蔬菜连作对土壤生物化学性质的影响

综合分析了由蔬菜连作导致土壤条件恶化引起的土壤生物化学性质变化.分别从土壤细菌、放线菌、真菌的变化阐述土壤微生物种群与数量的变化,从土壤脲酶活性、转化酶活性、过氧化氢酶活性、磷酸酶活性等土壤酶活性的变化论述了连作对土壤酶活性的影响.并分析了连作条件下,植物残体和根系分泌物产生的自毒作用.     

不同土地利用方式下渭-库绿洲土壤盐渍化特征分析

基于渭干河—库车河三角洲绿洲土壤盐渍化现象发展的趋势,采用经典统计分析方法,对研究区不同土地利用方式下的土壤电导率、总盐量和pH值进行描述性统计分析,通过单因素方差方法对不同土地利用方式下土壤盐分指标进行差异显著性检验,并利用最小显著极差法(LSD)进行多重比较。研究结果表明:在不同土地利用方式和土层深度下,土壤电导率和总盐量的平均水平差异显著(p0.05),其含量由高到低依次为:荒漠灌丛盐碱草地耕地林地,而土壤pH值则无显著差异,土壤盐分呈现出明显的表层富集现象。本研究的结论对于提高此区域农业生产潜力和盐碱地综合治理具有重要的理论和实际意义。     

Legume cover cropping effects on early growth and soil nitrogen supply in eucalypt plantations in south-western India

Growth and soil N supply in young Eucalyptus tereticornis stands at two sites in Kerala, India, were examined in response to cover cropping with three legume species (Pueraria phaseoloides, Stylosanthes hamata, and Mucuna bracteata). The effects of legume residues on soil N supply were investigated in a long-term (392 day) laboratory incubation using leaching micro-lysimeters. Residues from the eucalypt and legume species had different rates of net N release during the laboratory incubation. Net N release was significantly related to residue N concentration (R² =0.94), the C:N ratio (R² =0.91), the lignin:N ratio (R² =0.83), and the (lignin + soluble polyphenol):N ratio (R² =0.95). Nitrogen release rates declined in the order Mucuna > Pueraria > Eucalyptus > Stylosanthes. There was no net N release from Stylosanthes residues during the 392-day laboratory incubation, whereas Mucuna and Pueraria released N throughout the incubation period. Net N release from mixtures of legume and eucalypt residues was not additive in the early phase of the incubation, probably because eucalypt residues initially immobilized a portion of the legume-derived N in addition to the soil-derived N. Legume establishment had no significant effect on tree growth at one site (Kayampoovam), but resulted in depressed tree growth at the lower rainfall site (Punnala) at 18 months. There were no significant treatment effects on growth at Punnala after that time. Cover cropping with legumes during the early phase of forest plantation growth may be a useful mechanism to enhance soil N supply and optimize the synchrony between N supply and tree N uptake. Although these effects did not translate into improved plantation growth in the 3 years of this study, improved soil organic matter and N fertility may help ensure sustainable productivity over several rotations in the future. This study showed that the effect of legumes on N dynamics varies markedly with legume species. This, together with other factors (e.g. competition with trees, N fixation capacity), will be important in selecting suitable species for cover cropping in forest plantations.     

不同经营方式对黑土水稳性团聚体组成及微粒有机质积累分布的影响

长期定位试验研究松嫩平原典型中厚黑土区水稳性团聚体组成和微粒有机质积累分布规律结果表明,不同培肥模式和耕作制度对水稳性团聚体组成有很大影响,耕地团聚体组成以<1mm水稳性团聚体占绝对优势;微粒有机碳(POM C)主要存在于水稳性大团聚体中,且其含量随粒级减小而下降,这对维持耕地黑土大团聚体(>0 .2 5mm)水稳定性起重要作用     

中国设施栽培系统中的养分管理

设施栽培养分管理是设施农业系统的重要组成部分,根据近年来我国设施农业在养分管理方面的研究进展,从设施栽培养分投入和土壤养分累积两个方面阐述了我国设施栽培养分管理现状,指出了由于不合理养分管理导致的设施栽培土壤盐分大量积累、营养元素间比例失调、设施蔬菜品质下降以及造成的环境污染等问题,并针对上述问题提出了加强设施栽培养分管理的一些具体对策及措施。     

不同种植模式下紫色土养分流失影响因子研究

通过建立5个不同种植模式的径流小区，对每个小区径流泥沙中养分的含量进行研究．探讨机械组成、微团聚体含量、粘粒团聚度等因子对养分流失影响的程度，结果发现：15～30cm土层中〈0．01mm的粘粒含量与径流泥沙中全钾含量和速效钾含量有显著的相关性。0～15cm层中的〈0．01mm和〈0．001mm微团聚体含量都与径流泥沙中有机质、速效钾和全氮的含量有显著的相关性。同层中〈0．01mm粘粒团聚度与径流泥沙中全氮含量和速效钾含量有显著的相关性，而同层〈0．001mm粘粒团聚度与径流泥沙中全磷含量、速效钾含量和速效磷含量有显著的正相关。     

等高植物篱模式下土壤物理性质变化与水土保持效果研究进展

等高植物篱模式就是在坡耕地上每隔4~8m的距离沿等高线将植物篱与作物种植带相间分布的一种农林复合经营模式,用于坡耕地的水土保持。已有的研究结果表明,等高植物篱技术用于坡耕地可有效地改善土壤物理性质和土壤水分状况,防治坡耕地水土流失效果显著,土壤水分的季节性再分配也有利于农作物的生长。但是该系统内植物篱和农作物相互之间的水分和养分关系有待深入研究。     

Long-term continuous cropping in the Pacific Northwest: Tillage and fertilizer effects on winter wheat, spring wheat, and spring barley production

Conventional tillage winter wheat (Triticum aestivum) (WW)–summer fallow reduces soil productivity and increases soil erosion. Conservation tillage management, together with intensive cropping may have the potential to reverse these sustainability concerns. The objective of this study was to determine the effects of conventional tillage (CT) and no-tillage (NT) systems on grain yield of long-term annual cropping of monoculture WW, spring wheat (SW), and spring barley (Hordeum vulgare) (SB) grown with or without fertilizer, in the Pacific Northwest region of the USA. In unfertilized crops, grain yield of WW, SW, and SB was 15%, 25%, and 50% higher, respectively, in CT than in NT plots, an indication of the involvement of yield limiting factors under the NT cropping system. When fertilized, there were no significant differences in grain yield of WW. Yields of SW and SB, however, remained 21% and 15% higher, respectively, in CT than in NT, an indication that factors other than fertility were involved. These results suggest that in order for NT management to be widely adopted by area growers, the yield-limiting factors need to be addressed.     

广西旱地分带间套轮作试验示范研究

于1986～1988年,在广西六个县、市进行了旱地分带种植试验、示范,已取得了预期效果。(1)经济产量比对照高187.9kg/亩,增产44.4%;(2)纯收入比对照高108.1元/亩,增收83.7%;(3)每个工日产粮、产值比对照分别高7.6 kg、2.7元/工,增54.7%、37.0%;每元投入产粮、产值比对照分别高1.2kg、0.7元,增33.3%、41.2%; (4)产/投能量效率高31%;每投一单位辅助能,产生物能,食物能比对照分剐高400kcal、120kcal;光能利用率及光能生产率此对照分别多0.17%,0.1%;(5)土地等量比率(L.E.R)为对照的4.4倍;(6)土壤肥力比对照有所提高。