Extraction of phosphorus,potassium, calcium,and magnesium from soils by an ion‐exchange resin procedure

Abstract

A procedure for the simultaneous extraction of phosphorus, potassium, calcium and magnesium from soils, by an ion‐exchange resin procedure applicable to large‐scale advisory soil testing, is described. The important steps are the disaggregation of soil by shaking in water during 15 minutes with a glass marble, the transference of the elements from the soil to a sodium bicarbonate treated mixture of anion and cation exchange resins during a 16‐hour shaking period, the separation of the resin from the soil by sieving and extraction of the elements from the resin.

The results of resin extractable calcium, magnesium and potassium were comparable to the results of these elements extracted with 1M NH₄OAc, to calcium and magnesium extracted with 1M KCl, and to potassium extracted with 0.025M H₂SO₄.

For phosphorus the resin extractable values were not comparable to the results obtained by the former routine method, based on the extraction with 0.025M H₂SO₄. The results of resin extractable P presented closer correlation with cotton response to phosphorus application in 28 field experiments (r = 0.85**) as compared with 0.025M H₂SO₄ extractable P (r = 0.68**), and also with P uptake by flooded rice in a pot experiment with eight lowland soil samples (r = 0.98**), as compared with extraction with 0.0125M H₂SO₄ in 0.050M HCl, for which the correlation was not significant. The reasons for the superiority of the extraction of P with the described procedure are discussed.     

Microsite assessment of forest soil nitrogen,phosphorus, and potassium supply rates in‐field using ion exchange membranes

Abstract

A new method for microsite assessment of soil nutrient supply in forest soil was developed. The method involves the use of ion exchange membranes to assess differences in soil nitrogen (N), phosphorus (P), and potassium (K) supply rates in‐field over small depth increments in the forest floor (i.e., the L, F, and H horizons). Ion exchange membranes were buried and retrieved from the forest floor in an aspen forest stand in Saskatchewan, Canada. Small (6 mm diameter) sections of the membrane were cut out and ion concentration on the sections measured to provide a nutrient supply rate at that location. Soil nutrient supply rates at the site ranged from 4.6–6.0, 7.3–8.5, 11.6–21.5, and 122–196μg 10 cm²#lb2 h^‐1 for NH₄ ⁺‐N, NC₃ ^‐‐N, P, and K, respectively. On average, the highly humified H horizon had the highest N and P supply rates, followed by the F horizon, with the surface litter (L horizon) having the lowest N supply rates. The simplicity and sensitivity of the procedure make this method appropriate for in‐field assessment of differences in soil nutrient supply over small vertical and horizontal distance and was especially appropriate for the forest floor horizons in forest soils.     

Gas exchange,water relations,and Ion concentrations of salt‐stressed tomato and melon plants

Abstract

Tomato and melon plants were grown in a greenhouse and irrigated with nutrient solution having an EC of 2 dS m^?1 (control treatment) and 4, 6, and 8 dS m^?1, produced by adding NaCl to the control nutrient solution. After 84 days, leaf water relations, gas exchange parameters, and ion concentrations, as well as plant growth, were measured. Melon plants showed a greater reduction in shoot weight and leaf area than tomato at the two highest salinity levels used (6 and 8 dS m^?1). Net photosynthesis (Pn) in melon plants tended to be lower than in tomato, for all saline treatments tested. Pn was reduced by 32% in melon plants grown in nutrient solution having an EC of 4 dS m^?1, relative to control plants, and no further decline occurred at higher EC levels. In tomato plants, the Pn decline occurred at EC of 6 dS m^?1, and no further reduction was detected at EC of 8 dS m^?1. The significant reductions in Pn corresponded to similar leaf Cl^? concentrations (around 409 mmol kg^?1 dry weight) in both plant species. Net Pn and stomatal conductance were linearly correlated in both tomato and melon plants, Pn being more sensitive to changes in stomatal conductance (g_s) in melon than in tomato leaves. The decline in the growth parameters caused by salinity in melon and tomato plants was influenced by other factors in addition to reduction in Pn rates. Melon leaves accumulated larger amounts of Cl^? than tomato, which caused a greater reduction in growth and a reduction in Pn at lower salinity levels than in tomato plants. These facts indicate that tomato is more salt‐tolerant than melon.     

