Adaptive attributes of tropical forage species to acid soils II. Differences in shoot and root growth responses to varying phosphorus supply and soil type

Identification of plant attributes that improve the performance of tropical forage ecotypes when grown as monocultures or as grass+legume associations in low fertility acid soils will assist the development of improved forage plants and pasture management technology. The present work compared the shoot and root growth responses of four tropical forages: one grass and three legumes. The forages were grown in monoculture or in grass+legume associations at different levels of soil phosphate. Two infertile acid soils, both Oxisols, were used: one sandy loam and one clay loam. They were amended with soluble phosphate at rates ranging from 0 to 50 kg ha^‐1. The forages, Brachiaria dictyoneura (grass), Arachis pintoi, Stylosanthes capitata and Centrosema acutifolium (legumes), were grown in large plastic containers (40 kg of soil per container) in the glasshouse. After 80 days of growth, shoot and root biomass production, dry matter partitioning, leaf area production, total chlorophyll content in leaves, soluble protein in leaves, root length, and proportion of legume roots in grass+legume associations were determined. The grass, grown either in monoculture or in association responded more to phosphorus supply than did the three legumes in terms of both shoot and root production. At 50 kg ha^‐1 of phosphorus, the grass's yield per plant in association was greatly enhanced, compared with that of grass in monoculture. The increase in size of grass plants in association compared with that in monoculture may have been caused by reduced competition from the legumes. These differences in shoot and root growth responses to phosphorus supply in acid soils between the grass and the three legumes may have important implications for improving legume persistence in grass+legume associations.     

NUTRIENT UPTAKE AND USE EFFICIENCY BY TROPICAL LEGUME COVER CROPS AT VARYING PH OF AN OXISOL

Oxisols comprise large soil group in tropical America. These soils are acidic and have low fertility. Use of tropical legume cover crops in cropping systems is an important strategy to improve fertility of these soils for sustainable crop production. Data are limited on nutrient uptake and use efficiency of tropical cover crops under different acidity levels. The objective of our study was to evaluate growth and nutrient uptake parameters of sixteen tropical legume cover crops under three soil pH (5.1, 6.5, and 7.0) of an Oxisol. Shoot dry weight was influenced significantly by pH and cover crop treatments and their interactions, indicating that cover crops used had differential responses to changing soil pH levels. Overall, shoot dry weight decreased when soil pH was raised from 5.1 to 7.0, indicating acidity tolerance of cover crops. Nutrient concentration (content per unit of dry weight), uptake (concentration X dry weight), and nutrient use efficiency (dry weight of shoot per unit of nutrient uptake) varied significantly among cover crops. The variation in nutrient uptake and use efficiency among cover crop species was associated with variation in shoot dry matter production. Significant variation among crop species in dry matter production and low C/N ratios (average value of 14.25) suggest that cover crops which produced higher dry matter yield like white jack bean, gray mucuna bean, black mucuna bean, mucuna bean ana, and lablab are important choices for planting in tropical soils to recover large amount of macro and micronutrients, and to prevent such nutrient leaching in soil plant systems.     

土壤质地对柱花草生长发育、生物量及土壤肥力变化的影响

采用大田试验的方法,在云南省元谋县小雷宰流域内壤土、砂壤土和重壤土3种质地土壤上,以热研5号柱花草为材料,研究土壤质地对柱花草生长发育、生物量及土壤有机质、有机碳、全氮和全磷的影响。试验结果表明:3种土壤质地上种植柱花草,柱花草地上部和地下部生长量和生物量表现幼苗期增加缓慢,而分枝期后增加快的趋势。壤土耕性好,兼有砂土和重壤土的优点,有利柱花草地上部分的生长发育,柱花草地上部生长量、生物量及改善土壤肥力方面显著高于重壤土。砂壤土有利于柱花草根系向深层土壤生长,柱花草地下部生长量、生物量及根瘤显著高于种植在重壤土。在3种土壤质地种植柱花草后,土壤有机质、有机碳、全氮和全磷均有上升趋势。综合而言,通气性和保肥保水能力居中的壤土更适合柱花草的生长发育及干物质的积累。     

