Case Study Site 12: Suining, Sichuan, China
Responsible partner: 20 - SFI
1. Geographical description
Calcareous Purplish Soil field station was established in 1982, in Suining city of Sichuan province, which is in the middle of hilly Sichuan basin (Figure 20). This region belongs to a sub-tropical humid monsoon climate, with a mean annual temperature of 18.5 ˚C and rainfall of 927 mm. Agricultural lands comprise 0.15 million hectares, with Calcareous Purplish Soil land accounting for 62%. The main agricultural crops are grain, cotton, oil, fruit, and mulberry. Rice-wheat and rice-rape rotation are the main farming systems in this area. Irrigation water is derived from both the Peijiang River and from rainfall sources. Population density is 813 people per km2.
Figure 20. Case study site location near Suining, Sichuan.
2. Main farming systems and typical agricultural management activities in the study area
The main farming systems are rice-wheat rotation and rice in this study area (Figure 21). Overuse and under-application of fertilizer occurred within this cropping system. Farmers prefer to use more N fertilizer which has led to an in-balance in N, P and K and the N application timing did not match the crop nutrient demand. Nutrients from the natural environment and the characteristics of nutrient dynamic during the rice-wheat rotation period were not considered when farmers determined the fertilizer application rate. The strategy included nutrient management from the whole rotation system perspective, the integrated use of nutrients from various sources (chemical fertilizers, organic fertilizers and nutrients from the environment), using different management technologies according to the characteristics of different nutrient resources, and integrating nutrient management with other cropping system technologies, such as water saving and high yield cultivation.
Figure 21. Main agricultural crops in Sichuan.
3. Characteristic soils and soil quality monitoring practice
The soil is a calcareous purple paddy soil, with the main mineral consisting of hydromica, kaolinite and quartz. When the field experiment station was established in 1982, the top 20 cm of soil contained 15.9 g kg-1 soil organic matter (SOC), 1.09 g kg-1 total N (TN), 3.9 mg kg-1 Olsen-P (OP) and 130 mg kg-1 exchangeable K (EK) with a pH value (soil-to-water ratio 1:1) of 8.6 at the start of the experiment. Soil quality monitoring practices include: i) collection crop yield data from 1982 to 2013, ii) monitoring soil total N, P, K, SOC, Olsen-P, EK and pH in 1986, 1990,1994, 1998, 2006 and 2012.
4. Ongoing research and innovation actions on soil improvement and monitoring
Ongoing research and innovation actions on soil focuses on: i) crop yield evolution under long-term fertilization, ii) effect of long-term located fertilization on soil potassium balance and form transformation in purple soil under paddy rice and wheat, and iii) soil microbe, organic carbon fractions and their recycles.
5. Stakeholders to be included in the research
The main stakeholders for the Sichuan study site will be local farmers and companies, local agricultural departments and local advisory services.
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