Consequences of rainforest conversion to smallholder rubber and oil palm plantations on soil trace gas fluxes from highly weathered soils in Sumatra, Indonesia

Abstract. Oil palm (Elaeis guineensis) and rubber (Hevea brasiliensis) plantations cover large areas of former rainforest in Sumatra, Indonesia, supplying the global demand for these crops. Although forest conversion is known to influence soil nitrous oxide (N2O) and nitric oxide (NO) fluxes, measurements from oil palm and rubber plantations are scarce (for N2O) or nonexistent (for NO). Our study aimed to (1) quantify changes in soil–atmosphere fluxes of N oxides with forest conversion to rubber and oil palm plantations and (2) determine their controlling factors. In Jambi, Sumatra, we selected two landscapes that mainly differed in texture but were both on heavily weathered soils: loam and clay Acrisol soils. Within each landscape, we investigated lowland forests, rubber trees interspersed in secondary forest (termed as jungle rubber), both as reference land uses and smallholder rubber and oil palm plantations as converted land uses. In the loam Acrisol landscape, we conducted a follow-on study in a large-scale oil palm plantation (called PTPN VI) for comparison of soil N2O fluxes with smallholder oil palm plantations. Land-use conversion to smallholder plantations had no effect on soil N-oxide fluxes (P = 0. 58 to 0.76) due to the generally low soil N availability in the reference land uses that further decreased with land-use conversion. Soil N2O fluxes from the large-scale oil palm plantation did not differ with those from smallholder plantations (P = 0. 15). Over 1-year measurements, the temporal patterns of soil N-oxide fluxes were influenced by soil mineral N and water contents. Across landscapes, annual soil N2O emissions were controlled by gross nitrification and sand content, which also suggest the influence of soil N and water availability. Soil N2O fluxes (µg N m−2 h−1) were 7 ± 2 to 14 ± 7 (reference land uses), 6 ± 3 to 9 ± 2 (rubber), 12 ± 3 to 12 ± 6 (smallholder oil palm) and 42 ± 24 (large-scale oil palm). Soil NO fluxes (µg N m−2 h−1) were −0.6 ± 0.7 to 5.7 ± 5.8 (reference land uses), −1.2 ± 0.5 to −1.0 ± 0.2 (rubber) and −0.2 ± 1.2 to 0.7 ± 0.7 (smallholder oil palm). To improve the estimate of soil N-oxide fluxes from oil palm plantations in this region, studies should focus on large-scale plantations (which usually have 2 to 4 times higher N fertilization rates than smallholders) with frequent measurements following fertilizer application.

To understand the fluxes of soil greenhouse gases from Alpine meadows on the Qinghai-Tibet plateau during non-growing season, a static chamber method was used to sample gases of soil CO2, CH4 and N2O from alpine meadow on the plateau of Southern Qinghai province during snow cover period, and gas chromatography was used to analyze concentrations of these gases. The results showed that soil CO2 flux was 1.33 g·(m2·h)-1, soil CH4 flux was -0.19 mg·(m2·h)-1, and soil N2O flux was 0.21 mg·(m2·h)-1 when the snow depth was 9-10 cm on March 3 and 4 during the prevalence period of snow cover; soil CO2 flux was 4.70 g·(m2·h)-1 ,and soil N2O flux was 0.24 mg·(m2·h)-1, and soil CH4 flux was -1.23 mg·(m2·h)-1 when the snow depth was 8-9 cm on April 30 during the end period of snow cover. And soil CO2 and N2O fluxes were low or negative, soil CH4 flux was negative and its absolute value was low when the snow depth was less than 4 cm during snow cover period. In addition, soil CO2 or N2O flux was positively correlated with the snow depth, and soil CH4 flux was negatively correlated with the snow depth (P<0.05). Additionally, soil CO2 or N2O flux was negatively correlated with CH4 fluxes, and soil CO2 was positively correlated with soil N2O flux. In addition, soil CO2 flux was the highest during the growing season, followed by the end period of snow cover, and it was the lowest during the prevalence period of snow cover; soil N2O flux was high during the growing season, followed by the end period of snow cover, and it was the lowest during the prevalence period of snow cover; soil CH4 flux was negative, and its absolute value was higher during the growing season than other seasons, and it was the lowest during the prevalence period of snow cover. The results suggested that the change in snow cover would influence the fluxes of soil greenhouse gases from alpine meadow on the Qinghai-Tibet plateau.

