Impacts Of Long-term Different Fertilization On Maize Yield,Soil Fertility And Greenhouse Gas Emission In Northeast China

Food security and global warming is the major challenges facing human society today.In order to balance economic profit and environmental health,better fertilization should be put forward to improve crop yields and reduce greenhouse gas emissions,which is a major technical requirement for sustainable development of agricultural production.The effect of long-term fertilization on crop production is an important scientific basis for the sustainable development of agriculture.Based on the station of Long-term Experiments on Black Soil Fertility and Fertilizer Use Efficiency?Gongzhuling?,established in 1990,the present study involved nine treatments:no fertilization?CK?,only chemical N fertilizer?N?,only chemical N and P fertilizers?NP?,only chemical N and K fertilizers?NK?,only chemical P and K fertilizers?PK?,balanced chemical fertilizer of NPK?NPK?,NPK with straw?SNPK?,NPK plus pig manure?M₁NPK?,NPK plus high amount pig manure?M₂NPK?.This study aims to explore the sustainability of maize yield,soil fertility changes and the greenhouse gases of CO₂,N₂O and CH₄ emissions,the differences in global warming potential?GWP?and greenhouse gas intensity?GHGI?among different fertilization measures,so as to put forward the best fertilization methods with increasing yield and reducing gas emission,and to provide scientific basis and technical support for agricultural sustainable development in black soil region of Northeast China.1.There were no significant differences in average yields among M₁NPK,SNPK and NPK treatments,in which were applied same N amount.Maize average yields of chemical fertilizer treatments showed an order of NPK>NP>NK>N>PK and CK.The agronomic use effciences of chemical fertilizer N,P and K was 33.0,16.3 and 5.1 kg kg^-1 respectively.The application of organic fertilizer and chemical fertilizer had higher sustainable yield index?SYI?from 0.694 to 0.767,but the SYI was very lower in imbalance fertilization and no fertilizer treatments.The coefficient variation?CV?of maize yield was greater in the CK,PK,N or NK treatments,ranged from 21.2%to 36.9%,while organic and inorganic fertilizer treatment had lower CV between 11.1-14.1%.The contributions fo soil nutrients of N?P and K was 41.8%?85.6%and 95.9%,respectively.The average productivity contribution was 68.9%,91.2%in the N and NPK treatment respectively,There were no significant differences in productivity contribution among the M₁NPK,SNPK and NPK treatments.2.Maize N accumulation amount in the M₁NPK was higher than those of NPK and SNPK treatments at every growing stage?P<0.05?.The N accumulation amounts in the M₁NPK,NPK,SNPK,N and CK treatments reached to 286.2,276.2,249.4,151.7 and 63.6 kg ha^-1 at the maturity,respectively.The total N translocation amounts in leaves and straw-sheath reached to 99,79.7,87.2 and 41.8 kg ha^-1 in the M₁NPK?SNPK?NPK and N treatments,respectively,and the nitrogen contribution ratios reached to 25.5%,23.8%,23.6%and 21.7%,respectively.M₁NPK has the highest N translocation amount and transferred nitrogen contribution ratio among all treatments,which has obviously difference as compared with the other treatments.N use efficiency?NUE?,agronomic nitrogen use efficiencies?ANUE?and partial factor productivities?PFP?in the M₁NPK were obviously higher than that of the NPK treatments,but that of the SNPK treatment had no significant difference with the NPK treatment.PFP and ANUE from the MNPK treatment reached to 65.4 and 44.6kg kg^-1,respectively.3.The diurnal dynamic of soil temperature was a sine wave under different fertilization treatments.During maize growing stage,daily maximum soil temperatures and mean soil temperatures in the M₁NPK and SNPK treatments were significantly lower than that in the NPK treatment?P<0.05?,daily minimum soil temperature and diurnal change range in the SNPK treatment was lower than that in the NPK.Soil moisture of 0-20 cm layer in the CK was the lowest among all treatments,but it was the highest in the 30-90cm layer.Compared to the NPK,the M₁NPK and SNPK treatments could significantly increase soil moisture in the 30-90 cm layer?P<0.05?.Water using efficiency in the M₁NPK was significantly higher than that in the NPK treatment,which was lower than that in the SNPK treatment only in dry season.4.The combination of manure and chemical fertilizer could significantly increase the contents of surface soil organic carbon,active organic carbon,microbial C and N,total N,alkaline hydrolysis N.Soil organic carbon and total nitrogen contents kept stable in the the SNPK,but soil active organic carbon significantly decreased by 36.8%than the initial value in this treatment.The contents of surface soil organic carbon,active organic carbon,total N and alkaline hydrolysis N showed decreasing trends in no fertilizer?CK?and imbalance fertilization?N and NP?treatments.Soil microbial C and N contents in the combination of manure and chemical fertilizer treatments were significantly higher than that of chemical fertilizer treatments?P<0.05?,especially the SNPK was the highest.The increases of soil organic carbon and total N mainly concentrated in 0-40 cm layer in the combination of manure and chemical fertilizer treatments.5.Combination of organic and inorganic fertilizer could significantly increase the contents of soil total phosphorus,available phosphorus and available potassium,while the contents of soil total phosphorus,available phosphorus and available potassium decreased in the CK;Soil total phosphorus and available phosphorus decreased under the fertilized plots without P fertilizer.Soil available potassium decreased if without k application,but applied K could increase soil available potassium.There was no significant difference in total potassium content among all treatments.Effects of different fertilization on soil acidification mainly concentrated in the 0-40cm soil layer,and there was no significant difference in soil pH bellow the 60 cm soil layer.Applied chemical fertilizer treatments had lower soil pH than the CK and the combination of organic and inorganic treatments;The pH valus of the NPK was 1.6,2.17 lower compared to the M₂NPK and SNPK in 2012.6.The emission peaks of soil CO₂ and N₂O appeared during maize jointing stage.In the whole growth period,SNPK treatment showed the highest soil CO₂ flux with an accumulation amount about 5595.4 kg ha^-1.CK treatment had the lowest soil CO₂ flux than other treatments,whose accumulation amount reached to 3147 kg ha^-1.Accumulation amounts of soil CO₂ in combined application of organic and inorganic fertilizer?SNPK and M₂NPK?were significantly higher than those of chemical fertilizer treatments?P<0.05?.Soil N₂O emissions of combined manure and chemical fertilizer?M₂NPK?treatment were significantly higher than that of chemical fertilizer treatment,which was significantly higher than that of no fertilizer?CK?treatment;Moreover,SNPK treatment had less soil N₂O emissions than fertilizer NPK treatment.Net soil CH₄ uptake in organic and inorganic fertilizer treatments?M₂NPK and SNPK?was significantly higher than that of no fertilizer?CK?and N treatment?P<0.05?.As far as soil GWP and GHGI were concerned,the treatments of N and NPK increased GWP by 109.8%and 31.5%,respectively,SNPK treatment decreased GWP by 13.2%as compared with the CK.Soil GHGI in the NPK,SNPK and M₂NPK treatments was lower than that of CK and N treatments significantly.Soil GHGI in the M₂NPK and SNPK treatments reached to^-183.5 and 59.6kg CO₂-e t^-1 respectively.