紫云英与化肥配施对安徽沿江双季稻区土壤生物学特性的影响

【目的】紫云英-水稻轮作生产体系是近年来为解决大面积冬闲田而提出的水稻生产新模式。研究紫云英-水稻轮作模式下,不同量紫云英与化肥配施对稻谷增产效果及稻田土壤生物学特性的影响,为合理施用紫云英,有效改善稻田土壤微生态环境、提高土壤质量、保证水稻高产稳产提供理论支撑。【方法】以安徽省农科院土壤肥料研究所2008年设置的紫云英-稻-稻定位试验为平台,分析了5种不同施肥模式下[不施紫云英和化肥(CK)、100%化肥不施紫云英以及70%化肥分别配施紫云英7500、15000、30000 kg/hm2])稻田耕层土壤(0—20 cm)微生物量碳、微生物量氮(SMBC、SMBN)和土壤酶活性的变化,及土壤生物学特性与土壤养分的相关性,并以水稻农艺性状和产量检验了土壤生产力。【结果】1)施用紫云英绿肥能够显著提高水稻籽粒产量,增加水稻单位面积的有效穗数和水稻结实率。尤其是70%化肥配施紫云英15000 kg/hm2处理,稻谷产量达7604.53 kg/hm2,比未施肥处理和单施化肥处理分别增产228.06%和36.29%,差异达显著水平。2)与对照相比,单施化肥处理土壤微生物量碳、氮增加,脲酶、酸性磷酸酶活性提高,过氧化氢酶活性降低;70%化肥的条件下,配施紫云英处理土壤微生物量及土壤酶活性显著高于单施化肥及对照处理,且随紫云英施用量的提高而增加。整个生育期,与对照相比,施紫云英处理土壤微生物量碳、氮分别提高21.03%~142.33%、19.97%~83.91%,土壤脲酶、酸性磷酸酶、过氧化氢酶活性分别提高10.12%~100.33%、10.22%~43.23%、0.14%~7.28%。土壤微生物量及脲酶、酸性磷酸酶与土壤有机质、全氮、碱解氮呈显著或极显著正相关;过氧化氢酶与土壤养分之间无明显相关性。【结论】紫云英绿肥与化肥长期配合施用可显著提高水稻产量、土壤微生物量及土壤酶活性,改善稻田土壤的微生态环境。本试验条件下,在70%化肥施用量的前提下,紫云英施用量以15000~30000 kg/hm2的综合效果较好。故适量紫云英与化肥配施有利于提高土壤生产能力,是安徽沿江双季稻区稻田增产和培肥地力的有效途径。     

根际注射施肥对黄土高原苹果氮素吸收利用及产量和品质的影响

【目的】在西北黄土高原地区,春季干旱少雨和肥料利用率低限制着生产优质苹果。国外通常应用水肥一体化技术来克服水肥利用率低的问题,但由于其硬件设施要求高,投资大,短期内在我国难以推广。近年来我国采用的根际注射施肥可利用施肥枪将肥料溶液直接注入根际土壤中,施肥成本低且技术简单。本研究利用同位素15N示踪技术,研究根际注射施肥对苹果氮素吸收利用及产量品质的影响,可为黄土高原果园水肥高效利用提供依据。【方法】以9年生富士/M26/新疆野苹果为试验材料,利用15N尿素标记肥料去向,最后通过MAT-251质谱计测15N丰度,得出果树各器官和土壤的肥料利用率。同时利用叶绿素仪(SPAD-502)测定标记叶片的SPAD值,用浸以磷酸甘油溶液的海绵进行田间原位测定,得到土壤氨挥发的量,用静态箱—气相色谱法测定土壤的N2O逸失量。综合对比分析黄土高原传统环状开沟撒施肥与根际注射施肥对苹果吸收利用氮素、肥料氮在土壤中残留及果实产量和品质的影响。【结果】黄土高原苹果园根际注射施肥的优越性体现在:1)施肥后一个月内,果园土壤的气态氮素损失发生变化,根际注射施肥比传统环状开沟施肥的氨挥发总量低54.9%,同时N2O的排放通量低5.0%。2)根际注射施肥后,促进了肥料在土壤中的扩散范围,扩大了根系肥水吸收容积,叶片和果实吸收的肥料氮比例(Ndff%)在整个生长季始终处于较高水平。生长季末期,根际注射施肥的整株氮素当季吸收率为53.04%,比环状开沟施肥提高12.25个百分点,表明根际注射施肥有利于氮素更快地被吸收利用,显著提高苹果树的氮素当季利用率。3)生长季末,在0—60 cm土层内,根际注射施肥的土壤氮素残留率为36.55%,而环状开沟施肥为43.13%,前者显著低于后者。4)在整个生长季内,根际注射施肥处理下的树体新梢叶片内叶绿素含量(SPAD)值一直高于环状开沟施肥。根际注射施肥能提高苹果单株产量和单果重,其单果重和单株产量分别比环状开沟施肥处理提高了3.8%和19.7%。【结论】黄土高原地区推广的果树根际注射施肥技术可以有效提高苹果树体氮素的利用率,降低了土壤中的氮素残留。此外注射施肥的深度、注射量、密度和时间均可根据不同时期的养分需要随时调整,使水肥在土壤中均匀分布,达到节水节肥的目的。同时可避免传统施肥时挖坑作业对浅土层吸收根的损伤,降低劳动力成本。综合来看,根际注射施肥是提高黄土高原区旱地苹果树肥水利用率、产量和品质的有效方式之一。     

