Effect of seed‐placed fertilizer on the emergence (germination) of soybeans (Glycine max L.) and snapbeans (Phaseolus vulgaris L.)

Abstract

Field trials were established on a loamy fine sand and a silt loam using snapbeans and soybeans as test crops, respectively. Row fertilizer was placed with the seed (seed‐placed). Treatments were arranged in a 3×3×3 factorial experiment, and N, P, and K were applied in all combinations at three rates (0, 3.4, and 6.8 kg/ha). Ammonium nitrate (AN), monoammonium phosphate (MAP), concentrated superphosphate (CSP) and potassium chloride (KCl) were used as sources of N, P and K. Additional treatments compared MAP with diammonium phosphate (DAP) and KCl with potassium nitrate (KNO₃).

The salt index of each treatment was inversely related to emergence, i.e. as the salt index increased, the emergence decreased. Level of N was more important than level of P or K in regards to reduction in emergence. Snapbeans grown on a loamy fine sand were extremely sensitive to damage from seed‐placed fertilizer, even at rates as low as 3.4 kg/ha of N, P or K. Soybeans planted on a silt loam soil were less sensitive than snapbeans planted on a loamy sand. The soybeans were able to tolerate up to 10.2 kg/ha of seed‐placed P plus K or 6.8 kg/ha of seed‐placed N plus P or N plus K without causing a significant delay in emergence.     

Effects of soil ph,nitrogen source,phosphorus, and molybdenum on early growth and mineral nutrition of burley tobacco

Abstract

Previous research has indicated that P application may influence plant Mo nutrition, and that both P and Mo are influenced by soil pH. This is of interest, since Mo is deficient in some soils and because large quantities of acidifying nitrogenous fertilizers are commonly applied in production of burley tobacco (Nicotiana tabacum L.).

Burley tobacco was grown in two experiments using Maury silt loam soil (Typic Paleudalfs) to determine the influence of soil acidity, form of N applied, and P application on plant growth and mineral nutrition. The studies were conducted in the greenhouse so that high root densities would develop and the data primarily reflect rhizosphere effects.

Ammonium application depressed rhizosphere pH 0.4 to 0.6 pH units. Nitrate nutrition raised soil pH less than 0.1 pH unit. Plants supplied NH₄ exhibited slower early growth than plants supplied NO₃. Several significant interactions involving soil pH, N source, P, and Mo occurred. In the first experiment, plant P was not affected by form of N applied, while in the second experiment NH₄ application resulted in higher plant P concentration, both in presence and absence of applied P. Application of NH₄ also increased plant weight in the second experiment. Plant P concentration was influenced by pH, being greatest at pH 6.2 and decreasing as pH levels decreased or increased. Plant Mo concentration did not differ among forms of N at pH 5.4, but at pH 7.2 was three times greater in the presence of NO₃. When Mo was applied, P addition enhanced plant Mo concentration, but when Mo was not applied, P addition did not increase Mo concentration. This effect of P on Mo occurred only in the presence of N and was greater in the presence of NH₄ than NO₃. These observations suggest that enhancement of plant Mo nutrition by P application may be dependent on adequate levels of N being present.     

Chlorine concentrations in alfalfa herbage and soil with KCl topdressing of a low fertility silt loam soil

Abstract

The purpose of this study was to determine the amount of Cl in plants and soil following topdressing of alfalfa with increasing amounts of KCl (0–0–60). The study was conducted with Ranger alfalfa on a low K Piano silt loam soil that had been topdressed twice during three years with a total of zero, 203, 406, 1220, and 2034 kg/ha of Cl as KCl (0, 224, 448, 1334, and 2240 kg/ha of K). Herbage was harvested annually three times at first flower plus an early October cut (4 cuts). The 3‐year average herbage yields were highest with 1220 kg/ha of topdressed Cl. Herbage yields decreased with 2034 kg/ha of Cl, but not significantly below that at 1220 kg/ha. Weakened and yellowed plants were noted in the spring of the second harvest year after 2034 kg/ha of Cl had been applied, and the first‐flower herbage contained 1.90% Cl. It was concluded that the weakened condition of the alfalfa was due to excess Cl.