Effect of dicyandiamide on growth and nutrient uptake of cotton

Abstract

The nitrification inhibitor dicyandiamide (DCD) offers potential for improving efficiency of N applications to cotton grown on sandy soils of the southeastern Coastal Plain. Research has indicated that cotton is sensitive to DCD. The purpose of this greenhouse experiment was to investigate the effect of DCD on growth and nutrient uptake of DPL 90 cotton grown for 73 days in pots containing a typical Coastal Plain soil (Norfolk sandy loam, Typic Paleudult). Nitrogen (50 mg kg^‐1) as NaNO₃ or urea, and DCD (0, 2.5, 5, 10, 15 and 20 mg kg^‐1) were applied to the soil at first true leaf and plants were harvested 58 days later. Sodium nitrate increased leaf dry weight and total dry weight of plants 9.1 and 6.0%, respectively, over urea fertilized plants. Leaf area, dryweight, and stem dry weight were reduced linearly with DCD. Fertilization with urea increased concentrations of leaf P, K, and Mn and reduced the concentration of Mg in leaf tissue. Dicyandiamide increased leaf N, P, and K concentrations but reduced concentrations of Ca, Mg, and Mn. Uptake rates (μg^‐1 g^‐1 fresh root day^‐1) of Ca and Mg were increased 7.5 and 13.7%, respectively, with NaNO₃ vs. urea, while P uptake rate was 15.5% greater for urea‐fertilized plants vs. NaNO₃‐fertilized plants. Dicyandiamide reduced Ca and Mg uptake rates. Phosphorus uptake rates were increased by DCD when urea was the N source. The effects of DCD on cotton growth and nutrient uptake generally resulted from the compound itself and were not an indirect result of nitrification inhibition. Although significant reductions in plant growth did not occur unless DCD exceeded that normally applied with recommended N rates on this soil, these results suggest a need for caution when applying DCD to cotton grown on sandy soils.     

Effect of nitrate/ammonium ratio on biomass production,nitrogen accumulation,and use efficiency in sorghums of different origin

Plant nitrogen (N) uptake, growth, and N use efficiency may be affected by N form (NO₃ ^‐or NH₄ ⁺) available to the root. The objectives of this study were to determine the effect of mixed N form on dry matter production and partitioning, N uptake, and biomass N use efficiency defined as total dry matter produced per unit plant N (NUE₁) in U.S. and tropical grain sorghums [Sorghum bicolor (L.) Moench]. The U.S. derived genotype CK 60 and three tropical genotypes, Malisor‐7, M 35–1, and S 34, were evaluated in a greenhouse trial using three nutrient solutions differing in their NO₃ ^‐/NH₄ ⁺ ratio (100/0, 75/25, 50/50). Shoot and root biomass, N accumulation, and NUE, were determined at 10‐leaf and boot stages. Averaged over all genotypes, shoot and root biomass decreased when NH₄ ⁺ concentration was increased in the solution. Shoot biomass was reduced by 11% for 75/25 and 26% for 50/50 ratios, as compared to 100/0 NO₃ ^‐/NH₄ ⁺. Similarly, root biomass reduction was about 34% and 45% for the same ratios, respectively. Increasing NH₄ ⁺ concentration also altered biomass partitioning between shoot and root as indicated by decreasing root/shoot ratio. Total plant N content and NUE₁ were also reduced by mixed N source. Marked genotypic variability was found for tolerance to higher rates of NH₄ ⁺. The tropical line M 35–1 was well adapted to either NO₃ ^‐ as a sole source, or to an N source containing high amounts of NH₄ ⁺. Such a characteristic may exist in some exotic lines and may be used to improve genotypes which do not do well in excessively wet soil conditions where N uptake can be reduced.     

