Use of crop residues with alkaline slag to ameliorate soil acidity in an Ultisol

Information regarding the interaction between liming agents and crop residues on soil acidity amelioration is limited. A laboratory incubation study was undertaken to investigate the combined application of alkaline slag (AS, the major component is CaO) and crop residues with different C/N ratios and ash alkalinity content. Incorporation of amendments was effective in reducing soil exchangeable acidity and Al saturation and increasing exchangeable base cations (P < 0.05), but the effect of AS on soil pH adjustment was reduced when added with a high amount of residue with a low C/N ratio. Initial increases in soil pH were attributed to the release of alkalinity from the combined amendments and the mineralization of organic nitrogen (N). During subsequent incubation, the soil pH decreased because of nitrification. Crop residues with a high C/N ratio increased N immobilization and reduced net nitrification, resulting in a slight pH decrease. Crop residues with a low C/N ratio resulted in a sharp decrease in soil pH when applied with low levels of AS because of stimulated soil nitrification, whereas high AS had no consistent effect on net nitrification. Hence, compared to the control (pH = 4.21), a large increase in soil pH occurred, especially when peanut straw was applied at 10 g/kg (pH = 5.16). It is suggested that crop residues with high C/N ratio and also combined with a liming agent such as AS are preferred to ameliorate soil acidity. The liming effect of AS is likely to be negated if added in combination with residues with high N contents.     

不同改良材料对红壤酸度的改良作用及玉米生长的影响

通过盆栽试验分析了4种改良材料(生物炭、炭基肥、猪粪、石灰)及其用量对红壤pH、交换性酸、土壤养分以及玉米生长的影响。共设置10个处理:不添加改良材料的对照(CK),添加1%和3%生物炭(B1、B3),1%和3%炭基肥(BF1、BF3),猪粪替代化学氮肥20%和40%(M20、M40),0.02%和0.04%石灰(L0.02、L0.04),M20+L0.02(M20L0.02)。结果表明,与CK相比,BF3、生物炭、有机肥和石灰处理均能维持红壤pH,而BF1处理显著降低了土壤pH,降幅为0.19个单位;B3、BF1、M40和L0.04处理均显著降低了土壤交换性酸含量。BF1和BF3处理较CK土壤碱解氮含量分别增加了83和305 mg/kg;M40处理土壤有效磷含量显著增加4.1 mg/kg,而M20处理无显著差异;B1、B3和BF3处理较CK土壤速效钾含量分别增加46、138和171 mg/kg。与CK相比,BF3%处理地上部生物量显著降低37%;各改良措施间以B3处理最高,显著高于BF3、M20、L0.02、L0.04和M20L0.02处理。与CK相比,BF3处理显著增加玉米吸氮量,增幅为32%,而其它处理无显著变化。研究表明,4种改良材料均可以改善红壤酸度;综合作物生长和养分平衡,以生物炭作为红壤酸度改良材料,可适当减少钾肥投入,炭基肥则可减少化学氮、钾肥投入,以猪粪为材料则可减少化学磷肥投入。     

Use of agricultural by-products to study the pH effects in an acid tea garden soil

The amelioration of an acid Alfisol from a tea garden was studied by incorporating various plant materials: canola straw, wheat straw, rice straw, corn straw, soybean straw, peanut straw, faba bean straw, Chinese milk vetch shoot and pea straw prior to incubation for a maximum of 65 days. Soil pH increased after incubation with all the incorporated materials with the legumes causing the largest increases. The final soil pH was correlated with ash alkalinity ( r ² = 0.73), base cations ( r ² = 0.74) and N content ( r ² = 0.93) of the applied materials. It was assumed that the incubation released the base cations in plant materials as they decomposed which ultimately increased the base cation saturation of the soil. Similarly, soil exchangeable Al was also decreased with the incorporation of the legume plant materials and corn straw and rice straw. Our investigation demonstrated that legumes are the preferred choice for controlling the soil acidity and also for reducing the toxicity of Al in acid soils.     

糠醛残留物对控制土壤碱化及碱土改良的影响

Furfural residue, an industrial waste, is a kind of strongly acidic organic materials. Its comprehensive utilization in agriculture showed a significant effect on control of soil alkalization, amelioration of solonetz and increase of crop yields. In detail it may adjust pH, depress alkalinity, reduce bulk density and compactness and increase water permeability and retention ability of the soil. Meanwhile agricultural use of furfural residue provided an effective way to avoid its pollution of the soil, water and air.     

