Nutrient Loss Following Phragmites australis Removal in Controlled Soil Mesocosms

Mechanisms to remove Common reed (Phragmites australis) typically include a combination of herbicide applications and mechanical cutting or plowing of the soil. The objective of this study was to remove P. australis by various mechanisms and measure the subsequent short-term release of nutrients via simulated rain events. Three rain events of similar duration and intensity were conducted on a control subset and three treatments (above and belowground biomass removal, herbicide application, and basal cut) of soil mesocosms (n?=?6) that were designed to export excess water as either surface runoff or leachate through the soil profile. The dominant pathway for soluble reactive phosphorus (p?<?0.001) and ammonium (p?<?0.001) export were surface runoff while nitrate (p?<?0.001) was leached through the soil profile. More nitrate was exported in the vegetation removal treatments (i.e., biomass removal, herbicide, and basal cut) than the control (p?<?0.001) while more soluble reactive phosphorus was exported in the herbicide and basal cut treatment compared to the control (p?=?0.010). In regards to ammonium, a higher export was observed in the herbicide treatment compared to the control, biomass removal, and basal cut treatments (p?<?0.001). We attribute the higher amount of ammonium export in the herbicide treatment to the fact that the glyphosate herbicide used was in an isopropylamine salt form. After examining pre- and postmanipulation soil cores, there was a larger decrease in extractable ammonium in the control and all treatments compared to soil extractable nitrate, which displayed a smaller decrease and in some treatments actually increased during the course of the experiment. Ultimately, in this study, we observed a strong potential for nitrogen biogeochemistry to occur and the removal of vegetation-enhanced nutrient export.     

明沟排水对盐渍化枣田土壤盐分的影响

[目的]研究明沟排水对盐渍化枣田土壤盐分分布规律的影响,明确明沟排水降盐效应,为提高枣树经济效益和生态防护效应以及盐渍土长期改良治理措施研究提供理论依据。[方法]通过对盐渍化枣田土壤进行调查取样,并对该土样进行水溶性盐含量、电导率、pH值和土壤盐基离子当量比的测定。[结果]同一深度土层,随着与明沟距离的增加,盐基离子含量呈现先降低后增加趋势。距离明沟0m处盐基离子含量最高,之后随距离的增加含量显著降低,在40m处达到最低,40m以后盐基离子含量显著增加。此外,距离明沟40m处土壤盐害作用明显降低,盐基离子类型由NaCl型转变为盐害较轻的CaCl_2型和Na_2SO_4型。[结论]明沟排水降盐效果最佳的范围在40m左右;由于滴灌和离子迁移速率等因素的影响,在土壤表层和底层出现了盐基离子聚集现象。     

Effective Nutrient Sources for Plant Growth on Bauxite Residue: II. Evaluating the Response to Inorganic Fertilizers

An integral part of managing dust emissions from bauxite residue storage areas in Western Australia is the establishment of native vegetation and dust control crops. Recent changes to local health department regulations preclude the routine use of poultry manure, the previous standard fertilizer for growing dust control crops on bauxite residue sand. This paper reports on a field evaluation of different forms of inorganic fertilizer, to assess their effectiveness as alternatives to poultry manure for supplying nutrients to dust control crops. We compared plant growth and nutrient uptake under different forms of nitrogen (N) and phosphorus (P) fertilizers with additional potassium (K) and trace elements. A diammonium phosphate (DAP) based fertilizer blend which supplied 270 kg N ha^?1 of N and 307.5 kg P ha^?1 was found to be more effective than a superphosphate based blend containing the same amounts of these nutrients. The DAP treatment did not respond to topdressing with different N fertilizers, but plant growth in the superphosphate treatment was responsive to topdressing with N. Of the three different nitrogenous fertilizers evaluated for topdressing the superphosphate treatment (ammonium sulphate, diammonium phosphate, and urea), the ammonium based fertilizers were most effective. The DAP blend was the most cost effective of all the fertilizers studied, costing only A$1070 ha^?1 compared with A$2473 ha^?1 for the superphosphate blend and A$1600 ha^?1 for poultry manure. We concluded that the DAP fertilizer blend could be used as an effective replacement for poultry manure for growing dust control crops on bauxite residue sand.     

