硅钙包裹尿素对温室大棚菜地土壤养分的影响

通过不同用量硅钙包裹尿素与普通尿素对土壤养分的对比试验,研究了硅钙包裹尿素对温室大棚西葫芦菜地土壤养分的影响。试验结果表明:相同施肥条件下,硅钙包裹尿素处理的土壤速效钾、有效硅、水溶性钙和镁、有机质含量高于普通尿素处理,且随着硅钙包裹尿素施入量的增加而提高,最高值出现在施入量为0.224 kg/m2时;硅钙包裹尿素处理的速效磷含量优于普通尿素处理,其含量随硅钙包裹尿素施入量增加而降低;硅钙包裹肥对碱解氮起到了缓释效果,在生长后期含量较高,且随施肥量增加而提高。     

土壤磷素对作物产量及供磷能力的影响

多年多点试验研究表明 ,河西地区主要耕地 0～ 2 0 cm耕层有效磷平均含量 9.9mg/ kg,10 mg/ kg以下的农田占 5 6 .4% ,大于 15 mg/ kg的 19.5 % ,90 %的农田施磷增产 15 .0 %～ 2 6 .0 %。作物对土壤磷依存率在氮肥激发条件下为 6 8.1%～ 85 .9% ;无肥条件下 46 .1%～ 75 .8% ,供磷能力与土壤磷呈正相关。作物吸收的磷素 14.1%～ 31.9%由当季施肥供给 ,化肥磷素的当季利用率为 9.9%～ 17.6 %。     

不同用量腐植酸钾对果蔗产量和品质的影响

正以果蔗为研究对象,通过施用不同用量腐植酸钾,研究其对果蔗产量、品质及土壤特性的影响。结果表明,施用以木本泥炭为主要成分的腐植酸钾,可显著改善土壤的特性;随着腐植酸钾施用量的增加,土壤p H升高,土壤容重下降,土壤含水量提高,土壤碱解氮、速效磷含量升高。在与常规施肥等量钾的腐植酸钾施用量下,土壤容重比常规施肥     

科学施肥计算实例

化肥应用中出现的问题 ,并不是化肥本身所带来的 ,而是我国科学施肥水平不高造成的。据全国土壤普查结果表明 ,我国土壤施肥 ,m(N)∶ m(P2 O5)∶ m(K2 O)应为 1∶ 0 .5∶ 0 .4 ,而目前这一比例却为 1∶ 0 .4∶ 0 .17,出现施肥比例失衡。应遵循“六看”“三结合”的施肥原则。“六看”即 1看土壤施肥 ,2看作物施肥 ,3看气候施肥 ,4看苗棵施肥 ,5看肥料施肥 ,6看栽培目的施肥。“三结合”即 1有机肥与化肥结合 ,2底肥与追肥结合 ,3氮磷钾肥相结合。施肥上要多施复合肥 ,推广配方施肥 ,才能达到以氮促磷 ,以磷促钾 ,以钾促氮 ,相互促进的效应…     

磷的农业化学(Ⅱ)

作物生长需要的养分,主要是依靠土壤和肥料两种来源供给。在中等产量水平时,作物吸收的氮有３０％～６０％,磷有５０％～７０％,钾有４０％～６０％是靠土壤肥力提供。除极少数无土栽培和根外施肥外,化肥主要是通过土壤向作物提供养分,因此,土壤的物理化学性质对施肥效果特别重要。土壤学是介于地球科学与生命科学之间的一门独立的自然学科。本文从化肥生产者应具备的土壤基础知识出发,只撷取了其中的土壤物理（土壤三相、颗粒、质地、孔隙、水分、空气、温度）,土壤化学（土壤矿物、有机质、胶体、酸碱性）,土壤分类和土壤养分四部分作一简明扼要的介绍。     

磷的农业化学（II）

作物生长需要的养分，主要是依靠土壤和肥料两种来源供给。在中等产量水平时，作物吸收的氮有３０％～６０％，磷有５０％～７０％，钾有４０％～６０％是靠土壤肥力提供。除极少数无土栽培和根外施肥外，化肥主要是通过土壤和作物提供养分，因此，土壤的物理化学性质对施肥效果特别重要。土壤学是介于地球学与生命科学之间的一门独立的自然学科，本文从化肥生产应具备的土壤基础知识出发，只撷取了其中的土壤物理（土壤天相，质地，     

