土壤的农业化学研究的任务

在米丘林文库中,保留着一篇未完的论文稿:“向科学家要求些什么”。在这篇论文里,米丘林对于那些不能给最需要的农业问题以适当解決的学者,愤怒地写道:“例如,第一个问题:园艺家应该知道,这个区域的土壤是否适宜栽种这些植物?土壤中缺乏什么?它需要加入那些物质?并且,土壤中有什么是过多的?”     

伟大的战略 跨世纪的工程

<正>在全党和全国人民正以饱满的热情迎接党的十五大召开之际,江泽民总书记、李鹏总理等党和国家领导人就治理水土流失,建设生态农业问题作了重要批示,要求“再造一个山川秀美的西北地区”,黄土高原水土流失治理“争取15年初见成效,30年大见成效.”江泽民总书记和李鹏总理的批示,高瞻远瞩,高屋建瓴,涵盖历史,充分肯定和高度赞扬了延安、榆林地区及黄土高原治理水土流失,建设生态在业所取得的巨大成就,并对今后进一步加快水土流失治理开发步伐,改善生态环境,促进区域经济持续、快速、协调发展指明了方向,提出了殷切的希望和要求.这充分体现了党的第三代领导集体对水土保持工作的重视、支持和关心,对水土流失区广大人民群众的巨大关怀,是对全国特别是对水土流失区广大干部群众的巨大鼓舞和鞭策.我们一定要认真学习、深刻领会、坚决贯彻执行.     

被土壤吸附的六价铬的最佳提取剂的选取

通过研究土壤中磷酸盐与Ｃｒ（Ⅵ）的竞争吸附作用，查明０．１ｍｏｌ／ＬＫＨ２ＰＯ４－Ｋ２ＨＰＯ４溶液是提取被土壤吸附的Ｃｒ（Ⅵ）的最佳提取剂。     

氨的固定对土壤微生物氮的测定的影响

The effect of ammonium fixation on the estimation of soil microbial biomass N was studied by the standard fumigation-incubation(FI) and fumigation-extraction (FE) methods,NO3-N content of fumigated soil changed little during incubation,while the fixed NH4^ in soils capable of fixing NH4^ increased with the increase of K2SO4-extractable NH4-N.one day fumigation increased both extractable NH4^ and fixed NH4^ ,However,prolonged fumigation gave no further increase.One day fumigation caused significant loss of NO3-N,while prolonged fumigation caused no further loss.For soils tested,the net increases of fixed NH4^ in fumigated soil equaled to 0-94% of NH4-N flush measured by the FI metod,and 1-74% of extractable N measured by the FE method.depending on different soils.It is concluded that the ammonium fixation was one of the processes taking place in soils during fumigation as well as incubation ofter fumigation and should not be neglected in the estimation of microbial biomass nitrogen by either FI or FE method.     

施用重金属含量高的污泥的土壤重金属的有效性

<正> 为了确定Cd、Cu、Ni和Zn对生长在施用污泥的土壤上的玉米的有效性,于1984年,在就地侧渗能控制的小区进行田间试验。这些小区设在三种土壤上。这三种土壤为Bojac壤质砂土,Davidson粘壤土和Grosecloge细壤土。来自主要处理工业废水的     

土壤Se的分级与Se的植物有效性的关系

Nine soils with distinct properties and Se levels were selected to test a fractionation procedure of soil Se based on sequential extraction. Soil Se was fractionated into readily available Se (fraction Ⅰ, extracted by 0.5 M NaHCO₃), slowly available Se (fraction Ⅱ, extracted by 0.1 M NaOH-0.1 M Na₄P₂O₇), amorphous oxide-occluded Se (fraction Ⅲ, extracted by acid ammonium oxalate), free oxide-occluded Se (fraction Ⅵ, extracted by dithionite-citrate-bicarbonate buffer solution) and residual Se (fraction Ⅴ, determined by HNO₃-HClO₄ digestion of the final soil residue). The recovery of soil Se (the sum of all fractions over total soil Se determined independently) by this procedure was from 88.1% to 110.9%, mean 99.2%±6.4% for the test soils. The sum of fractions Ⅰ and Ⅱ, provided a good measure of available Se in soils and the percentage of fraction Ⅰ plus Ⅱ over the total soil Se, tentatively defined as Se availability index, could be used to indicate soil Se status and predict Se deficiency.     

