Nature's Call

Manganese in your Garden Soil

A growing problem in today's gardens is having sufficient nutrients beyond the big three of nitrogen, potassium and phosphorous. An additional nutrient that's often lacking is manganese. A shortage of manganese means problems in water hydrolysis for photosynthesis. Basically, manganese is critical in splitting water molecules into hydrogen and oxygen. When problems occur here, photosynthesis is either blocked or reduced.

It doesn't really matter if you have all the other ingredients for photosynthesis (sunlight, water, carbon dioxide, sunlight, chlorophyll. Without enough manganese, it becomes the choke point that hinders or stops photosynthesis.

Ironically, manganese, or a shortage of it, can easily be determined by examining the plant leaf veins. They should be at least as dark as the area between the veins. If the veins are lighter than the areas between them, you have a direct indicator that manganese, or lack thereof, is a problem.

A new problem since the '90s is Roundup. This chemical is a chelator — it binds with elements and makes them unavailable. As such, it is possible to have sufficient manganese in the soil, but roundup is making it unavailable. How serious is this problem? We're spraying 300 million pounds of roundup on crops every year. 75% of our rainwater contains roundup.

How serious is this in your gardens? Well, it's impossible to say but 90% of surveyed farms recently had manganese deficiencies. Regardless of whether this problem is occurring in your gardens, it's almost guaranteed to be a problem in the future. Further, if phosphorous is low or not readily available, manganese is almost certainly going to be deficient. Cover crops and crop diversification can help to alleviate this problem.

A continuing recommendation for gardeners is to go beyond a standard soil test (great for yards) and get an expanded soil test for your gardens.