Behavior of Iodine in a Forest Plot,an Upland Field and a Paddy Field in the Upland Area of Tsukuba,Japan. Iodine Concentration in Precipitation,Irrigation Water,Ponding Water and Soil Water to a Depth of 2.5 m

In the course of a series of studies conducted to investigate the long-term behavior of ¹²⁹I (which has a half-life of 16 million years) in the environment, the concentration of stable iodine (¹²⁷I) in precipitation, irrigation water and soil water to a depth of 2.5 m in a forest plot, an upland field and a paddy field in the upland area of Tsukuba, Japan, was determined. In the forest plot, the mean iodine concentrations in soil water at all the depths ranged from 0.13 to 0.21 μg L^?1, about one-tenth of the values recorded in precipitation (weighted mean 2.1 μg L^?1). This finding suggests that the major part of iodine in precipitation was sorbed onto the surface soil horizon under oxidative conditions. In the upland field, the mean iodine concentration in soil water was 2.2 μg L^?1 at a depth of 0.2 m and it decreased to 0.34–0.44 μg L^?1 at a depth of 0.5 m or more; these concentrations were about one-fifth of that in precipitation. This suggested that the major part of the iodine derived from precipitation was sorbed onto the subsurface soil horizon (at depths between 0.2 and 0.5 m). In the paddy field, during the non-irrigation period, the mean iodine concentrations in soil water at all the depths ranged from 1.8 to 4.8 μg L^?1, almost the same values as those recorded in precipitation. During the irrigation period, the mean iodine concentrations at depths of 0.2 and 0.5 m were 18.8 and 16.7 μg L^?1, values higher than the 10.9 μg L^?1 value recorded in irrigation water and the 11.8 μg L^?1 value recorded in ponding water. However, at a depth of 1.0 m or more, the mean iodine concentrations in soil water rapidly decreased from 7.3 to 1.8 μg L^?1. These data suggested that a significant amount of iodine flowed out from the paddy field by surface runoff and a considerable amount of iodine that leached to a depth of 0.5 m was retained onto the mildly oxidative soil horizon (2Bw) that lay at depths between 0.5 and 1.0 m. At a depth of 2.5 m in the paddy field, the mean iodine concentration in soil water decreased to 1.8 μg L^?1, but this level was much higher than those in the forest plot and upland field at the same depth, which suggested that a significant amount of iodine had leached into the groundwater-bearing layer. There was a negative correlation (r=-0.889) between the E_h of soil and the iodine concentration in soil water (0.2 m depth) of the paddy field. Particularly, when the E_h of soil fell below approximately 150 mV, the iodine concentration rapidly increased to above 10μg L^?1. As for the chemical forms of iodine in precipitation, irrigation water, ponding water and soil water during the winter irrigation period in the paddy field with oxidative conditions, 58–82% of iodine consisted of IO^? ₃ and 17–42% of iodine consisted of I^?. In the soil water during the summer irrigation period in the paddy field under reductive conditions, 52–58% of iodine consisted of I^?, and 42–47% consisted of IO^? ₃.     

包膜控释肥料在旱地农田的应用研究进展与展望

就国内外控释肥料在旱地农田中的应用效果、田间养分释放,以及高效施用做了综述,重点总结了控释肥料在不同作物上的增产效果和当前应用研究中存在的问题。施用控释肥料可以提高肥料利用率,减少氮素淋溶损失,并具有增加作物产量和改善蔬菜品质的优点,但控释肥料应用中也存在着养分在土壤中的转化和去向不明,养分释放与作物生长对应性差,忽视环境条件对养分释放影响等问题。并对今后高效施用控释肥的技术研究进行了展望。     

Phosphorus Use Efficiency in Upland Rice Genotypes Under Field Conditions

Phosphorus (P) deficiency is one of the most yield limiting factors for crop production in South American soils. Upland rice (Oryza sativa L.) is an important crop in South American cropping systems, including Brazil. A field experiment was conducted with the objective to evaluate 20 upland rice genotypes for phosphorus (P) use efficiency. The P rate used was low (0 kg P ha^?1) and high [87 kg P ha^?1 or 200 kg phosphorus pentoxide (P₂O₅) ha^?1]. Plant height, shoot dry weight, grain yield, panicle number, 1000 grain weight, spikelet sterility, and grain harvest index were significantly influenced by P and genotype treatments. The P X genotype interaction was significant for grain yield, indicating that genotypes responded differently under two P rates. Overall, grain yield increased by 12% with the addition of P fertilization. Based on grain yield efficiency index, genotypes were classified into efficient, moderately efficient, and inefficient group. The genotypes that were classified as efficient in P use were BRA032048, BRA042094, BRA02601, BRA032051, BRA032033, BRA052015, BRA042156, BRA01600, BRA01506, BRA052023 and BRA042160. The inefficient genotypes in P us efficiency were BRS Primavera, BRA052045, BRA01596, and BRS Sertaneja. Grain harvest index had a significant positive association with grain yield and spikelet sterility had a significant negative association with grain yield, as expected. Average, P-use efficiency of five genotypes was about 17 kg kg^?1 (kg grain yield per kg P applied).     