提高罐藏蘑菇的得率的研究

为了探讨提高罐藏蘑菇得率的更好方法，用正交试验设计方法进一步分析浸泡-冷藏-浸泡处理与浸泡-冷藏-真空水合处理方法中各因素以及蘑菇的预煮时间、预煮液中的柠檬酸浓度对罐藏蘑菇的得率的影响。试验结果表明，在浸泡-冷藏-浸泡处理与浸泡-冷藏-真空水合处理方法中，只有冷藏处理显著影响罐藏蘑菇的得率。蘑菇的预煮时间与预煮液中的柠檬酸浓度对罐藏蘑菇的得率也有较显著的影响。将蘑菇在2℃的条件下作20～24 h的冷藏处理后再预煮，并适当延长预煮时间可提高罐藏蘑菇的得率。     

基于模糊控制的温室加热器的研究

该文分析了现有温室加热设备的不足，提出了将模糊控制原理应用于温室加温设备的新方法，并成功地研制了一种工作效率高、使用方便，基于模糊控制的温室加热器。试验结果表明，该温室加热器性能稳定可靠，自适应能力强，节能效果显著，具有较好的推广价值。     

干旱的约旦给我们的启示

世界上干旱地区约占全球陆地面积的19.6%,大部分集中在非洲撒哈拉沙漠边缘,中东、西亚和我国的西北部。半干旱地区约占27.6%,主要分布在非洲北部、欧洲南部、西南亚以及我国北方等。干旱地区的特点是降雨量少,是发生水土流失灾害问题最多的地区。位于西亚的约旦是水资源不足的国家,年平均降雨量约100 mm。约旦水土保持方案的特点是有长期水土保持设想,实施水资源再利用计划,有效利用泥沙资源,治理与绿化同步进行。相比之下,我国有些干旱地区仍存在视水土流失危害而不顾,肆意掠取自然资源的现象,有些水土保持工程也只是为治理而治理。虽然多年治理成效显著,但总趋势是流失面积在减少而侵蚀强度在增加,边治理边破坏的现象依然存在,这很值得我们深思、反省,否则,干旱贫穷的约旦将是我们前车之鉴。     

Switchgrass Influences on Soil Biogeochemical Processes in the Dryland Region of the Pacific Northwest

Switchgrass and other perennial grasses have been promoted as biomass crops for production of renewable fuels. The objective of this study was to evaluate the effect of biomass removal on soil biogeochemical processes. A 3-year field study consisting of three levels of net primary productivity (NPP; low, medium, and high growing season precipitation) and two biomass crops (winter wheat and switchgrass) was conducted near Pendleton, Oregon. Switchgrass increased soil carbon (C)–nitrogen (N) ratio, but the effect varied with net primary productivity (NPP) and soil depth. In situ soil respiration (carbon dioxide; CO₂) rate from switchgrass increased with NPP level but switchgrass had greater cumulative flux than wheat in medium and low NPP. Nitrogen mineralization and microbial biomass carbon were significantly greater under switchgrass than under wheat at high and medium NPP. Introduction of switchgrass initiates major changes in soil nutrient dynamics through organic-matter input.     

Impact of addition of different rates of rice-residue biochar on C and N dynamics in texturally diverse soils

Impacts of crop residue biochar on soil C and N dynamics have been found to be subtly inconsistent in diverse soils. In the present study, three soils differing in texture (loamy sand, sandy clay loam and clay) were amended with different rates (0%, 0.5%, 1%, 2% and 4%) of rice-residue biochar and incubated at 25°C for 60 days. Soil respiration was measured throughout the incubation period whereas, microbial biomass C (MBC), dissolved organic C (DOC), NH₄⁺-N and NO₃^–N were analysed after 2, 7, 14, 28 and 60 days of incubation. Carbon mineralization differed significantly between the soils with loamy sand evolving the greatest CO₂ followed by sandy clay loam and clay. Likewise, irrespective of the sampling period, MBC, DOC, NH₄⁺-N and NO₃^–N increased significantly with increasing rate of biochar addition, with consistently higher values in loamy sand than the other two soils. Furthermore, regardless of the biochar rates, NO₃^–-N concentration increased significantly with increasing period of incubation, but in contrast, NH₄⁺-N temporarily increased and thereafter, decreased until day 60 in all soils. It is concluded that C and N mineralization in the biochar amended soils varied with the texture and native organic C status of the soils.     

