秸秆覆盖量对红壤旱地棉花生长及土壤温度的影响

为探索红壤旱地较适宜的秸秆覆盖量,采取随机区组大田试验,设置4个秸秆覆盖水平:S1为0 kg/hm~2、S2为4375 kg/hm~2,S3为8750 kg/hm~2和S4为13125 kg/hm~2,研究秸秆覆盖量对红壤旱地棉花产量、出苗率、株高、叶绿素含量和土壤温度的影响。结果表明:秸秆覆盖处理(S2—S4)较不覆盖处理(S1),一是提高棉花出苗率,差异极显著(P0.01);二是影响棉花生育后期的主茎生长速度,以S4效果最好;三是可明显促进棉花叶绿素含量的增加,且以S3和S4的效果较好;四是调节土壤温度,在8:00和20:00提高土壤温度,在14:00降低土壤温度,且日均地温变化幅度小,但随着土层的加深,调温作用逐渐减弱,整个覆盖期内日均温的差值与土壤深度具有高度的相关性;五是显著增加棉花产量,S2、S3和S4分别比S1高11.4%、35.9%和37.7%,差异极显著(P0.01),且随着覆盖量的增加,增产效果逐渐提高。综合来看,秸秆覆盖在改善红壤旱地棉花产量、出苗率、株高、叶绿素含量、调节土壤温度方面发挥着重要作用,且以8750—13125 kg/hm~2效果显著,是红壤旱地值得推广的栽培模式。     

Short Communication: Characterization and succession of yeast populations associated with spontaneous fermentations during the production of Brazilian sugar-cane aguardente

A succession of yeasts was observed during fermentation of aguardente with Saccharomyces cerevisiae being the predominant species. Candida sake, Kluyveromyces marxianus var. drosophilarum and apiculate yeasts were also frequent. Transient yeast species were found in variable numbers, probably due to the daily addition of sugar-cane juice. Killer yeasts were isolated and may have a role in the exclusion of some transient and contaminant species.     

互花米草生物质能利用潜力

作为外来种,互花米草(Spartina alterniflora)对入侵地的生态系统产生了较强的干扰,但同时高生物量的互花米草也是一种潜在的生物质能源.发展生物质能是充分利用互花米草资源并控制其恶性扩张的较为有效和实用的途径,具有生态和经济双重效益.本文总结了互花米草生物质能的利用潜力,其表现为时间与空间上的生物量资源优势、高效的光合作用机制与高生产力、高贮能、较高的碳水化合物、蛋白质和脂肪储量以及不占用耕地等;同时介绍了互花米草生物质能开发利用现状,并指出互花米草生物质能的开发与利用有着光明的前景.     

Soil respiration within riparian buffers and adjacent crop fields

We quantified rates of soil respiration among sites within an agricultural landscape in central Iowa, USA. The study was conducted in riparian cool-season grass buffers, in re-established multispecies (switchgrass + poplar) riparian buffers and in adjacent crop (maize and soybean) fields. The objectives were to determine the variability in soil respiration among buffer types and crop fields within a riparian landscape, and to identify those factors correlating with the observed differences. Soil respiration was measured approximately monthly over a two-year period using the soda-lime technique. Mean daily soil respiration across all treatments ranged from 0.14 to 8.3 g C m^–2 d^–1. There were no significant differences between cool-season grass buffers and re-established forest buffers, but respiration rates beneath switchgrass were significantly lower than those beneath cool-season grass. Soil respiration was significantly greater in both buffer systems than in the cropped fields. Seasonal changes in soil respiration were strongly related to temperature changes. Over all sites, soil temperature and soil moisture together accounted for 69% of the seasonal variability in soil respiration. Annual soil respiration rates correlated strongly with soil organic carbon (R = 0.75, P < 0.001) and fine root (<2 mm) biomass (R = 0.85, P < 0.001). Annual soil respiration rates averaged 1140 g C m^–2 for poplar, 1185 g C m^–2 for cool-season grass, 1020 g C m^–2 for switchgrass, 750 g C m^–2 for soybean and 740 g C m^–2 for corn. Overall, vegetated buffers had significantly higher soil respiration rates than did adjacent crop fields, indicating greater soil biological activity within the buffers.     

