By Blake Jackson
High tunnel growing systems can significantly boost profitability for farmers, but they also present challenges, particularly concerning soil health.
One major issue is the accumulation of soluble salts, which can arise from excessive fertilizer applications both organic and inorganic without adequate water for leaching.
Over time, elevated salt levels can stress plants, leading to decreased crop vitality and yields.
When soluble salt concentrations in the soil become too high, moisture may move from the plant roots into the surrounding soil, creating conditions similar to drought.
Symptoms of high salinity include stunted plant growth, reduced yields, blossom end rot, and even plant death in severe cases.
Despite many growers routinely testing their soil, few check for soluble salt levels, which is often an optional analysis.
In a study by Penn State, a Pennsylvania grower faced yield issues with their high tunnel tomatoes. Despite receiving advice to increase nutrient inputs, their soil tests revealed already excessive nutrient levels.
Further testing indicated a soluble salt level classified as "strongly saline," which could drastically reduce yields, even with sufficient nutrients present.
Unlike open fields where natural rainfall can leach away salts, high tunnels create a controlled environment that may lead to salt accumulation. Growers facing high soluble salt levels have a couple of options: relocating the high tunnel or temporarily removing its cover to allow precipitation to leach the salts.
An effective and less labor-intensive method is to actively leach salts by applying water. Guidelines suggest that to achieve a 50% reduction in salts, approximately 6 inches of water is needed, while more significant reductions require greater volumes.
Overhead irrigation is recommended for this process, and simple methods, such as placing containers to collect water, can help gauge the amount applied.
While addressing soluble salt levels is crucial, growers should also be aware of other yield-limiting factors, such as plant-parasitic nematodes and soil pathogens, which may arise from limited crop rotations. Effective management practices, including leaching, are vital for maintaining healthy high tunnel systems.
Photo Credit: pexels-greta-hoffman
Categories: Pennsylvania, Crops