施磷对玉米吸磷量、产量和土壤磷含量的影响及其相关性

为了给玉米磷高效利用提供理论依据, 在低磷土壤(Olsen-P 4.9 mg·kg^-1)上, 通过田间试验, 研究了施磷0(T₀)、50 kg(P₂O₅)·hm^-2(T₁)、100 kg(P₂O₅)·hm^-2(T₂)、200 kg(P₂O₅)·hm^-2(T₃)、1 000 kg(P₂O₅)·hm^-2(T₄)对两个玉米品种"鲁单9002" (LD9002)、"先玉335"(XY335)的产量、磷素吸收利用及根际磷动态变化的影响。结果表明: 两玉米品种根际土、非根际土速效磷含量在不同生育时期都表现为T12O₅)·hm^-2的T₃处理非根际土转化为根际土土壤磷的量最大, 同时玉米生物量、产量、磷转移量也达到最高, 而施磷1 000 kg(P₂O₅)·hm^-2处理玉米生物量、产量与中磷水平相比没有显著增加, 但植株吸磷量较高。XY335的花后磷转移量小于LD9002。相关分析表明, LD9002根际土、非根际土速效磷含量与茎、叶吸磷量之间显著相关, 以播种后79 d与茎、叶磷浓度、吸磷量、生物量、产量之间的相关系数最高; 而XY335根际土、非根际土速效磷含量与茎、叶磷浓度之间显著相关, 在播种后47 d期间与茎、叶磷浓度、吸磷量、生物量、产量之间的相关性最好。因此, 在低磷土壤上, LD9002和XY335分别在播种后79 d和47 d时是植株对磷的敏感期, 可以通过测试根际土、非根际土速效磷含量来反映土壤的供磷状况; LD9002在79 d时最大吸磷量需要的根际土、非根际土速效磷含量分别为54.95 mg·kg^-1、32.99 mg·kg^-1, XY335品种在47 d时最大吸磷量需要的根际土、非根际土速效磷含量分别为51.24 mg·kg^-1、35.35 mg·kg^-1; 施磷量1 000 kg(P₂O₅)·hm^-2处理两品种玉米产量、生物量、磷积累量与施磷量100~200 kg(P₂O₅)·hm^-2处理没有显著差异。     

黄土丘陵区不同类型农地的养分循环平衡特征

该文以黄土丘陵沟壑区的安塞试验站长期肥料定位试验的实测资料为研究对象，定量研究川地、坡地、梯田不同类型农地养分循环特征。研究结果表明：川地、坡地、梯田与农民习惯施肥水平相类似的处理，年养分盈亏量分别是：川地每年每hm²氮素盈余10.2 kg，P₂O₅盈余56.6 kg；坡地每年每hm²氮素亏损7.0 kg，P₂O₅亏损14.7 kg；梯田每年每km²氮素盈余104.9 kg，P₂O₅盈余107.3 kg。退耕还林和实施“坡改梯”工程是黄土丘陵沟壑区农地养分循环不断朝良性方向发展的关键措施。     

施肥对旱地冬小麦水分利用效率的影响

据陕西省长武县旱塬冬小麦肥料实验资料,分析了冬小麦的水肥与产量关系。结果表明,作物耗水量、水分利用效率、底墒利用率与产量关系密切;施肥方式、种类和数量均直接影响水分利用效率和底墒利用率;注重肥料配合施用,适当增施有机肥、N肥和P₂O₅能明显改善水分利用效率和底墒利用率。N、P₂O₅比例对土壤水分利用表明,N肥有利于提高水分利用效率,P₂O₅则有利于提高底墒利用率和增加对土壤深层水的利用.     

磷灰石的结晶性质与磷矿粉肥效相关性的研究

本文研究了磷灰石的结晶性质,包括CO₃^2-与PO₄^3-的置换量、a₀、c₀、Da₀、Dc₀和CO₂指数,和磷矿粉直接施用肥效的相关性。结果表明,101个磷灰石的晶格中,CO₂%的变幅为3.62-0.04%;a₀为9.331-9.380A;c₀的变幅比较小;Da₀为391-2242A;Dc₀为424-2000A;CO₂指数为0.000-0.493。磷矿粉肥效与磷灰石结晶参数的相关阵表明,CO₂置换量的多少与磷灰石的组成最为相关(r=0.999)。这是氟磷灰石被碳酸根置换后形成碳氟磷灰石的理论依据。同时,CO₂与a₀、Da₀和Dc₀均呈极显著的负相关。逐步回归分析表明,上述各个参数中,对磷矿粉增产起主导作用的是Da₀和Dc₀,即最能评价磷矿粉肥效高低的是磷灰石晶粒的比表面大小。2%柠檬酸直接浸提原磷矿时,受到磷矿中伴生的碳酸盐矿物的干扰,其中方解石的干扰显著大于白云石。对于提纯的磷矿,由于碳酸盐的干扰已经消除,因而其与磷矿粉肥效的相关系数的可靠性可以提高到2倍左右。     