南方红壤稻田与旱地土壤有机碳及其组分的特征差异

大量研究证明稻田土壤比旱地土壤更具固碳潜力,但至今对稻田土壤固碳机制的认识尚不甚清楚。本研究于2007年利用两个开垦年代相似,近20多年分别一直种植双季稻和双季玉米的长期定位试验,来比较不同种植模式下土壤有机碳及其组分的差异。结果表明,水田土壤总有机碳和总氮的浓度分别是旱地的2.2倍和2.5倍。与试验前相比,水稻种植显著提高了土壤有机碳的含量,增幅达到30.8%,而旱地的前后差异不显著。在所有团聚体粒径水平上,水田有机碳的浓度均显著高于旱地。其中53～250μm微团聚体相差最大,水田是旱地的近3倍。水田微团聚体保护碳（iPOM_m）在土壤中的浓度是旱地的4.2倍,微团聚体保护碳在总有机碳中的比重也显著高于旱地,达到25.5%,是旱地的2倍。水田和旱地iPOM_m组分碳的差异能够解释其总有机碳差异的42.8%。上述结果可以增强我们对稻田土壤固碳机制的了解,为稻田土壤碳管理提供理论依据。     

土体重构对旱田土壤微生物及养分的影响

以旱田土壤为研究对象,探讨常规耕作(CK),0-10cm与10-20cm土层置换(TC1),0-20cm与20-40cm土层置换(TC2),0-30cm与30-60cm土层置换(TC3),0-10cm土层混合(GF1),0-20cm土层混合(GF2),0-30cm土层混合(GF3)对不同层次土壤微生物量、酶活性及土壤养分含量的影响。结果表明,与CK处理相比,土体重构处理能够显著提高土壤微生物量碳氮含量和土壤酶活性,不同层次土壤酶活性与对照处理差异显著;耕翻处理的土壤酶活性明显高于对照处理,但除土壤脲酶含量和GF2处理均未达到显著水平;土层置换处理土壤养分含量随土层深度增加表现出不同的变化趋势,与对照处理相比各层次差异显著,土层置换处理有利于土壤养分含量在不同土层中的均匀分布;土层置换处理对土壤改良效果明显,可提高土壤微生物量碳氮含量,增加土壤酶活性,活化土壤养分。     

西南丘陵区坡地土壤水分的时空变异

利用地统计学方法研究了我国西南丘陵区坡地土壤水分特性的时空变异特性。土壤水分含量在不同季节和不同层次具有一定的空间结构,可用纯块金效应模型、指数模型和球状模型进行拟合;土壤平均含水量、剖面各层含水量和半方差参数除变程外均随季节表现出明显的变化,但随土壤层次无明显的变化规律;土壤含水量的空间相关性随季节呈波动变化,块金值的变化趋势与基台值相似。克立格插值结果显示不同季节土壤平均含水量的空间分布格局不同。     

Nitrogen,Phosphorus and Potassium Interactions in Upland Rice

Upland rice is an important crop in South America, including Brazil. Nutrient interactions are important in determining crop yields. A greenhouse experiment was conducted to evaluate interaction among nitrogen (N), phosphorus (P), and potassium (K) in upland rice production. The treatments applied to upland rice grown on an Oxisol were three levels of N (N₀, N₁₅₀ and N₃₀₀ mg kg^?1), three levels of P (P₀, P₁₀₀ and P₂₀₀ mg kg^?1) and three levels of K (K₀, K₁₀₀ and K₂₀₀ mg kg^?1). These treatments were tested in a 3 × 3 × 3 factorial arrangement. Grain yield, shoot dry weight, plant height, root dry weight, maximum root length, panicle number, 1000-grain weight, and grain harvest index were significantly influenced by N, P, and K treatments. The treatment that did not receive P fertilization did not produce panicle or grain. Hence, P was most yield-limiting nutrient compared to two other nutrients. At the N₀P₀K₀ treatment, rice did not produce grains, indicating severe deficiency of these nutrients in Brazilian Oxisols. Maximum grain yield was obtained with the N₃₀₀P₂₀₀K₂₀₀ treatment. Grain yield had significant positive association with plant height, shoot dry weight, root dry weight, maximum root length, 1000-grain weight, panicle number, and grain harvest index. Among these growth and yield components, shoot dry weight had the highest positive association with grain yield and root length minimum positive association with grain yield. Hence, adopting adequate soil and crop management practices can improve growth and yield components and increase grain yield of upland rice.     