中国东南部红壤施用石灰和石膏后底土酸性的减缓

Application of lime or gypsum is a common agricultural practice to ameliorate soils with low pH which prohibits crop production. Its integrated effect on soil properties in a red soil derived from Quaternary red clay in Southeast China is discussed in this paper. Application of gypsum in the topsoil without leaching raised soil pH and promoted the production of soil NH₄, but lime addition had a contrary effect. Generally, application of lime and/or gypsum has little effect on soil electrical properties. Gypsum had a little effect on soil exchange complex and its effect went down to 30 cm in depth. The effect of lime reached only to 5 cm below its application layer. With leaching, Ca transferred from top soil to subsoil and decreased exchangeable Al in subsoil. Gypsum application led to a sharp decrease in soil exchangeable Mg but had no effect on K.     

茶树叶和刺槐叶对茶园土壤酸度的改良效果

通过培养实验,比较研究了茶树老叶和刺槐叶对2种酸化茶园土壤的改良效果。结果表明,在酸性茶园土壤中分别加入5、10和20g·kg^-1。茶树老叶和剌槐叶培养35d后,相对于对照,土壤pH值有不同程度的提高,土壤交换性酸减小,土壤交换性钙和镁等交换性盐基离子数量有所提高,土壤毒性铝离子的数量减少。2种树叶对土壤酸度的改良效果随其加入量的增加而增加,刺槐叶的改良效果好于茶树老叶,2种树叶对红壤的改良效果优于其对黄棕壤的改良效果。植物物料所含的灰化碱及豆科植物所含大量有机氮的矿化是导致土壤酸度下降的主要原因。     

复配改良剂表施对高降雨量地区茶园底层强酸性土壤酸度的调控

Strongly acidic soils (pH < 5.0) are detrimental to tea (Camellia sinensis) production and quality. Little information exists on the ability of surface amendments to ameliorate subsoil acidity in the tea garden soils. A 120-d glasshouse column leaching experiment was conducted using commonly available soil ameliorants. Alkaline slag (AS) and organic residues, pig manure (PM) and rapeseed cake (RC) differing in ash alkalinity and C/N ratio were incorporated alone and in combination into the surface (0--15 cm) of soil columns (10 cm internal diameter × 50 cm long) packed with soil from the acidic soil layer (15--30 cm) of an Ultisol (initial pH = 4.4). During the 120-d experiment, the soil columns were watered (about 127 mm over 9 applications) according to the long-term mean annual rainfall (1 143 mm) and the leachates were collected and analyzed. At the end of the experiment, soil columns were partitioned into various depths and the chemical properties of soil were measured. The PM with a higher C/N ratio increased subsoil pH, whereas the RC with a lower C/N ratio decreased subsoil pH. However, combined amendments had a greater ability to reduce subsoil acidity than either of the amendments alone. The increases in pH of the subsoil were mainly ascribed to decreased base cation concentrations and the decomposition of organic anions present in dissolved organic carbon (DOC) and immobilization of nitrate that had been leached down from the amended layer. A significant (P < 0.05) correlation between alkalinity production (reduced exchangeable acidity -- N-cycle alkalinity) and alkalinity balance (net alkalinity production -- N-cycle alkalinity) was observed at the end of the experiment. Additionally, combined amendments significantly increased (P < 0.05) subsoil cation concentrations and decreased subsoil Al saturation (P < 0.05). Combined applications of AS with organic amendments to surface soils are effective in reducing subsoil acidity in high-rainfall areas. Further investigations under field conditions and over longer timeframes are needed to fully understand their practical effectiveness in ameliorating acidity of deeper soil layers under naturally occurring leaching regimes.     

互花米草/羊粪混合堆肥还田对滨海盐碱土壤的改良效应：实验室研究

外来物种互花米草由于缺乏资源化利用途径,近年来已在我国沿海滩涂蔓延扩展。为了探索互花米草的控制与资源化利用途径,尝试将互花米草作为秸秆资源用于滨海盐碱土壤改良,为此选择适合于堆肥和还田的收割季节和部位,首先研究了不同部位互花米草成分的季节差异,结果显示,秋季互花米草秸秆的营养组分及其生物量较适合于堆肥和还田。堆肥结果表明,在耐盐菌和VT菌的共同作用下,添加羊粪后的互花米草秸秆经54d堆肥后,水浸提液的E4/E6值由初始的3.35提高到9.21,腐解过程显著;10min水洗脱盐率达到81.83%,较生米草大幅提高。8个月的盆栽（50kg级）试验表明,投加腐熟堆料后,土壤容重和含盐量降低,土壤有机碳、TN、TP、蔗糖酶活性显著提高,植物生物量为对照的3.74倍。这些结果初步表明,互花米草/羊粪混合堆肥还田能改善土壤理化性质,提高土壤肥力,增加作物产量,是一条实现资源化的可能途径。     