生物砖排水沟在天然气管道工程植被恢复中的应用

天然气改善了人们日常生活的能源结构,天然气管道的铺设翻山越岭无疑会破坏植被,造成水土流失,需要采取有效的措施及时进行防治。介绍了由深圳市大自然生态园林技术有限公司开发的"生物砖排水沟"专利技术在深圳坪山门站出站管线沿山辐射段天然气管道工程植被恢复中的应用效果,实践证明,生物砖排水沟的生态景观效果好、生态功能强、有利于土壤保墒和植被的恢复、可减缓排水沟内的水流速度、施工进度也不受天气的影响、施工便捷快速、工程造价低,可有效解决植被恢复中的排水问题,具有不可替代的生态和环境效益。     

Partitioning the Nutrient and Nonnutrient Contributions Of Compost to Dryland-Organic Wheat

Organic materials supply nutrients to plants but may also have other, nonnutrient-related benefits which are more difficult to quantify. This study partitioned the winter wheat (Triticum aestivum L.) yield response from compost applications into nutrient and nonnutrient fractions. Composted dairy manure and wheat straw bedding was applied at five rates (0, 10, 25, 50, and 75 Mg dry weight ha^?1) to dry-land wheat in an organic wheat-fallow farming system. The compost was fall-applied and incorporated prior to planting at adjacent sites in sequential years. Maximum grain yield increases from compost application ranged from 2,139 kg ha^?1 in a year with 186% of average annual precipitation to 1,324 kg ha^?1 in a year with 87% of average annual precipitation. The Mitscherlich equation was used to describe the yield response to compost rate. The nutrient and nonnutrient contributions of compost to grain yield were partitioned by solving the Mitscherlich equation for compost rates where applied nutrients were in surplus (≥25 Mg ha^?1), calculating a non-nutrient Mitscherlich response function, and subtracting the nonnutrient response function from the full response to determine the nutrient contribution across compost rates. At the 10 Mg ha^?1 compost rate, the nonnutrient to nutrient yield response ratio varied from 0.25:1 for the year with above average precipitation to 2.2:1 for the year with below average precipitation. Compost significantly increases dry-land wheat yields. These results suggest that nonnutrient benefits of compost applications may be significant and exceed nutrient benefits under dryland production in low rainfall years.     

农田排水沟渠系统对磷面源污染的控制

排水沟渠是农业区重要的水利工程,其排水功能更是农业安全生产的重要保障,然而农田排水沟渠的生态功能未得到足够重视。随着农业面源污染研究的深入,农田排水沟渠在控制磷面源污染上的作用日益引起人们的关注。针对农业面源磷污染控制问题,简要归纳总结了农田沟渠系统对磷面源污染的迁移转化机理及影响因素,并在此基础上,探讨了排水沟渠控制磷污染的措施,以期为农业面源污染控制和管理提供参考。     

山丘区换流站截排水沟布设

以南通道换流站为例,对输变电工程中山丘区换流站站区截排水沟的设置依据及布设位置进行分析,对截排水沟的设置情形进行统计,确保工程能形成完整的截排水系统,有效地减少水土流失。     

Evaluating a Rapid On-Farm Nutrient Determination Model for Use in Implementing Nutrient Management Plans

Government regulatory agencies recommend nutrient management plans (NMPs) for animal operations to reduce non-point source pollution. These plans require manure analysis for total nitrogen (TN) and total phosphorus (TP), and use indices to determine nutrient availability. This study evaluated a rapid on-farm method to predict TN and TP concentrations of swine slurries. A field investigation based on this rapid assessment procedure was used to evaluate the effect of a NMP on corn yield and soil fertility. Manure grab samples were collected to validate the rapid on-farm model for predicting TN and TP. A corn crop was raised on two phosphorus (P) soil test levels (medium and excessive) using three randomized complete blocks with two replications of three treatments. Rapid on-farm models were accurate (P ≤ 0.05) for predicting manure TN and TP. The rapid model manure application rate produced grain yields that were significantly higher than inorganic-N fertilization treatments (13,000 kg ha^?1 versus 9,000 kg ha^?1) (P ≤ 0.05). Potassium chloride extractable soil P and ammonium were not significantly different (P ≥ 0.05) in manure treatments compared with the inorganic-N treatment. Analysis of ear leaf N, P, and K and grain yields demonstrated that the rapid model manure application developed by a NMP met crop requirements.     

Waterlogging Effects on Plant Nutrient Concentrations in Soybean

Previous research has implicated nitrogen (N) deficiency as a major contributor to waterlogging-induced yield loss in soybean [Glycine max. (L.) Merr.]. However, this stress is recognized as also reducing leaf concentrations of other nutrients. The objective of this research was to determine the effect of waterlogging stress on leaf N compared with other macro and micronutrients. A secondary objective was to assess the effects of waterlogging at different developmental stages on soybean yield. Compared with other nutrients [phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), manganese (Mn), zinc (Zn)], N demonstrated the greatest association with waterlogging-induced yield loss. This conclusion was based on concomitant occurrence of decreased yield with decreased N, depression of N below the critical level, and symptomology. Soybean was as sensitive to waterlogging stress when applied at a vegetative stage (V4) compared with reproductive stages (R1, R3, and R5).     

