Using Carbon Management Index to Assess the Impact of Compost Application on Changes in Soil Carbon after Ten Years of Rice–Wheat Cropping

Soil organic carbon (C) is a major determinant for the sustainability of agricultural systems. The changes in C pools (active or total) reflect the changes in an agricultural system. The C management index (CMI) can be used to monitor the soil over time, and it also tells whether a new system or practice is declining or rehabilitating the soil. Carbon management index was calculated for a long‐term experiment after 10 cycles of rice–wheat cropping to assess the influence of rice straw compost application either alone or in combination with inorganic fertilizers on soil C buildup. Total and labile C was greater in rice straw compost–amended soil as compared to unamended control or soils receiving inorganic fertilizers only. Application of rice straw compost increased the mean CMI (47.1) as compared to control (21.0). Labile C was positively related to mean weight diameter, and seemingly it plays an important role in the maintenance of physical fertility of soils and thus sustainability of the cropping system.     

秸秆还田对稻麦轮作农田活性有机碳组分含量、酶活性及产量的短期效应

【目的】秸秆还田作为一种有效的秸秆处理方式不仅能够提高土壤肥力,增加作物产量,还可以缓解农田生态压力。研究稻麦轮作系统下不同秸秆还田量对土壤活性有机碳库、酶活性和作物产量的短期影响,可为提出适宜当地生产的秸秆还田量提供理论依据。【方法】利用稻麦轮作农田定位试验进行了研究。采用随机区组设计,设7个处理,以稻麦季秸秆均不还田为对照处理(CK),6个不同秸秆还田量处理。测定了秸秆还田后土壤活性有机碳库和土壤酶活性的变化,稻麦产量以及三者之间的相关关系。【结果】1)与秸秆不还田处理相比,试验范围内的秸秆还田量能在一定程度上提高土壤活性碳组分的含量和土壤酶活性,并能增加水稻和小麦的产量及其构成因素;2)土壤总有机碳和微生物生物量碳的含量随着秸秆还田量增加,增幅呈先增大后减小的趋势,以连续两季50%秸秆还田量处理下显著较高,而水溶性有机碳、活性有机碳含量和碳库管理指数在连续两季25%秸秆还田量处理下最高;3)相比秸秆不还田处理,连续两季25%秸秆还田量对土壤脲酶、过氧化氢酶和蔗糖酶活性的影响均最显著;4)水稻和小麦的产量均为在连续两季25%和50%秸秆还田量处理下增产较显著,与秸秆不还田相比,水稻增产达9.0%,小麦增产达11.45%;5)土壤碳库、土壤酶活性以及水稻和小麦产量之间均存在显著相关。【结论】在本试验条件下,连续两季25%和50%秸秆还田量表现出显著提高土壤碳汇能力和增加作物产量的优势。     

秸秆还田对汉中盆地稻田土壤有机碳组分、碳储量及水稻产量的影响

为探索稻麦或稻油轮作制下,小麦、油菜秸秆还田对汉中盆地稻田土壤碳库组分的变化,设置小麦秸秆不还田(WSN)、小麦秸秆常规还田(WS)、小麦秸秆促腐还田(WSM)、油菜秸秆不还田(RSN)、油菜秸秆常规还田(RS)、油菜秸秆促腐还田(RSM),共6个处理,通过大田试验研究了不同秸秆类型及还田方式对稻田0—5,5—10,10—15,15—20,20—25cm 5个土壤层次中的土壤容重、总有机碳(TOC)、活性有机碳(LOC)、活性有机碳效率(ACL)、碳储量(SCS)、碳库管理指数(CPMI)及水稻产量的影响。结果表明:秸秆还田显著降低0—15cm土层容重,对15—25cm并未产生显著影响。与不还田相比,秸秆还田明显增加了各层次土壤有机碳库指标含量,但TOC和LOC含量均随土壤深度的增加而减少,两者在0—15cm土层含量较高,具有明显的表层富集现象;与不还田相比,小麦及油菜秸秆还田后可明显增加稻田0—25cm土层中的土壤碳储量(SCS),增幅可达21.9%~23.5%和1.7%~6.7%。不同土层中的LOC、ACL、CPIM对秸秆类型的响应不同,具体表现为小麦秸秆还田(WS、WSM)对0—15cm土层具有显著促进作用,而油菜秸秆还田(RS、RSM)对15—25cm土层中的有显著促进作用。产量方面,秸秆促腐还田模式下(WSM、RSM)水稻产量最高,常规还田模式(WSN、RSN)次之,而不还田时产量最低。相关分析显示0—10cm土壤活性有机碳有效率与水稻产量显著相关。秸秆还田是提高汉中盆地稻田土壤有机碳和产量较为有效的农田管理措施。两种轮作模式下,小麦秸秆全量旋耕还田更有利于固持稻田土壤有机碳和增加水稻产量增加。     