Different variations in soil CO2, CH4, and N2O fluxes and their responses to edaphic factors along a boreal secondary forest successional trajectory

Over the last two decades, Sumatra, Indonesia has experienced rapid expansion of rubber and oil palm plantations through conversion of rainforests. This is evident from the 36% decrease in forest area in this region from 1990-2010. Such rapid land-use change necessitates assessment of its environmental impacts. Forest conversion to rubber and oil palm plantations are expected to increase nutrient leaching losses and decrease nutrient retention efficiency, following the changes in soil cover, litter input, soil nutrient availability and management practices. This thesis presents two studies, which focused on the impact of forest conversion to rubber and oil palm plantations on nutrient leaching and nutrient retention efficiency, and on the difference in nutrient leaching losses between fertilized and frond-stacked areas of oil palm plantations. All studies were conducted in two landscapes of highly weathered soils that mainly differed in texture (loam and clay Acrisol soils), located in the Jambi province, Sumatra, Indonesia. Nutrient leaching losses were measured using suction cup lysimeters installed at 1.5 m soil depth and sampling frequency was bi-weekly to monthly during February to December 2013. In the first study, nutrient leaching losses and nutrient retention efficiency in the soil were measured in four land uses: the reference land uses of lowland forest and jungle rubber (rubber trees interspersed in secondary forest), and the converted land uses of smallholder rubber and oil palm plantations. In each landscape, the first three land uses were represented by four replicate sites and the oil palm by three sites, totaling 30 sites. The results illustrated that for the reference land uses the loam Acrisol soil had higher leaching fluxes of dissolved nitrogen (N) and base cations, and lower retention efficiencies of N and base cations than the clay Acrisol soil. For the converted land uses, management practices such as fertilization and liming in oil palm plantations resulted in higher dissolved N, dissolved organic carbon (DOC), and base cations leaching fluxes, and lower N and base cation retention efficiencies in the soil than the reference land uses. On the other hand, in the unfertilized rubber plantations leaching losses of dissolved N, DOC, and base cations were lower than in the oil palm plantations. Overall, the results showed that clay content and management practices controlled nutrient leaching losses and nutrient retention efficiencies in heavily weathered Acrisol soils of these converted landscapes. In the second study, nutrient leaching losses were measured in fertilized and frond-stacked areas of smallholder oil palm plantations in clay and loam Acrisol soils. The results exhibited higher leaching losses (i.e. N, base cations, total aluminum (Al), total manganese (Mn), total sulfur (S), and chloride (Cl)) in the fertilized area than the frond-stacked area due to pulse rates of applications of mineral fertilizers and lime. At the landscape scale, higher soil nutrient stocks and lower nutrient leaching losses in the clay Acrisol soil compared to the loam Acrisol soil both in the fertilized and frond stack areas were caused by the higher nutrient retention as a result of higher clay content. Combining nutrient leaching losses and nutrient input (i.e. bulk precipitation and fertilizers) with ancillary studies on nutrient output through harvest export provides more comprehensive information about the changes in partial nutrient budgets of N, phosphorus (P), and base cations due to forest conversion to oil palm and rubber plantations. Fertilized oil palm plantations had the lowest annual partial budget of N, calcium (Ca) and magnesium (Mg) due to the high annual leaching losses and harvest export. However, the high negative partial budgets of N, Ca and Mg in oil palm plantations did not significantly decrease those stocks at 1-m soil depth compared to all the other land uses, except for exchangeable Mg in the loam Acrisol landscape. Even though unfertilized rubber plantations have lower leaching losses (e.g. P) than forest, harvest export caused the lower annual partial budget of P. Overall, these results from the two studies suggests for improved management practices on these highly weathered soils through synchronizing rate of application of fertilizer with plant uptake and frequency of fertilizer application.