适宜节水灌溉模式抑制寒地稻田N_2O排放增加水稻产量

2014年在大田试验条件下,设置控制灌溉、间歇灌溉、浅湿灌溉及淹灌4种水分管理模式,采用静态暗箱-气相色谱法田间观测寒地水稻生长季N2O排放特征,研究不同灌溉模式对寒地稻田N2O排放的影响及N2O排放对土壤环境要素的响应,同时测定水稻产量,以期为寒地稻田N2O排放特征研究提供对策。结果表明:不同灌溉模式下N2O排放的高峰均出现在水分交替频繁阶段,水稻生育阶段前期,各处理N2O排放都处于较低水平,泡田期几乎无N2O排放。与淹灌相比,间歇灌溉使N2O排放总量增加47.3%,控制灌溉和浅湿灌溉使N2O排放总量减少40.7%和39.6%。寒地稻田N2O排放通量与土壤硝态氮含量关系密切,与土壤10 cm温度显著相关(P0.05)。水稻生长期间各处理N2O排放顺序间歇灌溉淹灌,二者均显著高于浅湿灌溉和控制灌溉(P0.05)。各处理水稻产量以浅湿灌溉最低、其他方式差异不显著。可见,间歇灌溉有助于提高水稻产量,但会促进稻田N2O的排放。在综合考虑水稻产量及稻田温室效应的需求下,控制灌溉为最佳灌溉方式,应予以高度重视。该研究可为黑龙江寒地稻作区选择节水减排模式提供科学支撑。     

朱湾河小流域综合治理效益浅析

本文通过对朱湾河小流域综合治理生态、经济、社会效益的分析,为进一步开发利用和保护水土资源,防治水土流失,初步探索了合理可行的途径。     

水稻根际氮素状况及其利用

A greenhouse pot experiment was conducted with hybrid rice(Oryza Sativa L.) in order to study N Status and utilization in the rhizosphere of rice,The experiment was composed of three treatments:without N,15NH4-N and 15NO3-N .Plant roots were separated from the soil by a nylon cloth,and 1 mm increments of soil,moving laterally away from the roots,were taken and analyzed for various N froms.The labelled N in the plants ranged from 67\51%to 69.24% of the total amount of N absorbed by the rice seedlings with the labelled fertilizer N treatments.This shows that the N in the Plants came mainly from the fertilizers.However,the N absorbed by the rice seedlings accounted for less than 35% of the total amount of the N depletion in the soil near the rice roots,indicating an important N loss in the rhizosphere of rice.The soil redox potential(all treatments)and the concentration of the labelled NO3-N(the labelled NH4-N treatment only) decreased as the distance from the rice roots increased in the rhizosphere of rice.In contrast,the concentration of the labelled NH4-N increased as the distance uincreased in the same soil zone.These results suggested that nifrification occurred in the soil around the rice roots.Therefore,the reason for the N loss in the rhizosphere of rice might be the NO3 movement into the reductive non-rhizosphere soil(submerged) where denitrification can take place.     

