| The Guanzhong Plain has always been one of the main grain producing areas in China.The winter wheat-summer maize double cropping rotation per year is a common farming method in the local area.Phosphorus,as an essential nutrient element for plant growth and development,plays an important role in the entire development process of crops.Therefore,large quantities of phosphorus fertilizers are used to increase crop yields in production.However,the investigations in recent years have shown that with the usage of fertilizers increasing,crop yields have not increased significantly,due to the fertilizer utilization rate and soil quality have declined.Taking the Guanzhong area as an example,excessive application of phosphorus is quite common,resulting in a large surplus of phosphorus in the soil,which not only wastes phosphate fertilizer resources,reduces actual income benefits,but may also cause a series of environmental problems.In this study,a field experiment of winter wheat-summer maize rotation with phosphorus application in wheat season and no phosphorus application in maize season was conducted in Caoxinzhuang Experimental Farm of Northwest A&F University of Yangling.To clarify the feasibility of phosphorus application in wheat season to maintain crop growth and nutrient utilization in the winter wheat-summer maize rotation system,and determine the rational usage of phosphorus fertilizer to provide technical guidance for the efficient application of phosphorus fertilizer.The effects of different phosphorus fertilizer application on the accumulation and distribution of dry matter,nitrogen and phosphorus,and transportation regulation of the organs of winter wheat and summer maize,as well as the utilization of phosphorus fertilizer were analyzed.The main research results were showed as follows:1.The application of phosphate fertilizer in the wheat season significantly increased the dry matter accumulation of the wheat-maize rotation system.Compared with non-phosphorus treatment,the application of phosphate fertilizer in winter wheat season increased the dry matter accumulation of winter wheat in the current season and summer maize in the next season.The dry matter accumulation of winter wheat was higher than that of summer maize.Compared with 150 kg/ha phosphorus application,the dry matter accumulation of winter wheat and summer maize not only did not increased significantly but even had a certain downward trend under the condition of 225 kg/ha and 300 kg/ha.The annual total dry matter accumulation of the rotation system conform to a parabolic trend.The equation showed reached the maximum value of annual total dry matter accumulation when phosphorus application was 187 kg/ha2.Phosphorus application in wheat season significantly increased the dry matter transfer amount and transfer rate of winter wheat and summer maize.The dry matter distribution of each organ of the winter wheat during the flowering period of the two years was as follows: stem(stem + sheath)>ear(cob + glume shell)> leaf,which was grain >stem > glume shell > leaf in the harvest period.Compared with non-phosphorus treatment,the dry matter accumulation of each organ of winter wheat increased significantly.And the total dry matter transfer amount(rate)of winter wheat plants also increased significantly.During the silking period of summer maize,the dry matter accumulation of each organ was stem > leaves > bracts successively,which was grains > stems > leaves > cobs > bracts in harvest period.Compared with non-phosphorus treatment,the dry matter accumulation of each organ of summer maize increased.The application of phosphorus in winter wheat season showed a certain aftereffect,which promoted the transfer amount(rate)of dry matter for the stems and leaves of summer maize.The total dry matter transfer amount(rate)of winter wheat plant was the best at 150 kg/ha phosphorus fertilizer.The dry matter transfer amount(rate)of the stems and leaves of summer maize was better at 75 kg/ha and150 kg/ha phosphorus fertilizer.3.Phosphorus application in wheat season significantly increased the phosphorus accumulation of winter wheat and summer maize at the flowering and harvest period.Compared with non-phosphorus treatment,the distribution amount of phosphorus in each organ increased significantly.Phosphorus accumulation in each organ of winter wheat was stems > spikes > leaves successively in the flowering period.The phosphorus distribution amount of grain was the highest in the harvest period,followed by stems.The phosphorus distribution amount of leaves and cobs had no obvious regularity.Compared with non-phosphorus treatment,phosphorus application significantly increased the phosphorus accumulation in each organ of wheat,and the distribution of each organ was the highest at225 kg/ha phosphorus fertilizer.The phosphorus accumulation in each organ of summer maize was shown as stem > leaf > bract successively in the flowering period of 2019 and2020.During the harvest,the phosphorus accumulation in each organ was shown as grain > leaf > stem > shaft > bract in 2019.The phosphorus distribution amount of grain was the highest,followed by leaf in 2020.There was no obvious pattern in other organs.The application of phosphorus fertilizer in the wheat season significant increased the phosphorus accumulation in each organ during the silking and harvesting period of summer maize.4.Phosphorus application increased the transfer rate and contribution rate of phosphorus in each organ of winter wheat and summer maize,but high phosphorus conditions such as 225 kg/ha and 300 kg/ha had an inhibitory effect on the transfer rate of summer maize stems and leaves.The total phosphorus transfer rate of winter wheat plants increased with the increase of phosphorus application,which was the largest at 300 kg/ha.The contribution rate of phosphorus was the largest at 225 kg/ha,and significantly decreased over 225 kg/ha.There was no significant difference in the total phosphorus transfer rate and contribution rate of summer maize between 0 ～ 150 kg/ha of phosphorus fertilizer,which was significantly decreased over 150 kg/ha.5.With the increase of phosphorus application,the wheat season fertilizer utilization rate and agronomic efficiency utilization rate of the winter wheat-summer maize rotation system decreased.The phosphorus utilization rate of winter wheat and the annual cumulative phosphorus utilization rate of wheat-maize was the highest(15.07% and 21.8%)at 75 kg/ha phosphorus fertilizer.As the amount of phosphorus increased,the utilization rate of phosphorus fertilizer decreased.The physiological efficiency of winter wheat season and wheat-maize anniversary both showed the maximum at 150 kg/ha. |
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