Soil and Plant Testing for Iron: An Appraisal

Iron (Fe) deficiency chlorosis in crops is common in high-pH calcareous soils. Soil and plant testing is routinely used for diagnosing iron (Fe) deficiency chlorosis in crops, with mixed results. This article presents an overview of the factors that influence soil and plant tissue testing results. It is clear that soil tests for Fe are dominantly influenced by soil pH, bicarbonate, and moisture regime rather soil test result per se. This is because the solubility of Fe is more regulated by soil pH and moisture regime. Plant tissue testing for Fe can complement the results of soil testing for Fe. But at times, especially in calcareous soils, total Fe in plant tissue is not related to Fe deficiency, but metabolically active Fe is better at diagnosing the occurrence of the disorder. A combined use of soil and plant tissue testing seems more helpful in diagnosing Fe deficiency chlorosis disorder in crops.     

Soil Testing and Plant Analysis Relationships for Irrigated Chile Production

In a field study of irrigated chile (Capsicum annum L.) production in southeastern Arizona and southwestern New Mexico from 2008 through 2009, soil and tissue test samples were analyzed for a spectrum of plant nutrients at 16 different sites, including nitrogen (N), phosphorus (P), potassium (K), zinc (Zn), iron (Fe), and boron (B). The objectives were to evaluate soil and tissue nutrient testing procedures and to establish basic soil and plant tissue-testing guidelines and recommendations with respect to yield potentials. Soil samples were collected before planting. Plant tissue samples from plots at all sites were collected at the following four stages of growth: first bloom (FB), early bloom (EB), peak bloom (PB), and physiological maturity (PM). Fertilizer and nutrient inputs were monitored, managed, and recorded within current extension guidelines for irrigated chiles. Results for soil and tissue analyses were compared to yield results. The results provide estimates for baselines, which can be tested through subsequent calibration experiments to establish recommendations for critical soil- and tissue-test values. Absolute minimum soil-test nutrient values were identified as 10 parts per million (ppm) P, 110 ppm K, 0.3 ppm Zn, 2.0 ppm Fe, and 0.25 ppm B. Absolute minimum FB leaf tissue test values were 0.2% P, 4.5% K, 10 ppm Zn, 80 ppm Fe, and 30 ppm B. Complete data sets for leaf and petiole tissue-test values for all stages of growth were collected. These soil-test and plant nutrient values will be evaluated in subsequent experiments to better define fertilizer nutrient inputs and to gain better nutrient-management efficiencies in irrigated chile production systems.     

一株固氮解磷菌的筛选鉴定及其对花生的促生作用研究

本研究从南京板桥镇的灰潮土中,筛选出了一株高效固氮解磷菌,命名为JX14,其固氮酶活性达C2H438.9 nmol/(h·ml),对磷酸三钙的转化量达96.19 mg/L。通过形态观察、生理生化特征及16S r DNA基因序列分析,确定JX14为贪噬菌属(Variovorax sp.)。在温室条件下进行花生盆栽试验,结果表明,接种JX14菌株的处理,土壤NH4+-N、NO3–-N、矿质氮含量较不接菌处理分别提高了1.08、1.18、1.16倍,土壤有效磷含量提高了18.14%。花生根系总长、表面积、体积以及根尖数,较对照分别提高了1.61、1.28、1.37、1.12倍,花生根系变得更长更粗并且具有更多的分支,增强了根对土壤中营养元素的吸收,花生地上部鲜重、株高显著提高了44.78%、14.10%,花生全氮磷钾含量分别显著提高了35.14%、171.43%、133.33%。该结果为植物促生菌JX14在农业生产上的应用提供了理论依据和研究基础。     

测土配方施肥研究的文献计量分析

测土配方施肥是推进新农村建设的一项重要举措。运用文献计量学方法,以中国基础知识设施工程文献数据库中的4数据库和美国科学信息研究所的Web of Science数据库中的6数据库为数据源,分别从论文发表时间、刊登期刊、被引频次、学科及研究方向、研究人员及研究单位、资金支持、研究物种和研究区域等方面对中外截止至2016年6月以来发表的测土配方施肥研究文献进行计量统计。结果表明,国内相关文献发表数量与政策实施保持了高度一致性,2005年文献数量开始激增,2010年之后论文数量保持较平稳波动;农林科研院校和地方土壤肥料工作站是国内测土配方施肥研究的中坚力量;目前测土配方施肥技术主要应用在水稻、玉米、小麦和马铃薯4大粮食作物上,研究区域主要集中在我国东部地区的省份和13大粮食主产区,西部研究较少;测土配方施肥的研究未来方向是往计算机软件及计算机应用、林业等学科专业方向倾斜。     

