Self-perceived oral health and orofacial aesthetics of cleft patients.

PURPOSE: To evaluate the self-perceived oral health and aesthetics of the dentition and jaw in patients with different types of oral cleft, measured by patient-reported outcome measures (PROMs). Additionally, to compare the results of the PROMs between cleft lip and or/palate (CL/P) patients and non-affected controls. METHODS: 420 CL/P patients treated at the cleft team of the Erasmus Medical Center, Rotterdam, The Netherlands, were included, and 138 non-cleft patients were recruited as control-group. Patient's perceptions were retrospectively evaluated using the CLEFT-Q Teeth for dental aesthetics at ages 8, 12 and 22, CLEFT-Q Jaw for jaw aesthetics at ages 12 and 22, and the Child Oral Health Impact Profile-Oral Symptoms Subscale (COHIP-OSS) for oral health at ages 8 and 12. One-way ANOVA was used to compare differences in oral health and aesthetic perceptions among age-groups, cleft types, as well as between cases and controls. RESULTS: CL/P patients were significantly less satisfied than controls with their dental aesthetics (p = 0.001). CL/P patients reported significantly lower satisfaction on CLEFT-Q Teeth scores at ages 8 and 12, than at 22 years (p < 0.001). Patients with the most extensive cleft phenotype, Cleft Lip and Palate (CLAP), reported lowest satisfaction on the CLEFT-Q Teeth. No differences in perceptions of oral health nor in aesthetics of the jaw were found in the different cleft types, ages, nor in study versus control group. CONCLUSION: This study found differences in self-perceived dental aesthetics: CL/P patients are less satisfied than non-affected controls. CLAP patients are least satisfied, but satisfaction increases with age.

Toward optimisation of water use efficiency in dryland pastures using carbon isotope discrimination as a tool to select plant species mixtures.

Pastoral agriculture is important for supplying global demand for animal products but pasture productivity is often water limited. Increased plant diversity has been shown to increase water use efficiency (ω) and productivity under water limitation but the optimal mix of species varies spatially, dependent on climate, soil type, and plant water requirements. Consequently, a cost-effective method to screen for high ω plant species and mixes in situ at farm scale is needed. Using carbon isotope discrimination (∆13C) to examine ω is attractive because the method integrates over useful time scales, does not modify the measurement environment, and is cost-effective. Field scale ω was measured using eddy covariance (EC) at two sites with contrasting plant diversity (2 species, 7 species) and compared to the seasonal progression of ω calculated from foliage ∆13C (ω∆). Soil water evaporation (ES) was removed from EC measured total ecosystem evaporation using a modelling approach and canopy ω (ωC) was calculated as gross primary production (GPP) divided by canopy evaporation. Mixed species foliage samples were harvested pre-grazing, dried, sub-sampled, ground, and the ratio of 13C to 12C was measured. A strong positive correlation was found between ω∆ and ωC at both study sites (r2 > 0.83, p < 0.01). In addition to bulk biomass samples, individual species were also harvested seasonally. Relative increases in both ω∆ and production for some species showed that manipulation of pasture species mixtures may lead to increased ω. Combined with production monitoring, ∆13C could be developed as a tool to optimise species selection for site specific climate and soil conditions to maximise ω and farm production and profit.

Can Incorporating Brassica Tissues into Soil Reduce Nitrification Rates and Nitrous Oxide Emissions?

New Zealand agriculture is composed predominantly of pastoral grazing systems; however, forage crops have been increasingly used to supplement the diet of grazing animals. Excreta from grazing animals has been identified as a main contributor of NO emissions. Some forage crops, such as brassicas ( spp.), contain secondary metabolites that have been identified to inhibit soil N cycling processes, and nitrification in particular. Our objective was to determine if secondary metabolites released from brassica tissues inhibited nitrification and reduced NO emissions when incorporated into soil, which was amended with a large amount of urea N (such as derived from urine patches deposited during grazing). Three brassica tissues (kale [ L.], turnip [ L.] bulb, and turnip leaf and stem) and ryegrass ( L.) tissue were incorporated into soil with and without urea solution, and NO, NO, and NH were measured during a 52-d incubation. All brassica tissues reduced urea-derived NO emissions relative to ryegrass tissues when incorporated into soil. According to the mineral N and microbial community data, this reduction, however, could not be attributed to inhibition of nitrification. Although there was less NO from urea in the brassica treatments, total NO emissions increased after incorporation of all tissue residues into soil, so this tradeoff must be explored if brassica tissues are to be considered as a tool for NO reduction.

Do glucosinolate hydrolysis products reduce nitrous oxide emissions from urine affected soil?