Role of soil drying in nitrogen mineralization and microbial community function in semi-arid grasslands of north-west Australia

We examined effects of wetting and then progressive drying on nitrogen (N) mineralization rates and microbial community composition, biomass and activity of soils from spinifex (Triodia R. Br.) grasslands of the semi-arid Pilbara region of northern Australia. We compared soils under and between spinifex hummocks and also examined impacts of fire history on soils over a 28 d laboratory incubation. Soil water potentials were initially adjusted to −100 kPa and monitored as soils dried. We estimated N mineralization by measuring changes in amounts of nitrate (NO₃⁻-N) and ammonium (NH₄⁺-N) over time and with change in soil water potential. Microbial activity was assessed by amounts of CO₂ respired. Phospholipid fatty acid (PLFA) analyses were used to characterize shifts in microbial community composition during soil drying. Net N mineralized under hummocks was twice that of open spaces between hummocks and mineralization rates followed first-order kinetics. An initial N mineralization flush following re-wetting accounted for more than 90% of the total amount of N mineralized during the incubation. Initial microbial biomass under hummocks was twice that of open areas between hummocks, but after 28 d microbial biomass was<2 μ g⁻¹ ninhydrin N regardless of position. Respiration of CO₂ from soils under hummocks was more than double that of soils from between hummocks. N mineralization, microbial biomass and microbial activity were negligible once soils had dried to −1000 kPa. Microbial community composition was also significantly different between 0 and 28 d of the incubation but was not influenced by burning treatment or position. Regression analysis showed that soil water potential, microbial biomass N, NO₃⁻-N, % C and δ¹⁵N all explained significant proportions of the variance in microbial community composition when modelled individually. However, sequential multiple regression analysis determined only microbial biomass was significant in explaining variance of microbial community compositions. Nitrogen mineralization rates and microbial biomass did not differ between burned and unburned sites suggesting that any effects of fire are mostly short-lived. We conclude that the highly labile nature of much of soil organic N in these semi-arid grasslands provides a ready substrate for N mineralization. However, process rates are likely to be primarily limited by the amount of substrate available as well as water availability and less so by substrate quality or microbial community composition.     

Soil microbial biomass C:N:P stoichiometry and microbial use of organic phosphorus

Microbial mineralization and immobilization of nutrients strongly influence soil fertility. We studied microbial biomass stoichiometry, microbial community composition, and microbial use of carbon (C) and phosphorus (P) derived from glucose-6-phosphate in the A and B horizons of two temperate Cambisols with contrasting P availability. In a first incubation experiment, C, nitrogen (N) and P were added to the soils in a full factorial design. Microbial biomass C, N and P concentrations were analyzed by the fumigation-extraction method and microbial community composition was analyzed by a community fingerprinting method (automated ribosomal intergenic spacer analysis, ARISA). In a second experiment, we compared microbial use of C and P from glucose-6-phosphate by adding ¹⁴C or ³³P labeled glucose-6-phosphate to soil. In the first incubation experiment, the microbial biomass increased up to 30-fold due to addition of C, indicating that microbial growth was mainly C limited. Microbial biomass C:N:P stoichiometry changed more strongly due to element addition in the P-poor soils, than in the P-rich soils. The microbial community composition analysis showed that element additions led to stronger changes in the microbial community in the P-poor than in the P-rich soils. Therefore, the changed microbial biomass stoichiometry in the P-poor soils was likely caused by a shift in the microbial community composition. The total recovery of ¹⁴C derived from glucose-6-phosphate in the soil microbial biomass and in the respired CO₂ ranged between 28.2 and 37.1% 66 h after addition of the tracer, while the recovery of ³³P in the soil microbial biomass was 1.4–6.1%. This indicates that even in the P-poor soils microorganisms mineralized organic P and took up more C than P from the organic compound. Thus, microbial mineralization of organic P was driven by microbial need for C rather than for P. In conclusion, our experiments showed that (i) the microbial biomass stoichiometry in the P-poor soils was more susceptible to additions of C, N and P than in the P-rich soils and that (ii) even in the P-poor soils, microorganisms were C-limited and the mineralization of organic P was mainly driven by microbial C demand.     

