热力学参数用于水稻土需钾诊断的研究

本试验测定了广东省花岗岩地区、玄武岩地区和珠江三角洲冲积物地区水稻土的钾位pK-(1/2)p(Ca+Mg)、平衡活度比AR_o^K,速效钾含量-△K^o和钾位缓冲容量PBC^K,以这些热力学参数与第1季及连续4季盆栽水稻谷粒产量和植株吸钾量参比项作相关分析,结果表明:(1)花岗岩地区水稻土pK-(1/2)p(Ca+Mg)最小,AR_o^K和-△K^o最大,玄武岩地区水稻土则相反,冲积物地区水稻土PBC^K最大.(2)pK-(1/2)p(Ca+Mg)和-△K^o适宜用于花岗岩地区水稻土当季的需钾诊断,AR_o^K对于三类水稻土都不适宜,PBC^K对于三类水稻土都适宜且能用于连续4季的需钾诊断.(3)^aCa+^aMg基本上是常数.(4)花岗岩地区水稻土pK-(1/2)p(Ca+Mg)、-RTlna_K和-△K^o对盆栽水稻临界值分别约为2.84,5400卡/克分子和0.08毫克当量/100克土,PBC^K对于全部水稻土盆栽水稻的临界值约为46[(毫克当量/100克土)]/[(克分子/升)^1/2].     

几种粘土矿物和一些土壤的钾固定

6种矿物和10个土壤样本固定的钾随加入的钾浓度增加而增加。所有样本固定的迟缓效钾很低,固定的缓效钾随矿物性质和土壤组成而变化,固定能力的顺序是:高岭石<云母<伊利石<蛭石;砖红壤和赤红壤<红壤<潮土和黄土<黄棕壤。以高岭石和蒙脱石为主并含一定量的伊利石和云母的土壤,其粘粒含量明显地影响土壤的固钾力,含较粗粒蛭石多的土壤,固钾力也明显。根据土壤的固钾率,可计算出5种施钾水平的各类土壤固钾量,为合理施用钾肥提供参考意见。     

耕作土壤非交换性钾有效性的研究

采用两种化学连续提取法及连续耗钾实验,研究了几种耕作土壤非有效性钾释放特性及有效性。结果表明,供试土壤非交换性释放特性和有效性与粘土矿的密切相关,富含伊利石的土壤非交换性钾的释放量大,速率快,有效性高,黑麦草吸收该土壤的非交换性钾量及总吸钾量高,生物量大。而富含高岭石或蒙脱石的土壤非有效性钾有效性明显较低,非交换性钾的释放量和速率,黑麦草吸收该土壤的非交换性钾量,总吸钾量及生物量的均值分别仅为富含     

吉林省主要耕作土壤中含钾矿物组成及其与不同形态钾的关系

通过化学分析 ,X-射线衍射及镜检法研究了黑土、白浆土、黑钙土等吉林省主要耕作土壤的含钾矿物组成及不同形态钾的含量。结果表明 ,土壤中的含钾矿物以含钾长石和伊利石为主 ,钾长石主要集中在土壤砂粒部分 ,伊利石主要存在于土壤的粘粒部分。土壤的含钾矿物总量约占土壤矿物总量的 1/ 3多些 ,比南方土壤高 ;缓效钾含量丰富 ,供钾潜力大 ;速效钾含量在黑土、黑钙土中较高 ,而在白浆土中稍低。 3种土壤的全钾量与含钾矿物总量、粘粒中伊利石含量与粘粒含钾量、伊利石含量与缓效钾量、细砂中含钾长石含量与细砂中全钾量、缓效性钾与速效性钾之间呈极显著或显著相关。     