稻草还田条件下水田和旱地土壤有机碳矿化特征与差异

采用14C示踪技术,通过100 d的原状土柱室内模拟试验,得出以下研究结果:培养100 d后,有34.74%(水田覆盖)、17.85%(水田翻埋)、35.68%(旱地覆盖)和36.06%(旱地翻埋)的稻草碳被矿化,水田和旱地土壤分别有0.99%～1.17%和2.25%～2.53%的原有有机碳被矿化。土地利用和稻草还田方式及两因素的交互作用,对添加稻草碳的矿化速率和累积矿化率均有显著影响(p<0.01),但对于土壤原有有机碳的矿化速率和累积矿化量,只有土地利用方式对其有显著影响(p<0.01);添加稻草后,土壤总累积矿化量没有发生显著变化(旱地翻埋除外),因为稻草还田抑制了土壤原有有机碳的降解,使100 d的累积矿化量相对于各自对照减少了13.95%(水田覆盖)、15.68%(水田翻埋)、11.04%(旱地覆盖)和3.34%(旱地翻埋)。水田翻埋和旱地覆盖是稻草资源合理利用的较好方式,更有利于土壤有机碳的积累;添加的稻草碳和土壤原有有机碳在水田的矿化速率均显著低于旱地,是水田有机碳含量通常高于同一景观单元旱地的主要原因之一。     

秸秆还田提高水稻-油菜轮作土壤固氮能力及作物产量

为探讨西南山区水稻-油菜轮作模式下秸秆还田对作物产量和土壤氮素固持能力的影响,于2013-2015年在洱海流域稻油轮作农田中设置空白处理(CK)、单施化肥(CF)、化肥+玉米秸秆(CFMS)以及化肥+蚕豆秸秆(CFBS)4个处理,测定分析了作物产量、土壤微生物量及土壤理化性质等关键指标。结果表明,与CF处理相比,秸秆还田提高水稻、油菜产量及其地上部含氮量,增加氮素有效输出。不同处理土壤微生物量碳、氮质量分数存在差异,其大小顺序为:CFMSCFBSCFCK。与土壤碳氮比相比,土壤微生物熵和微生物量C/N对秸秆还田做出快速响应,秸秆还田提高土壤微生物熵,降低微生物量C/N。此外,秸秆还田显著降低油菜收获后的土壤硝态氮残留(P0.05),与CF相比,玉米秸秆和蚕豆秸秆还田分别使土壤硝态氮残留量减少11.6%~55.0%和13.7%~52.3%。可见,中国西南山区稻油轮作模式下秸秆还田能提高作物产量和含氮量,增强土壤微生物氮素固持能力,有效降低土壤氮素流失风险,且玉米秸秆在增产、固氮方面的作用优于蚕豆秸秆。结果可为提高西南山区水稻、油菜产量,增强土壤氮素固持能力,降低土壤氮素流失风险提供参考。     

