Investigating The Mechanisms Of Ridge-furrow With Plastic Film Mulching And Fertilization On Potato Yields And Greenhouse Gas Emissions In Hilly Area Of The Loess Plateau

Water resources shortage,low soil fertility and crops yield,and greenhouse gas emissions,they limited sustainable development of agricultural production in arid and semi-arid regions.The positive effects of ridge-furrow with plastic film mulching on crop yield and water use efficiency have attracted much attention in dryland area.The combination of ridge-furrow with plastic film mulching with controlled-release urea will inevitably cause changes in soil moisture and nutrients,which in turn will affect crop production and greenhouse gas emissions,but the mechanisms of their impact on potato productivity and the environment are unclear.Therefore,it is essential to carry out research on the application effects and evaluation of the environmental benefits of controlled-release urea under ridge-furrow with plastic film mulching.In this study,potato（Solanum tuberosum L.）Kexin No.1 was used as the test material.Treatments consisted of two mulching modes[RM and without plastic film mulching（NM）],combined with three urea types[no fertilizer（N0）,common urea（U）,controlled-release urea（C）,and mixed C and U at a ratio of 1:1（CU）].A three-year field trial was conducted in the dry hilly area of the Loess Plateau in Inner Mongolia.The effects of ridge-furrow with plastic film mulching and fertilization application on soil water and temperature,nutrients,enzyme activity and microbial community structure and greenhouse gas emissions in dry crop potato fields were studied.The main findings are as follows:1.The ridge-furrow with plastic film mulching significantly increased soil water storage from 0-60 cm,especially ridge-furrow with plastic film mulching significantly increased topsoil water storage by 13.57%.CU promoted soil water use in the mid-growth of potatoes in topsoil（CU increased by 3.42%and 5.39%compared to U and C,respectively）and reduced soil water storage.Compared to NMU,RMU,RMC and RMCU increased 0-60 cm soil water storage by 5.41%,5.03%and 3.14%（normal rainfall 2018）;9.08%,10.57%and6.57%（drought 2019）and 7.63%,8.18%and 6.09%（drought 2020）,respectively.The ridge-furrow with plastic film mulching significantly reduced evapotranspiration of potato field in the early stages by 7.18 mm,but significantly increased evapotranspiration in late stages by 3.52 mm,compared to NM.The The ridge-furrow with plastic film mulching can regulate the soil temperature of 0-10 cm layer.Over the three growing seasons,the ridge-furrow with plastic film mulching increased soil temperature by 1.55°C,1.39°C and 143°C respectively.The warming effect was mainly reflected in the early growing season,and gradually decreased with the expansion of the potato canopy.Three fertilization methods（U,C and CU）had no significant effect on soil temperature during the growing season.2.The ridge-furrow with plastic film mulching increased SOC and TN consumption within growing season.U and CU treatments increased SOC and TN consumption within growing season.The SOC and TN were 127.02 and 16.02 mg kg^-1 higher in RMU,49.82and 7.93 mg kg^-1 higher in RMC,170.42 and 18.82 mg kg^-1higher in RMCU than NMU.The soil enzyme activity was consistently enhanced under ridge-furrow with plastic film mulching.Compared to NMU,RMU,RMC and RMCU increased soil urease,alkaline phosphatase,invertase and soil enzyme index by 6.94%,4.96%and 11.10%,3.32%,1.49%and 0.44%,4.24%,6.49%and 10.07%,and 4.24%,6.49%and 10.07%,respectively.3.Ridge-furrow with plastic film mulching increased bacterial community richness and diversity,and reduced the copiotrophic bacteria phyla Proteobacteria and Gemmatimonadota,increased the oligotrophic bacteria Firmicutes,Chloroflexi,Acidobacteriota.Compared to N0,fertilization reduced the richness and diversity of the bacterial community,and increased the copiotrophic bacteria phyla Proteobacteria and Gemmatimonadota,while decreased the oligotrophic bacteria Acidobacteriot and