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The nutrient content of drainage water from Histosols located in New York was monitored from June 1975 through July 1977. Continuous flow records and nutrient concentration data obtained from daily composite samples were used to calculate annual nutrient outputs which ranged from 0.6 to 30.7 kg/ha for PO4−‐P, 39.2 to 87.5 kg/ha for NO3−‐N, and <1.0 to 1.9 kg/ha for NH4+‐N. Nutrient concentrations in the drainage water increased with increasing flow, so that the greatest output of nutrients was during late winter and spring high‐flow events. Maximum observed concentrations were 35 mg/liter for NO3−‐N and 10 mg/liter for PO43−‐P. The amount of N lost in drainage water was similar at all sites and was about 10% of that mineralized; the remainder was presumed to be denitrified. The fiftyfold variability in phosphorus output appeared to be related to interactions within the soil profile rather than fertilizer practices, although these probably contributed to the generally high levels found. It was concluded that fertilizer nitrogen additions were unlikely to affect the quantity of NO3−leached. The study showed that organic soils can contribute to N and P in land runoff in much greater proportions than indicated by their area.

The C2H2‐block method was used to measure denitrification in a maize (Zea maysL.) field over the 85‐d period between sidedressing with N fertilizer and harvest. Measurement locations were changed weekly in order to avoid problems associated with microbial utilization of C2H2and inhibition of nitrification. Nitrous oxide (N2O) fluxes were measured both with and without C2H2addition to soil. Without C2H2addition to soil, 0.3 kg N ha−1was evolved from both unfertilized and Ca(NO3)2treated soil, whereas 2.5 kg N ha−1was evolved from urea treated soil. This difference was attributed to formation of N2O during nitrification of NH+4liberated from urea. With C2H2addition to soil, 1.6, 2.0, and 2.4 kg N ha−1were evolved as the result of denitrification in the zero N, Ca(NO3)2, and urea treated sites, respectively. Total gaseous N loss from a particular N treatment was approximated by adding together the N2O‐N loss with and without C2H2addition to soil. The gaseous N loss associated with fertilizer addition was <3% of that applied. The ratio of N2/N2O evolved without C2H2addition to soil was estimated to be in the range of 4:1 to 7:1 for the zero N and Ca(NO3)2treatments and about 1:1 for the urea treatment. Denitrification was responsible for at least 80% of the measured gaseous N loss from the zero N and Ca(NO3)2treatments. About equal amounts of gaseous N loss from the urea treatment occurred via denitrification and during nitrification of liberated NH+4.

The effect of complexing agents on Fe mobility was investigated using a simulated root‐soil system that consisted of 0.24‐mm o.d. cellulose fibers embedded in a clay‐agar matrix. Complexing agents diffused into the clay‐agar matrix from a solution flowing through the fibers and their effect on Fe flux to the fiber surface was determined by following Fe concentration in the effluent solution from the fibers. Experiments with the chelating agents ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), ethylenediamine di‐(o‐hydroxyphenylacetic acid) (EDDHA), and ethylene glycol‐bis‐(2‐amino‐ethylether) tetraacetic acid (EGTA) demonstrated that solubilization of Fe qualitatively followed patterns predicted from known thermodynamic stability constant‐pH relationships. The concentration of Fe in the fibers 24 h after introduction of either EDTA, DTPA, or EDDHA was increased from close to 0 to 30 to 100 g Fe L−1, whereas EGTA had no measurable effect on Fe solubility. The measured fluxes of Fe were compared with calculations based on diffusion and reaction. An equilibrium model, where the complexing agent was assumed to equilibrate instantaneously with the soil (reaction rate constant Kr= 1), predicted concentrations of Fe 103times greater than those observed. A first‐order kinetic model, which was solved by numerical methods, gave results similar to those found experimentally when Krwas on the order of 10−7. The partial success of the thermodynamic stability constant approach was reconciled with the kinetic model by considering Krto combine both kinetic and equilibrium factors.

Gaseous N loss via denitrification can be measured with static flux chambers when acetylene (C2H2) is used to block nitrous oxide (N2) reduction. This paper describes a method for the introduction of C2H2at low concentrations into the soil by diffusion. The method utilizes an above‐ground manifold connected to diffusion tubes inserted in the soil and C2H2flows through the manifold at a rate of 0.33 mL s−1. Acetylene levels in the soil atmosphere within the flux chamber site ranged from 0.16 to 2.07 mol m−3, and the apparatus did not alter CO2fluxes as measured by a static chamber method.

The quantities of N mineralized when columns of Histosols were incubated at field capacity for periods up to 28 days corresponded to 500‐600 kg N/ha per year without correction for N lost by denitrification. An absorption train utilizing molecular sieve 5Å to collect N2O was used in denitrification experiments. Under an argon stream, 52‐53% of the added NO3‐‐N was recovered as N2O, whereas the maximum concentration of N2O accumulating in the headspace of closed vessels amounted to 65% of the added NO3‐‐N. The quantity of N2O either collected or accumulating in a headspace was reduced to 15‐41% of the NO3‐‐N denitrified when a second addition of NO3‐was made to the soils. Denitrification occurred in both drained and flooded soil columns amended with NO3‐. The N2O recovered ranged from 2.5‐9% and 9‐19% of the NO3‐‐N denitrified in the drained and flooded columns, respectively. From 78‐98% of the N2O was recovered in leachate from the flooded columns and the corresponding range for the drained columns was 11‐52%.

To understand nutritional rickets in Bangladesh better, 14 rachitic and 13 'unaffected' children were evaluated. Seventy per cent of children with active rickets had no evidence of either vitamin D deficiency or familial rickets. Rickets in Bangladesh is probably related to calcium deficiency. Abnormalities in 'unaffected' children suggest that subclinical calcium insufficiency is common.

An enzyme preparation from 2,4-dichlorophenoxyacetate-grown Arthrobactersp. converted cis,cis-2,4-dichloromuconate to chloromaleylacetate. The enzyme lactonizing the dichloromuconate to yield 2-chloro-4-carboxymethylene but-2-enolide was separated from the butenolide-delactonizing enzyme.