Movement of Cl through the silt loam soil was rapid. The largest concentrations of Cl in the soil two years after the last KCl application were at the 76 to 91‐cm soil depth, the deepest soil sample tested.     

Influence of soil pH and molybdenum fertilization on the productivity of Maryland tobacco. I. Field investigations

Abstract

To gain information on soil factors which may limit productivity of tobacco on Coastal Plain soils in Maryland, studies were conducted on Monmouth sandy loam soils in 1982 to 1984 and in 1988. The 1982–1984 study involved the application of dolomitic lime in 1982 at rates of 0, 3.6, 7.3, and 14.6 M ton/ha which achieved pH values of 4.4, 4.7, 5.0, and 5.3, respectively, in combination with annual applications of supplemental molybdenum (Mo) at rates equal to 0, 0.28, 0.55, and 1.1 kg/ha. The 1988 study involved lime application rates of 6.0, 17.0, and 25.0 M ton/ha to achieve pH values of 5.0, 5.6, and 6.0, respectively, in combination with Mo rates equal to 0, 0.5, and 1.0 k/gha. Studies were also conducted in 1988 involving the application of 0, 0.55, and 1.10 kg/ha supplemental Mo without lime additions to two sites having pH values of 5.0 and 5.5, respectively. Cured leaf yields, total nitrogen (N) and alkaloid levels were measured in all studies. Leaf Mo levels were monitored in the 1988 studies. Applications of 14.6 M ton/ha of lime in 1982 induced significant yield increases which averaged 13.8% over controls in the 3‐year study. No significant benefits from supplemental Mo were found at the 0 and 3.6 M ton/ha lime treatments (< pH 4.7) in the 1982–84 study or in any of the 1988 studies. However, 1.1 kg/ha Mo applied in combination with 7.3 and 14.6 M ton kg/ha lime increased yields by 16 to 22% above the control treatments in the 1982–84 study, and by 17.8% and 18.7% when applied in combination with 6.0 and 25.0 M ton/ha, respectively, in 1988. In 1988, leaf Mo increased with increased Mo rates, especially at higher pH values. Treatment effects on total N and alkaloid levels were non‐significant in most instances suggesting that N metabolism activities in the control plants were not being limited by plant available Mo (0.10 μg/g) in the soil.     

Is mechanical soil aeration a strategy to alleviate soil compaction and decrease phosphorus and suspended sediment losses from irrigated and rain‐fed cattle‐grazed pastures?

Agriculture is a major source of phosphorus (P) and suspended sediment (SS) losses to aquatic ecosystems promoting eutrophication. Mechanical soil loosening equipments such as topsoil looseners or aerators have been reported to improve the physical quality and infiltration of soils susceptible to livestock damage resulting from treading. We hypothesized that soil aeration would significantly decrease the volume of surface runoff and consequent losses of P and SS compared with non‐aerated soil (control) in cattle‐grazed pasture on a poorly structured silt‐loam soil. Hydrologically isolated plots (2 m long × 1 m wide × 0.15 m deep) were installed in aerated and control plots to collect surface runoff following irrigation or rainfall and analysed for P and SS losses for 1 year. Soil physical properties [% macroporosity, bulk density, saturated hydraulic conductivity (K_sat) and unsaturated hydraulic conductivity (K_unsat at ?1kPa)] were measured in the aerated and control treatments and taken before each irrigation event (n = 12). Six months after mechanical aeration was employed, but before cattle grazing commenced, no significant differences in soil physical quality were found between aerated and control treatments, with the exception of a minor increase in K_unsat for the control plots. This lack of treatment difference continued after grazing and was largely attributed to the re‐settling of the poorly structured and dispersive soil. Flow‐weighted mean concentrations and annual loads of dissolved reactive P (DRP) on the mechanically aerated soil (2.24 kg DRP/ha) were approximately double those from the control treatment (1.20 kg DRP/ha). However, no significant differences were observed between treatments for surface runoff volumes and losses of total P and total SS, which may reflect the similar soil physical conditions exhibited between treatments throughout most of the trial. As observed elsewhere, time (days) since grazing or fertilizer application was found to influence P and/or SS losses. We conclude that aeration did not decrease P and SS losses. Any changes in soil physical properties such as macroporosity were short‐lived and therefore unlikely to influence surface runoff and subsequent P and SS losses for this soil type.     

