Effects Of Alternate Partial Root-zone Drip Fertigation On Tomato,Watermelon Growth And The Fertilizer-nitrogen Utilization And Its Movement

Unreasonable irrigation and the use of water and nitrogen are not only bad for crop yield improvement,and may cause the waste of water and nitrogen resources and environmental pollution at the same time.Alternate partial root-zone drip irrigation?APRDI?is proved to be effective in water saving.However,at present,the research on alternate irrigation is limited to the different irrigation limits as well as the different effects of different irrigations on the physiological aspects of plant yield,fruit quality and photosynthetic rate.There are a few studies on alternate irrigation for water and fertilizer integration.For the APRDI,nitrogen and water coupling,the effects of plants on water and nitrogen uptake and utilization,and the migration and distribution of nitrogen are rare.In this study,the plant growth and the uptake of N,P and K,and the migration and utilization of fertilizer nitrogen were studied.It provides a scientific basis for the efficient utilization of water and fertilizer in alternate root zone drip fertigation,as well as the effect of fertilizer nitrogen on the environment.The main research results are as follows:?1?From the tomato field experiment,different irrigation methods?flood irrigation,conventional drip irrigation,alternate drip irrigation?,irrigation level?high water,medium water,low water?and fertilization level?high fertilizer,medium fertilizer and bottom fertilizer?were set up.The results showed that under different irrigation methods,the biomass of tomato fruit decreased with the decrease of nitrogen application rate.Under the same irrigation and nitrogen application,the yield and water use efficiency of alternating drip irrigation and the biomass of root weight were higher than that of the flood irrigation and the conventional drip irrigation.And compared with the conventional irrigation,the alternating drip irrigation can save 33.3%water usage without reducing the yield.Under the same irrigation and fertilization,the root length of the alternate drip irrigation at 20-40cm was higher than that of the conventional drip irrigation.the photosynthetic rate of alternate drip irrigation was higher than that of conventional drip irrigation,and the average rate was 17.7%during the fruit swelling period.The photosynthetic rate of alternate drip irrigation was 7.4%higher than that of the conventional drip irrigation during the full productive age.When the amount of irrigation and nitrogen application was the same,the content of nitrate nitrogen in the 0-40 section of the soil surface was higher than that of the conventional drip irrigation and flood,and gets the maximum value in the treatment of A50/75?5.72g/layer??2?From the simulated soil column test,it showed that the absorption of ¹⁵N increased with the increase of irrigation and nitrogen application,while the residual amount of ¹⁵N decreased with the increase of soil depth.The content of ¹⁵N in the surface decreased with the increase of irrigation water,and increased with the increase of nitrogen application.The less the amount of nitrogen applied,the less the loss of ¹⁵N was,but the loss rate was less.Under the same irrigation and nitrogen application,the ¹⁵N utilization rate and the surface ¹⁵N residue of the alternate drip irrigation were higher than that of the conventional drip irrigation,in which the total utilization rate of A50/100 was 10.6%higher than that of C50/100,and the ¹⁵N residue of A50/100 and A50/50 increased by 7.6%and 15.3%compared with C50/100 and C50/50,and the ¹⁵N loss of the alternate drip irrigation under the same water and nitrogen supply was under the same water and nitrogen supply.The loss rate was lower than that of conventional drip irrigation,and the ¹⁵N loss rate decreased by 29.4%³7.8%compared with conventional irrigation.?3?From the watermelon field experiment,it was found that under the same irrigation fertilizer rate,the production of APRDI higher than conventional drip irrigation,and reached the maximum in leisure processing,the CLH increased by 11.3%,and the CHH processing also has a significant increase.This indicates that alternative drip irrigation can maintain a higher yield than conventional drip irrigation with a decrease of 40.7%drop in moisture.And the content of nitrate nitrogen in the deep soil increased with the increase of the nitrogen application;the content of nitrate nitrogen in deep soil increased with the increase of irrigation amount and the number of irrigation and fertilization;the nitrate nitrogen content in the surface 0-20cm of the alternate drip irrigation was higher than that of the conventional drip irrigation;under the same water and nitrogen treatment,the content of nitrate nitrogen in soil was higher than that of the conventional drip irrigation.Compared with the conventional drip irrigation,the nitrate nitrogen concentration near the alternate drip irrigation drops was higher,while the nitrate nitrogen content of the conventional drip irrigation at the edge area was higher,and the nitrate nitrogen content in the alternate drip irrigation was significantly higher than that of the conventional drip irrigation,and the average nitrate nitrogen concentration of CLH and CLL within the center radius of 10cm was51.92mg/kg and 34.79mg/,respectively,in the 10cm near the root system.While the average nitrate nitrogen concentrations of ALH and ALL were 88.67mg/kg and 78.24mg/kg,respectively,which were 70.8%and 124.9%higher than those of conventional drip irrigation.To sum up,drip irrigation in alternating root zone can promote plant root growth,increase photosynthesis rate,as well as crop yield and water use efficiency.At the same time,compared with the commen drip irrigation,drip irrigation in alternate root zone can reduce the amount of leaching of nitrate nitrogwen in soil,so that nitrogen can remain more residue in soil surface,thus reducing nitrogen fertilizer.And reduce pollution of environment and improve the efficiency of nitrogen absorption and utilization by plants at the same time.