Effect of Long-Term Application of K Fertilizer and Wheat Straw to Soil on Crop Yield and Soil K Under Different Planting Systems

Effect of application of K fertilizer and wheat straw to soil on crop yield and status of soil K in the plough layer under different planting systems was studied. The experiments on long-term application of K fertilizer and wheat straw to soil in Hebei fluvo aquic soil and Shanxi brown soil in northern China were begun in 1992. The results showed that K fertilizer and straw could improve the yields of wheat and maize with the order of NPK ＋ St 〉 NPK 〉 NP ＋ St 〉 NP, and treatment of K fertilizer made a significant difference to NP, and the efficiency of K fertilizer in maize was higher than in wheat under rotation system of Hebei. In contrast with Shanxi, the wastage of soil potassium was a more serious issue in the rotation system in Hebei, only treatment of NPK ＋ St showed a surplus of potassium and the others showed a wane. K fertilizer and straw could improve the content of water-soluble K, nonspecifically adsorbed K, non-exchangeable K, mineral K, and total K in contrast to NP; however, K fertilizer and straw reduce the proportion of mineral K and improve proportion of other forms of potassium in the two locating sites. Compared with the beginning of orientation, temporal variability character of soil K content and proportion showed a difference between the two soil types; furthermore, there was a decrease in the content of mineral K and total K simultaneously in the two locating sites. As a whole, the effect of K fertilizer applied to soil directly excelled to wheat straw to soil. Wheat straw to soil was an effective measure to complement potassium to increase crop yield and retard the decrease of soil K.

Regional Evaluation of Winter Rapeseed Response to K Fertilization, K Use Efficiency, and Critical Level of Soil K in the Yangtze River Valley

The investigation was carried out to study the response of winter rapeseed to potassium （K） feritlization and the critical soil available K level for current winter rapeseed production in the Yangtze River Valley （YRV） of China. A total of 132 field experiments were conducted in fields of farmers in the major winter rapeseed growing areas in YRV in 2000/2001 and 2004/2005 to 2006/2007 during growing season. Results of these field experiments showed that the average rapeseed yield increment resulting from 100 kg K ha-1 application was 358 kg ha-1, an increase over the control CK （no K） of 18.0% in 2005/2006 and 2006/2007. The average internal use efficiency （IE） of K was higher in the CK treatment （21.9 kg grain, kg-1 K uptake） than in the ＋K （100 kg K ha-1） treatment （17.7 kg grain, kg-1 K uptake）. Winter rapeseed required 68.1 kg of K to produce 1 000 kg seed. The recovery efficiency of K fertilizer in rapeseed production averaged 39.3%. The K balance was negative, with an average net removal of 117.6 kg K ha-1 in the CK treatment annually, and 56.8 kg K ha-1 in the ＋K treatment. The results indicated that there was a significant negative relationship between yield increments by K application and soil available K content. Based on the relative yield of CK/＋K at 90% level, the critical level of soil available K （NH4OAc-extractable K） was 135 mg kg-1.

砒砂岩覆土区典型小流域土壤可蚀性K值空间变异特征

[目的]研究砒砂岩覆土区典型小流域土壤可蚀性的空间变异特征,为砒砂岩覆土区土壤侵蚀机理深入探究和土壤侵蚀有效防治提供科学依据。[方法]以内蒙古准格尔旗砒砂岩覆土区二老虎沟小流域为研究对象,采集0—10 cm和10—20 cm土层共144份土壤样品,基于EPIC模型估算土壤可蚀性K值,并利用GIS和地统计学方法分析土壤可蚀性K值空间变异特征。[结果](1)二老虎沟小流域土壤砂粒、粉粒、黏粒和有机碳均呈中等变异程度,除黏粒和有机碳为中等空间自相关性外,其他土壤属性均呈弱空间自相关性。(2)小流域土壤可蚀性K值介于0.018 7~0.047 6 t·hm^(2)·h/(hm^(2)·MJ·mm),0—10 cm和10—20 cm土层K值变异系数分别为15.5%和20.3%,属中等变异强度;0—10 cm土层K值主要受随机性因素影响,呈弱空间自相关性,而10—20 cm土层受随机性因素和结构性因素共同影响,为中等空间自相关性。(3) 3种克里格插值方法结果表明:小流域土壤可蚀性K值空间变异受海拔和坡度影响明显,其总体分布趋势为西部和东南部较高、中部及偏东部较低;普通克里格插值方法较适宜应用于砒砂岩覆土区小流域,其估算结果可较好地显示土壤可蚀性的整体和局部两方面的空间变异特征。(4)在垂直空间变异上,0—10 cm和10—20 cm土层土壤可蚀性K值总体分布规律相似,但10—20 cm土层土壤可蚀性K值较0—10 cm土层空间变异更为明显。[结论]海拔和坡度对砒砂岩覆土区典型小流域土壤可蚀性K值空间变异影响明显,未来应优先对坡面和坡顶区域进行土壤侵蚀防治。