Interactive effects of substrates and ectomycorrhizal colonization on growth of a poplar clone

A balsam poplar clone (Populus trichocarpa cv. Weser 6) was inoculated by two ectomycorrhizal strains (Laccaria bicolor MW 158 and Paxillus involutus 1444) in Kick‐Brauckmann‐pots. The substrates were two arable sandy soils (Cambisols) with different organic matter content and nutrient supply. One soil (WIL) was rich in organic matter (C_org = 1.6%) and total nitrogen (N_t = 0.14%), whereas the other soil (RIE) had low contents of C_org (0.8%) and N_t (0.08%). Leaf nutrient concentrations, shoot lengths, root and shoot biomass production and nitrogen accumulation in the biomass were determined to discover possible inoculation effects. Mycorrhization indices (% colonized fine roots) of 36% with Laccaria bicolor and 40% with Paxillus involutus were observed on the C_org rich soil (WIL) in contrast to 16% and 14% on the C_org poor soil (RIE), respectively. Inoculation of poplar on the soil WIL increased shoot length, biomass production, shoot:root ratio and total N uptake of the cuttings, whereas on the soil RIE only the shoot:root ratio increased and the N nutrition was improved. We conclude that interactions between soil and fungus should be tested when choosing ectomycorrhizal strains for inoculation.     

Soil Aluminum Effects on Growth and Nutrition of Cacao

In acid soils, Al toxicity and nutrient deficiencies are main constraints for low yield of cacao (Theobroma cacao L.). A controlled growth chamber experiment was conducted to evaluate the effect of three Al saturations (0.2, 19, and 26%) adjusted by addition of dolomitic lime on growth and nutrient uptake parameters of cacao. Overall, increasing soil Al saturation decreased shoot and root dry weight, stem height, root length, relative growth rate, and net assimilation rate. However, increasing soil Al saturation increased leaf area, specific leaf area (total leaf area/total leaf dry wt), and leaf area ratio (total leaf area/shoot+root wt). Increasing soil Al saturation decreased uptake of elements. Nutrient influx (IN) and transport (TR) decreased significantly for K, Ca and Mg, and showed an increasing trend for S and P as soil Al saturation increased. However, increasing soil Al saturation significantly increased nutrient use efficiency ratio (ER, mg of shoot weight produced per mg of element in shoot) of Ca, Mg and K and decreased ER for other elements. Reduction of soil acidity constraints with addition of lime and fertilizers appear to be key factors in improving cacao yields in infertile, acidic, tropical soils.     

Path and Correlation Analyses of the Factors affecting Biomass Production of Brassica Cultivars under Phosphorus‐Deficiency Stress Environment

Abstract

Path analysis is a statistical technique that partitions correlations into direct and indirect effects and distinguishes between correlation and causation, whereas correlation in general measures the extent and direction (positive or negative) of a relationship occurring between two or more variables. The estimates of correlation and path coefficients can help us to understand the role and relative contribution of various plant traits in establishing growth behavior of crop cultivars under given environmental conditions. Dependence of shoot dry‐matter (SDM) production of six hydroponically grown Brassica cultivars on various growth parameters and characteristics of P metabolism was investigated using the modified Johnson's nutrient solution to maintain deficient (10 µM) and adequate (200 µM) P levels. Root dry‐matter (RDM), total dry‐matter, P content in shoot, and P‐utilization efficiency (PUE) had significant and positive effects on production of SDM in a P‐deficient environment. Root–shoot ratio (RSR), however, negatively affected SDM of cultivars exposed to P‐deficient conditions and did not show any impact on SDM production in either of the two treatments. In a pot study, six Brassica cultivars were grown in a sandy loam soil that was deficient in NaHCO₃‐extractable P (3.9 mg P kg^?1 soil) for 49 days. Significant positive correlations were observed between SDM and some other plant traits such as RDM, leaf area per plant, P uptake, and PUE, at both genotypic and phenotypic levels. The correlations of SDM with RSR, however, were not observed, implying that relative partitioning of biomass into roots or shoots had little role to play in SDM production by Brassica cultivars under P‐deficiency stress. Path analysis revealed that favorable impact of RDM and leaf area on SDM production was indirect through positive effect of these parameters on P uptake and PUE. Thus, under P‐deficiency stress, better P acquisition and efficient P utilization by the cultivars for biomass synthesis collectively formed the basis of higher SDM production by the cultivars, evidencing that P uptake and utilization efficiency are two important plant traits for selecting P‐deficiency‐stress‐tolerant Brassica cultivars.     

