Northeast China's croplands harbor critical soil organic carbon (SOC) reserves essential for soil fertility and food security. Partitioning SOC into particulate (POC) and mineral-associated organic carbon (MAOC) fractions advances mechanistic understanding of C cycling and enables targeted sequestration strategies. To resolve the unresolved latitudinal patterns and controls of these fractions, we analyzed 96 cropland soils spanning 40.03°-48.02° N at 0-20 cm and 20-40 cm depths. SOC and MAOC stocks increased markedly with latitude across both soil layers, whereas POC stock exhibited no visible spatial trend. Though both fractions correlated significantly with total SOC, POC stock demonstrated greater sensitivity to SOC stock changes than MAOC stock. Multivariate analyses revealed divergent drivers: 35-38 % of SOC and MAOC stocks variation in topsoil (and 27-31 % in subsoil) stemmed from interactions among climate, soil properties, and enzyme activity, whereas POC stock variation was dominated by soil properties (46 %) in topsoil and enzyme activity (28 %) in deeper strata. Random forest modeling identified mean annual temperature as the primary driver for topsoil SOC and MAOC stocks and total N for subsoil dynamics. Our findings establish temperature sensitivity and nitrogen availability as pivotal controls over SOC fraction distribution, providing actionable strategies for C management in temperate croplands under changing climates.

Horqin Sandy Land suffers from desertification, drought, and low fertility, limiting soybean production. Agrivoltaics provides a promising integrated model; however, the effects of agrivoltaics combined with water–fertilizer management on crop productivity remain unclear. A 2-year field experiment was conducted in a semi-arid area with three treatments, open-field control (Open), shaded area under panels (Under), and light-exposed area inter-panels (Gap). Results showed that photovoltaic systems combined with integrated water–fertilizer management improved soybean yield, soil water, and nutrient conditions. Soybean grain yield was 60.7% and 38.2% higher in the Gap and Under treatments, respectively, than in the Open. The highest yield in the Gap treatment resulted from both enhanced photosynthesis and improved root development. The Under endured light stress but exhibited morphological plasticity (plant height and leaf area increased by 43.1%, 48.2%), and shading alleviated water stress since soil water content was increased by 81.6–119.0% during growing seasons, transpiration rate (Tr) decreased by 55.1%, and leaf water use efficiency (WUE) increased by 48.8%. The Open suffered from soil degradation and water and fertilizer loss, resulting in severely limited yield. Agrivoltaics increased net income by 1466 CNY·ha−1 and improved soil nutrients, demonstrating economic and ecological benefits. Thus, it is a suitable technical model for semi-arid sandy regions.

[Objective]This study aimed to explore the effects of different straw return methods on the distribution and stability of soil aggregates,as well as the organic carbon components and carbon sequestration effect in meadow soil,so as to provide the theoretical and practical basis for improving soil aggregate structure and enhancing carbon sequestration potential.[Method]Based on an 11-year long-term field experiment,the treatments were no straw returning(CK),full no-tillage with straw mulching(SNT),half no-tillage with straw mulching(NT),full annual incorporation of straw(S1),and full biennial incorporation of straw(S2).[Result]Compared with the CK treatment,the SNT treatment significantly increased soil organic carbon content in the 0-40 cm soil layer by 2.5%to 6.6%.Straw returning could increase the content of active carbon components(easily oxidized organic carbon and microbial biomass carbon)in the 0-40 cm soil layer to varying degrees.Among them,the S1 treatment significantly increased the easily oxidized organic carbon content in the 0-40 cm soil layer from 15.4%to 20.1%,and the NT treatment significantly increased the microbial biomass carbon content in the 0-40 cm soil layer from16.0%to 17.6%.The SNT treatment significantly increased the easily oxidized organic carbon and microbial biomass carbon content in the 0-40 cm soil layer,with increases of 53.6%to 54.1%and 34.6%to 57.2%,respectively.Compared with the CK treatment,the S2 treatment significantly increased the percentage of water-stable macroaggregates(>0.25 mm)in the 0-20 cm soil layer and improved the distribution of aggregates of different sizes.The content of 3-5 mm and 0.5-1 mm aggregates increased significantly by 16.8%and 49.0%,respectively.The S1 treatment and NT treatment significantly increased the percentage of water-stable macroaggregates(>0.25 mm)in the 20-40 cm soil layer.The content of>5 mm aggregates in the S1 treatment increased significantly by 10.3%,and the content of 3-5 mm aggregates in the NT treatment increased significantly by 25.7%.The content of easily oxidized organic carbon in the surface soil was significantly positively correlated with the percentage of>0.25 mm macroaggregates.The effects of different straw returning methods on the content of easily oxidizable organic carbon in each particle size aggregate were different.The SNT treatment and the S1 treatment significantly increased the content of easily oxidizable organic carbon in each particle size aggregate.Among them,the SNT treatment increased the content by 9.5%-15.9%in the 0-20 cm soil layer and by 9.1%-23.9%in the 20-40 cm soil layer,while the S1 treatment increased the content by 12.7%-23.2%in the 0-20 cm soil layer and by 14.8%-19.4%in the 20-40 cm soil layer.[Conclusion]Different straw returning methods could increase the soil organic carbon content and the content of active carbon components in the 0-40 cm soil layer to varying degrees,and improve the distribution of aggregate size classes.Among them,full amount no-tillage and straw mulching returning was more conducive to increasing soil organic carbon,easily oxidized organic carbon and microbial biomass carbon content,and promoting the formation of easily oxidized organic carbon in aggregates to enhance soil carbon sequestration potential.