Kinetics of K Desorption from Soils in a Constant Electric Field (Electro-Ultrafiltration) and Its Application

Kdesorption from soils in a constant electric field(field strength:44.5Vcm-1) by means of electro-ultrafil-tration (EUF) followed second-order kinetics and could be described by the equation dd/dt = k(D-d)2. From theequation, such kinetic parameters relating to K desorption from soils as the maximum desorbable quantity D, quantity of K desorbed within 40 minutes d40, initial desorption rate Vo, desorption rate constant k and half-time t1/2 could be calculated. An expression which describes the relationships between the kinetic parameters on the one hand and the responses of barley to fertilizer-K in the field experiments in different sites and the potassium-supplying power of soils on the other was established. Vo, D and d40 were significantly correlated with barley relative yield, K uptake by barley and the content of soil available potassium. The rate constants of K desorption varied between 4.42 × 10-4-1.80 × 10-3kg mg-1 min-1 and highly correlated with the relative yield of barley. The kinetic parameters including Vo, D, d40 and k were successfully used to estimate the K-supplying power of soils.

Optimization of constitutive parameters of foundation soils k-means clustering analysis

The goal of this study was to optimize the constitutive parameters of foundation soils using a k-means algorithm with clustering analysis. A database was collected from unconfined compression tests, Proctor tests and grain distribution tests of soils taken from three different types of foundation pits： raft foundations, partial raft foundations and strip foundations. k-means algorithm with clustering analysis was applied to determine the most appropriate foundation type given the un- confined compression strengths and other parameters of the different soils.

Detection of K in soil using time-resolved laser-induced breakdown spectroscopy based on convolutional neural networks

One of the technical bottlenecks of traditional laser-induced breakdown spectroscopy(LIBS) is the difficulty in quantitative detection caused by the matrix effect. To troubleshoot this problem,this paper investigated a combination of time-resolved LIBS and convolutional neural networks(CNNs) to improve K determination in soil. The time-resolved LIBS contained the information of both wavelength and time dimension. The spectra of wavelength dimension showed the characteristic emission lines of elements, and those of time dimension presented the plasma decay trend. The one-dimensional data of LIBS intensity from the emission line at 766.49 nm were extracted and correlated with the K concentration, showing a poor correlation of R_c^2?=?0.0967, which is caused by the matrix effect of heterogeneous soil. For the wavelength dimension, the two-dimensional data of traditional integrated LIBS were extracted and analyzed by an artificial neural network(ANN), showing R_v^2?=?0.6318 and the root mean square error of validation(RMSEV)?=?0.6234. For the time dimension, the two-dimensional data of time-decay LIBS were extracted and analyzed by ANN, showing R_v^2?=?0.7366 and RMSEV?=?0.7855.These higher determination coefficients reveal that both the non-K emission lines of wavelength dimension and the spectral decay of time dimension could assist in quantitative detection of K.However, due to limited calibration samples, the two-dimensional models presented over-fitting.The three-dimensional data of time-resolved LIBS were analyzed by CNNs, which extracted and integrated the information of both the wavelength and time dimension, showing the R_v^2?=?0.9968 and RMSEV?=?0.0785. CNN analysis of time-resolved LIBS is capable of improving the determination of K in soil.

Effects of Long-term K Fertilizer Application on the Crop Yield and K Distribution of Soil Aggregates in a Paddy-Upland Rotation System

