Evaluation of the soil quality of the lands under irrigated wheat cultivation in Tabriz plain

Soil has various tasks or functions, including the ability to produce crops, store carbon, store water, cycle nutrients and purify water. Soil functions have a high correlation with soil quality. Soil quality indices are often regional and to determine it, it is not possible to consistently use a set of idicators and indices in all regions. In this research, Additive Soil Quality Index (SQIa), the Weighted Additive Soil Quality Index (SQIw) and the Nemero Soil Quality Index (NQI) and the effect of effective characteristics on soil quality in surface soil (0-30 cm) and in the yield of 206 wheat field of East Azarbaijan Province (Tabriz Plain) in 2017 was investigated by measuring physical and chemical properties of soils and wheat grain yield. Organic carbon, bulk density, aveilble potassium and aveilble phosphorus and electrical conductivity were selected as The minimum data set (MDS) using principal component analysis (PCA). Then SQIa, SQIw and NQI were determined using TDS and MDS. The results showed that there is a correlation between wheat yield and soil quality indices using MDS (r=0.60-0.63) and using TDS (r=0.56-0.60) also there was a significant correlation (p <0.01) between the use of TDS and MDS in NQI (r=0.81), SQIw(r=0.84) and SQIa (r=0.88) (p<0.01). Therefore, all three investigated indices are suitable for the study area and using MDS is more suitable than the method of using TDS due to relatively higher correlation and number of features and lower cost.