wAbstract
@Soil degradation resulted from unreasonable land use has been
a serious problem in the arid region of Northwest China. This
paper seeks to understand the relationship between topsoil properties
and farming practices for land management targeting at improving
soil quality in this region. The temporal and spatial variation
of soil organic matter (SOM), total nitrogen (STN) were analyzed
with classical statistics and geostatistics methods in Linze County,
Gansu Province, an typical oasis agricultural area in arid region
of northwest China, as affected by farming practices using the
data from 1982 to 2008. The results of classical statistics indicated
that the average SOM and STN concentrations were 12.78}4.38 g
kg-1 and 0.72}0.21 g kg-1 in 1982, 13.76}4.02
g kg-1 and 0.81}0.20 g kg-1 in 2008, respectively.
The net carbon and nitrogen increased at an average rate of 0.104
Mg C ha-1 year-1 (1 Mg = 106
g) and 0.014 Mg N ha-1 year-1 in the past
26 years. Geostatistical analyses showed that the spatially related
areas of SOM and STN were expanded by effect of farming practices.
The spatial distributions of SOM and STN contents were influenced
by regional soil parent materials. Temporal variation maps of
SOM revealed a change trend was closely related to the amount
of the application of organic manures. It was concluded that the
applications of chemical fertilizers were effective for increasing
of STN, and the continuous applications of chemical fertilizers
combining with applications of organic manures (approximately
45 m3 ha-1) every other year were helpful
in accumulating soil organic carbon.
Keywords: Soil organic matter; Total nitrogen; Temporal variability;
Spatial variability; Geostatistical analysis; Linze oasisx
Abbreviation
Introduction
@Study area
@Farming practices and land management
@Soil sampling and analysis
@Statistical analysis
Results
@Descriptive statistics
@Spatial variability of SOM and STN
@Stocks change of SOC and STN
Discussion
Semivariance analysis
@Spatial distribution and impact factors
@Temporal variability of spatial distribution and impact factors
@Contributions to soil carbon and nitrogen cycling
Conclusions
Acknowledgments
References