Relation of Toxicity in Corn Seeds Treated with Zinc and Salicylic Acid

The beneficial effect of corn seed treatment with zinc (Zn) is directly related to the source used. The excess of this micronutrient causes seedling stress and reduces growth. Thus, assuming that the use of exogenous phytohormones can minimize such effects, we evaluated different doses and sources of Zn for the treatment of maize seeds with or without salicylic acid. The experiment took place in the laboratory, and two factorial experiments, 2 × 4 + 1, were performed in a randomized design. The seeds were treated with either ZnO or ZnSO₄ at doses of 0.5, 1, 2, and 3 g.kg^?1 seed with four replications, differing only by the addition of 4.14 mg L^?1 salicylic acid. Treating seeds with Zn and salicylic acid did not affect germination. ZnO led to a greater increase in dry mass in corn seedlings as compared with zinc sulfate, especially at higher doses (2 and 3 g kg^?1 seed). Seed treatment with sulfate reduces root and shoot length, and salicylic acid did not attenuate this toxic effect. Dry mass is not affected when oxide is used. Salicylic acid reduces the accumulation of zinc in the treatment of corn seeds, regardless of the source used.     

Distribution of Total and DTPA‐Extractable Zinc,Copper, Manganese,and Iron in Vertisols of India

Abstract

Vertisols of India are developed over isohyets of 600 to 1500 mm, and their chemical cycles are set by drainage, landforms, and particle size, which results in variable pedogenic development within the otherwise homogeneous soils. The purpose of this study was to identify pedogenic processes in the distribution of total and DTPA‐extractable zinc (Zn), copper (Cu), manganese (Mn), and iron (Fe). The soils are developed over basaltic parent material of Cretaceous age. Soil samples were drawn from genetic horizons of the 13 benchmark profiles and analyzed by using HF–HClO₄ acid for total and DTPA extraction. Correlation coefficients were calculated taking all samples together. The total concentration varied from 24 to 102 mg kg^?1 for Zn, 21 to 148 mg kg^?1 for Cu, 387 to 1396 mg kg^?1 for Mn, and 2.36 to 9.50% for Fe. Their variability was proisotropic and haplodized, and their concentrations increased with advancing isohyets. Within the isohyets, hindrance in drainage caused retention of Zn and Cu but loss of Fe. The piedmont soils had more Fe than alluvium soils. The spatial distribution of total contents of Zn, Cu, and Fe was influenced by the pedogenic processes associated with Haplusterts but not with provenance materials. Surface concentrations of the elements by biotic lifting and/or harvest removal were negated by the pedoturbation that further contributed to the irregular distribution of the elements in the profiles. Total Zn and total Cu had positive coefficients of correlations with coarse clay, whereas total Mn and total Fe were positively correlated with fine clay. The DTPA‐extractable forms were functions of isohyets and drainage and showed association with organic carbon content and coarse clay.     

Micronutrients Losses from Soil under Subsurface Drainage System

The drainage system, although it reclaims waterlogged soils, poses a potential threat to leaching of valuable nutrients. To assess the micronutrient losses from such system established more than two decades ago in the plains of northwestern Pakistan, drainage waters were periodically analyzed for selected micronutrients. The inputs of micronutrients in irrigation waters were also determined. The micronutrient removal in drainage water was 1.39 to 9.79 times greater than micronutrient inputs in irrigation waters and fertilizers. Among micronutrients, the removal of copper (Cu) and manganese (Mn) in drainage water was greater than iron (Fe) and zinc (Zn). The concentrations of micronutrients generally changed with cropping (sampling time), increased with soil depth, and were invariably negative on the nutrient balance sheet, suggesting that these nutrients are continuously depleted from the system in drainage water. These nutrients therefore must be replenished in soil through an appropriate means for optimum crop yields under the given drainage–irrigation–cropping system.     

Surface Liming and Zinc Availability in a Long‐Term Experiment under No‐Till System

