Investigation On Distribution Of Phosphate Between Crops In Maize-rice System

Maize- rice cropping pattern is a new developed pattern in the middle reaches of the Yangtze River during recent years. However, the nutrient distribution between the two crops and reasonable anniversary fertilization management are still unclear. In 2014, yield and dynamics of nitrogen(N), phosphorus(P) and potassium(K) during the whole growth period of the two crops under three fertilization patterns were concerned in the system in Wuxue, Hubei Province. Based on the results obtained in 2014, an experiment of seven different phosphorus fertilization treatments in this system was conducted in 2015, mainly focusing on the changes of soil available nutrient, anniversary nutrient budget balance of the system and the effect of phosphorus of rice season applied forward to the maize season on production and nutrient uptake and utilization. And an efficient and practical phosphate fertilization strategy to boost the yield, promote nutrient absorption and then improve benefit was supposed to propose via this study. The main results are as follows:(1)In 2014, three treatments were set in the experiment, including normal fertilization during the two seasons(MR), normal fertilization at maize season but no fertilization at rice season(MR0) and no fertilization during the two seasons(M0R0). The results revealed that compared with NO3-, NH4+ and available K in soil before maize season, they decreased significantly sampled after maize harvest and rice harvest at all three treatments, while soil available P raised at MR treatment, decreased slightly at MR0. In the aspect of N、P、K nutrient budget balance, nitrogen after maize season at MR and MR0 presented lack for the rice growth, K was just enough, while 2/5 of P fertilized at maize season remained in soil. In conclusion, based on the fertilization patterns in our study, P at maize season will remain on soil, while N and K will not. However, the growth and yield at MR0 and M0R0 treatments has no significant difference, it means that the remaining P has no effect on the growth of rice in lack of N and K.( 2) Seven treatments were conducted in 2015, including M0R0, normal fertiliazation during two seasons(M1R1), 1/3 of P in rice season fertiliazed forward to maize season(M2R2), 2/3 of P in rice season fertilized forward to maize season(M3R3), all P in rice season fertiliazed forward to maize season(M4R0), all P in rice season fertiliazed forward to maize season and the anniversary P decreased 15%(M3R0), all P in rice season fertiliazed forward to maize season and the anniversary P decreased 30%(M2R0). The results showed that:(1) compared with M1R1 treatment, the treatments of P fertilized forward but the anniversary P kept the same(M2R2, M3R3, M4R0) obtained similar biomass of maize and rice, but the biomass of rice increased remarkablely at M3R3. Besides, the biomass of maize has no significant change but the biomass of rice decreased at M3R0 and M2R0 treatments.(2) rice at M2R2, M3R3 and M4R0 presented higher yield than M1R1, and the yield of maize and the total yield of the two seasons showed higher at M4R0. M3R0 had no significant difference with M1R1, while M2R0 obtained lower yield of rice, but no difference on maize and aniversary yield.(3) compared with M1R1, M2R2, M3R3 and M4R0 increased the P uptake of maize and rice, M3R0 and M2R0 has the similar effect on P uptake of maize but no increase on rice.(4) compared with M1R1, M2R2,M3R3 and M4R0 presented no effect on available P on rice but the M3R0 and M2R0 decreased it, and all treatments of P fertilized forward promoted the anniversary P budget balance in the system.(5)M2R2、M3R3、M4R0 significantly elevated the agronomic use efficiency of phosphorus and increase the contribution rate of production increase which induced by phosphate fertilizer by1.9-3 and 2.4-4.1 times compared with M1R1; M3R0 has no significant influence on the agronomic use efficiency of phosphorus, however, M3R0 significantly elevated the contribution rate of production increase which induced by phosphate fertilizer.Based on the above results, we find that in order to achieve higher crop yields and improve the utilization efficiency of Phosphate fertilizer,we can take 2/3 or all of phosphate fertilizer in season rice forward as base fertilizer of maize season;Thus, Annual Phosphate fertilizer application rate can be reduced by 15% when annual yield has no significant change.