运用乙炔抑制-静态土柱培养法测定旱地土壤氮素反硝化损失

介绍了测定土壤反硝化作用的乙炔抑制 -静态土柱培养法 ,并就其应用中的一些条件进行了说明 ,内容包括土柱的取样深度、土柱取样量、土柱培养方式及基本操作程序等。最后阐述了这一方法在北京郊区土壤上的使用情况。     

Mercury and Methylmercury in Upland and Wetland Acid Forest Soils of a Watershed in NE-Bavaria,Germany

Mercury (Hg) and methylmercury (CH₃Hg⁺) are global pollutants, but little information is available on their distribution and mobility in soils and catchments of Central Europe. The objective of this study was to investigate the pools and mobility of Hg and CH₃Hg⁺ in different forest soils. Upland and wetland forest soils, soil solutions and runoff were sampled. In upland soils the highest contents of total-Hg were found in the Oh layer of the forest floor (>400 ng g^-1) and the storage of non geogenic total-Hg (calculated for 60 cm depth) was about 120 mg/m². The storage of total-Hg was one order of magnitude lower in wetland soils as compared to the upland soils. By far the largest proportion of total-Hg in soils was bound in immobile fractions. The depth gradients of CH₃Hg⁺ did not correspond to those of total-Hg and the highest contents of CH₃Hg⁺ in upland soils were observed in the litter layer of the forest floor and in the Bsv horizon. The CH₃Hg⁺ content of the wetland soils was generally much higher in comparison with upland soils. CH₃Hg⁺ in solution was found in the forest floor percolates of upland soils and in wetland soils, but not in soil solutions from mineral soil horizons. Gaseous losses of Hg as well as methylation of Hg are likely in wetland soils. The latter might be highly relevant for CH₃Hg⁺ levels in runoff.     

施肥结构对旱地红壤有机质和物理性质的影响

研究了有机肥与化肥配施对旱地红壤有机质和物理性质的影响。结果表明,虽然部分年份各处理土壤有机质含量存在某些程度的波动,但总体上随施肥年限的延长呈增加趋势;与对照处理相比,有机肥能够显著地提高土壤有机质含量。本田还田是该地区提高土壤有机质含量的最佳方法。有机肥施用均可显著地降低红壤旱地土壤容重,提高土壤孔隙度;但不同的种类之间存在一定差异,即秸秆和本田还田的效果优于厩肥和绿肥的。与化肥处理相比,施用有机肥显著地促进了土壤中>1mm和1～0.5mm水稳性团聚体的形成,厩肥和绿肥处理中>1mm水稳性团聚体含量也显著高于秸秆及本田还田处理的。各种有机肥之间及其与对照相比0.5～0.25mm水稳性团聚体含量都存在不同程度的差异。有机肥的施用不仅显著地提高了0.25～0.05mm微团聚体含量,而且显著地降低了0.05～0.002mm微团聚体含量。除本田还田处理外,其它处理的<0.002mm微团聚体含量与对照相比差异显著。     

Yield,Potassium Uptake,and Use Efficiency in Upland Rice Genotypes

Potassium (K) is an essential nutrient for higher plants. Information on K uptake and use efficiency of upland rice under Brazilian conditions is limited. A greenhouse experiment was conducted with the objective to evaluate influence of K on yield, K uptake, and use efficiency of six upland rice genotypes grown on Brazilian Oxisol. The K rate used was zero (natural soil level) and 200 mg K kg^–1 of soil. Shoot dry weight and grain yield were significantly influenced by K level and genotype treatments. However, K × genotype interactions were not significant, indicating similar responses of genotypes at two K levels for shoot dry weight and grain yield. Genotypes produced grain yield in the order of BRS Primavera > BRA 01596 > BRSMG Curinga > BRS 032033 > BRS Bonança > BRA 02582. Potassium concentration in shoot was about sixfold greater compared to grain, across two K levels and six genotypes. However, K utilization efficiency ratio (KUER) (mg shoot or grain yield / mg K uptake in shoot or root) was about 6.5 times greater in grain compared to shoot, across two K level and six genotypes. Potassium uptake in shoot and grain and KUER were significantly and positively associated with grain yield. Soil calcium (Ca), K, base saturation, acidity saturation, Ca saturation, K saturation, Ca/K ratio, and magnesium (Mg)/K ratio were significantly influenced by K application rate.     