Canopy soil of oil palm plantations emits methane and nitrous oxide

Emissions of greenhouse gases (GHG) such as CO2 and N2O from soils are affected by many factors such as climate change, soil carbon content, and soil nutrient conditions. However, the response patterns and controls of soil CO2 and N2O fluxes to global warming and nitrogen (N) fertilization are still not clear in subalpine forests. To address this issue, we conducted an eight-year field experiment with warming and N fertilization treatments in a subalpine coniferous spruce (Picea asperata Mast.) plantation forest in China. Soil CO2 and N2O fluxes were measured using a static chamber method, and soils were sampled to analyze soil carbon and N contents, soil microbial substrate utilization (MSU) patterns, and microbial functional diversity. Results showed that the mean annual CO2 and N2O fluxes were 36.04 ± 3.77 mg C m−2 h−1 and 0.51 ± 0.11 µg N m−2 h−1, respectively. Soil CO2 flux was only affected by warming while soil N2O flux was significantly enhanced by N fertilization and its interaction with warming. Warming enhanced dissolve organic carbon (DOC) and MSU, reduced soil organic carbon (SOC) and microbial biomass carbon (MBC), and constrained the microbial metabolic activity and microbial functional diversity, resulting in a decrease in soil CO2 emission. The analysis of structural equation model indicated that MSU had dominant direct negative effect on soil CO2 flux but had direct positive effect on soil N2O flux. DOC and MBC had indirect positive effects on soil CO2 flux while soil NH4+-N had direct negative effect on soil CO2 and N2O fluxes. This study revealed different response patterns and controlling factors of soil CO2 and N2O fluxes in the subalpine plantation forest, and highlighted the importance of soil microbial contributions to GHG fluxes under climate warming and N deposition.

Simulated NH4+-N Deposition Inhibits CH4 Uptake and Promotes N2O Emission in the Meadow Steppe of Inner Mongolia, China

Soil degradation in oil palm and rubber plantations under land resource scarcity

Quantifying and predicting spatio-temporal variability of soil CH4 and N2O fluxes from a seemingly homogeneous Australian agricultural field

Conventional agriculture is the dominant contributor to negative environmental impacts such as the growth in global greenhouse gas (GHG) emissions, and the challenges are likely to increase with the increasing global food demand as well as the agricultural expansion. Agroforestry is a sustainable management practice with strong potential to provide ecosystem services and environmental benefits through increasing carbon sequestration, nutrient availability, water use efficiency and biodiversity, and reducing soil erosion and nitrogen losses. Therefore, the establishment of agroforestry practices offers an opportunity to reduce GHG emissions. Previous studies have showed the effects of agroforestry on soil nitrous oxide (N2O), carbon dioxide (CO2), and methane (CH4) fluxes in many parts of the world. In temperate Europe, the information on the GHG mitigation potential of agroforestry compared to cropland monoculture is still unclear. The present thesis consists of two studies, which was designed to explore whether the conversion of cropland monoculture to agroforestry systems reduces trace gases N2O, CO2, and CH4 emissions from the soil. The study was carried out at three sites varied with soil types in Germany. Each site had adjacent alley cropping agroforestry and cropland monoculture systems and the trees in agroforestry system were planted 1 to 11 years prior to this research. We measured soil N2O, CO2, and CH4 fluxes monthly using vented static chambers at the three sites from March 2018 to January 2020. On each day of gas sampling, soil temperature, water-filled pore space and extractable mineral nitrogen (N) were measured in the top 5 cm. The objective of our first study was to quantify the spatial-temporal dynamics of soil N2O fluxes from cropland agroforestry and monoculture systems, following different crop rotations and fertilization rates. The pattern of soil N2O fluxes were predominantly controlled by soil mineral N in both agroforestry and monoculture systems. The positive relationship between water-filled pore space with soil N2O fluxes during the cropping seasons, indicating soil moisture acts as a limiting factor under N-sufficient conditions. The entire agroforestry systems tended to reduce soil N2O emissions by 9% to 56% compared to monocultures, during the corn phase of the rotation that had typically high fertilization rates. The lowest soil N2O emissions in the unfertilized tree rows (occupied 20% of the agroforestry area) represent a potential for mitigating N2O emissions from croplands. The objective of our second study was to investigate the changes in soil CO2 and CH4 fluxes after conversion from cropland monoculture to alley cropping agroforestry systems. Our results showed that seasonal variations of soil CO2 and CH4 fluxes were strongly regulated by soil temperature and moisture, and the spatial variations were mainly controlled by texture. The establishment of agroforestry systems had no effect on reducing soil CO2 emissions, possibly because there was no significant difference in soil temperature between management systems. Annual soil CH4 uptake in the agroforestry systems was increased by up to 300% compared to monocultures, which may be related to the regulation of trees on soil moisture in agroforestry systems. The present research provides the first insight into the systematic comparison of soil N2O, CO2 and CH4 fluxes from cropland agroforestry and monoculture systems, and it provides a unique dataset for estimating the net balance of carbon emissions after conversion of cropland monoculture to alley cropping agroforestry system in temperate regions. Although soil CO2 emissions showed no differences between management systems, the total annual soil emissions of non-CO2 GHG from agroforestry systems were reduced by 0.22 Mg CO2 eq ha-1 compared to the monocultures. Considering the driving function of soil moisture and mineral N on soil GHG fluxes from cropland agroforestry and monoculture systems, our findings suggest that improved system management (e.g. optimal adjustments of the areal coverages between tree and crop rows) and optimized fertilizer input will enhance the potential of cropland agroforestry for mitigating N2O emissions and increasing CH4 uptake and C sequestration in the long run.