高效木质纤维素分解菌群筛选及其酸碱调节能力研究

为获得能够改良土壤酸碱性的微生物群体, 以混合堆放牛粪、鸡粪的储粪池外围土样为材料, 采用限制培养技术筛选了一组木质纤维素分解菌群, 并对该菌群在不同初始pH下的适应能力和纤维材料的分解能力及其耐盐特性进行了研究。结果表明: 以不同碳源(滤纸、玉米秸秆、稻草秸秆和小麦秸秆)制作不同初始pH(5.0~11.0)的培养基, 接种木质纤维素分解菌群后培养基pH均迅速向中性变化, 第3 d集中至8.0左右, 6 d后稳定至7.8~8.6; 7 d内滤纸、玉米秸秆、稻草秸秆和小麦秸秆失重率分别超过93.15%、50.53%、44.29%和42.60%; 以滤纸为惟一碳源、NaCl浓度2.0%的培养基接种, 7 d滤纸失重率达84.82%。木质纤维素分解菌群具有较强的适应及调节pH能力, 且能够高效分解木质纤维材料, 并具有一定的耐盐特性, 可见该菌群在酸碱土壤酸碱性改良领域具有一定开发潜力。     

稻麦秸秆全量还田的产量与环境效应及其调控

秸秆还田是一项土壤培肥、实现农业可持续发展的重要措施,但稻秆还田经济效益低、增产效应不显著以及一些环境负效应,影响了该措施的推广。本文结合本课题组研究工作,综述了国内外近期的相关研究进展,就稻麦秸秆全量还田的产量效应、秸秆腐解特性与环境效应及其调控进行了分析。研究表明,秸秆还田能提高土壤肥力,增加稻麦产量,且增产效应随还田时间延长而增加;稻季麦秸/油菜秸的腐解率在50%~66%,其N、P、K养分释放率分别为42%~58%、55%~68%和92%~98%;秸秆还田能显著提高农田碳固定、减少径流损失,但也增加了稻田甲烷排放、氨挥发以及渗漏的养分损失。提高秸秆还田效益的调控措施有:增加稻麦前期氮肥施用比例,适当减少总的氮肥、磷肥用量,大幅减少钾肥用量;秸秆尽量在麦季还田、稻季采用湿润灌溉可减少甲烷排放。     

Improved and sustainable agroecosystem,food security and environmental resilience through zero tillage with emphasis on soils of temperate and subtropical climate regions: A review

Tillage is one of the agricultural management practices that significantly impacts agroecosystems, crop production, and the environment. Conventional tillage (CT) practices alter the soil environment and induce organic constituents’ decomposition and the emission of greenhouse gases (GHGs), which contribute to the greenhouse effect and global warming. Low organic matter, biological diversity, aggregate stability, high erosion and degradation of the soil environment, and sequestration strength are additional factors associated with CT, which negatively affect food security and environmental sustainability. As a result, CT is no more beneficial in the long run; consequently, zero tillage (ZT) could be a viable candidate for sustainable agriculture. The review to establish this systematically compared and summarized the effect of tillage systems (i.e. CT and ZT) by synthesizing and interpreting published data (>150 peer-reviewed articles) with >200 observations on soil ecosystem services and properties/agroecosystem, crop yield/food security, GHG emission, and carbon sequestration/environmental resilience. The review established that ZT improves soil structure, aggregate stability, biological diversity, organic matter and nutrients, water and water use efficiency, and reduces soil degradation, erosion, tillage machinery impacts, and GHG emissions. It allows timely seeding and better crop growth, increases yield and food security, improves carbon sequestration, strengthens soil storage potential, and helps to mitigate the adverse effects of climate change on environmental resilience. Based on various latent direct and indirect benefits, resource-saving ability, and broad adoption scope of ZT, it is corroborated that ZT is a practical and potential approach for improved and sustainable agroecosystem, food security, and environmental resilience.     

可持续的中国农业养分管理: 挑战与展望

China has to raise agricultural productivity in its limited and shrinking farmland to guarantee food security for its huge and ever-growing population. Sustainable soil nutrient management is of paramount importance to the world's most populous country. Critical challenges the country is facing in sustaining soil fertility and in alleviating the hazardous impact of intensive fertilizer use are discussed in this paper. It is emphatically pointed out that national strategies as well as area-specific action plans with respect to scientific nutrient management are urgently needed to balance productivity and sustainability in the future. Relevant proposals for addressing those challenges are also presented.     

