Effect of silicon amendment on soil-cadmium availability and uptake in rice grown in different moisture regimes

Greenhouse experiments were conducted to study the effects of silicon on soil-cadmium availability and uptake in rice grown in an acid soil maintained under two different moisture regimes (field capacity or submergence). The silicon treatment decreased the cadmium concentration and uptake in grain and straw, while it increased the cadmium uptake in roots of plants grown on cadmium contaminated soil. Cadmium availability in soil decreased with increase in silicon applied in soil due to the rise in soil pH. The results suggest that the reduction of soil-cadmium availability could be due to cadmium immobilization caused by calcium silicate-induced pH rise in the soils. The decrease in cadmium concentration and uptake in grain and straw could be attributed to the silicon-mediated distribution of cadmium that resulted in the increased accumulation of toxic cadmium in the roots more than the edible parts of the rice plants.     

粉垄耕作提高土壤养分有效性并促进甘蔗维管组织发育和养分吸收

[目的]研究粉垄耕作对宿根蔗和新植蔗生长过程中土壤养分含量、甘蔗对养分吸收以及植株解剖形态的影响,为粉垄耕作技术推广提供理论依据.[方法]以桂糖42号为供试材料进行田间试验,以常规耕作为对照(CK,耕作深度25 cm),粉垄耕作(垂直旋深40 cm)为处理,甘蔗种植采用新植甘蔗和宿根两种方法.在甘蔗主要生育期,采集植株...     

Liming an acid soil treated with diverse silicon sources: Effects on silicon uptake by sugarcane (Saccharum spp. hybrids)

Highly weathered soils are typically acid, with low plant-available silicon (Si), and may also be high in soluble aluminum (Al). We tested whether pre-liming an acid soil prior to silicate fertilizer application improved Si uptake by sugarcane (Saccharum spp. hybrids), feasibly through elimination of reactive Al. Three trials with potted sugarcane were grown in an acid soil. Treatments included 11 different Si sources and 1- or 3-month pre-liming periods. Soil and plant tissue Si content and yield were determined. Pre-liming for a 1- or 3-month period did not increase plant Si uptake and reduced available soil Si throughout. Alkaline Si sources produced significantly more plant-available Si and greater plant uptake than non-alkaline sources. Silicon and lime treatments did not significantly increase yield. We conclude that pre-liming an acid soil before Si application is unlikely to significantly improve Si uptake by sugarcane.     

白浆土型水稻土施硅肥对水稻产量及品质的影响

采用田间试验,研究了在白浆土型水稻土上不同硅肥施用量对水稻产量和品质的影响.结果表明,白浆土型水稻土上最佳的硅肥施用量为600kg/hm2,增产8.43%.随着施肥量的增加,穗数、穗粒数均表现出增加的趋势,以施用量450一750 kg/hm2效果较明显.施用硅肥后,稻米的糙米率提高的幅度不大,以600 kg/hm2处理为最大,比对照高出0.34%,而精米率和整精米率比对照高0.36%和3.37%;垩白度、垩白率均以150 kg/hm2处理为最小,分别比对照低8.89% 1.91%;胶稠度和蛋白质含量均以450 kg/hm2处理为最高,分别比对照高3.49%和16%.     

红壤蔗区土壤有效态钾的空间变异研究

应用地统计学方法分析了农场尺度的红壤蔗区土壤表层的土壤速效钾、缓效钾的空间分布结构。结果表明,研究区域内的土壤速效钾和缓效钾含量都存在极强的空间相关性,在整个区域的空间分布具有相似性。缓效钾的协同克立格法的插值精度高于普通克立格法。研究结果可为甘蔗的钾肥精准管理提供依据。     

The oxidation of soil organic matter by KBrO for particle size determination

Abstract

The oxidation of soil humus by alkaline KBrO solution at boiling temperature has been shown to be successful even with samples as carbonaceous underwater soils. With these soils treatment with H₂O₂ produces a cohesive foam which prevents further oxidation.     

