The environmental yardstick for pesticides: a practical indicator used in the Netherlands

The environmental yardstick for pesticides has been developed as a tool for farmers to select pesticides with the least environmental impact and to quantify the impact of their use at the crop/farm level, regional level and national level. For each pesticide the yardstick assigns environmental impact points for the risk to water organisms, the risk of groundwater contamination and the risk to soil organisms. It is presently used in the Netherlands as a management tool for farmers and technical consultants, as a tool for monitoring the environmental performance of farmers, as a tool for setting standards for ecolabels and as a policy evaluation tool.     

Use of simulation models to evaluate irrigation performance including water productivity, risk and system analyses

 Worsening water scarcity will increase pressure to use water more productively. In the classical view of irrigation research, some important aspects are often ignored: the total water balance approach, productivity of water, food security, and irrigation-system level analyses. These four approaches were evaluated using a detailed agro-hydrological model applied to an irrigation system in western Turkey. Emphasis was placed on the two dominant crops in the area: cotton and grapes. According to the classical point of view, the only result would be to irrigate the cotton with 1000 mm and the grapes with 800 mm. From the water productivity point of view, however, the water productivity of grapes appeared to be maximal without any irrigation; while for the cotton, irrigation at 600 mm maximizes water productivity. To minimize risks and increase yield stability, grapes perform better than cotton. Finally, from the irrigation system point of view, decisions can be made about the desirable cropping pattern and the distribution of water between crops. With limited amounts of water available for irrigation, a cropping pattern consisting mainly of grapes is desired; while with higher water availability, a mixture of cotton and grapes is preferable. The methods presented provide a clear methodology with which to achieve the most productive use of water. Received: 3 June 1999     

Copper,Chromium, and Arsenic Adsorption and Equilibrium Modeling in An Iron-Oxide-Coated Sand,Background Electrolyte System

The adsorption of copper, chromate, and arsenate (CCA)onto iron-oxide-coated sand (IOCS) was examined insingle-metal and mixed-metal systems. Copper andarsenate were strongly adsorbed or formed inner-spheresurface complexes with the IOCS surface while chromatewas weakly adsorbed or formed an outer-sphere surfacecomplex with the IOCS surface. Copper adsorption byIOCS slightly increased in the presence of arsenatebut was not affected by the presence of chromate. Arsenate adsorption was not affected by the presenceof copper and/or chromate. Chromate adsorptionincreased in the presence of copper by the combinationof electrostatic effects and possiblesurface-copper-chromate ternary complex formation. The presence of arsenate significantly decreasedchromate adsorption due to competition for adsorptionsites and electrostatic effects. Using inner-spheresurface complexation constants for copper and arsenateand outer-sphere surface complexation constants forchromate, the triple-layer model (TLM) was successfulin describing adsorption of copper, chromate, andarsenate in single-solute systems. The modelindicated that each metal uses a different number ofadsorption sites. For CCA metals-IOCS systems, theequilibrium constants determined from single-solutesystems were not able to predict adsorption frommulti-solute systems. The TLM does not currentlyaccount for the heterogeneity of oxide surface sitesand the formation of ternary complexes and/or solidphases that do not exist in single-solute systems.     

Organic Halogens in Landfill Leachates

Using a group parameter, totalorganic halogens (TOX), high TOX concentrationswere found in leachates and leachate contaminatedgroundwaters at two Danish mixed sanitary andhazardous waste sites. With commonly used screeningprocedures for organic contaminants, the individualhalogenated organic compounds behind the high TOXcould not be found. Conversely, part of the TOX couldbe attributed to halogenated humic substances that cannot be analysed with conventional organic contaminantanalyses. Even though TOX can still be considered anindicator of leachate contamination in the aquifers,attempts to identify the halogenated contaminantsbehind the TOX using screening methods such as GC-MSwill be unsuccessful in most cases.     

Optimal feed level during the transition period to achieve faster farrowing and high colostrum yield in sows

