Characteristics of soil fertility quality and minimum dataset for yellow-mud paddy fields in Fujian Province

In modern agricultural production, the quality of soil fertility is crucial for the crop productivity.Yellow-mud paddy fields constitute one of the main types of medium-to-low yield fields in Fujian Province, which accounts for about 30% of paddy fields in the province.In order to determine key limiting factors, evaluate the quality of soil fertility and implement targeted improvement measures, 28 soil characteristics of 20 pairs of typical surface soil samples from yellow-mud paddy fields and high-yield grey-mud fields in the neighboring and the same landscape units in Fujian Province were compared.Differences in soil properties between the two soils and the causes were systematically analyzed and the minimum data set (MDS) for assessment of the quality of soil fertility in yellow-mud paddy fields established using principal component analysis and other methods.Using the weighted index method, the soil fertility quality index (SFQI) from MDS and the important data set (IDS) constituted on the basis of significantly different factors. The results showed that compared with grey-mud paddy fields, the content of organic matter in yellow-mud paddy fields was less by 19.1% and the contents of total nitrogen, total phosphorus and total potassium were less respectively by 14.8%, 29.9% and 25.4%. Also the contents of available nitrogen, available phosphorus and available potassium were less respectively by 17.8%, 56.7% and 39.3%.CEC and the contents of exchangeable calcium, exchangeable magnesium were less respectively by 12.9%, 50.6% and 30.8%. While the contents of available iron, available boron and available zinc were less respectively by 25.6%, 33.3% and 44.1%, the contents of clay < 0.001 mm and bulk density were higher by 20.8%, 25.6% and 12.3%, whereas the porosity was less by 19.3%. Compared with grey-mud paddy fields, the activity of catalase in yellow-mud paddy fields was higher by 20.4%, but the activity of urease was less by 40.4%.This indicated that compared with high-producing fields, yellow-mud paddy fields belonged to low-fertility and short-acting soils with insufficient soil organic matter, total nutrients and available nutrients, low contents of macro/micro elements, CEC, etc.The above 19 soil characteristics with significant differences between the two soils constituted the IDS.Six principal components, with cumulative contribution of 76.22%, were selected from IDS reflecting the synthetic fertility properties of yellow-mud paddy fields.The final established MDS composed of five factors, including CEC, total potassium, available phosphorus, available boron and porosity for fertility quality assessment according to the expert experience and correlation analysis.The calculated SFQI from MDS of yellow-mud paddy fields was equivalent to 69.5% of that of grey-mud paddy fields. Correlation analysis on SFQI for IDS and MDS indicated that MDS could replace IDS and correctly used to evaluate soil fertility quality of yellow-mud paddy fields.Moreover, MDS could also be used in studies on how to improve soil fertility.