df <- data.frame(ID = c('SS940426', 'SS940442', 'SS952672'),
                 Estación = c('200510020012', '200380030004', '200180010105'),
                 control= c(1, 2, 3),
                 Peso=c(250,380,410),
                 campo1= c(520,982,988),
                 campo2= c(682,987,988),
                 campo3= c(720,963,999))


df

      ID         Estacion       Control    Peso    Campo1  Campo2  Campo3
1  SS940426    200510020012      1          250      520    682    720
2  SS940442    200380030004      2          380      482    987    993
3  SS952672    200180010105      3          410      588    688    999

ID         Estacion       Control    Peso
1  SS940426    200510020012      1          250
2  SS940426    200510020012      2          520
3  SS940426    200510020012      3          682
4  SS940426    200510020012      4          720
5  SS940442    200380030004      1          380
6  SS940442    200380030004      2          482
7  SS940442    200380030004      3          987
8  SS940442    200380030004      4          993
9  SS952672    200180010105      1          410
10  SS952672    200180010105     2          588
10  SS952672    200180010105     3          688
10  SS952672    200180010105     3          699

df1<-melt(DF, value.name = ????, id.vars = c("control","peso")
     +                   variable.name = ????)