Influence of Sulfur Fertility on Wheat Yield Performance on Alluvial and Upland Soils

Abstract: In recent years, sulfur (S) deficiencies in winter wheat (Triticum aestivum L.) have become more common, particularly on coarse‐textured soils. In Study I, field experiments were conducted in 2001/2002 through 2003/2004 on Mississippi River alluvial soils (Experiment I) and an upland, loessial silt loam (Experiment II) to evaluate the influence of spring S rates of 0, 5.6, 11.2, and 22.4 kg ha^?1 and a fall rate of 22.4 kg sulfate (SO₄)‐S ha^?1 on grain yield of three varieties. In Study II, field experiments were conducted in 2001/2002 and 2004/2005 on alluvial soils to evaluate the influence of spring S rates of 0, 5.6, 11.2, and 22.4 kg SO₄‐S ha^?1 in fields where S‐deficiency symptoms were present. Grain yield response to applied S occurred only on alluvial, coarse‐textured, very fine sandy loam soils (Study II) that had soil SO₄‐S levels less than the critical level of 8 mg kg^?1 and organic‐matter contents less than 1 g kg^?1 in the 0‐ to 15‐, 15‐ to 30‐, and 30‐ to 45‐cm depths. Soil pH increased with soil depth. Optimum S rate was 11.2 kg SO₄‐S ha^?1 in 2001/2002 and 5.6 kg SO₄‐S ha^?1 in 2004/2005. On the upland, loessial silt loam soil, soil SO₄‐S levels accumulated with depth, whereas organic‐matter content and pH decreased. In the loessial soils, average soil SO₄‐S levels in the 15‐ to 30‐ and 30‐ to 45‐cm soil depths were 370% greater than SO₄‐S in the surface horizon (0 to 15 cm).     

Soybean response to carbon dioxide and molybdenum

Abstract

The objective of this experiment was to measure the impact of molybdenum (Mo) addition to the soil on changes in rate of photosynthesis (PN), specific root nodule nitrogenase activity (SNA), chlorophyll ‐ (Chl‐a) and (Chl‐b) and biomass of soybean (Glycine max L. Merrill), exposed to carbon dioxide (CO₂) (350, 400, or 450 μL/L) for 5 d during its sensitive growth stage (R2). Plants grown in soil with Mo (0, 0.5, or 1.0 mg/kg soil dry weight) were exposed to carbon dioxide (CO₂) in open‐top field chambers for 12 h/d for 5 d with a nitrogen (N)‐free fertilizer. Increasing CO₂ levels reduced SNA and increased both Chl‐a and Chl‐b. Addition of 1 mg/kg Mo significantiy reduced SNA for plants grown with 350 μL/L CO₂ with no change in PN.     

Influence of ammonia fertilization on cotton production in conservation tillage systems

Abstract

Field studies were conducted to determine the influence of ammonia fertilization on cotton grown in conservation tillage systems. The studies were located on a Decatur silt loam (Rhodic Paleudult) in the Limestone Valley and a Norfolk sandy loam (Typic Paleudult) in the Coastal Plain of Alabama. Winter annual legumes, crimson clover (Trifolium incarnatum L. at the Norfolk site) and hairy vetch (Vicia villosa Roth at the Decatur site) were established as whole plots along with a winter fallow area. Sources of fertilizer differing widely in their NH₄+‐N contents were used for split plot treatments applied at time of cotton (Gossypium hirsutum L.) planting. Fertilizer treatments included calcium nitrate, ammonium nitrate, urea, urea with dicyandiamide, and a no N check. The cotton was planted with a strip‐till conservation planter. Nitrogen production by winter legumes was adequate to meet N requirements for cotton on the Decatur silt loam (67 kg N/ha) but not at the Norfolk sandy loam site (101 kg N/ha). Cotton populations were 24% higher in fallow than legume whole plots. Differences in plant growth and N concentrations were highly variable and treatment trends were not found. Seed cotton yields were 4% higher in fallow than legume plots. Maximum populations and yields were achieved with ammonium nitrate in fallow area and urea in legume areas.     