旱地麦田水肥关系及对产量的影响试验研究

用微区隔离遮雨棚法研究结果分析回归得出，氮肥用量、磷肥用量、供水量与冬小麦产量之间关系。固定肥料用量，在试验供水范围内水分和小麦产量呈近似直线关系；固定供水量，施肥量和小麦产量呈抛物线关系。氮肥用量和供水量之间有明显的正交互作用，磷肥用量与供水量之间交互作用不明显。大田不同降雨年份试验结果表明，施肥增产效果是降雨多＞降雨中＞降雨少的年份，在蓄墒期、生育期降雨量为355、411和523 mm的低、中、高降雨年份，冬小麦达最高产量时的氮、磷肥用量分别为每hm²施N 64.5 kg、P₂O₅52.5 kg；N 27.5 kg、P₂O₅105.0 kg和N 192.0 kg、P₂O₅157.5 kg。     

施磷水平对晋南旱地冬小麦产量及磷素利用的影响

在自然降水条件下, 通过大田试验研究了施磷量对晋南旱地冬小麦部分抗性指标、产量、磷素利用率以及1 m土壤磷素形态分布特征的影响。结果表明: 施磷可以提高旱地冬小麦抗逆性、穗数, 进而提高产量, 但对穗粒数和千粒重影响不明显。在0~120 kg(P₂O₅)·hm^-2施磷范围内, 小麦生育期旗叶硝酸还原酶(NR)活性、穗数和产量随施磷量增加显著增加, 丙二醛(MDA)和脯氨酸(Pro)含量随施磷量增加显著降低。当施磷量达到180 kg(P₂O₅)·hm^-2时, 旗叶中MDA、Pro含量降低幅度较小, 甚至会升高; NR活性除抽穗期外不再有显著变化, 穗数和产量变化亦不显著。磷素施入土壤后易固定, 导致磷肥利用率偏低, 当季回收率仅为9%~13%, 以施磷60~120 kg(P₂O₅)·hm^-2为最高。1 m土壤各土层Hedley形态磷分布特征表现为: HCl-Pi>Residual-P> HCl-Po>NaOH-Pi>NaHCO₃-Pi>NaOH-Po>H₂O-Pi>NaHCO₃-Po>H₂O-Po, 其中以HCl-P和Residual-P为主, 分 别占全磷的75%和20%左右, H₂O-P、NaHCO₃-P和NaOH-P含量共占全磷的5%左右。施入土壤中的磷素当 季主要被固定在0~20 cm土层, 不同Hedley形态磷增加量总体在0~39.11 mg·kg^-1之间, 且施磷越多, 被固定磷素就越多。综合考虑冬小麦抗逆性、产量及磷素利用率, 当地旱作冬小麦施磷量(P₂O₅))以120 kg·hm^-2左右为宜。     

应用回归设计寻求早稻最佳施肥方案

衡阳市的熟红黄泥水稻土含氮、磷元素较丰富,钾素相对缺乏:有机质为3.9%,全氮为0.20%,水解氮196ppm,全磷(P₂O₅)0.17%,速效磷(P₂O₆)25ppm,全钾(K₂O)1.18%,速效钾(K₂O)60ppm。     

不同肥料用量和配比对西瓜产量、品质及养分吸收的影响

为探索西瓜的适宜施肥量和养分配比, 通过田间试验, 研究了不同肥料用量和配比对西瓜产量、品质及养分吸收的影响。结果显示: 与习惯施肥处理相比, 减氮磷钾处理的西瓜产量、Vc含量分别增加0.77%、17.18%, 还原糖含量、硝酸盐含量分别减少12.56%、27.94%; N、P₂O₅、K₂O养分总量相同、比例不同的3个处理间相比, 减氮磷增钾处理的西瓜产量、Vc含量、还原糖含量均最高, 硝酸盐含量最低; 习惯施肥、减氮 磷钾、减氮磷、减氮磷增钾4个处理的西瓜秧中N、P₂O₅、K_{2O含量比例分别为: 1︰0.18︰2.26、1︰0.22︰2.66、1︰0.26︰2.75、1︰0.19︰2.46; 西瓜皮中N、P2O5、K2O含量比例分别为: 1︰0.34︰2.78、1︰0.34︰2.60、 1︰0.30︰2.37、1︰0.29︰2.14。综合考虑各项指标, 在本试验条件下, 施肥总量比习惯施肥量减少36%、N︰P2O5︰K2O为1︰0.41︰1.28是西瓜最优施肥处理。}     

