Dr. Bruce Bugbee Appreciation

[Cactus]

Case # 1. Assume a transpiration to dry-mass growth ratio of 300:1 and a desired K concentration in the plant of 4% (40 g kg-1). For every kg of plant growth, 300 Liters of solution went through the plant, so there must be 40 g of K in 300 Liters of refill solution, or 0.133 g L-1. The molar mass (atomic weight) of K is 39 g mol-1. The refill solution must have 0.133 / 39 = 0.0034 moles L-1 of K in it, or 3.4 mM K.