DIY Homemade Liquid Fertilizer Monitor
After seeing a in-furrow and 2X2 fertilizer monitor system at the Farm Progress Show ($10,000+), I built this DIY system with an Android tablet, an Arduino based control box, and Amazon $10 flowmeters for around $800 (in 2019).
GPA Graph on Tablet
I've simplified the fertilizer monitor app to just a graph of gallons per acre by row.
I run electric pumps for my infurrow and 2X2 systems.
I don't look at pressure. I adjust the gallons per acre by watching the monitor and adjusting the flow.