The HeritageQuest US census index at the Boston Public Library doesn't show an 1860 entry for David Risser, But it does have an entry for a "Javier Risser" born in Bavaria. Now Javier is a Spanish name and therefore rather unusual for a Bavarian immigrant, raising the possibility of some sort of transcription error.

Here's the original census sheet entry:

One could easily convince oneself that this is actually "David Risser" with a fancy "D" and not "Javier" if it weren't for other clear instances of J's on the page:

Jacob Jacob Jacob June and his own initial
Jacob Jacob Jacob June and his own initial

As there is a John S. Gilmore living in this town, it seems likely that he is the census taker and that the signature is this "J. S. Gilmore". Compare these J's with Gilmore's D's, including the name David:

David Dorothy Day Laborer
David Dorothy Day Laborer

Combining one of Gilmore's J's with the "avid" from his "David", I get something that looks an awful lot like what he actually wrote:

J + avid actual David
I think the most honest transcription you can give of this is that Gilmore wrote "Javid". The best interpretation that I can give of what he wrote is that he probably meant to write "David". This is reinforced by a comparison of the this family's 1860 census with that of David Risser in 1870 and1880:

1860, Lee Co, Iowa 1870, Lee Co, Iowa 1880, Otoe Co., NE
Javid Risser 34 M Bavaria Risser, David 44 M Bavaria Risser, David M 54 Germany
Christina 31 F Bavaria Christina 41 F Bavaria Christina F 51 wife Germany
Wilhelmia 4 F Iowa Wilmina 14 F Iowa
Elizabeth 1 F Iowa Eliza 11 F Iowa Eliza F 21 dau Iowa
Louis 9 M Iowa Louis M 19 dau* Iowa
William 7 M Iowa William M 17 son Iowa
Helina 4 F Iowa Hellena F 14 son* Iowa
Adelia F 7 dau NE

And so we find that David and Javid have remarkably similar families. I therefore feel justified in concluding that Javier = Javid = David Risser.