A contemporary overview of silicon availability in agricultural soils

Our current understanding of silicon (Si) availability in agricultural soils is reviewed and knowledge gaps are highlighted. Silicon is a beneficial rather than essential plant nutrient and yield responses to its application have been frequently demonstrated in Si‐accumulator crops such as rice and sugarcane. These crops are typically grown on highly weathered (desilicated) soils where soil solution Si concentrations are low. Increased yields are the result of simultaneous increases in plant tolerance to a wide range of biotic (plant pathogens, insect pests) and abiotic (water shortage, excess salts, metal toxicities) stresses. Traditionally, soil solution Si is viewed as being supplied by dissolution of primary and secondary minerals and buffered by adsorption/desorption of silicate onto Al and Fe hydrous oxide surfaces. In recent years it has become recognized that phytogenic cycling of Si [uptake of Si by plants, formation of phytogenic silica (SiO₂ · nH₂O) mainly in leaves and subsequent return of this silica to soils in plant litter] is the main determinant of soil solution Si concentrations in natural forests and grasslands. Considerable diminution of the phytogenic Si pool in agricultural soils is likely due to regular removal of Si in harvested products. A range of extractants (unbuffered salts, acetate‐based solutions, and acids) can provide valuable information on the Si status of soils and the likelihood of a yield response in rice and sugarcane. The most common Si fertilizers used are industrial byproducts (e.g., blast furnace slag, steel slag, ferromanganous slag, Ca slag). Since agriculture promotes soil desilication and Si is presently being promoted as a broad spectrum plant prophylactic, the future use of Si in agriculture is likely to increase. Aspects that require future research include the role of specific adsorption of silicate onto hydrous oxides, the significance of phytogenic Si in agricultural soils, the extent of loss of phytogenic Si due to crop harvest, the role of hydroxyaluminosilicate formation in fertilized soils, and the effect of soil pH on Si availability.     

丘陵红壤蔗区土壤有机质的时空变异特征

采用地统计学和GIS相结合的方法，研究了甘蔗连作19年(1980～1999年)的低丘陵红壤蔗区土壤有机质含量的时空变异特征。研究结果表明：由于土壤侵蚀和土地利用格局的影响，1980年的土壤有机质与地形坡度为极显著负相关。在长期甘蔗连作下，地形坡度对1999年的土壤有机质空间分布已没有影响，而有机肥施用的侧重方向使得土壤有机质与经纬度、海拔高度都有相关性。土壤有机质的时空变异与蔗区耕作管理的精细化程度有关，精细化程度高的高产蔗区的土壤有机质平均降幅为11％，而精细化程度低的低产蔗区土壤有机质则平均增幅为50％。大量施用源自甘蔗的有机肥已造成蔗区土壤养分的不平衡。     

砂壤土上甘蔗管理的土壤质量指示评估

An important factor for the sustainability of soils highly susceptible to degradation is the use of monitoring tools that promptly and realistically reflect changes imposed on soil by different cropping systems. To select soil quality indicator variables in sugarcane (Saccharum officinarum L.) production areas that fulfill the criteria of sensitivity to management practices and between-season consistency in the management discrimination, ten composite soil samples (0-10 cm) were collected in July 2005 (rainy season) and again in March 2006 (dry season) from areas under cultivation of organic sugarcane (OS), green sugarcane (GS), burned sugarcane (BS) and from an adjacent native forest (NF) area at Usina Triunfo, Boca da Mata, Alagoas, Brazil. Microbial biomass-C (MBC), total organic C (TOC), soil enzyme activity expressed as the rate of fluorescein diacetate (FDA) hydrolysis, mean weight diameter of water-stable soil aggregates (MWD), and percentage of water-stable macroaggregates (PWSA) were analyzed. Although MBC and TOC were higher in NF than in the cultivated areas, no differences were observed in these C pools between the three sugarcane systems. The response of FDA to the site management was dependent on the sampling time. In the rainy period, the activity followed the order: NF > OS > GS > BS, whereas in the dry season, only NF differed from the other treatments. Irrespective of the sampling time, MWD and PWSA decreased in the order NF > OS = GS > BS. The variables MWD and PWSA are quite sensitive for discriminating between site management histories regardless the sampling season.     

