Sugarcane Biomass Yield Response to Phosphorus Fertilizer on Four Mineral Soils as Related to Extractable Soil Phosphorus

ABSTRACT

The efficient use of phosphorus (P) fertilizers is very important in South Florida so that the environmental impact is minimal while meeting crop demand. To ensure that this is accomplished, an updated soil test P calibration is needed for sugarcane (Saccharum spp.) grown on Florida mineral soils, which accounts for almost 30% of the total sugarcane planted in the state. An outdoor pot experiment was conducted with the objective of evaluating four soil extractants for potential use in soil test P calibrations. Sugarcane cultivar CL 88–4730 was grown in 26L pots in a randomized complete block design with four replications of four P fertilizer rates (0, 38, 76, and 152 mg P L^?1 soil) and four soil series (2 Spodosols, 1 Entisol, and 1 Alfisol). Sugarcane biomass was significantly increased with P fertilizer application and extractable soil P significantly increased with increasing P fertilizer rate. Strongest relationships of extractable soil P with relative fresh weight yield were determined with the water, acetic acid, and ammonium acetate extractants. All extractants tested, including Mehlich 3, had significant relationships with relative yield and leaf P concentration and so all these extractants should be considered in further field calibration studies with sugarcane on Florida mineral soils.

Abbreviations: EAA: Everglades Agricultural Area; EREC: Everglades Research and Education Center; OM: organic matter; TSP: Triple superphosphate     

Calibration and Categorization of Plant Available Silicon in Rice Soils of South India

ABSTRACT

Calibration of field crop responses to nutrient availability acts as a basis for making fertilizer recommendations from soil and tissue analysis. The purpose of this study was to evaluate and summarize silicon (Si) fertilization of rice in different soils of south India. The experiment consists of four levels of calcium silicate as Si with three replications. Initially, soils were analyzed using eleven different extractants. The grain and straw yield were recorded and analyzed for Si content. The critical levels for plant available Si in the soil ranged from 14 mg kg^?1 (distilled water-1) to 207 mg kg^?1 [0.005 M sulfuric acid (H₂SO₄)]. There was a wide variation in low, medium, and high categories of plant available Si for different extractants calculated based on percent relative yield. The critical level of Si in straw and grain were 2.9 and 1.2%, respectively.     

Divergent Relationships of Phosphorus Soil Tests in Temperate Grassland Soils

Abstract

Various soil tests are used to estimate phosphorus (P) availability for both crop uptake and potential loss to water. Conversion equations may provide a basis for comparison between different tests and regions, although the extent to which information can be interchanged is uncertain. The objective was to determine and quantify relationships between specific soil test extractants for samples taken annually in October and February over 4 years from four sites in each of eight soil series under grassland. The extractants comprised Mehlich‐3, Morgan, Olsen, Bray‐1, lactate–acetate, CaCl₂ (1∶2 and 1∶10 soil–solution ratios), and resin. The results showed distinct relationships for each soil series, for which individual lines regression models (different intercepts and slopes) were superior to a single conversion equation across all soils. The ensuing difference between soils was large and ranged from 1.9 to 8.0 and 9.2 to 15.6 mg kg^?1 P for Morgan and Olsen, respectively, at 20 mg kg^?1 Mehlich‐3 P. Generally, the environmentally oriented tests CaCl₂ and resin correlated best with Morgan. Some soil‐specific limitations were also observed. CaCl₂ was less efficient than Morgan, and Morgan less efficient than Mehlich‐3 on a high Fe–P soil derived from Ordovician‐shale diamicton, compared with the general trend for other soils. This finding suggests that further disparity may arise where evaluation of critical, or other, limits across regions involves even a limited sequence of tests.     

土壤硅磷元素交互作用研究进展

介绍并讨论了国内外有关土壤硅、磷两种元素交互作用的研究动态与进展。硅、磷元素在植物体内的交互作用并非由于硅在生理上代替了植物对磷的需要,而是由于硅的存在降低了过量铁、锰、铝等金属离子的毒害,从而改善了植物的磷素营养。硅、磷元素可以相互促进肥效,提高各自的生物利用率。二者在土壤中存在着竞争性吸附关系,其中土壤对磷的吸附结合能更大。磷的施用不仅降低了土壤对硅的吸附,而且增加了硅的解吸。     