Evidence for the Use of Low-Grade Weirs in Drainage Ditches to Improve Nutrient Reductions from Agriculture

Typical controlled drainage structures in drainage ditches provide drainage management strategies for isolated temporal periods. Innovative, low-grade weirs are anticipated to provide hydraulic control on an annual basis, as well as be installed at multiple sites within the drainage ditch for improved spatial biogeochemical transformations. This study provides evidence toward the capacity of low-grade weirs for nutrient reductions, when compared to the typical controlled drainage structure of a slotted riser treatment. Three ditches with weirs were compared against three ditches with slotted risers, and two control ditches for hydraulic residence time (HRT) and nutrient reductions. There were no differences in water volume or HRT between weired and riser systems. Nutrient concentrations significantly decreased from inflow to outflow in both controlled drainage strategies, but there were few statistical differences in N and P concentration reductions between controlled drainage treatments. Similarly, there were significant declines in N and P loads, but no statistical differences in median N and P outflow loads between weir (W) and riser (R) ditches for dissolved inorganic phosphate (W, 92%; R, 94%), total inorganic phosphate (W, 86%; R, 88%), nitrate-N (W, 98%; R, 96%), and ammonium (W, 67%; R, 85%) when nutrients were introduced as runoff events. These results indicate the importance of HRT in improving nutrient reductions. Low-grade weirs should operate as important drainage control structures in reducing nutrient loads to downstream receiving systems if the hydraulic residence time of the system is significantly increased with multiple weirs, as a result of ditch length and slope.     

Evaluating Nutrient Availability in Semi-arid Soils with Resin Capsules and Conventional Soil Tests,I: Native Plant Bioavailability under Glasshouse Conditions

Resin capsule technology developed for nutrient analysis in agriculture soils recently has been expanded to semi-arid soils without knowledge of effectiveness. This study determined if resin nutrient adsorption is correlated to plant uptake and yield in semi-arid soils. Two soils were treated with five rates of nitrogen (N) and four rates of phosphorus (P), placed in pots with resin capsules, seeded with squirreltail grass (Elymus elymoides), and grown in a glasshouse for 120 d followed by biomass determination and nutrient analysis of capsules, soils, and tissues. Yield and total nutrient uptake were highly correlated to fertilizer application rates, resin ammonium (NH₄)-N, and sodium bicarbonate (NaHCO₃)–extracted P; marginally correlated to resin and potassium chloride (KCl)–extracted nitrate (NO₃)-N, and unrelated to KCl-extracted NH₄-N and resin P. Use of resin capsules to estimate N bioavailability is promising, but P bioavailability is not effectively estimated with resin capsules; instead traditional NaHCO₃ extraction is recommended.     

作物生长与土壤有效养分关系之研究

一、引言观察施用某种肥料,所表现之作物生长状况,及秤其产量而决定某种作物在某种土壤气候及环境下,需要某种肥料概况,此为一般研究肥效之最普通方法。若在田间详细观察作物之生长情况,进而研究生长地土壤内各种肥料有效养分之富缺程度及其他影响因子尚少,著者等认为地面上农作物生长良窳与土壤有效养分之供给有密切之关系,故本此目的在田间详细观察作物生长状况后,即采取土样,加以分析,并施用同样养分量栽培同样作物作对照比较,求其互相关程度,此本研究之目的也。     

Nutrient Composition and Distance from Point Placement to the Plant Affect Rice Growth

Point placement of urea is an efficient technology to improve urea use efficiency in transplanted rice (Oryza sativa L.), but it is largely unknown how nutrient composition in the point placement and the distance from placement site to the plant influence rice root distribution and growth, nutrient uptake, and rice grain yield. A controlled greenhouse experiment was conducted using both N-and P-deficient soil with point placement of N only or N and P together (N + P) at a distance close to or far from the plant, in comparison to an N-spilt application and a no-N control. Both nutrient composition and distance significantly affected rice root growth. Compared with the N point placement, the N + P point placement led to smaller root length and mass densities, higher specific root length (SRL) around the placement site, smaller root system, higher straw mass and grain yield, and higher N and P uptake. The difference between the N + P and N point placements was greater when close to the plant than when far from the plant. It is suggested that higher SRL around the placement site is essential for improving nutrient uptake and rice grain yield, and simultaneous point placement of N and P has a synergistic effect on rice growth.     