No‐till (NT) system with crop rotation is one of the most effective strategies to improve agricultural sustainability in tropical and subtropical regions. To control soil acidity in NT, lime is broadcast on the surface without incorporation. The increase in soil pH due to surface liming may decrease zinc (Zn) availability and its uptake by crops. A field experiment was performed in Paraná State, Brazil, on a loamy, kaolinitic, thermic Typic Hapludox to evaluate Zn bioavailability in a NT system after surface liming and re‐liming. Dolomitic lime was surface applied on the main plots in July 1993 at the rates of 0, 2, 4, and 6 Mg ha^?1. In June 2000, the main plots were divided in two subplots to study of the effect of surface re‐liming at the rates of 0 and 3 Mg ha^?1. The cropping sequence was soybean [Glycine max (L.) Merrill] (2001–2 and 2002–3), wheat (Triticum aestivum L.) (2003), soybean (2003–4), corn (Zea mays L.) (2004–5), and soybean (2005–6). Soil samples were collected at the following depths: 0–0.05, 0.05–0.10, and 0.10–0.20 m, 10 years after surface liming and 3 years after surface re‐liming. Soil Zn levels were extracted by four extractants: (i) 0.005 mol L^?1 diethylenetriaminepentaacetic acid (DTPA) + 0.1 mol L^?1 triethanolamine (TEA) + 0.01 mol L^?1 calcium chloride (CaCl₂) solution at pH 7.3 (DTPA–TEA), (ii) 0.1 mol L^?1 hydrochloric acid (HCl) solution, (iii) Mehlich 1 solution, and (iv) Mehlich 3 solution. Zinc concentrations in leaves and grains of soybean, wheat, and corn were also determined. Soil pH (0.01 mol L^?1 CaCl₂ suspension) varied from 4.4 to 6.1, at the 0‐ to 0.05‐m depth, from 4.2 to 5.3 at the 0.05‐ to 0.10‐m depth, and from 4.2 to 4.8 at the 0.10‐ to 0.20‐m depth, after liming and re‐liming. Zinc concentrations evaluated by DTPA–TEA, 0.1 mol L^?1 HCl, Mehlich 1, and Mehlich 3 solutions were not changed as a result of lime rate application. Re‐liming increased Zn concentrations extracted by 0.1 mol L^?1 HCl at 0–0.05 m deep and by DTPA–TEA at 0.05–0.10 m deep. Surface‐applied lime promoted a decrease in Zn concentrations of the crops, mainly in grains, because of increased soil pH at the surface layers. Regardless of the liming treatments, levels of Zn were sufficient to soybean, wheat, and corn nutrition under NT.     

The use of iron chelates in compound fertilizers containing trace elements

Abstract

The chemical behaviour of iron chelates, incorporated in compound fertilizers with inorganic micronutrient compounds, was studied. Pot experiments were conducted to evaluate the effectiveness of these products in controlling iron deficiency. A commercial compound fertilizer, containing 0.09% Fe as Fe‐DTPA, 0.12% Cu, 0.16% Mn and 0.04% Zn as sulfates, proved to be ineffective in preventing iron chlorosis in Chamaecyparis lawsoniana ’Alumii’, growing on sphagnum peat at two lime levels. The same fertilizer formulation with 0.09%‐ Fe as Fe‐EDDHA did prevent iron chlorosis at both lime levels. Fe‐EDTA, incorporated in the compound fertilizer, gave good results at the lower but not at the higher lime level, due to the low stability of Fe‐EDTA at high pH. Data from laboratory experiments showed that copper replaced the chelated iron in the compound fertilizer containing Fe‐DTPA, causing the iron to precipitate. The strong competition between copper and iron for the organic ligand is due to a specific affinity of copper for DTPA, resulting in a copper chelate with high stability constant and a molar ratio of copper to chelating agent of 2 : 1.

In the case of Fe‐EDDHA and Fe‐EDTA the competition between iron and copper is much weaker. In contrast to Fe‐DTPA, these chelates remain rather stable when incorporated in fertilizers containing micronutrients.     

Low efficiency of Zn uptake and translocation in plants provide poor micronutrient enrichment in rice and soybean grains

Abstract

Recent research has shown the need for an in-depth knowledge of zinc biofortification of cereal and oilseed grains due to its importance to human nutrition. However, little is known about the Zn dynamics in plant–soil system. In this work, we evaluated the effect of soil-applied Zn on the absorption, translocation, and compartmentalization of Zn in rice (Oryza sativa L.) and soybean (Glycine max L. Merrill) plants. The soil used in the greenhouse experiment was fertilized with zinc chloride (ZnCl₂) at rates of 0, 1, 2, 4, and 8?mg Zn kg^?1. The source of Zn was labeled by ⁶⁵Zn with specific activity of 185.5 kBq mg^?1 Zn. The amount of Zn derived from fertilizer and its use in each plants compartment was determined by direct method in isotopic calculations. Rice and soybean plants presented low efficiency in the absorption from soil-applied Zn. The accumulated Zn in the panicle, pod, and grains was not modified, due to its low translocation in the plant. The Zn uptake in rice plants was from 1.34 to 4.60?mg pot^?1 in shoots and just 0.81 to 1.43?mg pot^?1 translocated to panicles. Soybean plants presented Zn uptake between 2.36 and 4.68?mg pot^?1 in shoots, out of which 0.19 to 0.34?mg.pot^?1 and 0.48 to 0.57?mg pot^?1 translocated to grains and pods, respectively. The nutrient utilization from fertilizer was low, with mean values of 12 and 8.7% for rice and soybean plants, respectively. Soil-applied Zn showed low capacity for enriching rice panicle and soybean pod or grain probably due low Zn uptake and translocation.     