酸化与富磷对农田土壤硅有效性的影响

目前，大量农田土壤及其生态功能正经受着土壤酸化的严重威胁，而土壤pH深刻影响着土壤中硅、磷养分的移动性及两者间的相互作用。关于硅肥施用可有效提升土壤磷素植物有效性的研究已有大量报导，但在农业集约化生产区，土壤磷素已大量累积的背景下，磷富集对土壤硅移动性与有效性的影响及其机制尚不清楚。选取2种不同有效硅水平的农田土壤（低有效硅土壤LASi：有效硅28.20 mg?kg-1；高有效硅土壤HASi：有效硅253.6 mg?kg-1），通过等摩尔浓度硅磷竞争吸附试验、土壤培养试验等，探究人工酸化与磷添加对土壤硅吸附性能与移动性的影响及其机制。结果表明，酸化土壤pH在3.5~8.0范围内，当硅与磷等摩尔浓度同时添加时，磷的存在会降低硅的吸附，各相应pH的LASi与HASi 2种土壤对硅的吸附量分别降低26%~74%、31%~84%。这说明，土壤对磷的吸附大于对硅的吸附。设置土壤pH3.5~8.0范围内，降低pH可降低土壤对硅的吸附；磷添加降低土壤硅吸附的效应，在高pH条件下更为显著。土壤酸化与磷添加降低了土壤对硅的吸附，降低了土壤有效硅（HOAc-NaOAc-Si）水平；不同类型土壤移动性硅（CaCl2-Si）水平对酸化与磷添加的响应不同，具体机理尚需进一步研究。     

酸性和中性水田土壤施用硅肥的效应研究 Ⅱ.对水稻吸收硅素及产量的影响

分别选取酸性和中性水田土壤进行盆栽试验,研究施用硅肥对水稻不同生育期硅素吸收状况及产量的影响,以期揭示施用硅肥提高不同类型土壤供硅能力、改善植株硅素营养及增加产量的作用机制。结果表明,从拔节期到抽穗期水稻植株体内硅的含量有较大幅度的降低,而后又逐渐升高。施用硅肥可明显提高水稻植株体内硅的含量,尤以高炉渣与葡萄糖配合施用和单施高炉渣两个处理效果最好,极显著高于对照及其他处理。在酸性水田土壤上施用硅肥的增产效果较为明显,高炉渣与葡萄糖配施处理的增产率高达16.99%,且成熟期水稻植株含硅量与稻谷产量间存在显著的直线正相关关系;在中性水田土壤上施硅则无显著增产效果。总之,高炉渣与葡萄糖配合施用能更有效地改善土壤的供硅能力,进而提高水稻产量,其在酸性水田土壤上的施用效果尤为显著。     

添加硅、硼元素对甘蔗组培苗生长的影响

以“新台糖１６号”甘蔗品种试管苗为材料,采用液体培养方法,以ＭＳ为基本培养基,附加激素ＢＡ ３ｍｇ／Ｌ、ＮＡＡ０．５ｍｇ／Ｌ,ＮａＳｉＯ３２００ｍｇ／Ｌ,苗增殖率比对照提高６８％,叶色浓绿、叶片挺直、硬、不早衰。比对照延长生长期２３ｄ。生根阶段,以ＭＳ为基本培养基,附加ＮＡＡ１ｍｇ／Ｌ、硼酸３０ｍｇ／Ｌ,生根数比对照增加５３％,根长、苗壮。     

水稻土硅素肥力的研究现状与展望

本文综述了水稻土硅素肥力的研究现状 ,主要内容包括土壤中硅的形态 ,影响水稻土供硅能力的因素 ,判断水稻土供硅能力的方法及标准及改善水稻土供硅能力的技术措施 ,同时指出了水稻土硅素肥力今后研究的重点 .     

Comparison of Mehlich-3 and Ammonium Bicarbonate-DTPA for the Extraction of Phosphorus and Potassium in Calcareous Soils from Florida

Developing a fast and reliable soil testing method is critical for improving soil testing efficiency and ensuring reliable fertilizer recommendation. The objectives of this study were to evaluate Mehlich-3 (M-3) as a replacement for ammonium bicarbonate-diethylenetriaminepentaacetic acid (AB-DTPA) to extract phosphorus (P) and potassium (K) and to determinate the relationships between extractable P and K and their uptakes by crop in calcareous soils. M-3 and AB-DTPA were compared by using two approaches. In the first approach, the amounts of extracted P and K were compared by analyzing soil samples collected from agricultural production areas; in the second approach, snap beans (Phaseolus vulgaris) were grown in pot to determine the P and K uptakes by crop. There were significant correlations between M-3 and AB-DTPA for both soil test P and K based on soils collected from the agricultural field and the pot study. Soil test P and K by both extractants were significantly correlated with their uptakes by snap bean. The critical value of M-3-P regarding snap bean uptake was 47 mg kg^?1 and was higher than that (18 mg kg^?1) for AB-DTPA-P, whereas critical soil test K levels were similar between M-3 and AB-DTPA. M-3 was identified as an alternate improved extraction method instead of AB-DTPA in calcareous soils based on this study. However, more work will be needed to identify the correlation of the two extractants and crop responses under a field condition.     