Excessive maize canopy dominance can restrict peanut performance in maize/peanut strip intercropping, but the long-term effects of regulating maize canopy structure on component-crop light use and system productivity remain unclear. This study evaluated whether EDAH-mediated regulation of maize canopy dominance could alter crop light interception (LI), improve light use efficiency (LUE), and enhance system productivity. A five-year field experiment (2020-2024) was conducted in Liaoning Province, China, with sole maize, sole peanut, and maize/peanut strip intercropping treatments. Maize canopy regulation was achieved by applying a compound plant growth regulator (EDAH; 27% ethephon and 3% diethyl aminoethyl hexanoate) to maize at the V7 stage. Light interception was estimated using a strip-intercropping light interception model. Across five growing seasons, EDAH reduced the maximum plant height and leaf area index of intercropped maize by 7.9% and 14.7%, respectively, resulting in a more compact maize canopy. This canopy adjustment slightly increased peanut LI by 5.2% and reduced maize LI by 5.4%, relative to the non-sprayed intercrop, although neither difference was statistically significant. Meanwhile, canopy regulation increased dry matter-based and grain-based LUE of intercropped peanut by 18.0% and 12.0%, respectively, and increased grain-based LUE of intercropped maize by 17.8%. These responses were accompanied by yield increases of 10.1% for intercropped maize and 21.9% for intercropped peanut. For 2020-2023, EDAH increased the land equivalent ratio (LER) by 11.9% relative to the untreated intercrop. The results indicate that EDAH-mediated canopy regulation improved component-crop LUE and system productivity, while the modeled LI responses suggest that changes in crop light distribution may contribute to these benefits. These findings show that regulating maize canopy dominance can improve maize/peanut strip intercropping productivity by modifying canopy structure and balancing competition and complementarity between component crops.

Soil salinization is a global constraint that hampers agricultural production; rice, a key cash crop, is also vulnerable to its adverse effects. Straw returning enhances soil fertility and is considered as an effective strategy for improving saline soil quality. However, it is unclear how the effects of straw returning on rice root development and soil phosphorus (P) utilize in coastal saline-alkali soils. This study was conducted in a continuous six-year experimental field for straw returning. In the sixth year, “Yan Feng 47” rice was used to assess root characteristics and physiological and biochemical responses related to rice yield and P use efficiency under straw returning in coastal saline-alkali soils. Metagenomic sequencing methods were used to examine changes in soil microbial diversity following straw returning (S). Under S treatment, root biomass, length, diameter, and volume significantly increased by 37.4%, 24.0%, 12.8%, and 9.5%, respectively. Acid phosphatase (APase) activity, malic acid, and citric acid levels in rice roots significantly increased by 37.6%, 56.1%, and 1.3-fold, respectively. APase activity and available P in the rhizosphere soil significantly increased by 72.0% and 34.8%. Inorganic phosphorus (Pi) uptake of roots and yield increased by 29.6% and 35.7%. Straw returning can effectively improve the coastal saline-alkali soils and improves the abundance of microorganisms that promotes the degradation of straw and the hydrolysis of organic phosphorus. The application of straw returning positively influenced rice root development, microorganisms activity, Pi uptake, and grain yield.

