I just started gardening and some of the first Zucchini seeds I have sowed have emerged. The zucchini Cotyledons looked nice and green and seemed quite ok. Several days after the first one emerged, I found the Cotyledons wilting. The plant looks like it is dead. The soil dries very quickly in the sun, the rows are around 6 - 8" tall and flat topped. I water them often to keep the soil moist at the surface due to this reason as I have not figured out what kind of mulch I will be using.
Soil test results
Soil pH: ~5.5 - 6.0
What am I doing wrong? It's hard to tell if I am overwatering, since the soil can dry 2 - 3 inches a day without watering; I try to soak the soil mid day because of the fast evaporation.