Enzyme activities and substrate degradation during white rot fungi growth on sugar-cane straw in a solid state fermentation

Two strains of Pleurotus spp., grown in solid state fermentation on sugar-cane straw, degraded the dry matter by 50% after 60 days. The rate of substrate consumption and the dry weight of fruiting bodies decreased in consecutive flushings. Both strains vigorously attacked hemicellulose (80% of total degradation) and lignin (70%). Fruiting bodies were rich in protein and lipids, and had a low content of carbohydrates and ash.     

新疆农田作物覆膜地温极值的时空变化

土壤温度的上限和下限值极大地影响农田作物的生长发育．根据对新疆农田2年度不同观测时刻、不同覆膜条件及不同作物的最高和最低地温的分析,可知2年度全生育期地温极值均发生在0cm位置．地温极值依观测时刻的不同而变动．覆膜最低温度始终高于裸地,说明覆膜对提高低温段土壤温度有明显作用．最低温度的日变化可用二次函数表达;14：00和20：00时最高地温可分别用深度的椭圆曲线和线性关系表达．不同条件下的地温极值和气温具有线性关系,其中裸地最低温度与气温的相关性高于覆膜;玉米最低温度与气温的相关性高于棉花;最高温度与气温的相关性比最低温度与气温的相关性差．     

作物发育温度非线性效应Beta模型的特征分析

Beta模型在反映温度对作物发育非线性效应方面被广泛采用.为使该函数满足在设定的最适温度下函数值取值最大的条件,得到Beta模型的特殊形式.分析认为,该模型满足温度对作物发育影响的三基点规律、较好地反映发育速率对温度变化的响应特征、温度三基点在模型中应比较明确的3个规范性要求,具有较强的变化特征表达能力,可以近似表达二次函数、高斯函数等函数的变化.分析了Beta模型与积温法计算结果的关系.通过对Beta模型一阶和二阶导数的分析,明确了其变化特征,指出已有研究对参数P生物学意义解释的不妥之处,提出作物发育速度对温度的非线性响应是感温性的本质特征的观点,并从新的视角肯定了参数P在一定程度上可以作为作物感温性强弱的度量.     

Environmental factors affect the response of microbial extracellular enzyme activity in soils when determined as a function of water availability and temperature

Microorganisms govern soil carbon cycling with critical effects at local and global scales. The activity of microbial extracellular enzymes is generally the limiting step for soil organic matter mineralization. Nevertheless, the influence of soil characteristics and climate parameters on microbial extracellular enzyme activity (EEA) performance at different water availabilities and temperatures remains to be detailed. Different soils from the Iberian Peninsula presenting distinctive climatic scenarios were sampled for these analyses. Results showed that microbial EEA in the mesophilic temperature range presents optimal rates under wet conditions (high water availability) while activity at the thermophilic temperature range (60°C) could present maximum EEA rates under dry conditions if the soil is frequently exposed to high temperatures. Optimum water availability conditions for maximum soil microbial EEA were influenced mainly by soil texture. Soil properties and climatic parameters are major environmental components ruling soil water availability and temperature which were decisive factors regulating soil microbial EEA. This study contributes decisively to the understanding of environmental factors on the microbial EEA in soils, specifically on the decisive influence of water availability and temperature on EEA. Unlike previous belief, optimum EEA in high temperature exposed soil upper layers can occur at low water availability (i.e., dryness) and high temperatures. This study shows the potential for a significant response by soil microbial EEA under conditions of high temperature and dryness due to a progressive environmental warming which will influence organic carbon decomposition at local and global scenarios.     

