周年磷肥旱季集中底施对玉-稻轮作磷肥效应的影响

春玉米-晚稻水旱轮作是近年来南方稻区种植制度变化下出现的新型两熟制模式。明确两季作物间磷肥的合理分配对玉-稻轮作作物产量与磷素利用效率的影响,对玉-稻轮作养分高效与高产协同实现,及丰富对水旱轮作前后季作物养分利用关系的认识具有理论意义。采用春玉米-水稻周年轮作田间试验,根据晚稻季磷肥前移至玉米季做底肥施用的比例及周年施磷量,设置7个磷肥施用处理,分别为两季作物均不施磷(P_0)、两季作物均按常规方法施磷(P_1)、1/3晚稻季磷肥前移(P_2)、2/3晚稻季磷肥前移(P_3)、全部晚稻季磷肥前移(P_4)、全部晚稻季磷肥前移且周年总施磷量减少15%(P_5)、全部晚稻季磷肥前移且周年总施磷量减少30%(P_6),分析了不同施磷处理作物产量、磷素吸收量及磷素利用效率的变化。与P_1相比,P_3与P_4处理显著提高了晚稻花后干物质的分配比例及晚稻产量,且其周年产量分别提高了4.87%和6.74%;P_5处理晚稻产量与P_1处理差异不显著,但P_6显著降低了晚稻产量。晚稻季磷肥前移施用明显促进了玉米及晚稻对磷素的吸收,显著降低了磷素的表观盈余量。与P_1处理相比,P_2、P_3、P_4处理两季作物周年土壤磷素依存率分别减少了11.63%、26.47%与22.08%。从磷肥利用效率看,P_4处理的磷肥周年累积回收效率、农学利用效率、偏生产力及磷肥产量贡献率均显著高于P_1处理,分别提高了102.46%、194.83%、6.73%与176.16%。与P_1处理相比,P_5处理周年磷肥产量贡献率及农学利用效率差异不显著,但分别提高了其磷肥回收效率与偏生产力32.56%和58.05%。玉米季施用的磷肥对晚稻有明显的后效作用,且比晚稻季施用磷肥具有更高的磷肥利用效率。所以在春玉米免耕复种晚稻时,可将晚稻季的磷肥全部前移至玉米季施用,并可减少15%周年施磷量。

INFLUENCE ON P USE EFFICIENCY BY APPLICATION OF ANNUAL P AS#br# BASAL FERTILIZER IN MAIZE SEASON UNDER MAIZE RICE ROTATION

The “spring maize & late rice” rotation is a new planting type in southern China recently. The phosphorus(P) fertilizer allocation in the two season crops(maize and rice) is important for understanding how P fertilizer efficiencies affect on crops yields. An annual maize rice field experiment was conducted in Wuxue County, Hubei province between March and October 2015. According to the P fertilizer amount used in the two crops, seven treatments were applied in the experiment, which includes no P application in both crop seasons(P0), conventional P application in both crop seasons(P1), 1/3 P for late rice was forward applied as basal fertilizer in maize season(P2), 2/3 P for late rice was forward applied as basal fertilizer in maize season(P3), all P for late rice was forward applied as basal fertilizer in maize season(P4), all P for late rice was forwarded and the total annual P was decreased by 15%(P5) and all P for late rice was forwarded and the total annual P was decreased by 30%(P6), respectively. We analyzed the crop yields, phosphorus uptake and phosphorus use efficiency in different treatments. Compared with the conventional P application(P1), the P3 and P4 treatments significantly increased the rice yield and the allocation of rive dry matter, maize, and rice yields increased by 4.87% and 6.74% respectively. There was no significant difference in rice yields between P5 and P1, but the yield of late rice was significantly decreased when the annual total P application decreased by 30%(P6). The forward application in maize season of P fertilizer for the late rice season significantly promoted the uptake of P by maize and late rice, and significantly reduced the apparent surplus of soil P. The soil phosphate dependent rate of two crops decreased significantly under P2, P3, and P4 treatments, in comparison with P1 treatment, by 11.63%, 26.47%, and 22.08%, respectively. From the perspective of P use efficiency, the P fertilizer cumulative recovery efficiency, agronomic efficiency, partial factor productivity and fertilization contribution rate of P4 treatment were significantly higher than those of P1, which was increased by 102.46%, 194.83%, 6.73% and 176.16%. Compared with P1 treatment, the treatment of P5 had no significant effect on the annual P fertilizer contribution rate and agronomic efficiency but increased the P recovery efficiency and partial factor productivity by 32.56% and 58.05%. The study proved that P application in maize season had significant residual effects in late rice season, and it had higher P use efficiency than that the P application in the rice season. All P fertilizer for late rice could be moved to maize season, and even the total P application amount was reduced 15%.