氮肥减量配施生物炭对稻田有机碳矿化及酶活性影响

氮肥减量配施生物炭对于提升土地生产力、提高土壤碳汇能力以及缓解气候变暖具有重要意义。依托大田试验,设置5个氮肥用量梯度(T0～T4):100%化肥氮,90%化肥氮,80%化肥氮,70%化肥氮,60%化肥氮,采用等氮原则,氮肥减少量用等氮量生物炭替代,以不施肥为对照(CK),结合室内矿化培养,揭示稻田有机碳矿化及酶活性对氮肥减量配施生物炭的响应。结果表明:与T0处理相比,T3处理(70%化肥氮+7.5 t/hm~2生物炭氮)土壤全氮,碱解氮及速效磷依次显著提高了6.67%,8.36%及30.94%(P0.05),T4处理的速效钾含量最高,显著提高了23.78%(P0.05)。氮肥减量配施生物炭可有效提升土壤有机碳(SOC)含量,且随配施生物炭比例的增大而增大;与矿化前相比,各处理矿化后SOC,微生物量碳(MBC)及微生物熵(qMB)依次下降1.39～1.75 g/kg, 24.62～67.57 mg/kg及0.13%～0.32%(P0.05)。SOC矿化速率在培养的第1天达到峰值,第1阶段(第1～6天)迅速下降,第2阶段(第6～30天)缓慢下降,第3阶段(第30～45天)矿化速趋于平稳,矿化速率与培养时间呈对数函数关系(P0.01)。培养结束时SOC累积矿化量和累积矿化率的变化范围分别为1.39～1.75 g/kg和6.02%～8.43%,均以T3处理最低。与CK和T0处理相比,T3处理的过氧化氢酶、脲酶和蔗糖酶活性最高,T1处理的酸性磷酸酶活性最高。水稻产量以T3处理(7.37 t/hm~2)最高,比T0处理增产39.58%(P0.05)。综上,氮肥减量30%配施生物炭可明显提高土壤肥力,减少SOC矿化,增加土壤固碳,提高土壤酶活性及水稻产量。     

Short-term effects of biochar amendment on soil microbial community in humid tropics

Biochar is known to ameliorate soil fertility and improve crop production but information regarding soil microbiota responses on biochar amendment remains limited. The experiment was conducted to study the effect of biochars from palm kernel (pyrolysed at 400°C) and rice husk (gasified at 800°C) in a sandy loam Acrisol from Peninsular Malaysia. The soil was amended with palm kernel shell biochar (PK), rice husk biochar (RH), palm kernel biochar with fertilizer (FPK), rice husk biochar with fertilizer (FRH), fertilizer and control soil. Soil samples were taken during maize harvesting and were analysed for physico-chemical properties, microbial biomass, microbial abundance and microbial diversity. Increase in pH, moisture content, CEC, organic C, and labile C were recorded in all biochar amended soils. Microbial biomass C was 65% and 36% higher in RH and FRH, respectively, than control. Microbial biomass N was greatest in FPK and FRH with respective increment of 359% and 341% than control. β-glucosidase and xylanase activities were significantly increased in all biochar treated soils than control. A shift in microbial diversity was not detected. The biochar affects the microbial community by altering the soil environment and increasing labile active carbon sources in the short-term amendment.     

Excessive Nitrogen Inputs in Intensive Greenhouse Cultivation May Influence Soil Microbial Biomass and Community Composition

Intensive greenhouse vegetable‐production systems commonly utilize excessive fertilizer inputs that are inconsistent with sustainable production and may affect soil quality. Soil samples were collected from 15 commercial greenhouses used for tomato production and from neighboring fields used for wheat cropping to determine the effects of intensive vegetable cultivation on soil microbial biomass and community structure. Soil total nitrogen (N) and organic‐matter contents were greater in the intensive greenhouse tomato soils than the open‐field wheat soils. Soil microbial carbon (C) contents were greater in the greenhouse soils, and soil microbial biomass N showed a similar trend but with high variation. The two cropping systems were not significantly different. Soil microbial biomass C was significantly correlated with both soil total N and soil organic matter, but the relationships among soil microbial biomass N, soil total N, and organic‐matter content were not significant. The Biolog substrate utilization potential of the soil microbial communities showed that greenhouse soils were significantly higher (by 14%) than wheat soils. Principal component (PC) analysis of soil microbial communities showed that the wheat sites were significantly correlated with PC1, whereas the greenhouse soils were variable. The results indicate that changes in soil microbiological properties may be useful indicators for the evaluation of soil degradation in intensive agricultural systems.     

