The Government Department responsible for advising on corn growing in my region suggests the following:
Recommendation 1: use between 500 and 700 mm of irrigation
I applied 172 mm washing machine water
There was also 282 mm of rain during the crop (with 120 mm coming in just 2 days much of which ran off the surface). That makes a total (irrigation plus rain) of 454 mm.
Recommendation 2: Apply 200 kg N fertiliser (50 kg at planting, 120 kg at 3 weeks and 30 kg at 5 weeks).
I applied no fertiliser or manure at planting. I measured 500 ppm nitrate in the deeper wetting front detector one week after planting. Using calculations I will not give you here – that means I already had more than 200 kg of N in the top 60 cm of my soil. But I did apply 10 kg N/ha at both weeks 4 and 7. Total N fertiliser application 20 kg/ha.
Recommendation 3: Expect a yield of 12 to 22 t/ha of fresh corn (in husk)
My yield was 22 t/ha but some of the cobs were not properlly filled with kernels (the second ones on the plant), which dropped the marketable yield to 20 t/ha
Good yield with not much water and very little fertiliser.
But wait till you see what the washing machine water did to the soil pH and the level of phosphorus!
Actually I’m monitoring the adjacent bed which was planted one month later. I’m using a pure sodium chloride solution – to the same electrical conductivity as the washing machine water - and getting very different results.