施肥对青岛市设施蔬菜产量、净产值及土壤环境的影响

为进一步提高设施蔬菜的施肥效率, 减少肥料成本和对环境的污染, 对青岛市设施蔬菜施肥状况及其对产量、净产值和土壤环境的影响进行了研究。结果表明, 设施黄瓜和番茄氮、磷、钾肥施用均明显过量。黄瓜N、P₂O₅、K₂O年施用量分别为1 841.5 kg·hm^-2、864.0 kg·hm^-2和1 978.7 kg·hm^-2, 番茄N、P₂O₅、K₂O年施用量分别为1 436.7 kg·hm^-2、833.6 kg·hm^-2和1 643.7 kg·hm^-2。施肥中有机/无机肥料养分比例较为合理, 重视了有机肥的施用。年度施用N、P₂O₅、K₂O量及其总量对年度蔬菜产量、净产值有明显影响, 存在着线性方程关系。随着年度施氮量的增加, 土壤NO₃^--N含量明显增加, 31.4%的农户设施蔬菜田土壤NO₃^--N含量居高和较高水平。土壤速效磷含量随年度施磷量的增加而增加, 74.3%的农户设施蔬菜田土壤速效磷为高水平。68.6%的农户设施蔬菜田土壤为酸性和微酸性, 有向酸性发展的趋势。生产中应适量减少氮、磷和钾肥投入, 推广测土配方施肥、水肥一体化、秸秆生物处理等技术, 促进青岛市设施蔬菜生产的可持续发展。     

鸡分腐解过程腐殖质络合态铜的变化及其淋溶特征

Chicken manure was composted for 110 d to evaluate changes in organic carbon (C) and humic substance-complexed copper (HS-Cu) extracted with water, sodium hydroxide (NaOH), and sodium pyrophosphate and sodium hydroxide mixture (Na₄P₂O₇-NaOH). The average HS-Cu content from the Na₄P₂O₇-NaOH extraction accounted for 46.8% of the total Cu in the compost, followed by those from the NaOH and water extractions, which accounted for 34.5% and 6% of the total Cu in the compost, respectively. NaOH-Na₄P₂O₇-extractable HS-Cu increased throughout the composting process. NaOH-extractable HS-Cu increased during the first 50 d of composting and then leveled off. Water-extractable HS-Cu enhanced during the first 21 d and then decreased. Water-extractable HS-Cu was not correlated to NaOH-or NaOH-Na₄P₂O₇-extractable organic C. The average amount of Cu leached from the compost was about 20% of the total Cu in the chicken manure and Cu leaching increased during the first 35 d of composting and then decreased. Leaching of Cu was significantly correlated to the concentrations of HS-Cu extracted with NaOH and water, but was not correlated to the concentration of HS-Cu extracted with NaOH-Na₄P₂O₇. Thus, NaOH-and water-extractable HS-Cu were relatively labile and NaOH-Na₄P₂O₇-extractable HS-Cu was relatively immobile. Composting process after rapid decomposition could result in low potential of Cu leaching because of formation of more NaOH-Na₄P₂O₇-extractable HS-Cu.     

Extraction of phosphorus,potassium, calcium,and magnesium from soils by an ion‐exchange resin procedure

Abstract

A procedure for the simultaneous extraction of phosphorus, potassium, calcium and magnesium from soils, by an ion‐exchange resin procedure applicable to large‐scale advisory soil testing, is described. The important steps are the disaggregation of soil by shaking in water during 15 minutes with a glass marble, the transference of the elements from the soil to a sodium bicarbonate treated mixture of anion and cation exchange resins during a 16‐hour shaking period, the separation of the resin from the soil by sieving and extraction of the elements from the resin.

The results of resin extractable calcium, magnesium and potassium were comparable to the results of these elements extracted with 1M NH₄OAc, to calcium and magnesium extracted with 1M KCl, and to potassium extracted with 0.025M H₂SO₄.