Soil Aluminum Effects on Growth and Nutrition of Cacao

In acid soils, Al toxicity and nutrient deficiencies are main constraints for low yield of cacao ( Theobroma cacao L.). A controlled growth chamber experiment was conducted to evaluate the effect of three Al saturations (0.2, 19, and 26%) adjusted by addition of dolomitic lime on growth and nutrient uptake parameters of cacao. Overall, increasing soil Al saturation decreased shoot and root dry weight, stem height, root length, relative growth rate, and net assimilation rate. However, increasing soil Al saturation increased leaf area, specific leaf area (total leaf area/total leaf dry wt), and leaf area ratio (total leaf area/shoot+root wt). Increasing soil Al saturation decreased uptake of elements. Nutrient influx (IN) and transport (TR) decreased significantly for K, Ca and Mg, and showed an increasing trend for S and P as soil Al saturation increased. However, increasing soil Al saturation significantly increased nutrient use efficiency ratio (ER, mg of shoot weight produced per mg of element in shoot) of Ca, Mg and K and decreased ER for other elements. Reduction of soil acidity constraints with addition of lime and fertilizers appear to be key factors in improving cacao yields in infertile, acidic, tropical soils.     

Growth and nutrient uptake in grain sorghum grown under mulch

Mulches can alter plant growth by changing the soil environment, but their effects on mineral uptake in grain sorghum are unknown. A 3‐year study was conducted to measure nutrient uptake in plants grown under 0, 2200, 4400, and 8800 kg/ha mulch. Plants were irrigated to insure that moisture was not limiting. Dry‐matter production, total mineral uptake and concentrations were determined at 7‐ to 9‐leaf, late boot, soft dough, and physiological maturity growth stages. Mulches altered sorghum growth by delaying plant maturity and by increasing dry‐matter yields. Nutrient uptake increased with increased dry‐matter production although elemental concentrations declined. Hybrid reaction to mineral uptake was dependent on the specific environment created by the mulch. Hybrids did not respond the same to given mulch rates each year. Management considerations for soil fertility under mulch conditions should be made on the basis of expected dry‐matter yields for the specific environment.     

热带农业生态系统土壤肥力与植物养分综合管理研究进展

The greatest challenge for tropical agriculture is land degradation and reduction in soil fertility for sustainable crop and livestock production.Associated problems include soil erosion,nutrient mining,competition for biomass for multiple uses,limited application of inorganic fertilizers,and limited capacity of farmers to recognize the decline in soil quality and its consequences on productivity.Integrated soil fertility management(ISFM) is an approach to improve crop yields,while preserving sustainable and long-term soil fertility through the combined judicious use of fertilizers,recycled organic resources,responsive crop varieties,and improved agronomic practices,which minimize nutrient losses and improve the nutrient-use efficiency of crops.Soil fertility and nutrient management studies in Ethiopia under on-station and on-farm conditions showed that the combined application of inorganic and organic fertilizers significantly increased crop yields compared to either alone in tropical agro-ecosystems.Yield benefits were more apparent when fertilizer application was accompanied by crop rotation,green manuring,or crop residue management.The combination of manure and NP fertilizer could increase wheat and faba bean grain yields by 50%–100%,whereas crop rotation with grain legumes could increase cereal grain yields by up to 200%.Although organic residues are key inputs for soil fertility management,about 85% of these residues is used for livestock feed and energy;thus,there is a need for increasing crop biomass.The main incentive for farmers to adopt ISFM practices is economic benefits.The success of ISFM also depends on research and development institutions to provide technical support,technology adoption,information dissemination,and creation of market incentives for farmers in tropical agro-ecosystems.     