腐植酸钾对土壤微生物种类和数量的作用初探

本实验采用不同浓度的腐植酸钾处理纯培养条件下的烟草青枯菌,研究腐植酸钾对烟草青枯菌的抑制作用。同时将不同浓度的腐植酸钾施加入土壤,研究腐植酸钾对土壤微生物群的作用,为合理利用腐植酸钾来防治植物青枯病提供参考。     

几种确定作物施肥量的方法

确定作物施肥量是配方施肥技术中的核心问题。确定施肥量主要考虑作物产量、土壤供肥量和肥料利用率。介绍土壤养分分级法,目标产量配方法,田间试验法,氮、磷、钾比例法和经验施肥法确定施肥量的技术方法。     

吡喃草酮在不同类型土壤环境中降解行为

采用高效液相色谱法测定了吡喃草酮在田间和实验室条件下的降解规律,并对吡喃草酮在4种不同类型土壤中相关因素影响下的降解特性进行了研究.结果表明:吡喃草酮在田间条件下降解较快,半衰期为2～3 d;在实验室条件下降解较慢,半衰期为8～20 d.吡喃草酮在4种不同类型土壤中的降解速度,由快至慢依次为白浆土、草甸土、黑钙土和盐碱土.回归分析结果表明:吡喃草酮土壤中的降解与酸碱度和有机质含量有关,与阳离子交换量及速效钾相关性较差.根据吡喃草酮在田间和实验室条件下降解测定的结果判断,其对土壤残留污染的可能性极低.     

土壤氮素养分对土壤供氮能力及氮肥效应的影响

118个基点的随机试验表明,河西地区平川灌区耕层土壤碱解N 90 mg/kg以上的农田占38.4%;70～90 mg/kg的农田占37.7%;50～70 ng/kg的农田占17.5%;50 mg/kg以下的农田6.1%.土壤N素养分比较丰富.土壤供N效率平均为55.3～118.9 kg/hm;作物对N素依存率平均为39.1%～71.0%;土壤N对产量贡献率为48.6%～79.4%,三者均与土壤含N量呈正相关关系.肥料N利用率平均为27.0%～47.7%,与土壤N量呈负相关性.     

腐植酸对设施土壤的养分、盐分及番茄产量和品质的影响研究

试验选择具有10年棚龄的北方大棚,在不同施肥条件下,分别对土壤养分、盐分及番茄产量和品质等进行了研究,具体对因处理不同而引起的土壤养分与水溶性盐分含量、盐基离子组成的变化以及番茄的维生素C（Vc）含量和含糖量等进行了分析。结果表明,腐植酸含有多种物质,它的施用可以提高土壤有机质含量,并且能增加土壤速效态P、K的含量,降低土壤电导率。施用复混肥的土壤电导率增加37％,而施用腐植酸可以使土壤电导率降低10．4％。土壤盐基离子含量的增加,主要是由水溶性NH4^＋、K^＋、Ca^2＋、Mg^2＋含量的增加引起的。腐植酸由于含有各种官能团,可以有效抑制土壤中水溶性K^＋、Ca^2＋、Mg^2＋等盐基离子的增加,进而降低土壤的电导率。腐植酸对番茄的产量和品质也都有显著的影响,能使番茄增产36．5％,并明显提高番茄的VC含量和含糖量。     

Vegetable cultivation under greenhouse conditions leads to rapid accumulation of nutrients,acidification and salinity of soils and groundwater contamination in South-Eastern China

Vegetable cultivation during winter season is economically profitable, but the impact of the intensive production on soil and water quality remains to be studied. The objectives of this study were to investigate the seasonal dynamics of soil nutrients, acidification and salt accumulation in vegetable fields in South-Eastern China. Various vegetables were grown either under open-field conditions or under two different alternating open-field and greenhouse conditions with three replications. Soil samples were collected periodically and analyzed for pH, plant available nitrogen (N), phosphorous (P), potassium (K), electrical conductivity (EC), and urease activity. Water samples from wells located in or near the plots were collected and analyzed for nitrate. Soil nitrate, available phosphate and salt concentrations declined in summer under open-field conditions and significantly increased from December to May under greenhouse conditions. Exchangeable K also decreased in summer season, but did not increase in the spring. Under alternating open-field and greenhouse conditions, nutrient accumulation, soil salinity and acidification were significantly higher for soil used for vegetable cultivation for 2 years (2-y-plot) than that for only half year (0.5-y-plot). The accumulation of nitrate significantly correlated with soil EC and soil acidification. Thirty-two percent of groundwater samples from the 2-y-plot showed a nitrate concentration higher than 50 mg NO₃ l⁻¹. Conversely, no groundwater sample of 0.5-y-plot showed such high nitrate concentration. It can be concluded that the nitrate accumulation in soil used for vegetable cultivation under alternating open-field and greenhouse conditions not only causes soil salinization and soil acidification but also presents a high pollution potential for groundwater.     