Shading from taller cereal plants often reduces the growth of shorter, intercropped legumes and the productivity of cereal-legume intercropping systems. To mitigate the effect of shade on companion crops, pruning (leaf cutting) maize plants at a seedling stage is an increasingly common practice. However, it is not clear if this leaf-removal strategy benefits leguminous crop yield without causing a loss in cereal crop yield. A 2-year field experiment was performed to investigate the impact of cutting maize leaves at V4 stage (TV4) and V5 stage (TV5) on the growth and yield of intercropped peanuts. Across 2 years, peanut yield was 22.9% higher in TV4 and 33.5% higher in TV5 treatments than it was in a nonleaf-cutting control, whereas maize grain yield was not affected, with a slight increase in TV4 and a slight decrease in TV5. Compared with uncut controls, maize plant height was reduced by 30.2 cm (23.9%) in the TV4 treatment and 49.2 cm (35.5%) in the TV5 treatment, whereas photosynthetically active radiation reaching peanuts strips increased by 16.6% and 22.8%, respectively; the net photosynthetic rates of peanuts increased by 17.4% on average. Seedling leaf cutting shortened maize roots but increased peanut root length (28.6%) and surface area (30.8%) over time. The positive effects of seedling leaf cutting contributed to an increase in nitrogen absorption by 26.6% and 20.8% greater total biomass of peanuts. Cutting leaves at stage V4 resulted in a greater intercropping-system land equivalent ratio than cutting them at the V5 stage, whereas leaf cutting at the V5 stage contributes to a greater increase in the intercropped peanut yield. We demonstrate that cutting leaves of intercropped maize at the seedling stage improves peanut yield by optimizing the canopy light environment and modifying belowground root development of peanuts.

The plant growth regulator EDAH, a combination of ethephon and diethyl aminoethyl hexanoate, has been shown to reduce maize lodging and increase crop yield under monoculture systems. However, its effectiveness under intercropping conditions remains uncertain. This study presents findings from a three-year (2020–2022) experiment that investigated the effects of EDAH application on maize and peanut yields, as well as lodging rates, within a maize/peanut intercropping system. The experimental setup included four treatments: sole maize without EDAH, sole peanut without EDAH, intercropped maize and peanut without EDAH, and intercropped maize and peanut with EDAH. Results across the three years revealed that foliar application of EDAH significantly increased maize yield by 13.6% and peanut yield by 28.3%, compared to the non-EDAH treatment in the intercropping system. Moreover, the land-equivalent ratio improved by 13.4%, indicating better land use efficiency. Maize lodging in the intercropping system with EDAH decreased by 48.7%. Additionally, EDAH-treated maize in the intercropping system exhibited a 12.1% reduction in plant height and a 27.7% reduction in ear height compared to untreated maize. The internodes 1–5 of EDAH-treated intercropped maize were 1.93–7.80 cm shorter, while the basal internode diameter increased by 3.30 to 4.90 cm. These morphological changes contributed to improved stalk strength, as evidenced by increases in stalk crush strength, rind penetration strength, and bending strength, which together improved maize lodging resistance. Collectively, these results suggest that the application of EDAH is a promising measure to reduce maize lodging and increase overall crop productivity in maize/peanut intercropping systems.

为探讨水稻氮肥阈值周年间变化及其影响因素,科学制定化肥减施策略,通过8年的田间定位试验,利用线性加平台肥料效应函数分析水稻目标产量下的氮肥阈值周年变化及其影响因素.结果表明,试验区水稻目标产量为9860～10 019kg/hm2,氮肥阈值为205.02～220.61kg/hm2,基于稻田氮素表观平衡的目标产量氮肥阈值周年变化最大幅度为7.60％,其直接影响因素表现为土壤无机氮含量＞植株吸氮量＞灌溉输入无机氮含量,间接影响因素是降雨携带无机氮含量.