Chloroflexi.Ridge-furrow with plastic film mulching increased the diversity but reduced the abundance of fungal communities.Fertilization application reduced the richness and diversity of the soil fungal community.Bacterial function predicted by FAPROTAX,the result indicated ridge-furrow with plastic film mulching and fertilization can improve the microbial community involved in nitrogen cycle in the soil,such as aerobic＿ammonia＿oxidation,nitrification,nitrogen＿respiration and nitrate＿respiration.Fungal function predicted by FUNGuild indicated that soil Undefined＿Saprotroph,Plant＿Pathogen,and Endophyte were more abundant.Ridge-furrow with plastic film mulching and fertilization reduced the relative abundance of plant pathogen,eg.ridge-furrow with plastic film mulching reduced Gibberella by 19.12%and fertilization mainly reduced Fusariu and Gibberella by 27.71%and 34.27%respectively.4.Ridge-furrow with plastic film mulching increased total links,clustering coefficients,graph density and average degree in the molecular ecological networks by bacterial and fungal,which made the ecological networks more complex.Fertilization only increased modularity in the molecular ecological networks.The number of Proteobacteria nodes was the highest among bacterial nodes,followed by Firmicutes,Bacteroidota and Actinobacteriota,while the number of Ascomycota nodes was the highest among fungal nodes,followed by Basidiomycota and Mortierellomycota.5.The ridge-furrow with plastic film mulching effectively promoted potato growth,increased plant height,stem diameter,leaf Chl and NBI,and decreased leaf Flav.Importantly,CU improved leaf Chl and NBI of potato in the late growth stage.Compared to NMU,RMU,RMC and RMCU increased plant height by 4.75%,1.97%and 6.03%,leaf Chl by 2.11%,2.05%and 5.23%,leaf NBI by 3.91%,3.25%and 7.89%,respectively.Meanwhile,RMU,RMC and RMCU decreased leaf Flav by 1.67%,1.81%and 3.01%,respectively compared to NMU.6.Ridge-furrow with plastic film mulching improved weight and number of large potatoes,ultimately increased yields.Compared with NMU,RMU,RMC and RMCU clearly improved the weight and number of large tubers by 16.42%,12.44%and 28.60%,11.78%,-1.70%and 15.90%,respectively.Thus,tuber yield was significantly higher in RMU,RMC and RMCU than NMU by 10.62%,8.04%and 21.75%,respectively.Ridge-furrow with plastic film mulching supported high-level resource utilization,especially for use of water/fertilization use efficiency.Cmpared to NMU,RMU,RMC and RMCU significantly increased WUE,PFPN and AE by 11.78%,9.68%and 21.4%,10.62%,8.04%and 21.75%,14.37%,5.63%and 52.15%,respectively.7.The ridge-furrow with plastic film mulching significantly suppressed cumulative CH₄ uptake and reduced cumulative N₂O emissions within growing season,but had no significant effect on cumulative CO₂ emissions.Three fertilization methods significantly increased cumulative CO₂ and N₂O emissions and reduced cumulative CH₄ uptake.The differences between the U and CU treatments were not significant.Under RMU,RMC and RMCU cumulative CH₄ uptake and N₂O emission were decreased by 29.45%,25.18%and27.40%,5.77%,18.68%and 11.33%respectively,compared to NMU.8.The order of contribution of different agricultural input items to total life-cycle GHGs was reversed:Nitrogen fertilization>Fuel>Plastic film>GHGs>PK fertilization>Pesticides.Ridge-furrow with plastic film significantly increased NGWP by 11.30%,compared to NM.Under U,C and CU significantly increased NGWP by 320.24%,312.46%and 316.86%.RMCU and NMCU carbon footprint were 11.82%and 5.49%lower than NMU.Compared with NMU,RMU and RMCU increased the net ecosystem economic budget by 8.52%and 27.89%,respectively,and also had the potential benefits for farmers to increase the net income of 18749.09 and 22045.96 yuan hm^-2,respectively.In conclusion,these findings suggest that ridge-furrow with plastic film with mixture of controlled-release and normal urea is an environment-friendly,high-yield,high-economic benefit suitable for dry cropping potato production system in hilly area of the Loess Plateau.