Adopting a Robotic pH Instrument for Soil and Soil-Buffer pH Measurements in a Soil Test Laboratory

Optimum software settings were evaluated to minimize time of analysis without sacrificing data quality on an AS-3010D LabFit robotic instrument. There was little to no difference between soil and soil-buffer pH values measured via manual methods and LabFit analysis with four software settings. A setting for routine laboratory analysis was determined by evaluating r² values from a comparison of LabFit versus manual measurements. Settings for routine analysis were adopted as follows: 5 s for sample delay time, 60 s for maximum sample time, 10 readings for stability, 0.02 for pH stability, 0 s for buffer run delay, and probe rinsing after every 40 samples. These settings were evaluated on 2933 Kentucky soil samples where robotic versus routine analysis of soil and soil-buffer pH resulted in r² values of 0.94 and 0.82 for soil pH and soil-buffer pH, respectively. The results validated the utility of robotic instruments for soil pH analysis.     

土壤因子对植物缺铁失绿的影响

本文主要从土壤 pH ,重碳酸盐 ,和氮素形态等几方面综述了各种土壤因子对土壤缺铁失绿的影响 ,并提出了进一步加强研究的方向     

Soil Fertility Amendments and White Grub Populations of Turf

Liming materials, calcium carbonate versus calcium magnesium silicate, were compared for effects on native white grub (Coleoptera: Scarabaeidae) populations in a New Jersey lawn. A silt loam soil near Princeton, N.J., of mixed cool-season turf with an initial pH of 5.0 received applications of either liming material in January 2007 for a target pH of 6.5. Control plots received no lime application. Grub numbers were reduced by more than 50% in plots amended with either calcium magnesium silicate or calcium carbonate when compared with the controls. Both calcium magnesium silicate and calcium carbonate were similarly effective in achieving this benefit.     

长期不同供磷水平驯化的土壤微生物的遗留效应--基于对植物生长、养分吸收、土壤酶活性及菌根特征的分析

在集约化农田生态系统中,长期过量施用磷肥导致土壤中磷的累积,是否存在累积磷驯化（training）微生物的遗留效应。本研究依托长期定位玉米试验地（始于2007）,以长期不同供磷水平（来源于施用P2O5 0、75、300 kg·hm-2的处理,分别为P0、P75、P300）石灰性土壤中的微生物为研究对象,通过盆栽接种微生物,探究不同磷供应驯化下的土壤微生物,在两个基质供磷水平（不施磷No P 和+P 30 mg·kg-1）下对玉米和三叶草植物生长、养分吸收、土壤酶活性及菌根特征的影响。结果表明,菌剂类型（灭菌处理,原位菌剂）显著影响玉米和三叶草地上部生物量和磷吸收量。在两个基质磷水平处理,相比于灭菌菌剂处理,接种原位菌剂显著提高了三叶草地上部生物量和磷吸收量,但三种菌剂之间差异不显著。 在No P条件下,相比于灭菌处理,接种原位菌剂对玉米地上部生物量无显著影响。在+P条件下,接种原位菌剂显著降低了玉米的生物量;在两个基质供磷水平下,玉米地上部生物量在P300处理中显著高于P0和P75。菌剂和基质供磷水平共同影响土壤酶活性。与P0和P75相比,P300菌剂显著降低了三叶草土壤中过氧化物酶活性,提高了No P条件下玉米土壤中过氧化物酶和几丁质酶的活性。在No P条件下,接种P75显著提高了玉米土壤中酸性和碱性磷酸酶的活性。两种作物的菌根特征不同,接种位P300三叶草根系丛枝菌根真菌的侵染率显著低于P0和P75,而玉米根系的侵染率在三种菌剂之间差异不显著。综上,基质供磷水平以及植物种类共同影响累积磷驯化土壤微生物的效应,说明磷肥管理需要考虑植物-微生物的特性。     

Development of a New Soil Extractant for Simultaneous Phosphorus,Ammonium, and Nitrate Analysis