间作系统因其产量优势及生态功能在全世界都广泛应用,尤其是禾本科与豆科作物的优势组合,但该间作体系中作物根系互作对碳代谢特性的影响尚不明确.通过2年田间试验结合盆栽模拟根系分隔(根系无互作;根系部分互作;根系完全互作)方法,采用Biolog技术研究了不同种植模式对谷子和花生籽粒产量、土地生产力及土壤微生物碳源利用特征的影响.2017～2018年田间试验结果表明,2种间作模式下土地当量比(LER)均大于1,尤其是谷子-花生2∶2模式LER于2018年达到1.36,表明禾本科作物谷子与豆科作物花生体系是具有产量优势的间作系统.室内盆栽研究结果表明,间作模式下谷子的生物量与产量分别增加了49.0％和92.6％,花生则增加了11.1％和44.6％,谷子与花生的收获指数(HI)也显著增加.与完全分隔无根系互作相比,根系互作促进了根际微生物碳源利用效率,谷子与花生根际微生物对31种碳源平均利用率分别增加了19.6％和72.2％.土壤微生物对6大碳源种类的平均利用以糖类和氨基酸类为主,对酚酸类利用率最低.主成分分析结果表明,间作与部分间作花生对根际土壤碳源利用率显著高于谷子与花生单作,而单作花生对碳源利用率最低.Shannon指数和Simpson指数研究结果表明,间作提高了土壤群落微生物多样性和均匀度.禾本科作物谷子与豆科作物花生间作体系通过根系互作提高了生物量积累,促进了地下部根际微生物对底物碳源利用,增强了微生物群落结构多样性,这对深入解读地下根系互作驱动的间作体系优势互补机理具有重要意义.

为明确辽宁省主要粮食作物秸秆养分资源量及其还田对化肥的替代潜力,推进全省秸秆资源化利用及化肥减施,基于统计数据和文献资料,对辽宁省水稻和玉米2种主要粮食作物的秸秆产量,秸秆N、P2O5、K2O养分资源量,以及还田条件下的养分带入量进行估算,评估其对化肥替代减施的潜力.结果表明,2018-2020年辽宁省玉米和水稻秸秆年均产量分别为2 130万、440万t.2种作物秸秆养分资源总量年均67.6万t,其中,N、P2O5、K2O分别为22.2万、7.8万、37.6万t;玉米和水稻秸秆养分资源量分别占秸秆养分资源总量的 79.4%、20.6%.单位面积水稻秸秆还田的养分当季归还量为N 23.7～40.1 kg/hm2、P2O5 5.3～9.0 kg/hm2、K2O 98.8～167.0 kg/hm2;玉米秸秆还田的养分当季归还量为N 26.2～50.6 kg/hm2、P2O5 4.4～8.4 kg/hm2、K2O 45.5～87.8 kg/hm2.水稻秸秆全量还田对氮肥(N)、磷肥(P2O5)替代潜力分别为13.2%～17.6%、6.3%～9.6%,可全部替代钾肥(K2O);玉米秸秆全量还田对氮肥(N)、磷肥(P2O5)、钾肥(K2O)替代潜力分别为12.7%～23.7%、4.80%～9.0%、46.7%～87.3%.

The application of new types of nitrogen has been regarded as one of the effective measures to improve rice yield and fertilizer utilization efficiency in China. However， it is unclear how to achieve high yield of the northern japonica rice by new types of fertilizer and fertilization methods. In this study， loss-controlled urea， urea containing zinc and humic acid urea were used to determine their effects on rice yield， economic benefit ，nitrogen uptake and use efficiency under N 200kg/ha rate. And conventional urea was set as control. The results showed that， the new types of nitrogen fertilizer could promote the growth of plant height and the formation of effective tillering of rice， and panicle formation rate was increased by 21.28%-27.90%. The application of urea loss-controlled zinc and containing humic acid increased the rice effective panicles， grain number per panicle and ear lengh， and had a significant positive correlation with yield. Compared with conventional urea treatment respectively increased the rice yield by 6.09%， 5.65% and 3.26%， the utilization rate of nitrogen fertilizer respectively increased by 23.30%， 26.21% and 30.42%， and the economic benefit increased by 5.80%-10.25%. The basal application of loss-controlled urea reduced the yield of rice by 17.17%， economic benefit reduced by 35.5%. Therefore， there were three new types of fertilizers combined with basal and topdressing are suitable for rice planting in Liaohe Plain area. which can improve rice yield， nitrogen utilization efficiency and economic benefit.