南方酸化红壤钾素淋溶对施石灰的响应

为探究石灰施用的长期和短期效应对酸化红壤钾素的影响,依托始于1990年的国家红壤肥力与肥料效益监测长期定位试验,选取化肥氮磷配施(NP)、氮磷钾配施(NPK)、氮磷钾配施+半量秸秆还田(NPKS)及其增加常量石灰（NPL、NPKL、NPKSL）6个处理。室内土柱淋溶试验设置0 L、0.5 L、1 L和1.5 L石灰施用量,监测田间和淋溶后0 ~ 50 cm土层速效钾和缓效钾含量、pH及淋溶液中钾离子（K⁺）含量的变化。结果表明：1）施用石灰4年后,与NPKS、NPK、NP相比,各处理均增加了相应土层的缓效钾含量;NPKSL和NPL处理分别增加了0 ~ 40 cm和0~10 cm速效钾含量,增幅分别为2.06 % ~ 36.39 %和27.26 %。2）石灰施用量相同,各处理土壤累积K⁺淋溶量由大到小依次为NPKS处理、NPK处理和NP处理。施用石灰减少了NPKS和NPK处理淋溶液中累积K⁺含量,降幅为18.10 % ~ 57.70 %,且K⁺淋溶率也下降。3）施石灰提高了表层土壤pH;土壤中钾素盈余情况下,石灰当季施用量每增加1 000 kg·hm^-2,K⁺淋溶损失率降低11.7%;施用石灰和施肥是显著影响平均淋溶K⁺量和K⁺累积淋溶量的主效应。可见,施用石灰的短期和长期效应均能提高表层土壤pH;减少速效钾在剖面的运移,增加剖面下层缓效钾的含量;土壤淋溶K⁺量、累积K⁺淋溶量和K⁺淋溶率均随土壤中速效钾含量的增加而增加,随施用石灰而降低。合理的石灰用量能够有效降低酸化红壤K⁺淋溶损失风险。     

长期施用钾肥和稻草对红壤双季稻田土壤供钾能力的影响

以红壤双季稻区长期定位施肥试验(1981―2012年)为基础,研究了长期施用化肥和稻草对双季稻集约化种植下水稻产量、作物吸钾量和土壤供钾能力的影响。结果表明,施钾能增加水稻稻谷和稻草的产量;水稻从土壤中的吸钾量随钾肥施用量的增加而显著增加,年平均吸钾量顺序为NPK+RS(施氮磷钾化肥+稻草)NPK(施氮磷钾化肥)NP+RS(施氮磷化肥+稻草)CK(不施任何肥料)NP(施氮磷化肥);长期不施用或施用不足量钾肥(CK、NP、NP+RS)会导致耕层土壤速效钾、缓效钾和全钾数量的亏缺。长期施用钾肥和稻草不仅有利于土壤伊利石含量的增加,而且有利于晶格不良伊利石向晶格良好伊利石的方向发展;施钾能增加土壤黏粒中的游离伊利石和伊利石的含量,长期施用钾肥和稻草会使土壤黏粒中的蛭石向伊利石转化。土壤钾素的容量-强度(Q/I)曲线参数可以解释长期施用钾肥和稻草处理土壤供钾能力强是由于这些处理的活性钾(-ΔK°)量高、专性吸附钾位(Kx)多、有效钾强度(AReK)强、紧吸持K+量多,而潜在缓冲容量(PBCK)、吉布斯自由能(-ΔG)和阳离子交换系数(KG)较长期不施钾肥处理低。综上,在施氮磷肥的基础上,配施钾肥和稻草还田不仅能提高水稻高产、稳产的能力,而且对促进水稻对钾的吸收量、增强土壤的钾吸持能力、保持农田钾素平衡以及提高土壤供钾能力有重要作用。     

棉花钾素营养与土壤钾素供应水平

大田试验和田间调查分别在杭州浙江农业大学实验农场黄松土(Semihy dromorphic soil)和金华盆地红壤上进行.品种分别为钱江9号和协作2号,这两处土壤有效钾含量均较低,棉花(Gosoypium hirsutum L.)生长不良,普遍早衰.根据土壤中交换性钾的含量与棉花生长情况,一般可分为四类:土壤交换性钾>90ppm,棉花生长正常,70-90ppm,潜在缺钾;<70ppm,明显缺钾;<50ppm,严重缺钾.棉花叶片含钾量与土壤交换性钾含量呈正相关,r=0.928,显著性超过1%水准.大田试验表明,施用钾肥能提高棉花叶片含钾量,增加叶面积和叶绿素含量以及CO₂的同化率;钾还能促进叶片中细胞色素氧化酶和硝酸还原酶的活性,提高气孔导度,降低水分的蒸腾速率.缺钾叶片结构松弛,角质层发育不良;正常叶片结构紧密,角质层发育良好.叶片含钾量无论在苗期、初花期、盛花期、花铃期,均与皮棉产量呈正相关,达到显著水准.     

