A Comparative Study of the Use of Organic Carbon and Loss on Ignition in Defining Tropical Organic Soil Materials

Organic soils or Histosols or peats as they are commonly referred to, are characterized by the presence of large amounts of organic soil materials (OSM), which is commonly quantified by the Walkley and Black (1934) (WB) method to determine the soil organic matter (SOM) using a correction factor of 1.724. SOM of Histosols is also identified through a combustion (loss on ignition, LOI) or elemental C-analysis (with a carbon-nitrogen-sulfur (CNS) analyzer with combustion and gas density detector). These methods were established using temperate and boreal peat deposits and here we demonstrate that tropical peat deposits require a modified approach. Typical SE-Asian tropical lowland peat pedons from rain forest and oil palm settings were sampled and the material analysed using a CNS analyzer, WB-C and LOI. The ratios for LOI:CNS-C for the 20 samples yielded values between 2.00–3.09 with a mean of 2.50 while the LOI:WB-C ratio yielded values from 1.75 to 2.58 with a mean of 1.94. A comparison of these values for topsoils and subsoils showed mean ratios (LOI:WB-C) of 1.94 and 1.89 for topsoils and subsoils, respectively. The forest samples had higher LOI:WB-C ratios than the subsoils from oil palm settings (1.94 vs 1.84). These values suggest that the standard factor of 1.724 to correct OSM to SOM for tropical soils is untenable. The values to convert CNS and WB-C values of tropical topsoils/subsoils to SOM or LOI should be 2.5 or 1.9, respectively. Our results indicate a significant difference in the soil organic carbon (SOC) of tropical lowland peats depending on the method used.     

Changes in soil carbon and crop yield over 60 years in the Zurich Organic Fertilization Experiment,following land‐use change from grassland to cropland

Changes in land‐use and agricultural management affect soil organic C (SOC) storage and soil fertility. Grassland to cropland conversion is often accompanied by SOC losses. However, fertilization, crop rotation, and crop residue management can offset some SOC losses or even convert arable soils into C sinks. This paper presents the first assessment of changes in SOC stocks and crop yields in a 60‐year field trial, the Zurich Organic Fertilization Experiment A493 (ZOFE) in Switzerland. The experiment comprises 12 treatments with different organic, inorganic and combined fertilization regimes. Since conversion to arable land use in 1949, all treatments have lost SOC at annual rates of 0.10–0.25 t C ha^?1, with estimated mean annual C inputs from organic fertilizers and aboveground and belowground plant residues of 0.6–2.4 t C ha^?1. In all treatments, SOC losses are still in progress, indicating that a new equilibrium has not yet been reached. Crop yields have responded sensitively to advances in plant breeding and in fertilization. However, in ZOFE high yields can only be ensured when mineral fertilizer is applied at rates typical for modern agriculture, with yields of main crops (winter wheat, maize, potatoes, clover‐grass ley) decreasing by 25–50% when manure without additional mineral fertilizer is applied. ZOFE shows that land‐use change from non‐intensively managed grassland to cropland leads to soil C losses of 15–40%, even in rotations including legumes and intercrops, improved agricultural management and organic fertilizer application.     

Pine sawdust as stimulator of the microbial community in post-arable afforested soil

Sawdust and wood residues are considered to be stimulators of microbiological change in soil and could be used in post-arable sites designed for afforestation. In this study, we discuss changes in bacteria numbers within selected groups in relation to soil type (arable and forest) and method of sawdust application. Sawdust was spread along planting rows and mixed with the soil or put directly under roots of planted seedlings. Applying sawdust under the roots increased the number of cellulolytic bacteria in all experimental treatments. On post-arable soil, adding sawdust in rows increased the number of copiotrophic bacteria and reduced the number of fluorescent bacteria and actinomycetes (ACT). In control forest soils, the number of copiotrophic, oligotrophic and spore-forming bacteria decreased simultaneously with increased ACT in all treatments. The number of fluorescent bacteria increased when sawdust was applied on forest sites under planted trees and decreased when sawdust was spread in planting rows. Oligotrophic bacteria also decreased in the latter case. We present a list of bacteria identified by DNA – 16S rRNA gene sequences. Adding sawdust to arable soils significantly changed the quantitative and qualitative composition of microbial communities.     

