Abstract:
Healthy soils support diversity of terrestrial vegetative ecosystems. However, soil quality
degradation often led to affect soil productivity and unable to support sustainable biomass
production. The study was conducted to better understand the relationship between pasture
biomass yields and soil quality in the semi-arid natural grasslands of the Shohada-Valley,
Western Azerbaijan Province of Iran. With the identification and delineation of the mapping
units, a composite base map was prepared to combine maps of four directions, five classes of
slope degrees, and several vegetation types using geographic information system (GIS) on a
1:50,000 scale. Composite soil sample was randomly taken from 0 to 30 cm depth and selected
soil chemical and physical properties were determined by using standard methods of analysis.
The pasture yield, consists of herbaceous plants and small shrubs at their flowering stage, was
determined. Principle Component Analysis (PCA) and step-wise multiple regressions were
performed to identify soil quality (SQ) core indicators related to biomass production. Based on
28 delineated mapping units, the mean values of soil landscape, stability, infiltration rates, and
nutrient indices were calculated as 0.8, 76.9, 57.1 and 69.1, respectively. Mean total biomass
yield was determined 1.54 Mg/ha. By using the PCA, three components were identified having a
latent root more than one, which accounted for 78% of the SQ variability. The indicator variables
for calculating the soil quality index (SQIndex) werelandscape organization index (LOIndex),
nutrient cycling index (NCIndex), and salinity and compaction (bulk density, ?b) were determined.
The calculated SQIndex significantly and linearly accounted for 64% of variability in measured
pasture yield. Likewise, the predicted pasture yield based on SOindex significantly and linearly
correlated with field-measured pasture yield, by accounting for 63% of the variability or viceversa.
Results suggested that that the SQindex model is very usable to provide a reliable estimation of pasture biomass production in the semi-arid and cold semi-steppe habitats for such regions in
the world. |
