Recently, we received an update from a cooperator involved with our ‘Prove It’ strip trial program. SuperCal SO4 was applied at 200 lbs/acre this spring to a farm located in northern Iowa in advance of corn planting and the results so far are visually stunning.
Sulfur is increasingly being recognized as the fourth major plant nutrient after the “big three” of N, P and K. Its importance in agriculture is becoming more widely accepted as the supply of S in older fertilizer/pesticide chemistry and that supplied from the atmosphere can no longer be counted upon.
Low levels of sulfur in the soil limit the efficiency of added nitrogen, which means if you are applying more N to overcome yellow plants and slow early season growth, you throwing your money away. Nitrogen and sulfur deficiencies are commonly confused, but sulfur deficiency is easily identified by yellowing of the upper leaves (as opposed to lower, older leaves with N deficiency) and interveinal yellowing in the youngest leaves.
What should be added in this case is sulfur from a source that provides sulfate (SO4), which is the form of sulfur that plants uptake. Nitrogen and sulfur interact closely and often in the synthesis of proteins in the plant; the benefits from having the proper ratio of the two nutrients cannot be overstated on overall plant health and subsequent yield.
Here are a few photos from the farm showing control strips vs. SuperCal SO4 strips:
Fig. 1. SuperCal SO4 applied to the row on the left.
Fig. 2. SuperCal SO4 applied to the row on the right.