不同提取方法土壤非交换性钾释放动力学及其速率的研究

采用Ca2+饱和土壤的 0.50molL-1硝酸、0.0 1molL-1草酸和氢质阳离子交换树脂恒温连续提取法 ,利用Elovich和二级动力学模型 ,结合生物吸钾试验 ,研究探讨了描述土壤非交换性钾释放及其速率较为理想的连续提取法及其动力学模型。研究结果表明 ,氢质树脂提取法的Elovich模型描述非交换性钾释放及其速率的效果较为理想 ,拟合方程的相关系数达极显著水平(r =0.982～ 0.996 ) ;不同时间非交换性钾累积释放量的计算值与实测值的标准差最小 (S =1.335～2.480 ) ;通过速率方程计算的不同时间非交换性钾释放速率与黑麦草吸收的非交换性钾数量的相关性也最为密切 (r =0.944～ 0.963) ,故氢质阳离子交换树脂连续提取法结合Elovich模型是描述土壤非交换性钾释放及其速率较为理想的组合方法。以伊利石为主的 2、3和 8号土壤非交换性钾释放速率明显高于其它以高岭石或蒙脱石为主的供试土壤     

秸秆还田对水稻土黏土矿物组成和钾素释放的影响

以湖北省武穴市和荆州市长期定位试验为对象,利用X射线衍射、选择性浸提以及室内模拟等方法,研究秸秆还田下水稻土中黏土矿物组合的差异及钾素的释放。结果表明,长期秸秆还田,土壤中伊利石和高岭石增加,蛭石和1.4 nm过渡矿物(HIV)减少;长期秸秆还田配施氮磷钾肥,土壤中高岭石、蛭石和HIV增加,伊利石和绿泥石减少。长期秸秆还田,土壤中全钾、非交换性钾和交换性钾含量均增加,且土壤各形态钾素与伊利石含量呈显著正相关,与高岭石和HIV含量则呈显著负相关。0.05 mol L~(-1)草酸浸提下,土壤钾素的释放量和释放速率较大,且随浸提次数的增加,钾素的释放速率逐渐降低并保持稳定。土壤钾素的释放量与土壤非交换性钾和全钾含量呈显著正相关,伊利石和HIV是影响供试土壤钾素释放的主要黏土矿物,且二者间存在相互转化的关系。长期秸秆还田可以增加土壤的供钾能力。     

不同水氮供应对日光温室番茄土壤酶活性及生物环境影响的研究

采用2水平灌水量(4541.0和2270.6 m³/hm²)×3水平氮肥追施量(747.4、373.9 kg/hm²和0),以番茄品种Skala为试材,研究了不同水、氮供应水平对日光温室越冬栽培番茄土壤中脲酶、蔗糖酶、磷酸酶等活性及细菌、放线菌、真菌等微生物数量的影响。结果表明：高灌水(4541.0 m³/hm²)或高施氮量(747.4 kg/hm²)可显著降低土壤脲酶和磷酸酶活性;水、氮协调供应有利于土壤蔗糖酶活性和土壤微生物数量的提高;通过多目标评价,在该试验条件下,当灌水量4541.0 m³/hm²、氮肥追施量373.9 kg/hm²可获得最优的土壤生物环境。     

山西省几种典型土壤供钾能力评价

从山西省主要农田土壤中选取有代表性的耕层土壤样品 19个 ,应用生物耗竭法并结合化学方法对该省主要土壤的供钾能力进行综合评价。研究表明 ,供试的 19个土壤中无论不同形态钾含量还是耗竭后土壤钾素 (速效钾、缓效钾 )最低水平值的大小和出现前耗竭的茬数、作物吸钾量均存在较大差异 ,并因土壤类型、取土地区不同而异。最低水平值和作物吸钾量是土壤供钾的重要特征参数。供试山西土壤的长期供钾能力按取土地区有从南至北逐渐下降的趋势 ,在不同土壤类型上有红粘土、潮土 黄绵土、褐土 栗褐土、栗钙土的趋势。     