For phosphorus the resin extractable values were not comparable to the results obtained by the former routine method, based on the extraction with 0.025M H₂SO₄. The results of resin extractable P presented closer correlation with cotton response to phosphorus application in 28 field experiments (r = 0.85**) as compared with 0.025M H₂SO₄ extractable P (r = 0.68**), and also with P uptake by flooded rice in a pot experiment with eight lowland soil samples (r = 0.98**), as compared with extraction with 0.0125M H₂SO₄ in 0.050M HCl, for which the correlation was not significant. The reasons for the superiority of the extraction of P with the described procedure are discussed.     

普钙、磷矿中磷的螯溶-差示光度法测定的研究

本文介绍了螯溶-差示光度分析技术用于分析高含量磷的普钙、磷矿样品.提出螯溶反应的机理及其示意式,由测定条件试验得到了螯溶剂在螯溶条件下的极限浓度及其pH值.控制溶解液中柠檬酸溶液浓度,即可防止柠檬酸对钼黄显色的抑制影响,氟离子对钼黄显色的干扰由铝离子络合以消除.用酸溶螯溶-钼酸喹啉重量法作对比试验以及磷的回收试验,验证了螯溶-差示光度法的精密度和准确度.所获结果表明,与酸溶-钼酸喹啉重量法结果比较,含磷高的磷矿,本法的相对误差小于±1%;含磷较低的普钙,其相对误差约为±1.5%.磷的回收率均在99.0-100.4%之间.本法干扰少、无污染,节省设备、试剂,溶样手续简便快速,分析结果准确可靠.     

Agronomic evaluation of phosphate rock and slag on an upata acid soil in Bolivar State,Venezuela

Abstract

An agronomic evaluation of phosphate rock and slag on the acid soils of Upata, Bolivar State was conducted to measure their effect on the chemical properties of the soil and growth of Brachiaria decumbens. A field experiment was established using a split plot design with three replications. The treatments were, i) three sources of phosphate rock (Riecito and Lizardo of Falcon State and Monte Fresco of Tachira State) at four rates of P₂O₅/ha (0, 50, 100, and 200), ii) one source of high‐solubility P [triple superphosphate (TSP) at the same rates], and iii) three levels of calcium applied as basic slag from the Orinoco Steel Company (0, 300, and 600 kg Ca/ha). A basic fertilization was applied to all plots (217 kg/ha Urea, 50 kg/ha KCl, and 78 kg/ha magnesium sulphate). The pasture species used was Brachiaria decumbens. Pasture and soil samples were taken at 2, 3, 5, 7, 12, 14, 16, 17, 24, 27, and 31 months after planting. The pasture samples were analyzed for dry matter production (DM), and percentage content of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg). Soil samples were analyzed for pH, cation exchange capacity (CEC), and available calcium (Ca) and phosphorus (P). The relative agronomic effectiveness (RAE), calculated using the formula: RAE (%) = DM of the rock ‐ DM of the check plot/DM of TSP ‐ DM of check plot × 100 was applied for each harvest time. The best RAE values at each sampling time were obtained with the Monte Fresco phosphate rock at the rate of 200 kg P₂O₅/ha and 600 kg Ca/ha as slag. There was a tendency for the RAE value to improve with each sampling apparently due to the slow release of phosphorus from the phosphate rock and its residual effect. There are also values of RAE that show better dry matter production than the high soluble source of TSP.

Soil available P and Ca increased with phosphate rock and slag application from 5 and 200 mg/kg to 25 and 400 mg/kg, respectively, after 2.5 years of the experiment. Phosphorus uptake changed from 0.1% in the check plot, which is insufficent to supply the P requirement of grazing cattle in the tropics to a value higher than 0.2%, depending on the sampling time. Soil pH increased slightly from 5.2 to 5.6 with phosphate rock, and to 6.2 when basic slags were applied.     

Determination of phosphorus in calcareous soils by mehlich 3, mehlich 2, cal,and egner extractants