Effects of Mulch on Seedlings and Soil on a Closed Landfill

Landfills are ideal locations for short‐rotation forestry, tree‐based bioremediation, and wildlife habitat reconstruction. However, tree survival is reduced by harsh growing conditions and poor soil quality. This study was designed to determine survival of tree seedlings and test effects of different mulch types and depths on edaphic properties and herb emergence on a closed Ohio landfill. In spring 2002, five species of hardwood tree seedlings (Fraxinus pennsylvanica, Robinia pseudoacacia, Prunus serotina, Quercus macrocarpa, and Populus sp.) were planted in a clustered fashion on 35 plots. Each plot received a mulch treatment consisting of one type of mulch (hardwood, leaf, or mixed) at a specific depth (5 or 15 cm) or was designated as a nonmulched control. The status of each seedling and edaphic qualities (soil moisture, temperature, and nutrients) were recorded for two growing seasons. Aboveground herbaceous biomass was sampled at the end of each growing season. We found that survival and growth were species dependent. At the conclusion of the experiment, Fraxinus had the highest survival rate (70%) and Prunus the lowest (7%). The use of leaf mulch (15 cm deep) increased organic matter and various edaphic properties (cation exchange capacity, P, Mg) after the second growing season. Mulch treatments did not significantly affect aboveground herbaceous biomass when compared to nonmulched controls. These results suggest Fraxinus as a good candidate for landfill plantings. Additionally, leaves and yard waste are plentiful and could quickly enrich poor soils on a landfill if left to decompose aboveground.     

半干旱区旱地春小麦全膜覆土穴播对土壤水热效应及产量的影响

以春小麦"陇春27"为试材,研究半干旱区旱地全膜覆土穴播对土壤水热效应及小麦产量的影响。结果表明:与裸地平作(CK)相比,全膜覆土穴播(PM)和全沙覆盖平作(SM)增温效果呈"挂钩型",增温效果在小麦拔节期前最为明显,PM 0-25 cm土壤平均温度较CK提高1.8 ℃,全沙覆盖平作提高1.4 ℃,拔节后PM和SM的增温效果逐渐减弱直至消失,而在成熟期又呈现较弱的增温效果。PM和SM能提高小麦出苗后耗水速度并加大耗水量,其中,小麦拔节到扬花期耗水量增加最多,分别较CK平均增加54.93%和31.54%,且此阶段越是干旱,促进耗水作用越明显,PM促进作用大于SM。PM和SM能显著提高小麦阶段性水分利用效率(WUE_b),其中PM以苗期提高最多,2a平均较CK提高365.17%,SM拔节期提高最多,2年平均较CK提高119.00%。PM和SM在增温、促进耗水作用下使小麦各生育期提前并增加单株干重,产量较CK分别平均增加432.28%和375.82%, 水分利用效率(WUE)分别平均增加351.51%和338.29%,而且越干旱年份增产效应愈加明显。可见,PM和SM在越为干旱的年份促进耗水、增产和提高WUE的作用越显著,PM效果强于SM。     

Soil temperature effects from minirhizotron lighting systems

Observing root dynamics or soil fauna with minirhizotrons requires the use of incandescent or ultraviolet (UV) lighting systems. These light sources can generate heat which would be transferred to the surrounding soil adjacent to the minirhizotron observation tubes and thus may influence root growth and development or fauna activity. The objective of this study was to determine the effect of incandescent and UV light from a minirhizotron camera system on soil temperatures next to minirhizotron tubes. Temperature probes were attached next to and at 0.5 cm from the tube surface and the tubes were then placed in boxes with either a fine sand or a loamy clay soil. Incandescent light was operated stationary for 5 min or moved at 1 cm increments every 10 s down the tube for both dry and wet soils. The UV light was used in a stationary position for 10 minutes in both dry soils. Maximum temperature increases were 3.41–3.52 °C and 1.69–2.14 °C next to the tube for the dry and wet soils, respectively with 5 min of stationary incandescent light. Ultraviolet lights increased soil temperatures to a maximum of approximately 2.5 °C in the dry soil. Probes placed 0.5 cm from the tube surface also showed temperature increases up to 2.15 °C. Moving the light source every 10 s, however, resulted in lower temperature increases (<0.8 °C). Therefore short durations of light resulted in small temperature increases suggesting minimal impact on root development. Increased soil temperatures from longer durations of light, however, may alter root growth and development as well as soil fauna activity and warrants further study.     