Response of burley tobacco to banded fertilizer and in‐row subsoiling

Abstract

Field experiments were conducted during 4 years at two locations in Kentucky to study the response of burley tobacco to phosphorus (P) and potassium (K) fertilizer rate and placement, and to in‐row subsoiling. In one experiment on Pope soil (mesic Fluventic Dystrochrepts), dry matter and P and K uptake 40 days after transplanting, and cured leaf yield and value/ha were increased as application of a 5–13–36 (%N‐P₂O₅‐K₂O) grade fertilizer increased from 310 to 930 kg/ha. Generally, fertilizer placed in 40‐cm wide bands directly under and parallel to the row was more effective than broadcasting and in‐row subsoiling was more effective than not subsoiling. Significant 2‐way and 3‐way interactions suggested that plant responses to band applications over broadcasting were greater in the presence than absence of subsoiling. In another experiment conducted on two silt loam soils, Pope and Maury (typic Paleudalfs), fertilizer applied in a 40‐cm band with in‐row subsoiling was more effective than broadcasting without subsoiling or placement in 10‐cm wide bands applied 0.6‐m apart and perpendicular to the row without subsoiling. Growth and yields increased up to the 620 kg/ha rate and 40 days after transplanting, soil pH decreased and soil electrical conductivity and plant manganese (Mn) increased with increased rate of fertilizer.     

Preliminary studies on triticale,wheat, barley,and rye responses to lime and N.

Abstract

The lime and N requirements for triticale (X Triticosecale Wittmack) have not been established because of the relatively short history of the crop. This study was designed to evaluate the effects of lime and high N rates on triticale, wheat (Triticum aestivum L.), barley (Hordeum vulgare L.), and rye (Secale cereale L.) on Dickson silt loam (Typic Paleudult) and Decatur silty clay loam (Rhodic Paleudult) in 1974–1976. The soils had pH values of 4.9 and 5.5 with no lime and 5.4 and 5.8, respectively, when limed as recommended. The fertilizer rates were 112, 140, and 170 kg N/ha. Yields and N, P, K, Ca, Mg, Mn, Fe, Al, Zn, Cu, and B were determined in straw and grain. Liming the Dickson soil increased the straw yields of barley at 112 kg N/ha and grain yields of the cultivars generally at the 170 kg N/ha rate. Liming the Decatur soil did not have consistent effects on straw yields but increased the grain yields of the wheat and rye cultivars. Increasing N rate increased the straw yields of wheat on Dickson but decreased the grain yields of barley in the same soil with no lime. Nitrogen fertilization did not have consistent effects on the Decatur soil. The N, P, K, Ca, Mg, and Mn compositions suggested that more differences occured at the species level than at the cultivar level.     

Heavy metal and volatile organic chemical removal and treatment in on-site wastewater systems

In Wisconsin, motor vehicle waste fluids (MVWF) enter catch basins along with rinse waters and are discharged to drainfields (soil absorption systems) after mixing with domestic wastewater in a septic tank (systems installed prior to 1992). The purpose of this study was to determine if removal/treatment of heavy metals and volatile organic chemicals (VOCs) found in spent oils, greases, and solvents occurs in drainfields that receive MVWFs. Soil samples were collected beneath and soil gas samples were collected above three gravel beds in drainfields installed in loamy sand or silt loam soils. Cadmium, chromium, and lead concentrations in soil 15 cm and greater beneath beds in loamy sand and silt loam soils were similar to background concentrations. Heavy metals in drainfields would most likely be found in the clogging layer at the infiltrative surface of gravel and soil. The VOCs 1,3,5-trimethylbenzene and m- and p-xylenes were found beneath beds in loamy sand soils; concentrations of detected VOCs ranged from 20–270 mg kg^?1. Volatile organic chemicals were not detected beneath the bed in silt loam soils. Drainfields in loamy sand soil appear to provide less treatment of VOCs compared to drainfields in silt loam soils. Volatile organic chemicals were found in soil gas above drainfields in both soil types. Thus, some VOCs diffuse from the drainfield to the soil surface.     