The synergy between forest and plantation is much sought after to maintain the complex role of forest areas. Forest should be managed for its socio-economic and ecological position while land-use change tends towards maximizing economic role. Indonesia is struggling to rehabilitate most of her production forests. Many cases show that the forestlands have been converted into monoculture oil palm or rubber plantation that caused severe ecological degradation and declined forest role in ecosystem maintenance. The government of Indonesia is seeking synergy between these two conflicting land uses types. Forest Management Unit (FMU) has been chosen as a model to carry out day to day management at field level beginning in 2010. Unfortunately, majority FMUs have not been in operation due to limited information at the field level, especially about the willingness of landowners to cooperate in the restoration of the production forest. In Dharmasraya District, West Sumatra, a 33,000 hectare of remaining production forest areas is undergoing deforestation due to forest conversion into oil palm and rubber carried out both by smallholder and large scale oil plantation companies. Based on a household survey among smallholders plantation in Dharmasraya District, West Sumatera Indonesia, the paper presents farmers’ willingness to integrate timber and non-timber plants into their oil palm plantation and discusses its implication for forest management especially in forest restoration management for FMU. The study found that at this time, it is hard for the landowner to integrate a timber tree into their smallholder oil palm and rubber plantation. They value land higher for the farm than for forest. Landowners feel secure with the customary land right than statutory land rights. Hence, the study suggests FMU Dharmasraya intensify forest extension service on forest function and persuade landowners to seek a balance between the ecological and economic role of forestland. More importantly, forest ecosystem service needs a proportional monetary valuation.

Abstract. Remote sensing and inverse modelling studies indicate that the tropics emit more CH4 and N2O than predicted by bottom-up emissions inventories, suggesting that terrestrial sources are stronger or more numerous than previously thought. Tropical uplands are a potentially large and important source of CH4 and N2O often overlooked by past empirical and modelling studies. To address this knowledge gap, we investigated spatial, temporal and environmental trends in soil CH4 and N2O fluxes across a long elevation gradient (600–3700 m a.s.l.) in the Kosñipata Valley, in the southern Peruvian Andes, that experiences seasonal fluctuations in rainfall. The aim of this work was to produce preliminary estimates of soil CH4 and N2O fluxes from representative habitats within this region, and to identify the proximate controls on soil CH4 and N2O dynamics. Area-weighted flux calculations indicated that ecosystems across this altitudinal gradient were both atmospheric sources and sinks of CH4 on an annual basis. Montane grasslands (3200–3700 m a.s.l.) were strong atmospheric sources, emitting 56.94 ± 7.81 kg CH4-C ha−1 yr−1. Upper montane forest (2200–3200 m a.s.l.) and lower montane forest (1200–2200 m a.s.l.) were net atmospheric sinks (−2.99 ± 0.29 and −2.34 ± 0.29 kg CH4-C ha−1 yr−1, respectively); while premontane forests (600–1200 m a.s.l.) fluctuated between source or sink depending on the season (wet season: 1.86 ± 1.50 kg CH4-C ha−1 yr−1; dry season: −1.17 ± 0.40 kg CH4-C ha−1 yr−1). Analysis of spatial, temporal and environmental trends in soil CH4 flux across the study site suggest that soil redox was a dominant control on net soil CH4 flux. Soil CH4 emissions were greatest from habitats, landforms and during times of year when soils were suboxic, and soil CH4 efflux was inversely correlated with soil O2 concentration (Spearman's ρ = −0.45, P &lt; 0.0001) and positively correlated with water-filled pore space (Spearman's ρ = 0.63, P &lt;0.0001). Ecosystems across the region were net atmospheric N2O sources. Soil N2O fluxes declined with increasing elevation; area-weighted flux calculations indicated that N2O emissions from premontane forest, lower montane forest, upper montane forest and montane grasslands averaged 2.23 ± 1.31, 1.68 ± 0.44, 0.44 ± 0.47 and 0.15 ± 1.10 kg N2O-N ha−1 yr−1, respectively. Soil N2O fluxes from premontane and lower montane forests exceeded prior model predictions for the region. Comprehensive investigation of field and laboratory data collected in this study suggest that soil N2O fluxes from this region were primarily driven by denitrification; that nitrate (NO3−) availability was the principal constraint on soil N2O fluxes; and that soil moisture and water-filled porosity played a secondary role in modulating N2O emissions. Any current and future changes in N management or anthropogenic N deposition may cause shifts in net soil N2O fluxes from these tropical montane ecosystems, further enhancing this emission source.