园林废弃物堆肥对铅镉污染土壤的修复效果

为明确园林废弃物堆肥（GWC）对重金属污染土壤的修复效果,通过小白菜盆栽试验,向铅（Pb）、镉（Cd）污染土壤中分别按0（CK）、1%、3%、5%的施用量添加GWC和泥炭,研究不同单一/混合处理对土壤酶活性,Pb、Cd在土壤孔隙水中浓度和在土壤中赋存形态的影响,并探究小白菜地上部和根部Pb、Cd积累转运的关系。结果表明：各处理3%和5%的施用量显著提高了土壤酶活性,5%泥炭对提高脱氢酶和过氧化氢酶活性更显著,5% GWC对提高脲酶和磷酸酶活性更显著。土壤孔隙水Pb浓度在第1~7 d时随不同处理的施用量增多而降低;5% GWC及5%混施处理在第1 d时的Pb浓度与CK相比分别降低了78%和56%。不同处理中孔隙水Cd浓度在第1 d时均高于CK,其中5% GWC相比CK增加了70%;泥炭处理中Cd浓度随时间延长呈现先上升后下降的趋势。3%和5%处理下土壤酸溶态Pb、Cd显著减少,残渣态显著增加,植株地上部和根部Cd含量显著下降,富集系数和转运系数也相应降低,其中5%混合施用效果最显著。Pb含量在3%和5% GWC施用下显著上升。研究表明,单一、混合施用GWC及泥炭对土壤中Pb、Cd有显著的钝化效果,且泥炭对于降低植物体重金属积累的效果好于GWC。     

几种有机废弃物作为一品红代用基质的研究

为减少花卉无土栽培对泥炭资源的依赖,该试验以玉米秆、麦秆、锯末和菇渣4种有机废弃物作为基质的主要成分,探讨取代泥炭作为一品红栽培基质的可行性。结果表明,V(玉米秆粉)∶V(珍珠岩)为3∶1、V(菇渣)∶V(珍珠岩)为3∶1、V(菇渣)∶V(蛭石)为3∶1,这3个处理的理化性质的各项指标均在无土栽培基质的理想范围内,用其栽培的一品红根系生长健壮,生长发育综合表现显著优于对照,可作为一品红无土栽培的代用基质。      

泥炭资源农业利用现状与前景

本文概述了国内外泥炭农业利用方面所是的进展,评价了我国泥炭资源的储量、质量状况,根据我国泥炭性质和质量特性,在分析泥炭研究开发经验教训的基础上,提出了重点开展泥炭农业利用,特别是加强泥炭高新技术产品开发的建议。作者根据自己的研究成果,对泥炭农业利用的前景进行了展望。     

呼市地区春末夏季栽培双孢蘑菇初探

呼市地区春末夏季在自然条件下可以人工栽培双孢蘑菇。栽培菌株102—2。培养基质以麦秸,鸡粪、羊粪、尿素、石膏为主,经过予堆,一次发酵,二次发酵后上床播种,覆土。采收二潮每平方米收鲜切脚菇7.3公斤。二潮以后由于培养基质被害虫严重为害,未有产量。     

蚯蚓处理椰子废弃物和畜禽粪混合物的研究

通过将椰糠、椰子枯落叶分别与牛粪、鸡粪混合．按10条／hg风干堆料接种蚯蚓后．在相同的条件下饲养,分别于10、20、30、40d时测定蚯蚓的生长繁殖情况．以及测定蚯蚓处理有机肥前后的理化性状。结果表明,随着时间的增加,蚯蚓的均重、日增重、日繁殖倍数均呈现先增加后减少的趋势．且不同时期、不同组合间均差异显著（P〈O．05）,以椰糠、椰子枯落叶和牛粪组合的生长繁殖优于椰子凋落叶和鸡粪组合：蚯蚓处理后有机肥的pH、有机碳含鼍和C／N下降,全氮和全磷含量上升,且碳含量和C／N在处理前后均达到显著水平．但pH和磷含量在蚯蚓处理前后均无显著差异。     

黄腐植酸对泥炭产甲烷的影响

为研究泥炭自有成分黄腐植酸对泥炭产甲烷的影响,提升甲烷产量,在草本泥炭产甲烷发酵反应系统中分别加入0(CK)、5(T5)、10(T10)、50(T50)和100 mg·L^-1(T100)黄腐植酸,分析为期43 d发酵反应过程中的总产气量、日产气量、还原糖含量、挥发性脂肪酸(volatile fatty acids,VFA)含量和pH的变化规律。结果表明,CK处理的甲烷总产量为16.57 mL·g^-1,T5、T10、T50、T100处理的总产气量分别为21.23、15.55、15.30、11.45 mL·g^-1,其中T5处理的甲烷总产量最高,为CK的1.28倍。各发酵组均于第8或第9天达到产气峰值,其中T5处理在第9天达到1.81 mL·g^-1的产气量最高峰,是CK处理的1.70倍。且添加黄腐植酸可促进还原糖和VFA降解,同时使发酵系统的pH更适于产甲烷菌生存。综上所述,泥炭自有成分腐植酸中可溶于水的黄腐植酸对泥炭产甲烷具有显著促进作用。