Nitrogen management for malting barley

Abstract

Malting barley is a specialized agricultural crop in which high yields and quality are production objectives. We evaluated the effects of different N rates on barley yields and selected malting quality parameters grown on irrigated silt loam soils (Xerollic calciorthids). Maximum barley yields having acceptable malting quality parameters were obtained when the preplant soil NO₃‐N plus fertilizer N was between 100 to 120 kg N/ha. About 33 kg N/ha was taken up by the plants from the mineralization of soil organic N. Higher available N levels decreased malting quality parameters below acceptable levels. Germination percentage was not changed by the different N rates.     

Vegetative responses of silage cats fertilized in the growth chamber with various levels of N and K

Oats (Avena sativa L.) are often harvested for silage in the Great Lakes states. The objective of this research was to obtain additional information on the response of oats to N and K fertilization. ‘Froker’ spring oats were grown from seed under 27 C day/21 C night temperatures in a growth chamber. The soil was a 4:1 mixture of Dodge silt loam soil (Typic Argiudoll) and sand that contained low levels of N and K. The potted plants were fertilized with 0, 50, 100, and 200 kg/ha of N as NH₄NO₃ in all combinations with 0, 200, and 400 kg/ha of K as KC1. Plants were harvested at early inflorescence emergence (43 days after seeding). Fertilization with N significantly increased the dry matter yields (g/pot) of the herbage and total plant, the number of axillary tillers/pot, and herbage N percentage. Root yields were increased only with the first increment of N. Nitrogen fertilization had no significant effect on height of the primary shoots and herbage K percentage. The first increment of K (200 kg K/ha) significantly increased herbage and total plant dry matter yields, while the second increment (400 kg K/ha) gave no further yield increases. However, number of axillary tillers/pot and herbage K percentage were increased significantly with each higher K rate. Potassium fertilization had no significant effect on root yield, primary shoot height, and herbage N percentage. It was concluded that the vegetative growth of oats is very responsive to N fertilization to the highest rate applied (200 kg N/ha), but responds only to the first increment of K (200 kg K/ha).     

Phosphorus–microbes interaction on growth,yield and phosphorus-use efficiency of irrigated cotton

The phosphorus-use efficiency of crops in high pH soil is low. A randomized complete block design in a 3 × 2 split-plot experiment was conducted on a high pH silt loam (Typic Ustochrepts) to evaluate whether P-solubilizing microbial (PSM) inocula were able to improve the P fertilization effects on irrigated cotton (Gossypium hirsutum L., cultivar CIM-482). Cotton was planted after seed treatment with PSM inoculation at 0, 22 and 44 kg P ha^?1. Results showed that soil microbial populations were significantly higher throughout the cotton-growing season in response to P fertilization and PSM inoculation. Both P fertilization and PSM inocula exerted a significant effect on cotton biomass and Puptake without an interaction. Economic analyses suggest that PSM inocula alone significantly increased P-use efficiency (8%), reduced cost and improved net income (by $36 ha^?1) of irrigated cotton production. Moreover, the relationship between relative yield and P fertilization with PSM inocula showed that 95% of the maximum yield of cotton was produced at 22 kg P ha^?1, whereas in the absence of PSM inocula, 95% relative yield was obtained at 36 kg P ha^?1, asaving of ～39% applied P with PSM inoculation.     

Soil chemical properties after long‐term n fertilization of bromegrass: Nitrogen rate

Abstract

Nitrogen (N) fertilizers increase yield and quality of grass forage, and may also alter soil chemical properties. A field experiment was conducted in south‐central Alberta to determine the effect of long‐term application of ammonium nitrate to bromegrass on concentration and downward mobility of soluble NO₃‐N, extractable NH₄‐N, P, Ca, Mg, and K, and total C and N in a Thin Black Chernozemic loam soil. The fertilizer was applied annually in early spring for 16 years at 0 to 336 kg N/ha. There was little accumulation of NO₃‐N in the soil at N rates of 112 kg/ha or less. However, at rates higher than 112 kg N/ha there was accumulation of NO₃‐N in the 15–30 and 30–60 cm layers, but very little in the 90–120 cm depth. The NH₄‐N accumulated in the 0–5 cm layer when the fertilizer was applied at rates between 168 to 280 kg N/ha and in the 5–10 cm layer at N rates exceeding 280 kg/ha. There was a decline in extractable P in soil with N application up to 84 kg N/ha rate, while it increased with high N rates. The increasing amounts of applied N resulted in a decline in extractable soil Ca, Mg and K, and this decrease was more pronounced in the 0–5,5–10,10–15, and 15–30 cm layers for K, 0–5 and 5–10 cm layers for Ca, and 0–5, 5–10, and 10–15 cm layers for Mg. There was a build‐up of total C and N in the surface soil with increasing rate of applied N.     