两种不同土壤条件下可培养甘蔗内生固氮菌的多样性

为明确不同土壤条件对甘蔗内生固氮菌多样性的影响,对分别种植在红壤土和水稻土的4个甘蔗品种的内生固氮菌进行分离和鉴定,并利用数学生态学方法分析不同来源内生固氮菌的多样性。结果表明,从红壤土的甘蔗组织中分离筛选获得23个内生固氮菌株,它们在基于16S r DNA序列分析结果上属于9个不同的菌属;而从水稻土的甘蔗组织中获得59个内生固氮菌株,分类上属于19个不同的菌属。群落生态学分析结果显示,来源于水稻土的甘蔗内生固氮菌的群落丰富度指数(dma)、多样性指数(H')以及均匀度指数(Jsw)均明显高于红壤土,表明水稻土条件下的甘蔗内生固氮菌群落结构相对复杂、稳定和均匀;而相同土壤条件下4个甘蔗品种间的内生固氮菌丰富度指数和多样性指数差异并不明显。本研究结果反映了土壤生态条件是影响甘蔗内生固氮菌多样性的重要因子。     

Suitability of extractant for soil available silicon and silicon response to upland paddy grown on alkaline soils of central India

Abstract

Several silicon (Si) extractants are being employed in different countries mostly for lowland acidic soils. Present investigation was conducted to evaluate suitable extractants for upland paddy grown on alkaline soils. Available Si was extracted by using ten different extractants. Tris buffer pH 7.0 (1:10) in Inceptisols showed positively highest and significant correlation with grain yield (r?=?0.870), grain Si uptake (r?=?0.887), straw yield (r?=?0.852), and straw Si uptake (r?=?0.919). However, 0.5?M acetic acid (1:2.5) in Vertisols showed positively highest and significant correlation with grain yield (r?=?0.810), grain Si uptake (r?=?0.852), straw yield (r?=?0.850), and straw Si uptake (r?=?0.929). The application of Si @ 200?kg ha^?1 along with chemical fertilizers significantly increased yield and nutrient uptake of upland paddy on Vertisols. Tris buffer pH 7.0 (1:10) and 0.5?M acetic acid (1:2.5) were suitable extractant for Inceptisols and Vertisols, respectively based on its correlation with yield and nutrient uptake.     

Effect of biochar amendment on soil‐silicon availability and rice uptake

Rice growth and its resistance to pests had been often constrained by soil‐silicon (Si) availability. The purpose of this study was to assess the potential of biochar soil amendment (BSA) to improve Si availability in paddy soils. A cross‐site field trail with BSA was conducted in six locations with different climatic and crop‐production conditions across S China. Plant‐available Si content before field‐trials establishment and after rice harvest, as well as Si content in rice shoot were determined. Varying with site conditions, plant‐available Si content of soil was observed to increase significantly with BSA in most sites. Significant increase in rice shoot Si was detected in four out of the six sites, which was well correlated to the concurrent increase in soil pH under BSA treatment. This study demonstrates an important role of BSA to improve Si availability and uptake by rice mainly through increasing soil pH of the acid and slightly acid rice soils.     

硅、镁、硼肥对甘蔗产量和产糖量影响的研究

在硅、镁、硼营养较缺乏的甘蔗田，进行硅肥、镁肥、磷肥的施肥效应试验，结果表明：硅、镁、硼肥及其不同施肥水平对甘蔗的株高、茎径、锤度、产量和产糖量有明显的影响。施用硅肥使甘蔗锤度、产量和理论产糖量分别比对照增加0.42～1．11，11．04～14．96t／hm^2和1．84～2．10t／hm^2；施用镁肥分别比对照增加0.93～1．26，4．02～9．55t／hm^2和0．99～1．53t／hm^2；施用硼肥分别比对照增加0．41～1．20，5．00～10．00t／hm^2和0．80～1．82t／hm^2。     

我国水稻土的硅素营养研究

硅能够改善土壤肥力、促进水稻生长发育、提高生物量和改善品质,在水稻生产上意义重大,所以水稻土是硅素研究的重点。本文着重硅素对水稻的增产机理及硅素营养研究进行综述。     

Evaluation of extractants for predicting availability of sulphur to mustard in inceptisols