The Role of Soil Mineralogical Characteristics in Sustainable Soil Fertility Management: A Case Study of Some Tropical Alfisols in Nigeria

The pedogenic horizons of nine profile pits dug across three toposequences were studied to determine the soil mineralogical characteristics and its implications on sustainable management of the fertility of some tropical Alfisols in Nigeria. Results showed that the epipedon which were predominantly ochric had textures that ranged from sand to sandy loam, while the subsurface (B/Bt) horizons had sandy clay loam to sandy clay texture and were gravelly (31.79–83.04%). The soil reaction ranged from strongly acid to neutral (pH 5.10 to 7.05). Calcium and magnesium dominated the exchange sites and accounted for about 75% of the exchangeable bases. Illite/mica and kaolinite were the dominant minerals in the clay fractions, while quartz, mica, and feldspars dominated the fine sand and silt fractions of the soils. While the presence of illite and mica could be important for potassium nutrition in these soils, kaolinite and oxides of iron could also cause phosphorus fixation.     

广西水耕人为土黏粒矿物组成及其空间分布特征

黏粒矿物影响着土壤理化性质，可指示成土因素特征和土壤发生发育过程/强度，也是中国土壤系统分类的基层单元土族矿物学类型划分的重要依据。本研究选择了广西不同纬度和成土母质的18个代表性水耕人为土的剖面，应用X射线衍射（XRD）方法分析了其典型水耕氧化还原层（Br层）的黏粒矿物组成及其空间分布特征，并确定了其中“黏质”剖面的土族控制层段矿物学类型。结果表明：（1）供试土壤的黏粒矿物主要包括高岭石、伊利石、三水铝石、1.42 nm过渡矿物、蒙脱石和蛭石等，依次分别出现在100%、88.9%、72.2%、61.1%、44.4%和38.9%的剖面中。（2）黏粒矿物组成在纬度空间分布上具有明显规律性特征。随着纬度降低，土壤黏粒中的高岭石增加，伊利石、蒙脱石、1.42nm过渡矿物逐渐减少；纬度＞23°N区域内，成土母质对黏粒矿物组成影响明显。（3）纬度23°N是黏粒矿物组成和土族矿物学类型分界线，＜23°N区域，黏粒矿物均以高岭石为主，是“黏质”剖面的土族控制层段的主要矿物学类型；＞23°N区域，黏粒矿物组成以高岭石、蒙脱石、伊利石或1.42 nm过渡矿物为主，因成土母质不同而异，“黏质”剖面的土族控制层段矿物学类型包括高岭石混合型、混合型和伊利石型。     

The forms and availability to plants of soil potassium as related to mineralogy for upland Oxisols and Ultisols from Thailand

Potassium (K) deficiency is widespread in crops on highly weathered upland soils under a tropical monsoonal climate. Critical assessment of the forms of K in soils and of the ability of soils to release K for plant uptake is important for the proper management of K in crop production. The relationships between different pools of K were investigated as a function of silt and clay mineralogy for 14 upland Oxisols and 26 upland Ultisols soils from Thailand. Most soils contained no K-minerals in the silt fraction. XRD showed that kaolinite is the dominant clay mineral with variously minor or moderate amounts of illite, hydroxy-Al interlayered vermiculite and smectite present in some soils. For some soils, both conventional and synchrotron XRD were unable to detect illite. Analytical TEM including EFTEM of individual clay crystals showed that clay in the apparently illite-free samples contained very small amounts of illite. Many kaolinite particles appear to contain K which may be present in illite interleaved with kaolinite crystals. A glasshouse K-depletion experiment was conducted to assess the K supply capacity and changes in chemical forms of K and K-minerals using exhaustive K depletion by Guinea grass (Panicum maximum). Potassium deficiency symptoms and mortality of plants occurred on light textured soils, whereas plants survived for six harvests for Oxisols with clay texture, relatively high CEC and higher NH₄OAc-K (exchangeable K plus water-soluble K). There is a strong linear relationship of unit slope between NH₄OAc-K and cumulative K uptake by plants indicating that NH₄OAc-K is a major form of K available to plants. Thus K-bearing minerals contributed little K to plants over the time scale of the experiment and XRD patterns of whole soil samples, silt and clay from soils after cropping mostly showed no change from those for the initial soil. An exception was for a single surface soil clay where a minor amount of smectite was formed from illite by K release to plants.     