[Objective]A long-term paddy-upland experiment was conducted to evaluate the effects of the recommended amount of potassium( K)fertilizer on crop yield,distribution of soil aggregate,and soil available K content. It was mainly to ascertain the distribution of K in the soil aggregate components in the paddy-upland rotation system,and then to provide theoretical basis for soil structure improvement,K pool management,and reasonable application of K fertilizer. [Method]There were 2 treatments selected,namely,NP(-K) treatment and NPK( + K) treatment in this study. Then the effects of K fertilizer application on the yield,available K content,and aggregate distribution in the middle rice-winter rape rotation system were analyzed. [Result]The results showed that the output of the crop rotation was affected by the year and fertilization. Compared with NP(-K),the average yield increases of rice and winter rape after application of K fertilizer were 0.51 and 0.33 t/hm2,with the increments of 7.5%and 14. 1% respectively. The long-term application of K fertilizer( 7 a) had no significant effects on the distribution of soil aggregates but could significantly increase the water-soluble K content and available K content at depths of 20-30 and 30-40 cm,and available K content of aggregates in each particle size. In addition,the balance of available K at the 10-20 and 30-40 cm of soil layers was the most significant through calculation of surplus-deficit value of available K in agglomerates of different soil layers. [Conclusion]Compared with the initial available K content in the farmland in 2011,the current K fertilizer application could lead to that farmland K content continues to decline. Therefore,we should pay attention to straw returned and supplement of organic K fertilizer,to maintain crop rotation system's productivity and soil K balance.

Potassium forms in calcareous soils as affected by clay minerals and soil development in Kohgiluyeh and Boyer-Ahmad Province,Southwest Iran

Potassium（K） is known as one of the essential nutrients for the growth of plant species. The relationship between K and clay minerals can be used to understand the K cycling, and assess the plant uptake and potential of soil K fertility. This study was conducted to analyze the K forms（soluble, exchangeable, non-exchangeable and structural） and the relationship of K forms with clay minerals of calcareous soils in Kohgiluyeh and Boyer-Ahmad Province, Southwest Iran. The climate is hotter and drier in the west and south of the province than in the east and north of the province. A total of 54 pedons were dug in the study area and 32 representative pedons were selected. The studied pedons were mostly located on calcareous deposits. The soils in the study area can be classified into 5 orders including Entisols, Inceptisols, Mollisols, Alfisols and Vertisols. The main soil clay minerals in the west and south of the study area were illite, chlorite and palygorskite, whereas they were smectite, vermiculite and illite in the north and east of the province. Due to large amount of smectite and high content of organic carbon in soil surface, the exchangeable K in surface soils was higher than that in subsurface soils. It seems that organic matter plays a more important role than smectite mineral in retaining exchangeable K in the studied soils. Non-exchangeable K exhibited close relationships with clay content, illite, vermiculite and smectite. Although the amount of illite was the same in almost all pedons, amounts of structural and non-exchangeable K were higher in humid regions than in arid and semi-arid regions. This difference may be related to the poor reservoir of K~＋ minerals like palygorskite and chlorite together with illite in arid and semi-arid regions. In humid areas, illite was accompanied by vermiculite and smectite as the K~＋ reservoir. Moreover, the mean cumulative non-exchangeable K released by CaCl_2 was higher than that released by oxalic acid, which may be due to the high buffering capacity resulting from high carbonates in soils.

Kinetic analysis of soil contained pyrene oxidation by a pulsed discharge plasma process

A pulsed discharge plasma（PDP） reactor with net anode and net cathode was established for investigating the pyrene degradation in soil under different pulse peak voltage,air flow rate,pyrene content in soil,initial p H value and initial water content of the soil.Pyrene oxidation within the 60 min discharge time was fitting according to the pseudo-first order equation and the corresponding reaction kinetics constants（k values） were calculated.The obtained results show that pyrene oxidation under all the different reaction conditions obeyed the pseudo-first order equation well.Higher pulsed peak voltage and appropriate air flow rate were in favor of the increase of reaction rate of pyrene oxidation.A higher k value could be achieved in the lower initial pyrene content（the value was 100 mg kg^-1）.The k value of pyrene oxidation in the case of p H=4 was 11.2 times higher than the value obtained under the condition of p H=9,while the initial water content of the soil also has a large effect on the oxidation rate of pyrene due to the effect of PDP.

基于小流域尺度的土壤可蚀性K值空间变异

采用传统统计学和地统计学相结合的方法,以邓下小流域为研究区,利用EPIC模型中土壤可蚀性K值算法,研究了小流域尺度下土壤可蚀性K值空间变异特征及不同植被类型对其影响。结果表明:(1)研究区K值的变化范围为0.1498～0.4981,均值为0.3316,变异系数为22.11%,小流域土壤可蚀性存在中等程度的空间变异性。(2)研究区土壤可蚀性K值总体分布趋势是从西北向东南增大,条带状分布明显,K值较高处以"岛状"嵌于小流域中南部。北部森林覆盖区土壤抗侵蚀能力较强,中南部耕作种植及居住生活区土壤抵抗侵蚀能力较弱。(3)研究区8种不同植被类型除旱耕地外,K值垂直变异特征均是K0～20cm<K20～40cm<K40～60cm,土壤可蚀性随土壤垂直剖面深度增大而增大,土壤表层(0～20cm)抗侵蚀性能力最强。8种不同植被类型土壤表层K值(K0～20cm)的大小顺序为:休闲地>茶园>旱耕地>草地>阔叶林>灌木林>针叶林>毛竹林。