土壤紧实度对伴矿景天生长及镉锌吸收性的影响研究

采集黏土、壤黏土和砂质壤土,分别设置无压实、低紧实度及高紧实度3种处理,通过盆栽试验研究了土壤紧实度对Cd、Zn超积累植物伴矿景天生长和Cd、Zn吸收性的影响。结果表明,与无压实处理比较,砂质壤土、壤黏土和黏土中伴矿景天地上部生物量在低紧实度下显著下降66.8%~83.5%、59.9%~60.4%和57.9%~71.4%;高紧实度处理却显著提高了伴矿景天的根系活力(142%~241%)。高紧实度处理显著降低了壤黏土上伴矿景天地上部Cd和Zn含量,但低紧实度对砂质壤土和黏土上伴矿景天地上部Cd和Zn含量无显著影响。与无压实处理比较,低紧实度显著降低了砂质壤土、壤黏土和黏土上伴矿景天的Cd吸取量,分别下降50.4%~73.8%、61.4%~74.9%和43.4%~63.3%,Zn吸取量下降48.7%~79.5%、73.6%~79.0%和46.1%~63.5%;土壤紧实度对壤黏土上伴矿景天的镉锌吸取效率影响最明显。     

Growth and nutrient uptake of temperate perennial pastures are influenced by grass species and fertilisation with a microbial consortium inoculant

Background: The low fertility of sandy soils in South‐Western Australia is challenging for the establishment of temperate perennial pastures. Aims: To assess whether microbial consortium inoculant may improve plant growth by increasing nutrient supply, root biomass and nutrient uptake capacity. Methods: Five temperate perennial pasture grasses–cocksfoot (Dactylis glomerata L. cv. Howlong), phalaris (Phalaris aquatica L. cv. Atlas PG), tall fescue (Festuca arundinacea L. cv. Prosper), tall wheatgrass (Thinopyrum ponticum L. cv. Dundas), and veldt grass (Ehrharta calycina Sm. cv. Mission) were tested in a controlled environment on the growth and nutrition with the microbial consortium inoculant and rock mineral fertiliser. Results: Veldt grass produced the highest shoot and root growth, while tall fescue yielded the lowest. Rock mineral fertiliser with or without microbial consortium inoculant significantly increased root and shoot biomass production across the grass species. The benefit of microbial consortium inoculation applied in conjunction with rock mineral fertiliser was significant regarding shoot N content in tall wheatgrass, cocksfoot and tall fescue. Shoot P and K concentrations also increased in the five grass species by microbial consortium inoculation combined with rock mineral fertiliser in comparison with the control treatment. Arbuscular mycorrhizal (AM) colonisation decreased with rock mineral fertilisation with or without microbial consortium inoculant except in cocksfoot. Conclusions: The response to microbial consortium inoculation, either alone or in combination with rock mineral fertiliser, was plant species‐dependent, indicating its potential use in pasture production.     

Earthworms as drivers of the competition between grasses and legumes

Grasses and legumes are grown together worldwide to improve total herbage yield and the quality of forage, however, the causes of population oscillations of grasses and legumes are poorly understood. Especially in grasslands, earthworms are among the most important detritivore animals functioning as ecosystem engineers, playing a key role in nutrient cycling and affecting plant nutrition and growth. The objectives of the present greenhouse experiment were to quantify the effects of earthworms on grass–legume competition in model grassland systems at two harvesting dates – simulating the widespread biannual mowing regime in Central European grasslands.The presence of earthworms increased the productivity of grasses and legumes after 6 weeks but only that of grasses after another 10 weeks. In mixed treatments, the presence of grasses and earthworms decreased legume shoot biomass, the amount of nitrogen (N) in shoot tissue and the number of legume flowerheads while the presence of legumes and earthworms increased the amount of N in grass shoots and the infestation of grasses with aphids. Analyses of ¹⁵N/¹⁴N ratios indicate that, compared to legumes, grasses more efficiently exploit soil mineral N and benefit from legume presence through reduced “intra-functional group” competition. In contrast to previous experiments, we found no evidence for N transfer from legumes to grasses. However, legume presence improved total herbage and N yield.Earthworms likely modulate the competition between grasses and legumes by increasing soil N uptake by plants and thereby increasing the competitive strength of grasses. Earthworms function as essential driving agents of grass–legume associations by (I) increasing grass yield, (II) increasing the amount of N in grass hay, (III) increasing the infestation rate of grasses with aphids, and (IV) potentially reducing the attractiveness of grass–legume associations to pollinators.     