Abstract

Mustard (Brassica juncea) is an important oilseed crop of northern India, which is widely grown in Delhi and adjoining States. This crop has a relatively high requirement of sulphur (S), and is sensitive to S‐deficiency. For predicting response of mustard to S application, several extractants have been tried with variable results. Since selection of a promising extractant for a particular soil needs careful consideration, the present investigation was planned to select the most promising extractant to predict the availability of S to mustard grown on Inceptisols of Delhi. For this purpose, a greenhouse experiment was conducted with twenty soils (two from each often important soil series from the cultivated alluvial soil belt of Delhi. Nine extractants, commonly used for estimating the availability of S, were evaluated and S in soil extract and in plant digest was estimated using the turbiditimetric method. The results indicate that the phosphate salt methods extracted comparatively more S than other extractants. The amount of S extracted by these extractants was found in the following order: KH₂PO₄‐500 ppm P>Ca(H₂PO₄)₂‐500 ppm P>0.001 M HCl>NaOAc+HOAc>heat soluble S>0.15% CaCl₂>l% NaCl> water soluble S>NH₄OAc+HOAc. Simple correlation coefficients of the amounts of S extracted by different extractants and the forms of S with the plant parameters were worked out. To determine the combined effect of soil characteristics on S extraction by different extractants, stepwise multiple regression analysis was carried out. Based on this study, the suitability of the extractants for mustard crops in Inceptisols of Delhi may be arranged as follows: 0.15% CaCl₂>water soluble S>0.001 M HCl>Ca(H₂PO₄)₂‐500 ppm>1%NaCl>NH₄OAc+HOAc>NaOAc+HOAc>KH₂PO₄‐500 ppm P>heat soluble S.     

Evaluation of four soil test extractants for Zimbabwe soils

Abstract

The objective of this research was to compare the results from anion exchange Resin extraction of P, and the acidified ammonium acetate (AA) extraction of K and Mg with the results obtained using two single extraction procedures, Mehlich 1 (M‐l) and Mehlich 3 (M‐3). Phosphorus extracted from 72 Zimbabwe soils using M‐l and M‐3 was comparable to Resin extracted P in about 80% of the soils. Mehlich 1 extracted about half the amount of P as the Resin method, and M‐3 extracted about one and one‐half times as much. Phosphorus by M‐3 was highly correlated, (r — 0.846), with Resin extracted P from soils having 0.01M CaCl₂ pH values of equal to or greater than 5.9. On soils less than pH 5.9, the r value was 0.502, and for all soils, the r value for M‐3 vs Resin P was 0.615. Mehlich 1 extracted P vs Resin P had a r value of 0.298. Acidified ammonium acetate (AA) extraction of K and Mg was comparable to M‐l and M‐3 extraction of K and Mg in 92% or more of the 72 soils. The K correlation coefficient (r) for AA vs M‐l and AA vs M‐3 was 0.918 and 0.944, respectively. The Mg correlation coefficient (r) for AA vs M‐l and AA vs M‐3 was 0.940 and 0.962, respectively.     

甘蔗四种下种方式的效果比较研究

采用广西推广面积最大的桂糖１１号和正积极推广的新台糖１６号两个甘蔗品种作试验材料,分砍种浸种消毒（Ａ）,砍种不浸种（Ｖ）,剥叶不砍种（Ｃ）,不剥叶不砍种（Ｄ）４种下种方式。试验结果表明,在前期土壤水分及温度基本满足甘蔗萌芽与生长要求的条件下,两个甘蔗品种均以砍种浸种消毒种茎处理的出苗早、出苗率高,糖１１号Ａ处理出苗率比Ｂ、Ｃ、Ｄ处理高２７．０％￣６４．７％,新台糖１６号Ａ处理出苗率比Ｂ、Ｃ、Ｄ处理     

施肥技术对甘蔗产量和品质的影响

在每hm^2施鱼粉有机-无机复混肥1500kg的大田生产条件下，采用随机区组设计，设置5种施肥技术处理，研究其对甘蔗农艺性状、生理生化特性、蔗茎产量及品质等方面的生长效应。结果表明：D处理蔗茎产量和含糖量最高，D处理与A处理的蔗茎产量差异达显著水平，含糖量差异达极显著水平；D处理与B、C、E处理间的含糖量差异达显著水平；其他处理间差异不显著。