The Effect of Rowcovers and Municipal Water or Rainwater on the Growth of Vegetable Crops in Organic High Tunnels in Kentucky

There has been an increased interest and demand in consumers’ desire for organic and locally grown food. In regions where year-round outdoor production is not possible, this demand can only be met for part of the year. High tunnels provide an opportunity for extending seasons and allow the grower to meet this consumer demand for an extended period each year.  However, unlike outdoor production, high tunnels are typically in a fixed and permanent location and do not allow for the rotation that is commonplace in organic as well as conventional outdoor production. In addition, while they do prolong the season, they are not immune to the effects of frost and winter as regions move into the deeper winter months.  Another issue with high tunnels is that the use of municipal water in high tunnels leads to a dramatic increase of salts in the soils. The build-up of chlorine, fluorine, and sodium salts due to the use of municipal water will adversely affect the soil and ultimately decrease the profitability of the high tunnel. The objective of this research was to examine the late-winter growth of three vegetable crops (arugula, spinach, and beets), with and without rowcovers, with either municipal water or rainwater for irrigation under high tunnel production. Plants were seeded in early February in four replicated high tunnels containing the treatment combinations. Plants were destructively harvested 6 weeks after planting by taking 4 samples from each plot to determine plant fresh weight and dry weight.  As expected, the three crops had different biomass production during the growth period. Water source did not significantly influence growth of any of the three plant species.  Rowcovers provided about a 40% increase in growth of the plants evaluated, likely providing protection during several cold weather events in Kentucky in February and March. Potential long term influences of these production methods will be discussed.