Effect of N and P fertilization on yield and quality of Kochia grown in the greenhouse

Abstract

The use of kochia (Kochia scoparia (L.) Schrad.) as a forage crop has recently generated considerable interest, but little is known about how fertilization affects yield and quality. Two greenhouse experiments were conducted; the first with a clay loam soil and 0, 67 and 135 kg P/ha, and the second with a sandy loam soil and extremely high rates of P, which were 0, 4.5, 9.0, 13.5 and 17.9 ton P/ha. Both had 0, 84, 168 and 252 kg N/ha in a complete factorial with the P levels. In the first experiment, dry matter yield, root dry matter yield and flowering percentage increased linearly with N, while Ca, P and oxalate percentage decreased quadratically with N. Oxalate levels were low with a mean of 1.98%. Phosphorus levels affected only P percentage, which increased quadratically with P level. No interactions were observed between N and P in the first experiment.

In the second experiment, the high levels of P increased dry matter yield, crude protein and oxalate percentages, especially at low N levels. For these three parameters, there was an interaction between N and P. Phosphorus percentage increased guadra‐tically with P level up to 2.85% P, but decreased quadratically with N level. No interaction between N and P was observed for P percentage. Phosphorus levels reduced Ca percentage, but N had no effect. Oxalate levels were higher in the second experiment, with a mean of 5.23%, which might cause toxicity problems to livestock.     

Effect of application rate of a nitrification inhibitor,dicyandiamide (DCD), on nitrification rate,and ammonia-oxidizing bacteria and archaea growth in a grazed pasture soil: An incubation study

Purpose

Dicyandiamide (DCD) has been used commercially in New Zealand to reduce nitrate leaching and N₂O emissions in grazed pastures. However, there is a lack of information in the literature on the optimum rate of DCD to achieve the environmental benefits while at the same time reducing the cost of the technology. The objective of this study was to determine the effect of DCD application rate on its effectiveness to inhibit ammonia oxidizer growth and nitrification rate in a grazed pasture soil.

Materials and methods

The soil was a Templeton silt loam (Immature Pallic Soil; Udic Haplustepts) collected from Lincoln University Research Dairy Farm with a mixed pasture consisting of perennial ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.) and was incubated alone (control) or with cow urine at 700 kg N/ha with 6 rates of DCD [0, 2.5, 5, 7.5, 10 (applied twice), 15 and 20 kg/ha] in incubation vessels. The incubation vessels were placed randomly in an incubator with a constant temperature of 12 °C. During 112 days of incubation, soil subsamples were taken at different time intervals to measure the concentrations of NO₃ ^?-N and NH₄ ⁺-N and the amoA gene copy numbers of ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA).

Results and discussion

DCD applied at all the different rates inhibited nitrification in urine-treated soils, but the effectiveness increased with DCD application rate. In addition, AOB growth and the amounts of nitrate-N in the soil were significantly related to the application rate of DCD. However, AOA population abundance showed no relationship to the application rate of DCD. The DCD rate at which the AOB growth rate and nitrate-N concentration were halved (effective dosage that causes 50 % reduction in nitrification rate, or ED₅₀) was about 10 kg DCD/ha.

Conclusions

These results suggest that DCD applied at relatively low rates still slowed down the nitrification rate, and the current recommended rate of 10 kg DCD/ha for DCD use in New Zealand grazed pastures would result in a 50 % reduction in nitrification rate in this soil. The actual rate of DCD application used would depend on the cost of the product and the environmental and agronomic benefits that would result from its use.     