Coupling of dry matter and nutrient accumulation in forage grass

Abstract

The logistic model has proven very useful in relating dry matter production of forage grasses to applied nitrogen. A recent extension of the model coupled dry matter and plant ? accumulation through a common response coefficient c. The objective of this analysis was to establish the validity of the extended model for each of the three major nutrients (?, ?, ?), with a common coefficient c between dry matter and each applied nutrient. Analysis of variance established the validity of this hypothesis. The model accurately described response of dry matter, plant nutrient removal, and plant nutrient concentration to applied nutrient, with overall correlation coefficients of 0.9928, 0.9972, and 0.9975 for applied N, P, and K, respectively. Furthermore, the model closely described the relationship between yield and plant nutrient removal, as well as between plant nutrient concentration and plant nutrient removal, for each nutrient. This work confirmed earlier results for applied ? with various grasses and established the validity of the model for applied ? and ? for the first time. The logistic equation is well‐behaved and simple to use on a pocket calculator. It can be used to describe yields and nutrient removal in evaluation of agricultural production and environmental quality.     

Eucalyptus growth and phosphorus nutritional efficiency as affected by soil compaction and phosphorus fertilization

ABSTRACT

Soil compaction interferes in soil nutrient transport and root growth. The aim of this work was to evaluate eucalypt growth and phosphorus (P) nutritional efficiency as affected by soil compaction and P rates. The treatments were composed of a 3 × 4 factorial scheme (soil bulk densities levels versus P fertilization rates) for two weathered tropical soils, a clayey Ferralsol (F_Clayey) and a sandy Ferralsol (F_Sandy). The soil bulk densities assessed were 0.90, 1.10 and 1.30 g cm^?3 for F_Clayey, and 1.35, 1.55 and 1.75 g cm^?3 for F_Sandy. The P rates were 0, 150, 300 and 600 mg kg^?1 for F_Clayey, and 0, 100, 200 and 400 mg kg^?1 for F_Sandy. Soil compaction reduced root growth, P content in the plant, P utilization efficiency and P recovery efficiency; and increased average root diameter. Phosphorus fertilization increased root length density, root surface area, dry matter, P content in the plant, P utilization efficiency and P uptake efficiency; and decreased P recovery efficiency. It was concluded that P fertilization is not effective to offset the deleterious effects of soil compaction on eucalypt growth and nutrition.

Abbreviations: F_Clayey: clayey Ferralsol; F_Sandy: sandy Ferralsol; R_Dens: root length density; R_Diam: root diameter; R_Surf: root surface area; R_DM: root dry matter; S_DM: shoot dry matter; WP_DM: whole-plant dry matter; R_P: root P content; S_P: shoot P content; WP_P: whole-plant P content; PU_tE: P utilization efficiency; PU_pE: P uptake efficiency; PRE: P recovery efficiency.     

Ryegrass yield and nutrient status after biochar application in two Mediterranean soils

This study was conducted to evaluate whether biochar, produced by pyrolysis at 300°C from rice husk and grape pomace (GP), affects plant growth, P uptake and nutrient status. A 3-month period of ryegrass (Lolium perenne L.) cultivation was studied on two Mediterranean agricultural soils. Treatments comprised control soils amended only with compost or biochar, and combinations of biochar plus compost, with the addition of all nutrients but P (FNoP) or without any fertilization at all (NoF). Application of both types of biochar or/with compost, in the presence of inorganic fertilization except P, significantly increased (P < 0.05) dry matter yield of ryegrass (58.9–77.6%), compared with control, in sandy loam soil, although no statistically significant increase was observed in loam soil. GP biochar and GP biochar plus compost amended loam soil harvests gave higher P uptake than control, in the presence of inorganic fertilization except P, whereas in sandy loam soil, a statistical increase was recorded only in the last harvest. In addition, Mn and Fe uptake increased with the addition of the amendments in both soils, while Ca increased only in the alkaline loam soil. Biochar addition could enhance ryegrass yield and P uptake, although inorganic fertilization along with soil condition should receive special attention.     

