A one-year continuous field monitoring study at fixed observation positions was conducted on a sand belt site in the southeast edge of Mu Us desert land

with continuous monitoring of soil water potential and temperature. With the sand surface first reshaped into furrow-and-ridge form

the in-situ field test had 3 treatments

i.e.

the ridge section one was covered with plastic membrane plus weed-blocking geotextile (MB); section two covered with weed-blocking geotextile only (DB); and section three exposed or uncovered to serve as the blank contrast (CK). Soil water potential and temperature were monitored using MPS-6 probes at 5

15

30 cm below the furrow surface

at 30 minute intervals

along with meteorological data above the soil surface. Results showed that: (1) The daily variations of soil water potential under the 3 treatments all showed characteristics of a Cosmic function

the daily soil water potential at the 5 cm depth was the most varied in the three groups

varying between -600 and -120 kPa

and showing MB > CK > DB. At the 15 cm depth

the value was higher with smaller variation between -180 and -90 kPa

showing DB > CK > MB. At the 30 cm depth

the soil water potential is virtually stable

with high water potentials for MB and DB stabilized at about -100 kPa

and much lower stable potentials for CK at about -285 kPa; (2) The annual variation of soil water potential showed two valleys

including the freezing-thawing period in the winter and the strong evaporation period in the summer. The annual averages among the 3 groups show that: at 5 cm MB > CK > DB

at 15 cm DB > CK > MB

and at 30 cm MB=DB>CK. The main reasons are that under the condition of MB and DB

the accumulated heat in the soil during the day time is higher

and the upward temperature gradient at night is higher

then the soil water at 15 cm depth moves up and accumulates under the surface membrane and it would be evaporated without the membrane. Therefore

the water potential at 5 cm below the surface is larger

while the water potential at 15cm is smaller. At the same time

under the condition of MB

the rainfall infiltration depth is the largest

so is the surface water content; Under MB and DB conditions at 30 cm

the water potential is approximately the same

but both are larger than that under CK. The predominant reason is that the rainfall in this area is small

and most rainfall cannot infiltrate to 30 cm depth without mulching; (3) When the 3 groups were analyzed for the total 0-30 cm soil layer

the soil water potential was greatly affected by relative humidity and wind speed of the atmosphere during freezing-thawing period. In the non-freezing-thawing period

soil water potential was most influenced by wind speed

followed by atmospheric temperature and relative humidity. It can be concluded that the moisture retention effects at 5 cm soil depths was better with MB treatment

while DB was better for 15 cm soil depth

and both MB and DB were better for 30 cm soil depth. These results could be used as a reference for sand fixation and revegetation in the desert area.