Soil carbon budget in a single-cropping paddy field with rice straw application and water management based on soil redox potential

Abstract

An ideal state for agroecosystems to mitigate global warming should include both decreasing CO₂ and CH₄ emissions and increasing soil carbon storage. Two-year field experiments were carried out to examine the effects of water management (continuous flooding [CF] and Eh control [EH]) and rice straw management (application [+S] and removal [–S]) on the soil carbon budget in a single-cropping paddy field in Japan. The EH water management based on soil redox potential that the authors have proposed decreased the total CH₄ emission during the rice growing period compared with CF. The +S increased CO₂ emission as soil respiration during the non-flooded fallow period compared with –S, but also increased straw residues in the soil. However, there was little evidence for sequential carbon accumulation in the soil over the year by +S. The resultant annual budget of soil carbon was a loss of 32–103 g C m^?2 in the EH+S treatment compared with a loss of 166–188 g C m^?2 in the CF–S treatment. Taking into account the global warming potentials, the EH+S treatment also decreased the total CO₂-equivalent emission compared with the CF–S treatment. Consequently, a combination of appropriate water management and straw application will be an effective option in decreasing both CO₂-equivalent emission and sustaining soil carbon storage.     

环境与人为因子对水稻土有机质变化的影响——以长江中下游平原为例

Changes in soil organic matter (SOM) can affect food security,soil and water conservation,and climate change.However,the drivers of changes in SOM in paddy soils of China are not fully understood because the effects of agricultural management and environmental factors are studied separately.Soil,climate,terrain,and agricultural management data from 6 counties selected based on representative soil types and cropping systems in China were used in correlation analysis,analysis of variance,and cforest modeling to analyze the drivers of changes in SOM in paddy soils in the Middle and Lower Yangtze River Plain from 1980 to 2011.The aims of this study were to identify the main factors driving the changes in SOM and to quantitatively evaluate their individual impacts.Results showed that the paddy SOM stock in the study area increased by 12.5％ at an average rate of 0.023 kg m-2 year-1 over the 31-year study period.As a result of long-term rice planting,agricultural management practices had a greater influence than soil properties,climate,and terrain.Among the major drivers,straw incorporation,the most influential driver,together with fertilization and tillage practices,significantly increased the accumulation of SOM,while an increase in temperature significantly influenced SOM decomposition.Therefore,to confront the challenge of rising temperatures,it is important to strengthen the positive effects of agricultural management.Rational fertilizer use for stabilizing grain production and crop straw incorporation are promising measures for potential carbon sequestration in this region.     

Incorporation of C-labeled rice-straw-derived carbon into microbial communities in submerged rice field soil and percolating water

Rice straw is a major organic material applied to rice fields. The microorganisms growing on rice-straw-derived carbon have not been well studied. Here, we applied ¹³C-labeled rice straw to submerged rice soil microcosms and analyzed phospholipid fatty acids (PLFAs) in the soil and percolating water to trace the assimilation of rice-straw-derived carbon into microorganisms. PLFAs in the soil and water were markedly enriched with ¹³C during the first 3 days of incubation, which indicated immediate incorporation of rice-straw-derived carbon into microbial biomass. The enrichment of PLFAs in the percolating water with ¹³C suggested that microorganisms other than the population colonizing rice straw also assimilated rice-straw-derived carbon or that some bacterial groups were selectively released from the straw. The microbial populations could be categorized into two communities based on the carbon isotope data of the PLFAs: those derived from rice straw and those derived from soil organic matter (SOM). The composition of the PLFAs from the two communities differed, which indicated the assimilation of rice-straw-derived carbon by a subset of microbial populations. The composition of rice-straw-derived PLFAs in the percolating water was also distinct from that in the soil.     