Evaluation of Mehlich 3 as a Universal Nutrient Extractant for Australian Sugarcane Soils

This study evaluated the suitability of the Mehlic h3 universal extractant as a part of a multielement test to assess the nutrient status of Australian sugarcane soils. Soil samples from BSES Soil Exchange Programs, representing all major soil types and geographic sugarcane-growing regions, were analyzed using existing BSES, acid-based extraction methods for calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), copper (Cu), zinc (Zn), iron (Fe), manganese (Mn), and phosphorus (P) and the ASPAC 10B3 method for sulfur (S). These were compared with the Mehlich 3 procedure. Mehlich 3 results for Ca, Mg, Na, S, and Mn correlated highly with the BSES procedures (R² = 0.95, 0.98, 0.99, 0.91, and 0.91, respectively). Satisfactory correlations were also obtained with 0.1 M HCl–extracted Zn, Cu, and Fe (R² = 0.89, 0.85, and 0.85, respectively) and with the BSES sulfuric acid (H₂SO₄)–extracted P (R² = 0.81). The poorest correlation (R² = 0.79) was observed for K. In conclusion, the Mehlich 3 procedure is suitable as a diagnostic tool to assess the basic nutrient status of Australian sugarcane soils.     

水稻土中硅磷元素的存在形态及其相互影响研究

采用室内培养试验研究不同施硅和施磷处理对水稻土中硅、磷不同存在形态的影响。结果表明 ,硅磷具有相互促进肥效的关系。施硅影响土壤无机磷的形态 ,硅的施用增加了土壤中Ca2 -P、Al-P和O -P的含量 ,Ca8-P、Ca10 -P变化不明显 ,Fe -P的含量显著降低。其中原因可能是Fe -P在水稻土中活性较高。硅酸钠与硅酸钙相比 ,前者的作用更为明显。施磷影响土壤硅的不同形态 ,磷的施用增加了土壤中水溶性硅和活性硅的含量 ,降低了无定形硅的含量 ,这可能与磷的存在改变了土壤 pH有关     

Plant Availability of Cadmium in Soils: I. Extractable Cadmium in Newly and Long-Term Cultivated Soils

Abstract

Effects of long-term use of phosphate fertilizers on extractable soil Cd in relation to its concentrations in plants were investigated. “Paired” soil samples were collected from newly and long-term cultivated fields and analyzed for Cd by extraction with NH₄OAc, DTPA, NH₄OAc-EDTA, NH₄NO₃, HCl and CaCl₂. Plant samples were also collected and analyzed for Cd. Significant differences in extractable Cd by all the extractants except NH₄NO₃ were observed between the newly and long-term cultivated soils. The Cd concentrations in plants were not increased by the elevated extractable Cd. Although significant relationships were observed between plant Cd and extractable soil Cd, none of the extractants used alone gave a good assessment of plant-available Cd for all the samples used in this study.     

Solubility Relationships of Iron and Evaluation of its Fertility Status in Degraded Soils

This study was conducted to determine the solubility of iron (Fe) and identify the solid phases responsible for controlling its solubility in these soils by using Baker soil test (BST) computer program. The results indicated that the ferric ion (Fe³⁺) activity in all the soils, except the acidic ones, nearly approached the theoretical solubility line of known minerals, namely soil-Fe, amorphous-Fe, maghemite, and lepidocrocite. Solubility of Fe in acid soils of Ranchi (soil 3) and Cooch-Behar (soil 6) did not match the theoretical solubility lines of any of the known minerals. The acidic soils of Ranchi and Cooch-Behar were sufficient for Fe with respect to both quantity and intensity factor based on BST rating, while alkaline (soil 1) and calcareous (soil 5) were sufficient in reserve Fe; deficiency of iron still could be suspected because of high pH. These findings elucidate the role of solid phase controlling iron solubility in soil solution of degraded soils.     

