40 Years’ Change Characteristics of Soil Basic Properties in the Main Planting Area of Winter Oilseed Rape

The objective of this study was to investigate the changes in basic physical and chemical properties of soils in the main winter oilseed rape producing areas in the Yangtze River Basin over the past 40 years, and to clarify the characteristics of changes in comprehensive soil fertility of arable land in winter rape growing areas, in order to provide a scientific basis for conservation and soil fertility improvement in low and middle yielding fields in the Yangtze River Basin.

By collecting and organizing the data from published literatures, master’s and doctoral dissertations at home and abroad in the past 40 years, the temporal variation characteristics of basic soil properties in winter oilseed rape growing areas in the Yangtze River Basin were analyzed. Then the variation characteristics of integrated soil fertility (IFI) and its correlation with basic soil physical and chemical properties were evaluated.

The average values of soil organic matter, total nitrogen, available phosphorus and potassium, and pH in the main winter oilseed rape producing areas of the Yangtze River Basin were 18.54 g·kg^-1, 1.16 mg·kg^-1, 8.60 mg·kg^-1, 42.90 mg·kg^-1, and 6.26 during the period of 1981-1990, respectively, but enhanced to 25.60 g·kg^-1, 1.41 mg·kg^-1, 18.66 mg·kg^-1, 108.98 mg·kg^-1, and 6.31 by 2016-2020, respectively. Clearly, the soil basic physical and chemical properties have been improved extensively in planting area of winter oilseed rape in the Yangtze River Basin. The average annual increase rate was 1.2% in soil organic matter and 0.7% in soil total nitrogen. Soil available phosphorus and available potassium were enhanced by 3.0% and 4.0% per year, respectively. Soil pH remained stable in the past 40 years, with the mean range of 6.21-6.45 among different periods. Based on the improved Nemerow index method, soil IFI value was also found enhanced in the past four decades. Compared with the mean IFI in the period of 1981-2000, the value was significantly increased by 14.8%-30.4% during the period of 2001-2020. The IFI was positively correlated with soil organic matter, pH, total nitrogen, available phosphorus and available potassium. Path analysis showed that soil available potassium was the most important index affecting IFI, followed by soil total nitrogen and available phosphorus.

The basic physical and chemical properties and comprehensive fertility of the soil was significantly improved in the past 40 years in the planting area of winter oilseed rape. Developing the planting area of oilseed rape would be benefit for soil fertility and productivity improvement in the Yangtze River Basin, especially for the farmland with low yield productivity.