Potential and promisingness of technical options for mitigating greenhouse gas emissions from rice cultivation in Southeast Asian countries

ABSTRACT

Paddy fields are considered as one of the most important sources of anthropogenic methane (CH₄) and nitrous oxide (N₂O) emissions. While several technical options have been proposed to reduce these emissions, gaps in data and information based on application of these options in the field are a key barrier to scaling-up. To address these gaps, we conducted a review of literature to analyze the potential of technical options in Southeast Asia (SEA). Using screening criteria based on reliability of experimental data, 31 region-specific cases were selected for the analysis. A meta-analysis indicated that water management options, including single and multiple drainage approaches such as alternative wetting and drying (AWD), significantly reduced CH₄ emissions by 35% as a mean effect size (95% confidential interval: 41–29%), as well as the combined effects of CH₄+N₂O (net GWP) by 29% (36–23%). The effect on reducing CH₄ emissions in the dry season was significantly larger than that in the wet season. Application of biochar reduced both CH₄ and N₂O emissions by 20% (40% to ?7%), while significantly increased rice yield by 28% (8–52%). Other options such as removal of rice straw from the previous crop, composting rice straw and manure, application of sulfate-containing fertilizer, and soil drying in the fallow season also have recognized potential to reduce emissions but require further data and consideration of possible trade-offs. Based on the analysis of mitigation potential, promising technical options were assessed by considering together with constraints and additional co-benefits in order to provide a useful guide for policy makers and rice value chain operators in SEA countries for adopting mitigation options in rice cultivation to tackle climate change and enhance agriculture sector sustainability.     

秸秆还田对土壤还原性和水稻根系生长及产量的影响

为明确油菜秸秆还田对土壤环境及水稻根系生长的影响,该研究采用田间试验与栽培模拟试验相结合的方法,分析了油菜秸秆还田后,稻田土壤氧化还原电位(EH值)、还原性物质总量和Fe2+含量的变化规律及水稻苗期根系数量、质量、体积、长度和伤流强度等的变化规律。结果表明,1)油菜秸秆覆盖或翻埋条件下,稻田土壤氧化还原电位日均变化量(RCEH值)表现为先降低后增加的趋势,而土壤还原性物质总量日均变化量(RCRRM值)和土壤二价铁含量日均变化量(RCFe值)表现为先增加后降低的趋势;其中水稻移栽后14~18 d土壤RCEH值最低,移栽后10~14 d和14~22 d土壤RCRRM值(0.28~0.62 cmol/(kg·d))和RCFe值(5.0~31.6μg/(kg·d))达到最大。2)油菜秸秆覆盖或翻埋条件下,随着秸秆还田量的增加,水稻根系总量(数量、质量、体积和长度)、白根数量和根系伤流强度显著降低;与覆盖相比,油菜秸秆翻埋对水稻根系伤流日均变化量(RC_(RBI))的影响时间更长,水稻根系体积日均变化量(RCRVT值)和质量日均变化量(RCRQT值)的缓慢增长期延长了4 d。3)水稻移栽后10~22 d,油菜秸秆还田对稻田土壤环境和水稻根系生长的影响最显著;移栽后27~32 d,油菜秸秆还田对水稻根系生长的影响程度显著降低。油菜秸秆还田条件下,随着秸秆还田量增加,水稻苗期的土壤氧化还原电位显著降低,土壤还原性物质总量和Fe2+含量显著增加;水稻根系总量(数量、质量、体积和长度)和根系活力(白根数量和根系伤流强度)显著降低。在四川油稻两熟区,油菜秸秆还田量以全量还田为宜,适宜机械作业的田块以油菜秸秆翻埋还田为宜。     