植物根系对养分缺乏和毒害的适应及其与养分吸收效率的关系

根系是植物对养分最敏感的部位,直接与养分接触,参与养分的吸收过程,在养分胁迫(缺乏或毒害)下最先引起反应。植物在低氮、低磷、低钾和元素中毒胁迫下,其形态和生理上都发生一定的变化。综述了养分缺乏和元素毒害胁迫下植物根系形态的变化、生理反应、分子生物学基础及其与养分吸收效率和对元素毒害的抗性的关系。     

Ratio of Nutrient and Minerals to Defensive Compounds Indicative of Plant Quality and Tolerance to Herbivory in Pear Trees

The phenolic ester 3-0-trans-p-coumaroyltormentic acid and the volatile compounds (E,E)-α-farnesene and methyl salicylate have been identified previously in pear tree cultivars ‘Bartlett,’ ‘NY10355,’ and ‘Conference.’ Here, using the same dried extract of leaf samples, the contents of total protein, chlorophyll, and the minerals calcium (Ca), magnesium (Mg), phosphorus (P), potassium (K), sodium (Na), carbon (C), and nitrogen (N) were determined. Differences between pear cultivars were found with regard to their absolute content in Ca, K, chlorophyll, and total protein, and to carbon/nitrogen values in uninfested leaves compared with leaves infested by Cacopsylla pyricola (Foester) and C. pyri L. (Homoptera, Psyllidae) on partially and completely infested trees. The ratio of nutrients and minerals to the constitutive and Cacopsylla-induced phenolic and two volatiles reflects a diminution of the leaf quality as food for Cacopsylla nymphs in infested leaves of all cultivars. In uninfested leaves, the magnitude of this ratio in partially infested trees of cv. ‘Conference’ with local response, together with Ca ion content and chlorophyll loss, point to classification of this cultivar as tolerant to herbivory.     

黄河三角洲湿地不同植被群落下土壤养分含量特征

以黄河三角洲潮上带湿地为对象,通过采样、分析,研究了4种典型的植被群落下水盐梯度和土壤养分含量的变化特征。结果显示．沿植物群落演替方向,土壤水分含量无显著差异,土壤盐分呈逐渐降低的趋势,在一定程度上反映了植物群落的不同演替阶段。在这种水盐梯度下,植被群落的变化能够影响土壤养分含量,沿着植被演替方向,全碳与有机质含量随着演替方向呈先逐渐降低后增加的趋势,土壤碳氮比（C／N）在植被演替中期相对较高;全氮含量沿着演替方向呈现增加趋势,硝态氮与铵态氮先增加后降低;全磷与有效磷随演替变化系数较小,演替中期各理化性质变异系数相对较大。各群落土壤C／N值均小于25。相关分析表明,全氮、有机质与有效磷两两显著相关（p〈0.01）,有效磷还与含水率显著相关（p〈0．05）,硝态氮、铵态氮和全磷未显示出与其他理化性质的相关关系。含水率与pH值显著相关（p〈0．05）,且二者均与土壤盐分显著负相关（P〈0．01）。     

Investigation of Effects on Nutrient Uptake of Humic Acid Applications of Different Forms to Strawberry Plant

Abstract

The aim of this study was to investigate the effect of humic acid in liquid and solid form on uptake of nutrients for strawberry grown under greenhouse conditions. The experiment was designed in randomized block design with four replications for two years. Solid form of humic acid (Agrolig) that contained 85% humic acid was applied in the amounts of 0, 100, 200, 300, and 400 kg/ha before planting. Liquid form of humic acid (Blackjak) that contained 15% humic acid was applied by drip irrigation system at the concentrations of 0, 2500, 5000, 7500, and 10,000 mL/ha/month. Along with humic acid, 200 kg/ha nitrogen (N), 100 kg/ha phosphorus (P₂O₅), and 400 kg/ha potassium (K₂O) was applied by drip irrigation system after transplanting. According to the results, N, phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), and copper (Cu) contents of the leaves were not affected significantly by the applications of solid and liquid humic acid forms. Applied liquid humic acid had a significant effect on the zinc (Zn) content of the leaves causing a decrease in the Zn content. Because of having excessive calcareous soil in the experimental area, uptake of nutrients in strawberry plants was not affected significantly. Applications of humic acid at high concentrations had an inhibitory effect on some of the nutrients.     

The Effect of Bat Guano Applied to the Soil in Different Forms and Doses on Some Plant Nutrient Contents

This research was conducted for the purpose of determining the effects of bat guano on plant nutrient contents in the soil and in lettuce (Lactuca sativa L.) during the spring of both 2014 and 2015 with three replications according to randomized blocks experiment design. Bat guano was applied to the soil in two different forms; According to the results organic matter, P, Cu and Mn amounts in the soil were found to be statistically significant and increased compared to the control. Likewise, in the application of bat guano dust, organic matter, P and Mn amounts in the soil were found to be statistically significant and increased compared to the control. In lettuce, N, K, Mg, Fe, Cu, Zn and Mn amounts in the application of bat guano powder and K, Ca, Mg, Fe, Zn and Mn amounts in the application of bat guano dust were found to be statistically significant.