黄土区土壤钾的形态及其释放

本文研究了黄土区（陕西部分）土壤钾的形态,按毫克/100克土计,有机钾0.36-5.04,水溶性钾0.24-2.37,代换性钾3.61-16.96,有效钾3.85-19.33,非代换性钾64.45-149.77,结构钾1,840.3-2.538.3,全钾为1.920-2.640。有效钾为非代换性钾的11.42%,结构钾的0.53%和全钾的0.51%。水溶性钾和代换性钾分别是有效钾的8.2%和91.8%。通过主成分分析可知,土壤各种形态的钾与有机质呈正相关:水溶性钾、代换性钾、非代换性钾与有机态钾,代换性钾和非代换性钾与粉粒和粘粒也呈正相关,但都与沙粒呈负相关.钾的释放符合于幂回归方程（y=ax^-b）.释放量从北向南是逐渐增加的.幼年土壤和轻黑垆土耕作层释放量高于其他层次,但是粘黑垆土和黑土的粘化层的释放量高于其它层次。     

水溶性有机碳在各种粘土底土中的吸附：土壤性质的影响

Clay-rich subsoils are added to sandy soils to improve crop yield and increase organic carbon (C) sequestration; however, little is known about the influence of clay subsoil properties on organic C sorption and desorption. Batch sorption experiments were conducted with nine clay subsoils with a range of properties. The clay subsoils were shaken for 16 h at 4 ^oC with water-extractable organic C (WEOC, 1 224 g C L^-1) from mature wheat residue at a soil to extract ratio of 1:10. After removal of the supernatant, the residual pellet was shaken with deionised water to determine organic C desorption. The WEOC sorption was positively correlated with smectite and illite contents, cation exchange capacity (CEC) and total organic C, but negatively correlated with kaolinite content. Desorption of WEOC expressed as a percentage of WEOC sorbed was negatively correlated with smectite and illite contents, CEC, total and exchangeable calcium (Ca) concentrations and clay content, but positively correlated with kaolinite content. The relative importance of these properties varied among soil types. The soils with a high WEOC sorption capacity had medium CEC and their dominant clay minerals were smectite and illite. In contrast, kaolinite was the dominant clay mineral in the soils with a low WEOC sorption capacity and low-to-medium CEC. However, most soils had properties which could increase WEOC sorption as well as those that could decrease WEOC sorption. The relative importance of properties increasing or decreasing WEOC sorption varied with soils. The soils with high desorption had a low total Ca concentration, low-to-medium CEC and low clay content, whereas the soils with low desorption were characterised by medium-to-high CEC and smectite and illite were the dominant clay minerals. We conclude that WEOC sorption and desorption depend not on a single property but rather a combination of several properties of the subsoils in this study.     

A potential method to incorporate quantity/intensity into routine soil test interpretations

Abstract

Exchangeable potassium (K), extracted with 1M ammonium acetate, widely used as the measure for plant available K does not estimate the K supplying capacity of the soil. This research was undertaken to quantity the K supplying capacities of some Missouri soils and evaluate a modified K Quantity‐Intensity (Q/I) approach for adaptation into routine soil analysis. The K supplying capacities as analyzed by the modified Q/I and plant removal were measured on the 0–20 cm and 20–40 cm depths of Broseley loamy fine sand (loamy, mixed, thermic Arenic Hapludalf), Mexico silt loam, (fine, montmorillonitic, mesic Udollic Ochraqualf), Waldron clay loam [fine, montmorillonitic (calcareous) mesic Arenic Fluvaquemt] and the 0–20 cm of Sharkey clay (very fine, montmorillonitic, nonacid, thermic Vertic Haplaquet). The dominant clays in the clay fractions were identified by X‐ray diffraction to be composed of montmorillonite and illite. The high linear coefficient of correlation (R₂ = 0.92**) between the potassium buffer capacity index (KBC Index) and cation exchange capacity [CEC, sum of exchangeable Ca, Mg, K, Na, and Neutralizable Acidity (NA)] suggests that KBC Index of soils with similar clay mineral compositions, but different clay quantities, could be estimated from the measured CEC. Plant K uptake was highly linearly correlated with K quantity (Kq, R₂ =0.98**) as measured by the modified Kq/i method. It appears to be possible, using the KBC Index derived from the CEC, to calculate a Kq/i value with a single measurement of the K in equilibrium with 0.01 M CaCl₂. With the modified Kq/i method, and using this approach, a total plant available K model is presented. This modified Kq/i approach offers the opportunity for soil testing laboratories to complete a calculation for total plant available K with only one additional measurement of the equilibrium K in 0.01 M CaCl2. This would facilitate the fine tuning of soil test interpretation by basing K fertilizer recommendations on the quantity of plant‐available K in the soil.     

