Current situation and spatial-temporal distribution of soil available sulfur in Anhui Province

Objectives Soil available sulfur (S) is the main source for plant S nutrition. The regional soil sulfur efficiency of the arable land in Anhui Province was systematically studied so as to provide reference for scientific application of S fertilizers and the balanced fertilization.

Methods 345 thousands of soil samples were collected from 0–20 cm soil layers around Anhui Province. The covered soil types included fluvo-aquic soils, lime concretion black soils, yellow-cinnamon soils and paddy soils etc. The spatial-temporal distribution of soil available S content was analyzed using large sample data and Kriging interpolation on ArcGIS platform.

Results 1) Soil available S was in the range of 0.10–101.90 mg/kg with a mean of 24.99 mg/kg and a median of 21.00 mg/kg. 2) Soil available S was generally insufficient, 53.1% of the total samples were deficient in soil available S (< 22 mg/kg). 3) The situation of soil available S deficiency increased from east to west and from middle to south and north. 4) The soil available S deficiency became worse in brown soils, yellow fluvo-aquic soils, skeleton soils, red soils, yellow soils, purple soils and lime concretion black soils. Compared with 20 years ago, soil available S deficiency was alleviated along the Changjiang River Plain, Jianghuai Hill and West Anhui, but became more serious in south Anhui. At present, the frequency and risk of soil available S deficiency increased in brown soils, lime concretion black soils and yellow-brown soils, but decreased in yellow fluvo-aquic soils, yellow-cinnamon soils and grey fluvo-aquic soils.

Conclusions The arable land area with soil available S deficiency (< 16 mg/kg) and relatively deficiency (16–22 mg/kg) was about 311.19 × 10⁴ hm², accounting for 53.1% of the total cultivated land in Anhui Province. Considering the high ratio (39.67%–56.89%) of soil available S deficiency (< 16 mg/kg) in the 9 soil types including brown soils, lime concretion black soils, yellow fluvo-aquic soils and red soils etc., S fertilizers should be applied to decrease the risk of crop S deficiency.