生物黑炭对玉米苗期根际土壤氮素形态及相关微生物的影响

生物黑炭被作为土壤改良剂应用逐渐被认可,但其应用机制特别是生物黑炭对氮素形态和根际微生物的影响机理尚不明确,影响其推广。本文采用盆栽试验,研究了玉米和水稻秸秆烧制的生物黑炭按不同量施入土壤后,对玉米苗期株高、生物量和根际土壤氮素形态及相关微生物的影响。结果表明,施入60 g·kg-1玉米黑炭和40~60 g·kg-1水稻黑炭均对玉米苗期株高有显著(P0.05)降低作用,其中水稻黑炭的降低效果更为明显;分别施入60 g·kg-1玉米黑炭和20~60 g·kg-1水稻黑炭后,玉米植株地上部生物量均显著降低。施入60 g·kg-1玉米黑炭后根际土壤含水量和微生物量氮显著提高。随两种生物黑炭施入量的不断增加,玉米苗期根际土壤全氮、硝态氮含量以及固氮作用强度也显著增加,且均在60 g·kg-1施用量下达最大值。施用40 g·kg-1玉米黑炭可显著提高玉米苗期根际土壤氨态氮含量。同时,施用两种生物黑炭后,均不同程度地抑制了玉米根际土壤中细菌总体数量,促进了固氮菌和纤维素降解菌的生长,其中施入60 g·kg-1玉米黑炭的效果最为明显。综上,玉米和水稻秸秆生物黑炭的适量施用,可以促进玉米根际土壤氮素的循环转化,影响相关微生物的群落结构,且与水稻秸秆相比,玉米秸秆生物黑炭的施用效果更加明显。本文针对作物生长、土壤氮素形态及相关微生物数量3个方面研究生物黑炭施入土壤对氮有效性的影响,能够更全面、更准确地将生物黑炭如何影响土壤氮素转化展现出来,促进生物黑炭的深入开发利用,对黑土肥力保护具有一定意义。     

Drivers of microbial respiration and net N mineralization at the continental scale

The dominant pools of C and N in the terrestrial biosphere are in soils, and understanding what factors control the rates at which these pools cycle is essential in understanding soil CO₂ production and N availability. Many previous studies have examined large scale patterns in decomposition of C and N in plant litter and organic soils, but few have done so in mineral soils, and fewer have looked beyond ecosystem specific, regional, or gradient-specific drivers. In this study, we examined the rates of microbial respiration and net N mineralization in 84 distinct mineral soils in static laboratory incubations. We examined patterns in C and N pool sizes, microbial biomass, and process rates by vegetation type (grassland, shrubland, coniferous forest, and deciduous/broadleaf forest). We also modeled microbial respiration and net N mineralization in relation to soil and site characteristics using structural equation modeling to identify potential process drivers across soils. While we did not explicitly investigate the influence of soil organic matter quality, microbial community composition, or clay mineralogy on microbial process rates in this study, our models allow us to put boundaries on the unique explanatory power these characteristics could potentially provide in predicting respiration and net N mineralization. Mean annual temperature and precipitation, soil C concentration, microbial biomass, and clay content predicted 78% of the variance in microbial respiration, with 61% explained by microbial biomass alone. For net N mineralization, only 33% of the variance was explained, with mean annual precipitation, soil C and N concentration, and clay content as the potential drivers. We suggest that the high R² for respiration suggests that soil organic matter quality, microbial community composition, and clay mineralogy explain at most 22% of the variance in respiration, while they could explain up to 67% of the variance in net N mineralization.     

Microbial mineralization of biochar and wheat straw mixture in soil: A short-term study

A short-term incubation study was carried out to investigate the effect of biochar addition to soil on CO₂ emissions, microbial biomass, soil soluble carbon (C) nitrogen (N) and nitrate–nitrogen (NO₃–N). Four soil treatments were investigated: soil only (control); soil + 5% biochar; soil + 0.5% wheat straw; soil + 5% biochar + 0.5% wheat straw. The biochar used was obtained from hardwood by pyrolysis at 500 °C. Periodic measurements of soil respiration, microbial biomass, soluble organic C, N and NO₃–N were performed throughout the experiment (84 days). Only 2.8% of the added biochar C was respired, whereas 56% of the added wheat straw C was decomposed. Total net CO₂ emitted by soil respiration suggested that wheat straw had no priming effect on biochar C decomposition. Moreover, wheat straw significantly increased microbial C and N and at the same time decreased soluble organic N. On the other hand, biochar did not influence microbial biomass nor soluble organic N. Thus it is possible to conclude that biochar was a very stable C source and could be an efficient, long-term strategy to sequester C in soils. Moreover, the addition of crop residues together with biochar could actively reduce the soil N leaching potential by means of N immobilization.