以"奇迹"番茄为试材,采用秸秆腐熟还田的方法,研究不同秸秆还田剂量和方式对番茄产量、品质和土壤理化性质的影响,以期为玉米秸秆在设施栽培中还田改良土壤提供参考依据.结果表明:多数情况下,同水平腐熟还田与未腐熟还田对土壤理化性质和产量指标影响差异不显著;腐熟秸秆还田显著提高土壤有机质、碱解氮、速效磷和速效钾,提高幅度分别为 11.66％～14.67％、15.40％～16.17％、2.30％～10.81％和 15.38％～20.10％;秸秆还田降低土壤电导率,二水平腐熟还田与未腐熟还田降幅分别为13.54％和8.58％,腐熟秸秆还田显著提高土壤阳离子交换量,二水平和四水平腐熟还田升幅分别为20.39％和16.73％,未腐熟秸秆还田显著降低土壤硝态氮含量,比同水平腐熟还田降低16.68％;秸秆还田降低土壤容重,提高土壤总孔隙度,提高土壤非毛管孔隙度,降低土壤毛管孔隙度,土壤容重降幅为11.46％～14.65％,土壤总孔隙度升幅为4.05％～13.68％,土壤非毛管孔隙度升幅为28.11％～68.10％,土壤毛管孔隙度降幅为13.47％～25.94％;秸秆还田使土壤团聚体表现为大团聚体增多,小团聚体减少的趋势;秸秆还田显著提高番茄产量和地上干物质量,提升幅度分别为6.07％～10.86％和7.93％～15.87％.

Lodging greatly reduces maize (Zea mays L.) grain yield and harvest efficiency. We conducted a 3-year (2018-2020) field experiment in Fengcheng city, Liaoning, China to investigate the effects of maize seedling defoliation on lodging resistance and grain yield. Two cultivars, Liangyu99 and Hongshuo, were tested without (control treatment) and with defoliation at seedling stage (V4 stage: DS treatment). Compared with the control, DS significantly (p < 0.05) decreased stalk lodging by 63.2%-77.9% and 51.0%-75.1%, contributing to the increase in grain yield by 4.94%-7.76% and 9.75%-19.6% for Liangyu99 and Hongshuo, respectively, during 2018-2020. The improvement of maize lodging resistance by seeding defoliation was mainly due to changes in plant morphology. On average, 12.0% and 21.9% declines in plant and ear heights, respectively, were observed and the number of internodes below the ear was reduced by 1-2 units for both cultivars with DS. A comparison of cultivars revealed that the increase in grain yield with defoliation was approximately twofold greater for Hongshuo than for Liangyu99. The greatest yield increase due to seedling defoliation was observed in 2018, when the yield was lowest with the nontreated control. However, in environments where lodging is less common, suppression of early vegetative growth would probably make little, if any, contribution to maize yield. These results suggest that defoliation of maize seedlings could be a profitable agronomic practice for maize grown in areas that experience frequent lodging.

水稻生产是碳排放的主要来源,辽宁省是中国重要的优质水稻主产区,探明稻田减排固碳潜力对实现碳达峰碳中和具有重要意义.遵循《IPCC国家温室气体清单指南2019修订版》的基本框架和要求,按照《省级温室气体清单编制指南》规定,估算分析了辽宁省稻田减排固碳潜力.结果表明,辽宁省稻田CH4排放量(CO2-eqv)为 2.13-3.39 Tg·a-1,N2O直接和间接排放量(CO2-eqv)分别为0.37-0.40 Tg·a-1和0.08-0.09 Tg·a-1.常规施肥碳排放总量(CO2-eqv)为2.61 Tg·a-1,优化施肥可减少碳排放(CO2-eqv)0.03 Tg·a-1,有机培肥和秸秆还田碳排放(CO2-eqv)分别增加0.42 Tg·a-1 和1.36 Tg·a-1,具有明显的增排效应,稻田单位面积碳排放强度和单位产量碳排放强度均以秸秆还田最高,较常规施肥分别增加了 49.96%-52.68%和 50.30%-52.46%.稻田单位面积碳排放强度(CO2)以辽河三角洲稻区最高,达到 5.17-8.08 t·hm-2·a-1.单位产量碳排放强度(CO2)则以东南部山地丘陵稻区最高,达到 0.66-1.01 t·t-1·a-1.不同水稻主产区以辽河三角洲稻区碳(CO2-eqv)减排空间最大,达 5.50×104-1.42×105 t·a-1,不同化学肥料以氮肥减施带来的碳(CO2-eqv)减排潜力最大,达0.18×104-1.20×105 t·a-1,不同养分管理措施以有机无机配施碳(CO2-eqv)减排空间最大,达3.78×104-1.42×105 t·a-1.有机无机配施和秸秆还田土壤固碳量(CO2-eqv)分别为0.10-0.28 Tg·a-1和0.22-0.65 Tg·a-1,其碳增排对土壤固碳抵消率分别为56.68%-82.52%和89.34%-99.03%,均能通过土壤固碳抵消其增加的碳排放.有机无机配施是辽宁省水稻生产碳减排最优养分管理措施.

