if(!require(remotes)) install.packages("readr")
library (readr)
github="https://raw.githubusercontent.com/agronomy4future/raw_data_practice/refs/heads/main/SOC.csv"
df=data.frame(read_csv(url(github),show_col_types= FALSE))

print(head(df, 5))
  Column Row  SOC
1      1   1 1.45
2      2   1 1.60
3      3   1 2.34
4      4   1 2.20
5      5   1 1.80
.
.
.

ggplot(df, aes(x=Column, y=Row, fill=SOC)) +
  geom_tile(color="white") +
  geom_text(aes(label=round(SOC, 1)), color="black", size=3) +
  scale_x_continuous(breaks=1:19) +
  scale_y_continuous(breaks=1:13) +
  scale_fill_gradientn(
    colours=colorRampPalette(brewer.pal(9, "Blues"))(100),
    limits=c(0, 4),  breaks=seq(0, 4, by=1), name="SOC", na.value="white") +
  labs(x="Row", y="Column") +
  theme_classic(base_size=15) +
  theme(legend.position="right",
        legend.title= element_text(size=12),
        legend.key.size=unit(0.5,'cm'),
        legend.key=element_rect(color=alpha("white",.05), fill=alpha("white",.05)),
        legend.text=element_text(size=12),
        legend.background=element_rect(fill=alpha("white",.05)),
        panel.grid=element_blank(),
        panel.border=element_rect(color="black", fill=NA, linewidth=0.5),
        axis.line=element_line(linewidth=0.5, colour="black"))

---