New Zealand agriculture is predominantly comprised of pastoral grazing systems and deposition of animal excreta during grazing has been identified as a major source of nitrous oxide (N2O) emissions. Nitrification inhibitors have been shown to significantly reduce nitrous oxide emissions from grazing pastoral systems, and some plants have been identified as having nitrification inhibiting properties. Brassica crops are one such example as they contain the secondary metabolite glucosinolate (GLS) whose hydrolysis products are thought to slow soil nitrogen cycling. Forage brassicas have been increasingly used to supplement the diet of grazing animals. The aim of this study was to determine if GLS hydrolysis products (phenylethyl isothiocyanate, 4-pent-1-yl isothiocyanate, 2-propenyl nitrile, 2 propenyl isothiocyanate, 4-pentene nitrile) produced in brassica crops reduced N2O emissions from soil amended with urea or animal urine. In the laboratory, some GLS hydrolysis products added with urea to soil were found to decrease N2O emissions and the most effective product (phenylethyl isothiocyante) reduced N2O emissions by 51% during the study. There was some evidence that the reduction in N2O emissions found in the lab could be attributed to inhibition of nitrification. Results suggest that the inhibition by GLS hydrolysis products was short-lived and, if considered for use, multiple applications may be necessary to achieve effective inhibition of N2O emissions. This reduction, however, was not observed under field conditions. Further investigation is required to test more GLS hydrolysis products to fully understand their impact on N2O emissions from urine affected soil.

Nitrogen transformation in a denitrification layer irrigated with dairy factory effluent.

Adoption of land-based effluent treatment systems can be constrained by the costs and availability of land. Sufficient land area is needed to ensure nitrate leaching from applied effluent is minimised. One approach to decrease required land area is to enhance N removal by denitrification. Layers of organic matter (100 mm thick) were installed below topsoil of a site irrigated with dairy factory effluent. These "denitrification" layers were tested to determine whether they could decrease nitrate leaching by increasing denitrification. Four plots (10x10 m2 each) were constructed with a denitrification layer installed at 300 mm below the surface, and N losses were measured in leachate using suction cups every 3 weeks for 19 months. N in leachate was compared with 4 control plots. Denitrifying enzyme activity, nitrate concentrations, and carbon availability were measured in samples collected from the denitrification layers. These measurements demonstrated that denitrification occurred in the layer; however, denitrification rates were not sufficiently high to significantly decrease nitrate leaching. Total N leaching was 296 kg N ha(-1) from control plots and 238 kg N ha(-1) from plots with denitrification layers; a total of 798 kg N ha(-1) was applied in effluent. More than 50% of the leached N to 40 cm was as organic N, presumably due to bypass flow. Other studies have demonstrated that thicker denitrification layers (more than 300 mm) can reduce nitrate leaching from small-scale septic tank drainage fields but this study suggests that it is probably not practical to use denitrification layers at larger scales.

What is soil organic matter worth?

The conservation and restoration of soil organic matter are often advocated because of the generally beneficial effects on soil attributes for plant growth and crop production. More recently, organic matter has become important as a terrestrial sink and store for C and N. We have attempted to derive a monetary value of soil organic matter for crop production and storage functions in three contrasting New Zealand soil orders (Gley, Melanic, and Granular Soils). Soil chemical and physical characteristics of real-life examples of three pairs of matched soils with low organic matter contents (after long-term continuous cropping for vegetables or maize) or high organic matter content (continuous pasture) were used as input data for a pasture (grass-clover) production model. The differences in pasture dry matter yields (non-irrigated) were calculated for three climate scenarios (wet, dry, and average years) and the yields converted to an equivalent weight and financial value of milk solids. We also estimated the hypothetical value of the C and N sequestered during the recovery phase of the low organic matter content soils assuming trading with C and N credits. For all three soil orders, and for the three climate scenarios, pasture dry matter yields were decreased in the soils with lower organic matter contents. The extra organic matter in the high C soils was estimated to be worth NZ$27 to NZ$150 ha(-1) yr(-1) in terms of increased milk solids production. The decreased yields from the previously cropped soils were predicted to persist for 36 to 125 yr, but with declining effect as organic matter gradually recovered, giving an accumulated loss in pastoral production worth around NZ$518 to NZ$1239 ha(-1). This was 42 to 73 times lower than the hypothetical value of the organic matter as a sequestering agent for C and N, which varied between NZ$22,963 to NZ$90,849 depending on the soil, region, discount rates, and values used for carbon and nitrogen credits.

Land application of domestic effluent onto four soil types: plant uptake and nutrient leaching.