Occurrence,sources, bioaccumulation,and air–water exchange fluxes of polycyclic aromatic hydrocarbons in Lake Hongze,China

Journal of Soils and Sediments - Compared with deep oligotrophic waters, the distribution and geochemical processes of polycyclic aromatic hydrocarbons (PAHs) in shallow eutrophic waters are more...     

Element absorption by sorghum root tips as influenced by multiple ion‐channel and ion‐pump inhibitors

Mineral nutrient absorption by 1‐cm root tips of Sorghum bicolor (L.) Moench. cv GP‐10, SC283, SC574, and/or Funk GS22DR from a 1‐hr exposure to Hoagland and Arnon complete mineral nutrient solution in the presence of diltiazem (0,10 mM), nifedipine (0,10 mM), or SITS (0, 1 mM) was evaluated using inductively coupled plasma emission photometry (ICP). Calcium (Ca²⁺) ‐ channel blockers (i.e. ‐ diltiazem, nifedipine, and verapamil) and PCMBS induced significantly decreased quantities of Ca²⁺ in root tips but the anion channel blocker, SITS, did not induce any response in Ca²⁺ uptake. Responses of phosphorus (P), zinc (Zn), boron (B), manganese (Mn), iron (Fe), magnesium (Mg), and copper (Cu) to all of the ion uptake modifiers were highly variable between the cultivars with increased, decreased, or no influence on ion uptake. As yet unrecognized multiple mechanisms of ion uptake through the root plasma membrane are necessary to explain the date.     

Effect of ammonium sulfate,ammonium chloride and root‐zone acidity on inorganic ion content of tobacco

Tobacco plants (Nicotiana tabacum L. cv NC82) were supplied with (NH₄)₂SO₄, or NH₄Cl at root‐zone pH of 6.0 and 4.5 in hydroponic culture for 28 days. Dry matter accumulation, total N and C content, and leaf area and number were not affected by the NH₄ ⁺ source or root‐zone pH. Plants supplied with NH₄C1 accumulated up to 1.2 mM Cl g DW^‐1, but accumulated 37% less inorganic H₂PO₄ ^‐ and 47% less SO₄ ^2‐ than plants supplied with (NH)₂SO₄. The large Cl^‐ accumulation resulted in NH₄C1 –supplied plants having a 31% higher inorganic anion (NO₃ ^‐, H₂, PO₄ ^‐, SO₄ ^2‐, and Cl^‐) charge. This higher inorganic anion charge in the NH₄C1‐supplied plants was balanced by a similar increase in K⁺ charge. Plants supplied with NH₄Cl accumulated greater concentrations of Cl^‐ in leaves (up to 5.1% of DW) than plants supplied with (NH₄)₂SO₄ (less than ‐% DW). Despite the high Cl^‐ concentration of leaves in NH₄Cl supplied plants, these plants showed no symptoms of Cl^‐ toxicity. This demonstrates that toxicity symptoms are not due solely to an interaction between high Cl^‐ concentration in tissue and NH₄ ⁺ nutrition. The increase in root‐zone acidity to pH 4.5 from 6.0 did not induce toxicity symptoms.     

Response of Hibiscus Rosa‐Sinensis L. to varying levels of potassium fertilization: Growth,gas exchange and mineral element concentration

