| Phosphorus is one of the necessary nutrients for rice growth and development.Based on the basic national conditions of the shortage of water resource s per capita and the decreasing phosphorus resources in China,the effects of reducing the application of different levels of phosphorus fertilizer under different irrigation modes on the growth and development of rice,yield,water and phosphorus utilization efficiency,plant phosphorus absorption and accumulation,soil phosphorus content and soil phosphorus surplus were carried out in Heilongjiang Province.A reasonable water and fertilizer mode was obtained by comprehensive comparison.On the basis of maintaining the stable yield and even increasing yield of rice,it is of great significance to improve the utilization rate of phosphorus fertilizer,reduce the residual phosphorus fertilizer in the soil,and reduce the risk of environmental pollution.At the same time,it also provides reference and basis for the application of chemical fertilizer in black soil rice.In 2020 and 2021,a field experiment was conducted at the National Irrigation Experimental Station of Qing’an County,Heilongjiang Province.Two different irrigation modes(F:conventional flooding irrigation,C:controlled irrigation)and five different phosphorus application rates(P0:0kg/hm~2(no fertilization),P1:18 kg/hm~2(phosphorus reduction 60%),P2:27 kg/hm~2(phosphorus reduction 40%),P3:36 kg/hm~2(phosphorus reduction 20%),P4:45 kg/hm~2(conventional fertilization)were set up,with 10 treatments.The effects of phosphorus fertilizer reduction on plant height,tiller number,yield,dry matter accumulation and phosphorus accumulation in aboveground organs,water and phosphorus use efficiency,soil available phosphorus,total phosphorus content and soil phosphorus surplus under different irrigation modes were studied.The main research results of this experiment are as follows:(1)Reducing phosphorus fertilizer under different irrigation modes is beneficial to the growth and development of rice,reducing ineffective tillering,promoting panicle rate and increasing yield.Under the two irrigation modes,the P3 treatment with reduced phosphorus fertilizer can improve rice yield compared with conventional fertilization P4 treatment.In 2020,the rice yield of P3treatment with controlled irrigation mode increased by 191.21 kg/hm~2 compared with P4 treatment,and the rice yield of P3 treatment with conventional flooding irrigation mode increased by 286.71kg/hm~2 compared with P4 treatment.In 2021,the rice yield of P3 treatment increased by 162.4kg/hm~2 compared with that of P4 treatment,and the rice yield of P3 treatment increased by 95.2kg/hm~2 compared with that of P4 treatment.Compared with conventional flooding irrigation,controlled irrigation improves water use efficiency and reduces water consumption.(2)Reducing phosphorus fertilizer under two irrigation modes is beneficial to the formation of dry matter in various organs of rice aboveground.Under the control irrigation mode and conventional flooding irrigation mode,the dry matter weight of stems and panicles of P3 treatment with reduced P fertilizer was the largest,which was significantly higher t han that of P4 treatment(P<0.05).Under the two irrigation modes,the dry matter weight of leaves was the highest under the conventional fertilization P4.The dry matter weight of stem and spike in control irrigation mode was significantly higher than that in conventional flooding irrigation mode.Leaf dry matter weight was significantly lower than that of conventional flooding irrigation(P<0.05).The order of phosphorus accumulation in aboveground organs was grain,stem sheath and leaf.(3)Under the two irrigation modes,the phosphorus accumulation in stem sheath and grain first increased and then decreased with the increase of fertilizer application rate.The phosphorus accumulation in stems,sheaths and grains of P3 treatment with P fertilizer reductio n was significantly higher than that of P4 treatment with conventional fertilization(P<0.05).Leaf phosphorus accumulation of conventional fertilization treatment was significantly higher than that of phosphorus reduction treatment(P<0.05).The phosphorus accumulation of stem sheath and grain in control irrigation mode was significantly higher than that in conventional flooding irrigation mode(P<0.05).There was no significant difference in leaf phosphorus accumulation between the two irrigation modes.The absorption and utilization rate of phosphorus fertilizer increased first and then decreased with the increase of fertilizer application rate.In 2020,the phosphorus absorption and utilization rate and partial productivity of conventional flooding irrigation mode were higher than those of control irrigation mode,while in 2021,the phosphorus absorption and utilization rate of control irrigation mode was higher than that of conventional flooding irrigation mode.The agronomic utilization rate of phosphor us fertilizer in controlled irrigation mode was higher than that in conventional flooding irrigation mode,and the utilization rate of phosphorus fertilizer in 2021 was significantly higher than that in 2020.(4)Under the two irrigation modes,reducing phosphorus fertilizer was beneficial to the increase of soil surface available phosphorus content,and the relationship between soil available phosphorus content in each soil layer was 0～20 cm,20～40 cm and 40～60 cm.Reducing the application of phosphorus fertilizer for two consecutive years is beneficial to increase the soil available phosphorus content in 20～40 cm soil layer.The soil available phosphorus content of conventional flooding irrigation mode was significantly higher than that of control irrigati on mode(P<0.05).The total phosphorus content of the three-layer soil increased with the increase of fertilizer application rate,and the total phosphorus content of the test soil in 2021 was significantly higher than that in 2020(P<0.05).The results of two years showed that the amount of soil phosphorus increased with the increase of fertilizer application.Under the two irrigation modes,the amount of soil phosphorus in P3 treatment decreased significantly compared with that in P4treatment.The results of two consecutive years showed that under the control irrigation mode,the amount of phosphorus fertilizer reduced by 20%could significantly increase rice yield and phosphorus accumulation in aboveground plants(P<0.05),and the utilization rate of phosphorus fertilizer was significantly higher than that of conventional fertilization.While stabilizing the effective phosphorus content in the 0～20 cm soil layer,the effective phosphorus content in the20～40 cm soil layer was significantly increased,and the annual soil surplus was significantly reduced(P<0.05).The apparent balance of phosphorus was maintained,and there was no adverse effect on basic soil fertility.Based on rice yield and utilization rate of phosphorus fertilizer,the application rate of phosphorus fertilizer with 20%phosphorus reduction under controlled irrigation mode was the best,that is,36 kg/hm~2 of fertilizer application under controlled irrigation mode was the best water and fertilizer management mode in the region. |
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