The effect of ionic strength on soil P reactions is negligible

The electrolyte concentration of the soil solution affects the availability of some nutrients in the soil, especially of P, but it is not know at what salt concentration the reactions start to be significantly affected and their magnitude. This study was carried out to evaluate the effect of rates of potassium chloride (KCl) on some soil parameters that determine supplying of P, K, Ca, Mg, and Al in an unlimed acid soil. Increasing rates of KCl (from zero up to 2000 mg K kg^–1) were applied to soil samples fertilized with 360 mg P kg^–1. Solution (C_li) and exchangeable (C_si) forms of P, Ca, Mg, K, and Al were determined in the treated soil samples after 30-days of incubation; cation activity in solution and their selectivity coefficients were then calculated. Addition of KCl at rates equal to or above 500 mg K kg^–1 caused a large relative increase on P in the soil solution (P_li) but a small and insignificant increase on the absolute value of P_li. All forms of soil K increased with increases on K applied, and buffer power for K varied according to the range of soil K. At all KCl rates, K displaced Ca, Mg, and Al from the solid phase to the soil solution, but had no effect on the extractable values. The relative preference of cations for the adsorption sites increased with increase on cation valency, and only those selectivity coefficients involving K were affected by K applied.     

Fertilizer inputs, nutrient balance, and soil nutrient-supplying power in intensive, irrigated rice systems. II: Effective soil K-supplying capacity

Based on the analysis of soil K status in 11 long-term fertility experiments in Asia, two approaches for assessing the K-supplying power of lowland paddy soils were evaluated to predict total K uptake by irrigated rice. A regression model combining commonly used static soil test parameters that appeared to integrate measures of K release from nonexchangeable forms as well as chemical factors affecting K activity in soil solution explained 72% of the crop K uptake in NP and NPK treatments. However, this approach would require determination of six soil properties and it does not provide a direct measure of K release dynamics. The second approach used mixed-bed ion exchange resin capsules to measure K release during 2-wk anaerobic incubation. The resin method provided an integrative measure of soil K status and the factors controlling K transformation and diffusion rates, which are embodied in two kinetic parameters describing the dynamics of rapid- and slow-phase K release. The resin method was sensitive to past fertilizer history and the resulting buildup or depletion of soil K reserves and it was a better predictor of total K uptake in the NP and NPK plots (r²=0.82) than static soil tests. The results also indicated that high (Ca+Mg)/K ratios may contribute to K deficiency in rice soils.     

卤水中钾和镁的利用

卤水中含有Na⁺、K⁺、Mg²⁺、Ca²⁺、Li⁺、SO^2-₄和Cl^-等多种离子,其中钾离子、镁离子是生产镁盐和钾盐产品的重要原料,同时合理地利用卤水也可以缓解卤水直接排放带来的环境问题。着眼于卤水资源的利用,重点介绍了以卤水为原料制备各类钾、镁产品的研究进展。通过对比与分析,概括了以卤水为原料制备各类钾、镁产品的技术特点和技术发展趋势,并对卤水资源的利用现状及存在的问题做了简要分析。     

Calcium deficiency identified as an important factor limiting maize growth in acid ultisols of eastern Nigeria

Poor maize growth in unlimed acid soils of eastern Nigeria was investigated with a view to identify the main factors responsible for infertility in such soils. Surface soils collected from 4 sites in the region were amended with (i) CaSO₄ (ii) Ca(OH)₂ and (iii) MgCO₃. Maize was grown in each soil, including an untreated check, in the greenhouse for 4 weeks and tops and roots dry matter were measured.Although CaSO₄ depressed the pH of the soil, it caused a highly significant increase (p = 0.01) in the yield of dry matter of tops and roots and a non-significant increase in the uptake of P and Ca. Exchangeable Al was virtually eliminated when the soil was amended with MgCO₃ but maize growth in this soil was drastically inhibited and symptoms of severe calcium deficiency were observed. Higher yield increases, arising from soil amendment with Ca(OH)₂ relative to CaSO₄ were ascribed to better Ca nutrition rather than reduction in the level of exchangeable Al. Uptake of P and Ca was significantly increased (p = 0.05) by liming with Ca(OH)₂.The results suggest that Ca deficiency is a more serious growth-limiting factor than Al toxicity in the soils tested. The implication of this finding is that much money can be saved by using industrial wastes of relatively low neutralizing value, like cement fluke dust and basic slag, as soil amendments rather than the costly ocnventional liming materials.     

