The experimental site is located in a warm and arid region
with a mean annual precipitation of 63 mm and an annual
mean long-term average temperature of 23 C. In 2009, the
year this experiment was conducted, the annual precipitation
and mean temperature were 98 mm and 20 C, respectively.
These values differed considerably from the long-term average.
Precipitation and mean temperature were, respectively, above
and below the long-term average. The preceding crop was forage
sorghum (Sorghum bicolor), and there was no history of
sewage application at the site of the experiment