Biochar application to temperate soils: Effects on soil fertility and crop growth under greenhouse conditions

Biochar (BC) application as a soil amendment has aroused much interest and was found to considerably improve soil nutrient status and crop yields on poor, tropical soils. However, information on the effect of BC on temperate soils is still insufficient, with effects expected to differ from tropical soils. We investigated the effects of BC on soil nutrient dynamics, crop yield, and quality in a greenhouse pot experiment. We compared three agricultural soils (Planosol, Cambisol, Chernozem), and BCs of three different feedstocks (wheat straw [WS], mixed woodchips [WC], vineyard pruning [VP]) slowly pyrolyzed at 525°C, of which the latter was also pyrolyzed at 400°C. The BCs were applied at two rates (1% and 3%, which would correspond to 30 and 90 t ha^–1 in the field). Three crops, namely mustard (Sinapis alba L.), barley (Hordeum vulgare L.), and red clover (Trifolium pretense L.) were grown successively within one year. The investigated soil properties included pH, electrical conductivity (EC), cation‐exchange capacity (CEC), calcium‐acetate‐lactate (CAL)–extractable P (P_CAL) and K (K_CAL), C, N, and nitrogen‐supplying potential (NSP). The results show a pH increase in all soils. The CEC increased only on the Planosol. The C : N ratio increased at 3% application rate. Despite improving the soil nutrient status partly, yields of the first crop (mustard) and to a lesser extent of the second crop (barley) were significantly depressed through BC application (by up to 68%); the yield of clover as third crop was not affected. Only the BC from WS maintained yields in the range of the control and even increased barley yield by 6%. The initial yield reduction was accompanied by notable decreases (Cu, Fe, Mn, Zn) and increases (Mo) in micronutrient concentrations of plant tissues while nitrogen concentrations were hardly affected. The results of the pot experiment show that despite additional mineral fertilization, short‐term growth inhibition may occur when applying BC without further treatment to temperate soils.     

桃源县植烟土壤微量元素与烟叶常规化学成分相关性分析

为探究土壤微量元素与烟叶常规化学成分的关联程度,及为提高烟叶质量提供理论依据,运用描述统计、简单相关和典型相关统计分析方法,研究了湖南省桃源县烟区植烟土壤微量元素与烟叶常规化学成分的关系。结果表明,桃源县烟区土壤中铁、锰、锌、铜、硼和钼含量平均值均在适宜范围及以上水平;土壤有效铜含量与烟叶中钾含量呈极显著负相关;土壤有效硼含量与烟叶中还原糖、总糖、氯含量和糖碱比呈极显著正相关,与总氮、蛋白质含量和钾氯比呈极显著负相关;土壤有效钼含量与还原糖含量、总糖含量和糖碱比呈极显著负相关,与总氮和蛋白质含量呈极显著正相关;土壤微量元素含量对烟叶常规化学成分的影响为有效硼>有效钼>有效锰>有效锌>有效铁>有效铜。通过典型相关分析表明,随着桃源县土壤有效锰和有效硼含量的减少或者有效钼含量的增加,能够引起烤后烟叶烟碱、总氮、蛋白质含量和钾氯比的增加以及还原糖、总糖、氯含量和糖碱比的降低。     

黑土土壤质量演变初探III——不同地区黑土主要微量元素状况及其评价

以不同地区黑土阳离子微量元素的全量及有效态含量变化为研究内容 ,重点讨论和评价了锌、锰、铜和铁的分布状况、变化规律和丰缺程度。研究结果表明 :公主岭、海伦和北安地区黑土全锌、全锰、全铜和全铁平均含量与1980年第二次土壤普查结果基本一致 ;有效锌、有效锰、有效铜和有效铁的平均含量都高于缺素的临界值 ,说明3个地区黑土中目前不会出现严重的微量元素缺乏的现象。除北安地区有效铜含量低于1980年第二次土壤普查结果外 ,其他地区微量元素有效含量都有所提高 ,一般顺序为 ,公主岭<海伦<北安。黑土中微量元素与其他理化形状之间的相关性在不同地区表现不同 ,但有效锌、有效铜和有效铁含量与黑土中有机质含量之间存在一定的正相关。因此 ,在目前情况下 ,黑土中有机质水平可以基本上反映出微量元素的丰缺程度。     

复合肥与微量元素配施对玉米产量和品质的影响

采用盆栽试验研究了复合肥与微量元素配施对玉米产量和品质的影响，结果表明：复合肥配施复合微肥、硫酸锌等微量元素能明显促进植株的生长发育，增加籽实产量；但与稀土配施对植株的生长发育及籽实产量无明显影响。复合微肥与微量元素配施对玉米的品质有不同的影响：复合微肥对可溶性糖的影响较大，硫酸锌对总淀粉的影响较大，而稀土对总淀粉、可溶性糖及粗蛋白的影响均较大。因此，建议复合肥厂家在生产N、P、K三元素复合肥时最好填加复合微肥及硫酸锌。