Relationship between Olsen P and Ammonium Lactate–Extractable P in Portuguese Acid Soils

The soil phosphorus (P) test in Portugal is based on extraction with ammonium lactate (AL) at acidic pH. Because this test is rarely used in other countries, it is desirable to see whether the AL-P values correlate with the more commonly used P tests. In this work, we compared AL-P with bicarbonate-extractable P (Olsen's method) for a group of 48 samples from Portuguese acidic soils differing widely in P status. Despite their contrasting composition, both reagents extracted phosphate from the same sources, albeit in different proportions. Both Olsen P and AL-P were strongly correlated with resin-extractable and dilute electrolyte-desorbable P, which are respectively related to the soil contents in phytoavailable P and P that can be released to runoff or drainage water. Olsen P and AL-P were strongly correlated (R² = 0.870), the correlation became stronger when three overfertilized soils were excluded (Olsen P = 2.35 + 0.45 AL-P; R² = 0.908; P ≤ 0.001, n = 45). No correlation was observed for a group of soils recently fertilized with Gafsa phosphate probably because the acidic AL reagent dissolved residual calcium phosphate, thus overestimating the soil content in desorbable P. On the basis of the present results and the AL-P-based fertility classes used for fertilizer recommendation purposes, Olsen P–based fertility classes were tentatively proposed for Portuguese acidic soils.     

Relationship Between Extractable Metals in Acid Soils and Metals Taken Up by Tea Plants

Abstract

The accumulation of heavy metals in plants is related to concentrations andchemical fractions of the metals in soils. Understanding chemical fractions and availabilities of the metals in soils is necessary for management of the soils. In this study, the concentrations of copper (Cu), cadmium (Cd), lead (Pb), and zinc (Zn) in tea leaves were compared with the total and extractable contents of these heavy metals in 32 surface soil samples collected from different tea plantations in Zhejiang province, China. The five chemical fractions (exchangeable, carbonate‐bound, organic matter‐bound, oxides‐bound, and residual forms) of the metals in the soils were characterized. Five different extraction methods were also used to extract soil labile metals. Total heavy metal contents of the soils ranged from 17.0 to 84.0 mgCukg^?1, 0.03 to 1.09 mg Cd kg^?1, 3.43 to 31.2 mg Pb kg^?1, and 31.0 to 132.0 mg Zn kg^?1. The concentrations of exchangeable and carbonate‐bound fractions of the metals depended mainly on the pH, and those of organic matter‐bound, oxides‐bound, and residual forms of the metals were clearly controlled by their total concentrations in the soils. Extractable fractions may be preferable to total metal content as a predictor of bioconcentrations of the metals in both old and mature tea leaves. The metals in the tea leaves appeared to be mostly from the exchangeable fractions. The amount of available metals extracted by 0.01 mol L^?1 CaCl₂, NH₄OAc, and DTPA‐TEA is appropriate extractants for the prediction of metals uptake into tea plants. The results indicate that long‐term plantation of tea can cause sol acidification and elevated concentrations of bioavailable heavy metals in the soil and, hence, aggravate the risk of heavy metals to tea plants.     

硅肥对冬小麦磷素吸收转运的影响

研究了大田条件下硅对小麦(Triticum aestivum L.济麦22)干物质积累与分配比例,磷吸收转运的影响。结果表明:施用硅酸钾肥料促进作物对P的吸收与利用,从而促进小麦生长和提高生物量;在适宜的硅酸钾肥料施用量90 kg hm^-2下,小麦地上部干物质积累及分配表现出最优,不适宜的硅酸钾肥料施用量将不利于穗形成期干物质在穗部的优先分配;小麦总硅吸收量与总磷吸收量呈显著线性相关;穗中13.8%～28.3%的磷素是靠秸秆转运而来,施硅肥显著促进了磷素在穗的累积,且累积量随着施硅肥增加而降低,各施硅肥处理的磷素转运效率在36.6%～44.3%之间,随着施硅肥量增加而降低。本研究表明,在土壤酸化严重的胶东地区,推荐T2处理(90 kg硅酸钾hm^-2),能取得较好的小麦增产效果。     

Extractable Micronutrients Status of Soils in a Plinthitic Landscape at Zaria,Nigeria

