Abstract: To examine the effects of plastic film mulching and organic manure application on C, N, and P stoichiometry of soil and crop, we collected soil and corn tissues (root, stem, leaf, and seed) in 2015 from a longterm experiment at Shenyang Agricultural University, which was initiated in 1987. We measured C, N and P concentrations in soil and crop tissues. Results showed that the main and interactive effects of long-term film mulching and manure application on soil pH were statistically significant. Film mulching did not affect soil C, N, P, available N and P concentrations, and soil C∶N∶P ratios (P>0.05). Manure application significantly increased soil total C, N, P, available N, and available P concentrations (P<0.01), and significantly decreased soil C/P and N/P ratios (P<0.01). Film mulching did not affect the stoichiometry of C, N, and P in all plant tissues except for leaf N and seed P concentration and C/P ratio. Organic fertilizer application significantly increased N concentration and decreased C/N ratios in all tissues (P<0.05). Manure application increased root and seed P concentrations (P<0.05) and decreased seed C/P ratio (P<0.001). In conclusion, soil and crop C, N, and P stoichiometry could be affected by long-term organic fertilizer application but not by plastic film mulching.

Key words: leaf area index., semi-arid region of Loess Plateau, grain yield, withinrowintercropping, planting density