Little is known about the effect of varying levels of potassium (K) on the mineral element concentration, growth, and gas exchange, characteristics of woody ornamental plants. The commercially important woody ornamental species Hibiscus rosa‐sinensis L. cv. Leprechaun was evaluated for K response in a series of three experiments with full strength Hoagland's nutrient solution, which supplied 0 to 10 mM K. Plants grown with 4 mM K in nutrient solution (2.4% leaf tissue K) had the greatest shoot growth and root extension. Gas exchange rates (net photosynthesis, transpiration, and stomatal conductance) were also highest at 4 mM K compared to the control (0 mM K /0.6% leaf tissue K), 0.2, 2.0 and 10 mM K treatments. The application of 4 mM K increased net photosynthesis and tranpiration by 2.1 fold and stomatal conductance by 4.5 fold over 0 mM K controls. Increasing K in nutrient solution correlated positively with tissue K, manganese (Mn), and zinc (Zn), but negatively with nitrogen (N), phosphorus (P), calcium (Ca), and magnesium (Mg). There was a stronger sink for K in yonger leaves (the first to fourth fully expanded leaf from the shoot apex) which had higher K concentration than older leaves (the eighth to twelfth fully expanded leaf from the shoot apex). However, with increasing K in nutrient solution, K concentration in leaf tissue increased regardless of leaf age, and the difference between the younger and older leaf was constant. Daily application of 10 mM K resulted in 6.9% leaf tissue K and caused a decrease in plant total dry matter, net photosynthesis, compared to 4 mM K treated plants. However, these parameters remained higher in 10 mM K plants, which retained high ornamental quality than in 0 mM controls. Plants fertilized with 10 mM K, had the highest leaf tissue K and Zn, but lowest P, Ca, Mg, iron (Fe), copper (Cu) and boron (B). Nevertheless, the 10 mM K treated plants exhibited no morphological differences or deficiency symptoms; rather those plants had similar vegetative vigor and flower bud formation rate as those at 4 mM K.     

Acid‐soil‐stress influence on mineral‐ion contents of sorghum leaves and juvenile panicles

Sorghum [Sorghum bicolor (L.) Moench cv RTX430, SC214, SC574, SC599, TAM428, and SC326xSC103] were grown on soils of pH 4.2 or 6.2–6.5. Leaf and nonexserted juvenile panicle tissues were collected at 75 days after planting. Fresh and dry weights were measured and element contents [sulfur (S), phosphorus (P), magnesium (Mg), calcium (Ca), potassium (K), zinc (Zn), iron (Fe), and copper (Cu)] were measured by atomic absorption. Significant cultivar differences in ion concentration (μmol/g dry weight) were found. Juvenile panicles had higher ion concentration (μmol/g dry weight) [S, P, Mg, Ca, K, Zn, and Cu) than leaves. Within leaf tissue, ion concentration (μmol/g dry weight) was correlated with tissue water content (g water/g dry weight).     

Population viability analysis of European bison populations in Polish and Belarusian parts of Bia?owie?a Forest with and without gene exchange

European bison (Bison bonasus) became extinct in the wild at the beginning of the 20th century. The contemporary Lowland line of bison was founded by seven individuals that survived in captivity. The largest population of Lowland bison live in the Bia?owie?a Forest, but the forest and the population are divided by a border fence between Poland and Belarus. This fence is a barrier to the movement of ungulates. In this study, we used population genetic models to predict the future viability of the Polish and Belarusian bison populations. We determined the founder contribution, founder equivalent, mean inbreeding coefficient, mean kinship, and the proportion of genetic diversity retained in the Belarusian bison population. Although the founding group of the Belarusian population was larger than that of the Polish population, the latter had more favourable genetic parameters. We assessed inbreeding depression for fecundity in free-ranging European bison compared to captive individuals. Using population viability analysis (PVA) we modelled both bison populations with or without gene exchange, and with or without incorporating the kinship of the founders. When founder kinship was included, in both populations the mean number of alleles and the gene diversity retained within extant populations decreased substantially compared to PVA models in which founders were not related. The worst genetic parameters were obtained for the Belarusian population under a scenario in which the founders are related and gene exchange is lacking, which is the closest to the real situation. Creation of passages for animals by partial removal of the border fence would have a favourable effect on the genetic variation and viability of both bison populations, especially the Belarusian.     