Desilication and leaching are processes that accompany plinthilization, leading to nutrient depletion. Soils from 12 profiles in a plinthitic landscape were analyzed for extractable micronutrients [iron (Fe), zinc (Zn), manganese (Mn), and copper (Cu)]. Soils of the landscape from crestal to lower‐slope position contain plinthite in the profile, whereas those of the valley floor are devoid of plinthite. The micronutrients were extracted using diethylenetriaminepentaacetic acid (DTPA) and 0.1 M hydrochloric acid (HCl). The results showed that 0.1 M HCl extracted more of the micronutrients than DTPA. The DTPA‐extractable Fe, Zn, Mn, and Cu in all the soils ranged from 1.15 to 12.44 (mean, 3.69); 0.71 to 2.75 (mean, 1.86); trace 12.44 (mean, 3.35), and trace 3.76 (mean, 0.63) mg kg^?1, respectively. The DTPA‐extractable micronutrient contents were generally greater than the critical available level (4.5 mg kg^?1 for Fe, 0.8 mg kg^?1 for Zn, 1.0 mg kg^?1 for Mn, and 0.2 mg kg^?1 for Cu). The 0.1 M HCl‐extractable micronutrients in the landscape ranged from 8.00 to 30.40 (mean, 15.19); 0.30 to 6.49 (mean, 1.35); 1.00 to 27.20 (mean, 7.74); and 0.26 to 15.0 (mean, 2.77) mg kg^?1 for Fe, Zn, Mn, and Cu, respectively. Both DTPA‐ and 0.1 M HCl‐extractable micronutrients were generally lower in the plinthitic horizons than in the nonplinthitic horizons and higher in the Ap than the subsoil horizons. Correlation analysis showed a significant relationship between DTPA‐Fe and DTPA‐Mn, Cu, and organic carbon (r = 0.913**, 0.411**, and 0.385**). There was a significant and positive relationship between 0.1 M HCl‐extractable Mn and organic carbon (C), total nitrogen (N), and available phosphorus (P) (r = 0.413**, 0.337**, and 0.350**, respectively).     

Soils and 'managed retreat' in South East England

Abstract. Much of the low-lying farmland around the coastline of south-east England was once inter-tidal salt marsh, which was subsequently reclaimed from the sea and converted to farmland. It is becoming increasingly uneconomic to maintain the embankments which protect this land from the sea. 'Managed retreat' involves relocating the embankments further inland and recreating inter-tidal habitat in front of them. Salt marsh not only provides a protective buffer for these sea walls by dissipating wave energy, but is also important as a habitat for birds and as a source of organic matter for fish and inter-tidal fauna. When 'managed retreat' takes place, the creation of inter-tidal habitat occurs on soils that have undergone physical and chemical changes, some of which are irreversible. However, the indications are that rapid sedimentation creates conditions in which salt marsh plants germinate and become established; soil salinity rises quickly to a level which restricts competition from terrestrial plants, and deposited sediment is relatively rich in available phosphorus. The physical properties of the old agricultural soil influence the subsequent development of creeks.     

Spectrophotometric and Inductively Coupled Plasma–Optical Emission Spectroscopy Determination of Gallium in Natural Soils and Soils Polluted by Industry: Relationships between Elements

The aim of this work was to determine gallium contents in different soils of Poland using a sensitive spectrophotometric method based on the complex of Ga(III) with chrome azurol S and benzyldodecyldimethylammonium bromide and inductively coupled plasma–optical emission spectrometry technique. The total content of gallium in the soils clearly depends on the soil location and properties and ranged from 41.7 to 437 μg g^–1. The contents of gallium determined in 10% nitric acid and 1 M of magnesium chloride extract ranges respectively from 38.0 to 81.9% and 20–40% of the total content of this element. A strong correlation has been found between gallium and zinc, cadmium, lead, and copper. The high Pearson correlation coefficient values and the proportional relationship between the concentrations of Ga and these metals may make it possible to treat gallium as an indicator of soil contamination with heavy metals.     

Heavy-Metal Uptake and Growth of Bouteloua Species in Semi-arid Soils Amended with Biosolids

An experiment was conducted in three wild grass species of Bouteloua genus to compare the effect of application of biosolids on the accumulation of heavy metals, biomass production, and nutrient uptake. Biosolids were applied at rates of 0, 3.5, 7, and 10.5 Mg ha^?1 to two different soil types collected from the southern Chihuahuan Desert. The shoot biomass of B. gracilis (BOGR) and B. scorpioides (BOSC) was two to three times greater than the control while in B. curtipendula (BOCU) in was 75% in both soils. In BOGR, nitrogen and phosphorus uptake were 4–4.5 times greater than the control in calcareous soil. With few exceptions, there was no significant difference of heavy-metal concentrations (copper, chromium, arsenic, nickel, and zinc) in the plant tissues compared to the control. The application of biosolids showed interspecies variability in growth response and nutrient uptake with a minimal risk of heavy-metal uptake for Bouteloua wild species.