Shabtai Bittman

Soil and fertilizer phosphorus: Effects on plant P supply and mycorrhizal development

Plants require adequate P from the very early stages of growth for optimum crop production. Phosphorus supply to the crop is affected by soil P, P fertilizer management and by soil and environmental conditions influencing P phytoavailability and root growth. Phosphorus uptake in many crops is improved by associations with arbuscular mycorrhizal fungi. Cropping system and long-term input of P through fertilizers and manures can influence the amount and phytoavailability of P in the system and the development of mycorrhizal associations. Optimum yield potential requires an adequate P supply to the crop from the soil or from P additions. Where early-season P supply is low, P fertilization may improve P nutrition and crop yield potential. Alternately, under low-P conditions, encouragement of arbuscular mycorrhizal associations may enhance P uptake by crops early in the growing season, improving crop yield potential and replacing starter fertilizer P applications. Soil P supply that exceeds P requirements of t...

Global Chemical Composition of Ambient Fine Particulate Matter for Exposure Assessment

Epidemiologic and health impact studies are inhibited by the paucity of global, long-term measurements of the chemical composition of fine particulate matter. We inferred PM2.5 chemical composition at 0.1° × 0.1° spatial resolution for 2004–2008 by combining aerosol optical depth retrieved from the MODIS and MISR satellite instruments, with coincident profile and composition information from the GEOS-Chem global chemical transport model. Evaluation of the satellite-model PM2.5 composition data set with North American in situ measurements indicated significant spatial agreement for secondary inorganic aerosol, particulate organic mass, black carbon, mineral dust, and sea salt. We found that global population-weighted PM2.5 concentrations were dominated by particulate organic mass (11.9 ± 7.3 μg/m3), secondary inorganic aerosol (11.1 ± 5.0 μg/m3), and mineral dust (11.1 ± 7.9 μg/m3). Secondary inorganic PM2.5 concentrations exceeded 30 μg/m3 over East China. Sensitivity simulations suggested that population-weighted ambient PM2.5 from biofuel burning (11 μg/m3) could be almost as large as from fossil fuel combustion sources (17 μg/m3). These estimates offer information about global population exposure to the chemical components and sources of PM2.5.

Enhancing Soil Infiltration Reduces Gaseous Emissions and Improves N Uptake from Applied Dairy Slurry

Rapid infiltration of liquid manure into the soil reduces emissions of ammonia (NH(3)) into the atmosphere. This study was undertaken to assess the effects of two low-cost methods of assisting infiltration of applied dairy slurry on emissions of NH(3), nitrous oxide (N(2)O), and on crop N uptake. The two methods were removing of solids by settling-decantation to make the manure less viscous and mechanically aerating the soil. Ammonia emissions were measured with wind tunnels as percentage of applied total ammoniacal nitrogen (TAN) while emissions of N(2)O were measured with vented chambers. Mechanically aerating the soil before manure application significantly reduced emissions of NH(3) relative to the nonaerated soil in spring (38.6 to 20.3% of applied TAN), summer (41.1 to 26.4% of applied TAN) and fall (27.7 to 13.6% of applied TAN) trials. Decantation of manure had no effect on NH(3) emissions in spring, tended to increase emissions in summer and significantly decreased emissions in fall (30.3 to 11.1% of applied TAN). Combining the two abatement techniques reduced NH(3) emission by 82% in fall, under cool weather conditions typical of manure spreading. The two abatement techniques generally did not significantly affect N(2)O emissions. Uptake of applied N by Italian ryegrass (Lolium multiflorum Lam.) was generally significantly greater with decanted than from whole manure but the effect of aeration was generally small and not significant. The study shows that low cost methods that assist manure infiltration into the soil may be used to greatly reduce ammonia loss without increasing N(2)O emissions, but efficacy of abatement methods is affected by weather conditions.

Odor Measurements for Manure Spreading Using a Subsurface Deposition Applicator

Odor emissions during manure spreading events have become a source of concern, particularly where farms are located nearby urban areas. The objective of the present study was to compare odor concentrations and odor emission rates due to pig manure application using two different types of applicators, a sub‐surface deposition system and a conventional splash‐plate applicator. Air samples were collected using a Surface Isolation Flux Chamber and the “bag‐in‐vacuum chamber” techniques, at 0.5, 1.5 and 2.5 hours after manure application. A three‐station forced‐choice dynamic dilution olfactometer was used by an odor panel for determining odor concentration. Preliminary results indicated that with the sub‐surface deposition system applicator odor emission rate was reduced by 8% to 38% compared to that of the conventional splash‐plate applicator. The highest reduction in odor strength and odor emission rate was observed in the most offensive period after manure application. The sub‐surface deposition system may be a solution for hog producers who wish to reduce odor complaints from applying manure without the cost and problems associated with deep injection systems.

Precision placement of separated dairy sludge improves early phosphorus nutrition and growth in corn ( L.).

