In reclaiming or ameliorating salt-affected soils，it is essential to go in-depth studyingsoil biological activities so as to evaluate variation of soil environmental quality and sustainability of the
amelioration measures. Highly saline-sodic takyric solonetz wastelands are distributed mainly in arid regions
in Ningxia Plain，Northwest China. This type of soils is characterized by extremely high content of sodium
and high pH，varying in the range of 9～10，and consequent poor soil structure and low saturated hydraulic
conductivity（ks＜0.1 mm d-1）. In the 0～40 cm soil layer，the average electrical conductivity of saturated
slurry extract（ECe），pH of saturated slurry（pH）and sodium adsorption ratio of saturated slurry extract
（SAR）was 10.3 dS m-1，9.4 and 38.9（mmol L-1）0.5，respectively. In the past a lot of measures have been
tried to reclaim the wastelands，however，most of them failed primarily because of the very low saturated
hydraulic conductivity of the soil. In 2009，this type of wastelands was reclaimed by cultivating wolfberry
（Lycium barbarum L.）with drip irrigation. Under the drip emitter near the plant，a pit，0.2 m in diameter
and 0.2 m in depth，was prepared and filled with alien sand for planting wolfberry in. The sand-filled pit
was to increase the area of contact between soil and water and the area of water infiltration in takyric solonetz
under drip irrigation，thus lowering water supply rate down to or approximately to saturated hydraulic
conductivity of the native soil. Besides，the sand pit maight also serve as a reservoir to hold surplus water
prior to its infiltrating into the soil and extend water infiltration time，thus ensuring water infiltration into the
soil and making reclamation of the soil possible. At the end of the wolfberry growing period in 2011（October
16th，2011），soil samples were collected intensively from soil profiles，perpendicular to the drip irrigation
belt，in fields different in wolfberry cultivation history（1 a，2 a and 3 a），covering a wide gradient of
salinity and alkalinity，for analysis of activities of soil urease，alkaline phosphatase and sucrase，which were
the enzymes，respectively，key to N，P and C recycling in soil，and of soil physicochemical properties as
well. In order to clarify any potential causal-relationships between soil enzyme activities and physicochemical
properties，correlation analysis and path analysis were performed. Results show that all the 3 enzymes were
very low in activity in uncultivated soils due to the high saline-alkali stress and low organic matter content.
After the soil was reclaimed to cultivate wolfberry with drip irrigation，soil enzyme activities increased
gradually with the cultivation going on，displaying high spatial variability within the profile. Enzyme
activities were found quite high in the root zone under the drip irrigation belt and declined outwards from root
zone. Higher soil enzyme activities in the root zone helped the crop absorb soil nutrients. Both correlation
analysis and path analysis show that soil pH is always the dominant factor affecting soil enzyme activities，
and activities of all the 3 soil enzymes decreased exponentially with pH in the range from 7.38 to 10.00
（p＜0.01）. The exponential relationship between them demonstrates that in soils quite low in pH（＜8.5），
any rise in soil pH would induce a sharp drop in soil enzymes activities. In a word，the adoption of such a
wolfberry cultivation pattern greatly improves soil biological properties of the highly saline-sodic takyric
solonetz wasteland.
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