Root pruning reduces root competition and increases crop growth in a living mulch cropping system

Abstract

In two field experiments, growth of white cabbage in pure stands was compared with that of cabbage grown in living mulch systems to reduce pest attacks. The roots of the living mulch were pruned early in the season, with the aim of reducing competition and increasing growth of the white cabbage. Root pruning was shown to increase the above-ground biomass of white cabbage, with two prunings giving higher cabbage yields than one, but there were clear differences between the living mulch species tested (red clover, birdsfoot trefoil, salad burnet, winter rye). Below-ground growth and competition were examined by measuring root distribution in minirhizotrons and uptake of ¹⁵N placed at different soil depths. These studies showed that the ability of mulch species to compete for resources at depth was restricted by pruning, and that this was crucial for the development of the white cabbage crop.     

西北旱地春小麦不同覆盖措施的温度和产量效应

在西北半干旱雨养条件下,以春小麦为材料,研究了夏季覆膜(T1)、秋季覆膜(T2)、春季覆膜(T3)、小麦碎秆覆盖(T4)、小麦整秆覆盖(T5)、夏季覆膜+麦秆还田(T6)和无覆盖对照(CK)7个处理间0—20 cm土壤温度、产量和重要农艺指标的差异。结果表明:处理间在不同生育时期、不同土层的土壤温度存在显著差异。生育时期间比较,处理间土壤温度差异以播种期—分蘖期最大、蜡熟期—成熟期次之、拔节期—灌浆中期较小;土层间比较,处理间土壤5 cm处的温度差异依次大于10 cm、15 cm、20 cm处。T6在各时期、各土层均表现出突出的增温效应,全生育期土壤平均温度较CK高0.57℃,以成熟期、播种期及分蘖期增温效果较大;其它覆盖处理存在增温和降温的双重效应,增温效应覆膜秸秆覆盖,而降温效应则秸秆覆盖覆膜,各处理的32个土壤温度测试点中,增温点次以T4最少(仅有9个),降温点次为23个,且T4降温幅度最大,全生育期0—20 cm土壤平均温度较CK低0.63℃,降温效果在播种期和分蘖期尤为突出。覆盖处理全生育期土壤平均温度表现为覆膜CK秸秆覆盖。温差最高值出现在分蘖期土壤5 cm处的T6与T4间,T6高出T44.23℃。T6可以平抑生育期间土壤温度的变化,其它5个覆盖处理则加剧土壤温度的波动,以T4处理的土壤温度波动最明显(CV为32.4%)。处理间产量、单位面积穗数、穗粒数间差异显著,而千粒重差异不显著。无论覆膜还是秸秆覆盖,都较CK穗粒数显著增加(17.4%—36.3%)。除T5较CK显著减产14.1%外,其它覆盖处理均较CK显著增产21.7%—37.3%,其中以全膜覆土穴播基础上的秋季覆膜(T2)增产最显著,适宜在西北旱地春小麦产区推广应用。土壤温度主要影响营养生长,拔节—开花期0—20 cm的土壤温度与株高高度正相关(0.77*—0.92**),但覆盖引起土壤温度的变化最终对西北旱地春小麦产量没有关键影响。     