In Indonesia, the rapid expansion of oil palm and rubber plantations replaces large areas of tropical rainforest. Rainforest transformation alters the diversity and composition of parasitoid wasp communities, but appropriate management strategies to buffer their decline in rainforest transformation landscapes are not yet developed. Here, we studied the effects of rainforest conversion to smallholder rubber and oil palm plantations on parasitoid wasp species richness, abundance and species composition. We also conducted a flowering vegetation enrichment experiment using the flowering weed Asystasia gangetica in all land‐uses to investigate potential mitigation effects on parasitoid wasp diversity and composition. Rainforest transformation to rubber plantations caused a large decrease in species richness (46%) and abundance (59%) of parasitoid wasps. Community structure of parasitoid wasps differed between forest and monoculture habitats with more habitat‐specialised species in forest and a higher proportion of common species in the monoculture. The experimental flowering vegetation enrichment increased parasitoid wasp species richness by 18% and abundance by 127%. Enrichment also enhanced the presence of unique parasitoid species in plantation and furthermore increased differences in community composition between rainforest and plantations. However, the enrichment experiment was confounded by time, meaning that a multi‐year experiment with targeted controls is necessary for statistically more reliable statements. Our study shows the effect of rainforest transformation to oil palm and rubber plantations on parasitoid wasp communities. Although providing additional flowering vegetation in plantations seems to potentially mitigate diversity loss, further research is needed to confirm and to investigate the mechanisms how flowering plants alleviate negative effects of rainforest transformation on parasitoid communities. Thereby, efficient conservation strategies for parasitoids wasps and their biological control services can be developed for rapidly changing tropical landscapes.