Extractable Acidity by a Centrifuge Method

Abstract

Titratable or extractable acidity is a measure of the acidity released by a soil to a buffered extraction solution. The United States Natural Resources Conservation Service (NRCS) Soil Survey Laboratory (SSL) routinely measures extractable acidity on soils that are carbonate free. In this study, a centrifuge method for measuring acidity extracted by barium chloride triethanolamine (BaCl₂‐TEA), pH 8.2, is described. Compared with the SSL vacuum extraction method, the proposed method provides better reproducibility for highly acidic soils, typically organic or andic materials. Key variables resolved while developing this method were extraction time and sample mass. Soil chemistry can significantly affect the pH of the extraction solution. It was concluded that checking postextraction pH is an effective way to identify samples that should be rerun by using a smaller sample size.     

烟田土壤酸化原因及调控技术研究进展

烟田土壤酸化问题已成为我国烟田土壤质量和烟草生产的主要限制因素,然而,到目前为止对烟田土壤酸化机理及调控技术尚缺乏系统性研究及总结,极大地限制了我国烟田土壤酸化改良进程和烟叶可持续生产.本文综述了近些年来国内外烟田土壤酸化机理及调控技术的研究进展,定量分析了不同致酸因子对烟田土壤酸化的贡献,揭示了盐基离子的投入和输出不...     

Nitrogen Mineralization and Nitrification in Two Soils with Different pH Levels

ABSTRACT

Soil pH is one of the properties that mostly influences nitrification rates, and can be used as a tool for controlling this process, seen that depending on its extent it may lead to nitrogen (N) losses and subsequent contaminations. The aims of this study were to evaluate mineralization and nitrification of two soils at different pH levels. The experimental design was factorial with two factors and three replicates, with the first factor referring to two samples of red latosols, one eutrophic (LV1) and the other dystrophic (LV2), and the second factor was soil’s pH, at six levels: 4.0, 4.5, 5.0, 5.5, 6.0, and 6.5. Samples were incubated for 70 days in laboratory conditions. Both nitrate (N-NO₃) and mineral N contents were determined and adjusted to growth models. The eutrophic soil presented higher mineral N and N-NO₃, and the increase of pH levels led to increases of both inorganic N and N-NO₃contents. Increases in pH levels caused N-NO₃levels to increase in both soils, however this occurrence happened because it increased the amount of mineralized N in the soil, seen that in all pH ranges in both soils practically all mineral N was in the form of N-NO₃.     

Amelioration Effects of Crop Residues with Different Chemical Components on an Acidic Tea Garden Soil

Various crop residues were applied to a strongly acidic tea garden soil to investigate their performance in ameliorating soil acidity. A laboratory study found the performance of crop residues on soil acid amelioration was mainly determined by the combined effect of nitrogen (N) transformation, cation exchange, and ash alkalinity. Nitrogen transformation was varied for different crop residues added, but followed N regulation, resulting in an adverse liming effect. It was assumed that during the release of ash alkalinity, cations replaced soil exchangeable acidity in soil solution, which largely diminished the liming effect of ash alkalinity. That was why soil pH was highly correlated with N transformation process. Furthermore, soil pH was positively correlated with carbon (C)/N ratios of crop residues both in low-level treatment (R ² = 0.955) and in high-level treatment (R ² = 0.981). Therefore, crop residues with relative high C/N ratios were considered to be more suitable for long-term pH adjustment of tea garden soils.     

生物质炭对茶园土壤改良及茶叶品质的影响

近年来,茶树种植过程中化肥的超量施用造成茶园土壤酸化加剧和有机质含量降低等一系列问题,进而影响到茶叶的产量和品质。生物质炭一般呈碱性,具有含碳量高、比表面积大、高度生物化学稳定性和较强的吸附性能等特性,能够增加土壤碳储量,提高土壤pH值和养分有效性,对于茶园土壤固碳、土壤改良和抑制土壤氮磷流失、改善农产品品质等方面有较大作用。针对我国茶园土壤存在的主要问题,以生物质炭的特性及生物质炭改良土壤的作用机理为研究对象,重点阐述了生物质炭在茶园酸化土壤改良、土壤氮素淋失阻控、土壤固碳增汇等方面的效应,以及生物质炭提高茶叶产量和提升茶叶品质方面的作用机理。基于以上研究,展望了生物质炭在茶园管理方面的理论研究方向,为生物质炭在农业生产中的应用和推广提供科学依据。