Effects Of Biochar And Nitrification Inhibitors On The Distributions Of Soil Carbon And Nitrogen And Their Gaseous Losses In Greenhouse Grape Cultivation

With the increasing demand in the market and the intensification of agriculture,the area under facility viticulture has been on the rise.However,heavy fertilization has led to significant losses and low utilization of soil nutrients,particularly in the cyclic transformation of soil carbon and nitrogen nutrients.This not only affects the uptake and utilization of grapes but also contributes to gaseous losses,which can trigger the greenhouse effect.To address this issue,a study was conducted to compare the effects of a control treatment with no nitrogen application,a traditional nitrogen application treatment,and an optimized nitrogen application treatment.The latter included the addition of nitrification inhibitor(DMPP)at 1%,2%,and 3%of nitrogen application,biochar at 0.5%,1.5%,and 2.5%of soil weight,and the intermixing of DMPP and biochar.The aim was to monitor the characteristics of soil N2O,NH3,CO2,and CH4 emissions and to determine the optimal amount and ratio of biochar to DMPP.The study analyzed the characteristics of soil carbon and nitrogen distribution and its gaseous loss in facility grapes,combined with grape yield,quality,and economic benefits.The findings provide a theoretical basis and technical support for high-quality and efficient environmental protection in facility grapes.The main results showed that:(1)The study aimed to determine suitable dosages and ratios of biochar and DMPP for suppressing emissions of N2O,NH3,CO2,and CH4 from facility vineyard soils.Results showed that DMPP had a significant inhibitory effect on soil N2O,with cumulative emissions reduced by 84.78%to 96.42%.The best inhibitory effect was observed with DMPP with 2%N application.However,the inhibitory effect of DMPP on other soil gases was not significant.On the other hand,biochar showed inhibitory effects on soil N2O,NH3,CO2,and CH4,with cumulative emissions decreasing by 56.90%to 83.46%,8.44%to 15.90%,8.52%to 16.59%,and 34.79%to 39.03%,respectively.The best effect was observed with 1.5%biochar dosage.Analysis of the GWP of the four gases revealed that the GWP of 1.5%biochar with 2%DMPP was 26.27 mg· g-1,significantly lower than the other treatment combinations.(2)The application of biochar and DMPP can not only suppress emissions of greenhouse gases but also improve the quality and yield of grapes,leading to increased economic benefits.Compared to conventional nitrogen application,the use of biochar and DMPP increased yield by 33.42%to 36.80%,economic benefit by 33.80%to 37.30%,and agronomic benefit by 31.99%to 188.14%.Additionally,it reduced fruit acidity and increased soluble solids content.The best enhancement effect was observed with 1.5%biochar in combination with 2%DMPP.(3)The application of biochar with DMPP resulted in enhanced soil carbon and nitrogen content.As the growth period extended,the nitrate nitrogen content and organic carbon content in different soil layers increased by 11.16%to 63.85%and 13.95%to 47.22%,respectively.The combination of 1.5%biochar and 2%DMPP increased NO3--N content in the 0～60 cm soil layer and reduced NO3--N leaching from the 60～100 cm deep soil layer compared to conventional N application.Moreover,the organic carbon content of the 0～100 cm soil layers increased to varying degrees,ranging from 11.50%to 44.76%.(4)The application of biochar with DMPP significantly reduced the gaseous loss of soil carbon and nitrogen.Compared to 2%DMPP alone,the use of 1.5%biochar with 2%DMPP resulted in significantly lower cumulative CO2 emissions and NH3 volatilization by 10.68%and 16.54%,respectively.However,there was no significant difference in cumulative N2O and CH4 emissions.Moreover,compared to 1.5%biochar application alone,the cumulative CH4 emissions increased by 31.75%,and there was no significant difference in other gases.The analysis revealed that soil inorganic N content was significantly correlated with carbon and N gaseous losses.The nitrate-nitrogen content of surface soils was highly positively correlated with soil N2O emissions(r=0.547**,P<0.01)and negatively correlated with soil CO2 emissions(r=-0.596*,P<0.05).Additionally,the ammonium N content of surface soils was highly positively correlated with soil NH3 volatilization(r=0.729**,P<0.01).However,there was no significant correlation between soil inorganic nitrogen and soil CH4 emission.(5)The application of biochar and DMPP can significantly reduce the net greenhouse effect of facility vineyards.The net greenhouse effect of 1.5%biochar,2%DMPP,and the combination of both was 6663.63,6312.99,and 6332.55 kg-hm-2,respectively,which decreased by 18.27%to 24.53%compared to conventional nitrogen application.Soil CO2 and N2O emissions were identified as the main factors affecting the net greenhouse effect,contributing 51.08%to 59.08%and 20.97%to 27.30%,respectively.In conclusion,the addition of 1.5%biochar by weight and 2%DMPP by pure nitrogen content is an effective measure for soil carbon and nitrogen regulation in facility vineyards in Hebei Province.This approach can improve soil quality,yield,and efficiency,increase soil carbon and nitrogen content,and significantly reduce gas loss.