中国亚热带土壤可蚀性K值预测的不确定性研究

土壤可蚀性K值是土壤侵蚀模型(如USLE和RUSLE)的必要参数,直接套用经验模型估算土壤可蚀性K值会给土壤侵蚀预报带来不可估计的误差。本文以我国亚热带7种典型土壤可蚀性K值的观测值为依据,选用平均绝对误差(MAE)、平均相对误差(MRE)、均方根误差(RMSE)和精度因子(Af)四种数学统计项为指标,评价了诺谟图模型、修正诺谟图模型、EPIC模型、几何平均粒径模型和Torri模型等5种土壤可蚀性K值预测模型的不确定性。结果表明,5种模型的不确定性从小到大的顺序为:Torri模型<修正诺谟图模型和诺谟图模型<EPIC模型<几何平均粒径模型;Torri模型的MRE为0.291,不确定性依然很大。但经优化的Torri模型,可将土壤可蚀性K值预测的不确定性降至最低,其K的预测值与观测值的线性回归系数b=1.028(R2=0.921,p<0.01),MRE仅为0.120,可用于预测我国亚热带地区某些土壤可蚀性K值。

我国籽实和饲草燕麦土壤钾素丰缺指标与推荐施钾量初步研究

为了给我国燕麦测土施钾提供科学依据,本研究采用“零散实验数据整合法”和“养分平衡-地力差减法新应用公式”,开展了我国燕麦土壤钾素丰缺指标与推荐施钾量研究。结果表明,我国燕麦土壤速效钾第1~3级丰缺指标依次为≥258、117~258和<117mg/kg,全钾第1~4级丰缺指标依次为≥31、21~31、11~21和<11 g/kg。当钾肥当季利用率40%~60%时,目标产量1.5~6.0t/hm^(2)籽实燕麦第1~4级土壤推荐施钾量分别为0、10~60、20~120和30~180kg/hm^(2);目标产量4.5~15t/hm^(2)饲草燕麦第1~4级土壤推荐施钾量依次为0、18~90、36~180和54~270kg/hm^(2)。本研究初步建立了我国籽实和饲草燕麦土壤钾素丰缺指标推荐施肥系统,为我国燕麦测土施钾奠定了科学基础。

太湖流域苏皖汇流区土壤可蚀性K值及其应用的研究

利用土壤普查成果中的土壤图和理化分析等资料 ,采用公式计算法研究了该区土壤的可蚀性K值 ,改进和完善了K值图编制方法 ,并用微机首次制出具有准确几何位置、可与地形图配准的土壤可蚀性K值图。同时 ,还依据该区K值的分布特点讨论了它在水土保持、土壤年流失量监测、生态农业建设和防洪减灾中的应用。

三峡库区土壤可蚀性K值研究

研究土壤可蚀性K值有助于宏观判断和定量分析三峡库区土壤侵蚀的特点。依据重庆市和湖北省的第2次土壤普查资料,建立三峡库区各土种的理化性质数据库,并通过三次样条插值方法对不同粒径标准的土壤质地进行转换,然后采用几何平均粒径模型修正公式计算出三峡库区各土种的可蚀性K值,经面积加权平均得到三峡库区11类土壤的可蚀性K值,最后在分类分级基础上,探讨土壤可蚀性K值的分布特征。结果表明：三峡库区土壤可蚀性K值变化于0.007 2-0.019 2 t.hm^2.h/（MJ.mm.hm^2）之间,其中在0.015 0-0.019 0 t.hm^2.h/（MJ.mm.hm^2）之间的中高可蚀性和高可蚀性土壤面积占库区总面积的74.49%;三峡库区存在很大的土壤侵蚀风险,国外已有的K值经验算式不能直接照搬,而采用几何平均粒径修正模型对三峡库区土壤可蚀性K值进行估算是可行的。