水盐体系相图的计算

提出一种基于Ｌｕ－Ｍａｕｒｅｒ（１９９３）模型的水盐体系相图的计算方法，通过对离子，固相结晶盐的编码处理和一个通用的固液平衡计算模块实现了只需输入水盐体系所含离子名称和体系温度，即可自动进行固液平衡计算，同时得到体系的全息相图的目的，对２７３～５７３Ｋ范围内１０个阳离子和８个阴离子组合的数计十组三离子和四离子水盐体系的固液平衡的计算表明，该计算方法使用十分方便，可应用于两越界 发离和复分解法生产硝     

Phosphorus and potassium soil test and nitrogen leaf analysis as a base for citrus fertilization

A network of six NPK long-term field trials was carried out on different soils of citrus-producing regions of São Paulo state, Brazil, in order to estimate quantitative relations of fruit yield to NPK fertilization and to determine parameters for fertilizer recommendation based on soil testing and leaf analysis. The experiments were set up in an incomplete factorial design 1/2 4³ with 32 treatments, with four yearly rates of N (30, 100, 170 and 240 kg N/ha), P (9, 27, 45 and 63 kg P/ha) and K (25, 91, 157 and 223 kg K/ha). Four to seven harvests were recorded for the six experiments. Response surfaces of the type y = bo + b₁N + b₁₁N² + b₂P + b₂₂P² + b₃K + b₃₃K² + b₁₂NP + b₁₃NK + b₂₃PK were adjusted to the average yields of each trial. Correlation were established for yield increases, expressed as relative yields, and results of soil analysis of P and K, and leaf analysis of N. Soil samples taken at 0-20 cm depth in the beginning of each experiment were analyzed for resin extractable P and exchangeable K using an ion-exchange resin procedure. Yield responses for phosphorus and potassium applications were observed respectively in soils with less than 20 mg dm^-3 of P and 20 mmol_c dm^-3 of K⁺. Yield responses to nitrogen were related to the total content of nitrogen in leaves, being largest for N values of 23 g kg^-1 and smallest for N of 28 kg^-1. With these field information, a practical approach for fertilizer recommendation for citrus, based on soil analysis for P and K and leaf analysis for N, was developed.     

Effect of cation exchange on the distribution and movement of cations in soils with variable charge. II. Effect of lime or phosphate on potassium and magnesium leaching

The effect of Ca(OH)₂ or Ca(H₂PO₄)₂ 2H₂O (MCP) on potassium (K) or magnesium (Mg) leaching through and out of columns of soil with predominantly variable charge was studied. Calcium hydroxide was mixed with soil from the A and B horizon to raise the pH to about 6 or 7, and MCP, equivalent to 952 mg P, was mixed with the A horizon of each soil. Various concentrations of KCl or MgCl₂ were applied as a pulse to the soil surface and leached with five pore volumes of deionised water.Calcium hydroxide or MCP addition increased leaching losses of K and Mg initially present in the soil.Liming to about pH 6 reduced leaching of applied K and Mg in all soils. This was attributed to the increase in the cation exchange capacity (CEC). Applied K leached to a greater extent at pH 7 than at pH 6 in the A horizon of each soil despite a two-fold increase in CEC. However, when Mg was applied to all soils and K applied to soil from B horizons, leaching decreased as the pH increased from 6 to about 7.The addition of MCP increased the CEC of all soils, but this had little effect on the leaching of applied K compared with the untreated soils.A proportion of applied K or Mg was displaced from the soil column for all Ca(OH)₂ or MCP treatments. In many columns, no increase in exchangeable K or Mg in the lower segments of the soil column was found. Where this occurred the activity ratio in the leachate was the same as the equilibrium activity ratio.     

Pot experiments with Italian ryegrass: Yields and evaluation of soil potassium status with different methods of applying potassium fertilizer

Italian ryegrass (Lolium multiflorum) is studied in pot experiments on a soil of low potassium status. Different methods of applying potassium are compared which result in different dry-matter yields in successive cuts; the effect of the different K applications are also compared on the decreasing or improving evolution of the K soil status during and after the cropping. The compensation with amounts of K corresponding to the K uptake of the previous cut is particularly interesting in terms of fertilizer efficiency.