苏北淤泥质海岸典型防护林地土壤呼吸及其温度敏感性

土壤呼吸及其温度敏感性研究是准确估计陆地生态系统碳平衡对未来气候变化响应的基础.我国漫长的淤泥质海岸有着大面积的防护林,其碳汇服务功能是一个非常值得研究的科学问题,因此,对淤泥质海岸防护林生态系统土壤呼吸及其温度敏感性的研究具有重要的意义.研究采用碱液吸收法对苏北淤泥质海岸杨树Populus tomentosa Carr.及水杉Metasequoia glyptostroboides Hu & Cheng两种典型海防林土壤呼吸及其温度敏感性进行了研究.结果表明:杨树和水杉林地4～11月份土壤呼吸速率变化范围分别为337～732mgCO2m-2h-1和257～821mgCO2m-2h-1,呼吸通量分别为128.57gCO2m-2和121.38gCO2m-2.杨树和水杉林地土壤呼吸速率季节变化均近似单峰曲线,最大值均出现在7月份,最小值分别出现在4月份和11月份.模型R=a×exp(b×T)能够很好地拟合林内气温及土壤温度变化对土壤呼吸的影响,温度是影响土壤呼吸的主要因子,能够解释土壤呼吸季节变化的50.5%～80.9%.土壤含水量与土壤呼吸关系不显著,不是其主要影响因子.利用林内气温及土壤2、5cm和10cm处温度得到杨树林地的Q10值分别为1.45、1.97、2.08、2.01,水杉林地的Q10值分别为1.92、3.29、2.89、3.00.研究结果表明,水杉林地土壤呼吸对全球变暖的响应比杨树林地更敏感.     

Coarse pine bark mulch as open surface cover fails to improve establishment of sown native grasslands

This study was conducted across twelve agricultural locations in south-western Victoria, Australia, encompassing a range of soil types and climatic conditions. It investigated the addition of an open layer of coarse organic pine wood chip mulch (~70% surface cover) directly following direct seeding of native grassland species. The intent was to mimic positive effects of naturally occurring organic surface litter (which are typically depleted in such settings) on seedling emergence and establishment. Findings revealed negative results in that the use of an open layer of coarse pine chip mulch failed to improve native establishment at 12-months or to moderate soil temperature and moisture extremes in comparison to non-mulched plots. This outcome suggests the effectiveness of open surface mulches under the scenario of direct seeding may be highly site context, mulch-type, and application approach dependent. In situations where such mulch applications are not likely to be beneficial, significant costs relating to their purchase and application could be avoided.     

硬覆盖对土壤水热传输及作物生长发育影响的试验研究

河北省盐渍区农业水资源非常紧缺 ,农业节水势在必行。覆盖保摘技术是农田节水管理的重要措施之一 ,国内外对此有过不少研究报道。但多集中在地膜、秸秆、砂砾和化学喷涂等覆盖材料上 ,这些覆盖材料在使用中有种种不理想之处 ,如地膜覆盖容易造成残膜的“白色污染” ,并且使用年限短 ,降水不易入渗 ,中耕、除草、施肥困难 ,使作物抗病力差等[1 ] ;秸秆覆盖容易使秸秆中的毒素物质与作物间发生生化它感现象 ,影响作物生长[2 ] 。化学喷涂除了不利于农事作业外 ,还可能造成土壤污染。为此 ,我们在中国科学院南皮试区盐渍土上试用了一种新型覆…     

Optimization of Organic Mulches Thickness Improves Soil Moisture Retention under Controlled Conditions

Organic mulch can improve the moisture, chemical composition, dust, and dust suppression of soil, and beautify the environment. In view of the rapid evaporation rate and serious loss of soil water in tropical areas, this paper explored the effect of organic mulch materials with different thickness on the increase of soil water retention rate and the improvement of soil water loss caused by evaporation. Rubberwood sawdust (RWS), rubberwood bark (RWB), coconut fiber (CF), and Mulch (MC) were selected as the mulching materials. Field experiment and laboratory experiment were performed, and soil-moisture content and temperature were continuously monitored. However, from the daily measurement of water content at constant conditions (29°C ± 0.2°C, 74% ± 1% air RH) in the laboratory experiment, the results of variance analysis (ANOVA) showed that there was no significant difference between the soil-water content of covered samples and bare soil (P > 0.05). In the field experiments, the analysis of variance indicated significant differences in the soil-moisture content owing to the effect of the covering material (P < 0.01). Mulching increased the soil-moisture content with smaller fluctuations in the deep soil compared with bare soil. The most stable soil-moisture content were achieved by RWS, RWB, CF, and MC, with thicknesses of 5, 3, 7, and 5 cm, respectively, compared with bare soil, and the average water contents of the 0–40 cm soil layer was 0.58%, 0.01%, 0.82%, and 0.93%, respectively. Vertically, the intensity of the change in soil moisture decreased gradually with increasing depth, and was more stable than that of bare soil and other treatments. Among them, the difference in water content between the adjacent gradient soil layers (the soil layers are graded every 10 cm in depth) M_3–7 (0.011 ± 0.004) was the smallest. It can be concluded that CF mulching materials with a thickness of 7 cm would be preferable when selecting mulching materials for controlling soil moisture in tropical cities.     