Efficient use of manure nutrients by crops is necessary to minimize losses to the environment. This field study examined the possibility of replacing side-banded mineral P with precision-placed high-P sludge (6.2-11.0% dry matter) obtained after settling dairy manure slurry. The sludge was injected at about 30 kg P ha (36.0-51.2 m ha) into the soil at corn row spacing, and the corn was planted 5, 10, and 15 cm beside the injection furrow. Controls included no added P and side-banded commercial P fertilizer. The treatments were tested on corn with low and high root colonization by arbuscular mycorrhizae (AM). The study showed that sludge did not impede AM root colonization, corn germination, or seedling growth. Corn plants with both high and low levels of AM colonization responded to the sludge from the three-leaf stage and showed the greatest benefit at the six-leaf stage. Corn responded more to sludge placed at 5 than at 15 cm from the corn rows, whereas the response at the 10-cm spacing was intermediate. There was little difference in seedling growth or final harvest parameters between the side-banded fertilizer P and the 5-cm sludge treatment. The results show a new way to use manure nutrients, namely precision-placement sludge for corn. This may obviate the need for chemical fertilizers for improving farm nutrient balances. Other anticipated benefits are less energy use for hauling and injection of the sludge fraction and reduced risk of nutrient loss by runoff and volatilization (ammonia) and nuisance odors due to injection.

Monthly NH3 emissions from poultry in 12 Ecoregions of Canada.

Management of ammonia (NH3) is a multi faceted issue for farmers. It is simultaneously a toxicant that can affect farm worker and animal health, a volatile plant nutrient that is expensive to replace if lost, and a potential contributor to environmental degradation. The environmental implications have important spatial and temporal dimensions, beyond the farm. This paper describes a model developed to estimate NH3 emissions from poultry (broiler, layer and turkey) production in 2780 mapping units across Canada on a monthly time scale. It includes estimates of daily emission peaks within critical months. The results will contribute to estimates of haze and atmospheric aerosol production, as well as contributions to other potential impacts such as eutrophication of sensitive ecosystems. The model is based on a detailed survey of farm practices. Emissions vary strongly throughout the year, and in many regions there are peak emissions in early spring and late fall, associated with landspreading of manure. The...

A review of agricultural land use by shorebirds with special reference to habitat conservation in the Fraser River Delta, British Columbia

Many estuaries worldwide are important habitats for shorebirds. Agricultural fields adjacent to food-rich intertidal areas can provide roosting and feeding habitat, particularly at high tide. The Fraser River Delta (FRD) contains rich agricultural land and is Canada’s most important non-breeding site for shorebirds. We review and synthesize recent studies that have investigated agricultural land as non-breeding habitat for shorebirds in the FRD using radio-tracking, day-time and night-time surveys, stable isotope analysis of blood samples, examination of prey in stomach and faecal samples, and farmer surveys regarding field management. The three primary shorebirds studied in the FRD were dunlin (Calidris alpina pacifica), black-bellied plover (Pluvialis squatarola), and killdeer (Charadrius vociferus). Field use is mainly nocturnal for dunlin, but diurnal for black-bellied plovers and killdeer. Dunlin and black-bellied plovers mainly use bare or winter cover crop fields, preferring short cover. Killdeer m...

Season of year effect on response of orchardgrass to N fertilizer in a maritime climate

This study compared the response of harvests taken in May, June, August and September-October in terms of crop responses (yield, N uptake, and concentrations of crude protein and nitrate) to N fertilizer and residual soil nitrate and ammonium. Three trials were conducted in south coastal British Columbia in 1990–1992 to evaluate the response of an established sward of orchardgrass (Dactylis glomerata L.) to a range of N fertilizer rates. Both yields and daily crop growth rates were highest in cut 1, lowest in cut 4 and intermediate in cuts 2 and 3. For all four cuts, 95 and 90% of maximum yield was attained at about 136 and 82 kg ha-1 of applied N, respectively. Crop N supply from non-fertilizer sources ranged from 36 to 90 kg N ha-1, of which about 52% was attributed to nitrate present in the soil prior to growth and about 48% was N released from the soil, translocated from roots or deposited from the atmosphere. At 95% of maximum yield, crude protein concentrations ranged from 147 g kg-1 in the higher y...

Sensitivity analysis of alternative model structures for an indicator of ammonia emissions from agriculture

Ammonia (NH3) emission from agriculture is an environmental and health concern in many nations, and has trans-border impacts. Direct toxicity, terrestrial eutrophication and production of inhalable aerosols (< 2.5 µm diameter) are the specific concerns. Canada, among other northern hemisphere nations, has computed a national inventory of NH3 emissions, and a new emission inventory estimate is being prepared jointly under the National Agri-Environmental Health Analysis and Reporting Program (NAHARP) and National Agri-Environmental Standards Initiative (NAESI). However, there has been a rapid evolution in the models used, and a concomitant change in the NH3-specific data required. This paper compares several model structures and options using Monte Carlo simulation and sensitivity analysis methods. The results indicate the more recent models, that compute a mass balance of NH3 from excretion to landspreading, have tended to focus uncertainty onto the dietary efficiency of animal N nutrition. After excretion...

Nitrogen status of pollen donor affects kernel set and yield components in corn

ABSTRACT Nitrogen (N) status of corn plants influences yield performance through adjustment of yield components. Physiological function of corn pollen produced under N-stressed conditions has not drawn enough attention in genotype selection and breeding programs. The object of this study was to assess effects of N nutrition of the pollen donor on kernel set and yield components of the pollen recipient in a field trial by using a restricted pollination procedure. Pollen from plants receiving 0 and 240 kg N ha−1 was manually applied to plants receiving 0, 80, 160, and 240 kg N ha− 1 during silk emergence. The high rate of N fertilizer applied to the pollen donor significantly increased kernel number, kernel weight, harvest index, and aboveground biomass in the pollen recipient. The effect of N nutrition of the pollen donor was similar at all N levels that were applied to the pollen recipient so the interaction was not significant for any of the variables.