This study aimed to determine the optimal supply of lactation feed during the transition period to minimize farrowing duration (FD) and maximize colostrum yield (CY) and quality with the overall aim of reducing piglet mortality. A total of 48 sows were stratified for body weight and assigned to six levels of feed supply (1.8, 2.4, 3.1, 3.7, 4.3, and 5.0 kg/d) from day 108 of gestation until 24 h after the onset of farrowing. The number of total born, live-born, and stillborn piglets; birth time and birth weight of each piglet; and frequency of farrowing assistance (FA) was recorded, and blood samples were obtained from newborn piglets at birth. Live-born piglets were further weighed at 12 and 24 h after birth to record weight gain, which in turn was used to estimate intake and yield of colostrum. Colostrum samples were collected at 0, 12, 24, and 36 h after the onset of farrowing. FD was shortest (4.2 h) at intermediate (3.7 kg/d), longest (7.1 to 7.6 h) at low (1.8 and 2.4 kg/d), and intermediate (5.6 to 5.7 h) at high (4.3 and 5.0 kg/d) feed intake (P = 0.004; mean comparison). FA was lowest (0.7% to 0.8%) at intermediate feed intake (3.7 and 4.3 kg/d) and substantially elevated (4.3% to 4.7%) at both lower and higher feed intake (P = 0.01; mean comparison). The cubic contrast revealed 4.1 kg/d as the optimal feed intake to achieve the shortest FD and to minimize FA. Newborn piglets from second-parity sows were less vital than piglets from gilts as evaluated by blood biochemical variables immediately after birth. CY was greatest at 3.1 kg/d (P = 0.04), whereas the cubic contrast revealed 3.0 kg/d as the optimal feed intake to maximize CY. Concentrations of colostral components were affected by the diet, parity, and their interaction except for lactose concentrations. In conclusion, the study demonstrated the importance of proper feed level during the transition period on sow productivity. Moreover, this study estimated 4.1 and 3.0 kg/d as the optimal feed intake during the transition period to improve farrowing characteristic and CY, respectively, and these two feed intake levels supplied daily 38.8 MJ metabolizable energy (ME) and 23.9 g standardized ileal digestible (SID) lysine (3.0 kg/d) or 53.0 MJ ME and 32.7 g SID lysine (4.1 kg/d). The discrepancy of optimal feed intake for optimal farrowing and colostrum performance suggests that it may be advantageous to lower dietary lysine concentration in the diet fed prepartum.     

Effect of sample volume size and sampling method on feline longitudinal myocardial velocity profiles from color tissue Doppler imaging

ObjectivesThe aims of this study were to compare the effect of sample volume (SV) size settings and sampling method on measurement variability and peak systolic (s′), and early (e′) and late (a′) diastolic longitudinal myocardial velocities using color tissue Doppler imaging (cTDI) in cats.AnimalsTwenty cats with normal echocardiograms and 20 cats with hypertrophic cardiomyopathy.MethodsWe quantified and compared empirical variance and average absolute values of s′, e′ and a′ for three cardiac cycles using eight different SV settings (length 1,2,3 and 5 mm; width 1 and 2 mm) and three methods of sampling (end-diastolic sampling with manual tracking of the SV, end-systolic sampling without tracking, and random-frame sampling without tracking).ResultsNo significant difference in empirical variance could be demonstrated between most of the tested SVs. However, the two settings with a length of 1 mm resulted in a significantly higher variance compared with all settings where the SV length exceeded 2 mm (p < 0.001). There was an overall significant effect of sampling method on the variability of measurements (p = 0.003) and manual tracking obtained the lowest variance. No difference in average values of s′, e′ or a′ could be found between any of the SV settings or sampling methods.ConclusionWithin the tested range of SV settings, an SV length of 1 mm resulted in higher measurement variability compared with an SV length of 3 and 5 mm, and should therefore be avoided. Manual tracking of the sample volume is recommended.     

Potato (Solanum spp.) production using apical cuttings and tuberlets under three contrasting environments of Vietnam

Potato production from rooted apical cuttings or from small tubers (l–20g) produced in high density beds has great potential in Asia. This is particularly important in non-traditional warmer environments. This research was conducted to assess the feasibility of producing many small tubers in high density beds. A second objective compared tubers from beds with transplanted rooted cuttings and traditional seed tubers for growth and yield in the field. Tuberlet production in beds exceeded 2000/m² with a density of 1000 plants/m² under optimal growing conditions while under high temperatures only about 1.25 tuberlets/plant were produced. In field experiments, transplanted cuttings yielded 20 t/ha in the mid and high elevation areas, only slightly less than tuberlets of 5–10g while at the hot site, yields were generally only 8 to 10 t/ha for both materials. Larger healthy seed tubers produced significantly higher yields at the low and high elevation sites. Tuberlets of 1–5g were also able to give yields of 20 t/ha in the mid-elevation site. These results indicate that cuttings and small tuberlets are two ways of growing potatoes which need to be further evaluated for socioeconomic assessment by farmers.     