Response of Forage Chicory Seedlings to Available Soil Phosphorus in Two Soils in a Controlled Environment

Poor phosphorus (P) fertility is a problem limiting productivity on unimproved Appalachian soils and has been implicated in poor palatability of forage chicory (Cichorium intybus L.). Three cultivars were grown in a greenhouse at varying soil P levels in Gilpin and Hagerstown silt loam soils and harvested 48 and 77 days after planting. In Gilpin soil, available soil P (ASP) was positively associated with dry shoot mass, leaf mass, leaf area, and leaves per plant and negatively associated with specific leaf area. In Hagerstown soil, ASP was positively associated only with only dry shoot and leaf mass. At equivalent ASP levels, dry shoot and leaf mass, leaf area, and shoot concentrations of P, potassium, calcium, and magnesium were always greater in Hagerstown than Gilpin soil, whereas specific leaf area was less. Equalization of ASP concentration and environmental conditions did not eliminate growth-limiting differences between Gilpin and Hagerstown soils for chicory.     

Can liming reduce barium uptake by agricultural plants grown on sandy soil?

Uptake of barium (Ba) from soil by vascular plants varies among species. Despite the toxicity of soluble Ba compounds to plants, research on mechanisms controlling Ba uptake from natural soils is scarce. This study investigated the treatment effect of lime (CaCO₃) added to a sandy soil containing a total of 500 mg Ba kg^?1 on uptake and interspecies distribution of Ba in legumes and other cultivated food and feed plants. Nine species of grasses, vegetables, herbs, and legumes were cultivated under controlled conditions in a greenhouse experiment. The plants were harvested at maturity or flowering, dried, milled, and digested with nitric acid using the microwave technique prior to ICP‐MS analysis. All plant species acquired Ba from the soil in considerable amounts, probably due to low Ba adsorption potential of the sandy soil. Shoot tissue concentrations ranged from about 100 (grass) to 600 mg Ba kg^?1 (legume) and root concentrations from about 100 (tuber vegetable) to 700 mg kg^?1 (legume). Vicia cracca L. (bird vetch) showed an accumulation capacity due to high shoot concentrations of Ba compared to the other species. Higher yield accompanied by a potential dilution effect can partly explain why Trifolium repens L. (white clover), Pisum sativum ssp. arvénse L. (gray pea) and Hordeum vulgare L. (barley) did not display the highest Ba concentrations, but showed the highest Ba uptake from soil. High plant uptake of calcium (Ca) also seemed to enhance Ba uptake, by legumes in particular. However, liming reduced shoot Ba concentrations, particularly of species with low affinity for Ca. The risk of Ba accumulation thus raises toxicity concerns when forage legumes are cultivated in soils containing elevated concentrations of Ba.     

Minimizing ammonia volatilization from urea,improving lowland rice (cv. MR219) seed germination,plant growth variables,nutrient uptake,and nutrient recovery using clinoptilolite zeolite

The anionic nature and high cation exchange capacity (CEC) of clinoptilolite zeolite can be exploited to reduce ammonia (NH₃) loss from urea and to improve soil chemical properties to increase nutrient utilization efficiency in lowland rice cultivation. A closed-dynamic airflow system was used to determine NH₃ loss from treatments (20, 40, and 60 g clinoptilolite zeolite pot^?1). Seed germination study was conducted to evaluate the effects of clinoptilolite zeolite on rice seed germination. A pot study was conducted to determine the effects of clinoptilolite zeolite on rice plant growth variables, nutrient uptake, nutrient recovery, and soil chemical properties. Standard procedures were used to determine NH₃ loss, rice plant height, number of leaves, number of tillers, dry matter production, nutrient uptake, nutrient recovery, and soil chemical properties. Application of clinoptilolite zeolite (15%) increased shoot elongation of seedlings and significantly reduced NH₃ loss (up to 26% with 60 g zeolite pot^?1), and increased number of leaves, total dry matter, nutrient uptake, nutrient recovery, soil pH, CEC, and exchangeable Na⁺. Amending acid soils with clinoptilolite zeolite can significantly minimize NH₃ loss and improve rice plant growth variables, nutrient uptake, nutrient recovery, and soil chemical properties. These findings are being validated in our ongoing field trials.