Response of rice yield to different levels of long-term fertilization regimes and the environment

This study was based on a long-term fertilization experiment on rice-rice rotation started in 1982 at the HengYang Red Soil Experiment Station of Chinese Academy of Agricultural Sciences. Six fertilization treatments of the experiment were chosen — chemical nitrogen (N), phosphorus (P) and potassium (K) fertilizer (NPK), cattle manure (M), NPK plus M (NPKM), NP plus M (NPM), NK plus M (NKM) and PK plus M (PKM) in this study. The effects of fertilization, environment and their interaction on rice yield stability were determined according to inter-annual variability and coefficient of variation (CV) of rice yield, sustainable yield index (SYI), contribution of fertilizer to rice productivity, as well as the additive main effects and multiplicative interaction (AMMI) model. Results showed that among the various treatments, NPKM treatment had the highest grain yield. Rice yield increased with increasing N fertilizer. The yield-increasing effect of combined application of chemical P and K fertilizers was better than that of sole application of P or K fertilizer at the same N application rate. Chemical K fertilizer presented better yield-increasing effect than chemical P fertilizer. Under long-term application, organic fertilizer was more favored rice yield increase than chemical fertilizer. There was no significant difference in early rice yield between M and NPK treatments under the same nutrient input. However, yield of late rice under M treatment was significantly higher than that under NPK treatment. For all the treatments, the CV of rice yield decreased with time. However, the application of M plus chemical fertilizers had smaller yield CV than the application of chemical fertilizers alone. For all the treatments, the CV of late rice yield was higher than that of early rice yield. However, the SYI of late rice yield was lower than that of early rice. Also for all the treatments, SYI (0.51) was highest for NPKM treatment (0.51). SYI for M and NPK treatments were 0.44 and 0.42, respectively. The order of contribution rate of fertilizers to rice yield was: organic fertilizer > chemical N > chemical P > chemical K. The results of AMMI model showed that different fertilizer treatments had different response to the environment for different experimental years. Thus based on the results, the use of chemical fertilizers in combination with organic fertilizers (NPKM) was the optimal fertilization regimemode of maintaining high crop productivity and yield stability under of double cropping rice in the study area.