Rotenone and rotenoids in cubè resins, formulations, and residues on olives

Rotenone and rotenoids (deguelin, beta-rotenolone (12a beta-hydroxyrotenone), tephrosin (12a beta-hydroxydeguelin), 12a alpha-hydroxyrotenone, and dehydrorotenone) were determined in cubè resins and formulations. Cubè resins from Lonchocarpus contain large quantities of deguelin (ca. 21.2%) and smaller quantities of tephrosin (ca. 3.5%) and beta-rotenolone (ca. 3.0%). The composition of commercial formulations may present very different rotenoid contents depending on the extracts used to prepare them. Because these rotenoids also present insecticide activity, the efficacy of these formulations may be very different. The storage stability and photodegradation of some rotenone formulations were studied. Rotenone and rotenoids are very sensitive to solar radiation, which degrades them rapidly, with half-lives in the order of a few tens of minutes. Some formulations show greater disappearance rates than that of cubè resin, indicating that not much attention has been paid to protecting the active ingredients from photodegradation in the formulation. A study on the residues on olives was also carried out to assess not only the rotenone content, but also that of the main rotenoids. At harvest, the residues of deguelin, tephrosin, and beta-rotenolone were 0.10, 0.06, and 0.10 mg/kg, respectively, very similar to rotenone (0.08 mg/kg), and though a few data indicate similar acute toxicity values for deguelin, only rotenone is taken into consideration in the legal determination of the residue.     

Soil–atmosphere greenhouse gas exchange in a cool,temperate Eucalyptus delegatensis forest in south-eastern Australia

Forests are the largest C sink (vegetation and soil) in the terrestrial biosphere and may additionally provide an important soil methane (CH₄) sink, whilst producing little nitrous oxide (N₂O) when nutrients are tightly cycled. In this study, we determine the magnitude and spatial variation of soil–atmosphere N₂O, CH₄ and CO₂ exchange in a Eucalyptus delegatensis forest in New South Wales, Australia, and investigate how the magnitude of the fluxes depends on the presence of N₂-fixing tree species (Acacia dealbata), the proximity of creeks, and changing environmental conditions. Soil trace gas exchange was measured along replicated transects and in forest plots with and without presence of A. dealbata using static manual chambers and an automated trace gas measurement system for 2 weeks next to an eddy covariance tower measuring net ecosystem CO₂ exchange. CH₄ was taken up by the forest soil (?51.8 μg CH₄-C m^?2 h^?1) and was significantly correlated with relative saturation (S_r) of the soil. The soil within creek lines was a net CH₄ source (up to 33.5 μg CH₄-C m^?2 h^?1), whereas the wider forest soil was a CH₄ sink regardless of distance from the creek line. Soil N₂O emissions were small (<3.3 μg N₂O-N m^?2 h^?1) throughout the 2-week period, despite major rain and snowfall. Soil N₂O emissions only correlated with soil and air temperature. The presence of A. dealbata in the understorey had no influence on the magnitude of CH₄ uptake, N₂O emission or soil N parameters. N₂O production increased with increasing soil moisture (up to 50% S_r) in laboratory incubations and gross nitrification was negative or negligible as measured through ¹⁵N isotope pool dilution.The small N₂O emissions are probably due to the limited capacity for nitrification in this late successional forest soil with C:N ratios >20. Soil–atmosphere exchange of CO₂ was several orders of magnitude greater (88.8 mg CO₂-C m^?2 h^?1) than CH₄ and N₂O, and represented 43% of total ecosystem respiration. The forest was a net greenhouse gas sink (126.22 kg CO₂-equivalents ha^?1 d^?1) during the 2-week measurement period, of which soil CH₄ uptake contributed only 0.3% and N₂O emissions offset only 0.3%.     

Potassium→ammonium exchange of two benchmark soils from Botswana and its implication for nitrogen economy of the soils

Ion exchange preferences for NH₄⁺ and K⁺ by soil exchanger surface can greatly affect the NO₃^? leaching into groundwater and nitrogen-use efficiency in agricultural production. Since NH₄⁺ and K⁺ salts are usually applied together as fertilizers, the binary K→NH₄ exchange of two benchmark Botswana soils, Pellustert and a Haplustalf, was studied to determine the selectivity coefficients and the thermodynamic exchange constant with special reference to N economy. The Vanselow and the Gaines and Thomas coefficients indicated preference for NH₄⁺ by the Pellustert and K by the Haplustalf across the exchanger phase composition. The equilibrium constant (K_ex) was 1.807 for the Pellustert and 0.174 for the Haplustalf. The exchange free energy (ΔG_ex⁰) was ?1.467 kJ mol^?1 for the Pellustert and 4.334 kJ mol^?1 for the Haplustalf. Negative ΔG_ex⁰ for the Pellustert is consistent with preference for NH₄⁺ to K⁺ in contrast to positive ΔG_ex⁰ for the Haplustalf. The greater stability of NH₄X than KX complex in the Pellustert, and KX than NH₄X in the Haplustalf, would mean increased residence time of NH₄⁺ in the Pellustert than the Haplustalf. The implication of short residence time of NH₄⁺ in soil is rapid nitrification, thereby leading to NO₃^??N leaching losses and possible groundwater contamination.     