Land application has become a widely applied method for treating wastewater. However, it is not always clear which soil-plant systems should be used, or why. The objectives of our study were to determine if four contrasting soils, from which the pasture is regularly cut and removed, varied in their ability to assimilate nutrients from secondary-treated domestic effluent under high hydraulic loadings, in comparison with unirrigated, fertilized pasture. Grassed intact soil cores (500 mm in diameter by 700 mm in depth) were irrigated (50 mm wk(-1)) with secondary-treated domestic effluent for two years. Soils included a well-drained Allophanic Soil (Typic Hapludand), a poorly drained Gley Soil (Typic Endoaquept), a well-drained Pumice Soil formed from rhyolitic tephra (Typic Udivitrand), and a well-drained Recent Soil formed in a sand dune (Typic Udipsamment). Effluent-irrigated soils received between 746 and 815 kg N ha(-1) and 283 and 331 kg P ha(-1) over two years of irrigation, and unirrigated treatments received 200 kg N ha(-1) and 100 kg P ha(-1) of dissolved inorganic fertilizer over the same period. Applying effluent significantly increased plant uptake of N and P from all soil types. For the effluent-irrigated soils plant N uptake ranged from 186 to 437 kg N ha(-1) yr(-1), while plant P uptake ranged from 40 to 88 kg P ha(-1) yr(-1) for the effluent-irrigated soils. Applying effluent significantly increased N leaching losses from Gley and Recent Soils, and after two years ranged from 17 to 184 kg N ha(-1) depending on soil type. Effluent irrigation only increased P leaching from the Gley Soil. All P leaching losses were less than 49 kg P ha(-1) after two years. The N and P leached from effluent treatments were mainly in organic form (69-87% organic N and 35-65% unreactive P). Greater N and P leaching losses from the irrigated Gley Soil were attributed to preferential flow that reduced contact between the effluent and the soil matrix. Increased N leaching from the Recent Soil was the result of increased leaching of native soil organic N due to the higher hydraulic loading from the effluent irrigation.

Three approaches to define desired soil organic matter contents.

Soil organic C is often suggested as an indicator of soil quality, but desirable targets are rarely specified. We tested three approaches to define maximum and lowest desirable soil C contents for four New Zealand soil orders. Approach 1 used the New Zealand National Soils Database (NSD). The maximum C content was defined as the median value of long-term pastures, and the lower quartile defined the lowest desirable soil C content. Approach 2 used the CENTURY model to predict maximum C contents of long-term pasture. Lowest desirable content was defined by the level that still allowed recovery to 80% of the maximum C content over 25 yr. Approach 3 used an expert panel to define desirable C contents based on production and environmental criteria. Median C contents (0-20 cm) for the Recent, Granular, Melanic, and Allophanic orders were 72, 88, 98, 132 Mg ha(-1), and similar to contents predicted by the CENTURY model (78, 93, 102, and 134 Mg ha(-1), respectively). Lower quartile values (54, 78, 73, and 103 Mg ha(-1), respectively) were similar to the lowest desirable C contents calculated by CENTURY (55, 54, 67, and 104 Mg ha(-1), respectively). Expert opinion was that C contents could be depleted below these values with tolerable effects on production but less so for the environment. The CENTURY model is our preferred approach for setting soil organic C targets, but the model needs calibrating for other soils and land uses. The statistical and expert opinion approaches are less defensible in setting lower limits for desirable C contents.

Soil quality at a national scale in New Zealand.

New Zealand is a signatory to international conventions on environmental performance, and soil quality information is needed for reporting both at a national and regional level. Soil quality was measured at 222 sites in five regions of New Zealand (12 soil orders and 9 land-use categories). Topsoil (0-100 mm) properties measured were total carbon and nitrogen, potentially mineralizable N, pH, Olsen P, cation exchange capacity, bulk density, total porosity, macroporosity, and total available and readily available water. Our objectives were to gauge the representativeness of the sample, determine the contribution from land use or soil order to variability, rationalize the data set, and identify concerns for long-term sustainable land use. Soil and land use combinations were both under- or overrepresented in the data set compared with national distribution. Soil order and land-use categories explained 55 to 76% of the variance in soil properties. Total C contents of pastures were comparable with indigenous forest soils, but pastures were less acidic and with higher N and P contents. Plantation forests had characteristics similar to indigenous forests on comparable soils. Cropland soils comprised <1% of the national land cover and generally had high inorganic fertility and low organic matter, with evidence of compaction. Seven characteristics (total C, total N, mineralizable N, pH, Olsen P, bulk density, and macroporosity) explained 87% of the total variability. The findings are being used by monitoring agencies to raise awareness about soil quality in the wider community, set land management guidelines, and develop policies.

