Abstract:
Objectives This study investigated the effects of long-term application of varying doses of sewage sludge compost (SW, comply with quality standard) on crop yield and topsoil organic carbon storage (SOCS) and total nutrient contents in a winter wheat-summer maize rotation system in North China. The result will provide reference for the efficient utilization of sewage sludge compost in agriculture.
Methods A field experiment was conducted from 2008 to 2020 in Changping District of Beijing. The treatments included 100% urea (N), 50%SW + 50% urea (0.5SW+0.5N), 100%SW + 50% urea (SW+0.5N), 200%SW + 50%urea (2SW+0.5N), and 400%SW + 50%urea (4SW+0.5N). Wheat and maize yield, as well as SOCS, total nitrogen (TN), total phosphorus (TP), and total potassium (TK) contents in 0–20 cm soil layer were measured each year. The soil carbon sequestration efficiency was also calculated.
Results With the increasing of sewage sludge compost input, wheat and maize grain and straw yields increased. The multi-year average yields of wheat and maize grains and straw in 0.5SW+0.5N treatment were not significantly different from that in N treatment, while those in SW+0.5N, 2SW+0.5N, and 4SW+0.5N were significantly increased, with the increment in wheat grain yields by 6.97%, 14.88%, and 17.94%, and in maize grain yields by 8.43%, 11.77%, and 15.38%, respectively. The SOCS, TN, TP, and TK kept enhanced with the increase of sewage sludge compost input amounts (P<0.05). The multi-year average TN in treatment N, 0.5SW+0.5N, SW+0.5N, 2SW+0.5N, and 4SW+0.5N were 1.07, 1.26, 1.56, 1.93, and 2.73 g/kg; the multi-year average TP were 1.19, 1.67, 2.37, 3.27, 4.11 g/kg; and the multi-year average TK were 18.60, 19.06, 19.85, 20.07, 21.19 g/kg, respectively.
Conclusions Replacing 50% of urea N with sewage sludge compost will not impact the wheat and maize yield, but increase soil fertility significantly. Under half of conventional urea N input rate, increasing the application rate of sewage sludge compost could significantly elevate the wheat and maize grain yields, especially when the application rate is 4 times of the urea N input, the grain yield will be increased by 15%−18%, and the soil organic carbon and nutrient storage increased greatly, which boosts the sustainability of grain yields and the carbon sink effect of soil.