| Adequate nutrient supply is the material foundation for crop yield,and the application of fertilizer ensures the development of agricultural production in China.Rice is an important staple food crop in China,and the Yangtze River Basin is the main producing area of rice.It is generally planted under the annual multiple cropping mode of oilseed rape-rice rotation(OR)or wheat-rice rotation(WR).Excessive fertilization is a common problem in rice production in China,and the differences of rice response to fertilization among different rotation systems have been ignored for a long time,and lacking targeted and precise fertilization strategies.In order to clarify the differences of rice yield,nutrient utilization and their response to fertilization between oilseed rape-rice and wheat-rice rotation,a two-season field experiment was carried out in 2021 and 2022 by using a field positioning experiment established in Shayang,Hubei Province.The effects of three fertilization rates no fertilization(CK),optimized fertilization(OPT)and conventional fertilization(HIT)on rice yield,growth dynamics,nutrient uptake,utilization of nitrogen,phosphorus and potassium and soil nutrient balance in two rotation systems of oilseed rape-rice and wheat-rice were investigated in order to provide a basis for scientific fertilization of rice in the oil-wheat interlaced zone.The main research results are as follows:(1)The yield of rice in oilseed rape-rice rotation was higher than that in wheat-rice rotation,and the difference of rice yield under different fertilization treatments was different.In 2021 and 2022,the average yield of rice in oilseed rape-rice rotation under three fertilization rates was 10.5% and 12.5% higher than that of rice in wheat-rice rotation,respectively.Under the CK treatment,the average yield of rice in oilseed rape-rice rotation for 2 years was significantly 29.2% higher than that of rice in wheat-rice rotation;Under the OPT treatment,the average yield of rice in oilseed rape-rice rotation for 2 years was 4.4% higher than that of rice in wheat-rice rotation;Under the HIT treatment,the average yield of rice in oilseed rape-rice rotation for 2 years was 1.0% higher than that of rice in wheat-rice rotation.(2)Fertilization increased rice yield,and the effect of fertilization on yield increase was different in different rotations.The results of the two-year experiment indicated that compared with the CK treatment,OPT and HIT treatments increased rice yield by an average of 166.3% and 161.9% in the two rotation modes,respectively.There was no significant difference in rice yield between OPT and HIT treatments.In the 2021 and2022 rice seasons,compared with the CK treatment in oilseed rape-rice rotation,the OPT treatment increased rice yield by 93.7% and 180.4%,respectively;the HIT treatment increased rice yield by 91.6% and 167.0%,respectively;In wheat-rice rotation,the OPT treatment increased rice yield by 131.0% and 259.8%,respectively;the HIT treatment increased rice yield by 139.5% and 249.8%,respectively.(3)Fertilization promoted rice growth,and there were differences in rice growth between different rotations.In the 2022 rice season experiment,fertilization significantly increased the number of tillers,leaf area index,and biomass of rice.Non fertilization delayed the growth and development of rice.Compared with OPT and HIT treatments,the CK treatment delayed the rapid growth of biomass by an average of 20.3 days and20.1 days in both rotations,respectively.Under the same fertilization treatment,there were differences in rice growth between different rotations,and there were significant differences under the CK treatment.Compared with wheat-rice rotation,the tiller number,leaf area index and biomass in oilseed rape-rice rotation increased by an average of 23.2%to 28.8%,15.9% to 75.3% and 19.5% to 33.7%.(4)The accumulation of nitrogen,phosphorus,and potassium nutrients in rice increased with the increase of fertilizer application,and the distribution of nutrients in rice was affected by fertilizer application.There were differences in the accumulation of nutrients in rice in different rotations.During the entire growth period of rice,there were significant differences in nutrient accumulation among different fertilization treatments in both rotations.Compared with the CK treatment,the average accumulation of nitrogen,phosphorus,and potassium nutrients in the OPT treatment increased by 155.0%～420.5%,135.5%～1375.5%,and 104.4%～509.9%,respectively;The average accumulation of nitrogen,phosphorus,and potassium nutrients in the HIT treatment increased by215.3%～464.4%,278.1%～1813.4%,and 137.9%～625.6%,respectively.Fertilization can change the distribution of nitrogen,phosphorus,and potassium nutrients in various parts of rice.In both rotations,the proportion of nutrient accumulation in rice stems and leaves increased with the increase of fertilization amount,while the proportion of nutrient accumulation in panicles decreased.Under the same fertilization treatment,compared with wheat-rice rotation,the accumulation of nitrogen,phosphorus,and potassium nutrients in rice under oilseed rape-rice rotation increased to varying degrees.There were significant differences under the CK treatment,and the accumulation of nitrogen,phosphorus,and potassium nutrients in rice in oilseed rape-rice rotation was24.8%～42.4%,31.7%～73.8%,and 12.5%～50.4% higher than that in wheat-rice rotation,respectively,and there were significant differences in rice nutrient accumulation between different rotations from rice elongate stage to maturity stage.(5)Moderate fertilization can improve the fertilizer utilization efficiency of rice and reduce the surplus of nitrogen,phosphorus,and potassium nutrients in the soil.There were differences in the balance of nitrogen,phosphorus,and potassium nutrients in different rotation soils.Compared with the HIT treatment,in the rotation of oilseed rape-rice and wheat-rice,the fertilizer recycling efficiency,agronomic utilization efficiency,partial productivity,and physiological utilization efficiency of the OPT treatment increased by 36.6% and 37.5%,95.5% and 88.6%,90.1% and 86.4%,42.5%and 38.5%,respectively.Compared with the HIT treatment,the OPT treatment reduced nitrogen surplus by 76.7% and 72.2%,and phosphorus surplus by 74.9% and 66.8% in the oilseed rape-rice and wheat-rice rotation systems,respectively.Rotation has a significant impact on soil nutrient balance.In the OPT treatment,the surplus of soil nitrogen and phosphorus nutrients in oilseed rape-rice rotation was 25.3% and 30.1% lower than that in wheat-rice rotation,respectively;In the HIT treatment,the surplus of soil nitrogen and phosphorus nutrients in oilseed rape-rice rotation was 11.0% and 7.5% lower than that in wheat-rice rotation,respectively.In summary,the combination of appropriate fertilization rates and reasonable rotation mode is beneficial for the high yield and efficient production of rice.In the oil-wheat interlaced zone of the Yangtze River Basin,paddy-upland rotation mode of annual multiple cropping of oilseed rape and rice selectively can promote grain and oil abundance and improve the annual nutrient utilization efficiency of the paddy-upland crop rotation. |
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