Phytotoxicity and some interactions of the essential trace metals iron,manganese, molybdenum,zinc, copper,and boron

Abstract

The essential trace elements Fe, Mn, Zn, Cu, and B in high concentrations can produce phytotoxicities. Iron toxicity resulted from 5 × 10^‐4 M and 10^‐3 M FeSO₄, but not from equivalent amounts of FeEDDHA (ferric ethylenediamine di (o‐hydroxyphenylacetic acid) ). Leaf concentrations in bush beans of 465 μg Mn/g, 291 μg B/g, and 321 μg Zn/g all on the dry weight basis resulted in 27%, 45%, and 34% reduction in yields of leaves, respectively. Zinc was concentrated in roots while Mn and B concentrated in leaves. Solution concentrations of MnS0₄ of 10^‐3 and 10^‐2 M depressed leaf yields of bush beans by 63% and 83%, respectively, with 5140 and 10780 μg Mn/g dry weight of leaves. Copper concentrations were simultaneously increased and those of Ca were decreased. Bush bean plants grown in Yolo loam soil with 200 μg Cu/g soil had a depression in leaf yield of 26% (with 28. 8 μg Cu/g leaf); plants failed to grow with 500 μg Cu/g soil. A level of 10^‐3 M H₂MoO₄ was toxic to bush beans grown in solution culture. Leaves, stems, and roots, respectively, contained 710, and 1054, and 5920 μg Mo/g dry weight.     

Yield of alfalfa as influenced by levels of P and K fertilization

Abstract

This study was conducted to ascertain further the need for P and K fertilizers to obtain maximum herbage yields from alfalfa (Medicago sativa L.). Vernal alfalfa was established on a low K Piano silt loam (Typic Argiudoll) soil and topdressed with zero, 22.4, and 44.8 kg/ha of P in autumn of seeding year and with zero, 224, and 672 kg/ha of K as KC1 each autumn. The harvest schedule was three cuts annually at first flower; a schedule widely recommended in the North Lake states. No statistical significance was found for P levels nor for the P x K interaction; significance was found only for K levels. Maximum herbage yield was obtained with 224 kg/ha of K in the first harvest year, but with the 672 kg/ha of K rate in the second harvest year. Herbage K and Cl percentages and amounts removed from the soil increased significantly each year with each increase in K applied. Herbage P and N percentages were decreased significantly with the first increment of K. Residual herbage yields showed dramatically the influence of K fertilization on winter survival. All alfalfa stands with no K fertilization were killed completely. Residual yields and stands increased with each increase in K applied. Yield increase over the control was significant only with the second increment of K, while stands increased significantly with each increase in K applied. These data continue to confirm that high levels of soil K are needed for stand survival as well as for high herbage yields.     

The concentrations of fatty acids in organo-mineral particle-size fractions of a Chernozem

Fatty acids, the most abundant class of soil lipids, indicate pedogenetic processes and soil management. However, their quantitative distribution in organo‐mineral particle‐size fractions is unknown. The concentrations of n‐C_10:0 to n‐C_34:0 fatty acids both in whole soil samples and in the organo‐mineral particle‐size fractions of the Ap horizon of a Chernozem were determined (i) to evaluate the effects of long‐term fertilization and (ii) to investigate their influence on the aggregation of organo‐mineral primary particles. Quantification by gas chromatography/mass spectrometry (GC/MS) showed that long‐term fertilization with nitrogen, phosphorus and potassium (NPK) and farmyard manure (FYM) led to larger concentrations (25.8 µg g^?1) of fatty acids than in the unfertilized sample (22.0 µg g^?1). For particle‐size fractions of the unfertilized soil, the fatty acid concentrations increased from the coarse silt to the clay fractions (except for fine silt). Fertilization with NPK and FYM resulted in absolute enrichments of n‐C_21:0 to n‐C_34:0 fatty acids with a maximum at n‐C_28:0 in clay (×2.2), medium silt (×2.0), coarse silt (×1.8) and sand (×2.9) compared with the unfertilized treatment (the factors of enrichment are given in parentheses). New evidence for the aggregate stabilizing function of n‐C_21:0 to n‐C_34:0 fatty acids was shown by the characteristic pattern in size‐fractionated, disaggregated and aggregated samples. Highly significant correlations of fatty acid concentrations with organic C concentrations and specific surface areas are interpreted as indicators of (i) trapping of fatty acids in organic matter macromolecules and (ii) direct bonding to mineral surfaces. This interpretation was supported by the thermal volatilization and determination of fatty acids by pyrolysis‐field ionization mass spectrometry (Py‐FIMS).