施肥对免耕旱作燕麦田土壤温室气体排放的影响

采用静态箱-气相色谱法,研究了不施肥(CK)、施氮肥(N)、施磷肥(P)、施钾肥(K)、氮磷肥配施(NP)和氮磷钾肥配施(NPK)5种施肥处理对免耕旱作燕麦田土壤温室气体排放的影响,以期为当地农田生态实现可持续发展提供科学依据。结果表明,各处理土壤CO_2排放通量随燕麦生育期均呈先增加后减小的趋势,拔节期出现峰值;不同施肥处理CO_2平均排放通量均高于不施肥处理,其中氮磷钾配施、氮磷配施和施氮处理与不施肥处理间差异显著;各处理土壤CH_4排放通量在全生育期内均表现为吸收特征,呈"反S型"变化,全生育期氮磷钾、氮磷和施氮处理CH_4平均吸收通量显著高于不施肥处理,分别是不施肥处理的1.30、1.25、1.15倍,三者之间差异不显著;各处理N_2O排放通量全生育期内均表现为排放源,呈先增后减的趋势,各处理N_2O平均排放通量表现为施氮氮磷配施氮磷钾配施施磷施钾不施肥,其中施氮、氮磷配施、氮磷钾配施与不施肥处理差异显著,施磷、施钾与不施肥处理差异不显著;氮磷钾配施、氮磷配施、施氮、施磷、施钾处理综合温室效应分别比不施肥处理高22.3%、15.6%、12.8%、10.1%和4.7%,除施钾处理外,其他施肥处理均与不施肥处理差异显著。     

灌溉方式和氮肥运筹对免耕厢沟栽培杂交稻氮素利用及产量的影响

【目的】免耕厢沟是四川重点推广的水稻栽培模式。研究该模式下不同灌溉方式和氮肥运筹对水稻干物质累积、转运和氮素利用效率等的影响,可为免耕厢沟水稻栽培水肥管理提供依据。【方法】 以杂交中稻F优498为试验材料,采用两因素裂区设计,主区为传统水层灌溉(W1)和干湿交替灌溉(W2)两种灌溉方式,副区为氮肥运筹模式,在总施氮量为150 kg/hm2条件下,设置基肥 ∶蘖肥 ∶穗肥分别为6 ∶2 ∶2(N1)、 4 ∶2 ∶4(N2)、 2 ∶2 ∶6(N3)等3种氮肥运筹模式,以不施氮(N0)为对照,研究免耕厢沟模式下,杂交稻在齐穗期、成熟期各处理下干物质氮素积累、茎鞘的干物质转运、产量及其构成因子以及氮素利用效率。【结果】 灌溉方式和氮肥运筹对水稻主要生育期干物质量和氮吸收、转运及产量具显著影响及互作效应。干湿交替灌溉能扩“库”增“源”,保证足够的穗数,提高干物质积累量;淹水灌溉无效分蘖较多,群体质量变差,对干物质积累、氮素吸收、产量造成不利影响。适宜的前氮后移能为水稻整个生育期提供比较平衡的氮素供应,促进氮素的吸收、 提高氮素积累、协调氮素分配;N2模式下氮素表观利用率达69%以上,氮肥的农学利用效率、表观利用率比N1(6 ∶2 ∶2)和N3(2 ∶2 ∶6)分别高4.50%~36.85%、 8.09%~28.54%,增产7.47% ~15.76%。合理的水氮管理显著提高各生育期的氮素积累量,促进齐穗后叶和茎鞘氮素向穗的运转量。【结论】 干湿交替灌溉(W2)和氮肥运筹4 ∶2 ∶4(N2)为本试验条件下的最优水氮运筹模式,其充分发挥了水氮耦合优势,促进齐穗后“源”(茎鞘、叶)氮素向“库”(穗)的运转,有利于高产群体构建,有效提高氮素利用率,提高水稻每穗实粒数和结实率,增产效果显著。     

不同耕作方式对水稻固氮酶活性的影响

在免耕、常耕等4种不同耕作方式条件下,在水稻不同生育时期研究不同耕作方式对水稻固氮酶活性的影响。试验结果表明:在灌浆期和成熟期,常耕和稻草免耕处理的水稻总固氮酶活性相对高于其他两个处理;从灌浆期至成熟期,各处理的总固氮酶活性明显下降,下降程度由大到小是稻草常耕>常耕>稻草免耕>免耕,说明不施稻草、免耕方式较常耕方式能延缓成熟期水稻固氮酶活性的降低。在不同时期,均以水稻茎的固氮酶活性最高,叶片的最低;从灌浆期至成熟期,不同处理水稻根、茎固氮酶活性明显降低,叶片的变化最小。因此,不同生育时期和耕作方式对水稻根、茎固氮酶活性影响明显,而对叶片固氮酶活性影响较小。     

