Nutrient Use In High Tunnel Production, Penn State Experience

Lengthening the growing season offers growers an opportunity to extend the period for producing and harvesting crops and, therefore, for capturing profits.  At Penn State University, the High Tunnel Research and Education Facility at Rock Springs, Pa was initiated in 1998 to study the use of high tunnels as an option for season extension of vegetable and fruit crops.  The facility houses over 40 high tunnels, the majority of which are 17 x 36-ft and constructed using the Penn State design.  The soil type at the facility is a Hagerstown silt loam.  One production issue encountered at the facility is the impact of fertility management on soil quality and plant growth because of the unique environment created within the high tunnels.  High tunnels exclude environmental factors (i.e. precipitation, excess wind) that assist in decomposition and/or mineralization of organic nutrient sources.  Additionally, the environment and cultural practices limit leaching which results in a build-up of salts that can negatively affect soil organisms and plant growth, regardless of using organic or inorganic nutrient sources.  This has negatively impacted the growth of several crops as illustrated by a two-year study on bell peppers.  The high tunnel environment also tends to favor vegetative and reproductive plant growth resulting in a higher need for plant nutrients than recommended by production guides for certain crops.  Brambles are one such crop where potassium deficiency has been documented with tissue analysis.  Fertility management protocols for production in high tunnels is an area warranting further study and will be different from open field production owing to the unique environment within high tunnels.