钾镁供应浓度及比例对温室土壤K-Mg吸附特性的影响

不同钾、镁浓度及摩尔比供应对大田及温室土壤K+,Mg2+离子吸附特性影响的研究结果表明:大田及温室土壤对K+,Mg2+离子的吸附量均随其供应浓度和比例的增加而增加,日光温室栽培下土壤对K+的吸附量显著小于大田土壤;K+/Mg2+为2∶1时不同土壤对Mg2+离子吸附量的差异均较小,K+/Mg2+为1∶1时,温室塿土Mg2+的吸附量低于大田土壤,而潮土温室和相应大田土壤间的差异较小;随供应的K+浓度和比例升高,土壤对Mg2+离子的吸附量显著降低。随K+,Mg2+离子浓度提高,大田土壤K+吸附率均呈对数趋势下降,而温室土壤K+吸附率呈对数趋势增加;不同K+/Mg2+对大田土壤K+吸附率影响较小,而温室土壤在K+/Mg2+大时K+吸附率较大;不同土壤对Mg2+的吸附率随K+,Mg2+离子浓度变化未表现明显的规律性。随着K+,Mg2+离子总浓度的增加,土壤中Ca2+离子的解析量呈直线增加,不同K+/Mg2+对Ca2+离子解析量影响的差异较小,温室土壤Ca2+离子解析量大于大田土壤。

用田间实测法研究我国亚热带土壤的可蚀性K值

本文在自然降雨条件下用全裸地小区田间实测了我国亚热带七种有代表性的不同类型土壤的可蚀性K值，结果表明这七种不同类型土壤间的K值差别很大，其中紫色土和红砂岩发育的耕种普通红壤的K值最大，分别达到0．440和0．438，最小的是第四纪红色粘土发育的红色土，其值只有0．104，还不到紫色土K值的1／4。我们亦用国际上十分流行的诺谟图方法估算了这七种不同类型土壤的可蚀性K值，其中有二类土壤用这种方法所估算的K值较接近于田间实测的K值，有一类土壤相差较大，有三类土壤相差很大，还有一类土壤不能用这种方法来估算，因此，国际上十分流行的用诺谟图估算土壤可蚀性K值的方法对我国亚热带多数土壤并不合适。

小流域尺度土壤可蚀性(K值)的变异及不同采样密度对其估值精度的影响

以观音寺小流域为例,通过高密度采样,利用EPIC模型中土壤可蚀性K值计算公式计算了可蚀性K值,并运用逆距离加权插值方法生成了研究区的K值分布图。经典统计学方法分析表明,在小流域尺度下土壤可蚀性K值存在很强的空间变异性,其变异系数达39.94%。因此,定量监测、评价流域水土流失时,K值的这种空间变异性不能忽略。对不同采样密度下K值空间估值精度的评价表明,当采样点数目均匀地减少一半时,即4个/km2的样点密度下,K值估计误差仍然可以控制在25%以内。

土壤可蚀性K值的计算和K值图的制作方法研究—以南京市方便水库小流域为例

本文介绍了土壤可蚀性K值的计算和K值图的制作方法。涉及利用公式法计算该区的土壤可蚀性K值的参数设置方法,和运用地统计学的协同克里格空间插值的方法进行K值图的编制方法,并对K值图在水土保持、水土流失定量监测、生态与环境等方面的应用作了简要说明。

长江以南东部丘陵山区土壤可蚀性K值研究

以土壤亚类为基础，从土种入手，依据第二次土壤普查资料建立了我国东部丘陵区各土种的理化性质数据库。应用土壤可蚀性方法，计算出各土种的土壤可蚀性Ｋ值，用面积进行加权平均，经分类分级后，连续到相应的土壤图上，得到我国东部丘陵区土壤可蚀性Ｋ值图及其分布规律。

东北近天然林土壤可蚀性K值研究

基于吉林省汪清林业局所辖林场10块近天然林样地,采集0—20,20—40和40—60cm土层土壤样品,对土样进行了粒径分析及养分测定。运用侵蚀—土地生产力影响评估模型（EPIC）对研究区土壤可蚀性因子K值进行了估算,分析讨论了K值的影响因素及其与土壤养分之间的相关性。结果表明,研究区内土壤可蚀性K值平均为0.060 7t·hm2·h/（MJ·mm·hm2）;0—20cm深度的土壤可蚀性K值较20—60cm土层土壤大,针阔混交林的K值比阔叶混交林的大;当林分密度小于1 200株/hm2,郁闭度小于0.75时,K值随林分密度和郁闭度的增大而减小。K值与土壤养分的相关性由高到低依次为：全氮〉速效钾〉有效磷〉全磷,除全氮外其他土壤养分均与K值呈负相关。最适林分密度为750~1 200株/hm2,在该密度下各土壤养分含量状况较好且土壤抗蚀能力较高。