秸秆还田及氮肥调控对不同肥力白浆土氮素及水稻产量影响

三江平原是黑龙江省水稻主要种植区,白浆土是主要种稻土壤,在白浆土上开展秸秆还田试验研究,明确白浆土秸秆还田效果,根据土壤肥力水平调控氮素为秸秆还田提出因地制宜的土壤、施肥等管理技术提供参考。该文以白浆土为供试土壤,比较研究不同肥力白浆土上连续秸秆还田及调控氮素对水稻产量及土壤养分变化的影响。结果得出:高肥力土壤连续秸秆还田适合减氮,减氮10%连续3年水稻不减产,增产幅度为0.1%～6.94%,减氮20%以上产量降低,秸秆连续还田增加氮素水稻产量第1年与正常施肥比增产4.47%,第2年水稻产量比对照减产4.02%～31.86%,调氮降低幅度大;中、低肥力土壤秸秆还田水稻产量第1年比对照分别增加1.48%,4.52%,第2年调氮增产幅度会下降;秸秆还田使土壤有机质、氮素含量提高,在高肥力土壤上氮素过高使水稻前期分蘖量增多,水稻有效穗数降低,产量降低,减氮后可以避免土壤氮素过剩,水稻产量提高;中、低肥力土壤秸秆还田有利于增加土壤肥力水平,适当增加氮素可使水稻产量提高。     

施用稻草对酸性红壤活性铝的动态影响

酸性红壤区土壤活性铝含量的变化,对作物生长有重要影响。通过室内培养试验研究了施用不等量稻草对酸性红壤水溶性有机碳、pH值和土壤交换性铝和有机络合态铝的动态变化。结果表明,土壤水溶性有机碳在第一天达到最大值,之后开始下降直至趋于平衡。土壤pH值在前10天内快速提高,添加的稻草量越大,提高的幅度也越大,之后缓慢下降至第30天渐趋平衡;土壤交换性铝则是先降低,10天后逐渐增加至稳定状态。有机络合态铝在可溶性有机碳和有机酸等小分子化合物的联合作用下,先增加而后降低。在稻草分解的前10天,土壤水溶性碳、小分子化合物和土壤pH值对铝形态的影响均较大,而到实验后期,土壤pH值发挥着主导作用。     

轮作模式及秸秆还田对水稻产量、稻米品质及土壤肥力的影响

  【目的】  研究不同水旱轮作模式下秸秆还田对水稻产量、土壤养分和稻米品质的影响,为多元化轮作模式秸秆还田和水稻提质丰产提供科学依据。  【方法】  田间试验于2018—2020年在陕西省汉中市农业科学研究所韩塘试验基地进行。试验包含轮作模式和秸秆还田2个处理因素,采用随机区组设计,共设油菜–水稻(R–R)、绿肥(紫云英)–水稻(G–R)、冬闲–水稻(W–R) 3种轮作模式,每种轮作模式设秸秆不还田和秸秆还田,共6个处理。水稻收获后,测定了水稻产量和产量构成因素,以及0—20 cm土壤养分含量。  【结果】  轮作模式和秸秆还田对土壤养分影响显著,轮作模式的培肥效果表现为R–R>W–R>G–R。同一轮作模式下,与秸秆不还田相比,秸秆还田处理的土壤活性有机碳、有机碳、碱解氮、速效磷、速效钾含量两年平均增幅分别为4.09%～18.89%、6.84%～24.06%、9.63%～17.43%、9.10%～41.05%、3.72%～17.36%。轮作模式对供试品种穗粒数影响显著,秸秆还田则对穗粒数和有效穗影响显著。轮作模式对水稻产量影响显著,而秸秆还田对产量无显著影响。R–R模式下‘荃香优1521’产量分别较G–R和W–R增产1.71%和8.95%,‘黄华占’产量分别较G–R和W–R增产5.51%和6.41%。轮作模式对稻米外观品质影响不显著,对整精米率、蛋白质、直链淀粉含量和食味值影响显著。G–R模式较R–R和W–R显著增加蛋白质含量,降低直链淀粉含量,增加胶稠度,平均增幅分别为11.01%、?2.56%、4.69%。与秸秆不还田相比,秸秆还田显著增加了整精米率和食味值,增幅分别为0.48%～3.12%和0.45%～4.79%。  【结论】  油菜–水稻、绿肥(紫云英)–水稻、冬闲–水稻3种模式下,周年秸秆全量还田可以提高土壤肥力,增加水稻穗粒数和有效穗,提高水稻产量,改善稻米外观品质和加工品质、提高营养品质和蒸食品质。绿肥(紫云英)–水稻轮作改善稻米品质的优势明显,因此,绿肥(紫云英)–水稻轮作结合稻草周年全量还田是一种适合汉中地区农业高质量发展的绿色栽培模式。     