Land use effects on microbial biomass C, β-glucosidase and β-glucosaminidase activities,and availability,storage, and age of organic C in soil

Microbial biomass, β-glucosidase and β-glucosaminidase activities, and availability, storage, and age of soil organic C were investigated after 26 years of conversion from sugarcane (Saccharum officinarum) to forest (Eucaliptus robusta or Leucaena leucocephala), pasture (mixture of tropical grasses), and to vegetable cropping (agriculture) in a vertisol in Puerto Rico. Soil organic C (SOC) at 0–100 cm was similar under Leucaena (22.8 kg C/m²), Eucalyptus (18.6 kg C/m²), and pasture (17.2 kg C/m²), which were higher than under agriculture (13.0 kg C/m²). Soil organic N (SON) at 0–100 cm was similar under the land uses evaluated which ranged from 1.70 (under agriculture) to 2.28 kg N/m² (under Leucaena forest). Microbial biomass C (MBC) and N (MBN) of the 0–15-cm soil layer could be ranked as: pasture > Leucaena = Eucalyptus > agriculture. The percentages of SOC and SON present as MBC and MBN, respectively, were nearly 1% in pasture and less than 0.50% in forest under Leucaena or Eucalyptus and agricultural soil. The activity of β-glucosidase of the 0–15-cm soil layer could be ranked as: Leucaena = Eucalyptus > pasture > agriculture; while β-glucosaminidase activity was ranked as: Eucalyptus > Leucaena = pasture > agriculture. The soil δ ¹³C changed from 1996 to 2006 in forest under Eucalyptus (18.7‰ to 21.2‰), but not under Leucaena (20.7‰ to 20.8‰). The soil under Leucaena preserved a greater proportion of old C compared to the forest under Eucalyptus; the former had an increased soil mineralizable C from the current vegetation inputs. The soil under agriculture had the lowest enzyme activities associated with C cycling, lowest percentage of SOC as MBC, highest percentage of SOC present as mineralizable C, and highest percentage of MBC present as mineralizable C compared to the other land uses.     

Pharmacological, structural, and drug delivery properties and applications of 1,3-β-glucans

1,3-β-Glucans are a class of natural polysaccharides with unique pharmacological properties and the ability to form single- and triple-helical structures that can be formed into resilient gels with the application of heat and humidity. The pharmacological capabilities of 1,3-β-glucans include the impartation of tumor inhibition, resistance to infectious disease, and improvements in wound healing. Curdlan is a linear 1,3-β-glucan that has been used extensively to study the nature of these helical structures and gels, and Curdlan sulfates have found ongoing application in the inhibition of HIV infection. 1,3-β-Glucan gels have been used in food science as stabilizers and encapsulating agents, in nanoscience as scaffolds to build nanofibers and nanowires, and in drug delivery to form nanoparticles and create helical micelles encapsulating polynucleotides. 1,3-β-Glucans are beginning to have enormous significance due to their dual nature as structure-forming agents and pharmacological substances, and research is especially focused on the application of these polymers in animal nutrition and drug delivery.     

Effect of wetting and drying on DTPA‐extractable Fe,Zn, Mn,and Cu in soils

Abstract

The study reported herein was intended to determine the effect of (i) wet‐incubation and subsequent air‐drying, and (ii) oven‐drying on DTPA‐Fe, Zn, Mn, and Cu.

Analysis of wet‐incubated soils showed significant decreases in DTPA‐Fe, Mn, and Cu at the 1% and Zn at the 10% level of probability. Air‐drying of these moist‐incubated soils increased the levels of Fe, Zn, and Cu to values close to their original levels. Levels of Mn sharply deviated from their original values after air‐drying of incubated soils. Correlation coefficients (r) between the amounts of extractable nutrients in original air‐dry soils and wet‐incubated soils were 0.54, 0.87, 0.91, and 0.13 for Fe, Zn, Cu, and Mn, respectively. Oven‐drying increased the levels of DTPA‐extractable micronutrients from 2 to 6 fold.     