Potassium dynamics of a forest soil developed on a weathered schist regolith

Soils of the humid tropics are poor in available potassium due to intensive weathering and leaching of nutrients. A study was conducted to investigate the mineralogy and potassium supplying capacity of a forest soil developed on a weathered schist regolith. The quantity–intensity (Q/I) approach was used in thisstudy. The schist regolith showed deep weathering and intense leaching throughout the profile, resulting in low cation exchange capacity (CEC) and available K in soil and saprolite layers. The mineralogy of the regolith was dominanted by kaolinite, gibbsite and goethite. Feldspar, mica and mica–smectite minerals were observed in the lower saprolite layers. The Q/I parameters showed that the soils and saprolites were low in K supply power. This observation was attributed to weathering and intense leaching. The free energy values of K replacement (ΔG _r°) also suggest that soils and saprolites of the schist regolith were deficient in K. The Q/I parameters significantly correlated with organic carbon and clay content, CEC, pH and exchangeable K.     

Forms and profile distribution of potassium in typical soils of the lower Benue Valley of Nigeria

Abstract

Six profiles, derived from Precambrian Basement Complex rocks (mainly gneiss), Cretaceous sediments (mainly shale and sandstone), and Quaternary alluvium, and which are typical of the major agricultural soils in the Lower Benue Valley (Nigeria) were studied with the objective to determine their overall potassium (K) reserves and any relationship between these and other soil properties including their parent materials. Total K in the soils varies from 0.13–27.1 g kg^‐1 with average 6.64 g kg‐¹. This correlates positively with the clay, and negatively with the sand contents of the soils and is also influenced by their parent materials. The order of abundance according to parent material is: alluvium‐ > Basement Complex (gneiss)‐ ≈ shale‐ > sandstone‐derived soils. The concentrations of readily available K (RAK) in the soils are quite low, accounting for only between 0.30 and 7.8% of the total K in the soils and less than 4.0% of their exchange capacities. Based on critical limits established for many Nigerian soils, the soils derived from sandstone are clearly deficient in RAK, while soils developed from gneiss, shale and alluvium parent materials have moderate to sufficient levels for a wide range of crops. Non‐exchangeable or moderately available K (MAK) in the soils is also relatively low (0.020–8.59 mmol_c kg^‐1); while the sandstone‐derived soils have the least MAK, the alluvial soils have the most levels. However, the potassium supplying power (KSP) of the soils may be considered to be generally high. Although this bears no particular relationship to soil parent materials, the sandstone‐derived soils have the lowest KSP. The bulk of the total K reserves in the soils (55–88%) exists as difficultly available or structural K (DAK). The alluvial soils first, then the gneiss‐ and shale‐derived soils next have the highest contents of DAK, while the highly weathered sandstone soils have the lowest. Simple correlation analysis shows that, irrespective of parent material and K form, clay content and CEC are the most important soil properties influencing the overall K supplying status of these soils. It is concluded that in major agricultural soils of the Lower Benue Valley of Nigeria K exists mostly in the lattice structures of K‐bearing minerals, with accumulations in the subsurface horizons. Its plant‐available or supplying status is low on sandstone‐derived soils and moderate to sufficient on soils derived from Basement Complex rocks, shales and alluvium.