Temporal impacts of dryland-to-paddy conversion on soil quality in the typical black soil region of China: Establishing the minimum data set

Assessing soil quality influenced by land use changes facilitates sustainable land use and soil management. However, there are few comprehensive evaluations on the temporal impacts of dryland-to-paddy conversion on soil quality. Based on principal component analysis (PCA) and soil quality index method (SQI), a minimum data set (MDS) was established to systematically evaluate the soil quality with different duration (0, 10, 20, 30 years) of dryland-to-paddy conversion in two main soil types (meadow and albic soil) in Sanjiang Plain. Conclusions are as follows: (1) The MDS was composed of soil organic carbon (SOC), available phosphorus (AP), nitrate nitrogen (NO3--N), available potassium (AK), fine sand (FS), coarse sand (CS), and pH. (2) In meadow soil, the SQI raised significantly in the first 10 years and reached the lowest in the 30 years (p < 0.05), and the SOC and AK were the main properties affecting SQI. (3) For albic soil, the SQI was stable within 20 years and then declined significantly in the 30 years (p < 0.05). The stable SQI within 20 years was attributed to increased SOC and downward pH and AK, while declined SOC (p < 0.05) resulted in the SQI decreasing in the 30 years. The finding can enable soil quality diagnosis and sustainable development of farmland related to dryland-to-paddy conversion in the typical black soil area in the future.