Nitrogen,phosphorus, and potassium effects on pre‐ and post‐transplant growth of salvia and vinca seedlings

Pre‐ and post‐transplant growth of bedding plants is affected by seedling nutrition. However, there is little information available on how seedling nutrition affects the growth of ornamental bedding plants. In this study, we quantified the effects of nitrogen (N) (8 to 32 mM) and phosphorus (P) and potassium (K) concentration (0.25 to 1 mM) of the seedling fertilizer on pre‐ and post‐transplant growth and nutrient element content of salvia (Salvia splendens F. Sellow ex Roem. & Schult.) and vinca (Catharanthus roseus L.) seedlings. Shoot growth of salvia and vinca increased with increasing concentrations of N in the pre‐transplant fertilizer and these differences lasted until the end of the study at 15 days after transplanting. Pre‐transplant root dry mass of these species was not affected by the N concentration of the fertilizer, but root dry mass at 12 days after transplanting was positively correlated with the N concentration of the pre‐transplant fertilizer. Increasing N concentrations in the seedling fertilizer increased tissue N levels of salvia and decreased tissue K level of vinca at transplanting. Increasing P and K concentrations in the pre‐transplant fertilizer increased tissue P level of salvia and P and K levels of vinca, but had little effect on seedling growth. Leaf area and root dry mass at transplanting decreased slightly with increasing P and K concentration in the fertilizer. There were no lasting effects of pre‐transplant P and K concentration of the fertilizer. These results indicate that salvia and vinca seedlings can benefit from high concentrations of N (up to 32 mM) in the fertilizer, while only low concentrations of P and K (0.25 mM) are needed.     

Enhancement of nitrate efflux and the plasma membrane hydrogen ion‐transport activity of barley roots by nitrate treatment

The effect of nitrate (NO₃) on the activities of hydrogen (H⁺)‐ATPase and H⁺‐transport in the plasma membrane vesicles isolated from barley (Hordeum vulgare L. cv. Kikaihadaka) roots was investigated. After treatment with 10 mM NO₃ for longer than 24 h, both activities of H⁺‐ATPase and H⁺‐transport assayed in the presence of chloride (Cl) were stimulated less than 20%. While H⁺‐transport activity was approximately two times higher in NO₃‐grown roots than in control roots when assayed in the presence of NO₃ instead of Cl. This result suggests that NO₃ is permeable in the plasma membrane vesicles isolated from NO₃‐grown roots rather than that of the control, and thereby stimulate H⁺‐transport activity through the collapse of positive potentials established by H⁺‐ATPase. Furthermore, NO₃ efflux from roots was markedly enhanced after 48 h of the exposure to NO₃. Taken together, NO₃ efflux may be mediated by the permeability to NO₃ which is induced by NO₃.     

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.     

Comparison of broiler litter and inorganic nitrogen,phosphorus, and potassium for double‐cropped sweet corn and broccoli

Two rates of broiler litter (20 and 40 mt/ha) were compared to recommended rates of inorganic nitrogen (N), phosphorus (P), and potassium (K) in a double cropping system of spring sweet corn (Zea mays L. ‘Silverqueen') and fall broccoli (Brassica oleracea L, ‘Southern Comet')‐ Sweet corn matured one week earlier both years when fertilized with 40 mt/ha of broiler litter compared to commercial fertilizer. The early maturity may be due to improved P nutrition. Similar or higher yields of fall broccoli were produced with broiler litter following sweet corn than with commercial fertilizer.     

The determination of ammonium and chloride by an auto‐analyser for the measurement of cation exchange capacity of soils

Abstract

An auto‐analyser method has been developed for the simultaneous determination of NH₄ ⁺ and Cl^‐ in Ca(NO₃)₂/KNO₃ extracts of NH₄Cl treated soils for cation exchange capacity measurements. The method gives satisfactory agreement with manual titration procedures.