水稻编织布育秧免耕抛秧技术试验

水稻编织布育秧免耕抛秧技术试验结果表明五种育秧方式中,以编织布育秧免耕抛秧产量最高,效益最好,与353、434和561穴孔塑盘育秧相比,增产7.9-16.1%,增收21.9-43.1%;其次是畦面育秧,比塑盘育秧增产5.5-13.6%,增收15.4-35.5%。增产增收主要原因是苗素质好,抛后立苗生长分蘖快,有效穗数多,穗大粒多,同时每667m2节约塑盘成本12-15元。     

超级稻免耕不同抛栽密度对比试验

2007年晚稻进行超级稻免耕不同抛栽密度对比试验。结果表明,每667m2施纯N 13kg、P2O56.5kg、K2O13kg,以每667m2抛栽1.7万蔸产量最高,比抛栽1.3万蔸和1.5万蔸增产8.6%和5.4%,比抛栽1.9万蔸和2.1万蔸增产6.8%和9.5%。     

玉米免耕播种机免耕播种试验研究

玉米免耕播种机是与玉米留茬免耕技术配套的播种机具。3年的大面积田间试验结果表明：使用玉米留茬免耕播种机播种能抵御春旱和季节性“掐脖旱”,提高产量15％～35％,增加利润约10％。使用玉米留茬免耕播种机还具有减弱水气蒸发、防止水土流失的作用。     

2BF-7型多功能免耕施肥播种机的研制

在分析传统播种机不适应我国北方干旱或半干旱地区施行保护性免耕施肥播种原因的基础上.针对存在的问题,采用种肥同沟施播的组合式开沟器来减少开沟器数量,改变铲柱一字形排列为三角形排列,改变开沟器安装形式加长铲柱高度等方法,并在新研制的2BF-7型多功能免耕施肥播种机上得以试验验证.结果表明,提供的方法可靠、有效,可供相关单位在开发新型免耕施肥播种机时参考借鉴.     

我国玉米免耕播种机械化技术发展研究

介绍我国玉米免耕播种机械化技术发展现状,分析影响其推广应用的主要因素,并依此提出完善玉米作物育种系统、加强玉米免耕播种机的研制、建立和完善玉米免耕播种机械化技术体系等有效措施,以推动我国玉米免耕播种机械化技术的进一步发展。     

Inter-annual changes in the aggregate-size distribution and associated carbon of soil and their effects on the straw-derived carbon incorporation under long-term no-tillage

Converting from conventional tillage to no-tillage influences the soil aggregate-size distribution and thus soil organic carbon(SOC) stabilization. However, the dynamics of soil aggregation and the straw-derived carbon(C) incorporation within aggregate fractions are not well understood. An experiment was established in 2004 to test the effects of two treatments, no-tillage with residue(NT) and conventional tillage without residue(CT), on the soil aggregate-size distribution and SOC stabilization in a continuous maize(Zea mays L.) cropping system located in the semiarid region of northern China. Soil samples were collected from the 0–10 cm layer in 2008, 2010 and 2015, and were separated into four aggregate-size classes(2, 0.25–2, 0.053–0.25, and 0.053 mm) by wet-sieving. In each year, NT soil had a higher proportion of macroaggregates(i.e., 2 and 0.25–2 mm) and associated SOC concentration compared with CT. Additionally, to compare straw-derived C incorporation within NT and CT aggregate fractions, 13 C-labeled straw was incubated with intact NT and CT soils. After 90 days, the highest proportion of 13 C-labeled straw-derived C was observed in the 2 mm fraction, and this proportion was lower in NT than that in CT soil. Overall, we conclude that long-term continuous NT increased the proportion of macroaggregates and the C concentration within macroaggregates, and the physical protection provided by NT is beneficial for soil C sequestration in the continuous maize cropping system in semiarid regions of northern China.     

Integrated tillage-water-nutrient management effects on selected soil physical properties in a rice-wheat system in the Indian subcontinent

We studied few soil physical indicators after eighth cropping cycle of rice-wheat. The experiment was laid out in split-split plot design with two tillage (rice: puddling vs. non-puddling; wheat: conventional tillage vs. no-tillage), three water management (rice: submergence vs. drainage; wheat: five/three/two irrigations) and nine nutrient (N) management treatments (inorganic vs. integrated nutrient management). The bulk density (t m^?3) in non-puddled soil (1.33) was significantly less than puddled soil (1.59); while mean weight diameter (0.55 mm) and saturated hydraulic conductivity (0.43 cm h^?1) were higher in the former treatment. Irrigation after 3-days of drainage was found to enhance soil aggregation (0.54 mm) and moisture retention (71.6%) during rice. No-tillage in wheat had overall positive impact. Organic sources of nutrients increased soil water retention (biofertilizer for rice), water conductivity and aggregate stability (combined organics for rice and wheat). Interactions between (tillage × N), (water × N), (tillage × water) revealed crop-wise variations. The saturated hydraulic conductivity and soil aggregation for rice; and bulk density, water retention and saturated hydraulic conductivity for wheat were identified as sensitive soil physical indicators. We suggest an effective combination of no tillage and intermittent irrigation with integrated nutrient management for sustaining soil physical quality in rice-wheat rotation.