本研究以辽宁省主要作物玉米、大豆、水稻、马铃薯、花生为研究对象,基于辽宁省统计年鉴数据,分别估算不同作物秸秆产量、秸秆综合利用不同形式温室气体减排效果进行评估.结果表明:1980-2019 年辽宁省不同作物秸秆资源量呈现前期震荡平稳、后期升高的趋势,玉米、水稻、花生呈现整体上升趋势,大豆呈整体下降趋势,2019 年秸秆资源量达到 4101 万t,其中秸秆资源量最大的作物的是玉米,其次是水稻、花生;2019 年辽宁省秸秆综合利用量约为 2330 万t,降低碳排放量 780.07 万t,综合利用率达到 86％.其中:肥料化利用量 530 万t,占比 22.7％;饲料化利用量 812 万t,占比34.8％;燃料化利用量89万t,占比38.2％;基料化利用量28万t,占比1.2％;原料化利用量70万t,占比3.1％.因此,合理利用秸秆养分资源是实现辽宁省肥料减施增效、固碳减排的重要途径.

为了明确氮肥类型和种植密度对辽河三角洲水稻产量和氮素利用的影响,选择典型稻田,以不施肥+稀植和不施肥+密植为对照,在氮肥施用量相同的基础上,设置了普通尿素+稀植、普通尿素+密植、控失尿素+稀植、控失尿素+密植处理,分析了不同处理方式下的水稻生长、产量和氮素利用率的差异.结果 表明:水稻产量和氮素利用率受到氮肥类型的显著影响,而种植密度以及氮肥类型×种植密度的交互作用对水稻产量和氮素利用率的影响不显著.与施用普通尿素相比,不管是稀植还是密植,施用控失尿素均能够提高水稻产量(6.6％～13.8％)和氮素利用率(5.4％～10.1％).而与稀植相比,密植并不能提高水稻产量和氮素利用率.虽然密植后水稻群体增大,促进了前期干物质积累、氮素吸收和有效穗形成,但减少了生育后期的吸氮量,导致穗粒数显著降低10.3％.控失尿素能够提高稀植和密植处理的有效穗,但仅增加了稀植处理的穗粒数;此外,施用控失尿素还可以通过提高吸氮量、增加氮素利用率,从而间接减少氮素盈余15.7 ～ 28.2 kg/hm2.因此,在辽河三角洲地区,采用稀植方式配合施用控失尿素就可以提高水稻产量和氮素的吸收利用,这也是适宜该地区水稻稳产高产种植的有效管理措施.

为探索有机粪肥肥料化利用对东北农区风沙土培肥地力效果,本研究采用养殖业废弃物鸡粪配施无机化肥减量20％、50％和全量替代100％处理,研究了有机培肥对土壤养分和玉米产量的影响.结果表明,与常规施肥相比,配施有机肥处理3a后土壤有机质提升了16.8％～46.4％,土壤全氮、全磷、全钾分别增加了9.22％～27.6％、23.7％～42.4％和4.16％～9.68％,土壤碱解氮、速效磷和速效钾分别增加了12.2％～29.3％、13.5％～30.4％、12.8％～17.4％.土壤施用有机粪肥替代无机化肥后,玉米植株净光合速率提高了27.9～38.3％,产量增加了8.24～31.8％,有机肥替代无机化肥减量在东北生态脆弱区风沙土上可有效起到培肥地力和作物增产效果,但用量不宜超过50％.

