| To explore the effects of biochar on rice nitrogen absorption and utilization,nitrogen transports efficiency,nitrogen fertilizer productivity,rice dry matter production and transport,yield and quality formation in soda saline-alkali paddy fields.The experiment was conducted in the soda saline-alkali land comprehensive experimental base of Jilin Agricultural University in Sheri Town,Da ’an City,Jilin Province from 2019 to 2020.Changbai 9,the main local rice variety,was used as the test variety.Split-plot designs was adopted in the experiment,with nitrogen fertilizer application rate in the main area and different biochar application rates in the secondary area.Two nitrogen application rates,no nitrogen fertilizer =(N0)and 250 kg/hm2 pure nitrogen =(N2),were set in the main experimental area.There are four biochar treatments of the sub-districts: no carbon treatment(B0),33.75 t/hm2 carbon applications(B1),67.50t/hm2 carbon application(B2)and 101.25 t/hm2 carbon application(B3).By measuring the indexes of rice nitrogen accumulation,nitrogen productivity,nitrogen utilization efficiency,nitrogen transportation and transportation rate,the dry matter accumulation,transportation and efficiency of rice and the yield components of rice were compared,and the differences of quality traits were analyzed,so as to clarify the influence of biochar on rice nitrogen absorption,utilization and transportation in soda saline-alkali soil.The main results are as follows:1.The application of biochar has a significant effect on nitrogen absorption and transport of rice in soda saline-alkali land.B3 > B2 > B1 > B0 in two years.The total nitrogen accumulation in mature stage was the highest in B3 treatment,and B1,B2 and B3 increased by5.7%,10.8% and 17.24% on average compared with B0 under the condition of N0.Under N2 condition,B1,B2 and B3 increased by 5.47%,12.05% and 22.53% on average compared with B0,and the total nitrogen accumulation of biochar treatment was significantly higher than that of no biochar treatment.With the increase in biochar application rate,the nitrogen transports amount and rate from heading stage to maturity stage showed B3 > B2 > B1 > B0,and the nitrogen transport amount and rate of biochar treatment B3 was significantly higher than that of B0 treatment.2.Application of biochar has a significant effect on nitrogen utilization of rice in soda saline-alkali land.The application of biochar significantly improved the partial productivity,agricultural utilization rate and absorption utilization rate of nitrogen fertilizer,which showed B3 > B2 > B1 > B0 in two years.The partial productivity of B1,B2 and B3 increased by 8.64%,24.56% and 37.79% on average compared with B0.The agricultural utilization rate of nitrogen fertilizer increased by 7.42%,21.03% and 38.91% on average;The absorption and utilization rates of nitrogen fertilizer increased by 5.29%,13.29% and 27.68% on average;The partial productivity,agronomy utilization rate and absorption utilization rate of nitrogen fertilizer of biochar treatments(B3,B2,B1)were significantly higher than those of no biochar treatment(B0).3.Application of biochar has a significant effect on rice dry matter production and transportation in soda saline-alkali land.The application of biochar significantly increased the dry matter accumulation of rice in each growth period,which showed B3 > B2 > B1 > B0 in two years.Under the condition of N0,B1,B2,B3 of biochar returning to field increased by 14.88%,34.07% and 69.06% on average compared with B0.Under N2 condition,the treatments B1,B2,B3 with biochar returning to field increased by 10.07%,14.19% and 23.48% on average compared with B0,and the dry matter accumulation of each treatment(B3,B2,B1)with biochar was significantly higher than that without biochar(B0).With the increase in application amount of biochar,the dry matter transports amount and transport rate of heading stage to maturity stage showed B3 > B2 > B1 > B0,and the difference in dry matter transport amount and transport rate for biochar treatment B3 and B2 and B1 was significant.The dry matter transport capacity and transport rate of B2 were significantly higher than those of B0.4.Application of biochar has a significant effect on rice yield and yield components in soda saline-alkali land.Biochar significantly increased the effective panicle number,grain number per panicle and seed sett rate of rice,which showed B3 > B2 > B1 > B0 in two years.Biochar treatment B3 and B2 were significantly higher than the control(B0),and the effective panicle number of Biochar treatment B3 was significantly higher than B2.Under N0 condition,the yields of B1,B2 and B3 treated with biochar increased by 9.9%,28.1% and 36.72% on average compared with B0 treatment.Under N2 condition,the yields of B1,B2 and B3 treated with biochar increased by 8.6%,24.56% and 37.79% on average compared with B0 treatment.The application of biochar can significantly increase rice yield,and the increase in panicle number,grain number per panicle and seed sett rate is the main factor for the increase of rice yield.5.Biochar can significantly improve rice quality of soda saline-alkali soil.The application of biochar significantly improved the brown rice rate,milled rice rate and milled rice rate,which showed B3 > B2 > B1 > B0.At the same time,the application of biochar significantly improved the whiteness,refined whiteness and permeability of rice,which showed B3 > B2 > B1 > B0.The application of biochar significantly improved the protein,chalkiness and amylose content of rice,and decreased to the increase of biochar application,which showed B0 > B1 > B2 > B3.Application in biochar can significantly improve rice quality,and the effect of high application rate(B3)is the best.To sum up,application of biochar can improve rice nitrogen absorption efficiency,increase rice nitrogen accumulation,transportation and transportation rate,improve nitrogen absorption and utilization efficiency,and be beneficial to rice dry matter production,thus increasing rice dry matter accumulation,transportation and transportation rate,increasing effective panicle number,grain number per panicle and seed sett rate,promoting yield formation and improving rice quality.The results provide theoretical support for comprehensive utilization of soda saline-alkali land. |
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