Abstract

A new soil extractant (H³A) with the ability to extract NH₄, NO₃, and P from soil was developed and tested against 32 soils, which varied greatly in clay content, organic carbon (C), and soil pH. The extractant (H³A) eliminates the need for separate phosphorus (P) extractants for acid and calcareous soils and maintains the extract pH, on average, within one unit of the soil pH. The extractant is composed of organic root exudates, lithium citrate, and two synthetic chelators (DTPA, EDTA). The new soil extractant was tested against Mehlich 3, Olsen, and water for extractable P, and 1 M KCl and water‐extractable NH₄ and NO₂/NO₃. The pH of the extractant after adding soil, shaking, and filtration was measured for each soil sample (5 extractants×2 reps×32 soils=320 samples) and was shown to be highly influential on extractable P but has no effect on extractable NH₄ or NO₂/NO₃. H³A was highly correlated with soil‐extractable inorganic N (NH₄, NO₂/NO₃) from both water (r=0.98) and 1 M KCl (r=0.97), as well as being significantly correlated with water (r=0.71), Mehlich 3 (r=0.83), and Olsen (r=0.84) for extractable P.     

中国农田土壤重金属污染与其植物修复研究

通过对我国部分城市农田土壤及农作物重金属污染状况的调查,分析了我国农田土壤重金属污染的特点以及污染的来源,最后介绍了重金属污染土壤的植物修复技术以及该技术的优点和局限性.     

土壤酸碱性质对尿素转化特征的影响

试验研究了3种酸性土壤和3种碱性土壤施入尿素后,对土壤pH值变化、氨挥发特性、氮素转化及A l元素活性的影响。试验结果表明:土壤酸碱性对尿素水解的影响与尿素浓度有关,在常温25℃下,3种酸性土壤的pH值在短期内都随着加入尿素浓度的增大而急剧上升,而3种碱性土壤的pH值却是随着加入尿素浓度的增加先增加再减少然后又增加,且其变化的幅度较之酸性土壤小;动态试验表明,pH值上升的现象是短期的,6种土壤pH值达到最大值后缓慢下降,2周后3种碱性土壤的pH降到比原来更低的程度。氨挥发强度与土壤pH变化同步;在酸性土壤和碱性土壤中,氨气日挥发量都是先从小到大出现峰值,然后又降低;酸性土壤氨挥发高峰期约在7~9天,碱性土壤的氨挥发高峰期约在第3天左右。各处理NH4+-N含量和NO3--N含量与土壤pH变化趋势相似,在前2~4星期增加到峰值,而后开始下降并保持不变。短期内,交换性A l随着尿素浓度的增大而急剧下降,交换性A l含量与土壤pH变化呈显著负相关,施用尿素短期内能显著降低酸性土壤交换性铝的含量。     

淹水还原作用对红壤镉生物有效性的影响

用添加20 mg.kg^-1镉（Cd）的红壤（pH 4.46）室温淹水培养41 d,研究淹水还原作用对Cd溶解性的影响,同时设置水稻培养试验,在红壤淹水初期（1-11 d）和后期（淹水31-41 d）植入水稻秧苗,以比较不同淹水时段红壤Cd对水稻的有效性。结果表明,红壤淹水后1-25 d水溶性Cd浓度由0.210 mg.L^-1上升到0.254 mg.L^-1,淹水28-40 d水溶性Cd浓度由0.221 mg.L^-1下降到0.092mg.L^-1,在淹水1-11 d和31-41 d水稻茎叶Cd含量分别为48.37和16.25 mg.kg^-1。说明淹水初期红壤Cd活性和生物有效性高于淹水后期。通过红壤淹水过程Fe、Cd溶解性及CEC、阳离子饱和度等的研究,表明红壤淹水后氧化铁的还原溶解作用导致pe＋pH下降和pH上升,由此控制着Cd活性和生物有效性的升降。     

Influence of Liming on Soil Chemical Properties and Plant Growth of Pineapple (Ananas Comusus L.Merr.) On Red Acid Soil,Lampung, Indonesia

ABSTRACT

Red acid soil is generally distributed in humid tropical areas under high rainfall. The main constraint is usually the extremely low pH of the soil due to the very intensive leaching of the bases from the soil. At the same time, however, the soluble micro elements, such as iron, are high. This can cause plant toxicity. The liming of acidic soils is normally performed to reduce the iron toxicity as the first step toward providing a balanced nutrition for cultivated plants. The objective of this study is to determine the effects of liming on the soil pH, on the decrease of iron in the soil and on the growth of the pineapple. The research was done in the Greenhouse of the Research and Development Department, PT Great Giant Pineapple, Lampung, Indonesia, from November 2015 to April 2016. The design of the experiment was arranged as a completely randomized design with seven treatments and three replications, consisting of: No dolomite (D0), dolomite 1 t ha^?1 (D1), dolomite 2 t ha^?1 (D2), dolomite 3 t ha^?1 (D3), dolomite 4 t ha^?1 (D4), dolomite 5 t ha^?1 (D5) with added Fe-EDTA and for the control treatment, no dolomite and no Fe-EDTA (C0). The results showed that an increase in the dolomite dose can increase the pH, potassium (K), calcium (Ca) and magnesium (Mg) in the soil and can decrease the iron (Fe) in the soil significantly. Increasing the pH, K, Ca and Mg and decreasing the Fe in the soil were seen to influence the growth of the pineapple. In particular, the leaf area of the pineapple plant increased considerably. The other parameters also increased, but not significantly.     