PDF HTML阅读 XML下载 导出引用 引用提醒 博斯腾湖人工和天然芦苇湿地土壤CO2、CH4和N2O排放通量 DOI: 10.5846/stxb201610302213 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 新疆维吾尔自治区重点实验室专项基金项目（XJDX0909-2014-05）；新疆师范大学硕士研究生科技创新项目（XSY201602002） Emission fluxes of CO2, CH4, and N2O from artificial and natural reed wetlands in Bosten Lake, China Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为研究干旱区淡水湖泊人工、天然芦苇湿地土壤温室气体源汇强度及其影响因素，采用静态箱-气相色谱法，于2015年1月-12月对博斯腾湖人工和天然芦苇湿地土壤CO2、CH4和N2O通量进行全年观测。结果表明，人工芦苇湿地土壤CO2、CH4和N2O排放通量变化范围分别为：10.1-588.4mg m-2 h-1、2.9-82.4μg m-2 h-1和1.32-29.7μg m-2 h-1，天然芦苇湿地土壤CO2、CH4和N2O排放通量变化范围分别为10.3-469.6mg m-2 h-1、3.1-64.8μg m-2 h-1和1.9-14.3μg m-2 h-1。人工和天然芦苇湿地夏季土壤CO2排放通量均明显高于其他季节，而土壤CH4和N2O排放通量较大值多集中在春末夏初。全年观测期间，人工芦苇湿地土壤CO2、CH4和N2O排放通量高于天然芦苇湿地（P>0.05）；温度是影响人工、天然芦苇湿地土壤CO2和N2O排放通量的关键因素，近地面温度和5cm土壤温度与CO2和N2O排放通量呈现极显著的正相关关系（P<0.01）。土壤CH4排放通量是温度和水分二者共同影响的，由近地表温度、5cm土壤温度和土壤含水量共同拟合的方程可以分别解释人工、天然芦苇湿地土壤CH4排放通量的71%、74.5%；土壤有机碳、pH、盐分、NH4+-N、NO3--N也是人工、天然芦苇湿地土壤CO2、CH4和N2O排放通量的影响因素；人工和天然芦苇湿地土壤均是CO2、CH4和N2O的"源"。基于100年尺度，由3种温室气体计算全球增温潜势得出，人工芦苇湿地全球增温潜势大于天然芦苇湿地（15150.18kg/hm2 > 12484.21kg/hm2）。 Abstract:CO2, CH4, and N2O, have strong warming potentials and are considered to be the primary greenhouse gases in the atmosphere. Global warming caused by the increasing concentrations of atmospheric CO2, CH4, and N2O is one of the hotspots in global change field. Greenhouse gas (GHG) fluxes in reed wetlands are critical in evaluating the source/sink strength of GHG in arid area. We studied the dynamics of soil CO2, CH4, and N2O fluxes using static chamber-based on gas chromatography in two reed wetlands of the freshwater Bosten Lake, located in an arid area of Northwestern China. During a full year of monitoring, environmental variables (including soil moisture, soil temperature, air temperature, pH and salinity) were measured to determine the effects of abiotic factors on soil CO2, CH4, and N2O fluxes in artificial and natural reed wetlands. SPSS 19.0 for Windows was used to analyze the relationships between environmental factors and soil CO2, CH4, and N2O fluxes. The results showed that soil CO2, CH4, and N2O fluxes in the artificial reed wetland were 10.1-588.4mg m-2 h-1, 1.32-29.7μg m-2 h-1 and 3.1-64.8μg m-2 h-1, respectively, which was comparable with the values from the natural reed wetland. Higher soil CO2 emissions occurred in summer, whereas CH4 and N2O emissions mainly occurred in late spring and early summer. Temperature was the main factor controlling soil CO2 and N2O fluxes in both reed wetlands (P < 0.01). Soil CH4 emission flux was affected by both temperature and moisture. According to regression analysis, the combination of near-surface temperature, top 5cm soil temperature, and soil water content could explain 71% and 74.5% of soil CH4 flux in artificial and natural reed wetlands, respectively. Soil organic carbon, pH, salinity, NH4+-N, and NO3--N are also influencing factors of CO2, CH4, and N2O fluxes in artificial and natural reed wetlands. However, the differences in CO2, CH4, and N2O emissions from soils of artificial and natural reed wetlands were caused by differences in soil organic carbon, soluble nitrogen, and biomass. Based on the centennial scale, the soils of artificial and natural reed wetland were "sources" of GHG, and the global warming potential from artificial reed wetland was higher than that from natural reed wetland. 参考文献 相似文献 引证文献

Context Conversion of grasslands to croplands can usually result in the degradation of soils and increased greenhouse gas (GHG) emissions such as carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4). However, little is known about the impacts of grassland conversion to recently tilled croplands on soils and GHG fluxes. Aims A field experiment was established in 2016 to evaluate the impacts of grassland conversion to tilled cropland under different landscape positions (upslope, backslope, and footslope) on select soil properties and soil GHG fluxes. Key results The findings showed that the grassland conversion significantly increased soil bulk density and electrical conductivity but reduced pH and total nitrogen (TN). The conversion impacted soil biome community grassland and tilled croplands. The landscape position significantly impacted soil pH (footslope &lt; upslope) and TN (footslope &gt; upslope). The grassland conversion significantly decreased soil CO2 fluxes, but increased soil CH4 and N2O fluxes. The landscape position significantly impacted soil CO2 (footslope &gt; upslope and backslope) and CH4 (upslope &gt; footslope and backslope) fluxes for some periods. Soil CO2 and N2O fluxes generally followed upward and downward trends over time, respectively. Conclusions These results indicate that grassland conversion was able to lose soil N, increase soil compaction, acidity, salts, and soil N2O and CH4 fluxes, and decrease the diversity of abundant genera and CO2 fluxes. Footslope increased TN, soil acidity, CO2, and CH4 fluxes, compared with upslope and backslope. CO2 fluxes under grassland and tilled cropland significantly increased over time, whereas N2O fluxes under grassland significantly reduced. Implications Conversion of grassland to tilled cropland significantly impacted on sol quality. It caused a loss in soil N and increased soil compaction, acidity and salts. Grassland conversion also decreased the abundance and diversity soil microbiome.