Intercropping cereals and legumes is practiced widely in the world for improving yields and economic benefits. Shorter legume crops in intercropping are shaded by taller cereals, substantially reducing legume growth and yield. Reducing shade in intercropping by shortening the plant height of cereals by seedling defoliation has been proposed as a practical approach to increase crop yields and land productivity. A two-year field experiment was conducted to investigate the effect of defoliation of cereal crops at seedling stage on the growth and yield of peanut (Arachis hypogaea L.) intercropped with corn (Zea mays L.) or millet (Setaria italica L.). In comparison with non-defoliation controls, defoliation reduced final plant height by 29 cm on average for corn and 18 cm for millet. Photosynthetically active radiation on peanut in intercropping systems with corn or millet intercropping was respectively 27.0% and 22.8% higher than those in controls, significantly improving the light environment of intercropped peanut. Net photosynthetic rates of peanut were on average 25.5% higher in corn and peanut intercropping and 19.6% higher in millet and peanut intercropping than those in non-defoliation controls. Total biomass of intercropped peanut increased owing to increased root growth. Across two years, yield of peanut intercropped with corn was 27.7% and with millet 32.8% higher than those of controls. Defoliation of cereal crops did not affect corn yield but significantly decreased millet yield by 24.5%. Our results suggest that applying seedling defoliation in intercropped corn could increase peanut yield without compromising corn yield in an intercropping system.

[目的]为研究水稻机插秧同步侧深施肥技术节肥增产增效的作用,改进水稻生产的养分管理方式.[方法]2019年和2020年分别在盘锦和辽阳开展大田试验,采用完全随机区组试验设计,设置不施氮肥、农民习惯施肥、侧深施减氮肥等处理,测定水稻产量及其构成因素、分析氮素利用效率和经济效益.[结果]盘锦和辽阳不同年份机插秧同步侧深施肥技术对水稻产量及经济效益的影响一致,施氮量分别比当地习惯施肥降低17.08％和17.09％,仍可获得最高(目标)产量,经济效益分别增加了1232～1440元hm—2和581～799元hm—2,处理间差异达到显著水平.减少氮肥用量后仍能获得较高产量,水稻氮肥吸收利用率(NRE)、氮肥农学效率(NAE)和偏生产力(NPFP)显著提高,与当地习惯施肥相比盘锦和辽阳减施氮肥处理NRE分别提高8.41～21.19％和10.44～15.77％,NAE分别增加2.23～3.57 kg kg—1和0.10～2.23 kg kg—1,NPFP也显著高于当地习惯施肥.[结论]在水稻稳产条件下,与当地习惯施肥相比,机插秧同步侧深施肥能够减少约17％氮肥用量,降低人工成本600元hm—2,节约肥料投入成本3.16％ ～4.53％,经济效益增加556～1370元hm—2.

在农业绿色发展的大背景下,我国肥料用量持续下降,提前实现了"到2020年化肥使用零增长"的目标.但长期降低肥料用量后,是否会对作物产量造成影响,需要进一步研究.本文基于8年的田间定位试验,以水稻为研究对象,设置N0(不施氮)、N160(氮肥用量160 kg/hm2)、N210(氮肥用量210 kg/hm2)、N260(氮肥用量260 kg/hm2,农民习惯施肥)、N315(氮肥用量315 kg/hm2)等5个施氮水平,研究长期氮肥减施对水稻产量和氮素吸收利用的影响.结果表明,与N260处理相比,N160处理产量逐年下降,且差异达显著水平;N210处理减产0.69％～1.34％,N315处理增产0.23％～0.26％或减产0.05％～1.92％,差异均未达到显著水平.可见,氮肥过量或不足,水稻产量均存在下降的风险.相关分析表明,施氮量为237.39 kg/hm2时,籽粒吸氮量最高;施氮量低于232.64 kg/hm2时,氮素收获指数保持在70.31％;施氮量为230.73 kg/hm2时,氮肥当季回收利用率最高为38.89％;施氮量为227.63 kg/hm2时,氮肥农学效率最高为15.56 kg/kg.减少氮肥用量后,氮肥偏生产力和生理利用率均有所提高.土壤供氮占水稻吸氮量的53.36％以上,施氮量低于225.95 kg/hm2时,存在消耗土壤氮库的风险.综合考虑产量和多年平均肥料利用率等数据,试验区适宜的氮肥用量为225.95～232.64 kg/hm2,可实现长期稳产增效.