Zinc,Copper, Boron and Iron Requirement of Upland Rice Grown on a Brazilian Oxisol

Deficiency of micronutrients increasing in field crops, including upland rice in recent years. The objective of this study was to determine requirement of zinc (Zn), copper (Cu) boron (B) and iron (Fe) for upland rice grown on a Brazilian Oxisol. The levels used were: Zn (0, 10, 20, 40, and 80 mg kg^?1), Cu (0, 5, 10, 20 and 40 mg kg^?1), B (0, 5, 10, 20 and 40 mg kg^?1) and Fe (0, 250, 500, 1000, and 2000 mg kg^?1). Plant height, straw yield, grain yield, panicle number and grain harvest index (GHI) were significantly improved with the addition of these micronutrients. Root growth was also improved with the application of micronutrients, except with the addition of B. Maximum grain yield was obtained with the addition of 51 mg Zn, 24 mg Cu, 5 mg B kg^?1, and 283 mg Fe kg^?1 soil. Similarly, maximum straw yield was obtained with the addition of 38 mg Zn, 17 mg Cu, 6 mg B kg^?1, and 1500 mg Fe kg^?1 soil. Maximum plant height was obtained with the addition of 54 mg Zn, 10 mg B kg^?1, and 1197 mg Fe kg^?1 soil. Copper did not affect plant height significantly. Maximum panicle number was obtained with the addition of 22 mg Cu kg^?1, 3 mg B kg^?1, and 1100 mg Fe kg^?1 soil. Zinc did not affect panicle number significantly. Maximum GHI was obtained with the addition of 61 mg Zn kg^?1, and 8 mg B kg^?1. Zinc was had a linear increase in GHI in the range of 0 to 80 mg kg^?1, and Fe showed a negative relationship with GHI.     

Diagnostics,Genesis, and Localization of Pedosediments within a Small Catchment (Central Russian Upland)

Eurasian Soil Science - Results of a detailed analysis of pedosediments—sediments composed of transported material of soil humus horizons—are discussed. Five main morphological features...     

旱地土壤中的硝化-反硝化作用

本文综述了国内外旱地土壤硝化 -反硝化作用的过程及其影响因数和硝化 -反硝化作用产生的N2 O量及其影响因素以及旱地土壤上氮肥硝化 -反硝化损失量等方面的研究进展     

Growth,Nutrient Uptake,and Use Efficiency in Dry Bean in Tropical Upland Soil

Dry bean (Phaseolus vulgaris L., cv. ‘BRS Requinte’) is an important legume crop and nutrient availability is one of the most yields limiting factors for bean production in tropical upland soils. A greenhouse experiment was conducted in Brazilian Oxisol to study growth, nutrient uptake, and use efficiency of macro- and micronutrients during growth cycle of bean plant. Plants were harvested at 15, 30, 45, 60, 73, and 99 days after sowing for determination of growth parameters and uptake of nutrients. Root dry weight, shoot dry weight and leaf trifoliate increased significantly (P< 0.01) in a quadratic fashion with the advancement of plant age. However, root-shoot ratio decreased significantly with increasing plant age. Concentrations of nitrogen (N), calcium (Ca), magnesium (Mg), and zinc (Zn) decreased with the advancement of plant age. However, concentrations of phosphorus (P), potassium (K), copper (Cu), and manganese (Mn) increased significantly with the advancement of plant age. Accumulation of macro- and micronutrients significantly increased with the increasing plant age. Accumulation of N, P, K and Cu was higher in the grain compared with root and shoot, indicating relatively higher importance of these nutrients in improving grain yield of dry bean. Nitrogen, P and Cu use efficiency was higher for shoot weight compared to grain weight. For grain production, nutrient use efficiency was in the order of Mg > Ca > P > K > N for macronutrients and Cu > Zn = Mn for micronutrients.     

