Study On Regional Characteristics Of Heat And Precipitation And Suitable Tillage Methods In Northeast Plain

Northeast Plain of China is composed of the Sanjiang Plain,Songnen Plain and Liaohe Plain,spanning Heilongjiang,Jilin,Liaoning and Inner Mongolia provinces(autonomous regions).As an important commodity grain base in China,the Northeast Plain plays an important role in realizing food security.Climate change leads to significant changes in the spatial and temporal pattern of agricultural climate resources in China,which affects the growth and development of crops to varying degrees.Tillage measures affect soil temperature,moisture and microbial activity,and the requirements of tillage measures are different in different climatic regions.At present,there is a lack of systematic research on the regional variation characteristics of heat and precipitation,their effects on crop yields,and the matching between tillage methods and the variation rules of major climate factors in the Northeast Plain.Fifteen representative weather stations were selected in the Northeast Plain,and 6 stations were selected in the Songnen Plain:Nenjiang,Helen,Qiqihar,Harbin,Baicheng and Changchun;Sanjiang Plain selected four stations:Tongjiang,Fujin,Jiamusi,Baoqing;Liaohe Plain selected five stations:Siping,Tongliao,Fuxin,Shenyang,Anshan.Based on the daily temperature,first frost and last frost days,precipitation and evaporation of these meteorological stations from 2000 to 2019,the characteristics of climate change in the Northeast Plain were analyzed.The ARIMA model was used to predict the variation of active accumulated temperature and frost-free period from 2020 to 2027 and the impact on crop yield.Combined with the experimental data from 2018 to 2019 in the long-term positioning area of Xiangyang Experimental Base of Northeast Agricultural University(Harbin City,Heilongjiang Province),Five tillage treatments were set in the experiment,which were traditional tillage(TT)? no-tillage(NT)? under no-tillage and no seeding deep ridge ditch at seedling stage(NT+S)? deep ridges in the ridges and ridges + deep stalks at seedling stage(S+S)under straw mulching,under the condition of no straw returning to field,stubble-removing rotary tillage ridging and seedling ridging deep loosening(CK)as control.Results show that:(1)The accumulated active temperature in Songnen Plain,Sanjiang Plain,Liaohe Plain and the western part of Northeast Plain from 2000 to 2019 is 3153.4?·d,2933.6?·d,3526.6?·d and 3264.4?·d;According to the model prediction,the active accumulated temperature in the four regions of the Northeast Plain from 2020 to 2027 is 3258.4?·d,2967?·d,3609.7?·d and3317.1?·d,respectively,with a slight increase.It is favorable to the formation of soybean,corn and rice yield.(2)The frost-free periods of Songnen Plain,Sanjiang Plain,Liaohe Plain and the western part of Northeast Plain from 2000 to 2019 are 161 d,162 d,173 d and 166 d.According to the model prediction,the frost-free period of the four regions in the Northeast Plain from 2020 to 2027 is168.1 d,172.9 d,178.8 d and 176.7 d,respectively,with a slight increase.The advance of the last frost date and the delay of the first frost date have an effect on the increase of the frost-free period,and the advance of the last frost date plays a leading role.(3)During the growth period of crops in the Northeast Plain from 2000 to 2019,rainfall tendency rate increased in the order of Sanjiang Plain(16.6mm/a)> in Liaohe Plain(8.24mm/a)>in Songnen Plain(8.0mm/a)> in the western part of the Northeast Plain(7.3mm/a);The trend rate of spring rainfall in Liaohe Plain(2.2mm/a)> in Sanjiang Plain(1.8mm/a)> in Songnen Plain(1.5mm/a)> in the western part of Northeast Plain(1.4mm/a);The tendency rate of summer rainfall in Liaohe Plain(7.1mm/a)> in Sanjiang Plain(2.4mm/a)> in Songnen Plain(2.1mm/a)> in the western part of Northeast Plain(0.3mm/a);The tendency rate of autumn rainfall in Sanjiang Plain(7.8mm/a)> in the western part of Northeast Plain(4.5mm/a)> in Songnen Plain(4.1mm/a)> in Liaohe Plain(3.8mm/a).(4)The ratio of precipitation to active accumulated temperature(water-heat ratio)during crop growth period can measure the matching of water and heat.From 2000 to 2019,the order of water-heat ratio during crop growth in the Northeast Plain was as follows:Sanjiang Plain(15.45mm/100?)> Liaohe Plain(14.40mm/100?)? Songnen Plain(14.39mm/100?)> the west of Northeast plain(12.68mm/100?).The order of water-heat ratio during spring in the Northeast Plain was as follows : Sanjiang Plain(15.54mm/100?)> Songnen Plain(11.62mm/100?)>Liaohe Plain(10.05mm/100?)> the west of Northeast plain(9.56mm/100?);The order of water-heat ratio during summer in the Northeast Plain was as follows : Songnen Plain(17.11mm/100?)> Sanjiang Plain(15.82mm/100?)> the west of Northeast plain(14.62mm/100?)>Liaohe Plain(14.51mm/100?);The order of water-heat ratio during autumn in the Northeast Plain was as follows:Sanjiang Plain(15.23mm/100?)> Liaohe Plain(14.10mm/100?)> Songnen Plain(12.85mm/100?)> the west of Northeast plain(11.11mm/100?).The water-heat ratio showed that there was sufficient precipitation in the Sanjiang Plain in spring,while the western part of the Northeast Plain was dry.In summer,the Songnen Plain had sufficient precipitation,while the Liaohe Plain and the western Northeast Plain were rather dry in summer.In autumn,Sanjiang Plain has sufficient precipitation and the western part of Northeast Plain is dry.(5)The order of soil water content under spring tillage is no-tillage(NT)> under no-tillage and no seeding deep ridge ditch at seedling stage(NT+S)> stubble-removing rotary tillage ridging and seedling ridging deep loosening(CK)> deep ridges in the ridges and ridges + deep stalks at seedling stage(S+S)> traditional tillage(TT).NT and NT+S had better drought resistance than other treatments.The accumulated soil temperature at 10 d,20d and 30 d after sowing was CK >TT > S+S > NT+S > NT.The total accumulated soil temperature of all treatments was CK > TT >NT+S > S+S > NT at 40 d,50d and 60 d after sowing.In the northern part of Sanjiang Plain and Songnen Plain,there is sufficient precipitation in spring,but the heat condition is a little insufficient.Under the condition of straw returning to field,the tillage methods of traditional tillage(TT)or under no-tillage and no seeding deep ridge ditch at seedling stage(NT+S)can be chosen.In the western part of Northeast Plain and the southern part of Songnen Plain,there is less precipitation in spring,so the tillage methods of no-tillage mulch(NT)or under no-tillage and no seeding deep ridge ditch at seedling stage(NT+S)can be selected.In the Liaohe Plain,the water and heat conditions are sufficient,but the precipitation matching with the heat is slightly insufficient.The tillage methods of no-tillage mulch(NT)or under no-tillage and no seeding deep ridge ditch at seedling stage(NT+S)can be selected.