC to begin to explore this (Figure 1).The cover crop being used this fall at Los Lunas is  triticale or Triticosecale, a hybrid of wheat (Triticum) and rye (Secale) and was seeded on 9/25/2019 with a flood irrigation applied on 9/26/2019. Ten days later, the triticale was up and growing...covering the row middles (Figure 2). The plan is to allow it establish and cover the row middles until about March and then overseed with a native grass and pollinator mix.

This question, or comparison of cost:benefit ratio deserves quantification and a scientific accounting here in New Mexico. NMSU Viticulture PhD graduate student, Ms. Jacqueline Cormier, has established several cover crop plots in the Malbec vineyard at Fabian Garcia ASC in Las Cruces, to systematically investigate this cover crop cost:benefit ratio question. Bear in mind that several New Mexico winegrowers have been using cover crops for years, and clearly believe their benefits are worth the cost and effort. We look forward to Ms. Cormier’s empirical results. I suggest you go to the Wine Business Monthly website and read Dr. Greenspan's article for yourself.

As to Dr.Greenspan's description of some regions as "challenging or borderline impossible" to support cover cover crops, what about those two words is unfamiliar to anyone who has successfully (or not so successfully) grown wine grapes in New Mexico?

Figure 1. Application of flood irrigation after seeding row middles with triticale at rate of about 50 lbs /acre

Figure 2. Triticale growing in experimental vineyard row middles at NMSU Agricultural Science Center, Los Lunas, NM