Upland development policy,livelihood change and land degradation: interactions from a Laotian village

This study uses a local political ecology approach that examines the physical and social dimensions of land use and soil erosion and their broader political and socioeconomic environment in Ban Lak Sip, a village located in the uplands of the Luang Prabang Province in Laos. The study indicates that, despite an explicit government policy aimed at improving both socioeconomic and environmental conditions, the resulting livelihood change has in part led to a deterioration in working conditions with mixed impacts on the environment. While land degradation and economic transition appear to have driven villagers to rework the role and importance of the land in their livelihoods, this paper argues that the Laotian rural development policy has constrained the adaptation process and led to a significant intensification in labour and land use. In fact, Ban Lak Sip villagers have had to adapt both to actual land degradation processes and to a discourse on upland environmental degradation constructed by the Laotian State and international development actors. The results of this study have significant implications for the formulation of environmental policy and for land degradation research more widely. Copyright © 2006 John Wiley & Sons, Ltd.     

Availability of Cadmium and Zinc as Affected by the Use of Reactive Phosphate Rock,Lime, and Chicken Manure on an Indonesian Acidic Upland Soil under Field Conditions

We assessed cadmium (Cd) and zinc (Zn) availability when applying reactive phosphate rock (RPR) in combination with lime and chicken manure on Indonesian acidic upland soils. Maize plants were grown on unamended soil and soils treated with several combinations of 2 tons dolomite ha^–1, 2 tons of chicken manure ha^–1, 1 ton ha^–1 of RPRL (reactive phosphate rock containing 4 mg Cd kg^–1 and 224 mg Zn kg^–1), and 1 ton ha^–1 of RPRH (RPR containing 69 mg Cd kg^–1 and 745 mg Zn kg^–1). In addition to its positive effect on plant yield, application of RPR in combination with chicken manure did not result in toxic Cd concentrations. Although liming is effective to reduce plant Cd concentrations, it results in more soil Cd accumulation and more plant Zn deficiency. Cadmium and Zn concentrations in shoots and grains can be predicted well from amounts extracted from the soil by 0.5 M ammonium (NH₄) acetate + 0.02 M ethylenediaminetetraacetic acid (EDTA) at pH 4.65.     

Iodine biofortification in tomato

Iodine is an essential element in the human diet, and iodine deficiency is a significant health problem. No attempts to increase iodine content in plant‐derived food (biofortification) have so far been particularly effective. We studied iodine uptake in tomato (Solanum lycopersicum L.) to evaluate whether it is possible to increase the iodine concentration in its fruits. Iodine translocation and storage inside tomato tissues were studied using radioactive iodine. Potassium iodide was also supplied at different concentrations to tomato plants to evaluate the resulting iodide concentration both in the vegetative tissues and the fruits. The results indicate that iodine was taken up better when supplied to the roots using hydroponically grown plants. However, a considerable amount of iodine was also stored after leaf treatment, suggesting that iodine transport through phloem also occurred. We found that tomato plants can tolerate high levels of iodine, stored both in the vegetative tissues and fruits at concentrations that are more than sufficient for the human diet. We conclude that tomato is an excellent crop for iodine‐biofortification programs.     

Yield,Uptake, and Retranslocation of Nutrients in Banana Plants Cultivated in Upland Soil of Central Amazonian

ABSTRACT

Banana cultivation is considered one of the most important agricultural activities of economic and social importance in Brazil. The objective of this work was to investigate the uptake, retranslocation and the effect of fertilization on the yield and uniformity of banana bunches (Musa spp.) cultivated in Central Amazonian, region with approximately 1.5 million km² or 150 million hectares. Two experiments were conducted in a Xanthic Ferralsol (dystrophic Yellow Latosol), the predominant soil of the region, examining: i) the nutrient uptake and translocation rate in twelve plants; and ii) the efficiency of zinc use, in a completely randomized blocks in a 4×2 factorial scheme in split plot design with four zinc sulfate (ZnSO₄) rates (0, 30, 60, and 120 g plant^?1 cycle^?1) and two application times (in the hole together with the seedling or as surface broadcast in the fifth month after planting), with four replicates. Uptake of macronutrients was in the order of potassium (K) > nitrogen (N) > calcium (Ca) > magnesium (Mg) > phosphorus (P) and micronutrients in the order of manganese (Mn) > iron (Fe) > boron (B) > zinc (Zn) > copper (Cu). The N, P, K, Mg, and Cu have a high retranslocation rate compared to other nutrients investigated. The bunch yield increased significantly in a quadratic fashion with increasing Zn rate and hole application method of zinc was more efficient compared to broadcast application. At high concentration, Zn presents a low mobility in the phloem from the leaves to the fruits. The critical leaf concentration of zinc at the start of inflorescence was 12.9 mg kg^?1.