稻草还田下非稻季持续淹水对稻季CH_4和CO_2排放的影响

稻草还田和非稻季持续淹水是我国最重要的稻田管理方式之一,此种管理方式下稻田碳排放并不清楚。本研究以江汉平原中稻-冬闲制度为对象,探讨稻草还田耦合非稻季持续淹水对稻季碳排放的影响,为准确评估稻田温室气体排放提供数据支撑和理论支持。结果表明,在稻草秸秆全量覆盖还田下,非稻季自然排水比持续淹水显著降低稻季CH_4累积排放量,稻季第一次排水晒田之前CH_4排放占总排放量的80%以上;非稻季持续淹水使稻季CO_2累积排放量比自然排水稍有降低,CO_2排放主要集中在第一次排水晒田之后,占总排放量的60%左右。非稻季淹水降低稻季土壤NO_3~--N、NH_4~+-N和DOC浓度以及10 cm土层土壤Eh值,但使乙酸浓度升高,这可能是稻草还田耦合非稻季淹水导致CH_4排放量增加的主要原因。     

Estimation of the Effects of Maize Straw Return on Soil Carbon and Nutrients Using Response Surface Methodology

Straw incorporation is generally considered an effective agricultural management practice that improves nutrient cycling and maintains soil fertility. To study the interactive effects of straw returning factors on soil organic carbon and available nutrients, a17-month(May 6, 2016 to October 6, 2017) experiment was conducted on straw incorporation by using response surface methodology under a three-factor(straw length, amount, and burying depth), five-level quadratic orthogonal rotation experimental design. Weight was assigned to each indicator for soil carbon and nutrients and then a comprehensive indicator was established. Then, a second-order polynomial model of the three straw returning factors was established using response surface methodology. Results indicated that17 months after straw incorporation, straw amount and burying depth had significant effects on the comprehensive indicator of soil carbon and nutrients. Straw length and the interactions of straw amount and burying depth showed no significant effects on the comprehensive indicator of soil carbon and nutrients. It was concluded that 17 months after straw incorporation, the highest value of the comprehensive indicator of soil carbon and nutrients was achieved when the straw length, amount, and burying depth were approximately 17–20 cm, 740–840 g m~(-2), and 9–13 cm, respectively, which can be recommended as the most suitable parameters for use in straw returning in the study area.     

稻草覆盖和香根草篱联合调控红壤坡耕地土壤团聚体粒组碳钾分配规律

土壤有机碳可以通过影响土壤矿物钾释放以及解钾菌特性而对土壤钾素产生影响,本文基于稻草覆盖和香根草篱控制红壤坡耕地水土流失长期定位试验,通过对比常规管理(CK)、稻草覆盖(S)、稻草覆盖+香根草篱(S+V)处理,研究稻草覆盖及香根草篱措施对土壤主要化学性质的影响,并分析土壤团聚体粒组分布及碳和钾在土壤团聚体粒组中的分配规律。结果表明,在所有处理中,S+V处理的土壤pH、有机碳、全钾和速效钾含量显著较高,与CK处理相比,S+V处理的土壤pH提高了0.23,有机碳、全钾和速效钾含量分别提高了6.52%、11.60%和11.49%。不同处理下土壤团聚体粒组分布无显著差异,所有土壤团聚体粒组中均以>0.25 mm土壤团聚体粒组的比例最高。与CK处理相比,S和S+V处理的>2 mm土壤团聚体粒组有机碳含量分别提高了9.42%和40.03%。与CK处理相比,S+V处理下>2 mm、0.25～0.053 mm和<0.053 mm土壤团聚体粒组中全钾含量分别提高了3.67%、4.92%和5.14%。同时,S+V处理下>2 mm和<0.053 mm土壤团聚体粒组中速效钾...