Habitat choice in shoals of roach as a function of water temperature and feeding rate

Temperature and food availability are two important factors which affect fish growth and therefore are expected to influence habitat choice in fish. In this study, shoals of 16 juvenile roach, Rutilus rutilus , were given a choice between two chambers that differed in temperature by 1·5°C or 3°C whereas food availability was the same in both chambers (ratio 1 : 1) or higher in the colder one (ratio 4 : 1). The number of fish in each chamber was recorded for 10 min each during a pre-feeding, feeding and post-feeding period. Roach generally preferred the warmer over the colder chamber during the pre-feeding periods. Temperature had a significant effect on the distribution of fish during all three time periods whereas food availability was a significant factor only during the feeding period. The important role of temperature was emphasized further by the fact that a relatively small difference in the temperature gradient of 1·5°C had a stronger effect on fish distribution than a four times higher feeding rate during the feeding period. The implications for growth rates of such short-term decision-making of roach are discussed.     

贡嘎山树线过渡带土壤有机碳矿化和温度敏感性

树线过渡带作为高山地区重要的生态过渡带之一,是响应温度变化的敏感区域。树线过渡带内土壤碳储量丰富,其碳周转在全球碳循环方面扮演着重要角色。探究树线过渡带土壤有机碳矿化及其温度敏感性,对于预测气候变化背景下高山地区土壤碳循环过程具有重要的指导意义。为此以青藏高原东南部贡嘎山树线过渡带(森林、树线、灌丛)的土壤为对象,在室内开展90 d不同温度(15℃和20℃)的培养实验,测定土壤有机碳矿化速率,计算单位土壤有机碳累积矿化量、温度敏感性,并分析影响它们的相关因素。结果表明：土壤有机碳矿化速率受温度和样地类型的显著影响。升温显著增加土壤有机碳矿化速率,而不同样地类型间矿化速率差异显著,矿化速率大小表现为森林>树线>灌丛。本研究用单位土壤有机碳累积矿化量表征土壤有机碳的稳定性,经90 d的培养,15℃下树线过渡带从森林、树线到灌丛单位土壤有机碳累积矿化量分别为12.33 mg/g、12.99 mg/g和10.53 mg/g, 20℃下则分别为19.16 mg/g、21.14 mg/g和16.26 mg/g,灌丛土壤单位土壤有机碳累积矿化量显著低于森林和树线土壤,这表明灌丛土壤具备更...     

旱作农田不同耕作土壤呼吸及其对水热因子的响应

为研究旱作农田春玉米生育期不同耕作土壤呼吸变化特征及其对水热因子的响应情况,在山西省寿阳县旱农试验基地采用红外气体分析法测定了传统耕作(CT)、少耕(RT)和免耕(NT)土壤呼吸速率,并同步测定了各土层土壤水分、温度.研究表明:在春玉米生育期内,土壤呼吸速率均呈单峰型变化趋势,峰值出现在8月;传统耕作与少耕土壤呼吸速率变化趋势基本一致,而免耕土壤与前两者相比波动幅度较大;土壤呼吸峰值与水分、温度之间无明显相关,其余时期土壤呼吸与水分、温度因子具有良好的相关性;双因子模型较单因子模型能更好的描述土壤呼吸与水分、温度之间关系,基于水热双因子(10-20 cm)的指数-幂模型能够解释土壤呼吸变化的81％-87％ (P＜O.01);3种耕作土壤呼吸对水热因子协同影响的敏感性表现为CT＞NT＞RT.