Microbial remediation of a pentachloronitrobenzene-contaminated soil under Panax notoginseng: A field experiment

Pentachloronitrobenzene (PCNB) is an organochlorine fungicide that is mainly used in the prevention and control of diseases in crop seedlings. Microbial removal is used as a promising method for in-situ removal of many organic pesticides and pesticide residues. A short-term field experiment (1 year) was conducted to explore the potential role of a PCNB-degrading bacterial isolate, Cupriavidus sp. YNS-85, in the remediation of a PCNB-contaminated soil on which Panax notoginseng was grown. The following three treatments were used:i) control soil amended with wheat bran but without YNS-85, ii) soil with 0.15 kg m^-2 of solid bacterial inoculum (A), and iii) soil with 0.30 kg m^-2 of solid bacterial inoculum (B). The removal of soil PCNB during the microbial remediation was monitored using gas chromatography. Soil catalase and fluorescein diacetate (FDA) esterase activities were determined using spectrophotometry. In addition, cultivable bacteria, fungi, and actinomycetes were counted by plating serial dilutions, and the microbial biodiversity of the soil was analyzed using BIOLOG. After 1 year of in-situ remediation, the soil PCNB concentrations decreased significantly by 50.3% and 74.2% in treatments A and B, respectively, when compared with the uninoculated control. The soil catalase activity decreased in the presence of the bacterial isolate, the FDA esterase activity decreased in treatment A, but increased in treatment B. No significant changes in plant biomass, diversity of the soil microbial community, or physicochemical properties of the soil were observed between the control and inoculated groups (P<0.05). The results indicate that Cupriavidus sp. YNS-85 is a potential candidate for the remediation of PCNB-contaminated soils under P. notoginseng.     

Long-term nitrogen balance for pearl millet (Pennisetum glaucum L.) in an acid sandy soil of Niger

On acid sandy soils of Niger (West Africa) fertilizer N recovery by pearl millet (Pennisetum glaucum L.) is often more than 100 per cent in years with normal or above average rainfall. Biological nitrogen fixation (BNF) by N₂-fixing bacteria may contribute to the N supply in pearl millet cropping systems. For a long-term field experiment comprising treatments with and without mineral fertilizer (F) and with and without crop residue application (CR) a N balance sheet was calculated over a period of six years (1983-1988). After six years of successive millet cropping total N uptake (36-77 kg N ha^?1 yr^?1) was distinctly higher than the amount of fertilizer N applied (30 kg N ha^?1 yr^?1). The atmospheric input of NH₄-N and NO₃-N in the rainwater was about 2 kg N ha_?1 yr^?1, 70 % in the form of NH₄-N. Gaseous NH₃ losses from urea (broadcast, incorporated) were estimated from other experiments to amount to 36 % of the fertilizer N applied. Nitrogen losses by leaching (15 to > 25 kg N ha^?1 yr^?1) were dependent on the treatment and on the quantity and distribution of single rainfall events (>50 mm). Decline in total soil N content (0-60 cm) ranged from 15 to 48 kg N ha^?1 yr^?1. The long-term N balance (1983-1988) indicated an annual net gain between 6 (+CR-F) and 13 (+CR+F) kg N ha^?1 yr^?1. For the control (-CR-F) the long-term N balance was negative (10 kg N ha^?1 yr^?1). In the treatment with crop residues only, the N balance was mainly determined by leaching losses, whereas in treatments with mineral fertilizer application the N balance depended primarily on N removal by the millet crop. The annual net gain in the N balance increased from 7 kg ha^?1 with mineral fertilizer to 13 kg ha^?1 in the combination mineral fertilizer plus crop residues. In both the rhizosphere and the bulk soil (0-15 cm), between 9 and 45% of the total bacterial population were N₂-fixing (diazotrophic) bacteria. The increased N gain upon crop residue application was positively correlated with an increase in the number of diazotrophic and total bacteria. The data on bacterial numbers suggest that the gain of N in the longterm N balance is most likely due to an N input by biological nitrogen fixation. In addition, evidence exists from related studies that the proliferation of diazotrophs and total bacteria in the rhizosphere due to crop residue application stimulated root growth of pearl millet, and thus improved the phosphorus (P) acquisition in the P deficient soil.     

Controls on soil respiration in semiarid soils

Soil respiration in semiarid ecosystems responds positively to temperature, but temperature is just one of many factors controlling soil respiration. Soil moisture can have an overriding influence, particularly during the dry/warm portions of the year. The purpose of this project was to evaluate the influence of soil moisture on the relationship between temperature and soil respiration. Soil samples collected from a range of sites arrayed across a climatic gradient were incubated under varying temperature and moisture conditions. Additionally, we evaluated the impact of substrate quality on short-term soil respiration responses by carrying out substrate-induced respiration assessments for each soil at nine different temperatures. Within all soil moisture regimes, respiration rates always increased with increase in temperature. For a given temperature, soil respiration increased by half (on average) across moisture regimes; Q₁₀ values declined with soil moisture from 3.2 (at −0.03 MPa) to 2.1 (−1.5 MPa). In summary, soil respiration was generally directly related to temperature, but responses were ameliorated with decrease in soil moisture.