Preservation of nitrifying capacity and nitrate availability in waterlogged soils by radial oxygen loss from roots of wetland plants

The effects of radial O₂ loss from roots on nitrification and NO _inf3 ^sup- availability were studied. Plants of the flooding-resistant species Rumex palustris and the flooding-sensitive species Rumex thyrsiflorus were grown on drained and waterlogged soils with an initially high nitrifying capacity. Nitrate reductase activity in the plant leaves was used as an indicator of NO _inf3 ^sup- availability to the plants. In a separate experiment these species were shown to have higher levels of nitrate reductase activity when NO _inf3 ^sup- was added to the soils compared to when only NH _inf4 ^sup+ was provided. In drained soils nitrification was maintained and both plant species showed relatively high nitrate reductase activities in their leaves. In the water-logged series planted with R. thyrsiflorus, nitrification was inhibited, NH _inf4 ^sup+ accumulated, and the plants grew less well compared to those on drained soils. In contrast, waterlogged soils planted with R. palustris had a redox potential high enough for O₂ to be continuously replenished. Furthermore, the nitrifying capacity of these latter soils was maintained at a high level. R. palustris grew well and NO _inf3 ^sup- must have been available to the plant, since a high level of nitrate reductase activity was observed in the leaves.     

青海省东部黄土丘陵沟壑区泥石流及其防治对策

青海省东部黄土高原丘陵沟壑区高寒干旱，山大沟深，沟壑纵横，生态失调，暴雨频繁，水土流失严重，滑坡、泥石流程度不同地不断发生，严重危害着工农业生产和人民生命财产安全。据调查分析，造成海东泥石流的主要成因，与暴雨、地质、气候、地形、黄土以及人为活动因素有关。防治泥石流灾害必须采取以下措施：全面普查，掌握情况；开展监测工作，进行科学试验；加快坡面、沟道治理；加强管理，依法制止人为水土流失。     

Comparison of the difference method and 15N technique for studying the fate of nitrogen from plant residues in soil

We compared the dynamics of net mineralization of nitrogen (N) derived from white clover material (Ndfc) as measured by the difference and the ¹⁵N methods in a pot experiment with a sandy loam (15°C and pF 2.4) planted with Italian ryegrass. On day 22, mineralized Ndfc (soil mineral N plus plant N uptake) was 5.8% and 1.3% of added N for the ¹⁵N and the difference methods, respectively. The discrepancy was reduced on day 43. On day 64, the relationship was reversed, and on day 98 the values given by the two methods were 22.8% and 29.5%, respectively. The results obtained by the two methods were linearly correlated (r = 0.987) and, on average, did not differ significantly. Nevertheless, the different temporal patterns led to appreciably different parameter values as estimated by fitting of a reparameterized Richards model. On day 22, clover amendment reduced mineralized N derived from soil (Ndfs) by 3.4 mg N pot^–1. The reason for this was that the clover amendment led to a reduction in plant growth and uptake of Ndfs, most likely because of allelopathy, while mineral Ndfs did not increase correspondingly. Clover-induced Ndfs in the microbial biomass of 5.1 mg N pot^–1 suggested that the mineral Ndfs not taken up by plants had been reimmobilized. Towards the end of the experiment, clover-induced Ndfs in the biomass declined to 1.5 mg N pot^–1, while mineralized Ndfs due to clover amendment increased to 5.1 mg N pot^–1. The results strongly suggested that this increase was caused by a real stimulation of humus N mineralization by clover amendment rather than by isotope displacement or pool substitution. Received: 5 May 1997     

利用航空成像光谱数据研究土壤供氮量及变量施肥对冬小麦长势影响

以推扫式成像光谱仪PHI(Pushbroom Hyperspectral Imager)获取的冬小麦拔节期、灌浆初期及乳熟期的航空影像数据为基础，提取反映冬小麦长势的光谱特征值，结合地面调查数据，分析了研究区冬小麦的长势情况；对不同时相光谱特征值与土壤基础供氮量、土壤总供氮量以及变量施肥量进行统计分析，分析结果显示：土壤基础供氮量、土壤总供氮量的空间分布差异对冬小麦长势有明显的影响，其中，土壤基础供氮量是影响冬小麦长势的重要因素，它对冬小麦的长势影响贯穿冬小麦的整个生育期；此外，该文还通过变量施肥前后作物     

植被护坡现状与展望

阐述了植被护坡的功能和发展历史。指出随着社会经济的发展,植被护坡的功能已从单纯的护坡转向护坡与景观改善并举,并且在有些情况下,以景观改善为主要目的。介绍了目前植被护坡在土质边坡、岩质边坡和水体边坡应用的主要类型与优劣,提出植被护坡存在的问题和植被护坡的发展方向。