Effects of long-term fertilization on photosynthetic characteristics and yield of spring maize in upland red soil

To study the effects of different fertilization management on net photosynthetic rate of leaf(Pn),leaf area index(LAI) and yield of spring maize(Zea Mays L.),a 19-year long-term fertilization experiment has been conducted in Red Soil Experimental Station Qiyang,China.The fertilization treatments include no fertilizer(CK),application of inorganic fertilizers(NPK),application of organic fertilizer(OM) and combined application of organic and inorganic fertilizers(NPKM).The results indicated that,in comparison with NPK treatment,application of OM fertilization could increase Pn at main development stages of spring maize.And application of OM fertilization also increased LAI,aboveground biomass,grains per spike,100-seed weight and harvest index of spring maize,thus increased yield by 333.23%.In comparison with OM treatment,application of NPKM fertilization only improved Pn at seedling stage of spring maize,but did not increased LAI,aboveground biomass and yield significantly.Analysis with soil nutrient status and average yield from 1991 to 2009,long-term combined application of organic and inorganic fertilizers is a better fertilization method in this area.