Five years of nitrate removal, denitrification and carbon dynamics in a denitrification wall.

Denitrification walls are a useful approach for removing nitrate from shallow groundwater, but little is known about the sustainability of nitrate removal, which is dependent on the continued supply of organic carbon to denitrifying bacteria. To address this question, we monitored nitrate removal, denitrification and carbon dynamics in a pilot-scale denitrification wall for 5 yr. The wall continuously removed more than 95% of the incoming nitrate in groundwater, which ranged from 5 to 15 mg N L(-1). We did not detect decreases in total carbon during the 5-yr study. Available carbon declined for the first 200 days after the wall was constructed but has since remained relatively constant. While microbial biomass has varied between 350 and 550 microg C g(-1) there was no downward trend, suggesting that carbon availability was not limiting the size of the microbial population. However, there was a large decrease in denitrifying population, as indicated by declines in denitrifying enzyme activity. Despite this decrease, denitrification rates have remained high enough to remove nitrate from groundwater and denitrification was limited by nitrate rather than by carbon. Our data demonstrates that there was sufficient available carbon in this denitrification wall to support denitrification and nitrate removal for at least 5 yr.

Regulation of nitrous oxide emissions from soils irrigated with dairy farm effluent.

Animal slurries and effluents are commonly applied to soil as a source of organic N fertilizer. By increasing inorganic N, applying animal effluents may also increase soil nitrous oxide (N2O) emissions. Our objectives were to (i) determine if dairy farm effluent (DFE) irrigation increased short-term N2O emissions from a surface-drained peat soil and a freely drained mineral soil and (ii) see if this increase could be attributed to increased N availability, increased soil water content, or a combination of both factors. We measured short-term N2O emissions following DFE irrigation in spring and autumn, using closed chambers. Nitrous oxide emissions from DFE-irrigated soils (50 kg N ha(-1), 20-mm hydraulic loading) were compared with soils receiving inorganic nitrogen and water (50 kg N ha(-1), 20 mm), inorganic N only (50 kg N ha(-1)), water only (20 mm), and no treatment. Nitrous oxide emissions increased immediately following DFE irrigation to both soils, and were generally greater than emissions following the application of inorganic fertilizer with water. Increased N20 emissions following DFE irrigation coincided with increased soil water contents and mineral N and CO2 emissions. We suggest that DFE application increased N2O emissions more than inorganic N fertilizer by enhancing denitrification either by increasing C availability and/ or decreasing soil aeration following increased respiration. These findings suggest that the proportion of N applied to the soil and emitted as N2O may at times be greater for organic N fertilizers than inorganic N fertilizers, particularly if the organic N fertilizer contains sufficient available C to enhance denitrification.

Anaerobic Decomposition and Denitrification during Plant Decomposition in an Organic Soil.

Nitrate concentrations in groundwater have been shown to be reduced during passage through riparian soils and a possible mechanism for this reduction is bacterial denitrifieation. For denitrification to occur there must be sufficient available C as an energy source. We examined the competition for organic substrate between microbial processes during the anaerobic decomposition of plant matter in a laboratory study. Fresh and senescent pine needles (Pinus radiata D. Don) and watercress leaves (Rorippa nasturtium-aquaticum L.Hayek) were added to an organic riparian soil, incubated anaerobically for 90 d and production of CO2 and CH4 measured. At 9-d intervals NO3 and acetylene were added to a replicate and production of CO2 , CH4 , and N2 O was followed. In the absence of NO3 , watercress produced the most CO2 and CH4 (21% of added C), followed by fresh pine needes (10%), and senescent pine needles (6%). First-order rate constants calculated for gaseous C production were 0.033 d-1 , 0.0088 d-1 , and 0.0071 d-1 for watercress, fresh, and senescent pine needles, respectively. As plant tissue became increasingly decomposed via fermentation, less N2 O and CO2 was produced following NO3 addition, presumably because the remaining plant matter was more resistant to further degradation. Denitrification and CO2 production in the watercress and fresh pine needle treatments were up to 5 times higher than that measured in the senescent pine needle treatment. As the same amount of C was added to all treatments, these results suggested that the lability of added C was of greater importance than the quantity of C added in regulating microbial response. The response of denitrifying bacteria to the addition of NO3 was rapid, even after 99 d of incubation in the absence of either NO3 or oxygen as an electron acceptor. This suggested that denitrifying bacteria could survive and compete for C in riparian soils where NO3 concentrations fluctuate.