Abstract

Acid extractants were found to be a problem when determining phosphorus in some soils especially in soils with a higher content of carbonates. Carbonate content, soil pH or extractable calcium cannot exactly predict the behavior of a particular soil. On the other hand, measurement of pH after extraction reflects the ability of soil to change the properties of an extractant. The objective of this study was to find the relationships between pH changes during the extraction and the extraction of phosphorus for Mehlich 3, Mehlich 2, CAL, and Egner extractants. Twelve soil samples from various regions of the Czech Republic were taken for investigation. The pH/KCl of the samples was in the range 4.9–7.3. Calcium carbonate was added into the extracting bottles to the soil samples before extraction. The CaCO₃/soil ratio was from 0 to 0.5. The content of phosphorus and pH were measured in filtrates after extraction. The ratio P₁ =P_meas /P_O was calculated for all measurements, all additions of calcium carbonate and all soils. P_meas is the measured value of phosphorus after extraction with the addition of calcium carbonate and P_o is the value of phosphorus determined after the extraction without addition of calcium carbonate. The ratio P_r reflects the changes in the extractability of phosphorus and it is independent of the absolute content of phosphorus in soil. The relationships between P_r and pH after extraction for CAL, Mehlich 2, and Mehlich 3 extractants were found. No such relationship was found for Egner extractant. Correction equations (x=pH after extraction, y=P_r):     

不同形态磷肥的径流流失特征及其效应

采用野外径流小区方法研究不同形态磷肥的流失特征、流失量以及对氮钾元素的影响。结果表明,在磷的流失途径中,颗粒态磷(PP)占总磷(TP)流失量的61.6%～83.1%,是磷流失的主要途径;施用磷肥可以促进土壤对氮钾元素的保持能力,减少氮钾元素的流失;磷肥的施用提高了小油菜的产量,并促进了小油菜对氮钾元素的吸收;微晶化磷矿粉可以有效减少磷的流失,在等磷量下,微晶化磷矿粉中的磷流失量分别是过磷酸钙和钙镁磷肥的54.2%和69.4%。在一定范围内,随微晶化磷矿粉施用量的增加,磷的流失量增加,但流失率减小,对促进土壤保持氮钾能力及小油菜对氮磷钾元素的吸收越明显。     

Evaluation of Ammonium Bicarbonate–Diethylene Triamine Penta Acetic Acid as a Multinutrient Extractant for Acidic Lowland Rice Soils

Abstract

Simultaneous extraction of nutrients using ammonium bicarbonate–diethylene triamine penta acetic acid (ABDTPA) extractant has been successful for highland soils, but its potential for lowland soils is still uncertain. This study evaluated the suitability of ABDTPA extractant to determine available phosphorus (P), potassium (K), sodium (Na), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) in lowland rice soils of Sri Lanka. Available nutrients were analyzed both by conventional and ABDTPA methods, using the original ABDTPA (1∶2 soil–extractant) method as well as a modified (1∶4 soil–extractant) method. Conventional methods tested were Olsen, Bray 1, and FeO strip for available P; neutral NH₄OAc extraction for exchangeable Ca, Na, K, and Mg; and DTPA extraction for available Zn, Cu, Fe, and Mn. Nutrient content and uptake by plants were determined by a pot experiment with rice (Oryza sativa). Nutrients extracted by the conventional methods and ABDTPA methods correlated well, in general, for all nutrients. Highly significant correlations were observed between plant uptake and extractable nutrients by 1∶2 and 1∶4 ABDTPA methods for P (r=0.85***and 0.73***, respectively), K (r=0.79*** and 0.66***, respectively), Na (r=0.86*** and 0.78***, respectively), Zn (r=0.66*** and 0.60***, respectively), Mn (r=0.72*** and 0.84***, respectively), and Fe (r=0.74*** and 0.68***, respectively). Calcium and Mg extracted by ABDTPA showed a poor relationship with their respective plant uptake. The ABDTPA method was as effective as or even better than the conventional methods in evaluating fertility status of lowland rice soils with respect to most nutrients. Replacing the conventional methods by the single ABDTPA multielement extractant will reduce the time and cost of soil analysis.     

Soil Health and Soil Fertility Assessment by the Haney Soil Health Test in an Agricultural Soil in West Tennessee

The Haney Soil Health Test (HSHT) is a recent approach to quantify soil health by focusing mostly on soil biology. It uses a new extractant (H3A) for the extraction of plant available nutrients, a new method of soil respiration measurement (24-hr CO₂ burst) using Solvita® gel system, and a new approach in determining bioavailable carbon (C) and nitrogen (N) namely water extractable organic C (WEOC) and water extractable organic N (WEON). A soil health score is calculated by combining Solvita® respiration, WEOC, and WEON data. The objective of this study was to test the feasibility of HSHT to detect the management-induced changes in soil nutrient levels and soil health in the production systems of west Tennessee. We tested soils collected from a cover crop field trial established in 2013 on a no-till corn (Zea mays L.) – soybean [Glycine max (L.) Merr.] rotation. Compared to Mehlich-1 and Mehlich-3, H3A extracted the lowest amount of soil extractable phosphorus, potassium, calcium and magnesium. Neither the soil health score nor its component parameters showed significant differences between cover crop treatments and the control. In addition, the Solvita® CO₂ data did not provide a reliable estimation of potentially mineralizable N. Overall, the HSHT did not detect differences in soil health due to cover cropping in west Tennessee. We conclude that HSHT, though a promising concept due to its focus on linking soil biology with soil fertility and soil health, may need extensive field evaluation and refinement in contrasting soils and climates across the US.     