Leaf Tissue Testing and Soil and Plant Tissue Relationships for Nitrogen Management in Carrots

Abstract

Nitrogen (N) management in carrot (Daucus carota L. var sativus) production systems is critical for increasing efficiency of crop production, decreasing costs, and decreasing nitrate leaching losses to groundwater. Leaf tissue testing may be an appropriate method to monitor and meet carrot N requirements. A field trial was conducted in three locations to 1) determine if “critical tissues” identified in previous research are appropriate for leaf tissue testing in N management of carrots, 2) determine the effects of various N regimes on soil and tissue N concentrations, 3) describe the relationships among soil N concentrations, tissue N concentrations, and yield for several N regimes, and 4) study the effects of N regimes on growth, yield, and recovery of marketable grades of carrots. Nitrogen critical tissues for leaf tissue testing were not useful in N management. Overall, results showed no significant differences in soil and tissue N levels due to increasing N regimes. Correlations among soil, tissue, and yield differed at each harvest but most were not significant. N concentration was higher in soils at a depth of 0–15 cm compared to 15–30 cm. Total N concentrations in tissues decreased over sequential harvests. No clear relationships emerged comparing tissue NO₃‐N to soil N measurements over the entire growing season. There were no significant differences in growth and yield of carrots in response to N regimes. Interestingly, a N rate of 0 kg/ha had significantly more fancy‐grade carrots than a N rate of 200 kg/ha. There were no significant differences in culls due to increasing N application.     

碱性水田土壤施用硅肥的效应

选取碱性水田土壤,采用盆栽试验的方法,研究了施用硅肥后水稻生育期土壤溶液pH、Eh、硅浓度及对水稻产量的影响。结果表明,各处理pH经历了一个迅速降低,趋于中性的过程。单施硅肥对pH影响不大;施用葡萄糖或葡萄糖与高炉渣配施可明显降低水稻生育前期土壤溶液pH。各处理Eh的变化基本呈现为近似“W”形。淹水初期,施肥各处理土壤Eh均低于对照;后期施硅处理的Eh高于对照,而单施葡萄糖和高炉渣与葡萄糖配施处理Eh低于对照。各处理土壤溶液硅的浓度都经历了一个先上升达到高峰,然后逐渐下降,最终趋于稳定的过程。与对照相比,施用硅肥可不同程度地提高水稻生育期土壤溶液硅的浓度和不同生育期水稻植株含硅量;施用葡萄糖可提高水稻营养生长期土壤溶液中硅的浓度,但对提高水稻植株硅含量的作用不大;施用硅肥可以显著提高水稻产量,施用葡萄糖没有增产作用。     

Phosphorus Amendment of a Lead-Spiked Soil with Low Phosphorus Availability: Roles of Phosphorus on Soil and Plant Lead

Phosphorus (P) is both a macronutrient for plants and an effective amendment to reduce lead (Pb) toxicity in soil. Thus, in Pb-polluted soil with low P availability, P will act as a nutrient as well as a Pb-immobilizing agent. However, this has not been fully investigated. A soil with 2.50 mg kg^?1 Olsen P was spiked with soluble Pb and then amended with superphosphate to examine the effect of P on soil Pb availability and ryegrass (Lolium perenne L. cv. Aubisque) growth. It was found that P/Pb = 2 increased ryegrass yield by 804% and decreased root Pb concentration and soil diethylenetriaminepentaacetic acid (DTPA)–extractable Pb concentration by 25.6% and 1.0%, respectively. As P amendment increased to P/Pb = 4, both plant yield and root Pb concentration declined compared with P/Pb = 2. Results of the sequential extraction indicated that the proportion of carbonate phase Pb decreased, while that of the manganese oxide phase increased as P was added. The proportion of residual Pb was little affected by the amendment. The results suggest that in soils with low P availability and high Pb availability, availability of soil Pb and root concentration of Pb are less affected, whereas the toxicity of Pb is greatly depressed by the P amendment; P/Pb = 2 is high enough to alleviate the stresses of low P availability.