Irrigation Water Management Considerations and Soil Moisture Monitoring Tools for High Tunnel Production
Soil moisture is generally the most limiting element in maintaining uniform plant growth and high quality produce within a high tunnel system. A full-season crop like tomatoes, peppers or cucumbers may require 15 or more inches of drip irrigation water to meet the crop's daily water usage requirements throughout the season. To operate a drip irrigation system effectively and achieve high quality yield within a high tunnel system, a daily assessment of the soil moisture within the root zone is needed.
Irrigation systems should be designed and managed to assist a producer from planting through harvest. Too much water can reduce soil aeration and cause as much trouble as not having enough water, especially during critical growth periods like pollination and fruit development. An Extension Horticulturalist from Texas A&M University points out that even small amounts of water deficiency during certain stages can be detrimental to the plants. This deficiency can occur even before visible wilting occurs. He also mentions that even slight water deficiencies can cause slowed growth rate, lighter weight fruit and, in tomato, blossom end rot. Sanders from North Carolina likewise states that when soil moisture is allowed to drop below the proper level, the fruit does not expand to produce maximum size before it ripens, thus reducing yield and, if moisture is allowed to fluctuate too much, blossom end rot can occur and fruit is no longer useable.