不同施磷水平对土壤中重金属镉的钝化效果评价

通过室内培养试验,以P/Cd摩尔配比分别为0,2∶3,3∶2,2∶1,4∶1进行了不同磷肥钝化修复Cd污染土壤试验。采用毒性淋溶提取法(TCLP)和形态分析法评价了磷酸氢二铵(DAP)、磷酸二氢钾(MPP)、过磷酸钙(SSP)和磷酸钙(TCP)对污染土壤中Cd的钝化效果。结果表明,4种磷肥的钝化效果依次为:MPPDAPSSPTCP,4种磷肥的钝化处理可显著降低土壤中TCLP提取态Cd含量,在磷肥剂量水平P/Cd为4∶1时对土壤中Cd的钝化效果最佳,最大降低幅度为49%;添加磷肥能够大幅度提高土壤中速效磷的含量,相同磷水平下,土壤中速效磷含量高低次序为:MPPDAPSSPTCP,TCLP提取态Cd含量随土壤速效磷含量升高而显著降低(R=-0.903**);DAP,MPP,SSP和TCP处理后交换态Cd的浓度降幅分别为23.75%,39.06%,16.60%和18.36%,而碳酸盐结合态(WSA)、铁锰氧化物结合态(Fe-Mn-OX)、有机结合态(OM)和残渣态(RES)Cd的含量均有所升高,表明磷素是通过改变Cd的存在形态而降低其有效态含量的。     

Effect of Grinding on Soil Extraction by Aqua Regia, 2 M Nitric Acid,and Mehlich 3

Abstract

The effect of grinding on soil extraction was determined for two soil fractions and three extractants. Arsenic (As), beryllium (Be), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), vanadium (V), and zinc (Zn) were extracted by aqua regia and 2 M nitric acid. Mehlich 3 extractant was used for determination of potassium (K), magnesium (Mg), calcium (Ca), phosphorus (P), iron (Fe), and aluminum (Al). One hundred forty‐seven agricultural soil samples representing all major soil types, climatic regions, and proportions of agronomic cultures in the Czech Republic were collected for the study. Particle size fractions smaller than 2 mm and smaller than 0.150 mm were chosen for investigation. Extraction of elements by aqua regia was similar for both size fractions of soil. Cold 2 M nitric acid is a weaker extractant than aqua regia, and a statistically significant increase in extractable Be (5%), Cd (6%), Co (11%), Cu (5%), Ni (5%), and V (2%) was measured with the finely ground soils. An increase for the finer fraction for K (10%) and Mn (25%) was found for Mehlich 3. A more complex nonlinear relationship was found for Mehlich 3 extractable Al and Fe. This was probably caused by a more intensive re‐adsorption of Fe and Al to the finely ground soils.     

硅钙钾镁肥及引入柠檬酸对红壤和潮土pH值及养分含量的影响

通过土壤培养试验研究了硅钙钾镁肥(SCPM)及引入柠檬酸的复混肥(CA-SCPM)在酸性红壤和石灰性潮土上的养分供给和酸碱度调节能力。硅钙钾镁肥添加量设置为6 g/kg,硅钙钾镁肥与柠檬酸(CA)的比例为88%∶12%。与对照处理相比,培养至150 d时,SCPM肥及CA-SCPM肥提高红壤pH值约1.16个单位,提高潮土pH值约0.19个单位。SCPM、CA-SCPM两个处理均能显著提高红壤速效钾、交换性钙镁、水溶性钙镁硅及有效硅含量;SCPM、CA-SCPM两个处理提高了潮土速效钾、有效硅及水溶性硅含量,却降低了潮土交换性钙镁、水溶性钙镁含量。CA对两种土壤养分有效性无明显影响。SCPM肥在红壤上的改良效果,体现在其提高pH值、盐基离子以及有效硅含量;在潮土上的积极效果主要表现在速效钾和有效硅含量的提高,将CA引入SCPM肥后综合效果更好。